I agree strongly with Guy's approach below on this or any
other process opinion solicitation. I can guarantee you can
find people who have had very positive and very negative
experiences with ANY process used to make PWBs. The
approach I always council is that the process has to be
right for YOUR SHOP. So the first thing you need to do is
qualify and quantify you situational needs. If you can get
an excellent handle on what you will require from a process,
then it becomes easier to chose which process is right for
you.
Also, when someone gives you a good recommendation about a
process, find out what their situational needs were when
they bought into that particular process.
When someone has had a bad experience, find out their
situation as well if you can. It may very well not apply to
YOUR situation.
The suppliers of processes or equipment should be willing to
present proof sources for you to quiz. Take your time
talking to these people and find out what they really do
with the process or equipment and what they expect from the
process or equipment.
Well, that's enough. My soapbox is getting rickety.
Dave Sullivan
Rockwell Collins, Inc.
[log in to unmask]
______________________________ Reply Separator _________________________________
Subject: Re: FAB: Horizontal versus vertical etching
Author: [log in to unmask] at ccmgw1
Date: 1/29/97 5:27 PM
This is a very big question. You will receive a lot of pro's and
con's for each process. (I know I have my opinions) The best thing
you can do is decide what you are looking for in a finished etched
trace geometry. Process samples of different line widths and take
many cross sections. When you take your cross sections you will want
to cross section both top and bottom (horizontal) / left or right
(vertical) of the substrate as it was processed as well as traces that
are processed in parallel and perpendicular and at 45 degree angle to
the direction of travel of the substrate as it was processed. When
you read these cross sections you will be focused on what the sidewall
characteristic is of the left and right side of each trace and how
they relate to each other based on direction and position. With the
se cross sections you must also look at the position on the conveyor
top center bottom on vertical or left center right of a horizont
al unit. Once you gather this data you can then determine which pr
ocess will meet YOUR expectations. Include in this decision
controlled impedance and very fine lines if this is part of your goal.
When you measure the line widths make sure you compare the
measurement to the exact location on the A/W that was used to image
the test panel. Line widths on A/W vary and you want to remove this
variation from your comparison. Because each shop's expectations are
different each process finds it's own niche.
Guy Willingham
Zycon
[log in to unmask]
______________________________ Reply Separator _________________________________
Subject: FAB: Horizontal versus vertical etching
Author: [log in to unmask] at corp
Date: 1/29/97 3:16 AM
We would like to receive input on the positive and negative aspects
of horizontal etching with oscillating spray bars, versus vertical
etching of inner layers and outer layers using an alkaline etchant.
We would like to hear of experiences as to which method provides
the best results in terms of line width uniformity, top to bottom
consistency, and conveying of cores as thin as .004 with half ounce
copper on both sides.
Panel sizes vary from 12 X 12 to 21 X 30. Line and spaces down to
.004 X .004 for the smaller panels, .008 X .008 on the larger panels.
Please presume that equipment of either type is well maintained and
that the chemistry is under good control.
Many thanks,
Luis Rivera
CompuRoute, Inc.
Dallas, TX
[log in to unmask]
(214) 340-0543
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