Hi all

We are looking at the process, however I'm starting to think it’s a combination of two : 1 ) the warpage of the substrate during reflow along with 2 )barely adequate gold/nickel on the pad
It would explain why its just corner areas are suffering the adhesion, as its holding on by the skin of its teeth, and then we bend it!

We've done a trial over the weekend buy building side 1 an then using re-fluxing on side 2 BGA pads during the first IR pass, its seems to clean the pads enough to get a good bond.

Regards
Paul




Paul Taylor
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-----Original Message-----
From: GRIVON Arnaud [mailto:[log in to unmask]]
Sent: 23 June 2014 10:40
To: TechNet E-Mail Forum; TAYLOR Paul R
Subject: RE: [TN] Soldering Issues on Freescale PGA357

Hello,

As mentioned by others, your Freescale MPC860DTCZQ50D4 component uses a pretty conventional 1.27mm-pitch PBGA357 package of 25x25mm² size.
Changes of the BGA PCB substrate material or molding compound can have an effect on the BGA warpage behavior during reflow, but I am not sure this is the explanation in your case.
I have seen similar problems when the die size is very small compared to the package size, so it may be worth to check this (should be visible by X-Ray).
Also, moisture absorption is known to have an incidence on BGA warpage and could be investigated.
What is the stencil thickness used? Things will go worse if the stencil thickness is reduced because of the other BGA/components on your board.
Keep us posted.
Best regards,

Arnaud Grivon
PCB/PCBA Technology Expert
Corporate Engineering/TGS
18, avenue du Maréchal Juin
Bât. C - Bureau C2-135
92366 Meudon-la-Forêt Cedex
France
Tél : (+33) (0)1 70 28 23 88

-----Message d'origine-----
De : TechNet [mailto:[log in to unmask]] De la part de Paul Taylor Envoyé : lundi 16 juin 2014 17:53 À : [log in to unmask] Objet : [TN] Soldering Issues on Freescale PGA357

Hi

new to the forum, although in a previous life I used it quite a lot!

We use the Freescale MPC860DTCZQ50D4 in one of our designs, we've had a few issues with soldering at our sub-contractor which has got worse as we just don't seem to be able to lock down the root cause.
We have other BGA's on the boards (different pitches) which solder ok

The problem is always the outer pins in the corners , I've a lot of infor on the tests we have done, but I had seem a post about contamination of the balls on the Motorola package, which to be frank I hadn't considered

I've also seen some info about substrate changes which I'm wondering if it also was connected

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