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Proper Handling of Immersion PCB Surface Finishes

Chris Perry - Printed Circuit Board Supply Chain Manager
Written by Chris Perry - Printed Circuit Board Supply Chain Manager
Posted on March 21, 2013 at 10:35 AM

Printed circuit boards (PCBs) with immersion finishes such as electroless nickel immersion gold (ENIG), immersion tin, silver, and OSP are appealing because they are lead-free. However, when handled improperly, these materials are susceptible to oxidation and corrosion from exposure to moisture and humidity. This oxidation causes dewetting after soldering, which can lead to poor joints at assembly and ultimately lead to failure of the board.

Solutions For Handling PCB Surface Finishes 

Careful handling will minimize oxidation and associated problems. Even natural oils from human skin can tarnish these finishes, so gloves are always recommended when handling printed circuit boards with immersion surface finishes. Additionally, storing your circuit boards in airtight packaging helps prevent oxidation due to humidity and moisture.

Examples:

PCBs with ENIG finishes that have been heavily oxidized due to exposure to moisture:

PCB with ENIG surface finish that has been heavily oxidized

Results of solder testing and the dewetting caused by the oxidation on the ENIG surface mount pads:

Results of solder testing and the dewetting on PCB

Topics: Printed Circuit Boards, Quality Solutions


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