Subject: | |
From: | |
Date: | Wed, 2 Apr 97 16:00:00 -0800 |
Content-Type: | text/plain |
Parts/Attachments: |
|
|
Item Subject: Assembly - via hole plugging and solderballs
What you are seeing is the outgassing of the flux through the wave
soldering process. This is a very common problem and the best method
is to not mix mixed technology boards with plugged vias. I have never
heard of any solution to this when wave soldering is involved.
______________________________ Reply Separator _________________________________
Subject: Assembly - via hole plugging and solderballs
Author: Non-HP-Marti.tully ([log in to unmask]) at
HP-Vancouver,shargw2
Date: 4/2/97 2:29 PM
Several of our PWB suppliers have used a via hole plugging process with the
following sequence: LPI, HASL, partially plug via hole (component side).
With mixed technology boards, our assemblers (in house, contracted etc.)
all experience a phenomenon where the solder erupts from the top of the via
during the wave process. The eruption looks like a volcano and varies in
severity. This eruption results in several problems including solderballs.
Most of the plugged vias lie under components and the spacing between vias
can be equal to or <8mils. Many components sit very close to the board's
surface.
This seems the PWB industry preferred method to plug holes when LPI is
used. How do assemblers prevent the eruption of the solder through the
top of the plugged via during wave? Is this a common problem in assembly
or rare?
***************************************************************************
* TechNet mail list is provided as a service by IPC using SmartList v3.05 *
***************************************************************************
* To subscribe/unsubscribe send a message <to: [log in to unmask]> *
* with <subject: subscribe/unsubscribe> and no text in the body. *
***************************************************************************
* If you are having a problem with the IPC TechNet forum please contact *
* Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] *
***************************************************************************
***************************************************************************
* TechNet mail list is provided as a service by IPC using SmartList v3.05 *
***************************************************************************
* To subscribe/unsubscribe send a message <to: [log in to unmask]> *
* with <subject: subscribe/unsubscribe> and no text in the body. *
***************************************************************************
* If you are having a problem with the IPC TechNet forum please contact *
* Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] *
***************************************************************************
|
|
|