Photonic Packaging for ASPICs
Linkra srl
MicroTechnologies Dept.
© Linkra s.r.l
Package Design overview
1.
Mechanical design:
•
•
Chip angled 24° respect lensed fiber
CuW material for chip submount adopted to increase thermal drain from chip
with high power dissipated
2. Optical design:
•
Fiber selected
OFS LGBF D0,9 9/125 yellow tigh buffered
with conical lens built in on the tip
AR coating 1520 to 1580 < 0,1% LC UPC connector
3. RF design:
•
4 GPPO connector and HF transition alumina inside
HF microstripe from GPPO to chip RF in pad
and 50 ohm chip resistor to close RF out pad (Nikef chip)
4. Thermal design:
•
•
TEC selected to manage power load up to 8W @ 25 C
10k thermistor soldered close to chip for temperature monitoring
ASPIC Package: Mechanical design
•
Package features:
–
–
–
–
Dual in line DC leads 24+24 pin for I/O DC signals fully available
2+2 extra leads (added to the 48 I/O) for thermal system
management
Optical feedtrougth up to two lensed fiber
4 GPPO for HF port up to 40 GHz
ASPIC Package: HF alumina design
• Many design tested to have a cross check between different solutions
ASPIC Package: HF alumina layout
OUTPUTS
INPUTS 1
2468
3
5
2468
7
1
3
5
7
ASPIC Package: HF alumina Design
RF design and simulation results
•
Simulations of the HF transition alumina to evaluate the selected
configuration of 4 GPPO connectors with HF transition alumina, with
microstripe from GPPO to chip RF input pads
ASPIC Package: HF alumina EM Simulation
• Electrical field propagation simulated with HFSS ANSOFT
ASPIC Package: Thermal Design
Thermal design and simulation results:
• Steady State Thermal Analysis of optical packages:
– Optimization of the die attach process: AuSn vs epoxy resin bonding
process
– (Epoxy resin: Epotek H20 - K (W/m/K)=2.5 vs Eutectic AuSn:
K (W/m/K)=250)
• Thermal management: TEC modelling and simulation (Tenv=
25°C,Tctrl= 15°C). Maximum InP chip power dissipation: 4 W
• Results:
Epoxy Epotek-H20
Tctrl TH1 Tc1
[°C] [°C] [°C]
PTEC V1
[W]
[V]
I1
[I]
T1_sim
[°C]
15
36.41 -6.12 17.56 7.16 1.9349.3
20
33.1 -2.1
25
30.91 3.35 9.09
12.46 5.66 1.5153.34
Eutectic AuSn
Tctrl TH1 Tc1 PTEC V1
[°C] [°C] [°C] [W]
[V]
I1
[I]
T1_sim
[°C]
4.75 1.2458.8
15
29.6 11.29 7.08
3.47 0.9329.7
20
29.05 16.29 6.23
2.94 0.8 34.7
25
28.62 21.29 5.57
2.47 0.6940.2
• CuW material selected for chip submount to increase thermal drain from
chip with high power dissipated
• TEC selected to manage power load up to 8W @ 25 C
• 10k thermistor close to chip for temperature monitoring
ASPIC Package: Design overview
Rendering sample:
ASPIC Package: Optical Design -1
Optical design:
•
•
Chip angled 22° respect to the lensed fiber
Minimum pitch requested between optical port ON CHIP: 500um
ASPIC Package: Optical Design -2
Optical design:
•
New fiber holder designed to allow the optical alignement
process of fiber with less than 500 um pitch (in case of angled
chip)
Previous design 500um fiber pitch
New design 464um fiber pitch
ASPIC Packaging: Process Flow Diagram
chips incoming
inspection
package
assembly
• optical inspection
• leads and RF
submount attach
die attach chip on
CuW submount
substrate attach
on submount
preliminary test
TEC and
submounts
assembly in
package
wire bonding
Lid attachement
final test
fiber alignment
• OE test on alignment
system
ASPIC Packaging: Process overview
1. Assembly
• Die attach on CuW submount with AuSn solder
• CuW submount on TEC and TEC on pkg with attached with thermal
conductive resin
• Electrical connections :
– Wedge bonding with 25um diameter of gold wire for DC connections
– Wedge bonding with 18um diameter of gold wire for HF connections
2. Optical alignment
• Done inside package with microgripper to move lensed fiber
• Active with feedback from PD monitor built in on chip or using SOA
spontaneous emmission measured from external pwrmtr connected
to the fiber
• Fiber fixing with UV resin and thermal post annealing
Optical alignment process overview
•
Optical aligment bench
ASPIC Packaging: Optical alignment process
•
•
•
Loading of package on jig
Inserting of fiber in hold position
Loading jig on aligment system
ASPIC Packaging: Optical alignment equipment
• Main features:
Automated alignment bench with nanometrics resolution
Up to 16 motorized axis
Laser welding and UV epoxy fixing capability
ASPIC Packaging: Optical alignment process
•
Comparision between lensed and bare fiber (area scan)
ASPIC Packaging: Lensed Fiber alignment process
•
Defocussing examples with lensed fiber
Line scan H/V at max coupling position
moving fiber 10um and 20um far from
max
Line scan H/V at max coupling
position Line scan along optical axis
+/- 10 um
ASPIC Packaging: Lensed Fiber alignment process
• Lensed fiber alignment details
ASPIC Package: Angled chip Package layout
• Angled chip 6x2mm size
ASPIC Package: Straight chip Package layout
• Straight chip 6X6mm size
ASPIC Package: Package layout
© Linkra s.r.l
ASPIC Package: Samples Delivery
© Linkra s.r.l