New Techniques & Developments in Etching Uniformity

Spring 1988

New Techniques & Developments in Etching Uniformity

Introduction – Although the printed circuit industry has only recenHy become interested in improving the uniformity of etched lines, due to thc need for fine line spacing and controlled impedance circuits, uniformity of etching has long been a major concern for the photo chemical machining industry. In general, etching machines have been made to meet the needs of the printed circuit industry with only minor modifications made 10 these machines for the chemical milling industry. The chemical millers then had to fine tune thisequipmcnllO meet their needs by making such adjustments to the machines as they were able, including changing the angles of individual spray tubes, adjusting the spray pressures of each tube and/or optimizing the oscillation rate of the spray tubes. The purpose of this paper is to present the results of tests done on other variables that have an effect on etch uniformity and show how uniformity might be enhanced beyond what is possible by the above methods.

Donald F. Ball, Chemcut Corporation