# US 5,347,712 A · Method for manufacturing a multilayer wiring board

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- Number: US 5,347,712 A
- Document ID: US5347712A
- Status: Granted
- Kind: A
- Application number: 08/076,191
- Filed: 1993-06-14
- Granted: 1994-09-20
- Earliest claimed: 1990-05-25
- Assignees: Sony Corporation
- Inventors: Nobuyuki Yasuda; Toshio Tamura; Hiroshi Toi; Akio Mishima
- Web page: https://patentgrep.com/patent/US5347712A

## CPC

- H05K 3/0044: {Mechanical working of the substrate, e.g. drilling or punching (H05K3/0008 takes precedence)}
- H05K 1/115: {Via connections; Lands around holes or via connections (H05K1/112 takes precedence)}
- H05K 3/4652: {Adding a circuit layer by laminating a metal foil or a preformed metal foil pattern (H05K3/4647 takes precedence)}
- H05K 3/429: {Plated through-holes specially for multilayer circuits, e.g. having connections to inner circuit layers}
- H05K 2201/0355: Metal foils
- H05K 2201/0394: Conductor crossing over a hole in the substrate or a gap between two separate substrate parts
- H05K 2201/09509: Blind vias, i.e. vias having one side closed
- H05K 2201/09518: Deep blind vias, i.e. blind vias connecting the surface circuit to circuit layers deeper than the first buried circuit layer
- H05K 2201/09809: Coaxial layout
- H05K 2201/09845: Stepped hole, via, edge, bump or conductor
- H05K 2203/025: Abrading, e.g. grinding or sand blasting
- H05K 2203/0554: Metal used as mask for etching vias, e.g. by laser ablation
- Y10T 29/49155: Manufacturing circuit on or in base
- Y10T 29/49165: by forming conductive walled aperture in base
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A multilayer wiring board and a method for manufacturing the same are disclosed. The wiring board comprises an insulating substrate having a first and second conductor layers formed on major surfaces of the insulating substrate, a blind hole formed through the first conductor layer and the insulating substrate to expose the second conductor layer at the bottom of the blind hole, and a connecting conductor provided to cover the exposed surface of the second conductor layer wall portion of the blind hole and the first conductor layer. Since the connecting conductor and the second conductor are made in surface contact, connection reliability is very much improved. The blind hole is made by blasting a fine abrasive powder beam to selectively remove the insulating substrate. The end of selective removal can be easily controlled by the difference of working speed against the insulating substrate and the conductor layer to successfully expose the second conductor layer at the bottom of the blind hole.

## Claims

### Claim 1

A method for manufacturing a multilayer wiring board comprising the steps of;
a) forming a first conductor layer on a second major surface of an insulating substrate,
b) forming a patterned mask which is resistant to the subsequent etching on a first major surface of said insulating substrate,
c) blasting a fine abrasive powder from the side of said first major surface to selectively remove said insulating substrate until said first conductor layer is exposed at a bottom of a hole portion thus formed, and
d) forming a second conductor layer to cover side wall surface of said hole portion and said first conductor exposed at said bottom of said hole portion.

### Claim 2 (depends on 1)

A method according to claim 1, wherein said patterned mask is a third conductor layer formed on said first major surface of said insulating substrate.

### Claim 3 (depends on 1)

A method according to claim 1, wherein said patterned mask is a third conductor layer formed on said first major surface of said insulating layer and an elastic resinous material layer formed on said third conductor layer.

### Claim 4 (depends on 1)

A method according to claim 1, wherein said fine abrasive powder has an average powder diameter not exceeding 16 .mu.m.

### Claim 5 (depends on 1)

A method according to claim 1, wherein said fine abrasive powder has hardness larger than a hardness of said insulating substrate.