Browse Prior Art Database

Screening Masks and Method of Fabrication

IP.com Disclosure Number: IPCOM000088635D
Original Publication Date: 1977-Jul-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

King, RP: AUTHOR [+2]

Abstract

The screening masks used to form circuit patterns in a conductive paste on a substrate, typically a multilayer ceramic substrate, are relatively complex and normally require supporting tabs to support various portions thereof. The tabs are provided to support portions of the mask and allow the pattern to be completed by flowing the paste beneath the tabs. One technique for forming this type mask is disclosed in the IBM Technical Disclosure Bulletin, Vol. 12, No. 3, August 1976, page 930. In this mask the blank is a laminate formed by adhering various sheets under heat and pressure. However, such laminated masks are relatively expensive and difficulty may be encountered in making them lie flat over the substrate to be printed.

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Screening Masks and Method of Fabrication

The screening masks used to form circuit patterns in a conductive paste on a substrate, typically a multilayer ceramic substrate, are relatively complex and normally require supporting tabs to support various portions thereof. The tabs are provided to support portions of the mask and allow the pattern to be completed by flowing the paste beneath the tabs. One technique for forming this type mask is disclosed in the IBM Technical Disclosure Bulletin, Vol. 12, No. 3, August 1976, page 930. In this mask the blank is a laminate formed by adhering various sheets under heat and pressure. However, such laminated masks are relatively expensive and difficulty may be encountered in making them lie flat over the substrate to be printed.

In this method a screening mask having the general configuration shown in Fig. 1 is fabricated. A blank sheet of molybdenum 10, having a thickness of at least 1.5 mils, is cleaned and resist layers 12 and 14 applied, as indicated in Fig.
2. The layer 14 on the top side is then exposed to a mesh-type pattern of the configuration shown in Fig. 1, resulting in a plurality of closely spaced apertures
16. The resist layer 12 on the bottom side of the molybdenum blank 10 is exposed to the desired stripe and via pattern of the type shown also in Fig. 1, resulting in apertures 18 after the resist layers have been developed.

After the layers 12 and 14 have been developed, the composite sheet is etched in pota...