Hello as you know I recommend glass rather than ceramic as you can see
through the slides and use them for testing all types of BGAs as well
for ball wetting.

If you would like the parts tested I am happy to do it for you and
provide you the results back. This is part of a NPL project we are
running on solderability testing so we can examine know soldering
problems which increase defect levels. The offer is there if people are
facing defects in manufacture relating to solderability.

To expand on the project I am currently working with the NPL Team on the
real impact of solderability on process yields. As you know many people
say they have a solderability problem, but the term is used incorrectly
and it’s often related to other process or design issues.

I would like to know if you have any specific components or component
types that regularly fail to wet correctly so we can test some sample
parts from production line as they occur over the next couple of months.
The solderability of surface mount or conventional parts is part of the
project and not PCBs.

The aim is to help us develop new solderability test methods and
criteria to more accurately predict process yield. It is import to
determine that the process problems are related to solderability, but
this can be determined through further discussion. We will need some
process data and component data on parts for testing.
 

Bob Willis
2 Fourth Ave, Chelmsford,
Essex, CM1 4HA, England
Tel: 01245 351502
Fax: 01245 496123
Mobile: 07860 775858
Email: [log in to unmask]
Web: www.leadfreesoldering.com
Web: www.bobwillis.co.uk
 

-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Gabriela Bogdan
Sent: 10 September 2004 17:24
To: [log in to unmask]
Subject: [LF] Tin plating on leads HELP!!!

Dear friends,
After assembly, on all circuits there was one fine pitch PLCC from a
certain vendor which had lots of small solder balls between the leads,
even on the solder mask dam between them.
Other PLCC's with the same pitch were clean.
We tried to see the amount of solder balls by X-ray, and found many more
behind the leads.
At first we thought that our solder paste was the culprit, but seeing
that other components were "normal" , we looked closer to the leads by
X-ray, and saw a lot of small voids only along the leads of the bad
component, these voids reaching to the upper end of the leads, where the
solder paste did  not reach. Visually, the upper part of the leads was
very rough.
I suppose that the tin plating of the leads contained additives which
epand during soldering, even burst out, and "spit" the molten solder all
around.
If this is the case,how could I reject such components during incoming
inspection?
Should I do a solderability test for each batch on a printed ceramic
plate?
Gaby

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the BODY (NOT the subject field): SIGNOFF Leadfree
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