APE Rework Principles
Advanced Programming in
Vision Rework
Features of APE Technology
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Convection Hot Air
Flexible Segment Profiling
Open Oven Nozzle Design
Component Inspection after Placement and prior
to Reflow
“Real Time” Profile Development
Optimum Power Performance
Optimum Low Velocity – High Volume Air Flow
Thermocouple Profile Development
Superior Vision and Component Viewing
Robust Design
Advantages of APE Hot Air
Technology
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Hot Air Convection replicates the original Oven Manufacturing Profile and
environment (Up to 16 Zones/Segments).
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Safe Lower Temperatures due to Heater and delivery design resulting in
improved Power, Low velocity and High Volume Air Flow.
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Extended Heater life.
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Placement and Reflow is separated allowing installation of larger Heaters
with greater Air Volume.
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Separating the Placement and Reflow stations enables inspection of the
component after Placement and prior to Reflow.
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An open Nozzle design provides an improved Temperature Delta across
component and PCB and can rework components in tight proximity.
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PID Step Profile Development allows greater flexibility in ramp-soak profile
design as opposed to Zone Profiling.
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Convection Under Board Heating can be operated simultaneously with Top
Reflow Heater from the First Segment.
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Extremely Robust and Long Life Technology with Low Running Costs
Single Station Versus Dual Station
Machines
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Placement and Reflow:
A number of Rework machines Place and Reflow in the same location – at first glance
this appears to be an advantage but it has the disadvantage of forcing a smaller
Heater design resulting in Lower Air Volume and a Higher Air Velocity, which creates
greater turbulence to and around the component.
Recently APE’s (patented) higher Power methodology has been generally adopted in
the industry to address Lead-Free demands. Heaters are commonly running at
greater than a 1000 Watts in a confined chamber with the result that they burn out
at a rapid rate – often at a frequency of one Heater per month. This single station
concept is contrary to an APE Dual Station principle that not only allows a Heater
design with a High Power Element but also provides for a Heater with an “HIGHER
VOLUME” and “LOWER VELOCITY” Air Flow. This is only possible when a
Placement and Reflow Station is separated. It is unusual for an APE Heater to burn
out within 12 months of continuous use.
Single Station Rework versus Dual Station Rework:
With a single station system the board remains stationary – this is again seen as an
advantage but in practice the restricted Heater design coupled with the inability to
view the component after Placement is a far greater disadvantage than the smooth
transition from Placement to Reflow with an APE system.
Comparison of APE Hot Air
Technology with Competition
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Open Oven Nozzle RAMP-SOAK Profile Development versus Closed Nozzle
Zone Ramping :
There are three target Temperature Zones of importance when creating a
Temperature Pattern or Profile:
Example - Eutectic Reflow Temperature 183C (Time above 30 – 90 seconds)
Board Expansion (90C)
Flux Activation (150 - 160C)
Peak Solder Temperature (221C+/- 10%
A number of Closed Nozzle systems divide these targets into three zones, triggering
the profile progress through each zone. In most cases the first zone is a Pre-Heat
stage (90C) which triggers the second zone for flux activation and so on to the last
Reflow zone. There is no soaking in this method and prevents the Under Board
Heater being used in conjunction with the Top Heater. Running both Heaters from the
start of the Heat Cycle is a far better way of reducing the Delta T.
The method also prevents the flexibility that is seen in a Multiple Zone Convection
Reflow Oven and an APE Rework machine, both of which allow for RAMP SOAK
profiling not just Temperature Ramping in three zones. A typical APE profile is 7-8
zones or segments to accomplish a Pattern or Profile.
Creating a Temperature Profile
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Profiling “Real Time” or “On The Fly:”
This coined phrase is interesting as Zone Profiling has difficulty in achieving it. When
dragging a Temperature Bar to enable solder temperature to reach the air zone
temperature, it is characteristic of the software that only the target temperature bar
is lengthened – it does not enable the programmer to track the temperature waypoints prior to the change. Thus it is not an accurate “On The Fly” method. With APE
software and Multiple Segment Programming, tracking the temperature way-points is
possible and an accurate Profile can be created in Real Time.
Note: Having the ability to profile “On the Fly” is no substitute for an
analytical study of a profile behavior and introducing that study to a new
Profile-Pattern starting from an ambient temperature.
When selecting the APE “Real Time” feature in the graphical view, the segment of
Time and Soak is simply put on “HOLD,” until the solder temperature achieves the
target. The segment is then released and the “HOLD” process repeated through the
segments until the Peak Solder Temperature is achieved. The Programmer then
simply retraces the Time and Temperature segments selected in the Real Time profile
noting the changed intervals and adjusting the original pattern segments and
uploading these values to create the new recipe on the Sniper On-Board-Computer.
The method is the same for Eutectic or Lead-Free Temperatures Profiles.
Typical Eutectic Profile
Typical Reflow Profile
300
Temperature
250
200
Air Temperature
150
Solder Temperature
100
SN63/37 Solder Melt Point 361F
50
0
0:00
:30
1:00
:31
2:00
:32
3:00
:33
4:00
:34
5:00
:35
Air Temperature
26
90
90
90
150
175
175
250
250
250
150
90
Solder Temperature
26
SN63/37 Solder Melt Point 361F 183
6:00
45
67
89
95
135
151
183
205
215
180
120
75
183
183
183
183
183
183
183
183
183
183
183
183
Time
Open Versus Closed Nozzle
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Convection Rework machines either use a Closed Nozzle or an Open Nozzle principle,
which APE refers to as an “Open Oven Nozzle.”
The Closed Nozzle design evolved from the early introduction of SMD QFP components
where focused heat was mistakenly thought to be the key element in rework, reflowing
the leads only to avoid heating the component body and die. With the advent of BGA’s
this was not possible and the nozzles were modified to heat the entire component not
just the leads, but the Closed Nozzle concept remained.
This was acceptable as long as components were large and there was sufficient room
around each component to accept a nozzle that would completely enclose and seal the
component being reworked. Because these Closed Nozzle systems Place and Reflow in
one position the heaters were mounted in a confined space consequentially reducing
the air volume and necessitating an adjustable higher air velocity.
Twenty years have passed and three important factors now make this design
impractical and redundant: 1. Heater Power increased from a typical 800 Watts to
>1200 watts to cope with Lead Free solder. 2. Components reduced in size and 3.
Components became tightly packed around each other.
The Closed Nozzles higher velocity can disturb the subject. With tightly packed
components the nozzle can no longer seal the component. The air temperature is
hotter and can scorch, it also increases the Delta T in the PCB so that Under Board
heating is critical.
With an APE Open Oven Nozzle design all these disadvantages are eliminated – AND –
in conclusion Closed Nozzles are now sometimes used in a similar way to Open
Nozzles BUT the Higher Velocity and Lower Air Volume of the design make it an
ineffectual medium that can also disturb adjacent components.
APE Hot Air Convection versus IR
Today there are few
installations of IR Reflow
Ovens used in the
assembly of PCB’s within
the Electronics Industry !
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Convection versus IR
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The previous statement should prompt the question as to why?
The answer to this question is pertinent as to whether IR is also a suitable method
for Reworking, having agreed that a RAMP SOAK method of convection reflow is
preferred by an OEM in manufacture.
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An IR BEAM is not a LASER!
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An obvious statement? Not so – many engineers are confused by the two light
technologies and confuse IR with a laser.
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Lasers are straight line beams. IR is like a torch light – the further the distance off –
the wider the beam – therefore the distance from Target is so critical that it’s rarely
repeatable.
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IR targets the component or the leads – not the surrounding air – the Temperature
Delta must therefore be much wider than a Hot Air Convection Method.
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The IR sensor is not in the centre of the beam – where is it? – It’s difficult to
calculate and will change with distance off.
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IR is sensitive to component coloring – this statement is as true now as it has always
been.
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The sensor can only visually target the outside lead of a BGA and it must be focused.
Camera and Sensor on the lead – with a CSP this is difficult and of course it’s
impossible to focus on a centre sphere.
Lead-Free Rework
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All APE Rework machines having an APE bottom heater are suitable for Lead-Free
rework tasks and are therefore Lead-Free compliant. But – only a Vision-Rework
machine is suitable for BGA and CSP components due to limited surface tension
characteristics with Lead-Free materials.
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Detailed below is a typical Lead-Free material:
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Reflow Temperature 221C Time above Reflow Temperature 60 – 120 seconds
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Board Expansion (90C) Unchanged.
Flux Activation (150 - 160C) Unchanged.
Peak Solder Temperature (242 - 245C)
The air temperature must obviously be run hotter to reflow, however by raising the
bottom heater and having an APE open nozzle design the top reflow temperature can
be kept below that which might otherwise be harmful by a variance in Delta T and
degradation or catastrophic damage to adjacent components.
Notice also that the time above Reflow Temperature is significantly longer than
eutectic.
Typical APE Rework Lead Free Process
This is an example of a lead free reflow process in use at a Cellular OEM
Typical APE Rework Lead-Free Process
Parameters:
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Solder characteristics: (formulation confidential)
Solder melt: 430F (221C)
Peak solder temp requirement: 468F to 473F (242C to 245C)
Time above 430F: 60 seconds minimum.
***Notice: Considerably higher reflow temperature +69F (21C)
deg over SN63/37
Time requirement above reflow temperature is longer than typical.
Typically 45-90 seconds, now 60 – 120 seconds
Component Characteristics:
14mm uBGA, 282 count, 18mil pitch
Max Temperature 482F (250C)
Max Ramp Rate 4.5F/ sec (2.5C/sec)
***Notice: Even smaller pitch for this part <.5mm
Component mass is such that solder temperature can be
considered as an accurate scale of component core temperature.
Typical APE Rework Lead-Free Process
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PCB Description:
Small high-density test board with multiple BGA and CSP devices and high count
plastic connectors.
5” x 5” area, 3mm Thickness, 7 Layers with one full ground plane and 108 grams in
weight as an assembly.
Machine used:
A.P.E. South - Sniper I with R0028A Controllers
Reflow Controller
Profile: SV=560F (293C)
Ramp: 1:30 (Time)
Adder function OFF
Total run time: 2:45
Preheat Controller
Profile: SV=410F (210C)
Ramp: 1:30
***Notice:
Higher set points for both bottom and topside heaters than we are
typically used to, such as top 450F (232C), bottom 325F (163C), now 560F (293C)
and 410F (210C) respectively in this example..
Results: See graph.
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Peak Solder Temp 472F (244C)
Time above 430F (221C) 1:21
Ramp rate at solder/component body 3.9F/sec (2.2C/sec)
Section Through Lead-Free
Process
Sample APE Clients include:
Memory Manufacturers:
Communications:
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Kingston Technology
Corsair Memory
SimpleTech
ATP Systems
PNY Technologies
PDP Systems
PC Partner
Motorola
Samsung
Kyocera
Qualcom
Nokia
Siemens
Nortel
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Contractors:
Computers & Components
Solectron
Celestica
Jabal Circuits
Intel
IBM
Nvidea
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Security/Defense:
US Naval Weapons
US Home Land Security
US Army
NSA
FBI
Lockheed
Harris
APE New Vision Series
Sniper III
Intruder Lightning
Liberty Sharpshooter 220V
Sniper Wide Body
www.ape.com
APE manufacturing situated at:
APE House
North Blackwater Lane
Key Largo
Florida, USA 33037
Tel: 305-451-4722
Fax: 305-451-3374
Email: sales@ape.com
Web Site www.ape.com