Gas Release
Release of trapped moisture and volatile organic compounds from internal printed circuit board layers occurs when the board undergoes high-temperature processing. This physical behavior, known as outgassing mechanics, is driven by the expansion of trapped gases through microscopic cracks or pathways in the copper plating. It is especially pronounced during soldering, when temperatures exceed two hundred degrees Celsius.
This pressure buildup can damage the surrounding board structure.
Defect Generation
The escape of vaporized material into molten solder creates blowholes and pinholes that compromise solder joint integrity. If the gas escape occurs just as the solder begins to solidify, it leaves behind open cavities on the surface or internal pockets. These voids reduce the mechanical strength of the solder joint and increase the risk of electrical open circuits.
Thin copper plating in via holes is particularly vulnerable to this gas expansion because it cannot withstand the internal steam pressure. This structural weakness leads to trace cracking.
Remediation Strategy
Pre-baking circuit boards before assembly drives out moisture from the epoxy glass matrix to prevent gas release. Heating the boards at one hundred and twenty degrees Celsius for several hours ensures a dry substrate. Maintaining copper plating thicknesses above twenty-five micrometers in via walls also helps contain internal vapors.
These steps eliminate solder defects.
