TWI536879B - Flexible printed circuit board and a manufacture method thereof - Google Patents

Description

Flexible circuit board and manufacturing method thereof

The present invention relates to a flexible circuit board and a method of fabricating the same.

Flexible Printed Circuit Board (FPCB) is widely used in various electronic products. It plays an important role in mounting and supporting electronic components. It is an indispensable component in electronic products. The flexible circuit board has the characteristics of flexibility, and the high reliability is put forward. In the prior art, the flexible circuit board has a lead wire extending from the solder pad in addition to the solder pad connected to the electronic component, and the lead wire is often It will occupy a large space, making the wiring area of the flexible circuit board too large, which is not conducive to thinning.

The invention provides a flexible circuit board comprising a substrate and a soldering pad, the substrate comprising a first surface and a second surface, the first surface extending in a direction of the substrate, The second surface is parallel to the first surface, the first surface is provided with a solder pad, the second surface is provided with a circuit pattern, and the substrate is provided with an opening for connecting the first surface and the second surface a hole in which an electrical conductor is disposed to electrically connect the pad and the circuit pattern, and the second surface is provided with a protective film. The method for manufacturing a flexible circuit board includes: providing a double-sided copper-clad substrate, opening an opening in the substrate, and providing a pad on the opening on the first surface Providing a circuit pattern on the second surface; and coating a protective film on the second surface.

Compared with the prior art, the present invention provides a flexible circuit board and a manufacturing method thereof, which improve the available wiring area of a flexible circuit board by providing openings in the substrate.

1‧‧‧Soft circuit board

10‧‧‧Substrate

101‧‧‧ first surface

102‧‧‧ second surface

11‧‧‧ solder pads

12‧‧‧ circuit graphics

121‧‧‧Metal wire

121a‧‧‧Metal wire part 1

121b‧‧‧Metal wire part II

121c‧‧‧Metal wire part III

121d‧‧‧Metal wire part IV

13‧‧‧Opening

14‧‧‧Electric conductor

15‧‧‧Insulator

21‧‧‧Protective film

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view showing a first embodiment of a flexible circuit board of the present invention.

2 is a top plan view of the flexible circuit board of FIG. 1.

Figure 3 is a schematic cross-sectional view taken along line III-III of Figure 1.

4 is a schematic view showing the second surface of the substrate of FIG. 3 covered with a protective film according to the first embodiment of the present invention.

Figure 5 is a cross-sectional view showing a second embodiment of the flexible circuit board of the present invention.

Figure 6 is a cross-sectional view showing a third embodiment of the flexible circuit board of the present invention.

As shown in FIG. 1, FIG. 2 and FIG. 3, a first embodiment of the present invention provides a flexible circuit board 1. The flexible circuit board 1 includes a substrate 10, a pad 11, a circuit pattern 12, an opening 13, an electrical conductor 14, and a protective film 21.

The substrate 10 includes a first surface 101 and a second surface 102. The second surface 102 and the first surface 101 are two surfaces that are opposite in parallel. The substrate 10 is made of a flexible organic material such as polyimide.

The first surface 101 of the substrate 10 is provided with a plurality of pads 11 near the ends. The pad 11 can be obtained by etching a copper foil layer covered on the first surface 101 of the substrate 10, The pad 11 is used to connect electronic devices.

As shown in FIG. 2, the circuit pattern 12 is formed on the second surface 102 of the substrate 10. The circuit pattern 12 includes a plurality of metal wires 121. The metal wire 121 includes a metal wire first portion 121a, a metal wire second portion 121b, a metal wire third portion 121c, and a metal wire fourth portion 121d. One ends of the metal wire second portion 121b and the metal wire third portion 121c are respectively connected to opposite sides of the conductor 14, and the other ends of the metal wire second portion 121b and the metal wire third portion 121c are respectively connected to the metal wire first portion 121a and the metal The fourth portion of the wire is 121d. The metal wire first portion 121a is substantially parallel to the metal wire fourth portion 121d.

The metal wire second portion 121b has an angle with the metal wire first portion 121a. The metal wire fourth portion 121d has a certain angle with the metal wire third portion 121c. The plurality of metal wire first portions 121a are spaced apart from each other in parallel. The plurality of metal wire second portions 121b are parallel to each other in parallel. The plurality of metal wire third portions 121c are spaced apart in parallel. The plurality of metal wire fourth portions 121d are spaced apart in parallel. The size of the included angle range and the arrangement of the plurality of metal wires 121 are based on the convenient wiring of the flexible circuit board 1.

As shown in FIG. 1, the openings 13 of the present embodiment have a plurality of openings 13 and are all formed on the substrate 10. Each of the openings 13 is configured to communicate with the pad 11 disposed on the first surface 101 of the substrate 10 and the circuit pattern 12 disposed on the second surface 102 of the substrate 10. In this embodiment, the arrangement of the plurality of openings 13 is obliquely linear from top to bottom, that is, the line connecting the plurality of openings 13 is straight or curved, and is formed at the edge of the end of the substrate 10. A certain angle.

Figure 3 is a schematic cross-sectional view taken along line III-III of Figure 1. As shown in FIG. 3 , in the embodiment, the opening 13 is a through hole, and the through hole 13 penetrates the substrate 10 and the bonding pad 11 substantially in a direction perpendicular to the first surface 101 and the second surface 102 . And circuit pattern 12. The conductor 14 is substantially in the shape of a hollow column. In the embodiment, the conductor 14 is embedded in the cylindrical surface of the inner wall of the through hole and extends at the edge of the second surface 102 of the substrate 10 . The opposite ends of the conductor 14 are electrically connected to the pad 11 on the first surface 101 and the circuit pattern 12 on the second surface 102, respectively, thereby achieving signal transmission between the pad 11 and the circuit pattern 12. In this embodiment, the material of the electrical conductor 14 may be a copper foil.

As shown in FIG. 4, in the alternative embodiment, the circuit pattern 12 may be covered with a protective film 21 to prevent the circuit pattern 12 from being exposed to air and being oxidized. The protective film 21 may be a protective lacquer or a three-proof adhesive.

As shown in FIG. 5, the flexible circuit board provided by the second embodiment of the present invention has substantially the same structure as the flexible circuit board 1 of the first embodiment, and the difference is that the hollow metal conductor 14 is filled with an insulator. 15. The insulator 15 is used to prevent the electronic device from falling off the pad 11 due to moisture entering the opening 13 when the pad 11 is connected to the electronic device. In this embodiment, the insulator 15 may be a solder resist ink.

As shown in FIG. 6, the flexible circuit board provided by the third embodiment of the present invention is substantially the same as the structural board of the flexible circuit 1 of the first embodiment. The difference is that the opening 13 is a blind hole. The blind holes penetrate the circuit pattern 12 on the substrate 10 and the second surface 102 in a direction perpendicular to the first surface 101 and the second surface 102, but do not penetrate the pad 11. Through such a design, it is possible to prevent the electronic device from falling out of the bonding pad 11 due to moisture entering the opening 13 from the direction of the bonding pad 11 when the bonding pad 11 is connected to the electronic device, thereby effectively improving the reliability of the product.

The flexible circuit board wiring provided by the embodiment of the invention occupies a small area of the substrate, and at the same time effectively prevents the solder pad 11 from being connected to the electronic device, and the water vapor enters the opening 13 to cause the electronic device to fall off from the bonding pad 11 to improve the product. reliability.

The invention also provides a method for manufacturing a flexible circuit board, comprising the following steps:

In step S101, a double-sided copper-clad substrate 10 is provided, and an opening 13 is formed in the substrate 10, and a pad 11 is disposed on the opening 13 of the first surface 101 of the substrate 10, The pad 11 can be formed by etching or the like.

In step S102, the circuit pattern 12 is formed on the second surface 102 of the substrate 10 by etching or the like. The electrical conductor 14 is formed by chemical deposition on the cylindrical surface of the inner wall of the opening 13 , and the electrical conductor 14 extends partially around the opening 13 of the second surface 102 of the substrate 10 .

In step S103, a protective film 21 is coated on the second surface 102 of the substrate 10. The protective film 21 may be a protective lacquer or a three-proof adhesive.

Compared with the prior art, the flexible circuit board manufacturing method provided by the embodiment of the present invention does not need to provide a reinforcing plate and dispensing, which reduces the cost of materials and shortens the production process.

It can be understood that the number and arrangement of the through holes in the pad 11 of the flexible circuit board 1 provided by the present invention are not limited thereto, and the description of each of the pads 11 corresponding to the opening 13 is only It is convenient to understand that any of the openings 13 for connecting the pads 11 provided on the first surface 101 of the substrate 10 and the circuit patterns 12 provided on the second surface 102 of the substrate 10 are within the scope of the present invention. In addition, the number and arrangement of the metal wires 121 in the present invention may also be different, but may be adjusted according to the specific design.

The above embodiments are only used to illustrate the technical solutions of the present invention, and the present invention is not limited thereto. The present invention will be described in detail with reference to the preferred embodiments, and those skilled in the art should understand that the technical solutions of the present invention may be modified or substituted. Without leaving The spirit and scope of the technical solution of the present invention.

10‧‧‧Substrate

101‧‧‧ first surface

102‧‧‧ second surface

11‧‧‧ solder pads

121‧‧‧Metal wire

13‧‧‧Opening

14‧‧‧Electric conductor

21‧‧‧Protective film

Claims (10)

A flexible circuit board comprising a substrate and a bonding pad, the substrate comprising a first surface and a second surface opposite to the first surface, the first surface being provided with a plurality of pads adjacent to the end, the improvement The second surface of the substrate is provided with a circuit pattern, and the substrate is provided with an opening for connecting each of the pads to the first surface and the second surface, and the opening is provided with an electrical connection An electric conductor of a pad and a circuit pattern, the conductor being embedded in a cylindrical surface of the inner wall of the opening. The flexible circuit board of claim 1, wherein the connection of the plurality of openings has a certain angle with the edge of the end of the substrate. The flexible circuit board of claim 1, wherein the circuit pattern comprises a plurality of metal wires, the metal wire comprising a first portion of the metal wire, the second portion of the metal wire, the third portion of the metal wire, and the metal wire The fourth part, the second part of the metal wire and the third part of the metal wire are respectively connected to opposite sides of the conductor, the second part of the metal wire and the other end of the third part of the metal wire are respectively connected with the first part of the metal wire and the fourth part of the metal wire section. The first portion of the metal wire is substantially parallel to the fourth portion of the metal wire, the second portion of the metal wire has an angle with the first portion of the metal wire, and the fourth portion of the metal wire has a certain angle with the third portion of the metal wire. The flexible circuit board of claim 1, wherein the opening is a through hole, and the through hole penetrates the substrate in a direction perpendicular to the first surface and the second surface, and is disposed on the first surface a solder pad on the upper surface and a circuit pattern disposed on the second surface. The flexible circuit board of claim 1, wherein the electrical conductor is embedded in the opening and extends partially around the second surface opening of the substrate. The flexible circuit board of claim 4, wherein the conductive inner wall is filled with an insulator . The flexible circuit board of claim 1, wherein the opening is a blind hole, and the blind hole penetrates the substrate and the second surface in a direction perpendicular to the first surface and the second surface In the circuit pattern, the opening does not penetrate the corresponding pad. A method for manufacturing a flexible circuit board, comprising: providing a double-sided copper-clad substrate, wherein the substrate is provided with an opening, and the opening on the first surface of the substrate is provided with a solder a pad; forming a circuit pattern on the second surface of the substrate, the cylindrical inner surface of the opening is provided with an electrical conductor electrically connecting the pad and the circuit pattern; and the second surface of the substrate is coated with Protective film. The method of manufacturing a flexible circuit board according to claim 8, wherein the solder pad is formed by etching a copper covering the first surface of the substrate. The method of manufacturing a flexible circuit board according to claim 8, wherein the conductor is formed by a method of chemical deposition.