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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