# US 6,294,743 B1 · Multilayer print circuit board and the production method of the multilayer print circuit board

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- Number: US 6,294,743 B1
- Document ID: US6294743B1
- Status: Granted
- Kind: B1
- Application number: 09/413,147
- Filed: 1999-10-06
- Granted: 2001-09-25
- Earliest claimed: 1995-04-28
- Assignees: Victor Company of Japan, Ltd.
- Inventors: Tohru Kinoshita
- Web page: https://patentgrep.com/patent/US6294743B1

## CPC

- H05K 3/421: {Blind plated via connections (H05K3/422, H05K3/423 and H05K3/425 take precedence)}
- H05K 3/381: {by special treatment of the substrate}
- H05K 3/4661: {Adding a circuit layer by direct wet plating, e.g. electroless plating; insulating materials adapted therefor (other insulating materials H05K3/387)}
- H05K 3/426: {initial plating of through-holes in substrates without metal}
- H05K 2201/0158: Polyalkene or polyolefin, e.g. polyethylene [PE], polypropylene [PP]
- H05K 2201/0195: Dielectric or adhesive layers comprising a plurality of layers, e.g. in a multilayer structure
- H05K 2201/0209: Inorganic, non-metallic particles
- 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 2201/09827: Tapered, e.g. tapered hole, via or groove
- H05K 2203/0773: Dissolving the filler without dissolving the matrix material; Dissolving the matrix material without dissolving the filler
- H05K 2203/0796: Oxidant in aqueous solution, e.g. permanganate
- Y10S 428/901: Printed circuit
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

The present invention provides a multilayer print circuit board having at least an inner print circuit pattern and an outer print circuit pattern which are laminated on a substrate through an insulation layer and being electrically connected to each other through a blind hole provided in the insulation layer. The insulation layer is composed of a resin insoluble in an oxidization agent and inorganic powder dispersed in the resin. The inorganic powder is soluble in the oxidization agent. The surface of insulation layer and the wall of the blind hole are roughed by the oxidization agent before the outer print circuit pattern is formed on the surface of the insulation layer by plating, whereby the inorganic powder exposed to the oxidization agent is melted therein, resulting in the roughed surface of the insulation layer and the wall of the blind hole.

## Claims

### Claim 1

A multilayer print circuit board comprising:
a substrate being electrically insulative;
a first circuit pattern provided on at least one surface of the substrate;
an insulation layer having an inner insulation layer and an outer insulation layer laminated thereon, said insulation layer being provided on the substrate to overlay the first circuit pattern, wherein the outer insulation layer comprises a resin, calcium carbonate powder and polybutadien as a shock resistant agent, wherein said calcium carbonate powder has an average particle size of 2 to 4 μm being dispersed in the resin, a weight ratio of 15 to 35 weight parts of calcium carbonate powder to 100 weight parts of resin and wherein said polybutadien has a weight ratio of 10 to 20 weight parts of polybutadien to 100 weight parts of resin, and wherein the inner insulation layer comprises a resin;
a blind hole provided in the insulation layer so as to reach the first circuit pattern for exposing a surface of the first circuit pattern;
a second circuit pattern provided on the insulation layer or on the insulation layer and an inner wall of the blind hole so as to electrically connect the first circuit pattern to the second circuit pattern through the blind hole.

### Claim 2 (depends on 1)

The multilayer print board as claimed in claim 1, wherein said blind hole has a V-letter tapered shape which forms an angle of 45° to 85° to the surface of the substrate.

### Claim 3

A multilayer print circuit board comprising:
a substrate being electrically insulative;
a first circuit pattern provided on at least one surface of the substrate;
a first insulation layer having a first inner insulation layer and a first outer insulation layer laminated thereon, the first insulation layer being provided on the substrate to overlay the first circuit pattern;
a first blind hole provided in the first insulation layer so as to reach the first circuit pattern for exposing a surface of the first circuit pattern;
a second circuit pattern provided on the first insulation layer or on the first insulation layer and an inner wall of the first blind hole so as to electrically connect the first circuit pattern to the second circuit pattern through the first blind hole;
a second insulation layer having a second inner insulation layer and a second outer insulation layer laminated thereon, the second insulation layer being provided on the first insulation layer to overlay the second circuit pattern;
a second blind hole provided in the second insulation layer so as to reach the second circuit pattern for exposing a surface of the second circuit pattern;
a third blind hole provided in the second insulation layer and the first insulation layer so as to reach the first circuit pattern for exposing a surface of the first circuit pattern;
a third circuit pattern provided on the second insulation layer or the second insulation layer and an inner wall of the second blind hole so as to electrically connect the second circuit pattern to the third circuit pattern through the second blind hole and provided on the second insulation layer and an inner wall of the third blind hole so as to electrically connect the first circuit pattern to the third circuit pattern through the third blind hole; and
wherein the first outer insulation layer and the second outer insulation layer comprise a resin, calcium carbonate powder and polybutadien as a shock resistant agent, wherein said calcium carbonate powder has an average particle size of 2 to 4 μm being dispersed in the resin, a weight ratio of 15 to 35 weight parts of calcium carbonate powder to 100 weight parts of resin and wherein said polybutadien has a weight ratio of 10 to 20 weight parts of polybutadien to 100 weight parts of resin, and wherein the first inner insulation layer and the second inner insulation layer comprise a resin.

### Claim 4 (depends on 3)

The multilayer print circuit board as claimed in claim 3, wherein the first blind hole, the second blind hole and the third blind hole have a V-letter tapered shape which forms an angle of 45° to 85° to the surface of the substrate.

### Claim 5

A multilayer print circuit board comprising:
a substrate being electrically insulative;
a first circuit pattern provided on at least one surface of the substrate;
a first insulation layer having a first inner insulation layer and a first outer insulation layer laminated thereon, the first insulation layer being provided on the substrate to overlay the first circuit pattern;
a first blind hole provided in the first insulation layer so as to reach the first circuit pattern for exposing a surface of the first circuit pattern;
a second circuit pattern provided on the first insulation layer or on the first insulation layer and an inner wall of the first blind hole so as to electrically connect the first circuit pattern to the second circuit pattern through the first blind hole;
a second insulation layer having a second inner insulation layer and a second outer insulation layer laminated thereon, the second insulation layer being provided on the first insulation layer to overlay the second circuit pattern;
a second blind hole provided in the second insulation layer so as to reach the second circuit pattern for exposing a surface of the second circuit pattern;
a third circuit pattern provided on the second insulation layer or on the second insulation layer and an inner wall of the second blind hole so as to electrically connect the second circuit pattern to the third circuit pattern through the second blind hole;
a third insulation layer having a third inner insulation layer and a third outer insulation layer laminated thereon, the third insulation layer being provided on the second insulation layer to overlay the third circuit pattern;
a third blind hole provided in the third insulation layer so as to reach the third circuit pattern for exposing a surface of the third circuit pattern;
a fourth circuit pattern provided on the third insulation layer or on the third insulation layer and an inner wall of the third blind hole so as to electrically connect the third circuit pattern to the fourth circuit pattern through the third blind hole; and
wherein the first outer insulation layer, the second outer insulation layer and the third outer insulation layer comprise a resin, calcium carbonate powder and polybutadien as a shock resistant agent, wherein said calcium carbonate powder has an average particle size of 2 to 4 μm being dispersed in the resin, a weight ratio of 15 to 35 weight parts of calcium carbonate powder to 100 weight parts of resin and wherein said polybutadien has a weight ratio of 10 to 20 weight parts of polybutadien to 100 weight parts of resin, and wherein the first inner insulation layer, the second inner insulation layer and the third inner insulation layer comprise a resin.

### Claim 6 (depends on 5)

The multilayer print circuit board as claimed in claim 5 further comprising at least one of a fourth blind hole, a fifth blind hole and a sixth blind hole;
wherein the fourth blind hole is provided in the first insulation layer, the second insulation layer and the third insulation layer so as to reach the first circuit pattern for exposing a surface of the first circuit pattern:
wherein the fifth blind hole is provided in the first insulation layer and the second insulation layer so as to reach the first circuit pattern for exposing a surface of the first circuit pattern;
wherein the sixth blind hole is provided in the second insulation layer and the third insulation layer so as to reach the second circuit pattern for exposing a surface of the second circuit pattern; and
wherein, when the fourth blind hole is present, the fourth circuit pattern is further provided on the third insulation layer or on the third insulation layer and an inner wall of the fourth blind bole so as to electrically connect the first circuit pattern to the fourth circuit pattern through the fourth blind hole, wherein, when the fifth blind hole is present, the third circuit pattern is further provided on the second insulation layer or on the second insulation layer and an inner wall of the fifth blind hole so as to electrically connect the first circuit pattern to the third circuit pattern through the fifth blind hole, and wherein, when the sixth blind hole is present, the fourth circuit pattern is further provided on the third insulation layer or on the third insulation layer and an inner wall of the sixth blind hole so as to electrically connect the second circuit pattern to the fourth circuit pattern through the sixth blind hole.

### Claim 7 (depends on 6)

The multilayer print circuit board as claimed in claim 6, wherein the first blind hole, the second blind hole, the third blind hole, the fourth blind hole, the fifth blind hole and the sixth blind hole have a V-letter tapered shape which forms an angle of 45° to 85° to the surface of the substrate.