I appreciate the comments from Glenn Heath (Merix), I think it definitely
worth more than just 2 pennies. :)
The experience that Glenn shared proved what I'd mentioned in my message:
different manufacturers, having different setup, equipment, may come to
different conclusions about the economics of processes. However, the
important conclusion from our discussion is: "We both agree that microvia
(blind via) can be a cost saving solution to achieve higher density."
If I'm not mistaken, I believe the design rules for the microvia are pretty
much the same for either plasma or laser drilling (.005"-.006" diameter,
.012"-.016" pad). I think it would be nice if we can all agree upon a set
of design rules such that the boards can be made by either technologies.
That way we can get rid of the 2nd source suppliers issue, which is a big
concern from the designers especially on new technologies. Any speculation
about which technology is going to take over the market is meaningless
unless there is a market.
Mason Hu
Zycon Corporation
______________________________ Reply Separator _________________________________
Subject: RE: Plugged Vias (and laser vias and plasma vias)
Author: [log in to unmask] at corp
Date: 10/17/96 8:11 PM
Both Mason Hu and John Gulley make valid points about via in pad
techniques, but I thought I should throw in Merix's 2 cents on the
matter as well.
Mason is right in his statement that laser vias are not always
slower and more expensive than other methods. He is definitely
right in his statement that the use of microvias can make the
part less expensive than conventional (drill vias) boards through
layer reduction. I would add that microvias often make boards less
expensive through size reduction through the increased density which
is made possible by putting vias in pads.
A critical cost factor in comparing the various microvia methods is
the number of vias in pads. If the number is low, laser may be the
most economical and fastest method (unless it is not done in-house;
then shipping takes time). Because processes such as DYCOstrate (TM)
[plasma defined vias -- the process that John mentioned that Merix is
using] are batch processes, boards with a significant number of
microvias are less expensive than laser defined via boards. Merix
defines it as "buy one via, get the rest free". Because plasma etchers
are more common at board fabricators than lasers, the plasma defined via
process has a greater chance of being performed in-house and is therefore
often quicker regardless of the number of holes.
Mason's statement about Japan using SLC (IBM-Japan's process) and laser
is valid, but not surprising considering the plasma defined via process
was developed in Switzerland. In Europe, the plasma defined via process
is more popular. This is similar to the trends of immersion gold acceptance
in Europe versus OSP acceptance in Japan. I would say that comparing
the pricing of laser via boards to plasma via boards has not been very
thoroughly investigated. Mason may have been comparing Zycon's pricing to
HP-Germany's pricing and if that is the case you would have to factor in
duty, shipping, and exchange rates as well as board fabrication cost. For
the designs that Merix has seen, the DYCOstrate (TM) process has been the most
economical method of producing microvias.
As a whole, microvia technology has advanced very rapidly over the last
few years and is worth investigating by anyone who is interested in reducing
size, weight, and cost. Its use should not be limited to the issue of
plugged vias.
Glenn Heath
Merix Corporation
503-359-2652
[log in to unmask]
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