# US 10,321,560 B2 · Dummy core plus plating resist restrict resin process and structure

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- Number: US 10,321,560 B2
- Document ID: US10321560B2
- Status: Granted
- Kind: B2
- Application number: 14/995,087
- Filed: 2016-01-13
- Published: 2017-05-18
- Granted: 2019-06-11
- Earliest claimed: 2015-11-12
- Assignees: Multek Technologies Limited
- Applicants: Multek Technologies Limited
- Inventors: Pui Yin Yu; Mark Zhang; Jiawen Chen
- Web page: https://patentgrep.com/patent/US10321560B2

## CPC

- H05K 1/0278: {Rigid circuit boards or rigid supports of circuit boards locally made bendable, e.g. by removal or replacement of material}
- H05K 1/0298: {Multilayer circuits}
- H05K 1/115: {Via connections; Lands around holes or via connections (H05K1/112 takes precedence)}
- H05K 3/067: {Etchants}
- H05K 3/181: {by electroless plating (adhesives therefor H05K3/387)}
- H05K 3/4611: {by laminating two or more circuit boards (H05K3/4652 takes precedence)}
- H05K 3/4691: {Rigid-flexible multilayer circuits comprising rigid and flexible layers, e.g. having in the bending regions only flexible layers}
- H05K 1/0393: {Flexible materials (H05K1/038 takes precedence; specific organic compositions are classified in H05K1/0313 and subgroups)}
- H05K 1/118: {specially for flexible printed circuits, e.g. using folded portions}
- H05K 2203/0228: Cutting, sawing, milling or shearing
- H05K 2203/0574: Stacked resist layers used for different processes
- H05K 2203/06: Lamination
- H05K 2203/308: Sacrificial means, e.g. for temporarily filling a space for making a via or a cavity or for making rigid-flexible PCBs
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS

## Abstract

A printed circuit board (PCB) has multiple layers, where select portions of inner layer circuitry, referred to as inner core circuitry, are exposed from the remaining layers. The PCB having an exposed inner core circuitry is formed using a dummy core plus plating resist process. The select inner core circuitry is part of an inner core. The inner core corresponding to the exposed inner core circuitry forms a semi-flexible PCB portion. The semi-flexible PCB portion is an extension of the remaining adjacent multiple layer PCB. The remaining portion of the multiple layer PCB is rigid. The inner core is common to both the semi-flexible PCB portion and the remaining rigid PCB portion.

## Claims

### Claim 1

A printed circuit board comprising:
a. a rigid printed circuit board portion comprising a laminated stack of a plurality of non-conducting layers and a plurality of conductive layers, wherein the laminated stack further comprises a first portion of an inner core structure; and
b. a semi-flexible printed circuit board portion comprising a second portion of the inner core structure and exposed plating resist, wherein the inner core structure is a continuous structure that extends through both the rigid printed circuit board portion and the semi-flexible printed circuit board portion, further wherein the second portion of the inner core structure comprises exposed inner core circuitry, wherein the plating resist is limited to the semi-flexible printed circuit board portion of the printed circuit board and is limited to contacting a side wall of the rigid circuit board portion corresponding to a non-conducting layer of the rigid printed circuit board portion and the second portion of the inner core structure immediately adjacent the side wall of the rigid circuit board portion, further wherein the inner core structure comprises an inner core non-conductive layer having a first surface and a second surface opposite the first surface, and the first surface and the second surface of the inner core non-conductive layer form a continuous planar surface across the entire semi-flexible printed circuit board portion.

### Claim 2 (depends on 1)

The printed circuit board of claim 1 wherein each of the conductive layers is pattern etched.

### Claim 3 (depends on 1)

The printed circuit board of claim 1 further comprising one or more plated through hole vias in the rigid printed circuit board portion.

### Claim 4 (depends on 1)

The printed circuit board of claim 1 wherein the rigid printed circuit board portion comprises a first rigid printed circuit board portion, further wherein the printed circuit board further comprises a second rigid printed circuit board portion comprising a second laminated stack of a plurality of non-conducting layers and a plurality of conductive layers, wherein the second laminated stack further comprises a third portion of an inner core structure.

### Claim 5 (depends on 1)

The printed circuit board of claim 1 wherein the inner core structure further comprises a first conductive layer positioned on the first surface of the inner core non-conductive layer.

### Claim 6 (depends on 5)

The printed circuit board of claim 5 wherein the first conductive layer of the inner core structure comprises the inner core circuitry in the second portion of the inner core structure.

### Claim 7 (depends on 6)

The printed circuit board of claim 6 wherein the inner core structure further comprises a second conductive layer positioned on the second surface of the inner core non-conductive layer.

### Claim 8 (depends on 7)

The printed circuit board of claim 7 wherein the second conductive layer of the inner core structure comprises the inner core circuitry in the second portion of the inner core structure, wherein the plating resist is coupled to both the first surface and the second surface of the inner core non-conductive layer within the second portion of the inner core structure.