Freezing an IC will modify its physical dimension but also will change its electrical property. From what you said I would guess that one of the timing of your design is very marginal and most probably too slow. When cooling some of the components the electronics actually goes faster and, the timing being then correct, your design start to behave correctly. Your engineer should review the timing of the design and can actually check on the board what happens to the signals when applying the freeze spray. But be carefull that probing on some signal will also change their timing... It may also well be that the timing problem is inside the PLD, to solve that one the engineer got to redo some simulation with min and max timing. Now freeze spray can also induce other circuitry to work. For example, an analog circuit could start working only when cooled down because it was too hot under normal ambient condition. Too hot because the design or assembly is incorrect and the component is actually used outside its maximum temperature rating... The best way to find which component is faulty, is to use a slim tube and spray directly on each component, making sure not to freeze the adjacent one. The component that will show the most effect on the fonctionnality is likely to be the one you should look at. Hope this helps, Jean-Luc Lehmann We recently received a prototype batch of 4 boards and experienced 4 for 4 failing test. Our techs sprayed down certain chips with Freeze Spray and the board began working properly, at least for a short period of time. I have checked prior tech net postings and have found fantastic responses as to why Freeze Spray can damage a the IC or board, but can anyone explain why they would begin functioning properly. Being a rookie component engineer I can fully understand the issues related to freeze spray, but out techs and design engineers are just going to point the finger since their units work when sprayed. To further complicate the matter the chips that are being sprayed are not all the same manufacturer and I can easily rule out a component failure. Our senior engineer thinks that it may be timing related since the main circuit being froze is the Altera PLD (20K400E) and related circuitry. Can anyone defend the use of Freeze Spray? Can anyone present a logical failure mechanism? /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\ The best Freeze Spray argument to date was Werner Engelmaier's: http://jefry.ipc.org/scripts/wa.exe?A2=ind9907&L=TechNet&D=0&m=23823&P=55370 However this points to failure after spray not the opposite. --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------