I would first want to know if my "standard Tg" material rating is being effected after
relamination. If you are running DSC or TMA testing, on a reasonably scheduled basis, you
know pretty well your product's true Tg. After this, I would be concerned about how much heat
your board is seeing relative to the device operating temperature.

When running the above tests, you may view results graphically. This allows you to clearly
see when and where in the cycle the laminate expands and goes "liquid", at what rate, and
when it begins to destruct.

If your board material, and that of your product, is 125 degrees Tg and it is seeing that
temperature, or very close to it, for continuous periods, you certainly may be concerned. It
is unlikely, unless you run thermal analysis, your product is suffering with this particular
combination of component heat and material Tg. However, if cost is of little consequence, it
would not hurt to stay outside the range of high operating temperatures (by at least 10
degrees) by using a higher Tg laminate, core, and prepreg material combination.

Earl Moon

################################################################
TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
To subscribe:   SUBSCRIBE TechNet <your full name>
To unsubscribe:   SIGNOFF TechNet 
################################################################
Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312
################################################################