CN219322639U

CN219322639U - Flexible circuit board

Info

Publication number: CN219322639U
Application number: CN202223273539.3U
Authority: CN
Inventors: 刘传禄; 吴双成
Original assignee: Sunwin Hubei Optoelectronic Technology Co Ltd
Current assignee: Sunwin Hubei Optoelectronic Technology Co Ltd
Priority date: 2022-12-07
Filing date: 2022-12-07
Publication date: 2023-07-07
Anticipated expiration: 2032-12-07

Abstract

The utility model provides a flexible circuit board which comprises a substrate, a first circuit layer, a second circuit layer, a first cover film, a second cover film, a cured adhesive layer, a reinforcing plate and conductive fillers, wherein the first circuit layer and the second circuit layer are respectively covered on a first surface of the substrate and a second surface opposite to the first surface, the first cover film is covered on the first circuit layer, the second cover film is covered on the second circuit layer, the second cover film is provided with the cured adhesive layer, the reinforcing plate is arranged on the cured adhesive layer, and the substrate, the first circuit layer, the second circuit layer, the first cover film, the second cover film and the cured adhesive layer are provided with structural holes penetrating through the substrate, the first circuit layer, the second circuit layer, the first cover film, the second cover film and the cured adhesive layer, and the conductive fillers are filled in the structural holes. The utility model can reduce the cost of the flexible circuit board.

Description

Flexible circuit board

Technical Field

The utility model relates to the technical field of flexible circuit board manufacturing, in particular to a flexible circuit board.

Background

At present, the flexible circuit board is characterized in that a reinforcing plate is adopted as structural support below a mounting electronic component area, components caused by the flexible characteristic of the circuit board are prevented from falling off, the reinforcing plate is mainly made of steel sheets as a support, and the conductive characteristic of a metal material of the reinforcing plate is utilized to ground a reflux signal, so that the effect of resisting electromagnetic interference of a product is achieved, and therefore, the grounding of the reinforcing plate is a rigid requirement of the flexible circuit board. The current general reinforcing plate grounding structure adopts a sandwich structure, a circuit is laminated with the reinforcing plate through conductive adhesive, and the reinforcing plate is conducted with the circuit through the conductive adhesive under the action of high temperature and high pressure. Specifically, referring to fig. 1 and 2, fig. 1 is a schematic diagram of an exploded structure of a flexible circuit board in the prior art, and fig. 2 is a cross-sectional view of the flexible circuit board in the prior art, where the flexible circuit board includes a substrate, a first circuit layer, a second circuit layer, a first cover film, a second cover film, a copper-clad layer, a conductive layer, and a reinforcing plate, the first circuit layer and the second circuit layer are respectively covered on a first surface of the substrate and a second surface opposite to the first surface, the first cover film is covered on the first circuit layer, the second cover film is covered on the second circuit layer, a conductive hole is formed on the second cover film, a copper-clad layer is covered on the second circuit layer at the bottom of the conductive hole, the conductive hole and the second cover film are coated with a conductive adhesive layer, and the reinforcing plate is disposed on the conductive adhesive layer. The reinforcing plate is pressed after being overlapped on the conductive adhesive layer, the lower surface of the conductive adhesive is extruded with the reinforcing plate to realize electrical conduction, and the upper surface of the conductive adhesive passes through the conductive hole through extrusion to realize electrical conduction with the second circuit layer. The process method leads to the fact that the conduction between the reinforcing plate and the circuit board is necessarily realized by adopting a layer of conductive adhesive. However, the price of the conductive paste is high, and thus, an improvement of the conductive structure of the existing reinforcing plate, that is, an improvement of the structure of the flexible circuit board is required to reduce the price of the flexible circuit board.

Disclosure of Invention

The utility model aims to provide a flexible circuit board so as to solve the problem of high price of the conventional flexible circuit board.

In order to solve the technical problems, the utility model provides a flexible circuit board, which comprises a substrate, a first circuit layer, a second circuit layer, a first cover film, a second cover film, a cured adhesive layer, a reinforcing plate and conductive fillers, wherein the first circuit layer and the second circuit layer are respectively covered on a first surface of the substrate and a second surface opposite to the first surface, the first cover film is covered on the first circuit layer, the second cover film is covered on the second circuit layer, a cured adhesive layer is arranged on the second cover film, the reinforcing plate is arranged on the cured adhesive layer, and structural holes penetrating through the substrate, the first circuit layer, the second circuit layer, the first cover film, the second cover film and the cured adhesive layer are formed in the substrate, the first circuit layer, the second circuit layer, the first cover film and the cured adhesive layer, and the conductive fillers are filled in the structural holes.

Optionally, the structure hole includes the first section hole, second section hole and the third section hole of intercommunication in proper order, first section hole runs through first tectorial membrane, the second section hole runs through the base plate first circuit layer with the second circuit layer, the third section hole runs through the second tectorial membrane with the solidification glue film, first section hole with the aperture in third section hole is greater than the aperture in second section hole.

Optionally, a conductive layer is disposed at a portion of the first section hole contacting the first circuit layer, a sidewall of the second section hole, and a portion of the third section hole contacting the second circuit layer.

Optionally, the conductive layer extends between the first cover film and the first circuit layer, and extends between the second cover film and the second circuit layer.

Optionally, the conductive layer is made of copper.

Optionally, the conductive layer is made by electroplating.

Optionally, the reinforcing plate is a steel plate.

Optionally, the conductive filler is conductive solder paste.

The flexible circuit board provided by the utility model has the following beneficial effects:

the connection of the reinforcing plate and the substrate can be realized through the connection of the reinforcing plate and the second covering film by the solidified adhesive layer, the reinforcing plate and the substrate are electrically connected through the conductive filler, the conductive function of the reinforcing plate is realized, the conductive adhesive is not needed, and therefore the cost of the flexible circuit board can be reduced.

Drawings

FIG. 1 is a schematic diagram of an exploded structure of a prior art flexible circuit board of the present utility model;

FIG. 2 is a cross-sectional view of a prior art flexible circuit board of the present utility model;

FIG. 3 is an exploded view of a flexible circuit board in an embodiment of the utility model;

fig. 4 is a cross-sectional view of a flexible circuit board in an embodiment of the utility model.

Reference numerals illustrate:

110-a substrate; 121-a first circuit layer; 122-a second circuit layer; 131-a first cover film; 132-a second cover film; 140-a copper-clad layer; 150-a conductive layer; 160-reinforcing plates; 170-conductive holes; 180-curing the glue layer; 190-conductive filler; 200-structural holes; 201-a first section of hole; 202-a second section of hole; 203-third section of holes; 210-conductive layer.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present utility model more apparent, the technical solutions of the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model, and it is apparent that the described embodiments are some embodiments of the present utility model, but not all embodiments of the present utility model. The components of the embodiments of the present utility model generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the utility model, as presented in the figures, is not intended to limit the scope of the utility model, as claimed, but is merely representative of selected embodiments of the utility model. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.

In the description of the present utility model, it should be noted that, directions or positional relationships indicated by terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., are directions or positional relationships based on those shown in the drawings, or are directions or positional relationships conventionally put in use of the inventive product, are merely for convenience of describing the present utility model and simplifying the description, and are not indicative or implying that the apparatus or element to be referred to must have a specific direction, be constructed and operated in a specific direction, and thus should not be construed as limiting the present utility model. Furthermore, the terms "first," "second," "third," and the like are used merely to distinguish between descriptions and should not be construed as indicating or implying relative importance.

Furthermore, the terms "horizontal," "vertical," and the like do not denote a requirement that the component be absolutely horizontal or overhang, but rather may be slightly inclined. As "horizontal" merely means that its direction is more horizontal than "vertical", and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.

In the description of the present utility model, it should also be noted that, unless explicitly specified and limited otherwise, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present utility model will be understood in specific cases by those of ordinary skill in the art.

Referring to fig. 3 and 4, fig. 3 is a schematic diagram of an exploded structure of a flexible circuit board according to an embodiment of the present utility model, and fig. 4 is a cross-sectional view of the flexible circuit board according to an embodiment of the present utility model, where the flexible circuit board includes a substrate 110, a first circuit layer 121, a second circuit layer 122, a first cover film 131, a second cover film 132, a cured adhesive layer 180, a reinforcing plate 160, and a conductive filler 190, the first circuit layer 121, the second circuit layer 122 is respectively covered on a first surface of the substrate 110 and a second surface opposite to the first surface, the first cover film 131 is covered on the first circuit layer 121, the second cover film 132 is covered on the second circuit layer 122, a cured adhesive layer 180 is disposed on the second cover film 132, the reinforcing plate 160 is disposed on the cured adhesive layer 180, the substrate 110, the first circuit layer 121, the second circuit layer 122, the first cover film 131, the second cover film 132, and the second filler layer 200 are respectively provided with holes 200, and the second cover film 132 is covered on the cured adhesive layer 180.

The connection between the reinforcing plate 160 and the substrate 110 can be realized by the connection between the reinforcing plate 160 and the second cover film 132 through the cured adhesive layer 180, and the conductive filler 190 is filled in the structural hole 200, so that the reinforcing plate 160 and the first and

second circuit layers

121 and 122 connected with the conductive filler 190 are electrically connected through the conductive filler 190, thereby realizing the conductive function of the reinforcing plate 160, and the flexible circuit board can be reduced without using conductive adhesive, because the structural holes 200 penetrating through the substrate 110, the first and

second circuit layers

121 and 122, and the first and

second cover films

131 and 180 are formed through the cured adhesive layer 180, and the conductive filler 190 is filled in the structural holes 200.

Referring to fig. 3 and 4, the structural hole 200 includes a first hole segment 201, a second hole segment 202 and a third hole segment 203 that are sequentially connected, the first hole segment 201 penetrates through the first cover film 131, the second hole segment 202 penetrates through the substrate 110, the first circuit layer 121 and the second circuit layer 122, the third hole segment 203 penetrates through the second cover film 132 and the cured adhesive layer 180, and the aperture of the first hole segment 201 and the aperture of the third hole segment 203 are larger than the aperture of the second hole segment 202, that is, the shape of the structural hole 200 on the cross section along the axial direction of the structural hole 200 is in an i shape, so that the contact area between the conductive filler 190 and the first circuit layer 121, the second circuit layer 122 and the substrate 110 can be increased, and the conductive performance of the reinforcing plate 160 can be improved.

Referring to fig. 3 and 4, a conductive layer 210 is provided at a portion where the first-stage hole 201 contacts the first circuit layer 121, a sidewall of the second-stage hole 202, and a portion where the third-stage hole 203 contacts the second circuit layer 122, and the conductive layer 210 is provided to further improve the electrical connection performance of the conductive filler 190 with the first circuit layer 121, the second circuit layer 122, and the substrate 110, so that the conductive performance of the stiffener 160 can be improved, and the first circuit layer 121 and the second circuit layer 122 can be conducted through the conductive layer 210.

Referring to fig. 4, the conductive layer 210 extends between the first cover film 131 and the first circuit layer 121 and between the second cover film 132 and the second circuit layer 122, that is, the area of the conductive layer 210 is larger than the area of the first section hole 201 and larger than the area of the third section hole 203, so that the exposure of the circuits on the first circuit layer 121 and the second circuit layer 122 on the substrate 110 can be avoided, and the conductive filler 190 is conducted with the circuit after the conductive filler 190 is filled, resulting in a short circuit of the circuit board.

The conductive layer 210 is made of copper.

The conductive layer 210 is formed by electroplating.

The reinforcing plate 160 is a steel plate.

The conductive filler 190 is a conductive solder paste.

In this embodiment, the manufacturing process of the flexible circuit board is as follows:

first, a first circuit layer 121 and a second circuit layer 122 are disposed on upper and lower surfaces of the substrate 110. Then, second-stage holes 202 are drilled in the substrate 110, the first circuit layer 121, and the second circuit layer 122. Then, a conductive layer 210 is plated on the sidewall of the second hole 202 and the portion of the end of the second hole 202 connected to the first circuit layer 121 and the second circuit layer 122, so that the conductive layer 210 includes a circular tube and flanges disposed at both ends of the circular tube. Then, the first cover film 131 provided with the first-stage holes 201 is disposed on the first circuit layer 121, and the first-stage holes 201 are aligned with the second-stage holes 202. Thereafter, the second cover film 132 provided with a portion of the third-stage holes 203 is disposed on the second circuit layer 122, and the third-stage holes 203 are aligned with the second-stage holes 202. Then, the cured adhesive layer 180 provided with a portion of the third-stage holes 203 is disposed on the reinforcing plate 160, and the third-stage holes 203 are aligned with the second-stage holes 202. Then, the reinforcing plate 160 provided with the cured adhesive layer 180 is disposed on the second cover film 132. Finally, the conductive filler 190 is filled into the structural hole 200, and the conductive filler 190 is melted, so that the conductive material is conducted with the conductive layer 210, and the conductive material is communicated with the reinforcing plate 160.

The above description is only illustrative of the preferred embodiments of the present utility model and is not intended to limit the scope of the present utility model, and any alterations and modifications made by those skilled in the art based on the above disclosure shall fall within the scope of the appended claims.

Claims

1. The flexible circuit board is characterized by comprising a substrate, a first circuit layer, a second circuit layer, a first cover film, a second cover film, a curing adhesive layer, a reinforcing plate and conductive fillers, wherein the first circuit layer and the second circuit layer are respectively covered on the first surface of the substrate and the second surface opposite to the first surface, the first cover film is covered on the first circuit layer, the second cover film is covered on the second circuit layer, the curing adhesive layer is arranged on the second cover film, the reinforcing plate is arranged on the curing adhesive layer, and the substrate, the first circuit layer, the second circuit layer, the first cover film, the second cover film and the curing adhesive layer are provided with structural holes penetrating through the substrate, the first circuit layer, the second circuit layer, the first cover film, the second cover film and the curing adhesive layer, and the conductive fillers are filled in the structural holes.

2. The flexible circuit board of claim 1, wherein the structural holes comprise a first section hole, a second section hole and a third section hole that are sequentially communicated, the first section hole penetrates through the first cover film, the second section hole penetrates through the substrate, the first circuit layer and the second circuit layer, the third section hole penetrates through the second cover film and the cured adhesive layer, and the first section hole and the third section hole have a larger pore diameter than the second section hole.

3. The flexible circuit board of claim 2, wherein a conductive layer is disposed at a portion of the first-stage hole in contact with the first circuit layer, a sidewall of the second-stage hole, and a portion of the third-stage hole in contact with the second circuit layer.

4. The flexible circuit board of claim 3, wherein the conductive layer extends between the first cover film and the first circuit layer and between the second cover film and the second circuit layer.

5. The flexible circuit board of claim 3, wherein the conductive layer is copper.

6. The flexible circuit board of claim 3 wherein the conductive layer is formed by electroplating.

7. The flexible circuit board of claim 1 wherein the stiffener is a steel plate.

8. The flexible circuit board of claim 1, wherein the conductive filler is a conductive solder paste.