Production method of thin film resistance element formed on printed circuit board, and thin film resistance element employing the method

• US 6,411,194 B2
• Filed: 02/27/2001
• Issued: 06/25/2002
• Est. Priority Date: 03/30/2000
• Status: Expired due to Term

• Current Assignee: Rakuten, Inc. (Rakuten Group, Inc.)
• Original Assignee: Victor Company of Japan Limited (JVC Kenwood Corporation)
• Inventors: Segawa, Keiji, Otsuki, Mitsuru, Shindoh, Motoshi
• Primary Examiner(s): Enad, Elvin
• Assistant Examiner(s): Lee, Kyung S.
• Application Number:
  US09/794,596
• Publication Number:
  US 20010026211A1
• Time in Patent Office: 483 Days
• Field of Search: 338/308, 338/309, 338/312, 338/314, 338/318, 338/319, 338/327, 338/328, 338/320, 338/260, 296/101, 296/102
• US Class Current: 338/308
• CPC Class Codes: H01C 17/12 by sputtering
• CPC Class Codes: H05K 1/0206 by printed thermal vias
• CPC Class Codes: H05K 1/165 incorporating printed inductors
• CPC Class Codes: H05K 1/167 incorporating printed resistors
• CPC Class Codes: H05K 2201/0175 Inorganic, non-metallic layer, e.g. resist or dielectric for printed capacitor
• CPC Class Codes: H05K 2201/0179 Thin film deposited insulating layer, e.g. inorganic layer for printed capacitor
• CPC Class Codes: H05K 2201/0187 with regions of different dielectrics in the same layer, e.g. in a printed capacitor for locally changing the dielectric properties
• CPC Class Codes: H05K 2201/0209 Inorganic, non-metallic particles
• CPC Class Codes: H05K 2201/0317 Thin film conductor layer; Thin film passive component
• CPC Class Codes: H05K 2201/09509 Blind vias, i.e. vias having one side closed
• CPC Class Codes: H05K 2201/09763 Printed component having superposed conductors, but integrated in one circuit layer
• CPC Class Codes: H05K 2203/0361 Stripping a part of an upper metal layer to expose a lower metal layer, e.g. by etching or using a laser
• CPC Class Codes: H05K 3/388 by the use of a metallic or inorganic thin film adhesion layer
• CPC Class Codes: H05K 3/4644 by building the multilayer layer by layer, i.e. build-up multilayer circuits making via holes in the insulating layers H05K3/0011; special circuit boards as base or core whereon the multilayer is built H05K3/4602
• CPC Class Codes: Y10T 29/49082 Resistor making

Abstract

The invention provides a production method capable of forming a thin film resistance element having a thickness and a shape controlled in a high accuracy in a printed circuit board. The production method of a thin film resistance element formed on a printed circuit board, has the steps of forming a thin film resistance layer having a predetermined thickness on the printed circuit board through an insulation layer by a dry process used in producing a semiconductor, forming an electrically conductive layer on the thin resistance layer, and etching the electrically conductive layer selectively so as to make, at least, a pair of electrically conductive pads, resulting in the thin film resistance element having a predetermined value of resistivity between the pair of electrically conductive pads. Thereby, it is possible to form the thin film resistance element having a thickness and a shape controlled in a high accuracy on the printed circuit board.

Claims

1. A production method of a thin film resistance element formed on a printed circuit board having an insulation layer, comprising the steps of:

roughening or activating a surface of the insulation layer by a dry process used in producing a semiconductor;

forming a thin film resistance layer having a predetermined thickness on the roughened or activated surface of the insulation layer by a dry process used in producing a semiconductor and in a vacuum such that the insulation layer is not oxidized during the formation of the thin film resistance layer;

forming an electrically conductive layer on the thin film resistance layer;

forming a first copper layer on the thin film resistance layer by a sputtering method;

forming a second copper layer on the first copper layer by an electric plating method; and

etching the electrically conductive layer selectively so as to make, at least, a pair of electrically conductive pads, resulting in the thin film resistance element having a predetermined value of resistivity between the pair of electrically conductive pads.

2. The production method as claimed in claim 1, wherein the thin film resistance layer is formed in a process of fabricating a build up printed circuit board that has multi-layers alternately stacked with an inner insulation layer and an inner electrically conductive layer having an inner circuit pattern on a substrate.

3. The production method as claimed in claim 2, further comprising the step of forming a via hole in the inner insulation layer so as to electrically connected to the thin film resistance layer to the inner electrically conductive layer through the via hole.

4. A printed circuit board having a thin film resistance element produced by the production method comprising the steps of:

roughening or activating a surface of the insulation layer by a dry process used in producing a semiconductor;

forming a thin film resistance layer having a predetermined thickness of the insulation layer by a dry process used in producing a semiconductor and in a vacuum such that the insulation layer is not oxidized during the formation of the insulating layer;

forming an electrically conductive layer on the thin film resistance layer;

forming a first copper layer on the thin film resistance layer by a sputtering method;

forming a second copper layer on the first copper layer by an electrical plating method; and

etching the electrically conductive layer selectively so as to make at least a pair of electrically conductive pads, resulting in the thin film resistance element having a predetermined value of resistivity between the pair of electrically conductive pads.

5. A build up printed circuit board having a thin film resistance element formed by the production method as claimed in claim 4, wherein the thin film resistance element is formed in a process of fabricating the build up printed circuit board that has multi-layers alternatively stacked with an inner insulation layer and an inner electrically conductive layer having an inner circuit pattern on a substrate.

6. The build up printed circuit board having a thin film resistance element as claimed in claim 5, the production method further comprising the step of forming a via hole in the inner insulation layer so as to electrically connected to the thin film resistance layer to the inner electrically conductive layer through the via hole.