The document discusses trends in product creation processes towards shorter development times, higher integration, and more stringent quality demands. It emphasizes the importance of evaluating modules through environmental stress testing like HALT before system integration to ensure reliability in the intended system environment which can subject modules to heat, shock, vibration and other stresses. The results of HALT testing are presented as a case study that identified design flaws and led to modifications to improve the design margin and reliability of integrated systems.

1. From modular design to System
Integration
15 June 2010
ray.brett@philips.com

2. Contents
 Trends in Product Creation process
 System reliability
 Module Pro-active evaluation before integration
 System environments
 System environments and module immunity
 Arrhenius law and cooling
 HALT testing and case overview
 Temperature
 Transients (EFT)
 Shock & Vibration
 Conclusion
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3. Trends in Product Creation Processes
 Time: Shorter time to market (profitability)
 Costs: Cost competitiveness
 Function: Higher level of integration
 Development:
– COTS (Commercial Off-The-Shelf) modules
– Black-box module developments
 Quality: Increasing customer demands
Customer expects:
Maximum up-time
Maximum performance
Not according to expectations Present
Not according to specifications
Future
Safety (liability)
3

4. System reliability
“A chain is only as strong as its weakest link" applies to
any process that will fail if some step in it goes wrong.
Problem:
How to ensure that the system will perform as intended
and will work reliably throughout it’s (intended) lifecycle -
after various modules have been integrated?
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5. Module Pro-active evaluation before integration
ModuleTesting involves checking that the module performs
according to its specifications.
However, before system integration, extra environmental
stress-testing (such as HALT) can ensure that they will
function reliably in their intended system environment.
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6. System Environment
A “System Environment” is not a “laboratory environment”. Instead, it is
usually rugged and modules can be exposed to various phenomena such as:
– Heat : 35C environment temperature can be common in some geographical areas and
can cause much higher temperatures in modules behind covers.
– Shock & Vibration – depending on the machine type but also take into account transport
and installation (dropping/bumping).
– Electromagnetic noise (intra machine compatibility)
– Other phenomena includes:
– Pluggable “Module hot swapping” (this can be common)
– Inrush currents
– Grounding
– Crosstalk
– EMC and Safety (Regulatory requirements)
– Other 6

7. System Environment & module immunity
 The system architecture should be designed such that its environment
is kept as “friendly” as possible as far as electronics is concerned.
– This involves:
• Cooling considerations Increase
Design
• Reduction of mechanical stresses Margin
• Reduction of electromagnetic phenomena
– Inrush; ESD; Crosstalk etc.
System environment Module immunity
 Modules should be designed/selected so that they can withstand the
harsh environments in which they can be exposed.
 This can create a margin between possible environmental stresses and
higher module immunity levels, giving longer life expectancy.
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8. Arrhenius law in lifetime acceleration for electronics
Tacc =exp[(Ea/k)*(1/Ta - 1/T)]
Thermal acceleration of failure rate
1.0E-01
Factor 811
Factor 452
1.0E-02
Factor 244
Reaction rate
Factor 127
1.0E-03
Factor 31
Factor 6 Ea = 0.72
1.0E-04
K = Boltzmann’s constant
Factor 2,6
T = Kelvin
1.0E-05
20 40 60 80 100 120 140 160
Temperature oC 8

9. Cooling
Keeping electronics cool is essential for system
MTBF performance.
An overview should be made of the module heat
dissipations for optimum placement & air-flow.
MDU: 180 W
Trafo : 180 W
Power supplies:
X&Y-motors: 328 W Transport
4x290 W = 1160 W controller B:
(Not shown) 55 W
-- XY Drive:
260 W
System
controller: Transport
180 W Ethernet controller A:
switch: 55 W
25 W Source: Siemens
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10. HALT
 “A chain is only as strong as its weakest link" applies to any process
that will fail if some step in it goes wrong.
 HALT (High Accelerated Life Testing) can be useful in identifying such
"weak links" before system integration/Total Test. Consequently design
margins can be increased to improve system reliability.
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11. What is HALT ?
 HALT is an engineering step-stress-to-fail process which can reveal
design flaws quickly (within hours of testing).
 HALT is not a compliance test and not limited by component or product
specifications.
Failure
Evaluate the relevance of the failure.
Determine if stress-level is acceptible and
implement corrective action if necessary.
Failure
Specification (max.)
Evaluate the relevance of the failure.
Determine if stress-level is acceptible and
implement corrective action if necessary.
Increase stress
Apply stress
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(10-15min)

12. HALT tests may include:
 Temperature
• (-40oC to 140oC) under max. loading conditions
• In combination with power cycling (ON/OFF)
 Temperature cycling
 Voltage (in combination with temp.)
 Electric transient susceptibility (all cables)
 Shock & vibration
 RH%
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13. HALT case overview – Temperature
Modified Modified Modified Modified Modified Modified Modified
Change res. values Change FET type Change IC type Change Diode type Change FET type Change the BIOS settings. 2 x pull-down
Cost: negligible Cost: approx. 10ct Cost: approx. 10ct Cost: approx. 5ct Add 10uF capacitor Cost: negligible resistors.
Cost approx. 20ct (Implementation) Cost: negligible
+140C
140C 140C 140C 140C 140C
130C X20 PCB’s 130C X14 PCBs 2nd Failure
Case 6
120C (ITBF-EFT)
Case 1
(Tape
cutter)
+100C 100C
100C
85C
80C Modified
X20PCB’s 80C 80C
Solve in FPGA
Cost: negligible
70C 70C 70C
Case 2 Case 3
(PCU- (PCU-IC)
FETs) 60C
Case 4 Case 10
Case 5 (PHs2)
+50C (PCU- (re-use F)
diode)
Case 7 Case 9
(TPR Lift
-10C (BA-Camera)
controller) Sprocket
detector
Case 8 Power
(AXPC) cycling
-40C
Re-active (learning – correlation with FP’s) Pro-active 13

14. Summary: Performing Temperature HALT
 For HALT; (Rule of Thumb): ensure a margin of at least 40C above
specification.
• (This is NOT a continuous spec!)
 It’s important to analyze all failures and to decide on:
• Root cause
• Evaluate the relevance of the failure
• What is the effort/cost for improvement
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15. Electric transients (EFT)
 Electronic circuits with cable connections are prone to electric transients.
 Cables can be excellent antenna’s, depending on impedances, length etc. and can
pick up such transients:
 This phenomenon deals with intra-EMC immunity, NOT EMC-Directive
15

16. Example of an electric transient and effects
Relay switching off a load with
a residue voltage.
Possible resultant damage caused by
Possible resultant transient voltage a transient voltage disturbance.
which can be induced into nearby
cables or locally on a PCB.
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17. HALT case overview – Transients (EFT)
Modified Modified Modified Modified Modified Design integration
Add 10nF cap. Gnd. connection Add 2x10nF caps. Shield repeater Gnd. connection EMC
Cost: negligible Cost: negligible Cost: negligible Cost: 5 euro Cost: 10ct Cost: negligible
10kV
10kV 10kV 10kV
Case 8
9kV (TPR)
At approx. 8kV, 8kV
8kV
Cable isolation gets “tricky” 8kV
defect
Design integration
7kV EMC
Cost: negligible
6kV
6kV Case 6
(BA-
Camera)
5kV
Case 3 Case 4 Case 7
(Tape cutter) Fire-Wire (LED pcb)
mP reset Repeater
4kV 4kV
3kV 3kV 3kV Case 5 2.8kV
2.5kV (Sprocket
detector)
2kV Case 1 2kV
Case 2
3kV 2kV
(ITBF) 1.5kV
mP reset defect 1kV
1kV FET defect
0.5kV 0.6kV
Re-active (learning – correlation with FP’s) Pro-active 17

18. Transient “Rule of thumb” HALT targets
 “Hard failure” (>4kV)
• A Hard failure can be either a H/W defect or a catastrophic S/W error.
• A catastrophic S/W error could involve restarting an application after a
“freeze-up”.
• A H/W defect could involve a defect component.
 “Soft” error: (>2kV)
• A soft error usually involves a software failure but may not affect the
system in any serious manner.
– E.g. a sub-system/system “hiccup” which is self recoverable.
– A certain amount of immunity is needed because too many “hiccups”
may affect machine throughput.
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19. System environment (Shock & Vibration)
 The relationship between shock & vibration and module lifetime.
– Example: Servo controls placed on robot placement heads
– Up to now we have custom-made products where we apply
stringent shock & vibration requirements.
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20. Shock & Vibration
 Early involvement of the behaviour of the electrical, mechanical
and optical BA Fumo design during shock and vibration.
 Trace the problems before re-design
 Focus on
– reliability of electrical boards and connections
– reliability optical mountings
– reliability of mechanical attachements
 During operation and transport
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21. Example
PHSx-O
Representing Optics PHSx-E
Representing Electronics
For HALT; (Rule of Thumb): ensure a margin of at least a factor of 2 above spec. 21

22. Conclusion
• A “System Environment” is not a “laboratory environment”. It can be rugged and system
modules should be stressed under test conditions which can occur within its system:
• Creating a higher margin between possible environmental stresses and module immunity
levels will give a longer life expectancy.
• HALT can be a very effective tool for achieving higher module immunity levels before
system integration.
• Unfortunately, most subcontractors are not familiar with HALT and see it as a cost driver.
• Regarding COTS modules, HALT can also reveal potential failures but implementing
possible design improvements may involve cooperation from suppliers.
• Unfortunately, (more often than not), this does not lead to the desired result. In practice, HALT
is often not fully understood and is seen as a cost driver.
• Nevertheless, knowing your weak-spots before system integration can give a leading edge (if
module improvement cannot be made, system adaptation may be an option).
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23. Questions
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