Dave Hillman asked: > Hi Jerry - > > With the decline of ceramic components and the increase of plastic > components with this be an issue again or because of past lessons > learned be a non-issue? For conventional plastic packages, it is likely a non-issue as it can be solved in various easy ways (coatings, metallization, polysilicon passivation...). For chip scale packages, it could be a concern where lead bearing solders are in intimate contact with MOS dice. I can imagine various types of solder bumping approaches that might increase the exposure. It is also a concern (and I use that term advisedly) for _any_ material containing alpha emitters which would be in intimate contact with a memory cell on a die. The die coat materials used in RAM (at least those in use about 10 years ago) were pure polymers known to be free of these emitters. The environment has lots of these nasties like radon gas and other decay products. In the day of the 16K RAM, there were nearly no precautions taken to deal with alpha emitters, and it was the type of problem which took sensitive and thorough lab/theoretical analysis to measure. There were experiments conducted deep in salt mines, as I recall. My comments are based on old information. That said; my opinion is that for those of us who make boards, it is no concern. For those involved in chip scale packaging, review the literature and talk to a physical chemist or two. regards, Jerry Cupples Interphase Corporation Dallas, TX USA http://www.iphase.com *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To subscribe/unsubscribe send a message <to: [log in to unmask]> * * with <subject: subscribe/unsubscribe> and no text in the body. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ***************************************************************************