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Tantalum influence on other components

Views: 1557

Vladimir

#46732

Tantalum influence on other components | 17 January, 2007

Hi, I am process engineer of SMT production. We have some strange problemn with tantalum capacitors. 1 case: If tantalum capacitor placed near BGA and one of his legs is connected to one of the BGA balls, after reflow we can see short between two or three balls that near the ball, that connected to our tantalum capacitor. The short happens in ~90-95% cases in specific board.After removing tantalum capacitor from SMT line (now we are assembling it manually) we have 0% fails. 2 case: Some small resistors or capasitors that placed correctly, but near the tantalum capacitor, after reflow have billboarding problem or disappeared from they places. I think that this is or magnetism or electrical charge problem. Maybe somebody has the solution or can explain me the reason of this problem.

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Phil J

#46733

Tantalum influence on other components | 17 January, 2007

The most likely cause is moisture vapor outgassing violently from the Tant package. They are known to be moisture sensitive. Try baking some at 120C overnight and reflowing those.

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#46734

Tantalum influence on other components | 17 January, 2007

Maybe, but distance between Tantalum capacitor and BGA is about 1cm. Also how evaporation can affect on the BGA balls and can be cause of short?

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#46738

Tantalum influence on other components | 17 January, 2007

Vladimir,

Phil J is right. Tantalum�s moisture vapor outgassing is the root of the problem you are searching for. Internal pressure of entrapped moisture becomes very high in reflow zone. Vapor jet shifts your components and affects BGA�s bumps. Baking and proper handling/storage is only one possible solution of this issue.

BR, Pavel

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Vladimir

#46739

Tantalum influence on other components | 17 January, 2007

Thanks - I will try ASAP.

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#55951

Tantalum influence on other components | 12 August, 2008

hai, in our smt process we are facing the following problem. The Case A tantalum capacitor used in our PCB assembly - during reflow process get shifted, due to which other components nearby that also found missing. what are the causes for this problem

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