Research on the Anti Conductive Anodic Filament Migration in Halogen-free Copper Clad Laminate Substrate
Conductive anodic filament (CAF) migration is a failure mode of printed circuit boards, and it has caused countless catastrophic damages to electronic products. With the increasing density of circuits in electronic products, the spacing between circuit board plating holes is also decreasing, resulting in a significant increase in the number of cases of CAF failure in electronic products. In recent years, electronic materials containing halogens have gradually been banned. A comparative evaluation is conducted between halogen- free FR- 4 substrates and halogen- containing FR- 4 substrates. The two types of specimens use halogen- free substrate and halogen- containing substrate respec-tively, and environmental test are carried out to accelerate the growth of CAF until product failure. Through compara-tive research and analysis of failed samples, it is found that the bonding ability between glass fibers and resin inside the packaging substrate is the fundamental reason that determines the growth rate of CAF. This result means that cau-tion must be exercised when replacing halogen- containing substrates with halogen- free substrates. To avoid CAF fail-ure of fine pitch circuit substrates, it is necessary to improve the bonding strength between glass fibers and resin in the packaging substrate.
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