An Enhanced Interlayer Construction Strategy for High‐Frequency Copper Clad Laminates: Resolving the Contradiction between Signal Loss and Adhesion

Abstract

In high‐frequency printed circuit boards (PCBs), there is an inherent contradiction between minimizing signal loss and maximizing adhesion strength. To tackle this issue, this work presents a simple approach by developing an enhanced interlayer through a two‐step process involving anodization/APTES (3‐aminopropyltriethoxysilane) treatment. The anodization yields micro/nano oxide structures with low surface roughness, thereby reducing the skin effect. One side of the enhanced interlayer is mechanically anchored and chemically bonded to copper foils, while the other side is coupled with bismaleimide/triazine‐based resins (BT resins), significantly augmenting the adhesion strength. Eight‐layer PCBs manufactured employing this method exhibit an insertion loss of −1.3553 dB in−1 at 32 GHz. Compared to two conventional brown oxide methods, the insertion loss is reduced by 7.80% and 3.24%, respectively, with a more substantial reduction observed at higher frequencies. The peel strength of samples ranges from 0.554 to 0.589 N mm−1, demonstrating maximum enhancements of 34.78% and 164.13% in comparison to the two brown oxide methods, respectively. Moreover, eight‐layer PCBs undergo lead‐free reflow soldering tests, solder float tests, and thermal fatigue tests without encountering any failures. Consequently, the proposed method holds significant practical significance in addressing the challenge associated with low signal loss and high adhesion strength in high‐frequency PCBs.