Research on Surface Roughness of Die Steel in Micro-Etching

In this study, the 300 µm width micro-channel was manufactured by spray etching method. The surface roughness was analyzed by Laser scanning con-focal microscope. The relationship of the surface roughness and etching factor such as spray etching pressure, mask gap and time had been studied. The results show that the surface roughness increases initially, and then reduces with the size of mask gap. While the roughness increases as the spraying pressure increases. The etching time plays slightly effect on roughness for it has no impact on the etch uniformity as mask gap and spray pressure do.

Improvement in Etching Factor of Micro Patterns by Controlling Residual Stress of Copper Thin Foil

The effectiveness of residual stress on forming copper patterns of printed circuit board was investigated during applied thermal conditions. Generally, the electrolytic copper foil showed a compressive residual stress about -55~-60MPa as received, which easily caused to form copper patterns irregularly when the pattern was etched finely. The compressive residual stress was relaxed with applying heat-treatment for a few hours. However, we observed that the compressed residual stress of copper foil tended to be relaxed, constant, and compressed again during heat-treatment process, which is mainly considered as that the grain of copper is grown restrictively within a Cu thin foil layer. We suggested a quantitative method for controlling grain size, grain distribution and relaxing stress of copper foil, which was very helpful for increasing an etching factor to decrease pattern width.

Effectiveness of Residual Stress on Forming Copper Patterns of Printed Circuit Board

The effectiveness of residual stress on forming copper patterns of printed circuit board was investigated during applied thermal conditions. Generally, the electrolytic copper foil showed a compressive residual stress about -54MPa as received, which easily caused to form copper patterns irregularly. We verified the compressive residual stress was relaxed with applying thermal conditions under 200°C for a few hours. And also, we observed that the compressive residual stress of copper foil tended to be relaxed, constant, and compressive again during heating times at each temperature. The relationships between residual stress and etching factor of copper pattern were analyzed in this works.