IPC-9691 - Revision B : 2016

1 SCOPE

This document is the product of the IPC Electrochemical Migration (ECM) Task Group. It was drafted to provide guidance regarding implementation of the User Guide for the IPC-TM-650, Method 2.6.25, Conductive Anodic Filament (CAF) Resistance and Other Internal Electrochemical Migration Testing to evaluate the effects of mechanical stress, laminate material fracturing, ionic contamination, moisture content prior to press lamination, and other material processing characteristics on formation of conductive paths within laminate material such as conductive anodic filaments (CAF), one specific type of ECM failure mode. This internal ECM test method provides a proven standard for determining the risk of through-hole bias and other internal conductor orientations that result in significant reduction of insulation resistance internally, rather than on the surface of printed boards.

2 BACKGROUND

In recent years, internal electrochemical migration (ECM) liability concerns in the industry have increased as board designs have advanced in terms of decreasing clearances, dimensions and/or higher voltages. ECM failures describe any phenomena that causes internal drop in insulation resistance, including conductive anodic filament (CAF) formation, weak polymer resin bond, hollow fibers, poor wetting of glass reinforcement fibers with resin, foreign material or contamination, rough hole walls, and excessive copper wicking within plated through holes. Temperature, humidity and bias testing of insulation resistance using test coupons is the methodology used to check for these defects. The user of this document is encouraged to become familiar with IPC-9201, Surface Insulation Resistance Handbook to distinguish between internal ECM failures and possible confounding Surface Insulation Resistance (SIR) failures.