# US 11,452,216 B2 · Method for manufacturing multilayer printed wiring board

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- Number: US 11,452,216 B2
- Document ID: US11452216B2
- Status: Granted
- Kind: B2
- Application number: 16/632,790
- Filed: 2018-07-25
- Published: 2021-05-27
- Granted: 2022-09-20
- Earliest claimed: 2017-07-25
- Assignees: Panasonic Intellectual Property Management Co., Ltd.
- Applicants: Panasonic Intellectual Property Management Co., Ltd.
- Inventors: Kazuki Matsumura; Yohsuke Ishikawa; Koji Kishino
- Web page: https://patentgrep.com/patent/US11452216B2

## CPC

- B32B 37/0015: {to avoid warp or curl}
- H05K 3/4673: {Application methods or materials of intermediate insulating layers not specially adapted to any one of the previous methods of adding a circuit layer (similar methods for protective coatings H05K3/28)}
- B29C 43/20: Making multilayered or multicoloured articles {(B29C43/14 takes precedence)}
- B29C 70/088: {and with one or more layers of non-plastics material or non-specified material, e.g. supports}
- B29C 70/865: {completely encapsulated}
- B29C 70/885: {with incorporated metallic wires, nets, films or plates (as lost heating elements B29C35/0272, B29C61/0625)}
- B32B 15/02: {Layer formed of wires, e.g. mesh}
- B32B 15/092: comprising epoxy resins
- B32B 15/20: comprising aluminium or copper {(B32B15/016 and B32B15/017 take precedence)}
- B32B 27/20: using fillers, pigments, thixotroping agents
- B32B 27/38: comprising epoxy resins
- B32B 37/06: characterised by the heating method
- B32B 37/10: characterised by the pressing technique, e.g. using action of vacuum or fluid pressure
- C09J 5/06: involving heating of the applied adhesive
- C09J 7/10: without carriers
- C09J 7/35: Heat-activated
- C09J 11/02: Non-macromolecular additives
- H05K 1/0271: {Arrangements for reducing stress or warp in rigid printed circuit boards, e.g. caused by loads, vibrations or differences in thermal expansion}
- H05K 1/0366: {reinforced, e.g. by fibres, fabrics (H05K1/036 takes precedence)}
- H05K 3/022: {Processes for manufacturing precursors of printed circuits, i.e. copper-clad substrates}
- B29C 70/42: for producing articles of definite length, i.e. discrete articles
- B29K 2063/00: Use of {EP, i.e.} epoxy resins {or derivatives thereof}, as moulding material
- B29L 2031/3425: {Printed circuits}
- B32B 37/144: {using layers with different mechanical or chemical conditions or properties, e.g. layers with different thermal shrinkage, layers under tension during bonding (constructional features for tensioning B32B38/1825)}
- B32B 38/10: Removing layers, or parts of layers, mechanically or chemically
- B32B 2305/076: Prepregs
- B32B 2307/206: Insulating
- B32B 2311/00: Metals, their alloys or their compounds
- B32B 2311/12: Copper
- B32B 2363/00: Epoxy resins
- B32B 2457/08: PCBs, i.e. printed circuit boards
- C09J 2203/326: for bonding electronic components such as wafers, chips or semiconductors
- C09J 2400/26: Presence of textile or fabric
- C09J 2463/00: Presence of epoxy resin
- H05K 1/0373: {containing additives, e.g. fillers (H05K1/036 takes precedence)}
- H05K 3/4655: {by using a laminate characterized by the insulating layer (general-purpose insulating materials H05K1/03, H05K3/4673)}
- H05K 2201/068: wherein the coefficient of thermal expansion is important
- H05K 2203/065: Binding insulating layers without adhesive, e.g. by local heating or welding, before lamination of the whole PCB
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- 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)
- 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
- B29L: INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES

## Abstract

A first stack is formed by stacking a first sheet of metal foil, a first prepreg, and a second sheet of metal foil, one on top of another. The first prepreg is thermally cured by thermally pressing these members to make a double-sided metal-clad laminate. Conductor wiring is formed by partially removing the first sheet of metal foil from the double-sided metal-clad laminate to make a printed wiring board. After a third sheet of metal foil has been preheated, the conductor wiring of the printed wiring board, a second prepreg, and the third sheet of metal foil are stacked one on top of another and thermally pressed together. The first insulating layer has a lower linear expansion coefficient than any of the first sheet of metal foil or the second sheet of metal foil does.

## Claims

### Claim 1

A method for manufacturing a multilayer printed wiring board, the method comprising:
forming a first stack by stacking a first sheet of metal foil, a first prepreg, and a second sheet of metal foil, one on top of another such that the first prepreg is interposed between the first sheet of metal foil and the second sheet of metal foil;
forming a first insulating layer from the first prepreg by thermally pressing the first stack and thereby thermally curing the first prepreg to make a double-sided metal-clad laminate in which the second sheet of metal foil, the first insulating layer, and the first sheet of metal foil are stacked one on top of another in this order;
forming conductor wiring by partially removing the first sheet of metal foil from the double-sided metal-clad laminate to make a printed wiring board in which the second sheet of metal foil, the first insulating layer, and the conductor wiring are stacked one on top of another in this order;
forming a second stack by stacking the conductor wiring of the printed wiring board, a second prepreg, and a third sheet of metal foil, one on top of another such that the second prepreg is interposed between the conductor wiring of the printed wiring board and the third sheet of metal foil; and
forming a second insulating layer from the second prepreg by thermally pressing the second stack without preheating and thereby thermally curing the second prepreg,
in forming the second stack, the third sheet of metal foil after having been preheated being stacked on the second prepreg without preheating the printed wiring board and the second prepreg,
the first insulating layer having a lower linear expansion coefficient than any of the first sheet of metal foil or the second sheet of metal foil does.

### Claim 2 (depends on 1)

The method of claim 1,
wherein the first insulating layer has a thickness of 50 μm or less.

### Claim 3 (depends on 1)

The method of claim 1,
wherein the first insulating layer has a linear expansion coefficient falling within a range from 5 ppm/K to 17 ppm/K.

### Claim 4 (depends on 1)

The method of claim 1,
wherein the third sheet of metal foil has a thickness falling within a range from 0.002 mm to 0.035 mm.

### Claim 5 (depends on 1)

The method of claim 1,
wherein the second insulating layer has a lower linear expansion coefficient than the third sheet of metal foil does.

### Claim 6 (depends on 1)

The method of claim 1,
wherein the second insulating layer has a linear expansion coefficient falling within a range from 5 ppm/K to 17 ppm/K.

### Claim 7 (depends on 1)

The method of claim 1,
wherein the first prepreg includes a thermosetting resin composition and a fibrous base material,
the thermosetting resin composition contains an inorganic filler, and
a subtotal of the inorganic filler, contained in the thermosetting resin composition, and the fibrous base material accounts for 50% by mass to 85% by mass of a grand total of the thermosetting resin composition and the fibrous base material.

### Claim 8 (depends on 1)

The method of claim 1,
wherein the multilayer printed wiring board has a degree of warp greater than −35 mm and equal to or less than 2 mm.

### Claim 9 (depends on 1)

The method of claim 1, comprising:
preheating the third sheet of metal foil to a temperature falling within a range from 60° C. to 250° C.

### Claim 10 (depends on 1)

The method of claim 1,
wherein in the first stack, the second sheet of metal foil, the first prepreg, and the first sheet of metal foil are arranged in this order in a first direction,
the printed wiring board is made so that the printed wiring board warps to protrude in the first direction, and
the multilayer printed wiring board is manufactured so that the multilayer printed wiring board becomes flatter than the printed wiring board or warp to protrude in the opposite direction from the first direction.