# US 12,193,155 B2 · Glass cloth, prepreg, and printed wiring board

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- Number: US 12,193,155 B2
- Document ID: US12193155B2
- Status: Granted
- Kind: B2
- Application number: 17/921,842
- Filed: 2021-07-16
- Published: 2023-06-15
- Granted: 2025-01-07
- Earliest claimed: 2020-08-19
- Assignees: Asahi Kasei Kabushiki Kaisha
- Applicants: Asahi Kasei Kabushiki Kaisha
- Inventors: Hiroyuki Honma; Amane Hirose
- Web page: https://patentgrep.com/patent/US12193155B2

## CPC

- H05K 1/0366: {reinforced, e.g. by fibres, fabrics (H05K1/036 takes precedence)}
- B29B 11/16: comprising fillers or reinforcement {(non-woven fabrics per se D04H1/00, D04H3/00)}
- D03D 1/0082: {Fabrics for printed circuit boards}
- D03D 13/008: {characterised by weave density or surface weight}
- D03D 15/267: Glass
- H05K 3/0047: {Drilling of holes}
- B29K 2105/10: {Cords, strands or rovings, e.g.} oriented {cords, strands or rovings}
- D10B 2505/02: Reinforcing materials; Prepregs
- H05K 2201/029: Woven fibrous reinforcement or textile
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- B29B: PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- D03D: WOVEN FABRICS; METHODS OF WEAVING; LOOMS
- B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- D10B: INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES

## Abstract

Provided is a glass cloth obtained by weaving a glass thread, which is made from a plurality of glass filaments, as a warp and weft. The average filament diameter of the glass filaments is 3.0-4.5 μm. The respective weaving densities of the warp and the weft constituting the glass cloth are, independently, 70-130 threads/25 mm. The standard deviation of weft width of the glass cloth is not more than 30 μm. The weft covering ratio R, which is represented by the expression R=Y/(25400/D) (where R is the weft covering ratio, Y is the average weft width, and D is the weft weaving density) satisfies the relational expression 0.50≤R≤0.83.

## Claims

### Claim 1

A glass cloth woven using glass yarns each composed of a plurality of glass filaments as warp yarns and weft yearns, wherein an average filament diameter of the glass filaments is 3.0 to 4.5 μm, weaving densities of the warp yarns and weft yarns constituting the glass cloth are each independently 70 to 130 yarns/25 mm, a standard deviation of a weft yarn width of the glass cloth is 30 μm or less, and in the glass cloth, a weft yarn coverage ratio R, represented by the following formula:
R=Y/(25400/D)
where R is the weft yarn coverage ratio, Y is an average weft yarn width, and D is a weft yarn weaving density, satisfies the following relationship:
0.50≤R≤0.83.

### Claim 2 (depends on 1)

The glass cloth according to claim 1, wherein a number of the glass filaments is 20 to 55.

### Claim 3 (depends on 1)

The glass cloth according to claim 1, wherein a thickness of the glass cloth is 6 to 16 μm.

### Claim 4 (depends on 1)

The glass cloth according to claim 1, wherein the standard deviation of the weft yarn width of the glass cloth is 20 μm or less.

### Claim 5 (depends on 1)

The glass cloth according to claim 1, wherein the standard deviation of the weft yarn width of the glass cloth is 15 μm or less.

### Claim 6 (depends on 1)

The glass cloth according to claim 1, wherein a warp yarn width opening degree calculated from a warp yarn width of the glass cloth, the average filament diameter, and the number of the glass filaments is 75% or more.

### Claim 7 (depends on 1)

A prepreg, comprising the glass cloth according to claim 1, a thermosetting resin, and an inorganic filler.

### Claim 8 (depends on 7)

A printed circuit board comprising the prepreg according to claim 7.

### Claim 9 (depends on 8)

A laser-drilled printed circuit board, wherein the printed circuit board according to claim 8 is subjected to hole machining by laser drilling.

### Claim 10

A method for the production of a glass cloth, comprising a weaving step in which glass yarns each composed of a plurality of glass filaments are woven as warp yarns and weft yarns, and an opening step in which an obtained glass cloth is opened with sprayed water, wherein
in the opening step, pressure of the sprayed water is 0.20 MPa or less, and a warp yarn direction tension is less than 50 N, and
wherein an average filament diameter of the glass filaments is 3.0 to 4.5 μm, weaving densities of the warp yarns and weft yarns constituting the glass cloth are each independently 70 to 130 yarns/25 mm, a standard deviation of a weft yarn width of the glass cloth is 30 μm or less, and in the glass cloth, a weft yarn coverage ratio R, represented by the following formula:
R=Y/(25400/D)
where R is the weft yarn coverage ratio, Y is an average weft yarn width, and D is a weft yarn weaving density, satisfies the following relationship:
0.50≤R≤0.83.