Hi Al.
Cleaning:
If your cleaning process has been "qualified" to clean under BGA's, then
yes, you can do that. We have been successful (we think) at cleaning
under .7mm BGA's. Also, check the design of the board to make sure that
AO flux will not be trapped within a via. Of course, if you use NC, you
don't need to worry about cleaning :-)
Rework:
We have used both processes successfully, but, it depends. The joint
will look different which may mean the reliability is different. If the
sphere is Lead Free or "High Temp" you will need paste. Using a micro
stencil is more work, but I feel it provides for a more reliable joint.
If you do not have a micro stencil and you need to get the boards out,
then flux may be just fine :-)
-Carrie
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of
[log in to unmask]
Sent: Friday, October 08, 2004 8:50 AM
To: [log in to unmask]
Subject: [TN] Soldering .8mm BGAs
Hello Technetters:
Processing a 16"x20", .125" thick double-side mixed-tech (smt both
sides, and pth component side) with at least two .8mm BGAs with .45mm
balls:
one is a 84 pin package is a 9 x 15 - 135 - ball matrix with 51
depopulated balls in the center of the package the other is a 8 x 12 -
96 ball - matrix with 8 depopulated balls - 4 at either end of the
matrix
Two quick questions:
Can I clean (in-line) using di water only if I use OA flux? Or, do I
need to switch to no-clean for BGAs less than 1mm?
For rework, flux only? Or can I micro-stencil or dispense?
As always, thanks in advance for your replies,
Al Kreplick
Sr. Mfg. Eng.
Teradyne, Inc.
500 Riverpark Drive
Mail Stop NR500 1-1
North Reading, MA 01864
Tel: 978-370-1726
Pager: 888-561-6485
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