Electrical Activation of Polymer Reny1002H Surface with Laser Irradiation for Molded Interconnect Devices

Polymers Reny 1002H blended with 3% by weight Merck Iriotec 8841 (dicopper hydroxide phosphate) after injection molding was irradiated using a CO2 laser, and followed by copper electroless plating. It has been clearly observed that the surface activation was determined by the interaction level between laser and resin material, namely laser power, scanning speed and line hatching pitch. With increasing laser scanning speed, naturally the modification level was reduced, and electrical resistance was reduced. Line pitch played a similar function to scanning speed. At increasing line hatch spacing, close or larger than the laser spot size, the surface was not able to be modified uniformly. Electrical resistance decreased at a higher modification level with high laser power. SEM analysis disclosed that the copper plated surface was a porous surface structure. The lowest electrical resistance 0.043 Ohms at laser power of 18W, spot size of 200 m, hatching pitch of 150 m and scanning speed of 150 mm/s. The calculated electrical resistivity was 1.62 10 -7 m which was one order of magnitude lower than the bulk copper of 1.72 10 -8 m due to the porous structure disclosed under scan electron microscope (SEM) and the electron dispersive X-ray spectroscopy (EDX) measurements.