Just raw material, looking for gross incompatibility problems/major influence factors.
________________________________________
From: Phillip Bavaro [[log in to unmask]]
Sent: Wednesday, December 24, 2008 2:17 PM
To: TechNet E-Mail Forum; Thayer, Wayne; [log in to unmask]
Subject: Re: [TN] Underfill, inhibition due to leftover activators in the flux residue
Thanks Wayne.
I will do a little experimentation to see if I can recreate the problem in
a lab environment.
When you misted the sample, were you talking about an underfilled BGA or
just raw underfill material?
Phil
At 12:43 PM 12/23/2008 -0500, Thayer, Wayne wrote:
>I have been in underfill "hell" numerous times.
>
>I still don't have a complete understanding of what makes it decide to not
>cure properly, but moisture can be a big problem, as far as some of the
>Henkel products go. We are getting better results with extended bake
>cycles to eliminate any moisture from the assembly. This might have
>something to do with your problem too: Send it through the oven a number
>of times, and each time it will be a bit drier.
>
>I use mostly RMA flux and solvent clean. I have mixed raw RMA flux
>directly with the underfills we use and they seem to cure OK. Only way I
>could get the uncured goo witnessed sometimes on the production line was
>to literaly mist it with water prior to attempting to cure.
>
>Good Luck!
>
>Wayne Thayer
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Dwight Mattix
>Sent: Tuesday, December 23, 2008 11:46 AM
>To: [log in to unmask]
>Subject: Re: [TN] Underfill, inhibition due to leftover activators in the
>flux residue
>
>At 04:54 AM 12/23/2008, David D. Hillman wrote:
> >But - if you have a BGA that is sufficiently large and has significant
> >I/O, you are going to have some flux residue remaining under the
> >component.
>
>/heh no kidding.
>
>Phil,
>This under a 7xxx series MSM? Almost 700 pins on a .5mm or .4mm package?
>
>You're going to love the the 8xxx series. :-) lol!
>
>Merry Christmas,
>dw
>
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