TWI394499B - Flexible printed circuitry - Google Patents

Description

Flexible circuit board

The present invention relates to a printed circuit board (PCB), and more particularly to a flexible printed circuit board (FPC).

There are many different types of printed circuit boards, some of which are rigid boards and some of which are flexible boards or soft boards. A flexible circuit board is a circuit board supported by a soft dielectric material. It can be used as a flexible cable or in a continuous dynamic bending product. It is currently used in the packaging and operation of liquid crystal display driver ICs. Electronic products are particularly broad, such as cell phones, notebook computers, and digital cameras.

In general, flexible circuit boards use Tape Automated Bonding (TAB) technology for wafer packaging. Commonly available tape and reel bonding technologies include Tape Carrier Package (TCP) and Chip-On-Film (COF) packages.

FIG. 1 is a cross-sectional view showing a conventional wafer disposed on a flexible circuit board. Referring to FIG. 1, the conventional flexible circuit board 1 has a package area 1a and a transmission area 1b on opposite sides of the package area 1a, wherein a wafer 2 is disposed on the flexible circuit board 1. The flexible circuit board 1 includes a flexible substrate 10, a patterned metal layer 12, and a protective layer 14.

In detail, the flexible substrate 10 has a plurality of transmission holes 10a located in the transmission region 1b. The patterned metal layer 12 is disposed on the flexible substrate 10, And the patterned metal layer 12 covers the flexible substrate 10 in the transmission zone 1b and exposes the transmission hole 10a. The encapsulation area 1a is covered with a protective layer 14, but the patterned metal layer 12 around the drive hole 10a is exposed.

2 is a schematic view of the wafer of FIG. 1 and a flexible circuit board being punched on a conveyor table. Referring to FIG. 1 and FIG. 2 simultaneously, the roller 16a and the roller 16b are disposed at both ends of the transmission path for winding the flexible circuit board 1. A plurality of gears 17 are disposed between the roller 16a and the roller 16b, and interfere with the transmission hole 10a of the flexible circuit board 1 to drive the flexible circuit board 1 forward. The punching cutter 3 is disposed on the transmission path to cut the flexible circuit board 1 on which the wafer 2 is packaged into a plurality of package units. However, since the patterned metal layer 12 around the transmission hole 10a is exposed, when the gear 17 and the transmission hole 10a interfere with each other, the transmission hole 10a is easily worn by friction to generate metal dust, thereby affecting the cleanliness of the process. Further, in the course of the transmission, there may be a case where the breaking strength of the transmission hole 10a of the flexible circuit board 1 is insufficient, and the breakage or the punching offset is liable to occur.

The invention provides a flexible circuit board which has good tensile strength and can improve the cleanliness of the process.

The present invention provides a flexible circuit board having a package area and a drive area on opposite sides of the package area. The flexible circuit board includes a flexible substrate, a patterned metal layer, and a dielectric layer. The flexible substrate has a plurality of drive holes located within the drive region. The patterned metal layer is disposed on the flexible substrate, and the patterned metal layer covers at least the flexible substrate in the transmission region and exposes the transmission hole. The dielectric layer covers the patterned metal in the transmission region Layer and expose the drive hole.

In an embodiment of the invention, the flexible circuit board further includes a protective layer. The protective layer is disposed in the package region, and the protective layer has a plurality of openings to define at least one die bond region and at least one outer pin bond region on the periphery of the die bond region in the package region. The patterned metal layer further includes a plurality of inner leads in the wafer bond region and a plurality of outer pins in the outer pin bond region.

In an embodiment of the invention, the dielectric layer and the protective layer are fabricated by the same process.

In an embodiment of the invention, the material of the dielectric layer comprises a polyimide resin, a polyester resin, an acrylic resin or an epoxy resin.

In an embodiment of the invention, the dielectric layer comprises a plurality of holes. These holes are disposed opposite the drive holes of the flexible substrate.

In an embodiment of the invention, the dielectric layer and the protective layer are made of the same material.

The flexible circuit board of the present invention covers the dielectric layer over the patterned metal layer in its transmission region. Compared with the prior art, the flexible circuit board of the present invention can provide better process cleanliness and good tensile strength, and can avoid the damage of the transmission hole during the transmission process of the flexible circuit board. A situation in which the flexible circuit board is broken or punched off.

The above and other objects, features, and advantages of the present invention will become more apparent from the understanding of the appended claims.

The following will be done with a flexible circuit board packaged in a film flip chip. The example is explained. However, as previously mentioned, the tape and tape type automatic bonding includes a tape and tape carrying package in addition to the film flip chip package. Therefore, the technical content disclosed in the following embodiments is not limited to the film flip chip package, and can also be applied to, for example, a tape carrier package or other possible occasions.

3 is a cross-sectional view showing a wafer disposed on a flexible circuit board according to an embodiment of the present invention, and FIG. 4 is a top view of the flexible circuit board of FIG. 3. It must be noted here that in order to clearly show the structure of the surface of the flexible circuit board, FIG. 4 omits the wafer of FIG. 3 and other possible components.

Referring to FIG. 3 and FIG. 4 simultaneously, in the embodiment, the flexible circuit board 100 has a package area 100a and a transmission area 100b on opposite sides of the package area 100a. The flexible circuit board 100 includes a flexible substrate 110, a patterned metal layer 120, and a dielectric layer 130.

In detail, the flexible substrate 110 has a plurality of transmission holes 112 located in the transmission region 100b, wherein the rollers can drive the flexible circuit board 100 to smoothly advance through the transmission holes 112. Most of the flexible substrate 110 is made of a soft insulating material, and the material thereof is, for example, a plastic substrate, a thinned glass substrate, a polyester substrate, a polyketone substrate, a polyether substrate, or a polyester. Substrate, polyolefin substrate, polyacetylene substrate, polyoxyalkylene substrate, polycycloolefin substrate, polycycloalkyl substrate, polyfluorene substrate, polyphenol substrate, poly An aldehyde substrate, or another polymer substrate, or a combination thereof.

The patterned metal layer 120 is disposed on the flexible substrate 110, and the patterned metal layer 120 covers at least the flexible substrate 110 in the transmission region 100b and exposes the transmission hole 112. In detail, the material of the patterned metal layer 120 overlying the flexible substrate 110 in the transmission region 100b is, for example, copper. Used to strengthen the structure of the transmission zone 100b.

In addition, the patterned metal layer 120 can also extend onto the flexible substrate 110 within the package region 100a to form patterned lines, including internal and external leads. In other words, the patterned metal layer 120 within the drive region 100b and the package region 100a can be fabricated simultaneously, for example, by the same copper foil layer as defined by photolithographic etching. Of course, in other embodiments, the patterned metal layer 120 in the transmission region 100b and the package region 100a may also be separately fabricated, and may have different materials or metal layers of different thicknesses to meet actual needs.

In addition, the dielectric layer 130 covers the patterned metal layer 120 in the transmission region 100b and exposes the transmission hole 112, wherein the dielectric layer 130 includes a plurality of holes 132. The hole 132 is disposed opposite to the transmission hole 112. In general, the dielectric layer 130 is used to insulate the patterned metal layer 120 from the outside air.

It is worth mentioning that, in this embodiment, the material of the dielectric layer 130 comprises a polyimide (PI) resin, a polyester (PET) resin, an acrylic resin or an epoxy ( Epoxy resin.

Referring to FIG. 3 again, in the embodiment, the wafer 200 is disposed on the flexible circuit board 100 in a flip-chip bonding manner to electrically connect the patterned metal layer 120 in the transmission region 100b by the bumps 160. The purpose of electronic signal transmission is achieved by the internal circuit of the flexible circuit board 100. In addition, encapsulant 150 covers wafer 200 and local flexible circuit board 100 and exposes the top surface of wafer 200.

In the present embodiment, since the flexible circuit board 100 covers the dielectric layer 130 on the patterned metal layer 120 in the transmission region 100b, it can The dust pollution during the transmission process of the flexible circuit board 100 is avoided, the process cleanliness is improved, and the tensile strength of the flexible circuit board 100 can be improved. In addition, it is also possible to avoid the occurrence of breakage or punching offset of the flexible circuit board 100 due to damage of the transmission hole 112 in the punching process.

Referring to FIG. 3 and FIG. 4 simultaneously, in the embodiment, the flexible circuit board 100 further includes a protective layer 140. The protective layer 140 is disposed in the package region 100a, and the protective layer 140 has a plurality of openings 142 to define at least one wafer bonding region 142a and at least one outer pin bonding region 142b located at the periphery of the wafer bonding region 142a in the packaging region 100a. . The patterned metal layer 120 further includes a plurality of inner leads 122 located within the wafer bond region 142a and a plurality of outer leads 124 located within the outer lead bonding (OLB) region 142b.

It is worth mentioning that only one wafer bonding region 142a and two outer pin bonding regions 142b are illustrated in FIG. 4, and the outer pin bonding regions 142b are located on the upper and lower sides of the wafer bonding region 142a. In general, the flexible circuit board 100 can be used to cut the drive region 100b by machining, leaving only the die bond region 142a and the outer pin bond region 142b to be applied, for example, by using an outer portion of the outer lead 124 by an alien The conductive adhesive is electrically connected to the display panel, and the other portion of the lead 124 is electrically connected to the circuit board by the anisotropic conductive adhesive.

In particular, in the present embodiment, the dielectric layer 130 in the transmission region 100b and the protective layer 140 in the package region 100a may be the same film layer and have the same material. That is, it is produced through the same process, such as film attachment or printing of a dielectric material. However, in other embodiments, the dielectric layer 130 and the protective layer 140 may also be separately fabricated, and may have different materials or different structural compositions, for example, composed of different numbers of multiple layers. Provide different tensile strength and protection.

Specifically, the dielectric layer 130 on the patterned metal layer 120 in the transmission region 100b serves to strengthen the structure of the transmission region 100b to increase the tensile strength of the transmission hole 112 and its surroundings; and the pattern located in the package region 100a. The protective layer 140 on the metal layer 120 serves to protect the patterned metal layer 120 within the package region 100a.

In summary, the flexible circuit board of the present invention has at least the following features and advantages: (1) By covering the dielectric layer on the patterned metal layer in the transmission region, the flexible circuit board can be prevented from being driven. Possible dust pollution to improve process cleanliness.

(2) By covering the dielectric layer on the patterned metal layer in the transmission region, the tensile strength of the transmission hole and its surroundings can be increased, thereby improving the process reliability. For example, it is possible to avoid a situation in which the flexible circuit board is broken or the punching is shifted due to damage when the flexible circuit board is punched.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

1, 100‧‧‧Flexible circuit boards

1a, 100a‧‧‧ package area

1b, 100b‧‧‧ transmission zone

2, 200‧‧‧ wafer

10, 110‧‧‧Flexible substrate

10a, 112‧‧‧ drive holes

12, 120‧‧‧ patterned metal layer

14, 140‧‧ ‧ protective layer

16a, 16b‧‧‧Rollers

122‧‧‧ inner pin

124‧‧‧External pin

130‧‧‧Dielectric layer

132‧‧‧ hole

140‧‧‧Protective layer

142‧‧‧ openings

142a‧‧‧ wafer junction area

142b‧‧‧Outer pin junction

150‧‧‧Package colloid

160‧‧‧Bumps

FIG. 1 is a schematic cross-sectional view showing a conventional wafer disposed on a flexible circuit board.

2 is a schematic view of the wafer of FIG. 1 and a flexible circuit board being punched on a conveyor table.

3 is a cross-sectional view showing a wafer disposed on a flexible circuit board according to an embodiment of the present invention.

4 is a top plan view of the flexible circuit board of FIG. 3.

100‧‧‧Flexible circuit board

100a‧‧‧Packing area

100b‧‧‧ Transmission zone

110‧‧‧Flexible substrate

112‧‧‧Drive hole

120‧‧‧ patterned metal layer

130‧‧‧Dielectric layer

132‧‧‧ hole

140‧‧‧Protective layer

142‧‧‧ openings

150‧‧‧Package colloid

160‧‧‧Bumps

200‧‧‧ wafer

Claims (6)

A flexible circuit board having a package area and a transmission area on opposite sides of the package area, the flexible circuit board comprising: a flexible substrate having a plurality of transmission holes in the transmission area a patterned metal layer disposed on the flexible substrate, and the patterned metal layer covers at least the flexible substrate in the transmission region and exposes the transmission holes; and a dielectric layer Covering the patterned metal layer in the transmission region and exposing the transmission holes. The flexible circuit board of claim 1, further comprising a protective layer disposed in the package region, the protective layer having a plurality of openings to define at least one wafer bond in the package region The region and the at least one outer pin bond region on the periphery of the die bond region further includes a plurality of inner leads in the die bond region and a plurality of outer pins in the outer pin bond region. The flexible circuit board of claim 2, wherein the dielectric layer and the protective layer are fabricated by the same process. The flexible circuit board of claim 1, wherein the material of the dielectric layer comprises a polyimide resin, a polyester resin, an acrylic resin or an epoxy resin. The flexible circuit board of claim 1, wherein the dielectric layer comprises a plurality of holes, and the holes are disposed opposite to the transmission holes. The flexible circuit board of claim 2, wherein the dielectric layer is made of the same material as the protective layer.