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April 2008

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Subject:
From:
"Igoshev, Vladimir" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Igoshev, Vladimir
Date:
Fri, 11 Apr 2008 09:52:12 -0400
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Hi Steve,



In order to start getting right answers, you should probably figure out first where the shorts happen: on the flex or BGA side, as well as to establish what material (the composition-wise) is causing the shorts.



Regards,



Vladimir



----- Original Message -----

From: TechNet <[log in to unmask]>

To: [log in to unmask] <[log in to unmask]>

Sent: Fri Apr 11 09:42:31 2008

Subject: [TN] Possible flux contamination issue



Good Morning,



We are assembling a BGA connector onto a flex circuit. The BGA has leaded

balls and the BGA manufacturer uses a no-clean process to attach the balls

to the connector and does not clean afterwards. 



When we assemble the BGA connector to the flex we use water soluble paste

and then we clean. After damp heat cycling we have seen some shorts. When we

take off the connector we see flux residues on the underside of the

connector but not on the flex.  So my question is - what are the concerns

about mixing no-clean and water soluble? Is the failure likely due to

inadequate cleaning or is there something else I should be concerned about.

I realize this is probably not the way it should be done but some days you

just do what the customer wants - good or bad. Thanks in advance. Steve

Kelly



 



Steve Kelly



(416) 750-8433 (work)



(416) 750-0016 (fax)



(416) 577-8433 (cell)



 





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