Study on surface quality in laser machining of FRP for printed wiring boards - Temperature and heat affected damage in drilling of AFRP

This paper describes the relationship between the temperature and the damage at the hole wall of AFRP (Aramid fiber reinforced plastic) for printed wiring boards (PWB) in laser drilling. First, the temperature is measured by a thermocouple at various positions on the drilled hole wall in laser drilling. Second, we researched the heat affected damage at the hole wall by an optical microscope after drilling. Comparing these results, we clarified the temperature in the hole wall where the heat affected damage occurred. Finally, the thermal transfer model paying attention to the thermal properties of aramid fiber is proposed to predict the heat affected width of the hole wall after laser drilling. It is confirmed that the calculated results by an axisymmetric model were in good agreement with the experimental ones.