I'm outside the world of round robin testing - most of the time. Therefore,
I do have a question.

Going back many years, we in the MLB business had ILS problems but didn't
call it that. We knew, that when using very resin rich materials, certain
forces were exerted diagonally to the trace/pad to conductor interface
casuing cracking or separation. Most of what I talk about today is imposing
requirements using more moderate glass styles and corresponding resin
contents. I do this in all my designs at all the places I work. Again, my
Table II talks to this and points clearly to 2113 and 2116 glass styles with
very well balanced resin contents as percentages resin to glass ratios.

I talked about my Asian experiences and their total lack of using, or even
knowing about, 2113/2313 glass styles. This has interested and somewhat
surprised me for a couple of years but not as surprising as recent
discoveries netotiating with emerging (new generation I call them) board
shops. The teleconferences and emails have yielded some progress.

I just received compliance in two MLB constructionw wherein the shops in
question now are willing to work, even though without 2113, with highly
resin rich types (1080 as one example) "surrounding" very resin poor
materials (7628 as one example with the other being 1506) to achieve the
same overall board thickness and individual dielectric thickness to achieve
all physical and electrical objectives. I consider this a breakthrough even
though I and several board shops in this country have been doing this for
years but with an advangage of having 2113 materials to work with.

Also, using these materials in combination, according to my Table II and
other requirements in my book, we have maximized dimensional stability in
all axes including those forces in the diagonal. Therefore, we have
minimized ILS according to the thousands of x-sections I have - before and
after thermal stress. I certainly would like to know how these designs and
boards would hold up under the electrical stress testing so far discussed.

Earl

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