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BGA short at same spot after few time rework.

zam_bri

#6086

BGA short at same spot after few time rework. | 25 April, 2001

Hi,

Can anyone advise what would be the possible cause of having the same short problem at the same spot even after 3 time rework, with a brandnew BGA.

I have rework boards with BGA shorts. The problem is most of the shorts boards, will passed after first time changed the component, but they are a few boards will have the same short at the same spot, even after three or four time change. What a mystery for me !!!

Can someone, tell me what would be the possible cause ? Thanx in advance.

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#6089

BGA short at same spot after few time rework. | 25 April, 2001

Zam_bri: If it were a mystery .... there can�t be any answers .

Possible causes:

- Short is in the PCB ( not very propable, cause you�ve checked that ) - Short is in the BGA ( not very propable, cause you�ve checked that ) - Short occurs due to solderbridging between two neighboring balls

Well, that raises different questions:

Does the PCB or BGA warp during rework? Is the surface ( soldermask) OK prior to the attachment of the new BGA? How do you apply Paste or what does your process look like? Is this occurring only with one product or with all kind of Boards, BGAs ?

Hard to tell from the distance you should provide some more details.

Wolfgang

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#6095

BGA short at same spot after few time rework. | 25 April, 2001

You can make bare BGA balls short together, depending on how you choose to heat the device. Lookit ..

[http://davesmt.50megs.com/pictures/ select bgashortng.avi]

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spchua

#6104

BGA short at same spot after few time rework. | 25 April, 2001

Hi,

Guy, please check the lamination of the PCB's; or the the BGA rework machine, some things like m/c levelling, and force placement head

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#6107

BGA short at same spot after few time rework. | 26 April, 2001

Dave,

nice movie !! Seems you�re expanding your already great services.

It would be interesting what conditions lead to this phenomenon. To me it seems that one ball is blown up by voids extremely.

Can you tell more about it ?

Hope to see you at Jimbo�s sometime

Wolfgang

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#6118

BGA short at same spot after few time rework. | 26 April, 2001

Hey Wolfgang:

I was down at Jimbo's and tried a McEwan's Pale Ale, yech!!! And Scotch beer [eg, McEwan's Scotch Ale, Tennant's] has been so berry, berry good to me, helping to sauve the travails of winter, until I could starting working on wheat beers again. I'd enjoy an adult beverage with you too.

Bob Willis gave me that vid. So, he would do a much better job than I in describing the particulars. But as I recall, voiding was were I leaped also. Again fuzzily, I think the majority of the unusual distortions of that one ball were brought on by solder flowing along traces that were between the NSMD pad and the solder mask.

But the main purpose of the vid and my posting it to yall is show that all the balls balloon in size when run through a fast temperature ramp.

Sorry I wasn't more help Dave

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Carlos A. Gutierrez

#6153

BGA short at same spot after few time rework. | 2 May, 2001

I�m looking for information about who has a service for reworks or reattachments PBGA chips in Mexico

How can i found it?

Thanks a lot

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