CN105578718B - Flexible PCB, circuit connection structure and mobile terminal - Google Patents

Abstract

The invention discloses a kind of flexible PCBs, including the first cover layer being cascading, first line layer, transparent flexible substrate, second line layer and the second cover layer, the transparent flexible substrate includes line areas and bonding pad, the position hollow out of bonding pad described in the first cover layer face, the first line layer includes the pad positioned at the circuit of the line areas and positioned at the bonding pad, the circuit and pad electrical connection, the position hollow out of bonding pad described in the second line layer face, the location transparency of bonding pad described in the second cover layer face is arranged.Flexible PCB welding contraposition easy to implement of the present invention.The invention also discloses a kind of circuit connection structures and a kind of mobile terminal.

Description

Flexible circuit board, circuit connection structure and mobile terminal

technical field

The invention relates to the technical field of circuit connection, in particular to a flexible circuit board, a circuit connection structure and a mobile terminal.

Background technique

With the rapid development of electronic technology, various electronic products according to the different needs of consumers are constantly being introduced. The consumer market makes all kinds of personalized electronic products sell well, among which portable electronic devices, such as mobile phones, PDAs (personal digital assistants), digital cameras, liquid crystal modules and other products are more mainstream. Moreover, the above-mentioned design trends of electronic products use light weight, thin profile, low price, high quality, and high precision as the main incentives to stimulate consumers to buy.

In addition, in order to make their own functions more powerful and further attract consumers' desire to buy, general electronic products will combine more modules to add various functions. Therefore, in addition to adding displays, main circuit boards, and memory, A camera module or a network operation module is also added to make the functions of its electronic products more diversified.

The above-mentioned different modules often need to be connected by wires, so cables or flexible circuit boards are usually used for wire connection, and these modules are connected by welding. However, as modern electronic products are becoming lighter, thinner and shorter, the welding structure tends to be finer. Therefore, in order to realize the installation of high-density circuits in a relatively narrow product volume, the solder pads formed on the circuit board not only have a finer size, but also have a denser arrangement.

It should be noted that when the pads on the circuit board tend to be arranged at a high density, during the soldering process, the soldering dislocation of the pads often occurs due to the small spacing, resulting in a short circuit between the pads. This kind of short circuit problem caused by pad welding dislocation has become the main factor for the increase of the defect rate of the circuit board.

Contents of the invention

The technical problem to be solved by the present invention is to provide a flexible circuit board that can easily and accurately align pads, a circuit connection structure using the flexible circuit board, and a mobile terminal using the flexible circuit board.

In order to achieve the above object, the embodiment of the present invention adopts the following technical solutions:

In one aspect, a flexible circuit board is provided, comprising a first cover film layer, a first circuit layer, a transparent flexible substrate, a second circuit layer and a second cover film layer stacked in sequence, the transparent flexible substrate includes a circuit area and The connection area, the position of the first cover film layer facing the connection area is hollowed out, the first circuit layer includes a line in the line area and a pad in the connection area, the line and the The pads are electrically connected, the second circuit layer is hollowed out at the position facing the connection area, and the second covering film layer is transparently provided at the position facing the connection area.

Preferably, the second covering film layer is hollowed out at the position facing the connection area.

Preferably, a junction line is formed at the junction of the circuit area and the connection area of the transparent flexible substrate, a first distance is formed between the second cover film layer and the junction line, and the second circuit layer A second distance is formed with the boundary line, and the second distance is greater than the first distance.

Preferably, the first cover film layer and the second cover film layer are transparent film layers.

Preferably, the second covering film layer is made of a transparent material and covers the connection area of the flexible circuit board.

Preferably, a junction line is formed at the junction of the wiring area and the connection area of the transparent flexible substrate, and a second distance is formed between the second wiring layer and the junction line.

Preferably, the first covering film layer is a transparent film layer.

Preferably, the material of the transparent flexible substrate is polyimide.

On the other hand, there is also provided a circuit connection structure, comprising the flexible circuit board as described in any one of the above, a transparent anisotropic conductive adhesive film and a device with a connection pad, the pad and the connection pad The pads are provided in one-to-one correspondence, and the anisotropic conductive adhesive film is placed between the pads and the connection pads to realize electrical connection.

Preferably, the soldering area of the pad is smaller than the soldering area of the connecting pad.

In yet another aspect, a mobile terminal is also provided, including the flexible circuit board as described in any one of the above items.

Compared with the prior art, the present invention has the following beneficial effects:

According to the flexible circuit board of the present invention, because the position of the first covering film layer facing the connection area is hollowed out, the flexible substrate is a transparent substrate, and the position of the second circuit layer facing the connection area is hollowed out, the The second cover film layer is transparently disposed at the position facing the connection area, so the periphery of the pad in the connection area of the flexible circuit board is in a transparent state. When the flexible circuit board is connected to the connection pads of other devices, it can be seen intuitively whether the pads are in one-to-one correspondence with the connection pads, which is simple and intuitive, high in efficiency, and improves welding yield.

When the circuit connection structure of the present invention is connected, first place the connection pad of the device facing up, place the anisotropic conductive adhesive film on the connection pad, and then place the The welding pad of the flexible circuit board faces down and is aligned and overlapped with the connecting pad. Since the periphery of the pad of the flexible circuit board is in a transparent state and the anisotropic conductive adhesive film is transparent, when the pad of the flexible circuit board is aligned with the connection pad of the device, It can be seen intuitively whether the pads and the connection pads are aligned and placed one by one, which is simple and intuitive, high in efficiency, and improves the welding yield.

Description of drawings

In order to illustrate the technical solution of the present invention more clearly, the accompanying drawings used in the implementation will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some implementations of the present invention. As far as technical personnel are concerned, other drawings can also be obtained like these drawings without paying creative work.

FIG. 1 is a schematic cross-sectional structure diagram of a flexible circuit board provided by an embodiment of the present invention.

FIG. 2 is a schematic top view of a flexible circuit board provided by an embodiment of the present invention.

FIG. 3 is a schematic cross-sectional structure diagram of another flexible circuit board provided by an embodiment of the present invention.

FIG. 4 is a schematic cross-sectional structure diagram of a circuit connection structure provided by an embodiment of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention.

Please refer to FIG. 1 and FIG. 2 . FIG. 1 is a schematic cross-sectional structure diagram of a flexible circuit board provided by an embodiment of the present invention, and FIG. 2 is a schematic top view of a flexible circuit board provided by an embodiment of the present invention. The flexible circuit board described in the embodiment of the present invention includes a first cover film layer 1, a first circuit layer 2, a transparent flexible substrate 3, a second circuit layer 4 and a second cover film layer 5 which are sequentially stacked. The substrate 3 includes a circuit area 100 and a connection area 200, the first cover film layer 1 is hollowed out at the position facing the connection area 200, and the first circuit layer 2 includes electrically connected lines located in the line area 100 and The pad 21 located in the connection area 200 is hollowed out at the position where the second circuit layer 4 is facing the connection area 200 , and the second covering film layer 5 is transparently disposed at a position where the connection area is facing.

In this embodiment, since the position of the first cover film layer 1 of the flexible circuit board facing the connection area 200 is hollowed out, the flexible substrate 3 is a transparent substrate, and the second circuit layer 4 is facing The position of the connection area 200 is hollowed out, and the second cover film layer 5 is set transparently to the position of the connection area, so the periphery of the pad 21 in the connection area 200 of the flexible circuit board is in the transparent state. When the flexible circuit board is connected to the connection pads of other devices, it can be seen intuitively whether the pads 21 are in one-to-one correspondence with the connection pads, which is simple and intuitive, with high efficiency and improved Welding yield.

As a preferred embodiment of the present invention, as shown in FIG. 1 , the position of the second cover film 5 facing the connection area 200 is hollowed out, so the second cover film 5 is facing the connection area 200 The position of is transparent and visible.

Further, a junction line A is formed at the junction of the circuit area 100 and the connection area 200 of the transparent flexible substrate 3, and a first distance S1 is formed between the second cover film layer 5 and the junction line A, so The second circuit layer 4 and the boundary line A form a second distance S2, and the second distance S2 is greater than the first distance S1. That is to say, the second circuit layer 4 forms a certain distance from the connection area 200 to protect the circuits in the circuit layer 4 from being damaged during the connection and soldering of the flexible circuit board, and at the same time, the second cover film layer 5 The second circuit layer 4 is completely covered for protection.

Further, the first cover film layer 1 and the second cover film layer 5 can be made of transparent material, so as to realize the full visibility of the circuit of the flexible circuit board. Of course, the first cover film layer 1 and the second cover film layer 5 can also be opaque, which can be set according to specific requirements.

Further, the transparent flexible substrate 3 is made of polyimide.

As another preferred embodiment of the present invention, please refer to FIG. 3 , the second cover film layer 5 is made of a transparent material and covers the connection area 200 of the flexible circuit board, so the second cover film 5 is The position of the connection area 200 is transparently visible.

Further, a junction line A is formed at the junction of the circuit area 100 and the connection area 200 of the transparent flexible substrate 3, and a second distance S2 is formed between the second circuit layer 4 and the junction line A, that is, A certain distance is formed between the second circuit layer 4 and the connection area 200 to protect the circuits in the circuit layer 4 from being damaged during the connection and soldering of the flexible circuit board.

Further, the first covering film layer 1 can be made of transparent material, so as to realize the full visibility of the circuit of the flexible circuit board. Of course, the first cover film layer 1 can also be opaque, which can be set according to specific requirements.

Further, the transparent flexible substrate 3 is made of polyimide.

Please refer to Fig. 4, the embodiment of the present invention also provides a circuit connection structure, including the flexible circuit board as described in the previous embodiment, the transparent anisotropic conductive adhesive film 7 and the device 6 with the connection pad 61, the The pads 21 and the connection pads 61 are provided in one-to-one correspondence, and the anisotropic conductive adhesive film 7 is placed between the pads 21 and the connection pads 61 to realize electrical connection.

When the circuit connection structure is connected, first place the connection pad 61 of the device 6 facing up, place the anisotropic conductive adhesive film 7 on the connection pad 61, and then place the anisotropic conductive adhesive film 7 on the connection pad 61. The bonding pads 21 of the flexible circuit board are aligned and overlapped with the connecting pads 61 facing downward. Since the periphery of the pad 61 of the flexible circuit board is in a transparent state and the anisotropic conductive adhesive film 7 is transparent, the pad 21 of the flexible circuit board is aligned with the connection of the device 6 When the pads 61 are connected, it can be seen intuitively whether the pads 21 and the connection pads 61 are aligned and placed one by one, which is simple and intuitive, high in efficiency, and improves the welding yield.

Furthermore, the soldering area of the pad is smaller than the soldering area of the connection pad, which further reduces the risk of dislocation when the pad 21 is aligned with the connection pad 61 and improves the soldering yield.

An embodiment of the present invention also provides a mobile terminal, including the above-mentioned flexible circuit board. The mobile terminal refers to computer equipment that can be used on the move, including but not limited to mobile phones, notebooks, tablet computers, POS machines, vehicle-mounted computers, cameras, etc.

The above description is a preferred embodiment of the present invention, and it should be pointed out that for those skilled in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications are also considered Be the protection scope of the present invention.

Claims (10)

1. A flexible circuit board, characterized in that it includes a first cover film layer, a first circuit layer, a transparent flexible substrate, a second circuit layer and a second cover film layer that are stacked in sequence, and the transparent flexible substrate includes a circuit region and a connection region, the first cover film layer is hollowed out at the position facing the connection region, the first circuit layer includes a circuit located in the circuit region and a pad located in the connection region, the circuit and The pads are electrically connected, the second circuit layer is hollowed out at the position facing the connection area, the second covering film layer is transparently provided at the position facing the connection area, and the periphery of the pad is in a transparent state, During the process of connecting the flexible circuit board to the device having the connection pads, the alignment between the pads and the connection pads is visually visible. 2 . The flexible circuit board according to claim 1 , wherein the position of the second covering film layer facing the connection area is hollowed out. 3 . 3. The flexible circuit board according to claim 2, wherein a boundary line is formed at the junction of the circuit area and the connection area of the transparent flexible substrate, and the second covering film layer and the junction A first distance is formed between the lines, a second distance is formed between the second circuit layer and the boundary line, and the second distance is greater than the first distance. 4. The flexible circuit board according to claim 3, wherein the first cover film layer and the second cover film layer are transparent film layers. 5 . The flexible circuit board according to claim 1 , wherein the second covering layer is made of a transparent material and covers the connection area of the flexible circuit board. 6. The flexible circuit board according to claim 5, wherein a boundary line is formed at the junction of the circuit area and the connection area of the transparent flexible substrate, and the second circuit layer and the boundary line A second distance is formed between them. 7. The flexible circuit board according to claim 6, wherein the first covering film layer is a transparent film layer. 8. A circuit connection structure, characterized in that it comprises a flexible circuit board as claimed in any one of claims 1-7, a transparent anisotropic conductive adhesive film and a device with a connection pad, the pad and The connection pads are provided in one-to-one correspondence, and the anisotropic conductive adhesive film is placed between the pads and the connection pads to realize electrical connection. 9. The circuit connection structure according to claim 8, wherein the soldering area of the pad is smaller than the soldering area of the connection pad. 10. A mobile terminal, comprising the flexible circuit board according to any one of claims 1-7.