Hi Andy,

We have been building blind via boards for about 12 years using the
sequential lamination process.  Each half is built separately and then
bonded together for a final board.  About 50% of our work is blind via with
4-10 layers.

We have come up with a new process over the last 4 years called PhotoLink.
This process is similar to IBM's SLC process which is used in all of their
ThinkPad laptop computers.  It is a photoimageable dielectric, similar to
soldermask.  We use this instead of laminate for the outside layers.  With
this process we can photographically put in blind via holes down to 1 mil
instead of drilling them.  Currently we advertise 4 mil blind holes in a 10
mil pad. This method of making blind via boards is state of the art.  We
expect PhotoLink to be a growing percentage of our total business in 1997.
Typically, a PhotoLink design would be 30% less expensive than a standard
sequential laminated blind via board with an increased density of about 40%
because of the smaller pads.  We will be having another seminar soon
concerning this subject in Chicago. We recently listed the last one held in
Boston over TechNet. By the way, Motorola has chosen this process as their
favored process.  Intel just purchased Tessera's MicroBGA process and will
be publishing our name as a company with the technology to build boards that
are compatible.    

We have been building sequential laminated for two major telecommunication
OEMs as well as industrial and medical applications.  I mention this because
it should give you a comfortable feeling that it is a standard technology.

If you have any further questions about this technology or if you would like
a formal DFM presentation, I would be happy to talk with you about it.

I hope I have been of some help, if you have any questions, feel free to call.







Sincerely,


Sid Tryzbiak
VP Engineering
Continental Circuits, Inc.
Winter Springs, FLORIDA 32708    
407-699-5000

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At 08:26 AM 12/9/96 -0400, you wrote:
>
>
>
>
>  My company is looking to design a multilayer PCB with blind vias. Another
>  company will do the actual fab. I've heard there's more than one way to
>  do blind vias: either controlled depth drilling or fabbing and drilling
>  two halves of a board separately and sticking them together. Does anyone
>  have any experience with either of these methods, and is there another
>  way I don't know of? Which way is better, what are the risks, etc? Any
>  info would be appreciated. Thanks,
>  Andy Buonviri
>  Ixthos, Inc.
>  [log in to unmask]
>
>
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