GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
GLAST Large Area Telescope:
Gamma-ray Large
Area Space
Telescope
Tracker Subsystem
WBS 4.1.4
Robert Johnson
Santa Cruz Institute for Particle Physics
University of California at Santa Cruz
Tracker Subsystem Manager
rjohnson@scipp.ucsc.edu
LAT-PR-01967
4.1.4 Tracker Overview
1
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Review Outline
1. Overview
2. Requirements summary
3. Design
4. Verification
5. Fabrication summary
6. Risks and Schedule
7. Appendix A: Requirements details
8. Appendix B: Fabrication details
LAT-PR-01967
4.1.4 Tracker Overview
8 min
5 min
55 min
30 min
5 min
20 min
2
GLAST LAT Project
LAT-PR-01967
CDR/CD-3 Review, May 12-15, 2003
4.1.4 Tracker Overview
3
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Tracker Design Overview
• Stiff composite panels (>500 Hz)
– Allows small gap between x-y SSD
layers
• Tungsten foils on panel bottom
• SSDs on top & bottom faces
• Electronics on panel edges
– Minimizes the gap between towers
(1.59 cm Si to Si)
• Carbon-fiber walls for vertical support
– Very stiff box structure
– Passive cooling to tower base
• Flexure attachment to Grid
– Decouple from thermal expansion
– Lowest frequency >150 Hz
– Greatly reinforced attachment to
the bottom tray.
– Thermal straps couple sidewalls to
the Grid (not shown)
LAT-PR-01967
Multi-Chip
Electronics
Module (MCM) 19 Carbon-Fiber
Tray Panels
Carbon-Fiber
Sidewalls
(Aluminum
covered)
2 mm gap
CarbonFiber Wall
Readout
Cable
Titanium
Flexure
4.1.4 Tracker Overview Mounts
4
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Tracker Design Overview
Close-up view of the interfaces on the bottom of a Tracker module.
This interface has been substantially redesigned since the May ’02
random vibration tests of the prototype tower module, during which
structural failures occurred in the carbon-carbon closeouts of the
bottom tray.
LAT-PR-01967
4.1.4 Tracker Overview
5
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Tracker WBS & Interfaces
Thermal
Straps
Interface Control Documents
–Mechanical: LAT-SS-00138
–Electrical: LAT-SS-00176
LAT-PR-01967
4.1.4 Tracker Overview
6
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Tracker Organization Chart
GLAST LAT IPO
SLAC
R. Johnson, UCSC
Subsystem Manager
H. Sadrozinski, UCSC
Tracker Scientist
T. Ohsugi, Hiroshima
SSD Design,
Testing, Procurement
T. Borden, SLAC
Mechanical-Thermal
System Engineer
J. Tice, SLAC
I&T Supervision
M. Goossens, Teledyne
Manager, MCM assembly
(Contractor)
R. Bellazzini, INFN-Pisa
Italian TKR Project
Manager
D. Nelson, SLAC
Electronics System
Engineer
A. Brez, INFN-Pisa
Development Engineer,
Production Supervisor
M. Sugizaki, UCSC
Electronics Testing
Nicolla Mazziotta, INFN-Bari
Tracker Production Testing
J. Olson, SLAC
Readout-Controller
ASIC Design
E. Swensen, Hytec
Mechanical Engineering
Design
(Contractor)
LAT-PR-01967
E. Spencer, UCSC
F.E. ASIC Design
4.1.4 Tracker Overview
7
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Peer Review and RFA’s
• Significant Findings
– Design maturity, qualification and verification planning are near CDR
level, but still missing verification by EM testing.
– The Tracker is near ready for manufacturing in some aspects, but other
items need to wait until successful engineering model testing has been
accomplished.
• 39 RFA’s
– We have responded to all 39 (see Tracker web page)
– We have received comments back on 20 responses
– 10 RFA’s were closed
• 2 concerns
– Lateness of EM tower environmental testing.
• Bottom-tray and sidewall fabrication will start only when EM testing is
complete.
– Document status: IDD not released and only 50% of flight
drawings released.
• Some progress to show on this since the peer review.
LAT-PR-01967
4.1.4 Tracker Overview
8
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Key Tracker Requirements
• Tracker Level-3 requirements: LAT-SS-00017
• Tracker Level-4 requirements: LAT-SS-00134 & LAT-SS-00152
• Science Requirements that flow down to the Tracker design:
– Effective Area
– Field of View (aspect ratio)
– Point Spread Function
– Background Rejection
– Dead Time
• Low Power: <155 Watts for ~900,000 channels
• Low Noise: occupancy <104 per trigger
• High Rate: <10% dead time at 10 kHz
• High Detection Efficiency: >98%
• Mass: 510 kg allocated to Tracker (reserves held by IPO)
LAT-PR-01967
4.1.4 Tracker Overview
9
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Tracker Mass Breakdown
1 Module
16 Modules
Mechanical Structures
15.8 kg
252.9 kg Calculated
Silicon-strip detectors
4.3 kg
68.8 kg Calculated
Tungsten foils
9.2 kg
147.0 kg Calculated
Electronics and cabling
2.2 kg
35.8 kg Measured
Thermal straps
0.3 kg
4.2 kg Calculated
Total
31.8 kg
508.7 kg
• See LAT-TD-00177 for a much more detailed breakdown.
• Check on the mass of the tray, from two EM prototypes:
• Std tray without W, no SSDs, no MCMs: 52010 g meas., 550 g calc.
• Std tray with W, no SSDs, no MCMs:
83010 g meas., 821 g calc.
LAT-PR-01967
4.1.4 Tracker Overview
10
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Tracker Drawing Status
• A link to the Tracker drawing tree can be found
on the Tracker web site.
• There are 87 drawings for the Tracker flight
hardware.
• No new drawings are needed.
• 14 drawings are still being worked.
• 73 drawings are released.
LAT-PR-01967
4.1.4 Tracker Overview
11
GLAST LAT Project
LAT-PR-01967
CDR/CD-3 Review, May 12-15, 2003
4.1.4 Tracker Overview
12
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Design Requirements: Grid Motion
• Tracker-to-Grid Maximum Interface Distortion
– Superimposed on MECO design limit loads
– NOT superimposed on vibration analysis or testing
Flexure Location
0° Midside Flexure
+45° Corner Flexure
+90° Midside Flexure
+135° Midside Flexure
-180° Midside Flexure
-135° Midside Flexure
-90° Midside Flexure
-45° Midside Flexure
Displacements
Radial (µm)
Vertical (µm)
46
93
81
165
14
91
-60
24
-29
0
20
0
0
0
-11
13
Source: LAT-SS-00788-01-D4, “LAT Environmental Specification,” 15 Nov 2002.
LAT-PR-01967
4.1.4 Tracker Overview
13
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Design Requirements: Flexure Loads
• Corner Flexure Maximum Design Limit Loads
– Maximum from two CLA cycles
Load Direction
Shear
Tension
Compression
Flexure Design Limit Loads
(N)
1003
1277
1277
Source: LAT-SS-00788-01-D4, “LAT Environmental Specification,” 15 Nov 2002.
• Side Flexure Maximum Design Limit Loads
– Maximum from two CLA cycles
Load Direction
Shear
Tension
Compression
Flexure Design Limit Loads
(N)
2266
391
391
Source: LAT-SS-00788-01-D4, “LAT Environmental Specification,” 15 Nov 2002.
LAT-PR-01967
4.1.4 Tracker Overview
14
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Design Requirements: Sine Vibe
Frequency
(Hz)
Acceptance Test Levels
5 to 6.2
Thrust
6.2 to 50
Lateral
5 to 50
Axis
Test Levels
Sweep Rate
1.27 cm (0.5 in.) double amplitude
1.0 g (zero to peak)
0.7 g (zero to peak)
4 oct/min
N/A
4 oct/min
Proto-Flight Qualification Test Levels
5 to 7.4
1.27 cm (0.5 in.) double amplitude
Thrust
7.4 to 50
1.4 g (zero to peak)
5 to 6.2
1.27 cm (0.5 in.) double amplitude
Lateral
6.2 to 50
1.0 g (zero to peak)
4 oct/min
4 oct/min
Qualification Test Levels
5 to 7.4
1.27 cm (0.5 in.) double amplitude
2 oct/min
Thrust
7.4 to 50
1.4 g (zero to peak)
5 to 6.2
1.27 cm (0.5 in.) double amplitude
2 oct/min
Lateral
6.2 to 50
1.0 g (zero to peak)
Source: LAT-SS-00788-01-D4, “LAT Environmental Specification,” 15 Nov 2002.
LAT-PR-01967
4.1.4 Tracker Overview
15
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Design Requirements: Random Vibe
• GEVS Minimum Workmanship applied along all three axes
independently
Acceleration Spectral Density Function
20
80
500
2000
Overall
1.000
Acc & Qual ASD Test Level
(G2/Hz)
0.01
0.04
0.04
0.01
6.8 Grms
0.100
ASD (G 2/Hz)
Frequency
(Hz)
0.010
0.001
10
100
1000
10000
Frequency (Hz)
Source: GEVS-SE Rev A, “General Environmental Verification Specification
for STS & ELV Payloads, Subsystems, and Components,” June 1996,
Section 2.4.2.5.
LAT-PR-01967
4.1.4 Tracker Overview
16
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Design Requirements: Dynamic Clearance
• Maintain positive clearance between adjacent TKR tower modules
(tower-to-tower collisions) (Source: Tracker-LAT ICD)
– Maintain minimum allocation of 1.5 mm for dynamic response of
towers (design gap between towers is 2.5 mm)
• After fabrication/assembly tolerances, alignment, EMI
shielding, static response, & thermal distortion are considered
– Maximum dynamic response goal <145 µm RMS (acceptance)
• Assumes adjacent towers are out-of-phase
• Maintain positive clearance between adjacent trays (tray-to-tray
collisions)
– Maintain minimum clearance of 2 mm between adjacent trays
• Silicon-to-silicon clearance
– Minimum frequency goal of 500 Hz
• Fixed base boundary conditions at tray attachment locations
• Assumes adjacent trays are out-of-phase
LAT-PR-01967
4.1.4 Tracker Overview
17
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Design Requirements: Quasi-Static Loads
• Static-Equivalent Accelerations
Launch Event
Design
Lift-Off/
1
MECO
0.2
6.8
2
Accept3
Qual 3
Unit
3.7
6.8
4.6
8.5
g
g
Lateral
Axial
Transonic
2.34
4.43
Rot X/Y
20.2
rad/s
Rot Z
Scale Factor
20.2
rad/s2
2
1.25
Source
(1) “Summary of the GLAST Preliminary CLA Results,” Farhad Tahmasebi, 11 Dec
2001.
(2) 433-IRD-0001, “Large Area Telescope (LAT) Instrument – Spacecraft Interface
Requirements Document,” May, 2002.
(3) “LAT Tracker Random Vibration Test Levels,” Farhad Tahmasebi, 27 Feb 2002.
LAT-PR-01967
4.1.4 Tracker Overview
18
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Additional Requirements
• Stay Clear Dimensions (Source: Tracker-LAT ICD)
– Straightness ≤ 300 µm from top to bottom
– Maximum outside dimensions (x & y) ≤ 371.7 mm
– Maximum height ≤ 640 mm above grid surface
• Launch Pressure (Source: LAT Environmental Specification)
– Shall survive the time rate of change of pressure per the Delta II
Payload Planner’s Guide, Section 4.2.1, Figure 4.2.
– Extreme pressure conditions are experienced in the first 70 sec of
fairing venting.
• Venting (Source: Tracker-LAT ICD)
– Sufficient venting of all TKR components is required to allow
trapped gasses to release during launch.
• EMI Shielding (Source: Tracker-LAT ICD)
– Each TKR tower shall be covered on all 6 sides by at least 50 µm
of aluminum electrically connected to the Grid.
LAT-PR-01967
4.1.4 Tracker Overview
19
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Tracker Tray with Payload
• The tray “payload” is bonded to the sandwich structure using epoxy, with the
exception of the SSD bonding, which is done with silicone.
– Silicone decouples the thermal/mechanical effects from the tray
SSD’s
BiasCircuit
Structural
Tray Panel
Converter
Foils
BiasCircuit
TMCM
SSD’s
LAT-PR-01967
4.1.4 Tracker Overview
20
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Tray Sandwich Structure
• Lightweight 4 piece machined closeout frame, bonded to face sheets and
core to form a sandwich structure
Gr/CE Face Sheet
C-C Structural
Closeout Wall
1 lb/ft3 Aluminum
Honeycomb Core
LAT-PR-01967
Thermal Boss
C-C MCM Closeout Wall
4.1.4 Tracker Overview
21
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Tray Vibration Testing
• Thin-Converter Tray Vibration Test
– Performed in Albuquerque, NM
– Fixed boundary conditions at
Sidewall attachment locations
– Modal survey in Thrust direction
– Random vibration test to GEVS
general spec @ qualification level
•
LAT-PR-01967
Conclusions
– Measured 710 Hz fundamental
frequency vs. 711 Hz FEA
– No indication of damage after
qualification level (0dB) RV test
– No indication of Carbon
dusting after test
4.1.4 Tracker Overview
22
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Tray Vibration Testing (Con’t)
• Thick-Converter Tray Vibration Test
– Performed in Milan, Italy
– Fixed boundary conditions at
Sidewall attachment locations
– Modal survey in Thrust direction
– Random vibration test to GEVS
general spec @ qualification level
•
LAT-PR-01967
Conclusions
– Measured 580 Hz fundamental
frequency vs. 518 Hz FEA
– No indication of damage after
qualification level (0dB) RV test
4.1.4 Tracker Overview
23
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Sidewall Mounting
• All trays except bottom tray attachment
– M2.5, CRES A286 fasteners
– No metallic inserts in sidewall
• Bottom tray attachment
– M2.5 & M4, CRES A286 fasteners
– Metallic top-hat design inserts in
sidewall
M4
Bottom Sidewall Section
View of Bottom Tray
Sidewall Inserts
M4
M4
(M2.5 fasteners unless
marked otherwise)
LAT-PR-01967
4.1.4 Tracker Overview
24
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
1-yr Chronology of the Bottom Tray
Break
COI Joint Pull Tests
Shake
Final
Design
COI/Hytec
Materials Testing
Hytec
Analysis &
Design
COI Reinforced Tray
LAT-PR-01967
4.1.4 Tracker Overview
25
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Bottom Tray Closeout Walls
• Bonded M55J/RS-3 internal frame for
strength and stiffness
• Machined C-C outside laminate for
thermal transfer of MCM heat and
machining of detail
M55J/RS-3
Internal Frame
C-C Outside
Laminate
MCM Closeout Wall
Structural Closeout Wall
Typical Closeout Wall
Cross-Section
(not to scale)
Actual closeout wall
blanks laid up at COI
and ready for
machining.
LAT-PR-01967
4.1.4 Tracker Overview
26
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Corner Joint Details
Pins
(Reinforce Butt-Joint)
Sandwich Structure w/
Reinforcement Brackets
(Typ, 4 places)
MCM
Closeout Wall
Bonded Butt-Joint
Structural
Closeout Wall
LAT-PR-01967
Corner Reinforcement Bracket
(Bonded)
4.1.4 Tracker Overview
27
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Corner Reinforcement Bracket
• Machined Titanium Reinforcement Bracket
– Strength & Stiffness
Typical Machined Taper
(Reduce Peel Stress)
Sandwich Structure w/
Reinforcement Brackets
(Typ, 4 places)
Corner Block
(Shear Reinforcement)
Slots for M55J Closeouts
(Bonded Interface)
Inside View of Corner
Reinforcement Bracket
LAT-PR-01967
Corner Flexure Mounting Slot
(Press Fit, 2 Pins, 1 Fastener)
4.1.4 Tracker Overview
28
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Bottom Tray with Payload
•
•
SSDs are attached to top side only
Tray payload is bonded to the sandwich structure using epoxy, with the
exception of silicone used to bond SSD’s
– Silicone decouples the thermal/mechanical effects from the tray below
Bias-Circuit
SSD’s
Structural
Tray
LAT-PR-01967
TMCM
4.1.4 Tracker Overview
29
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Tower Finite Element Modeling
Element/Node Count
Number
Number
Number
Number
Number
Number
of
of
of
of
of
of
Grids =
BAR Elements =
Spring Elements =
Solid Elements =
Plate Elements =
Rigid Elements =
227653
1038
63316
120628
56442
219
Mass Properties of FEM
Mass = 32.48 kg
Center of Gravity Location:
Xcg = -1.06E-5 m
Ycg = -4.26E-7 m
Zcg = 0.2623 m
LAT-PR-01967
4.1.4 Tracker Overview
30
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Tower Modal Analysis
• Primary Modes with Mass Participation Factors
Mass Participation Factors
Mode # Frequency (Hz)
T1
T2
T3
Mode Shape Description
1
182.1
0.2%
76.3%
0.0%
Lateral Y - First Bending Mode
2
183.6
74.9%
0.2%
0.0%
Lateral X - First Bending Mode
3
379.0
0.0%
0.0%
76.7%
Axial Thrust Z
4
461.8
0.0%
0.0%
0.0%
Torsional Z axis
5
462.5 - 496.9
0.0%
0.0%
0.0%
SuperGlast Tray Bending Modes
9
527.2
0.0%
0.0%
0.3%
Top Tray Bending Mode
10
548.0 - 549.5
0.0%
0.0%
0.0%
Standard Tray Bending Modes
20
577.8
21.4%
0.0%
0.0%
Lateral X - Second Bending Mode
21
580.1
0.0%
19.9%
0.0%
Lateral Y - Second Bending Mode
22
661.4
0.0%
0.0%
1.6%
2nd/3rd Tray Bending Mode - In Phase
24
834.8
0.0%
0.0%
8.9%
All Trays w/Bottom in Bending Mode - In Phase
LAT-PR-01967
4.1.4 Tracker Overview
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GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Tower RV Analysis: Accelerations
• Equivalent quasi-static accelerations from random vibration input
Vibration Direction
Input Levels
1 Sigma Grms
CG Response
3 Sigma Grms
CG Response
Accept.
Qual
Qual
Qual
Lateral X
6.8
6.8
8.9
26.7
Lateral Y
6.8
6.8
9.0
27.0
Axial Z
6.8
6.8
12.0
36.0
Lateral 45XY*
6.8
6.8
8.9
26.6
* For Reference Only
19th Tray
Response
20.0
18.0
Qual
16.0
14.0
10th
Tray
Response
Grms
12.0
10.0
8.0
6.0
4.0
2.0
0.0
0
Bottom Tray
Response
LAT-PR-01967
0.15
0.3
Z Height (m)
4.1.4 Tracker Overview
0.45
0.6
32
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Tower RV Analysis: RMS Displacements
Displacement Direction (µm)
X
Y
Z
RV in X (1RMS)
67
1
14
RV in Y (1RMS)
1
67
14
RV in Z (1RMS)
2
0
10
1.18
1.15
9.29
Min M.S.
Tower RV in Y Responses
10.000
Qual Base Input 6.8 Grms
Bottom Tray Response 7.7 Grms
Tower CG Response 9.3 Grms
1.000
Acceleration (G^2/Hz)
• Maximum RMS Response to
Acceptance Level RV Input
• Min MS is +1.15
Tower Tip Response 17.8 Grms
0.100
0.010
0.001
0.000
10.0
100.0
1000.0
Frequency (Hz)
LAT-PR-01967
4.1.4 Tracker Overview
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GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Tray Finite Element Modeling
• Tray FE models were constructed
for all five tray types
• Modal and random vibration
analysis performed
• Results are summarized in HTN102070-0005
Detailed HYTEC Tray FEM
(Top, Thin-, No-Converter)
Detailed INFN Tray FEM
(Thick-Converter)
LAT-PR-01967
4.1.4 Tracker Overview
34
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
FE Modal Analysis Results
Tray Description
Top Tray
Thin-Converter Tray
Thick-Converter Tray
No-Converter Tray
Bottom Tray
Frequencies (Hz)
Without Payload
With Payload
Stiffness Effects
Stiffness Effects
569
584
N/A
718
767
673
711
518
764
788
• Fixed Base Boundary Conditions
– Simply supported at sidewall
attachment locations
• Payload stiffness effects include
Tungsten and bias-circuits
– Silicon applied as mass only
Typical 1st Mode Shape of
the Thin-Converter Tray
LAT-PR-01967
4.1.4 Tracker Overview
35
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Bottom Tray Finite Element Modeling
• Fidelity of FEM is sufficient to calculate stresses
• Analysis is done in the tower configuration
• Static analysis is used to estimate stresses during design phase
– Equivalent static accelerations calculated to simulate 3σ random
vibe environment
• Random-Vibe Analysis is used to calculated RMS stresses to finalize
design
LAT-PR-01967
4.1.4 Tracker Overview
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GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Analysis FS, MUF & MS Requirements
• Factors-of-Safety on Static & Random Vibration Loads/Stresses Applied to
Design Levels
– Metallic Structures1
• Ultimate Design Factors-of-Safety = 1.4
• Yield Design Factors-of-Safety = 1.25
– Composite/Bonded Structures2
• Ultimate Design Factors-of-Safety = 1.5
– Qualification Test Factor1,2 = 1.4
• Model Uncertainty Factor (MUF)
– MUF applied to analysis = 1.15
• Previous prototype testing and model validation/verification
• Margins-of-Safety
– Margin-of-Safety Equation = Sallowable/(FS * Smax) – 1
– All Margins must be above 0.00
Reference: NASA-STD-5001
1) Table I, Section 5.1.1
2) Table III, Section 5.1.3
LAT-PR-01967
4.1.4 Tracker Overview
37
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Bottom Tray Minimum Margins:
Tension
Zero
Compression
LAT-PR-01967
4.1.4 Tracker Overview
38
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Side Wall & Screw Margins of Safety
• Insert MS is calculated using the interaction of the vertical and
lateral loads
Basic Interaction Eqn: MS 
LAT-PR-01967
1
 1 Where:
Rx 2  Ry 2
Ri 
i
 allowable
4.1.4 Tracker Overview
Tension
Zero
Compression
39
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Tray’s 2-19 Minimum Margins
(Bottom Tray Not Shown)
Tension
Zero
Compression
LAT-PR-01967
4.1.4 Tracker Overview
40
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Flexure-to-Grid Attachment Configuration
•
•
•
•
•
8-Flexure Configuration
– 4 in each corner
– 4 along each side
Allows radial distortion of grid due to thermal input
Material: 6Al-4V Titanium, Annealed
Tapered 3-Blade Design
Center stiffener to increase critical buckling
LAT-PR-01967
4.1.4 Tracker Overview
41
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Flexure Margins
Corner Flexures:
Load Case
Interface Design Loads
Liftoff & Transonic
MECO + Grid Distortion
Random Vibration Loads
RV Loads along 45 Axis
Grid Thermal Distortion
Margin-of-Safety
Ultimate
Yield
0.29
0.33
0.90
0.96
1.02
1.09
0.22
0.26
0.27
0.32
0.51
0.56
von Mises
Stresses from
Normal Load
Note: All Margin calculations include fabrication tolerances
Side Flexures:
Load Case
Interface Design Loads
Liftoff & Transonic
MECO + Grid Distortion
Random Vibration Loads
RV Loads along 45 Axis
Grid Thermal Distortion
Margin-of-Safety
Ultimate
Yield
0.25
0.29
0.93
0.99
1.05
1.11
0.41
0.46
0.42
0.47
0.42
0.47
Note: All Margin calculations include fabrication tolerances
LAT-PR-01967
4.1.4 Tracker Overview
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GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Heat Strap Analysis: Stress Analysis
• Maximum load case is the lateral
random vibration
– Shear deformation shown below
• Minimum Margin-of-Safety is +0.52
Von Mises Stresses
High
Medium
Low
LAT-PR-01967
4.1.4 Tracker Overview
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GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Thermal Design Requirements
• Tracker Temperature Requirements
– Maximum heat load = 10.2 W
– Maximum Temperature of SSDs = 30°C
• Tracker Temperature Limits:
State
Qualification
Acceptance Test
Operating
Low Temp Limits
(°C)
-30
-20
-15
High Temp
Limits
+50
+30
+30
Survival
(°C)
Low = -30
High = +50
N/A
Source: LAT-SS-00778-01-D4, “LAT Environmental Specification,” 15 Nov 2002.
LAT-PR-01967
4.1.4 Tracker Overview
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GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Thermal Design Overview
• 16 identical towers (19 trays each)
– 10.2W (hot) and 8.7W (cold)
per tower, located on MCM
boards
– Primary heat path is from MCM
closeouts on each tray to high
conductivity walls (K13D),
down walls to Grid through
copper heat straps
•
•
•
•
2.55 W per strap (hot)
RTV interface at Tracker
Bolted (dry) at Grid
Interface Delta T is <3°C
cables
– High emissivity external
surfaces (black paint) promote
radiation between towers and
from towers to ACD
LAT-PR-01967
4.1.4 Tracker Overview
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GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Electronics Cooling
• Low IC power density (20 MHz clock):
– GTFE chip: 7.8 mW for 0.33 cm2  0.024 W/ cm2
– GTRC chip: 32 mW for 0.12 cm2  0.26 W/cm2
• Total MCM power of 0.25 W is spread by the PWB over about 100
cm2 along the tray edge  2.4 mW/cm2. The 8-layer board has
several full copper planes to spread the heat.
• The MCM is bonded to the carbon-carbon closeout with epoxy.
• The carbon-carbon carries the heat to the sidewall through a 20 cm
long boss and 10 fasteners into the tower sidewalls.
• SSDs stay below 30°C operational. The ICs will be only a few
degrees warmer.
LAT-PR-01967
4.1.4 Tracker Overview
46
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Thermal Model
+Z
• SINDA/TSS Model
– 82 Nodes/Tower, 1312 total
• Trays are lumped into groups
per tower
–
–
–
–
–
–
Top tray
Top 5 Standard Trays
Bottom 6 Standard trays
Heavy Trays
Standard No Converter trays
Bottom Tray
8
13
4
0
9
5
1
14
10
6
2
11
15
7
3
• Each Tray Group consists of 1
Tray node, 4 closeout nodes (Q
input), 8 wall nodes
• Copper strap interface to Grid
nodes
LAT-PR-01967
+Y
12
+X
4.1.4 Tracker Overview
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GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Thermal Simulation Results – Hot
• Steady State
Temperatures
– Max DT up wall is
6°C (7°C including
entire tower)
– Max Temp, +24°C
°C
Steady State Temperatures
+Z
+Y
15
0
• Located at Bay 5,
Top 5 Std Closeout
Trays
• Transient Temperatures
– Max Tracker
Transient, +24°C
W
167.4
-20.1
-147.4
0.0
Energy Balance
Tracker Dissipation
to ACD
to Grid
SUM
LAT-PR-01967
+X
Internal View
4.1.4 Tracker Overview
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GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Thermal Simulation Results – Hot
°C
• Simulate complete
failure of the GridTower interface
(copper straps) in the
center tower (Bay 5).
• DT steady state
increase is 4.4°C
– Max Temp is now
+28.4°C
LAT-PR-01967
Bay 4
Bay 5
4.1.4 Tracker Overview
Bay 6
49
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Thermal Results - Survival
• Minimum Tracker Survival Temperature is –24 °C
Tracker Bay 5 Survival Temperatures over 5 Orbits
0
0
50
100
150
200
250
300
350
400
450
500
Temperature, C
-5
-10
-15
-20
Top Tray
-25
Time over 5 orbits, min
LAT-PR-01967
4.1.4 Tracker Overview
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GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Tracker Electronics Design
• The major challenges:
– Low power: <168 W of conditioned power
• Less than 0.29 W per MCM or 190 W/channel
• The flight design achieves 0.25 W per MCM!
– Low noise occupancy: (noise trigger rate <500 Hz)
• The trigger requires occupancy less than 5/100,000 ch/trigger
• Readout and onboard processing requires <1/10,000 ch/trigger
• The beam-test/balloon flight tracker achieved much better…
– Compact packaging: bring signals around the tray corner
– Manufacturing and QC: 884,736 channels, >98% functional
– Reliability: design, redundancy, testing
• Implementation: 2 ASIC designs and chip-on-board technology.
• Reliability:
– Redundant readout and control paths.
– Redundant power paths.
– Protection against power shorts.
LAT-PR-01967
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GLAST LAT Project
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Tracker Readout Architecture
Emphasis on compactness, minimum of wiring, and redundancy:
•
•
•
•
Serial, LVDS readout and control lines on flat flex-circuit cables.
Either of the two communications cables can fail without affecting the other.
Two readout and control paths for every 64-channel front-end chip.
Any single chip can fail without preventing the readout of any other.
24 64-channel amplifier-discriminator chips for each detector layer
• Trigger output = OR
of all 1536 channels
in a layer.
LAT-PR-01967
GTRC
Control signal flow
GTRC
Control signal flow
GTRC
• Read command
moves data into 1 of
2 GTRC buffers.
• Token moves data
from GTRCs to TEM.
GT FE
GT FE
GTRC
Nine detector layers are read out on each side of each tower.
GTRC
GTRC
9-99
8509A22
Data flow to FPGA
on DAQ TEM board.
2 readout
controller chips
for each layer
4.1.4 Tracker Overview
Data flow to FPGA
on DAQ TEM board.
52
Control signal flow
• Upon trigger (6-fold
coincidence) data are
latched into a 4event-deep buffer in
each front-end chip.
Data flow
GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
A2
A1
A0
NSDATA_IN
A3
TREQ_IN
LEFT
GTFE
RD_IN
NTREQ
GTRC
CTRLREG
TACKB
NSCMD
SCMD_OUT
A2
A1
A0
CLKB
RESETB
NSDATA_IN
A3
NTOKEN_OUT
NRESET
TOKEN
CLK
NSDATA
NTACK
TREQ_IN
LEFT
GTFE
RD_IN
NTREQ
GTRC
CTRLREG
TACKB
NSCMD
SCMD_OUT
CLK
NRESET
NSDATA
NTACK
TOKEN
• Block diagram of the ends of two
readout layers and their connections
to the TEM
– Clock, Command, Trigger, and
Reset are bussed to the GTRC
chips
– Token and Data daisy-chain up
and down the 9 layers
– Each layers sends its Layer-OR
directly to the TEM
– The TEM communicates only
with the GTRC chips, always by
serial LVDS.
– The GTRC communicates with
24 GTFE chips on the MCM.
NTOKEN_OUT
Tracker Readout Architecture
CLKB
RESETO
RESETB
TEM
LAT-PR-01967
4.1.4 Tracker Overview
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GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
MCM Readout Module Configuration
•
•
•
•
•
•
•
8-layer polyimide PWB
Top edge thickened and machined to a 0.80 SSD
mm radius
Kapton Bias
1-layer flex circuit (“pitch adapter”) bonded Circuit
Tray Structure
over the radius
Fully encapsulated wire bonds
Conformal coating
2 Omnetics nano connectors
Adhesive
Steel alignment pins + adhesive
GTRC, 1 of 2
Pitch-adapter
flex bonded
over radius
ASIC
MCM
PWB
GTFE, 1 of 24
359.0mm
24.58mm
18.0mm
Connector, 1 of 2
Grounding Screws
3 Total
LAT-PR-01967
Mounting Screws, 1 of 8
4.1.4 Tracker Overview
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GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Pitch Adapter
• 1-layer Kapton flex circuit
• Ni + Au plating for wire bonding
• Precision tooling holes (not
shown)
• Circuit & traces are trimmed to
length after bonding to the PWB
Bias HV
ASIC Side
SSD Side
(228 m pitch)
“ground”
LAT-PR-01967
4.1.4 Tracker Overview
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GLAST LAT Project
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Prototype Electronics Performance
• See LAT-TD-1090. Reviewed at TKR ASIC review Dec 6, 2002.
• Analog tests with “mini-MCM” plus full-length ladder (384 channels)
– Gain and noise from charge-inject/threshold scans
– Noise measurements from trigger-rate threshold scans
– Noise occupancy from random triggers
– Noise injection from digital readout
– Gain versus number of channels pulsed
– Pulse shapes and Time-Over-Threshold
• Functional tests with full MCMs (no SSDs attached)
– All digital functionality
– Power consumption
– Voltage and timing margins
– DAC calibrations
– Thermal cycling
• Radiation Testing: TID, SEU, and SEL done on prototype ICs.
LAT-PR-01967
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Measured MCM Power Consumption
AVDDA
1.5 V
AVDDB
2.5 V
No Clock
77.4 mW
39.3 mW
20 MHz
77.4 mW
39.3 mW
DVDD
2.5 V
address 5
82.8 mW
134.3 mW
MCM Power (W)
138.5 mW
Allocation
MCM Address > 0
0.251
MCM Address = 0
0.255
Tower
9.05
10.5 W
16 Towers
145
168 W
LAT-PR-01967
DVDD
2.5 V
address 0
4.1.4 Tracker Overview
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Results on the Flight ASICs
• GTFE V-G3: 1 wafer was diced without prior probe testing:
– 21 ICs were mounted on mini-MCMs and 72 on full-size MCMs
– 91 out of 93 randomly selected (unscreened) chips worked 100%.
– No evidence of the comparator instability that plagued the previous version
(all 93 chips show nearly identical behavior, with stable Layer-OR outputs
even at the minimum threshold setting).
– The timing margin on the register read-back was corrected:
• Chips on the full-size MCMs load and read correctly at VDD=2.5V up to
28 MHz (old versions fail at 23 MHz or less).
• Chips also load and read correctly at VDD=2.25V and 20 MHz.
– Two mini-MCMs were connected to full-size ladders. Noise performance
is similar to the previous versions.
• GTRC V-6: 1 wafer was diced without prior probe testing
– Tested with probe card & test suite, as well as on mini-MCM and full MCM
– All functionality is correct.
– Timing margin improved: data readout works up to 30 MHz at 2.5V
• >20 wafers have by now been tested with ~95% yield.
LAT-PR-01967
4.1.4 Tracker Overview
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EMI/EMC
• Requirements document: 433-RQMT-005
• The Tracker will be well shielded:
– All transmitted signals are LVDS and digital (very low radiation and
excellent noise rejection). In addition, power and ground reference
planes are always directly under or over the signal pairs.
– Aluminum foil (over carbon-fiber) covering all 6 tower module sides.
– Conductive tape around the corners to connect the sides.
• SSD strips are the sensitive nodes, but
– They are well shielded from any radiation.
– Only a very local reference is needed (the amplifiers are millimeters from
the strips with well identified, short current return paths).
– The local grounding around the SSDs is critical for noise performance.
• EM emissions will be tested from the qual unit, but we expect it to
satisfy requirements easily (433-RQMT-0005). Preliminary
measurements on the BTEM showed no measurable emission, even
with the aluminum shielding walls removed.
LAT-PR-01967
4.1.4 Tracker Overview
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GLAST LAT Project
LAT-PR-01967
CDR/CD-3 Review, May 12-15, 2003
4.1.4 Tracker Overview
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GLAST LAT Project
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Engineering-Model Towers
• Mini-Tower
– 3 functional X-Y detector planes (3 X layers and 3 Y layers).
– Develop and test tray assembly procedures with real electronics and
detectors.
– Test the readout electronics in a realistic environment.
– Test the detector system with minimum-ionizing particles (cosmic rays).
– Exercise the TEM based readout with multiple layers and multiple cables.
– Platform for development of Tracker subsystem test procedures and
software that will be needed for flight-module production.
Carbon– Platform for I&T development.
Fiber Wall
• Full-size Structural/Thermal Tower
– Full Form and Fit Tower
– Flight design and materials for vibration testing
– Full thermal dissipation for thermal-vacuum testing
– Purpose is to develop the mechanical assembly processes and to validate
the mechanical/thermal design.
LAT-PR-01967
4.1.4 Tracker Overview
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GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Mini-Tower
Al “grid” fixture
LAT-PR-01967
4.1.4 Tracker Overview
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GLAST LAT Project
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Mini-Tower Configuration
• The essence:
– 3 instrumented x,y silicon-strip detector planes
– Each x,y plane is preceded by a thin tungsten foil (3% rad. len.)
• The details:
– 4 light composite panels supporting SSD ladders
– 1 bottom tray with no SSD but with the mechanical interface to the grid
• This is an older prototype tray refitted by COI with preliminary versions of the
titanium reinforcement
– 8 short versions of the readout cables
– 8 MCMs (2 for each pair of readout cables)
• The 2 lowest MCMs have no SSDs connected but are required in order to
complete the data transmission circuit
– Inexpensive aluminum walls
• The status:
– Presently assembled with prototype MCMs that are only partly functional,
due to problems with the pitch adapter and prototype ASICs.
– New MCMs with corrected pitch-adapter design and flight ASICs, plus
new cables, are in production to refit the mini-tower in late May.
LAT-PR-01967
4.1.4 Tracker Overview
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GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Extra Functional Tray
• Another tray, instrumented on both sides with SSD and electronics,
plus thin converter foils, is being assembled in Italy. This is in
addition to the Mini-Tower.
• This tray will undergo complete environmental testing to qualification
levels, including
– Random vibration: GEVS (LAT-TD-01004)
– Thermal vacuum: 30C to +50C (LAT-TD-01037)
• This will complement the environmental testing of the mechanicalthermal tower module, which will not include functional detectors and
electronics.
LAT-PR-01967
4.1.4 Tracker Overview
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GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
Example EM Tray
One of 5 functional trays built, using the
first prototype MCMs and preproduction
ASICs.
Encapsulated
ASICs
Bias Circuit
Handle for
assembly fixtures
MCM
Thermal Boss
Connector Saver
LAT-PR-01967
4.1.4 Tracker Overview
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GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
EM Mini-Tower Under Test
Eduardo
Massimiliano
Ric
Selim
Luca
Mini-tower
The mini tower effort has given the LAT collaboration, and specially the I&T group,
the opportunity to build a team of collaborators across the following subsystems:
ELX, I&T, TKR, and SAS.
LAT-PR-01967
4.1.4 Tracker Overview
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Mini-Tower Test Status
• All trays were tested individually with cosmic-ray events, using self
triggering. Significant dead areas are present due to known
problems in the pitch-adapters and ASICs of the first-generation
MCM prototypes presently installed.
• Register readout and charge-injection events are working with all 8
MCMs and 8 cables simultaneously in use.
– This required more time than expected due to it being a learning
experience, including much debugging of TEM firmware, our
EGSE software scripts, and the cable layouts.
– The front-end readout modules have been shown to function in
accordance with their known condition prior to tower assembly.
• We succeeded one week ago to self-trigger the mini-tower and
observe cosmic-ray tracks.
• Final quantitative mini-tower results will be obtained only after
refitting with new MCMs and flight-version ASICs (in progress).
LAT-PR-01967
4.1.4 Tracker Overview
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Leakage Currents
The leakage current remains within specifications for all tested
trays (no damage during assembly).
TG001 Back leakage current
3500
Tray-lab
The leakage current
measured on full trays
is in most cases lower
than the sum of the
single-ladder currents
(but ladders were
tested at 22º average
temperature,
while
trays were tested at
17.5 º).
3000
Expected (sum of
ladderscurrents)
Leakage current (nA)
2500
2000
1500
1000
500
0
0
20
40
60
80
100
120
Bias Voltage (V)
LAT-PR-01967
4.1.4 Tracker Overview
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Noise Trigger Rates
• The noise trigger rate is monitored for each FE chip as a function of
discriminator threshold.
• Residual triggers at high threshold are due to cosmic rays.
Threshold scan FE 21
100000
10000
OR of 64 Channels
Counting rate (Hz)
1000
100
10
1
0,1
0,01
0
10
20
30
40
50
60
Threshold DAC
LAT-PR-01967
4.1.4 Tracker Overview
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GLAST LAT Project
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Cosmic Ray Triggers
Event 1
Two example minitower cosmic-ray
events obtained
from self-triggering
(the standard 3-in-arow trigger)
Time-Over-Threshold:
Event 2
~ 10 s
LAT-PR-01967
4.1.4 Tracker Overview
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GLAST LAT Project
CDR/CD-3 Review, May 12-15, 2003
EM Tower Plan Synopsis
•
•
•
•
•
•
•
•
May 15:
May 27:
June 13:
June 24:
July 8:
July 22:
August 5:
August 15:
LAT-PR-01967
M55J closeouts completed
K13D sidewall panels completed
Bottom tray fabricated
Static load testing completed on bottom tray
EM tower assembled
Vibration testing completed
Thermal-vacuum testing completed
Deliver EM tower to I&T
4.1.4 Tracker Overview
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Tracker Test Matrix
LAT-PR-01967
T
T
T
M
T
T
TQ
TQ
Vibe z-axis only
Vibe & TV only 1
TQ
T
TQ
TQ
M
T
M
T
T
M
M
M
T
T
T
TQ
T
T
T
TQ
TQ
Test 1 to destruction
Vibe 5; z-axis only
T
TQ
T
T
TQ
TQ
TQ
TQ
Comments
TQ
M
TQ
TQ
Other
Radiation
T
Thermal Cycle
T
Thermal Balance
Burn-In
T
Thermal Vacuum
Functional and Power
Stacked Cosmic Ray Test
EDS Compatibility (Grounding)
T
EMI/EMC
Flight Tracker MCMs
Tray panels
Flight Bottom Trays
Flight Tracker Std. Trays
Flight Tracker Towers
Interface Verification
F
F
F
F
F
TQ
TQ
Thermal
Mass Properties
C
C
C
C
S
4
38
36
19
1 TQ
18 A
1 A
Electrical
Pressure Profile
Mini-MCMs (ASICs)
Qualification MCMs
QM Tracker MCMs
Tray panels
QM Bottom Tray
QM Tracker Std. Trays
QM Tracker Tower
Acoustic
Q
Q
Q
Q
Q
Q
Q
Random Vibe + modal survey
C
C
C
C
C
C
S
8
24
5
1
2 TQ
18 A
1 A
Sinusoidal vibration+modal survey
Component (ITEM)
EM Tracker MCMs
Tray panels
Live trays
EM Mini-Tower
EM Bottom Tray
EM Tracker Std. Trays
EM Tracker Tower
Sine Burst (static equivalent acc.)
E
E
E
E
E
E
E
Static Load
Unit Type
C
C
C
C
C
C
S
Mechanical
Quantity
Assembly Level
Hardware
2 for DPA
Vibe z-axis only
A
612
T
323
TA TA
17 TA
T
306
T
17
TA TA TA
M
T
Assembly Level
Unit Type
S= Subsystem
F= Flight
C= Component
Q= Qual
E= Engineering Model
T
T
T
T
T
T
T
T
TQ
TQ
TQ
T
T
T
Vibe z-axis only
T
T
T
T
QS QS
T
TA QS
Verification Method:
T= Test
A= Analysis
M= Measurement
4.1.4 Tracker Overview
TA
TA
QS= Qual by Similarity
TQ= Test, Qual Level
TA= Test, Acceptance Level
72
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Static Proof Test of Bottom Tray Interface
• Validate bottom tray and flexure design with static proof test in the
lateral and vertical direction, scheduled for June ‘03
– Proof test to ±110% of Max expected load
• Two bottom trays will be tested
– 1 will be used in E/M RV test
– 1 will be tested to failure
• Static test goals
– Measure interface stiffness
– Proof test E/M bottom tray
– Verify capability of bottom tray design
– Verify flexure and heat strap design
LAT-PR-01967
4.1.4 Tracker Overview
{Sidewall not
shown for clarity}
73
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Bottom Tray Test Configuration
C.G. Reaction Point
Tower Simulator
Flight Equivalent
Sidewalls
(K13D2U/RS-3)
Tray #2
Bottom Tray
Heat Straps
Flexures
Grid Simulator
Base Reaction
Frame
LAT-PR-01967
4.1.4 Tracker Overview
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Lateral Test Configuration
Base Reaction into
Granite Table
Load Cell
{Not Shown}
Spring Assembly
Reaction Frame
{Outer Plate Not Shown}
LAT-PR-01967
Reaction
Shaft/Nut
4.1.4 Tracker Overview
Displacement
Probes
75
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Vertical Test Configuration
Base Reaction into
Granite Table
{Not Shown}
Reaction
Shaft/Nut
Spring Assembly
Reaction Frame
Load Cell
LAT-PR-01967
Displacement
Probes
4.1.4 Tracker Overview
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Panel Vibration Testing
Tungsten side on the top
Panels undergo acceptance
vibration tests before mounting
MCMs and ladders.
Centrotecnica setup (Milan):
- 1 LDS shake table
- 2 fixtures
- 9 read out channels
Accelerometers:
• Control: two mono-axial accelerometers
positioned on two of the four L-shaped
blocks TP1&TP2
• Fixture: three mono axial accelerometers
placed on a corner on one of the four Lshaped block TP6
• Tray: one three-axial accelerometers in the
middle of panel TP5
LAT-PR-01967
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Panel Vibration Levels
Sine sweep
Frequency
range
20  2000 Hz
Sweep rate
2 oct/min
Maximum
Amplitude
0.25 g0-pk
Random vibration
LAT-PR-01967
Frequency
(Hz)
ASD Acceptance
Level (g2/Hz)
ASD Qualification
Level (g2/Hz)
20
0.01
0.01
20-50
+3 dB/oct
+3 dB/oct
80-500
0.04
0.04
800-2000
-3 dB/oct
-3 dB/oct
2000
0.01
0.01
Overall
6.8 grms
6.8 grms
Duration
1 min/axis
2 min/axis
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Tower Vibration Levels
Low frequency sine sweep
Random vibration
High frequency sine sweep
Frequency
range
20  2000 Hz
Sweep rate
2 oct/min
Maximum
Amplitude
0.25 g0-pk
LAT-PR-01967
Frequency
(Hz)
ASD Acceptance
Level (g2/Hz)
ASD Qualification
Level (g2/Hz)
20
0.01
0.01
20-50
+3 dB/oct
+3 dB/oct
80-500
0.04
0.04
800-2000
-3 dB/oct
-3 dB/oct
2000
0.01
0.01
Overall
6.8 grms
6.8 grms
Duration
1 min/axis
2 min/axis
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Tower Thermal Setup
• Tower covered with a thermal blanket during T-V cycles.
• The temperature of the plate onto which the tower is mounted
is controlled.
• During equilibrium the temperature is measured on all sides
and at various heights throughout the tower.
The tower has 16 thermistors in the readout cables at varying
heights that can be acquired by using the TKR DAQ system.
Additional thermocouples (TBR):
1.+Y sidewall center of the thermal boss of the tray number 1;
2.+X sidewall center of the of the tray number 1, on the center plane;
3.+Y sidewall center of the thermal boss of the tray number 19;
4.+X sidewall center of the of the tray number 19, on the center plane;
5.-X sidewall center of the thermal boss of the tray number 10;
6.-Y sidewall near the center of the tray number 10, on the center plane
LAT-PR-01967
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Tray Thermal Levels
Acceptance
Qualification/Survival
Temperature Range
-20°C  35°C
-30°C  60°C
# of cycles
4
4
Temperature rate
20°C/hr
20°C/hr
Pressure
1 atm T-C
1 atm T-C
Duration @ T extreme
5 hr
5 hr
Total Duration
62 + 2 hr
72 + 2 hr
On orbit temperature range -15°C  30°C
LAT-PR-01967
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Tower A Thermal Levels
Thermal-Vacuum cycling/Qual level
LAT-PR-01967
Ranges
-30°C  50°C
# of cycles
12
Temp. rate
20°C/hr
Pressure
10-5 Torr
Duration @ extreme
12 hr
Total Duration
384 hr + stabilization @ T room
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Tracker Production Overview
Module Structure (walls, flexures,
thermal-gasket, fasteners)
Engineering: SLAC, Italy (Hytec)
Procurement: SLAC, Italy
SSD Procurement, Testing
Japan, Italy, SLAC
SSD Ladder
Assembly
Italy (G&A, Mipot)
Tracker Module
Assembly and Test
Italy
10,368
2592
18
Tray Assembly and
Test
Italy (G&A, Mipot)
342
Electronics Design,
Fabrication & Test
UCSC, SLAC (Teledyne)
Readout Cables
UCSC, SLAC
LAT-PR-01967
342
648
Composite Panel & Converters
Engineering:
SLAC, Italy (Hytec, COI)
Procurement: Italy (Plyform)
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Tracker Production Overview
• SSD receiving & test (LAT-TD-00527).
– At INFN institutes in Pisa and Perugia/Terni
– 41% complete
• Ladder fabrication (LAT-PS-00635).
– Commercial vendors G&A and MIPOT in Italy
– PRR’s completed last September (G&A) and in April (MIPOT)
– 250 flight ladders assembled (about 10%)
• MCM assembly (LAT-DS-01856).
– Teledyne Electronic Technologies
– Second prototype round is in progress
• Tray panel fabrication (LAT-PS-01584).
– Plyform S.R.L. in Italy
– PRR held in April; some RFA’s needing closure
• Tray assembly (LAT-PS-01801 and LAT-PS-01802).
– G&A in Italy
• Tower assembly (LAT-PS-01854 and LAT-PS-01855).
– INFN Pisa
• Environmental testing (LAT-TD-00155 and LAT-TD-01840).
– Alenia Spazio in Rome
LAT-PR-01967
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CCB Actions Affecting 4.1.4 TKR
Change Request #
Description
Status
LAT-XR-00883-01
Hytec Design Consulting
Approved, $40K
LAT-XR-01319-01
Procurement of Silicon Strip
Detectors
Approved, $387K*
LAT-XR-01457-01
Bottom Tray Redesign
Approved, $629K
LAT-XR-01463-01
Assemble Flight Tray Panel
Detail Breakdown
Approved, $0K
LAT-XR-01622-01
Delay of Silicon Strip Detectors Approved, $0K
LAT-XR-01861-01
Hytek Design Support
Approved, $0K
LAT-XR-01752-02
SLAC/HEPL Labor Escalation
Rate Changes
Approved, -$17K
*Directly offset by corresponding funding increase from Japan.
LAT-PR-01967
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Key Deliverable Milestones
Activity
Description
FY 04
FY 05
JAN FE B MAR AP R MAY JUN JUL AUG SE P OCT NOV DE C JAN FE B MAR AP R MAY JUN JUL AUG SE
OCT
P
4.1.4 Tracker
T racker Modules A & B RFI ( for Calibration)
T racker Modules 1 & 2 RFI ( for Calibration)
Flight Tracker T ower 3, 4 RFI
Flight Tracker T ower 5, 6 RFI
Flight Tracker T ower 7, 8 RFI
Flight Tracker T ower 9, 10 RFI
Flight Tracker T ower 11, 12 RFI
Flight Tracker T ower 13, 14 RFI
Flight Tracker T ower 15, 16 RFI
Run Date
04/21/03 15:05
Data Date
04/01/03
© Primavera Systems, Inc.
LAT-PR-01967
G LA ST L A T PR OJ EC T
A V: F loa t to
Le ve l 3 M ile sto nes
Forecast
Baseline
Product Available Date
Forecast
Baseline
Integration Need Date
LT-T7: Level 3 to AV :(tb)
FL-D7 Integration Mil estones CDR
AV : Up Triangle, L3: Down Triangl e
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Sheet 1
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4.1.4 Work Flow Summary
LAT-PR-01967
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4.1.4 Work Flow Summary
LAT-PR-01967
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4.1.4 Work Flow Summary
LAT-PR-01967
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Critical Path
• Silicon Strip Detectors (SSD)
– SSD Procurements
• 8154 SSDs shipped from HPK by 5/31/03
• Balance of SSDs (3381) by 9/30/03
• TMCMs
– From the present best-known schedule for delivery of flight EEE
parts, SLAC will deliver the first set of TMCMs to Pisa 9/17/03.
• Flight Tray Panel Fabrication
– Tentatively begins in mid May, but some RFAs from the PRR and
Peer Review are still being closed (note that the TMCMs are
driving the schedule at present).
LAT-PR-01967
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Budget, Cost Performance
$M, Then-Year Dollars
12
8
4
Actual Commitments
ACWP
BCWP
BCWS+ Planned Commitments
BCWS
0
. .
. .
FY00
LAT-PR-01967
. .
. .
FY01
. .
. .
. .
. .
FY02
. .
. .
. .
. .
. .
FY03
. .
. .
. .
. .
FY04
4.1.4 Tracker Overview
. .
. .
. .
. .
FY05
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Cost/Schedule Status
• Status as of March 31, 2003:
Item
In k$
Budget at Complete
10,915
Budgeted Cost for Work Scheduled (a)
7,400 (a)
Budgeted Cost for Work Performed (b)
6,716 (b)
Actual Cost for Work Performed
6,630
Cost Variance
87
1.3% of (b)
Schedule Variance
-684
-9.2% of (a)
The schedule variance mostly represents the cost of all the
MCM production parts and materials, for which
procurement was not completed in March as originally
planned.
LAT-PR-01967
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Risks TKR-1
•
•
•
•
•
Risk Description:
– Low Tracker MCM yield. Each MCM holds 26 ICs. The MCMs are tested before encapsulation, to allow
for rework. However, rework is costly, and too much rework could make it impossible to hold the
schedule and budget. We need it to be the exception, rather than the rule, but so far, in the EM run,
rework involving IC replacement was needed on the majority of MCMs.
Risk Mitigation:
– Screening and handling procedures need to be improved according to the plan described here.
Risk Impact Assessment:
– Possible delay in tower assembly and increased labor cost at Teledyne.
Risk Mitigation Implementation Plan:
– 1. (Johnson, Sugizaki) Improve IC screening. The GTRC chips were not screened for the EM, some
features of the GTFE were not screened, and the screening was at only 2 MHz due to technical
problems. These systems will be improved and tested. An inker is being added to the probe station to
remove human error in die sorting. We also may need to reject dice close to the wafer edge. (end
March) 2. (Johnson, Ziegler) Improve IC handling. Detailed procedures are being written. (end March)
3. (Borden) Improve testing of the MCM PWB prior to assembly and again prior to die attach. (Mid
April) 4. (Johnson, Sugizaki) Improve the MCM test software to speed up localization, of a bed IC.
(June 1) 5. Improve IC design (done), especially to remove the G-chip oscillation problem.
Current Status:
– May 2, 2003: both probe cards were rebuilt and successfully tested, and the test software now tests
100% of functionality. The wafer testing procedures were completed, reviewed and released. The
cleanroom has been upgraded and inspected. Flight wafers are under test, including automated
inking of bad dice. The yield is excellent, and the known ASIC bugs, including the oscillation
problem, have been demonstrated to be cured in the flight design. The lapping and dicing procedures
were prepared by Clinton & Virmani, and we are preparing to dice 3 wafers under these specs and
retest the assembly procedure at Teledyne on 10 MCMs (to be used to refit the mini-tower).
LAT-PR-01967
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Risks TKR-2
•
•
•
•
•
Risk Description:
– MCM-SSD CTE mismatch. The Tracker MCMs and the SSDs are connected by wire bonds, which are to
be encapsulated. This interface is not yet tested. Since it goes the full width of a tray, there is a risk of
damage from movement during thermal cycling.
Risk Mitigation:
– The flight MCMs are to be fabricated in Polyimide instead of FR4, to lower the CTE (Aramid was
considered but has other undesirable features). The encapsulation will be Nusil silicone, as in the
ladders, which allows some movement with low stress. The interface needs to be tested on the EM.
Risk Impact Assessment:
– Critical Path Impact
Risk Mitigation Implementation Plan:
– Build a complete functional engineering-model tray by mid April(two MCMs) in addition to the ones in
the mini-tower, and put it through full qualification-level thermal-vacuum testing. (May)
Current Status:
– May 2, 2003: The tray panel is in hand, as are the two MCMs and the ladders. The procedure for
encapsulating these bonds is being tested first on some mechanical/thermal EM trays. At present the
design is done and the dams for the adhesive are being made.
LAT-PR-01967
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Risks TKR-3
•
•
•
•
•
Risk Description:
– Tray-panel fabrication start-up. Fabrication of tray panels at Plyform needs to start in early March (i.e.
pre-CDR) unless the rate can be made to exceed current predictions. We have not yet seen a plan
from Italy/Plyform on how to accomplish this, nor have we seen any documentation.
Risk Mitigation:
– SLAC assistance to Pisa in getting documentation and materials in place.
Risk Impact Assessment:
– Critical path impact
Risk Mitigation Implementation Plan:
– Acquire Carbon-Carbon material early from SLAC (done). Procure cores from SLAC (in progress). Tom
Borden travel to Plyform in early February to assist with planning and documentation.
Current Status:
– May 2, 2003: 1. The cores were ordered and already received and shipped to Italy. 2. Tom Borden
traveled to Italy and helped prepared a draft procedure document. 3. We received a detailed schedule
from Pisa for the flight build. It shows that the tray panel fab can start in May instead of March and the
electronics will still be the critical path. 4. The PRR for the panels was held at Plyform in March. Some
issues need to be closed before start of flight production, particularly verification of the new plan to
provide grounding of the core.
LAT-PR-01967
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Risks TKR-4
•
•
•
•
•
Risk Description:
– Procurement of MCM components. MCM production at Teledyne needs to start soon to have MCMs
ready to accept ASICs in late May. The design includes parts that are not yet approved but have 8week lead times (the connectors), parts for which we have been working for a long time for approval
without complete closure (polyfuses), and parts for which we do not have agreement on fabrication
specifications (the PWB and flex). Furthermore, our success rate at SLAC for procuring these items
for the EM was poor. We need Teledyne on contract to help us handle these procurements. The LAT
parts specialist to date has never made any contacts with Teledyne.
Risk Mitigation:
– Increase manpower at SLAC on these procurements. Contract with Teledyne to do all of the parts
receiving.
Risk Impact Assessment:
– Critical path impact.
Risk Mitigation Implementation Plan:
– Have a meeting at Teledyne, including Nick Virmani, as soon as possible to iron out the contract and
specifications to be used for MCM PWB and flex procurements and specifications to be used for MCM
assembly. Action also needs to be taken on the Omnetics nano-connectors to get them approved for
flight.
Current Status:
– May 2, 2003: 1. The meeting at Teledyne was held successfully, clarifying a lot of issues. 2. The
Omnetics connectors were approved and are on order. 3. The HV caps and polyswitches were
approved and are on order. 4. Final PWB and flex prototypes are in hand and being tested. 5. We are
close to getting orders out for the remaining standard resistors and capacitors. The limiting schedule
item is the HV cap, with delivery expected August 1. To gain back schedule, we will carry out the
preproduction run of 36 boards (non-flight boards to deliver to the software group) using non-flight
capacitors of the same type from the same vendor.
LAT-PR-01967
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Appendix A
LAT-PR-01967
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Documentation Status
TKR Level-3
Specification
LAT-SS-00017
TKR Interface Control
Documents
Mech: LAT-SS-00138
Elec: LAT-SS-00176
TKR Level-4
Specification
Mech: LAT-SS-00134
Elec: LAT-SS-00152
Electronics Design
Conceptual: LAT-SS-00168
GTFE ASIC: LAT-SS-00169
GTRC ASIC: LAT-SS-00170
MCM: LAT-SS-00171
GND & Shield: LAT-SS-00173
FMEA: LAT-TD-00178
LAT-PR-01967
Draft documents in italics
Parts & Materials
Mechanical: LAT-SS-00172
Electrical: LAT-SS-00179
Spares Plan: LAT-TD-01379
Procurement Specs
SSD: LAT-DS-00011
Polyswitch: LAT-SS-01116
HV Cap: LAT-PS-1194
GTFE ASIC: LAT-PS-01201
GTRC ASIC: LAT-PS-01222
Flex cable: LAT-PS-01132
PWB: LAT-PS-01448
Fabrication Procedures
Ladders: LAT-PS-00635
Tray panel: LAT-PS-01584
MCM: LAT-PS-01856
Trays: LAT-PS-01801/2
Towers: LAT-PS-01854
Test Plans & Procedures
SSD: LAT-TD-00085/00527
Elec. Plan: LAT-TD-00153
ASIC probe: LAT-TD-01250
GTFE ASIC: LAT-TD-00247
GTRC ASIC: LAT-TD-00248
MCM: LAT-TD-00249
Radiation: LAT-PS-01325
Tray vibration: LAT-TD-00154
Tray thermal: LAT-TD-01839
Tower vibration: LAT-TD-00155
Tower thermal: LAT-TD-01840
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Requirements Flowdown
• The flowdown shown in Foldout D of our NASA proposal is still valid.
• Science Requirements that flow down to the Tracker design:
– Effective Area
– Field of View (aspect ratio)
– Point Spread Function
– Background Rejection
– Dead Time
• These Science Requirements flow down to the Tracker Level-3
Requirements, documented in LAT-SS-00017.
• Other requirements are imposed by the IRD, the Tracker ICDs, and
the LAT environmental specification, LAT-TD-00778.
• The Tracker Level-4 Requirements documents specify our detailed
requirements as they pertain to our specific design implementation.
– Mechanical: LAT-SS-00134
– Electrical: LAT-SS-00152
LAT-PR-01967
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Key Tracker Requirements
Parameter
Requirement
Actual
Verification
Power
<155 W
148 W

T,A
Mass
<510 kg
509 kg

T
Geometric active area
>19,000 cm2
19,630 cm2

A
Conversion efficiency
>65%
65%

A
Converter-sensor spacing
<3 mm
2.9 mm

A
Non-converter material (front)
<35%
33%

A
<5% X0
5.1% X0

A
2-plane spatial resolution
<0.2°
0.17°

A
Dead area
<12%
11.2%

A
Hit efficiency
>98%
(>99% BTEM)

T
Aspect Ratio (FOV)
<0.45
0.42

A
<500 Hz
(<10 Hz BTEM)

T
Effective area:
Point Spread Function:
Inter-tower material
Trigger Noise Rate (Self Trigger)
LAT-PR-01967
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Key Tracker Requirements
Parameter
Requirement
Actual
<0.25 ms
<0.15 ms

T
Dead Time at 10 kHz trigger
<10%
<<10% by A

A,T
Noise Occupancy
<104
(<105 BTEM)

T
Ionization Meas. (1 MIP vs 2 MIP)
>2 
>4  by A

A,T
Trigger Recovery Time
Verification
Radiation Hardness: see electronics design section.
Reliability: see electronics design section and FMEA in LAT-TD-00178.
Structural and Environmental (LAT-TD-00778): see mechanical design section.
Contamination Control: LAT-MD-00404.
Parts Control: LAT-MD-00099.
EMI/EMC: 433-RQMT-0005: see electronics design section.
LAT-PR-01967
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Appendix B
LAT-PR-01967
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Parts & Materials
• Two levels of controlling documentation:
– LAT Level
• LAT-DS-00405 LAT Mechanical Materials and Parts
list
• LAT-SS-00401 LAT EEE Parts Identification List
• LAT-SS-00099 LAT EEE Parts Program Control
Plan
– Tracker Level
• LAT-SS-00172 Tracker Mechanical Parts and
Materials list
• LAT-SS-00179 Tracker Electronics Parts list
• LAT-TD-01379 LAT Tracker Parts and Components
Spares Plan
LAT-PR-01967
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Procurements
•
•
•
•
•
•
•
•
•
•
•
•
•
•
In Progress
SSDs: LAT-DS-00011 (~40%)
Carbon-carbon bars (~50%)
Aluminum cores (100%)
Aluminum inserts
Face-sheet material
Tungsten foils
ASICs (wafers 100%; testing &
dicing in progress)
– GTRC: LAT-PS-01222
– GTFE: LAT-PS-01201
HV caps: LAT-PS-01194
Polyswitches: LAT-SS-01116
QML SMT parts
Nano connectors
PWBs: LAT-DS-01448
Pitch-adapter flex
EGSE & MGSE
LAT-PR-01967
•
•
•
•
•
•
•
•
Starting Soon
M55J material
Sidewall material
Tower fasteners
Titanium flexures and brackets
Thermal straps
Bias circuits
Flex-circuit cables: LAT-PS-01132
Micro-D connectors
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TKR Silicon Strip Detectors
•
•
GLAST has driven the 6” wafer technology:
- Procurement spec: LAT-DS-00011
- Area: 8.95 cm x 8.95 cm
- Thickness: 400
um, pitch 228 um
GLAST
- Very aggressive
specs
Cut-off
(leakage currents, bad strips, dicing)
5261 SSDs received (by Peer Review date);
“Skinny”
4304 tested; 165 reviewed;
38 rejected.
“Skinny” GLAST
Cut-of
– SSD Testing Program:
 QA provisions: LAT-CR-00082.
 Testing at the manufacturer, Hamamatsu Photonics (HPK):
• Detector IV and CV
GLAST
• Test for bad channels (opens, shorts, broken capacitors)
Flight
SSD
 Testing at INFN Pisa or INFN Perugia (LAT-TD-00527)
• Measure alignment of the cut edges with the lithography
• Repeat IV and CV curves (all SSDs)
 Lot testing (using test structures): Hiroshima University
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Ladder Fabrication Flow
• LAT ladder fabrication follows this block diagram (see LAT-PS-00635
and LAT-PS-00831 for details)
WS1: Receiving and
Inspection
Storage
WS2: SSD Edge
Bonding
WS5: Electrical
Tests
Storage
WS6: Wire-Bond
Encapsulation
WS3: Metrology
Storage
WS7: Encapsulation
Inspection
Storage
WS4: Wire Bonding
WS8: Electrical Tests
Storage
WS9: Storage of
Completed Ladders
• Assembly at G&A Engineering (251 flight ladders produced)
• Assembly at Mipot staring up (PRR completed in April)
LAT-PR-01967
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SSD Edge Bonding
Ladder assembly tool
alignment errors
100
90
m
80
• Fast AND precise manual method
• 24 ladder assembly tools used in
parallel
• Very good ladder alignment obtained
70
60
50
40
30
20
10
0
-20
-15
-10
-5
0
5
10
15
m
LAT-PR-01967
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Encapsulation
Dam & Fill encapsulation
Dam: Nusil CV-1142
Fill: Nusil CV-15-2500
Requirements:
1. Height <0.5mm
2. Lateral overflow <0.05mm
3. Coverage of all the bondings and pads
Fast system to verify the
encapsulation height
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Electrical Tests: Results
2000
1800
Leakge current history
Expected
Post-encaps.
1600
current (nA)
1400
1200
1000
800
600
400
200
Depletion voltage
0
1142
ladder ID
1163
1183
1203
1224
1244
1266
70
ladder dep. V
expected from SSD
60
50
The causes of problems 3 and 4
have been corrected,
foreseen rejection rate ∼1%
LAT-PR-01967
40
30
20
10
90
80
70
60
50
40
30
0
20
Electrical test results:
1.
Ladder tested
251
2.
Accepted
243 (97%)
3.
Broken edge
4
4.
Probe accident
1
5.
Not understood
3
150
1121
140
1101
130
1076
120
1054
110
1034
100
1014
Depletion voltage (V)
• Bad channels caused by bonding (coupling shorts)=0.016%
(accepted limit 1%)
• No broken or bad wire-bond connections
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Ladder Fabrication Conclusions
• Ladder fabrication has been successfully started (9% of the ladders
have been produced with a 97% yield; likely increase of the yield to
99%).
• Electrical and dimensional ladder characteristics are well within
specifications
• The production rate is > 10 ladders/day in both assembly centers,
which will work in parallel (G&A Engineering and Mipot), so there are
no schedule issues with this process.
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MCM Assembly Overview
• Parts and materials all approved and presently on order
• Assembly at Teledyne Electronics Technologies (L.A.)
– Right-angle-interconnect assembly
• This is the only non-standard process.
• The long, narrow shape of the board, with raised edge and
large number of ICs, is also unusual and requires special care.
– Connector mounting and soldering of SMT parts
– Die attach
– Wire bonding
– Electronics testing
– Wire-bond encapsulation
– Conformal coating
• SLAC
– MCM acceptance testing and burn-in
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Pitch Adapter Installation
•
•
•
•
Custom tooling developed by Teledyne Electronic Technologies.
Epoxy is screened onto the flex circuit.
Tooling aligns the flex with the PWB and bends it around the radius.
Another tool cuts both edges flush with the PWB.
1
3
2
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Detail of an EM MCM, at One End
Polyswitch
Nanonics Connector
(will be Omnetics)
Pitch-adapter flex circuit
GTRC
ASIC
90° radius
Grounding
screw hole
GTFE
ASIC
Shown prior to wire-bond encapsulation and conformal coating.
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IC Wafer Procurement (Complete)
• Vendor: The MOSIS Service of the USC ISI.
– Checking of design files, including DRC on the layout
– Subcontracting for fabrication of the masks (Dupont)
– Subcontracting the wafer fabrication
• HP/Agilent 0.5 m, 3-metal, epitaxial process (AMOS14TB)
– Thorough electrical testing of process monitors on each wafer
• MOSIS guarantees that the wafers meet the Agilent process
specifications
• MOSIS provides the test results in the form of e.g. physical
transistor parameter, sheet resistance, etc.
– Extraction of Spice model parameters for each wafer lot
• BSIM3 V3.1 models for design verification, especially in case
problems arise
– Shipment of wafers to SLAC
• LAT specifications: LAT-PS-1201 and LAT-PS-1222 (released)
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ASIC Screening
• Procedures, QA provisions, and travelers: LAT-PS-1250
• Detailed descriptions of the test vectors:
– LAT-TD-247 for the GTFE
– LAT-TD-248 for the GTRC
• Carried out in a cleanroom at UCSC
– Conforms with the LAT contamination control plan (LAT-MD-404)
– Conforms with ESD controls of NASA-STD-8739.7
– 100% testing of all functionality
– GTFE performance testing
• Results:
– GTRC (9 wafers) 95% yield
– GTFE (3 Wafers) 93% yield
• Wafer lapping, dicing, inspection
– LAT-PS-01321
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MCM Functional Test
• Complete functional before die encapsulation (LAT-TD-00249)
– Test all register and memory locations
– Test all I/O functions, including LVDS bias levels
– Test all inter-chip communication
– Check power consumption
– Test all amplifiers by charge injection and test the trigger output
– Test for excessive noise or instabilities
• A non-functional IC can be replaced at this point, if necessary, but
our goal is to avoid having to do that.
Interface Card (with cover removed)
VME with COM Card and ADC
Frequency Counter
PC
MCM
DUT
LAT-PR-01967
Adjustable Clock
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Test and Burn-In
• This work will be done in the SLAC clean room in
Building 33.
• The MCMs remain in their closed storage boxes
throughout this procedure.
• A functionality test is done to check that no damage
occurred during encapsulation.
• 9 MCMs are connected to a pair of special flex-circuit
cables (1 is shown at right, with a repeater board).
• 4 such cables pairs are installed in a climatic chamber.
• 8 long cables attach to the repeater boards and exit the
chamber, to connect with a TEM.
• The 36 MCMs are thermal cycled through the required
acceptance cycles.
• The temperature is raised to 85°C for 186 hours for
burn-in. During this time the electronics are continually
exercised and tested.
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EM MCM-Assembly Experience
• Several problems were encountered in the first iteration that limit the
usefulness of the MCMs presently installed on the mini-tower. See
LAT-TD-01495 for a listing of the issues and the lessons learned.
• A second iteration of MCMs is presently in progress, to refit the minitower by the end of May:
– Flight-version ASICs, 100% functional and wafer tested with
greatly improved hardware/software.
– Improved dicing, inspection, and handling of the wafers.
– New pitch-adapter flex-circuit design, with alignment and
breakage issues worked out of it (this was the biggest source of
loss of functionality in the previous MCM design).
– New iteration of the PWB, with small bugs worked out of the
design and with a greatly improved backside insulating layer.
• We are confident that we will reach the specified >98% workingchannels with the new mini-tower MCMs.
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MCM Assembly onto Trays
MCM incoming test:
•
Read out tests
•
Noise level
•
Noisy channels
•
HV test
MCM final test:
•
Read out tests
•
Noise level
•
Noisy channels
•
HV test
Procedure doc: LAT-PS-01802
MCM assembly with adhesive
• Scotchweld 2216 A/B gray
• Adhesive thickness .1mm
• Pattern of adhesive lines to avoid air
trapping
• Pins to align to the closeout
• Area occupancy ∼50% ⇨ Δt≲0.10C
• Wire bond to the bias circuit
The tray is put into the
storage/shipping box and delivered
to G&A for assembly of ladders onto
the tray.
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The Tray Storage Box
• This robust aluminum box provides safe and clean storage & shipping.
• The tray can be fully tested while inside the closed box, connecting the
MCMs to a readout cable via the connector savers.
Fixation screws
Connector saver
protections
Connector savers
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Assembly of Ladders onto Trays
• All the assembly operations under C.M.M.
• Glue spots deposited with automated dispenser
• Microbonding with automated wedge bonder
C.M.M. with touch head and optical head
Ladders vacuum kept on the bridges
Reference dowels
Jig of ladders alignment
Alignment micrometers
Jig of tray alignment
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Ladder positioning
CDR/CD-3 Review, May 12-15, 2003
Assembly phases
Tray positioning
• 1 set of assembly tooling ready
• 5 more sets in fabrication
• Max assembly rate: 15 trays/week
• Planned assembly rate: 10
trays/week
Microbonding
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First results
Requirements:
• Alignment error < 40m
• Planarity 100m
TG02 dw
Planarity
glue pads 5mm
cure time 6h
0.4
ladder alignemnt
4.5
=14m
4
0.3
3.5
Z (mm)
3
0.2
x=47
0.1
0
-0.1
0
100
200
300
400
2.5
x=231
2
x=404
1.5
1
0.5
30
20
25
10
15
5
0
-5
-1
0
-1
5
-2
0
-3
0
Y (mm)
-2
5
0
-0.2
m
• Alignment and planarity of the ladders are within specification
with improvements still possible.
• Tools in production will allow an assembly rate that matches well
the test rate of the trays and towers.
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Tray Cosmic-Ray Test
•
•
•
•
•
Tray acceptance test, burn-in (room temperature), and calibration
4 set-ups in Italy, each with TEM-based EGSE system
Trays remain inside their protective boxes, connected by connector savers
Full set of flight-like flex-circuit cables plus 8 extender cables for each setup
Accumulate cosmic-ray data for about 1 week
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Tray/Tower Test: EGSE in Pisa
Processor & COM Cards
28 V Power
Mini-MCM (DUT)
TEM
Power Module
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Tower Module Assembly Flow
See LAT-PS-01854 and LAT-PS-01855 and for details
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Reference pins
Fixation holes
Safety pins
LAT-PS-01854
Below: pre-engineering
tower ready for
transportation and tests.
Cable opening
Lift system
• Tray assembly system successfully
tested during the pre-engineering
tower test (spring 2002)
• Iteration of the fixture design is in
progress for the EM tower
LAT-PR-01967
Fixture
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Tower Module Assembly
• With the help of a reference system made with precise aluminum
walls, the stack of the trays is fast, accurate, and safe.
• Complete functional test of the tower electronic readout system
before attaching each sidewall.
• The sidewalls are then added. Each tray is referred to precision
holes in the sidewalls, which provides good alignment without
accumulate of errors.
• The system has been tested. The errors were below the maximum
allowable tolerance (0.3mm). The process is fast (<1 day to mount a
tower).
• The tower is a good cosmic-ray telescope. The cosmic rays flux
allows a complete and deep understanding at the single-channel
level in a short time (1 week).
• The fixture design is presently under revision to improve safety
features that are important to avoid SSD damage.
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Tower Storage & Shipping
• Documentation
– LAT-SS-00778, LAT Environmental Specification
– LAT-SS-00134, Tracker Level IV Specification
– LAT-MD-00228, LAT Contamination Control Plan
• Full performance testing before and after shipping (LAT-TD-00191)
• Full as-built documentation delivered with Towers
• Shipping Containers:
– Double containment
• Inner container attaches to vibration fixture
– Aluminum rods at each corner of vibration fixture
– Data logger attached to vibration fixture
» Mechanical shock, temperature, humidity and pressure
– Electronic readout cables secured under tower
– Outer Container: high-density foam and high impact plastic
• Storage in the inner container, in the clean room
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