Method for making printed circuits

• US 5,148,355 A
• Filed: 10/22/1990
• Issued: 09/15/1992
• Est. Priority Date: 12/24/1988
• Status: Expired due to Fees

• Current Assignee: Technology Applications Company Limited
• Original Assignee: Technology Applications Company Limited
• Inventors: Lowe, John M., Devonport, Joseph
• Primary Examiner(s): GRIFFIN, DONALD
• Application Number:
  US07/585,070
• Time in Patent Office: 694 Days
• Field of Search: 361/311, 361/312, 361/313, 361/323, 361/306, 361/321, 361/410, 174/52 FP, 174/52 PE, 174/68.5, 357/74, 357/81, 357/51, 428/546, 101/466
• US Class Current: 361/778
• CPC Class Codes: H05K 1/095 for polymer thick films, i.e. having a permanent organic polymeric binder
• CPC Class Codes: H05K 1/16 incorporating printed electric components, e.g. printed resistor, capacitor, inductor
• CPC Class Codes: H05K 1/162 incorporating printed capacitors
• CPC Class Codes: H05K 1/167 incorporating printed resistors
• CPC Class Codes: H05K 3/0097 Processing two or more printed circuits simultaneously, e.g. made from a common substrate, or temporarily stacked circuit boards H05K3/0052 takes precedence
• CPC Class Codes: H05K 3/1216 by screen printing or stencil printing
• CPC Class Codes: 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
• CPC Class Codes: H05K 3/4685 Manufacturing of cross-over conductors
• CPC Class Codes: Y10T 428/12014 having metal particles

Abstract

Printed circuits are produced by screen printing or the like to deposit conductors, resistors, capacitors and insulators. Crossover connections are made by covering the conducting portions to be crossed with an insulating material that serves as a base for a printed crossing conductor. The equivalent of multilayer boards can be achieved by printing repeated layers of conductors, components and insulators on the same side of the board, or by printing on two sides of a board. Interconnection between adjacent layers can be made as a part of the printing process. A method of making a printed circuit board comprises applying a first and second coating in a desired pattern to a substrate, the substrate (12) being disposed in a different relationship to coating apparatus used in applying a second coating from the relationship in which it is disposed in applying the first coating. Preferably a number of identical boards are printed on a substrate (12) from which they are subsequently separated. The individual boards are positioned such that the same pattern may be applied when the substrate (12) is presented to coating means in any of a number of orientations each separated from the next by a fixed angle of rotation about an axis (A) at right angles to the substrate (12), the first coating being applied in one such orientation and the second after the screen and substrate respectively have been rotated in opposite direction, (S,B) each through 90°.

Claims

1. A method of producing a contact pad for a printed-circuit board comprising the steps of:

(a) printing a pattern of the contact pad in a conductive ink in a desired location on the printed-circuit board;

(b) curing the conductive ink;

(c) printing the pattern in a carbon ink over the cured conductive ink; and

(d) curing the carbon ink.

2. The method of claim 1 where the steps of printing comprise screen printing the conductive ink and screen printing the carbon ink.

3. A method of manufacturing circuit boards by applying a layer in a desired pattern to a substrate for a printed circuit, the layer being such that a number of identical or substantially identical boards are printed on the substrate and subsequently separated, the boards being positioned such that the same pattern may be applied to the substrate when the substrate is presented to a pattern applying portion of a coating apparatus in any of a number of orientations each separated from the next by a fixed angle of rotation about an axis at right angles to the substrate at a centre of the substrate in one such orientation, the method comprising presenting the substrate to the pattern applying portion of the coating apparatus and applying a first coating in the desired pattern to the substrate, relatively rotating the substrate and pattern applying portion through said fixed angle (or a multiple thereof other than 360°

) so that the substrate and pattern applying portion are again in register and thereafter applying a second coating in the desired pattern to the substrate.

4. A method according to claim 3 wherein the fixed angle is 180°

.

5. A method according to claim 4 wherein the apparatus is a screen printing apparatus and the screen and substrate are rotated in opposite directions each through 90°

.

6. A method according to claim 3 wherein the substrate is a sheet material on which the circuits are printed and from which the individual circuit boards are severed after printing.

7. A method of making a multi-layer printed circuit comprising procuring a substrate and forming conductors on a surface of said substrate and, thereafter, applying over said surface by a printing technique alternating layers of insulating material and conductive material, each of said layers being applied in a preselected pattern for that layer, the patterns of some, at least, of the insulating material layers having openings therein through which material of subsequently applied conductive material layers makes electrical contact with said conductors or with previously applied layers of conductive material at predetermined locations whereby to effect circuit connections and wherein regions of two layers of conductive material are applied with a corresponding region of a layer of insulating material disposed between said regions of two layers of conductive material whereby to provide a capacitor of said printed circuit, and further wherein the conductive material of at least one said layer of conductive material is a resistive ink which is deposited in a controlled amount to serve as a circuit resistor.

8. A method of making a multi-layer printed circuit comprising forming a pattern of conductors and insulators by printing conductive ink, and insulating material on a substrate, leaving exposed parts of said conductors to provide electrical contact or connection regions and protecting said exposed parts by over-printing them with an ink that deposits a carbon layer whereby said exposed parts remain electrically conductive.

9. A printed circuit produced on a single side of a substrate comprising a first set of electrical conductors carried on a surface of the substrate, a layer of an insulating polymer applied on a portion of said surface of the substrate and bridging a first of said electrical conductors on the surface, a bridging electrical conductor carried on the surface of said layer of insulating polymer opposite said surface of the substrate so that it is insulated from said first electrical conductor and in electrical contact with at least a second and a third of said electrical conductors on said surface at opposite sides of said first electrical conductors, a second layer of insulating polymer applied on portions of said surface but which leaves exposed parts of said first set of electrical conductors, and a second set of electrical conductors carried partly on said second layer of insulating polymer but making electrical contact with some of said first set of electrical conductors at said exposed portions, and at least one further layer of insulating polymer applied on said surface and/or on parts at least of previously applied insulating layers and conductors, which leaves exposed parts of at least one set of previously applied electrical conductors.

10. A printed circuit on a single side of a substrate comprising a set of electrical conductors carried on a surface of the substrate or on a layer of insulating polymer applied on the substrate, a layer of insulating polymer applied over said set of electrical conductors and a conducting layer applied over the second-mentioned layer of insulating polymer as a shield against radio-frequency interference or as a ground plane to provide electrical isolation of portions of a circuit from each other.

11. A printed circuit on a substrate comprising at least one set of electrical conductors carried on a surface of the substrate, a layer of an insulating polymer applied on a portion of said surface and bridging a first electrical conductor, a bridging electrical conductor carried on the surface of said bridging layer of insulating polymer so that it is insulated from said first electrical conductor but in electrical contact with at least a second electrical conductor and a third electrical conductor at opposite sides of said first electrical conductor, resistors formed by depositing a controlled amount of resistive ink and capacitors produced by printing conductive layers separated by insulating layers.

12. A multi-layer printed circuit comprising a pattern of conductors and insulators on a substrate with parts of said conductors exposed to provide electrical contact or connection regions, said exposed parts being covered by a carbon layer to protect the exposed parts but ensuring that the exposed parts remain electrically conductive.