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Technique for Blocking Paste Ingress Into Substrate Apertures

IP.com Disclosure Number: IPCOM000039846D
Original Publication Date: 1987-Aug-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 87K

Publishing Venue

IBM

Related People

Harris, FW: AUTHOR

Abstract

In the manufacture of printed circuit substrates having holes for pins, masks are used to screen paste or ink onto preselected portions of the substrates. Often it is necessary to deposit paste or ink in an area around a pin hole, such as a blended radius. With known methods, apertures were formed above the blended radius and paste or ink was squeezed through the aperture. Often, some of the paste or ink flowed into the hole and thereby plugged or reduced the size of the hole. (Image Omitted) The deposition of paste or ink within the hole can be avoided by providing a raised portion on the mask in correspondence with the hole. The figures show three techniques for forming the desired raised portion. In Fig. 1, an epoxy dot 1 is deposited at the center of the doughnut-shaped portion 3 of mask 2.

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Technique for Blocking Paste Ingress Into Substrate Apertures

In the manufacture of printed circuit substrates having holes for pins, masks are used to screen paste or ink onto preselected portions of the substrates. Often it is necessary to deposit paste or ink in an area around a pin hole, such as a blended radius. With known methods, apertures were formed above the blended radius and paste or ink was squeezed through the aperture. Often, some of the paste or ink flowed into the hole and thereby plugged or reduced the size of the hole.

(Image Omitted)

The deposition of paste or ink within the hole can be avoided by providing a raised portion on the mask in correspondence with the hole. The figures show three techniques for forming the desired raised portion. In Fig. 1, an epoxy dot 1 is deposited at the center of the doughnut-shaped portion 3 of mask 2. Portion 3 corresponds to an area extending across the face of hole 4 in substrate 9. When paste 5 is squeezed onto the surface of mask 2 and through holes 6 in mask 2, dot 1 prevents the intrusion of paste 5 into hole 4 by blocking the entrance to hole 4. Figs. 2 and 3 show alternative techniques for forming dots on the face of mask 2. In Fig. 2, dot 7 is formed by providing an epoxy deposition larger than required and grinding the deposition down to the size necessary to block hole 4. In Fig. 3, dot 8 is formed during an etch process used to manufacture the mask. A photo/etch process is used to simultaneously e...