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Test Specimen for Plasma Etch Process

IP.com Disclosure Number: IPCOM000049552D
Original Publication Date: 1982-Jun-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Ruh, WD: AUTHOR

Abstract

A two-piece test specimen is used to evaluate the effectiveness of a known plasma etching process for removing epoxy smear in the vias of a laminated glass-epoxy printed circuit board (PCB).

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Test Specimen for Plasma Etch Process

A two-piece test specimen is used to evaluate the effectiveness of a known plasma etching process for removing epoxy smear in the vias of a laminated glass-epoxy printed circuit board (PCB).

The two-piece specimen 1-2 (Fig. 1) is inserted and held in position by wedges W in cutout C provided in a sample PCB of the type to be investigated. The specimen pieces 1 and 2 are made of the same material as the PCB. The first piece 1 acts as a dummy, and its surface 3 is highly polished. The second piece 2 acts as a mask, and its surface 4, which is in contact with surface 3, is also highly polished. In addition, surface 4 has plural elongated parallel channels or grooves 5 with dimensions compatible to the dimensions of via holes of the board type being investigated, as measured prior to the smear-removal etching process. Thus, prior to the etching process and with the surfaces 3 and 4 in contact, the grooves 5 provide simulated vias in the specimen 1-2. After subjection to the aforementioned known plasma etch, grooves 6 (Fig. 2) in the contacting surface 3 of the dummy piece 1 are formed through and juxtaposed to the open channels 5 of mask piece 2.

Thereafter, the pieces 1-2 are removed from the cutout C and separated. By means of a surface analyzer (not shown) the depth of the grooves 6 are measured. It can be shown that the obtained measurements, which are associated with the formation of the grooves 6 by the etching process, are...