Protektive Pak - Questions And Answers

I work on computers for our network. We have been reading about how certain metals in contact with each other cause oxidation and this can lead to erroneous errors on our systems. We were trying to determine the best way to clean them when a technician suggested using a pencil eraser and rubbing the contacts clean. Another claimed that this could cause ESD. Is this possible? Please let me know. - Anonymous, Irvine, CA

Yes, it is possible that the eraser will tribocharge the metal contact(s) and potentially generate an ESD event. Though, this is a popular way to job-shop clean the contacts. You can minimize this threat by grounding the contacts (shunting them) while rubbing them or use a conductive eraser while handling with your bare skin and grounded via a wrist strap. You will first want to rate each board by the most sensitive device on it to determine the class (ESD sensitivity). This will tell you if the board is super sensitive or not. If it’s not that sensitive, you could probably get away with this by applying some simple precautions. The best way to test this is to get an old board, apply the eraser method of cleaning the metal pads and then use a field meter to measure the electric field (voltage) generated from this process. You will want to first zero the meter, then do a before and after reading. If you register anything over 50 Volts, I would recommend this method of cleaning your contacts. Remember, not all boards are the same. Some boards may have super sensitive (class 0) devices embedded on them, made out of different materials (will have a different ranking in the Tribo-Series), etc. as well as the eraser may have different tribo-series rankings/antistatic properties and there each board should be treated as a separate case.

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