GB690696A - Improvements relating to the manufacture of coated strip material for use in making eectric circuit components or printed circuits - Google Patents

Abstract

690,696. Automatic thickness control systems. STRONG, H. V., and EISLER, P. March 16, 1950 [March 17, 1949], No. 7299/49. Class 38 (iv). [Also in Group XL (b)] In order to maintain a constant thickness of coating 78 on a flexible strip 71 in the manufacture of electric circuit components for printed circuits, sources of light, radioactivity, or X-rays 72, 73, are directed on to the strip and the amount of radiation emanating from, transmitted through or reflected by the coating, being a function of the thickness thereof, is detected by radiation sensitive devices 75, 76 the outputs from which are differentially applied to an instrument 77 which through a controller 79 adjusts an applicator 74 to maintain the thickness of the coating constant, irrespective of the thickness of the strip. The control may also be effected manually. In other embodiments the coating itself may form the source of radiation and is then impregnated with dyes or pigments, or with radio-active material, the latter being driven off by heat after coating. one of the sources 72, 73 may be omitted if desired, the strip then being moved round the remaining source and a single detector may be rotated round an axis passing through the source. If two sources are used a differential detector 80 may be provided to compensate for radiation differences between sources 72, 73. Specification 690,328, [Group XXXVI], is referred to. Specification 639,111 also is referred to in the Provisional Specification.