Mr. Ingemar,

This is not to fix corners during wave soldering.  We are interested in
decreasing the amount of field failures which are occurring because of the
mechanical stresses the BGAs undergo.

According to Mr. Stadem's email, he had quite an increase in cycles to
failure when he added chipbonder to the 4 corners of his BGAs.

Thank you for your input. 
 
David


-----Mensaje original-----
De: TechNet [mailto:[log in to unmask]] En nombre de Hernefjord Ingemar
Enviado el: Tuesday, April 17, 2007 1:51 AM
Para: [log in to unmask]
Asunto: Re: [TN] Tacking corners of BGAs

David,

Are you aiming at loctiting to fix corners during wave soldering? If you
have that kind of corner problem, you seem to have a coplanarity issue. To
fix that with a epoxy dot does not seem to be the best way. I would rather
go to the BGA manufacturer and ask for good packages. Another problem, that
occurs up and then, is bad corner ball wetting or even corner ball disrupts.
I doubt such anomalies can be treated by means of epoxy dots. Agree with
John Burke, we need know little more about your 'mechanical stress'.

Inge 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David Tremmel
Sent: den 16 april 2007 23:56
To: [log in to unmask]
Subject: [TN] Tacking corners of BGAs

Dear Technetters,

 

We have a quality issue where some of our boards are returning because the
BGAs need to be protected against mechanical stress.  We were considering
using Loctite´s Chipbonder 348 on the corner of the BGAs in question (we
would not to use an underfill).

 

Does anyone have any experience with Chipbonder 348 in this kind of
application?

 

Would anyone care to suggest a heat-cured adhesive for tacking down corners
of BGAs?

 

 

Thank you in advance,

 

David

[log in to unmask]


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