SMTA International Conference Proceedings

An Innovative Process Indicator For Oxidation Of PCB With OSP Surface Finish (Part 2: Time To Discoloration Correlation With Solderability)

Authors: Eric Hou, DF Chung, and Paul Wang, PhD.
Company: Mitac Computer Shunde Ltd.
Date Published: 10/16/2011   Conference: SMTA International

Abstract: Oxidation on PCB due to shelf life and environment stresses is a severe problem in the soldering process. In this article, the chemical agent of Silver Nitric is used to react with OSP coated-cupper pad. By measuring the time to discoloration, the severity of oxidation can be quantitatively classified and correlated with solderability. Variable such as storage time, temperature & humidity, reflow cycles are adapted as pre-conditioning to emulate shelf life and environment stress and to use as failure precipitation mechanism for oxidation on cupper pad. Using discoloration as an innovative process indicator, the hardening of OSP coating can also being reviewed..

Key Words: 

hole fillet, OSP, PCB, lead-free, Silver Nitric AgNO3, Organic Solderability Preservative (OSP);surface finish, lead-free soldering, process indicator

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