FLEXIBLE PRINTED CIRCUIT BOARD

• US 20110030997A1
• Filed: 08/28/2009
• Published: 02/10/2011
• Est. Priority Date: 08/07/2009
• Status: Abandoned Application

• Current Assignee: Hon Hai Precision Industry Co., Ltd.
• Original Assignee: Hon Hai Precision Industry Co., Ltd.
• Inventors: HSU, SHOU-KUO
• Application Number:
  US12/549,376
• Publication Number:
  US 20110030997A1
• Time in Patent Office: Days
• US Class Current: 174/254
• CPC Class Codes: H05K 1/0245 Lay-out of balanced signal pairs, e.g. differential lines or twisted lines
• CPC Class Codes: H05K 1/0253 Impedance adaptations of transmission lines by special lay-out of power planes, e.g. providing openings H05K1/0251 takes precedence
• CPC Class Codes: H05K 1/16 incorporating printed electric components, e.g. printed resistor, capacitor, inductor
• CPC Class Codes: H05K 2201/09318 Core having one signal plane and one power plane
• CPC Class Codes: H05K 2201/09727 Varying width along a single conductor; Conductors or pads having different widths

Abstract

A flexible printed circuit board (FPCB) includes a differential pair arranged in a signal layer and a ground sheet arranged in a ground layer. The differential pair includes a number of section pairs, each of which includes two sections arranged in two transmission lines of the differential pair respectively. The ground sheet is opposite to a space between the two transmission lines of the differential pair. The differential pair is equivalent to a filter which includes several capacitors and several inductors. Each of the plurality of section pairs can achieve a desired characteristic impedance by adjusting a first distance between each section and the ground sheet, and a second distance between the two sections of each of the plurality of section pairs.

Claims

1. A flexible printed circuit board (FPCB) comprising:

a signal layer, wherein a differential pair comprising of two transmission lines is arranged in the signal layer; and

a ground layer adjacent to the signal layer, wherein a ground sheet made of conductive material is arranged in the ground layer;

the ground sheet is opposite to a space between the two transmission lines of the differential pair, and is parallel to the two transmission lines;

wherein

the differential pair comprises a plurality of section pairs, each of the plurality of section pairs comprises two sections arranged in the two transmission lines symmetrically, every two adjacent sections of each of the two transmission lines are different in width, each of the plurality of section pairs has a desired characteristic impedance relative to a predetermined first distance between each of the two sections of each of the plurality of section pairs and the ground sheet, and a predetermined second distance between the two sections of each of the plurality of section pairs.

2. The FPCB of claim 1, wherein the ground sheet is made of copper.

3. The FPCB of claim 1, wherein an insulating layer made of dielectric material is arranged between the signal layer and the ground layer.

4. The FPCB of claim 1, wherein every two adjacent section pairs are equivalent to a capacitor and an inductor of a low pass filter, each section of the section pairs which are equivalent to the capacitors has a greater width than each section of the section pairs which are equivalent to the inductors.

5. The FPCB of claim 4, wherein a length of each section of the section pairs which are equivalent to the capacitors is determined according to a first formula

6. A flexible printed circuit board comprising:

a signal layer, wherein a differential pair comprising of two transmission lines is arranged in the signal layer, the differential pair comprises a plurality of section pairs, each of the plurality of section pairs comprises two sections arranged in the two transmission lines respectively, the two sections of each of the plurality of section pairs have the same structures, every two adjacent section pairs are equivalent to a capacitor and an inductor respectively; and

a ground layer adjacent to the signal layer, wherein a ground sheet made of conductive material is arranged in the ground layer, a plurality of sections is defined in the ground sheet corresponding to the plurality of section pairs, each section of the ground sheet is opposite to a space between the two sections of the corresponding section pair;

wherein each of the plurality of section pairs has a desired characteristic impedance relative to a width of each section of the section pair, and a width of each of the plurality of sections of the ground sheet.

7. The flexible printed circuit board of claim 6, wherein a length of the ground sheet is equal to a length of each of the two transmission lines.