FROM MECHANICAL ADHESION TO CHEMICAL ADHESION: CHALLENGES IN OBTAINING SUFFICIENT ADHESION BETWEEN ELECTROLESS COPPER AND DIELECTRICS

摘要

The ever-demanding world of portable electronics keeps pushing the technology required in the miniaturization of circuitry on PCBs. The current manufacturing methods of high density copper circuitry to dielectric limit the minimum width of the lines to 10μm as adhesion is strongly correlated to the roughness of the dielectric (via mechanical means). CovaBond a recently developed process, will allow for smaller line widths (down to 5μm) as this allows for higher adhesion between the dielectric and copper at lower roughness values (enhanced mechanical). For even smaller line widths (<5μm), adhesion by mechanical methods may not be viable and alternative methods (chemical bonds) will be necessary. This paper will review the current process for treating the dielectric surface for the subsequent deposition of electroless copper and will compare it to new treatments. The data presented will show that improved copper-to-dielectric adhesion with minimal roughening can be achieved. The origin of the improvement in adhesion is attributed to chemical bonding as no roughening is observed on the dielectric.