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Circular Extrusion Stenciler

IP.com Disclosure Number: IPCOM000085194D
Original Publication Date: 1976-Mar-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 60K

Publishing Venue

IBM

Related People

Bendzel, DS: AUTHOR [+5]

Abstract

The need for being able to apply a controlled amount of solder to each of a large plurality of relatively small pads, located on the bottom of a recessed area of a substrate, is met by the below-described extrusion stenciler. It will be considered in the context of a circular extrusion stenciler, but it will be apparent that the concept can be modified for use on any type of substrate configuration.

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Circular Extrusion Stenciler

The need for being able to apply a controlled amount of solder to each of a large plurality of relatively small pads, located on the bottom of a recessed area of a substrate, is met by the below-described extrusion stenciler. It will be considered in the context of a circular extrusion stenciler, but it will be apparent that the concept can be modified for use on any type of substrate configuration.

The extrusion stenciler is particularly applicable to be used where a squeegee screener does not provide a satisfactory application of solder paste. For example, referring to the figure, if a substrate 11 is recessed, circular and has pads which are located close to an array of pins, which pins might be shorted out if any surplus solder paste is pushed against them, it would be difficult to use a rectilinear squeegee screener, but the present extrusion stenciler works quite well. Another difficulty which might be encountered is the situation where the surface on which the pads are located is not perfectly flat and has a significant warpage therein.

This extrusion stenciler utilizes the concept of the incompressibility of fluids, since the solder paste can be thought of as a fluid. The solder paste is contained in a cylindrical steel cartridge 13 which is fitted with a steel piston 15 that can be driven into the cartridge 13 at a controlled rate by a drive mechanism such as a direct coupled gear head motor 17, thus resulting in a positive displacement extruder. The amount of solder dispensed is directly controlled by the speed of the gear head motor 17.

The shape, thickness and distrib...