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September 1999

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Subject:
From:
"Hollandsworth, Ron" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Mon, 20 Sep 1999 11:23:49 -0500
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Steve:
Excellent question, and the timing is perfect.

1.  What is the finest pitch that can be used with the HASL process?????

2.  Does the HASL process still produce the doming affect on traces and
pads???
        Question:  If the HASL process, now days, can produce a relatively
flat surface, then, with solder paste screened onto the CCA the parts should
stay in         place.  "In place", meaning not skewing from one direction
or the other.

3.  If fiducials are a problem for vision equipment, the what steps can be
taken to keep fiducials level for the vision equipment?????

4.  Next question is concerning mounting holes and ground planes.  Will HASL
leveling give as good a ground plane as Ni/Au??????

5.  What about BGA technology????   Does this question roll up into question
number one????

The reason for my questions is because of the Ni/Au contamination issues.  I
thought that the problem was more prevalent with boards associated with only
wavesoldering, however, I have learned today that SMT is not immuned.  I
have had many of one type of board that has been assembled through our
process without incident.  Then, all of a sudden, we have the contamination
issue.  When checking our process, we see no process change.  It comes, it
goes, and in the mean time it is very expensive when circuit card
assemblies, not bare boards, have to be scrapped.

Ron Hollandsworth

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