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BGA rework

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#48479

BGA rework | 19 March, 2007

Hello - what's coming up as the top reason for BGA rework? Are there more handeling issues than actual problems with SMT placement / rework?

Sorry it's a really general question, but i'm after some really general answers. :)

Chrissie

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CL

#48500

BGA rework | 20 March, 2007

Hi Chrissie,

BGA Rework from one CM's view:

10% process problem (printing, reflow, voids, etc) 10% component failure (no other problem found) 80% "The board does not work therefore it must be the BGA"

This, of course, is exaggerated. My point being is that we have a number of BGA rework requests where there is no clear indication that the BGA is the problem. Because we are unable to see the connections, there must be a "cold" solder joint. The assembly usually does not work even after replacement.

My $.02

Chris

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#48503

BGA rework | 20 March, 2007

I agree with CL. Most people blame the BGA cause it's a mystery chip to most people. Only after replacing the BGA several times do most people look else where. 90% of the time it's something else.

Doing all your engineering work up front is the key. Make sure you are inspecting paste on pads after printing, verify proper placement. Make sure no one plays hockey with the BGA bfore reflow. Performing good reflow profiles is a must.

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#48741

BGA rework | 29 March, 2007

Humm OK - sort of what i thought - So 90% of the time it's something else - but I assume that if you say that you are fairly confindent that you have a robus process around BGAs - where as i do not.

Can we assume that it is actually the BGAs (as some of the faults do seem to go away when reworked and there is a general history of the board actually working with that design).

If we assume it is the BGA - what then are reasons?

Chrissie

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JD

#48777

BGA rework | 30 March, 2007

I agree completly. When the techs in the factory bring boards to me for the PCB operators to replace BGAs on I ask lots of questions before releasing it to PCB dept. Many times its a guess on the techs part because they are frusterated with troubleshooting. Be careful....

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#48781

BGA rework | 30 March, 2007

Hi Chris,

A lot of it has to do with your product, t-shooting devices and techs ability. There are ways to determine BGA are at fault. X-Ray is a good way to check for shorts. Insufficients are harder to find. Some people use a dye. They squirt it under the BGA, let it dry and then remove the BGA. Dye on a pad means there was no solder joint present when the dye was added.

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GS

#48786

BGA rework | 30 March, 2007

also.....

...Internal Delaminations, due to a bad handling of Moisture Sensitive Device (most of BGAs are Moisture Sensitive, =/> MSL 3)

By SAM (Scanning Acoustic Microscope) before to remove them from PCB, you could identify if de-laminated or not and the degree of delamination.

Best Regards...GS

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