Investigation of the chip adhesion mechanisms in micro-drilling of high ceramic-content particle-filled GFRPs

Abstract

Glass-fiber reinforced polymers (GFRP) are widely used for printed circuit boards (PCBs) in automotive and aircraft structural applications. The performance of micro-drilling in high ceramic-content particle-filled GFRP heavily influences the signal transmission quality and speed available from these PCBs. Chip adhesion is one of the biggest obstacles to high-performance micro-drilling especially for holes with large depth-to-diameter ratios. This paper offers the first study of the chip adhesion characteristics and formation mechanisms seen when micro-drilling ceramic particle-filled GFRP components, which is the substrate material of PCBs. A direct-contact temperature measurement method is presented to measure the temperatures seen when drilling the laminated composite material. The effects of processing parameters on drilling temperatures and chip adhesion were investigated. A method to control chip adhesion is suggested. The results show that chip adhesion can be divided into four stages. Effective measures to reduce chip adhesion include reducing the drill speed, appropriately increasing the feed rate, and, controlling the number of drilled holes before the drill is sharpened. Also, the use of cold forced air can aid heat dissipation and effective chip extraction. As a result, the chip adhesion was reduced.