Bob, George,Paul!
Thank you.
Bob, Sunday I will see if I can get a new component.
Gaby
----- Original Message -----
From: "Bob willis" <[log in to unmask]>
To: "'(Leadfree Electronics Assembly Forum)'" <[log in to unmask]>; "'Gabriela
Bogdan'" <[log in to unmask]>
Sent: Friday, September 10, 2004 7:04 PM
Subject: RE: [LF] Tin plating on leads HELP!!!


> 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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