# US 4,391,845 A · Method of making a membrane switch

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- Number: US 4,391,845 A
- Document ID: US4391845A
- Status: Granted
- Kind: A
- Application number: 06/323,023
- Filed: 1981-11-19
- Granted: 1983-07-05
- Earliest claimed: 1981-11-19
- Assignees: Oak Industries Inc.
- Inventors: Ronald S. Denley
- Web page: https://patentgrep.com/patent/US4391845A

## CPC

- H01H 13/702: with contacts carried by or formed from layers in a multilayer structure, e.g. membrane switches
- H05K 3/245: {Reinforcing conductive patterns made by printing techniques or by other techniques for applying conductive pastes, inks or powders; Reinforcing other conductive patterns by such techniques}
- H01H 13/703: characterised by spacers between contact carrying layers
- H01H 2209/014: composed of different layers; Lubricant in between
- H01H 2211/004: Adhesive
- H01H 2211/01: Ink
- H01H 2227/004: Membrane
- H01H 2229/002: Screen printing
- H05K 2203/1476: Same or similar kind of process performed in phases, e.g. coarse patterning followed by fine patterning
- H01H: ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES (contact cables H01B7/10; electrolytic self-interrupters H01G9/18; emergency protective circuit arrangements H02H; switching by electronic means without contact-making H03K17/00)
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS

## Abstract

This invention relates to a method of fabricating a membrane switch of the type having a substrate, a flexible membrane, electrical conductors formed on the membrane and substrate, and an intervening spacer between the sets of conductors. The conductors include a plurality of switch sites which are in facing relation to define a specific switch. The spacer means comprises a plurality of individual spacer areas which are located remote from the switch sites. The manufacturing method uses a multiple pass screen printing operation. During the first pass a set of conductors is formed from conductive ink on either the membrane or substrate. Also, during the first screening pass a first layer of the spacer areas is formed from the same conductive material as the set of conductors. On subsequent screening passes additional layers are deposited on the spacer areas to build up the thickness of the areas so that the spacer thickness is greater than that of the conductors. The location of the spacer areas and the formation of the first layer of the spacer areas from conductive material permits elimination of one screening pass and subsequent registration problems.

## Claims

### Claim 1

In a method of making a component of a membrane switch in a multiple-pass screen printing process, the membrane switch being of the type having a substrate, a flexible membrane, a first set of electrical conductors on the substrate, a second set of electrical conductors on the membrane, the conductor sets including a plurality of switch sites in facing relation, and spacer means normally holding the conductor sets in spaced, non-contacting relation, the spacer means including a plurality of spacer areas on either the membrane or substrate at locations remote from the first and second sets of electrical conductors, the improved method comprising the steps of:
(a) forming one of the sets of conductors by screening a conductive material on the substrate or membrane in a first screening pass;
(b) forming a first layer of the spacer areas from the conductive material during the first screening pass;
(c) forming additional layers of the spacer areas by subsequent screening passes which deposit material only on the spacer areas so that the spacer means thickness is greater than that of the conductors.

### Claim 2 (depends on 1)

The method of claim 1 wherein the spacer material deposited during said subsequent screening passes is electrically conductive.

### Claim 3 (depends on 1)

The method of claim 1 wherein the spacer material deposited during said subsequent screening passes is electrically non-conductive.

### Claim 4 (depends on 1)

The method of claim 1 further including the step of applying adhesive material to the spacer areas.