# US 10,307,989 B2 · Prepregs including UV curable resins useful for manufacturing semi-flexible PCBs

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- Number: US 10,307,989 B2
- Document ID: US10307989B2
- Status: Granted
- Kind: B2
- Application number: 15/693,001
- Filed: 2017-08-31
- Published: 2018-07-19
- Granted: 2019-06-04
- Earliest claimed: 2014-07-01
- Assignees: Isola USA Corp.
- Applicants: Isola USA Corp.
- Inventors: Roland Schönholz
- Web page: https://patentgrep.com/patent/US10307989B2

## CPC

- C08J 5/244: {using glass fibres}
- H05K 1/036: {Multilayers with layers of different types}
- B29C 35/0894: {provided with masks or diaphragms}
- B32B 5/024: {Woven fabric}
- B32B 5/26: another layer {next to it} also being fibrous or filamentary {(relative arrangement of fibres or filaments of different layers B32B5/12)}
- B32B 7/00: Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
- B32B 7/12: using interposed adhesives or interposed materials with bonding properties
- B32B 15/00: Layered products comprising {a layer of} metal
- B32B 15/04: comprising metal as the main or only constituent of a layer, {which is} next to another layer of {the same or of} a {different material (next to a bituminous or tarry layer B32B11/08; next to a water-setting substance layer B32B13/06; next to a glass layer B32B17/061; next to a cellulosic plastic layer B32B23/042)}
- B32B 15/08: of synthetic resin
- B32B 15/14: next to a fibrous or filamentary layer
- B32B 15/20: comprising aluminium or copper {(B32B15/016 and B32B15/017 take precedence)}
- B32B 27/00: Layered products comprising {a layer of} synthetic resin {(fibrous or filamentary layer made of a synthetic resin B32B5/02; particulate layer made of a synthetic resin B32B5/16; foamed layer made of a synthetic resin B32B5/18)}
- B32B 27/06: as the main or only constituent of a layer, {which is} next to another layer of {the same or of} a {different material (next to a layer of a particular substance B32B9/045; next to a bituminous or tarry layer B32B11/046; next to a water setting substance layer B32B13/12; next to a metal layer B32B15/08; next to a glass layer B32B17/10; next to a layer formed of natural mineral fibres or particles B32B19/045; next to a wood layer B32B21/08; next to a cellulosic plastic layer B32B23/08; next to a natural or synthetic rubber layer B32B25/08)}
- B32B 27/16: specially treated, e.g. irradiated
- B32B 27/18: characterised by the use of special additives
- B32B 27/26: using curing agents
- B32B 37/0076: {characterised in that the layers are not bonded on the totality of their surfaces}
- B32B 37/02: characterised by a sequence of laminating steps, e.g. by adding new layers at consecutive laminating stations
- B32B 37/26: with at least one layer which influences the bonding during the lamination process, e.g. release layers or pressure equalising layers
- H05K 3/4691: {Rigid-flexible multilayer circuits comprising rigid and flexible layers, e.g. having in the bending regions only flexible layers}
- B29C 2035/0827: {using UV radiation}
- 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 37/30: Partial laminating
- B32B 38/10: Removing layers, or parts of layers, mechanically or chemically
- B32B 2250/00: Layers arrangement
- B32B 2255/00: Coating on the layer surface
- B32B 2255/10: on synthetic resin layer or on natural or synthetic rubber layer
- B32B 2260/023: Two or more layers
- B32B 2260/046: Synthetic resin
- B32B 2262/101: Glass fibres
- B32B 2305/076: Prepregs
- B32B 2305/72: Cured, e.g. vulcanised, cross-linked
- B32B 2305/74: Partially cured
- B32B 2305/77: Uncured, e.g. green
- B32B 2307/20: having particular electrical or magnetic properties, e.g. piezoelectric
- B32B 2307/202: Conductive
- B32B 2307/30: having particular thermal properties
- B32B 2307/302: Conductive
- B32B 2307/40: having particular optical properties
- B32B 2307/41: Opaque
- B32B 2307/412: Transparent
- B32B 2310/0831: using UV radiation
- B32B 2457/00: Electrical equipment
- B32B 2457/08: PCBs, i.e. printed circuit boards
- C08J 2300/24: Thermosetting resins
- H05K 1/0278: {Rigid circuit boards or rigid supports of circuit boards locally made bendable, e.g. by removal or replacement of material}
- H05K 1/028: {Bending or folding regions of flexible printed circuits (H05K1/0283 takes precedence)}
- H05K 1/0373: {containing additives, e.g. fillers (H05K1/036 takes precedence)}
- H05K 1/118: {specially for flexible printed circuits, e.g. using folded portions}
- H05K 1/147: {at least one of the printed circuits being bent or folded, e.g. by using a flexible printed circuit (H05K1/148 takes precedence)}
- H05K 3/0044: {Mechanical working of the substrate, e.g. drilling or punching (H05K3/0008 takes precedence)}
- H05K 3/0064: {onto a polymeric substrate}
- H05K 3/429: {Plated through-holes specially for multilayer circuits, e.g. having connections to inner circuit layers}
- H05K 2201/0195: Dielectric or adhesive layers comprising a plurality of layers, e.g. in a multilayer structure
- H05K 2201/09063: Holes or slots in insulating substrate not used for electrical connections
- H05K 2201/09081: Tongue or tail integrated in planar structure, e.g. obtained by cutting from the planar structure
- H05K 2201/0909: Preformed cutting or breaking line
- H05K 2201/09127: PCB or component having an integral separable or breakable part
- H05K 2201/095: Conductive through-holes or vias
- H05K 2203/0228: Cutting, sawing, milling or shearing
- H05K 2203/056: Using an artwork, i.e. a photomask for exposing photosensitive layers
- Y10T 428/24314: Slit or elongated
- Y10T 428/24322: Composite web or sheet
- Y10T 428/24331: including nonapertured component
- Y10T 428/24612: Composite web or sheet
- Y10T 428/24802: Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]
- Y10T 428/24851: Intermediate layer is discontinuous or differential
- Y10T 428/2486: with outer strippable or release layer
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- 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)
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

Prepregs having a UV curable resin layer located adjacent to a thermally curable resin layer wherein the UV curable resin layer includes at least one UV cured resin portion and at least one UV uncured resin as well as methods for preparing flexible printed circuit boards using the prepregs.

## Claims

### Claim 1

A method of preparing a laminate sheet comprising the steps of:
(a) applying a mask to a first prepreg including a UV curable resin layer and a thermally curable resin layer wherein the mask is applied to the UV curable resin layer, the mask including at least one UV light transparent portion and at least one UV light opaque portion;
(b) directing UV light at the mask for a period of time sufficient to cure the UV curable resin layer underlying the UV light transparent portion of the mask to form a UV light treated first prepreg having at least one cured UV resin portion and at least one uncured UV resin portion;
(c) contacting a core layer with the UV light treated first prepreg such that the at least one cured UV resin portion and the at least one uncured UV resin portion contact the core layer to form a layup; and
(d) applying heat and/or pressure to the lay-up to form a laminated layup including a semi-flexible core having a rest material portion that overlies the at least one cured UV resin portion where the semi-flexible core layer is not substantially laminated to the at least one cured UV resin portion.

### Claim 2 (depends on 1)

The method of claim 1 wherein a second prepreg is laminated to the thermally curable resin layer of the first prepreg.

### Claim 3 (depends on 2)

The method of claim 2 wherein the second prepreg is laminated to the thermally curable resin layer of the first prepreg prior to method step (a).

### Claim 4 (depends on 2)

The method of claim 2 wherein the second prepreg is laminated to the thermally curable resin layer of the first prepreg following method step (b).

### Claim 5 (depends on 2)

The method of claim 2 wherein a layer of copper is placed between the second prepreg and the core layer.

### Claim 6 (depends on 1)

The method of claim 1 wherein the core layer includes a core having a first and a second planar surface and layer of copper on at least one of the first and second core planar surfaces.

### Claim 7 (depends on 6)

The method of claim 6 wherein the core layer includes a layer of copper on each of the first and second core planar surfaces.

### Claim 8 (depends on 1)

The method of claim 1 wherein the laminate rest material portion of the layup is removed to form a semi-flexible area.

### Claim 9 (depends on 1)

The method of claim 1 wherein the laminated layup includes a plated through hole.

### Claim 10 (depends on 1)

The method of claim 1 wherein the laminated layup is incorporated into a printed circuit board.

### Claim 11 (depends on 1)

The method of claim 1 wherein the UV curable resin layer has at least one UV light cured resin portion and at least on UV light uncured resin portion.

### Claim 12 (depends on 1)

The method of claim 1 wherein the thermally curable resin layer is b-staged.

### Claim 13 (depends on 1)

The method of claim 1 wherein the thermally curable resin layer is c-staged.

### Claim 14 (depends on 1)

The method of claim 1 wherein a layer of copper is placed between the first prepreg thermally curable resin layer and the core layer.