CN102340933B - How to make a circuit board - Google Patents

Abstract

The invention relates to a manufacturing method of a circuit board, which comprises the steps that: two circuit substrates are provided; each circuit substrate comprises a middle layer and a first conductive layer and a second conductive layer which are respectively formed on both sides of the middle layer; each circuit substrate comprises a processing area and an edge area which surrounds and isconnected with the processing area; an adhesive tablet is provided and is provided with openings which correspond to the processing areas; the adhesive tablet is pressed between the two circuit substrates to form a pressure board, and the second conductive layers in the processing areas of the two circuit substrates are exposed in the openings; the two first conductive layers of the pressure board are manufactured into first conductive lines; and areas in the pressure board which correspond to the edge areas of the circuit substrates are cut and removed, so that two separated circuit boards are obtained.

Description

How to make a circuit board

technical field

The invention relates to the technical field of circuit boards, in particular to a method for manufacturing a circuit board with a small thickness.

Background technique

Printed Circuit Board (PCB), as the carrier of various electronic components, is widely used in the packaging of various electronic products. With the continuous development of electronic products along the trend of being light, thin, short, small, and power-saving, the manufacturing process of printed circuit boards is also facing greater challenges.

To reduce the thickness of electronic products, the thickness of flexible copper-clad substrates used to make double-sided circuit boards has been reduced from 100 microns to 36 microns, a development that has brought inconvenience to all steps of circuit board manufacturing. Especially after multiple wet processes such as coating photoresist, exposure and development, etching, removal of photoresist layer, and electroplating, the flexible copper-clad substrate will suffer from severe crush damage. In addition, during the electroplating process, the flexible copper-clad substrate is easily detached from the jig to the bottom of the electroplating tank, resulting in scrapped products. In selective electroplating, that is, attaching a dry film to one surface of a flexible copper-clad substrate, and electroplating only the other surface, the resulting product will also curl, which will make it difficult to peel off the film. If the curl is severe, the entire circuit board will be scrapped. As another example, after etching the flexible copper-clad substrate to form the outer layer circuit, the resulting product is severely wrinkled. The above phenomena are not conducive to improving production efficiency or product yield.

Contents of the invention

Therefore, it is necessary to provide a method for manufacturing a circuit board to improve production efficiency and product yield.

A method for manufacturing a circuit board, comprising the steps of: providing two circuit substrates, each circuit substrate including an intermediate layer and a first conductive layer and a second conductive layer respectively formed on both sides of the intermediate layer, each circuit substrate Each includes a processing area and an edge area surrounding and connecting the processing area; providing an adhesive sheet with an opening corresponding to the processing area; pressing the adhesive sheet between the two circuit substrates To form a laminated board, the second conductive layers in the processed areas of the two circuit substrates are exposed to the opening; the two first conductive layers of the laminated board are made into first conductive lines; and cutting and removing The region corresponding to the edge region of the circuit substrate in the laminated board, thereby obtaining two separated circuit boards.

The circuit board manufacturing method provided by this technical solution presses two circuit substrates and an adhesive sheet together to form a laminated board. Since the obtained laminated board has a relatively large thickness, the subsequent wet process will not cause the laminated board to appear. Wrinkled, curled or scrapped condition. It is beneficial to improve the yield rate of the product.

Description of drawings

FIG. 1 is a schematic structural diagram of a circuit substrate provided by an embodiment of the technical solution.

FIG. 2 is a schematic cross-sectional view of the above-mentioned circuit substrate after forming a plurality of first holes.

FIG. 3 is a schematic cross-sectional view of the second conductive circuit fabricated on the second conductive layer of the circuit substrate.

4 is a schematic cross-sectional view of the above-mentioned circuit substrate after forming a plurality of second holes and obtaining blind holes.

Fig. 5 is a schematic structural view of the adhesive sheet provided by the embodiment of the technical solution.

Fig. 6 is a schematic cross-sectional view of the obtained pressed board.

FIG. 7 is a schematic cross-sectional view after forming a conductive layer on the hole wall of the blind hole of the above-mentioned laminated board.

FIG. 8 is a schematic cross-sectional view after conductive plating layers are formed on the two first conductive layers of the above-mentioned laminated board.

FIG. 9 is a schematic cross-sectional view after the two first conductive layers of the above-mentioned laminated board are fabricated into first conductive circuits.

FIG. 10 is a schematic cross-sectional view of a circuit substrate obtained by removing the edge region of the above-mentioned laminated board.

FIG. 11 is a schematic cross-sectional view of the two sides of the above-mentioned circuit substrate after the first covering layer and the second covering layer are respectively formed.

FIG. 12 is a schematic cross-sectional view of a circuit board unit obtained by removing the connection area of the above circuit substrate.

Description of main component symbols

Circuit board 10

middle layer 11

The first conductive layer 12

The first hole 120

First side 121

Conductive Plating 122

First conductive line 123

The second conductive layer 13

Second conductive line 130

Adhesive sheet 14

Opening 140

First Overlay 150

Second Overlay 151

circuit board 16

Circuit board unit 17

Processing area 101

Borderlands 102

Product Area 103

Connection area 104

Blind hole 105

Hole wall 106

Plywood 107

Hole wall conductive layer 108

Conduction blind hole 109

Detailed ways

The manufacturing method of the circuit board provided by the technical solution will be further described in detail below in conjunction with the accompanying drawings and embodiments.

The embodiment of the technical solution provides a method for manufacturing a circuit board, which includes the following steps:

In the first step, two circuit substrates 10 as shown in FIG. 1 are provided, which include an intermediate layer 11 and a first conductive layer 12 and a second conductive layer 13 respectively formed on two sides of the intermediate layer 11 .

The circuit substrate 10 can be a double-sided copper-clad substrate or a multi-layer board. The intermediate layer 11 can be an insulating layer or an inner layer of a multi-layer board. In this embodiment, the circuit substrate 10 is a double-sided copper-clad substrate, and the intermediate layer 11 is a polyester (PET) film or a polyimide (PI) film. The first conductive layer 12 and the second conductive layer 13 may both be copper layers. The circuit substrate 10 is in the shape of a cuboid with a thickness of about 36 microns. The circuit substrate 10 includes a processing area 101 and an edge area 102 surrounding and connected to the processing area 101 . The processing area 101 is located at the center of the circuit substrate 10 . The processing area 101 includes a plurality of product areas 103 and a connection area 104 . The connecting area 104 is connected between the plurality of product areas 103 . The edge area 102 is annular. In this embodiment, the processing area 101 is square. The edge area 102 is a square frame. The number of the product areas 103 is four, and the four product areas 103 are arranged in an array. The connection area 104 is in the shape of a "cross". Both the first conductive layer 12 and the second conductive layer 13 may be copper foil.

The second step is to etch the first conductive layer 12 to form a plurality of first holes 120 at predetermined positions in the first conductive layer 12 to obtain the structure shown in FIG. 2 . The plurality of first holes 120 are formed by image transfer and etching processes. Specifically, a photoresist layer can be pasted on the first conductive layer 12 first, and then part of the conductive material of the first conductive layer 12 is removed through exposure, development, etching and other processes, and the remaining part of the conductive material That is, a plurality of first holes 120 are formed around. Each first hole 120 has a first side 121 connected between two opposite surfaces of the first conductive layer 12 .

In the third step, the second conductive layer 13 is fabricated into a second conductive circuit 130 to obtain the structure shown in FIG. 3 . Specifically, a photoresist layer may be formed on one side of the second conductive layer 13 first, and then part of the conductive material of the second conductive layer 13 is removed through processes such as exposure, development, and etching, and the remaining part is conductive. The material constitutes the second conductive circuit 130 .

It can be understood that the order of the third step and the second step can also be reversed, or they can be performed at the same time.

In the fourth step, a plurality of second holes 110 communicating with the plurality of first holes 120 are formed in the intermediate layer 11, so that a plurality of holes penetrating through the first holes 120 are formed in the two circuit substrates 10. A conductive layer 12 and a blind hole 105 in the intermediate layer 11 obtain a structure as shown in FIG. 4 . A portion of the second conductive layer 13 is exposed to the blind hole 105 . In this embodiment, the plurality of second holes 110 are formed by laser ablation. Specifically, carbon dioxide laser can be used to ablate the middle layer 11 . The second hole 110 has a second side 111 connected between two opposite surfaces of the intermediate layer 11 . The second side 111 and the first side 121 jointly form the hole wall 106 of the blind hole 105 .

The fifth step is to provide an adhesive sheet 14 as shown in FIG. 5 , which has an opening 140 corresponding to the processing area 101 .

The main material of the adhesive sheet 14 can be acrylic or epoxy resin. There are usually release protective films on both sides of the adhesive sheet 14 . The thickness of the adhesive sheet 14 ranges from 12.5 microns to 50 microns. Specifically, a rectangular parallelepiped piece roughly the same in shape and size as the circuit substrate 10 can be provided first, and then an opening 140 can be formed in the center of the piece by punching, etc., to obtain the ring-shaped adhesive piece 14 . The length and width of the opening 140 are greater than or equal to the length and width of the processing area 101 .

The sixth step is to press-bond the adhesive sheet 14 between the two circuit substrates 10 to form a press-bonded plate 107 as shown in FIG. The conductive layers 13 are all exposed to the openings 140 .

When manufacturing the laminated board 107 , the adhesive sheet 14 can be attached to the edge region 102 of the second conductive layer 13 of a circuit substrate 10 first. Then, the edge region 102 of the second conductive layer 13 of another circuit substrate 10 is bonded to the adhesive sheet 14 to obtain a bonded board. Finally, the laminated board is moved to a pressing machine for pressing, and the adhesive sheet 14 forms an adhesive layer 141 , that is, the laminated board 107 is obtained. The thickness of the laminated board 107 ranges from 80 microns to 120 microns, and both sides of the laminated board 107 are the first conductive layer 12 .

In the seventh step, a conductive layer 108 is formed on the hole wall 106 of the blind hole 105 in FIG. 6 to obtain a conductive blind hole 109 , as shown in FIG. 7 .

Specifically, an electroless copper deposition process or a shading process may be used. In this embodiment, the hole wall conductive layer 108 is formed by a shading process, and its material is carbon. The black shadow process only deposits the conductive layer on the surface of the insulating material, so the hole wall conductive layer 108 is only formed on the second side 111 of the second hole 110 of the blind hole 105 .

In the eighth step, the surfaces of the two first conductive layers 12 of the press-fit board 107, the surfaces of the hole wall conductive layers 108 of the plurality of via blind holes 109, and the second conductive layer 13 are exposed to the A conductive plated layer 122 is formed on the surface of the plurality of conducting blind holes 109, as shown in FIG. 8 .

In the ninth step, the first conductive layer 12 is fabricated into a first conductive circuit 123 to obtain a structure as shown in FIG. 9 . In this step, the conductive plating layer 122 is fabricated into a first conductive circuit 123 together with the first conductive layer 12 . A photoresist layer can be formed on one side of the conductive plating layer 122 first, and then a part of the conductive material of the first conductive layer 12 and the conductive plating layer 122 is removed through processes such as exposure, development, etching, etc., and the remaining part of the conductive material That is, the first conductive line 123 is formed.

In the tenth step, the region corresponding to the edge region 102 of the circuit substrate 10 in the laminated board 107 is cut and removed to obtain two separated circuit boards 16 as shown in FIG. 10 . The pressing board 107 can be cut by a forming machine. Since the length and width of the opening 140 are greater than or equal to the length and width of the processing area 101, the adhesive layer 141 formed on the edge area 102 after lamination is also separated from the pressing plate 107 along with the edge area 102, Two separate circuit boards 16 formed with the first conductive trace 123 , the via blind hole 109 and the second conductive trace 130 can be obtained.

In the eleventh step, the first cover layer 150 and the second cover layer 151 covering the first conductive circuit 123 and the second conductive circuit 130 are formed on both sides of the above-mentioned circuit board 16, so as to obtain the structure shown in FIG. 11 . In this embodiment, the first covering layer 150 covering the first conductive circuit 123 has an opening corresponding to the blind conducting hole 109 , where electronic components can be installed as required. The second covering layer 151 covers the wires of the second conductive circuit 130 and partially fills the gaps between the wires.

In the twelfth step, remove the connection area 104 of the circuit board 16 to obtain a plurality of circuit board units 17 corresponding to the plurality of product areas 103 one-to-one, as shown in FIG. 12 . In each circuit board unit 17 , the first conductive circuit 123 is signal-connected to the second conductive circuit 130 through the conductive blind hole 109 .

The circuit board manufacturing method provided by this technical solution presses two circuit substrates 10 and adhesive sheets 14 together to form a laminated board 107. Since the laminated board 107 obtained in the sixth step has a relatively large thickness, the subsequent seventh step The electroless copper deposition process or black shadow process, electroplating process, image transfer and etching process in the ninth step will not cause the laminated board 107 to wrinkle, curl or be scrapped. It is beneficial to improve the yield rate of the product. In addition, after forming the laminated board 107, the first conductive layer 12 on both sides can be electroplated at the same time. Compared with the traditional method of selectively electroplating a certain surface of each circuit substrate 10, it can save The step of attaching the protective film to the second conductive layer 13 and subsequent removal of the protective film not only saves the process and is beneficial to improve production efficiency, but also avoids the risk of the circuit substrate 10 falling into the electroplating tank due to its small thickness, which is beneficial to improve Product yield.

It can be understood that those skilled in the art can make various other corresponding changes and modifications according to the technical concept of the present invention, and all these changes and modifications should belong to the protection scope of the claims of the present invention.

Claims (9)

1. the manufacture method of a circuit board comprises step:

Two circuit substrates are provided, and each circuit substrate includes the intermediate layer and is formed at first conductive layer and second conductive layer of both sides, described intermediate layer respectively, each circuit substrate include the processing district with around the marginal zone that is connected described processing district;

An adhesive sheet is provided, and it has the opening corresponding with described processing district;

Before being pressed on described bonding sheet between described two circuit substrates, second conductive layer of described two circuit substrates of etching is to make second conducting wire with second conductive layer;

Described adhesive sheet is pressed between described two circuit substrates to form force fit plate, and second conductive layer in the processing district of described two circuit substrates all is exposed to described opening;

Two first conductive layers of described force fit plate all are made into first conducting wire; And

The zone corresponding with the marginal zone of described circuit substrate in the described force fit plate removed in cutting, thereby obtains the circuit board of two separation.

2. the manufacture method of circuit board as claimed in claim 1 is characterized in that, before described adhesive sheet being pressed between described two circuit substrates, etching first conductive layer is to form a plurality of first holes in first conductive layer.

3. the manufacture method of circuit board as claimed in claim 2, it is characterized in that, after in first conductive layer, forming a plurality of first holes, before described adhesive sheet being pressed between described two circuit substrates, also in the intermediate layer, form a plurality of second holes that are communicated with one by one with described a plurality of first holes, in circuit substrate, to form a plurality of blind holes that run through described first conductive layer and intermediate layer.

4. the manufacture method of circuit board as claimed in claim 2 is characterized in that, described circuit substrate is the double-sided copper-clad substrate, and described a plurality of second holes form by laser ablation.

5. the manufacture method of circuit board as claimed in claim 3 is characterized in that, after forming described force fit plate, two first conductive layers of described force fit plate is made into before first conducting wire, forms the hole wall conductive layer at the hole wall of described a plurality of blind holes.

6. the manufacture method of circuit board as claimed in claim 5 is characterized in that, the material of described hole wall conductive layer is carbon.

7. the manufacture method of circuit board as claimed in claim 5, it is characterized in that, after the hole wall of described a plurality of blind holes forms the hole wall conductive layer, described first conductive layer is made into before first conducting wire, the surface that is exposed to described a plurality of blind holes by hole wall conductive layer surface and described second conductive layer of electroplating in two first conductive layer surfaces of described force fit plate, described a plurality of blind holes forms conductive coating, when described first conductive layer was made into first conducting wire, the conductive coating of described first conductive layer surface was etched with first conductive layer.

8. the manufacture method of circuit board as claimed in claim 1 is characterized in that, after the circuit board that obtains two separation, forms first cover layer and second cover layer respectively in the both sides of each circuit board.

9. the manufacture method of circuit board as claimed in claim 1, it is characterized in that, the processing district of described circuit substrate comprises a plurality of product zone and a bonding pad, described bonding pad is connected between described a plurality of product zone, after zone corresponding with the marginal zone of described circuit substrate in the described force fit plate is removed in cutting, also remove described bonding pad, thereby obtain and described a plurality of product zone a plurality of circuit board units one to one.

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