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What are the possible causes why BGA would dislodge from the PCB

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LC

#49657

What are the possible causes why BGA would dislodge from the PCB | 1 May, 2007

Hi, We are encountering BGA problems where it dislodge from the board. Some are just by normal handling and some are results from drop test about 15 cm high.

We have checked our profile and they are in accordance to the BGA recommended reflow profile.

Other components in board on the same surface where BGA was mounted are showing signs of good wetting.

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#49673

What are the possible causes why BGA would dislodge from the PCB | 1 May, 2007

You say the BGA recommended profile? Or did you mean the solder paste recommended profile? I would use the solder paste profile over a parts recommended profile any day. You may need to create a hybrid of the two to get better results. What type of paste are you using? What finish is your board?

Once we know these things we can get closer to a solution.

In the mean I'll check with my scientist friend. He developed a fruit that will launch itself from a vehicle right before an accident.

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#49681

What are the possible causes why BGA would dislodge from the PCB | 1 May, 2007

Where are you measuring your temperature at? Are you measuring pad/ball interface temp through a hole in the board, or a lead on a different part, or board surface, or.....?

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LC

#50049

What are the possible causes why BGA would dislodge from the PCB | 2 May, 2007

In our first run, we actually followed the solder paste recommended profile then we were told to use the BGA recommended one. When we had the 2nd run we still got the same problem.

We're using Kester 909HPS (lead free) and ENIG boards.

Thanks.

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Bob R.

#50051

What are the possible causes why BGA would dislodge from the PCB | 2 May, 2007

Don't dink with the profile until you have evidence that the profile has something to do with the problem. Step 1 is a cross-section. Where are the joints breaking? Do the joints show signs of proper wetting & intermetallic formation?

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#50056

What are the possible causes why BGA would dislodge from the PCB | 2 May, 2007

I agree with Bob,

Do you have a long TAL, ENIG needs a longer TAL then other boards, on the side of this, Latest year there are a lot of bad Au plated boards, we had 3 batch of bad plated boards in the last year.

indeed maybe the problem isn't the profile. bart

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SWAG

#50061

What are the possible causes why BGA would dislodge from the PCB | 2 May, 2007

Restrictive carriers or lack of carrier in reflow can cause board warpage = bad for BGA's. Might be something to look at.

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#50078

What are the possible causes why BGA would dislodge from the PCB | 3 May, 2007

Hi LC,

Where are you getting your profile from? Are you actually attaching t-couples to the board? For BGAs the best place to measure is from the center of the device. This means drilling a hole in the board and placing the t-couple thru the hole against the BGA. It's prefered to place it against one of the balls and then back filling the hole with SMT adhesive.

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#50079

What are the possible causes why BGA would dislodge from the PCB | 3 May, 2007

Make sure you check to see that they are not lead-free balling and using leaded profile. We had this and had continous problems. We had to send out our BGA to get reballed.

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#50099

What are the possible causes why BGA would dislodge from the PCB | 4 May, 2007

Are you sure the BGA is not Leadfree and the proces you are using is a leaded process? If so then the Balls will not reflow and there will be cracking. Likewise the other way around

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#50104

What are the possible causes why BGA would dislodge from the PCB | 4 May, 2007

For the mixed alloy scenario, here's something from the fine SMTNet archives:

http://www.smtnet.com//forums/index.cfm?fuseaction=view_thread&CFApp=1&Thread_ID=10216&#Message40990

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#50109

What are the possible causes why BGA would dislodge from the PCB | 4 May, 2007

pillow defect?

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#50112

What are the possible causes why BGA would dislodge from the PCB | 5 May, 2007

Continuing with CF's point on mixed alloy processing of BGA, look here: http://www.aciusa.org/leadfree/LFS_SUMMIT-PDF/09_HILLMAN_Rockwell_Collins_BGA.pdf

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#50113

What are the possible causes why BGA would dislodge from the PCB | 5 May, 2007

We agree with Bob R

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