In a message dated 8/27/99 6:26:31 PM Central Daylight Time,
[log in to unmask] writes:

> interesting , how thick is 52 ? (just curious) .
>  Earl we have the layers cost dilemma here :
>  What would be ratios of yields and costs from simple double sided FR4 ;
>  to 4 layers, 6, 8, >>> etc. ?
>
>  And why even's only ; no odd layers ever ?
>
>  thanks       paul

Hey Paul!

What you doing sending a email on your Saturday? Workin' a week-end or
something? I'm just answering you just to test what little I've learned about
PCB fabs ( I need to learn a lot more!) So all you teachers out there,
correct me if I'm wrong.

All layers start out as a double-sided copper-coated laminate, thus the even
number. The technology is advancing all the time (what's new?) but the
smallest core I've heard of is .014". So at that dimension, a 52-layer would
work out to .728" at the minimum...but there has to be some resin between the
layers, so I would think that it would be some VERY THICK BOARDS. (I've never
seen a 52-layer board! 18-layers is the most I've ever seen!)

The problem that I see with that many layers (and why Earl's boards are big
bucks!) is the registration between all these layers when making the fab! We
think we have problems putting some components on boards like this and
reflowing them, I'd hate to have the job of putting this FAB together!

 I've gone to the dogpile and looked around, found some stuff about resin
coated copper, but it was listed as a "product in development" so maybe you
might see some odd numbered layers soon...boy, I'm I dumb about this stuff!

-Steve Gregory-

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