1. IAPP week@CERN – training day 20.07.2016
TE-MPE-EM
IAPP – training day
Electronic assembly challenges
Sylvain Kaufmann
TE-MPE-EM electronic assembly workshop process engineer
TE-MPE-EM design office technical support for assembly related matters
Welcome
Introduce TE-MPE-EM and myself
IAPP_week_at_CERN_training_ pptx
S. Kaufmann

2. TOC TE-MPE-EM SOME BASICS UNRELIABILITY AT CERN SEEN FROM TE-MPE-EM
Practical case: poor outsourcing practices
Poor design practices: BGA designs example
Poor parts handling/packaging: some examples
HOW TO IMPROVE
Design for excellence
First slides -> stating the obvious
Followed by one practical case illustrating unreliability due to poor outsourcing practices -> only real generic case everyone can learn from
Poor practices -> poor design example and parts procurement example
Best practices -> standards, design for excellence, outsourcing, parts procurment
Conclusion
Questions
Outsourcing
Parts procurement
CONCLUSION
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3. SOME BASICS Reliability versus quality
TE-MPE-EM
SOME BASICS
Reliability versus quality
Nowadays too often both terms are considered or used as synonymous
However these are two different disciplines even if they are related to each other
Today common accepted definitions are:
« Quality is conformance to customer expectation »
Supported by specifications, QA activities/tools
Involves everyone related to the product (design, manufacturing, purchase office, etc)
Reliability VS quality
« Reliability is quality over time »
Supported by design, project management, quality assurance
Involves design team and project management
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4. SOME BASICS Failure in electronics: quality, the usual suspect
TE-MPE-EM
SOME BASICS
Failure in electronics: quality, the usual suspect
Provided that most of the failures (approx. 90%) in electronics are due to solder joint defects, quality is regulary seen as the primary suspect
However, even if proper quality management helps increasing yield, it is often the combination of several of the following factors
Design
Outsourcing practices
Assembly practices by the sub-contractor
Parts procurement
Assembled board handling
Quality usually hides design as the real reliability killer
Also, it is important to understand that quality will never increase reliability that was built in the design
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5. Assembly: the quality and reliability revelator
TE-MPE-EM
SOME BASICS
Assembly: the quality and reliability revelator
In the majority of the cases, except special dedicated cases, electronic assembly is the lowest added value process for the product with respect to design and/or part procurement costs
At the same time, assembly is the process where all the previous quality efforts can very quickly be vanished
This can induce unnacceptable delays and costs that can eventually completely kill a project, even before a single production board is tested
Assembly:
- less added value in process, but principle parts killer
- final step and moment where all pieces are put together. If a quality issue passed previous filters, it will be revealed here.
No need to say that extreme care must be taken when selecting the assembly company
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6. Parts, PCB and material manufacturers: wrong common belief
TE-MPE-EM
SOME BASICS
Parts, PCB and material manufacturers: wrong common belief
The highest scored wrong common belief justifying an unpredicted result occuring due to incompatible practices is:
« They should have known this was not compatible, they all work in the electronics business »
No, even if everybody works in the electronics business, don’t assume that every actor understands the activities of others, it is very rarely the case
The project team must be the one that understands electronic manufacturing/assembly constraints and gives directions to all involved parties
No, electronics industry actors does not necessary sit together at a table to define strategies
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7. Unreliability top scorers: TE-MPE-EM experience
UNRELIABILITY AT CERN
Unreliability top scorers: TE-MPE-EM experience
1° Poor outsourcing practices:
- Lack of or unadapted technical documentation
- Wrong company selection
2° Poor design practices:
- Lack of manufacturing/assembly constraints knowledge
- Material incompatibility or lack of material contraints knowledge
- Lack of reliability principles understanding/knowledge
Reliability killers at CERN, the usual cases
3° Parts procurement:
- Poor parts packaging, storing and handling practices
- Second hand and couterfeit parts
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8. Does this board look like rocket science?
TE-MPE-EM
UNRELIABILITY AT CERN
Practical case: poor outsourcing practices
Does this board look like rocket science?
Double-sided SMD
1 CoB (chip on board)
2 connectors
12 resistors/capacitors
600+ boards
50% yield due to PCB delamination
Practical case: outsourcing nightmare story
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9. Practical case: poor outsourcing practices
TE-MPE-EM
UNRELIABILITY AT CERN
Practical case: poor outsourcing practices
Project description:
PCB assembly combining standard SMD and CoB
> 600 pieces to be assembled by an external company
PCB stackup using mixed materials (FR4 internal, Polyimide external)
Quality issue: PCB delamination due to moisture absorption by the base material
Solution: bake the boards prior to soldering processes
Sequence of events:
- A pilot validation production of few pieces was requested by the project team
- Inspection of the pilot production showed delamination on PCBs
- Analysis showed it was due to lack of baking of the PCBs prior to soldering processes
- Company agreed to bake the PCBs prior to soldering processes
- A new pilot production was built not showing any defects
- The production run, when delivered, exhibited the same yield and quality issue as on first pilot production
Practical case: outsourcing nightmare story
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10. Practical case: poor outsourcing practices
TE-MPE-EM
UNRELIABILITY AT CERN
Practical case: poor outsourcing practices
So… What happened?
The company, as planned, baked the boards prior to soldering
Unfortunately, they soldered the first side one day and soldered the second side the day after
The time between PCB baking and the second soldering process was long enough to allow a complete moisture absorbtion by the PCB
How come that the company did not realize a second baking was required?
First, obviously the company does not understand material moisture absorption processes
and
The project team assumed « the company have the understanding and knowledge of PCB materials, and thus will handle the boards properly once warned about the special stackup and guidelines are given »
Practical case: outsourcing nightmare story
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11. Practical case: poor outsourcing practices
TE-MPE-EM
UNRELIABILITY AT CERN
Practical case: poor outsourcing practices
So… Then?
Of course, the failed boards (50%) had to be trashed and unacceptable delays and added costs entered the project
The company refused refunding of PCBs and parts considering they were not properly informed about the required special handling
Epilogue
The situation then generated a lot of discussions back and forth between CERN and the subcontractor
The discussion with the subcontractor could have been shortened if the proper specification would have been part of the order
Practical case: outsourcing nightmare story
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12. Poor design practices: some examples
TE-MPE-EM
UNRELIABILITY AT CERN
Poor design practices: some examples
BGA design classics
BGA design classics: pad geometry, vias, location on board
Every ball shall have an individual pad with the same shape, except on certain occasions for reliability improvement
Vias close to BGA pads shall be tented to avoid solder wicking inside it and thus ensure homogene solder volume in joints
IAPP_week_at_CERN_training_ pptx
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13. Poor design practices: some examples
TE-MPE-EM
UNRELIABILITY AT CERN
Poor design practices: some examples
BGA design classics
BGA design classics: pad geometry, vias, location on board
Mechanical attachement like screws shall be put away from BGA parts to avoid unnecessary load on solder joints
BGA parts should not be put in the middle of the board as it is where the max deflection will occur
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14. UNRELIABILITY AT CERN Poor design practices: some examples TE-MPE-EM
QFN design : NINO chip (CERN ASIC)
BGA design classics: pad geometry, vias, location on board
No soldermask between pads, common signals becoming a single pad, ground/thermal pad not centered
Everything is wrong in this design inducing both quality and reliability issues
Soldermask between pads, one pad per individual signal, ground/thermal pad centered
Proper design improving quality and reliability
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15. Poor design practices: chose the right fit
TE-MPE-EM
UNRELIABILITY AT CERN
Poor design practices: chose the right fit
1206 Chip
0805 Chip
0603 Chip
0402 Chip
0201 Chip
0.4mm soldering tip
NINO
BGA design classics: pad geometry, vias, location on board
0.3mm solderwire
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16. UNRELIABILITY AT CERN Poor parts handling/packaging: some examples
TE-MPE-EM
UNRELIABILITY AT CERN
Poor parts handling/packaging: some examples
Some parts for an outsourced production…
Parts packaging: no comment
IAPP_week_at_CERN_training_ pptx
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17. UNRELIABILITY AT CERN Poor parts handling/packaging: some examples
TE-MPE-EM
UNRELIABILITY AT CERN
Poor parts handling/packaging: some examples
Some boards for modification or repair operations…
Boards packaging: no comment
IAPP_week_at_CERN_training_ pptx
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18. Design base line: IPC/JEDEC standards
TE-MPE-EM
HOW TO IMPROVE
Design base line: IPC/JEDEC standards
Regarding design, the very first reference to look at is IPC/JEDEC standards
IPC is nowaday the first ressource for industry regarding standards applicable to electronics DfM (design for manufacturing)
Applicable standards are numerous, here are some examples (see IPC website for details, ipc.org):
- IPC-2220 serie -> board design
- IPC > land pattern design
- IPC-J-STD-001 -> soldering requirements
- etc
IPC: design base line
IMPORTANT NOTICE: those standards represents the MINIMUM requirements, some projects may require to adapt the standards in order to get the expected reliability
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19. HOW TO IMPROVE Apply known and proven techniques to project management
TE-MPE-EM
HOW TO IMPROVE
Apply known and proven techniques to project management
Design for excellence techniques
Design for reliability
Design for manufacturing
Design for sourcing
Design for excellence: the only solution to save costs and really improve project success chances
This is an internal process that cannot be outsourced and that must be sutained by project management, a designer cannot succeed alone on such initiatives, this is a team work
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20. Apply known and proven techniques to project management
TE-MPE-EM
HOW TO IMPROVE
Apply known and proven techniques to project management
Design for excellence combines lots of different standards and tools like:
- IPC/JEDEC standards
- LEAN techniques (applied to supply chain)
- Design review additional stages (requesting external input from manufacturing and assembly engineers for example)
- etc
Where to find information about DfX:
- Several multi-days seminars are available in the world (IPC, SMTA, SMART)
- Some literature is available on the subject
- Consulting companies provide on-site seminars (one was organized at CERN in 2010)
DfX: what and where to find information
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21. An electronic engineer is not a layout engineer
TE-MPE-EM
HOW TO IMPROVE
An electronic engineer is not a layout engineer
One common mistake from project management is thinking that electronic design and layout design could be handled by the same person
It is not true. The electronic engineer deals with electronic functions/response times/signal integrity (electronics), while the layout engineer deals with manufacturability/assembly/testability/repairability (mechanical)
Both these designers should work hand in hand in order to succeed with the project
The experience in the assembly field teaches that there is little chance to have a person able to combine full experience and skill in both disciplines
Electronic designer VS layout designer
In electronic design, don’t underestimate the things you don’t know and that you are not aware of not knowing it
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22. Outsourcing: the big deal
TE-MPE-EM
HOW TO IMPROVE
Outsourcing: the big deal
As stated some slides above, outsourcing can vanish all your design efforts when not properly handled
The proper company shall be selected following proper auditing:
- Production capacity AND capability
- Process control
- Internal quality management
- Internal problem solving processes and availability of required experts
- etc
Finally the company should be given with dedicated specifications for assembly
Outsourcing, no rocket science here
However, soldering remains a « non visual inspection assessable » process, sole destructive analysis can give answers when things goes wrong
Soldering electronic boards is not an easy deal and it requires a lot of proactive work and different knowledges in order to reach the required quality and succeed with todays constraints
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23. Building « out of standards » electronics
TE-MPE-EM
HOW TO IMPROVE
Building « out of standards » electronics
The case of inner detector electronics requires a special comment
This electronics usually deal with very specific materials and parts due to the necessity to be as transparent as possible to particles observed
And of course, provided they are inside the detector, they must work for more than 15 years
No choice but one: involve the manufacturer and assembler in the very first stages of design as they will be the only ones who can help with yield on such specific needs
In addition, for those specific boards, reliability shall be demonstrated
Out of standard electronics require specific actions – these actions are mandatory
IAPP_week_at_CERN_training_ pptx
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24. Parts procurement: trusted vendors for production runs
TE-MPE-EM
HOW TO IMPROVE
Parts procurement: trusted vendors for production runs
One regular quality killer TE-MPE-EM faces when outsourcing products for our customers is part packaging and sourcing
For production runs, only trusted vendors shall be contacted when parts are required and packaging should be carefully handled to cope with production needs
Working with trusted vendors limits the risk of receiving conterfeit parts or poorly handled and packaged parts
General purpose electronic distributors as well as so-called brokers should be considered only when no other choices are available for parts procurement
Trusted vendors vs CERN store
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25. Built-in reliability is key to success
TE-MPE-EM
CONCLUSION
Built-in reliability is key to success
If a project team wants to plan ahead in the development with regard to reliability, design should have the reliability « built-in »
In order to get there, the whole project team must support actions: design for reliability requires extra ressources during early design stages – however the related costs will allways be far less than problem fixing costs
Design for excellence (or reliability) requires know-how of course, but most importantly it requires field data collection, proper analysis and project organization-wide rules and methodologies – this requires some time to implement, it is not a straight forward process
Reliability is an internal policy and requires to be built in design to succeed
Prior to become knowledge and techniques, reliability is an internal policy
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26. Industry provides good things, but…
TE-MPE-EM
CONCLUSION
Industry provides good things, but…
Sometimes industry proposes solutions that don’t necessary follow the best rules for reliability, usually for financial reasons – leadless packages becoming the standard for IC packages is a pretty good example of this trend
Due to economical situation a lot of outsourcing companies have lost their experts in soldering techniques – in best cases, the process technician is still in place and in worst cases the line manager plays the double role
The above situation becomes critical when problem solving must be deployed as the required knowledge is not there anymore
The good news is that some of those experts are still available, they now propose consulting services to industry (with the related costs one can easily imagine)
Industry is not always good and should not be used as benchmark for CERN
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27. THANK YOU FOR YOUR KIND ATTENTION QUESTIONS?
TE-MPE-EM
THANK YOU FOR YOUR KIND ATTENTION
QUESTIONS?
Thanks
Questions?
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S. Kaufmann