Dear Jim

This may be a very stupid idea, but what about using ultrasound?

I belive they use ultrasound to detect microscopic fractures in mechanical
assembly's and the joint between the CBGA and the solder ball is mechanical.

I dont know what the ultrasound would do to the chip or the wire bonds but
it may be worth some more enquiries to the component manf.

I would be very interested to read how you got on.


===== Original Message from TechNet@PAT [log in to unmask] (TechNet E-Mail
Forum.) at 28/09/98 13:50
>Hi, Technet:
>
>We've been experiencing approximately 5% failures on 228 ceramic BGAs for open
>circuits.  Evaluation of the suspected components revealed a ball attachment
>problem to the component solder pad.  We've seen anywhere from partial wetting
>up to total non-wetting of some of the component pads.  These devices are
>"dimpled" BGAs, where the pads are recessed approximately .006" below the
>bottom surface, so it is conceivable that the solder balls are just held in
>place, without any metallurgical bond to the component metallization.
>
>Can anyone offer any suggestions as to how we can inspect these components to
>detect the solder defect prior to assembly?  X-ray doesn't work, and I don't
>think laminar x-ray would either.  Are there any other inspection systems that
>could be used?
>
>Thanks in advance,
>
>Jim Marsico
>AIL Systems Inc.
>(516) 595-5879
>[log in to unmask]
>
>
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Mark Austin (Process Engineer)
ACW Technology Ltd
Hylton Road
Petersfield
GU32 3XX

TEL - (01730) 300000
FAX - (01730) 266045

DDI - (01730) 304401
MA @ ACW.CO.UK

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