# US 11,309,238 B2 · Layout structure of a flexible circuit board

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- Number: US 11,309,238 B2
- Document ID: US11309238B2
- Status: Granted
- Kind: B2
- Application number: 17/227,470
- Filed: 2021-04-12
- Published: 2022-02-03
- Granted: 2022-04-19
- Earliest claimed: 2020-07-31
- Assignees: Chipbond Technology Corporation
- Applicants: Chipbond Technology Corporation
- Inventors: Yu-Chen Ma; Hsin-Hao Huang; Wen-Fu Chou; Gwo-Shyan Sheu
- Web page: https://patentgrep.com/patent/US11309238B2

## CPC

- H10W 70/688: {Flexible insulating substrates}
- 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 1/189: characterised by the use of flexible or folded printed circuits
- H10W 70/65: Shapes or dispositions of interconnections
- H05K 2201/068: wherein the coefficient of thermal expansion is important
- H05K 2201/09663: Divided layout, i.e. conductors divided in two or more parts
- H05K 2201/09727: Varying width along a single conductor; Conductors or pads having different widths
- H05K 2201/0989: Coating free areas, e.g. areas other than pads or lands free of solder resist
- H05K 2201/10674: Flip chip
- H05K 2201/10681: Tape Carrier Package [TCP]; Flexible sheet connector
- H10W 72/072: {of bump connectors}
- H10W 72/07232: {Compression bonding, e.g. thermocompression bonding}
- H10W 72/073: {of die-attach connectors}
- H10W 74/15: on active surfaces of flip-chip devices, e.g. underfills
- H10W 90/724: {between a chip and a stacked insulating package substrate, interposer or RDL}
- H10W 90/734: {between a chip and a stacked insulating package substrate, interposer or RDL}
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS

## Abstract

A layout structure of flexible circuit board includes a flexible substrate, a chip and a circuit layer. A chip mounting area and a circuit area are defined on a top surface of the flexible substrate, the circuit area surrounds the chip mounting area. The chip is mounted on the chip mounting area of the top surface and includes a bump. The circuit layer is disposed on the top surface. A connection portion of the circuit layer extends across a first side of the chip mounting area and into the chip mounting area. A transmission portion of the circuit layer is located on the circuit area and electrically connected to the connection portion. A stress release portion of the circuit layer is located between the transmission portion and a second side of the chip mounting area and is a comb-shaped structure.

## Claims

### Claim 1

A layout structure of flexible circuit board comprising:
a flexible substrate including a top surface, a chip mounting area and a circuit area are defined on the top surface, the circuit area surrounds the chip mounting area having a first side and a second side;
a chip mounted on the chip mounting area of the top surface and including a bump; and
a circuit layer disposed on the top surface and including a connection portion, a transmission portion and a stress release portion, the connection portion extends across the first side and into the chip mounting area and is electrically connected to the bump, the transmission portion is located on the circuit area and adjacent to the second side, a space of between 100 um and 800 um exists between the transmission portion and the second side of the chip mounting area, the stress release portion is located between the transmission portion and the second side of the chip mounting area and is a comb-shaped structure.

### Claim 2 (depends on 1)

The layout structure of flexible circuit board in accordance with claim 1, wherein a width of the transmission portion is greater than 50 um.

### Claim 3 (depends on 2)

The layout structure of flexible circuit board in accordance with claim 2, wherein the stress release portion includes a plurality of finger-like leads, a pitch between two adjacent of the plurality of finger-like leads is greater than 16 um.

### Claim 4 (depends on 3)

The layout structure of flexible circuit board in accordance with claim 3, wherein the circuit layer is not across the second side of the chip mounting area.

### Claim 5 (depends on 4)

The layout structure of flexible circuit board in accordance with claim 4, wherein a terminal of each of the plurality of finger-like leads is aligned with the second side of the chip mounting area.

### Claim 6 (depends on 3)

The layout structure of flexible circuit board in accordance with claim 3, wherein a length of each of the plurality of finger-like leads is between 100 um and 1000 um.

### Claim 7 (depends on 6)

The layout structure of flexible circuit board in accordance with claim 6, wherein a terminal of each of the plurality of finger-like leads is aligned with the second side of the chip mounting area, and the length of each of the plurality of finger-like leads is between 100 um and 800 um.

### Claim 8 (depends on 3)

The layout structure of flexible circuit board in accordance with claim 3, wherein each of the plurality of finger-like leads has a first width, an inner lead of the connection portion has a second width, the first width is greater than or equal to the second width, the second width is less than 15 um.

### Claim 9 (depends on 1)

The layout structure of flexible circuit board in accordance with claim 1, wherein the stress release portion includes a plurality of finger-like leads, a pitch between two adjacent of the plurality of finger-like leads is greater than 16 um.

### Claim 10 (depends on 9)

The layout structure of flexible circuit board in accordance with claim 9, wherein the circuit layer is not across the second side of the chip mounting area.

### Claim 11 (depends on 10)

The layout structure of flexible circuit board in accordance with claim 10, wherein a terminal of each of the plurality of finger-like leads is aligned with the second side of the chip mounting area.

### Claim 12 (depends on 9)

The layout structure of flexible circuit board in accordance with claim 9, wherein a length of each of the plurality of finger-like leads is between 100 um and 1000 um.

### Claim 13 (depends on 12)

The layout structure of flexible circuit board in accordance with claim 12, wherein a terminal of each of the plurality of finger-like leads is aligned with the second side of the chip mounting area, and the length of each of the plurality of finger-like leads is between 100 um and 800 um.

### Claim 14 (depends on 9)

The layout structure of flexible circuit board in accordance with claim 9, wherein each of the plurality of finger-like leads has a first width, an inner lead of the connection portion has a second width, the first width is greater than or equal to the second width, the second width is less than 15 um.

### Claim 15 (depends on 1)

The layout structure of flexible circuit board in accordance with claim 1, wherein the transmission portion is electrically connected to the connection portion and the stress release portion.

### Claim 16 (depends on 1)

The layout structure of flexible circuit board in accordance with claim 1, wherein the second side of the chip mounting area has a length of greater than or equal to 3 mm.