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
