The evolution of compatibility

Citation

(1999), "The evolution of compatibility", Circuit World, Vol. 25 No. 4. https://doi.org/10.1108/cw.1999.21725dab.020

The evolution of compatibility

The evolution of compatibility

Keywords: Concoat, Standards, NPL

Manufacturing the average electronic circuit assembly involves at least 12 different chemical processes. How these process chemistries inter-react with one another has become a major quality and reliability issue as electronic circuits increasingly employ fine-line, fine pitch; SMT and modern chip-scale packaging; use higher impedances or operating frequencies and are more commonly located in hostile operating environments. This, coupled with the high incidence of "No-clean" processing methods, has caused greater concerns about the synergy between these materials and how they may influence electronic circuit reliability.

According to the National Physical Laboratory (NPL), this is a major, if not widely, recognised problem and Concoat are closely involved with the NPL with respect to the development of new industry standards.

It was through involvement with earlier NPL programmes and the development of the Auto-SIR™ Circuit Reliability Test System, that the synergie™ material range has evolved.

Synergie™ is a range of process chemistries that have been or are being tested, in order to minimise these compatibility issues. It is a never ending process because the matrix is so large and there are so many process variables. The test method we have used is ANSI/IPC JSTD-001B including Appendix D relating to Process Characterisation. This involves SIR testing but we have gone a stage further, by using our Auto-SIR™ and Frequent Monitoring Trend Analysis (FMTA).

Auto-SIR™ FMTA permits the test intervals to be reduced from the present specified "once per day" to 10-minute intervals. Data, based upon present standard sampling rates, may well be misleading, as we can prove dendrite development can occur within only 20 minutes. Add our use of current limiting resistors in the test circuit and we can now preserve dendrite growth for subsequent failure analysis. This is a far more thorough test than any other supplier presently performs, so that we can be confident of our claim of material Synergie™.

Further details from Graham Naisbitt, Managing Director, Concoat Ltd. Tel: +44 (0) 1276 691100; Email: graham.naisbitt@concoat.co.uk