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  for Metal Finishing since 1989
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Solder Bridging

2005

Hi I'm a Plating process Engr working in one of the semiconductor company My problem is about the metal contamination issue on the Pure tin plated parts
which lead to solder bridging. Problem only happens on Pure tin Process specially
on the fine fitch product and it is visible after plating process. Is the pure tin Chemical / process is susceptible to metal contamination. Are there any theoretical explanation why this things happen .What is the best solution. Thanks

Gregorio Bronosa Jr
Semiconductor - Singapore

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Could be that the tin isn't wetting properly and this cases the bridging, or it could be that the solder you're using isn't the right one. If the tin doesn't wet, use a different flux. There has been a move away from lead-tin solder as lead is now an industrial no-no in the west. One of its benefits was it reduced or almost eliminated the whiskering in solders. There are other metals that will help with tin solder, so look for copper and bismuth or silver as an additive in the solder

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
2005

Can you tell us some more details about the history of your part. How much time lays between the plating and the soldering? Is ist bright tin or matte? How many µm of Tin are on the part an is there a barrier layer (like Ni or Cu)? What is the base material?

Oliver Brenscheidt
Otto Brenscheidt GmbH & Co. KG - Sundern, Germany
2006

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2006

Hi,

Growth along the package body is due to the conductive material in between the leads. It might have come from the mold releasing compounds present in the mold cleaning compound. Check whether the affected device is molded just after the cleaning of the molds. An improved Electrolytic deflashing will remove this type of conductive ions. You can do EDX on the affected area and find out the type of ions present.

Regards,

Prince C
- Chennai, Tamil Nadu, India

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Hi, I tend to agree that the contibution factor is due to the conductive ions of the mold releasing agents.

Ex-plating process engineer, Singapore

Emily Yew
- Singapore
2006

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I think the problem mention is more on bath impurity or suspended particles which requires good plating bath maintenance.

Check your filtration system, bath cleaning procedure, belt activation procedure.

Beatriz C Amio
- Singapore
2006