# US 12,120,861 B2 · Electromagnetic wave shielding film and shielded printed wiring board

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- Number: US 12,120,861 B2
- Document ID: US12120861B2
- Status: Granted
- Kind: B2
- Application number: 18/044,529
- Filed: 2021-09-22
- Published: 2023-10-19
- Granted: 2024-10-15
- Earliest claimed: 2020-09-23
- Assignees: Tatsuta Electric Wire & Cable Co., Ltd.
- Applicants: Tatsuta Electric Wire & Cable Co., Ltd.
- Inventors: Yoshiharu Yanagi; Hiroshi Tajima
- Web page: https://patentgrep.com/patent/US12120861B2

## CPC

- H05K 1/0216: {Reduction of cross-talk, noise or electromagnetic interference (grounding H05K1/0215)}
- H05K 9/0088: {comprising a plurality of shielding layers; combining different shielding material structure}
- B32B 7/025: Electric or magnetic properties
- B32B 27/18: characterised by the use of special additives
- C09J 7/30: characterised by the adhesive composition
- C09J 9/02: Electrically-conducting adhesives
- C09J 201/00: Adhesives based on unspecified macromolecular compounds
- H05K 1/023: {using auxiliary mounted passive components or auxiliary substances (printed passive components H05K1/16)}
- H05K 1/0268: {for electrical inspection or testing}
- H05K 9/0083: {comprising electro-conductive non-fibrous particles embedded in an electrically insulating supporting structure, e.g. powder, flakes, whiskers (H05K9/0086 takes precedence)}
- H05K 2201/0215: Metallic fillers
- H05K 2201/0245: Flakes, flat particles or lamellar particles
- H05K 2201/0272: Mixed conductive particles, i.e. using different conductive particles, e.g. differing in shape
- H05K 2201/0715: provided by an outer layer of PCB
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- C09J: ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES (preparation of glue or gelatine C09H)

## Abstract

An electromagnetic wave shielding film that can be thinned, and has high peel strength, electroconductivity, shielding properties, and flex resistance and conformability to a step is provided. An electromagnetic wave shielding film of the present invention is an electromagnetic wave shielding film including: an electroconductive adhesive layer containing electroconductive particles and an adhesive resin composition, wherein the electroconductive particles contain flaky electroconductive particles and spherical electroconductive particles, the average particle size of the spherical electroconductive particles is 1 to 10 μm, the content of the flaky electroconductive particles and the spherical electroconductive particles in the electroconductive adhesive layer is 70 to 80% by weight, the weight ratio of the flaky electroconductive particles to the spherical electroconductive particles, [flaky electroconductive particles]/[spherical electroconductive particles], is 6/4 to 8/2, and the thickness of the electroconductive adhesive layer is 5 to 20 μm.

## Claims

### Claim 1

An electromagnetic wave shielding film comprising:
an electroconductive adhesive layer comprising electroconductive particles and an adhesive resin composition,
the electroconductive particles comprising flaky electroconductive particles and spherical electroconductive particles,
an average particle size of the spherical electroconductive particles being 1 to 10 μm,
a content of the flaky electroconductive particles and the spherical electroconductive particles in the electroconductive adhesive layer being 70 to 80% by weight,
a weight ratio of the flaky electroconductive particles to the spherical electroconductive particles, [flaky electroconductive particles]/[spherical electroconductive particles], being 6/4 to 8/2,
a thickness of the electroconductive adhesive layer being 5 to 20 μm, and
the electroconductive particles being copper and/or silver-coated copper.

### Claim 2 (depends on 1)

The electromagnetic wave shielding film according to claim 1, further comprising an insulating layer.

### Claim 3 (depends on 2)

The electromagnetic wave shielding film according to claim 2, further comprising a metal layer between the insulating layer and the electroconductive adhesive layer.

### Claim 4

A shielded printed wiring board, comprising:
a printed wiring board including a base film, a printed circuit arranged on the base film, and a coverlay arranged so as to cover the printed circuit; and
an electromagnetic wave shielding film including an electroconductive adhesive layer containing electroconductive particles and an adhesive resin composition,
the electromagnetic wave shielding film being arranged on the printed wiring board such that the electroconductive adhesive layer is in contact with the coverlay,
the electroconductive particles including flaky electroconductive particles and spherical electroconductive particles,
an average particle size of the spherical electroconductive particles being 1 to 10 μm,
a content of the flaky electroconductive particles and the spherical electroconductive particles in the electroconductive adhesive layer being 70 to 80% by weight,
a weight ratio of the flaky electroconductive particles to the spherical electroconductive particles, [flaky electroconductive particles]/[spherical electroconductive particles], being 6/4 to 8/2,
a thickness of the electroconductive adhesive layer being 5 to 20 μm, and
the electroconductive particles being copper and/or silver-coated copper.

### Claim 5 (depends on 4)

The shielded printed wiring board according to claim 4,
wherein the printed circuit comprises a ground circuit,
the coverlay has an opening formed therein for exposing the ground circuit, and
the electroconductive adhesive layer fills the opening and is contact with the ground circuit.

### Claim 6 (depends on 4)

The shielded printed wiring board according to claim 4,
wherein an insulating layer is arranged on a side of the electroconductive adhesive layer not in contact with the coverlay.

### Claim 7 (depends on 6)

The shielded printed wiring board according to claim 6,
wherein a metal layer is arranged between the electroconductive adhesive layer and the insulating layer.