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Producing Printed Circuits Disclosure Number: IPCOM000094249D
Original Publication Date: 1966-Aug-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 44K

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Pittwood, DG: AUTHOR [+1]


Additive type printed circuits are produced by this intaglio or transfer plate process.

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Producing Printed Circuits

Additive type printed circuits are produced by this intaglio or transfer plate process.

Stainless steel plate 10 is photoetched to leave the desired circuit pattern raised relative to etched-out negative pattern areas.

The entire contoured work surface of plate 10 is electroplated with copper 11, drawing A, layed up with plastic-impregnated glass cloth sheets 12 between platens 13 and 14 of a press, and laminated at a suitable temperature and pressure to bond insulating sheets 12 to the electro formed surface of the plate. Plate 10 is then stripped off for re-use, leaving a copper-clad laminate with the desired circuit pattern in relief, drawing B. The laminate is then passed through an abrasive machine to grind off the raised negative pattern portions, drawing C, leaving the desired circuit board.

The advantage of this process is that the entire surface of the etched transfer plate is electroplated. This eliminates the need for applying plated resist or nonconductive fillers in the negative circuit areas. Further, the continuous surface of the electroform aids in containing resin flow during lamination. Thus, resin does not squeeze onto the surface of the transfer plate, causing a subsequent cleaning or plating problem.


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