Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


BGA ball seperation

Views: 2736

whippingpost

#38189

BGA ball Separation | 2 December, 2005

I have an assembly that uses several different BGA packages. During troubleshooting we have found that some of the balls in the corners of the BGA's are separated from the underside of the package. The PWA is approx 10�x10� and the components vary from �� from the edge to 1.5� from the edges. They have been installed into the end item then removed several times for updates. Right now I am leaning in the direction that these failures are being caused by the flexing of the PWA during the installation/removal from the end item. Has anyone else seen this? I am thinking that maybe we need to design stiffeners onto the PWA? How about under fill, would that help?

This message was posted Add this forum to your site! Click to learn more. the Electronics Forum @

reply »

whipping post

#38214

BGA ball Separation | 5 December, 2005

no one else has seen this?

This message was posted Add this forum to your site! Click to learn more. the Electronics Forum @

reply »


RDR

#38215

BGA ball Separation | 5 December, 2005

I'm sure that we have all seen it but it can be from so many different things. Definitely can be from flexing, Are you 100% sure that they are good prior to this install remove process?

reply »

whippingpost

#38217

BGA ball Separation | 5 December, 2005

Not all but some were tested O.K before the failure. What are some of the other reasons for ball separation from the component body besides mechanical stress?

This message was posted Add this forum to your site! Click to learn more. the Electronics Forum @

reply »

#38222

BGA ball Separation | 5 December, 2005

thermal cycling chemical reactions (can occur slowly) they were only touching before and not really a solid solder joint

reply »

Billy D

#38223

BGA ball Separation | 5 December, 2005

Dude, make sure you're not getting too hot, too quick. If the BGA "dogears" in the oven, or during a rework procedure, it'll either short, or get very strained, depending on which way the part moves, up or down. Also, bake the hell out of them, as if there's ANY moisture in there at all you will have serious problems. Try to keep the case temps under 220C at all times! (Profile the hell out of this board if you need to) A joint temp of 213-ish will (should) keep you under 220C on the case.

reply »


RDR

#38228

BGA ball Separation | 5 December, 2005

Ina ddition to the above it can be from CTE mismatch and the joints are breaking during cooling. Is this an Altera part?

reply »

DC

#42934

BGA ball Separation | 25 July, 2006

Russ, we had similiar issue on the corner seperation. The board is ENIG and the part is Altera FBGA 1020 (Super BGA) and reflowed by tin/lead paste. Please comment your concern on Altera parts! Is CTE mismatch?

reply »


RDR

#42936

BGA ball Separation | 25 July, 2006

All my studies led me to believe that it was CTE mismatch of this package. Altera was of less than 0 help in this matter. The other possibility was an ICT test fixture. Unfortunately (?) the design life of this product was at end and the new design utilized diff manufacturer with basically same design. New MFG has had 0 failures to date after 1000 or so installs.

So I would not say it was definitive that it was the package and CTE issue, but I believe it it was. It was also the super BGA package not quite as large as yours though.

Good Luck

Russ

reply »

PCB Soldering Tools

HeatShield Gel- thermal PCB shield during reflow