Phil, all

You are on the right track with testing for blistering/delamination at LF
assembly as an indicator of a material's capability to withstand LF
processing. You should keep in mind however that: a material could pass
your test, but if you have that material fabb'ed by a different PCB
fabricator you could get a different result; AND, if you have the material
fabb'ed into a different board (more layers; thicker) you could get a
different result, AND if you have the same part fabb'ed by the same PCB
supplier fabb'ed again from a different lot of material - guess what? -
you could get a different result.

This is a huge problem. If a material can't pass muster initially, then it
isn't LF capable; but even if it does pass muster, we must still maintain
vigilance. It will likely  be awhile before these materials and the
methods to turn them into multilayers settle down into anything close to
the predictability we have had with the current batch of materials at the
old reflow temperatures ....

Valerie




Phil Nutting <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
12/13/2005 09:32 AM
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Re: [TN] Qualification of the Pb-free capable manufacturers






Charlie and Werner,

Our current solution is to fab a group of test boards all at the same
time, but using several different laminate materials from different
vendors.  We will then run them through a temperature torture test at
the same time.

Example; 3 Tg 170 board materials processed together, then run through
wave together.

We will be watching for blistering and delaminating.

Phil


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