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Poor soldering on Motorola 357 PBGA



Poor soldering on Motorola 357 PBGA | 27 October, 2000

We are having problems soldering this motorola part(XPC860TZP50B5). After reflow, some of the balls appear to be sitting on the reflowed paste rather than wetted to it. We reviewed parts and found oxidation on many. We have four other BGA's, from other manufacturers, on the board which solder very well. The profile has been reviewed by the paste manufacturer and they said it is fine. We have talked to a CM with the same problem on the same package. Motorola has told them that the parts are acceptable. Does anyone have experience cleaning oxidized BGA's? Does anyone know a spec for BGA ball cleanliness? I would like to discuss solutions with anyone who has experienced this problem on this part.

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Glenn Robertson


Re: Poor soldering on Motorola 357 PBGA | 27 October, 2000

Chris -

You are not the first to see this problem. I have seen a similar case on parts from another company. There may be a way to "clean" the parts but I'm not aware of it. Maybe someone else will have an idea. I suggest you ask Motorola how they can be confident that the parts are good in light of the evidence that you have to the contrary. They should be willing to provide some type of data on the composition and surface condition of the solder balls, e.g., Auger analysis, etc. Good luck.

Glenn Robertson

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Dason C


Re: Poor soldering on Motorola 357 PBGA | 2 November, 2000

Chris, can we share some more information? I am running Motorola 357 BGA with PN XPC860MHZP50C and the problem for me is a large amount of void (checked by 5DX). I checked the ball surface and found some sketch on every single ball (it may caused by testing the device). I am not sure that the sketch can caused the contamination and create the void problem. I will send some BGA for reballing and found out the result.

Rgds. Dason

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Glen Mantych


Re: Poor soldering on Motorola 357 PBGA | 6 November, 2000

Glenn, we have been fighting perhaps the identical problem for nearly a year on a 1mm pitch BGA, we have performed numerous laboratory analyses of defective joints and virgin parts in an effort to specifically identify the cause of the no-wet joints. We have a reasonable amount of data, an understanding of the metallurgical/surface condition, an understanding of the process variables that contribute to the condition, but no complete solution. Do you want to exchange info. Glen

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