RE>GEN: Advice on Process Control            4/24/96

Moss,

Doug Pauls made some excellent points, and I would like to add a few things.  I spent many years in a materials analysis capacity, as well as in my current mfg eng capacity, so I believe I've seen both sides of this particular street.

A few points:
1) I believe that distinctions need to be made between process *development*, process *monitoring*, and process *failure analysis* tests.  Tests for one may or may not be appropriate for another.  It has been my experience that many lab folks tend to not make this distinction and wind up using inappropriate tests.  Many times a test is done simply because it *can* be done, rather than whether it will show anything or not.  

2) The use of the term "required tests" is interesting.  Who requires the tests?  What specifically is being required?  Although I greatly respect the time and energy that many individuals have spent to come up with standardized tests for the industry, I've found some tests to not be that worthwhile and have developed more suitable alternatives for specific applications.  The challenge that an independent lab would most likely face would be performing both standardized and custom tests -- flexibility!

3) Companies are generally much more conservative now with respect to developing assembly technology.  The constriction of many companies in the late 80s and early 90s no doubt contributed to this.  Companies concentrate more on either improving processes in place or gradually, incrementally increasing process capability.  I contrast this with some neat developmental projects that I worked on 10 years ago (TAB, liquid nitrogen cooled processors, surface mount PGAs); the gradual maturation of assembly technology and greater accumulated field reliability database has helped to show which process monitoring tests are worthwhile and which aren't.  

I hope that these comments help!

Greg Bartlett
Mercury Computer Systems
Chelmsford, MA
[log in to unmask]

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If I can have a moment of your time, I would like to ask for your opinion on 
materials analysis in electronics manufacturing.
I work with AMT Ireland in the Interconnect service. We offer a wide range 
of materials analysis tests and consultancy with a large proportion of 
electronics companies in Ireland. I have experienced that our service is 
 required by Process Engineers and Manufacturing Engineers who wait for the 
problem to arise on their PCB assembly.
We offer prompt attention to companies who panic in the face of emerging 
defects and perform the required tests in our Electronics Manufacturing 
Centre.
The main tests include;
SIR testing
Ionic Contamination testing
Electromigration testing
Microsectioning
Flux corrosivity testing
etc
which are all implemented into helping develop new processes, such as 
No-Clean, Paste Evaluation, Cleanliness, BGA Analysis etc

I would appreciate if you could forward your opinion on whether companies 
should monitor key elements within the process on a continuous basis instead 
of waiting for the defect to occur before taking action.
Are companies ignoring the importance of such process monitoring tools in 
your experience?
We have a few companies who control their process using our services. Why in 
your mind are the rest  not?
Would the downtime in production be significantly decreased if process 
checks were carried out on a continuous basis.

Any comments and opinions are  much appreciated,

Thanks in advance,

Regards,
Moss Dore           
                    Phone:    353-61-331588
AMT Ireland              Fax: 353-61-330316
Electronics Manufacturing Centre   Email:    [log in to unmask]
University of Limerick
National Technological Park
Limerick