CN115226304A - Circuit board and method for manufacturing the same - Google Patents

Abstract

A method for manufacturing a circuit board, the method comprising the steps of: providing a copper clad laminate, the copper clad laminate comprising a base layer, a first metal layer and a second metal layer; opening a groove through the first metal layer and the base layer by laser drilling; The groove is filled with conductive paste, the conductive paste located in the groove forms a conductive column, and the conductive paste protruding from the surface of the first metal layer forms a pad; laser drilling is used to open a hole through the pad, the conductive column and the second metal layer. through holes; the first metal layer and the second metal layer are respectively made into the first circuit layer and the second circuit layer, the first circuit layer and the second circuit layer both include a welding area, and the welding pad is arranged on the first circuit layer located in the welding area. On the circuit layer, the circuit board is obtained. The manufacturing method of the circuit board provided by the invention can not only ensure the flatness of the pad, but also ensure the good flexibility of the circuit board. In addition, the present invention also provides a circuit board.

Description

Circuit board and method of making the same

technical field

The present invention relates to printed circuit board technology, in particular to a circuit board and a manufacturing method thereof.

Background technique

To connect the two circuit boards, the traditional connection method is "reflow soldering". However, using the "reflow soldering" method, the entire circuit board needs to be heated. Generally, the temperature of "reflow soldering" is relatively high, which is easy to cause damage to some parts or electronic components that are not resistant to high temperature or sensitive to heat; May increase the signal transmission loss of the circuit board.

Now, two circuit boards are mostly connected by laser welding. In order to ensure that the surface of the circuit board is flat and conducive to laser welding, the circuit board needs to be copper-plated on the entire surface, that is, in addition to copper-plating on the surface of the through hole to form the pad, other positions also need copper-plating. However, full copper plating will affect the flexibility of the circuit. If you want to ensure good bending of the circuit, you need to choose copper plating only on the surface of the through hole, but choosing copper plating cannot ensure that the surface of the circuit board is flat.

SUMMARY OF THE INVENTION

In view of the above, in order to solve at least one of the above-mentioned defects, it is necessary to propose a method for manufacturing a circuit board.

In addition, the present invention also provides a circuit board manufactured by the above manufacturing method.

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

A copper clad laminate is provided, which includes a base layer and a first metal layer and a second metal layer disposed on opposite surfaces of the base layer.

The first metal layer and the second metal layer are respectively made into a first circuit layer and a second circuit layer, and both the first circuit layer and the second circuit layer include a welding area and are located in the welding area The first circuit layer is provided with a first groove portion.

A second groove portion is formed in the base layer by means of laser drilling, and the first groove portion and the second groove portion together form a groove.

A conductive paste is filled in the groove, the conductive paste also protrudes from the surface of the first circuit layer in the soldering area, and the conductive paste in the groove forms a conductive column, protruding from the The conductive paste on the surface of the first wiring layer forms a pad.

And, through holes penetrating through the pads, the conductive pillars and the second circuit layer are opened by means of laser drilling to obtain the circuit board.

In the embodiment of the present application, along the extending direction of the circuit board, the size of the second groove portion is larger than the size of the through hole, and is smaller than or equal to the size of the first groove portion.

In the embodiment of the present application, after forming the through hole, the method further includes:

In the embodiment of the present application, the second groove portion also penetrates the second circuit layer.

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

A copper clad laminate is provided, which includes a base layer and a first metal layer and a second metal layer disposed on opposite surfaces of the base layer.

A groove is opened through the first metal layer and the base layer by means of laser drilling.

A conductive paste is filled in the groove, the conductive paste also protrudes from the surface of the first metal layer, and the conductive paste located in the groove forms a conductive column, which protrudes from the first metal layer. The conductive paste on the surface forms a pad.

Through holes penetrating through the pads, the conductive pillars and the second metal layer are formed by laser drilling.

And, the first metal layer and the second metal layer are respectively made into a first circuit layer and a second circuit layer, the first circuit layer and the second circuit layer both include welding areas, and the welding A disk is arranged on the first circuit layer located in the bonding area to obtain the circuit board.

In the embodiment of the present application, along the extending direction of the circuit board, the size of the groove is larger than the size of the through hole.

In the embodiment of the present application, after fabricating the first circuit layer and the second circuit layer, the method further includes:

In the embodiment of the present application, the groove also penetrates the second circuit layer.

The present invention also provides a circuit board, comprising a base layer, a first circuit layer, a second circuit layer groove, a conductive column, a pad and a through hole, the first circuit layer is arranged on a surface of the base layer, and the The second circuit layer is disposed on the other surface of the base layer away from the first circuit layer. Both the first circuit layer and the second circuit layer include a bonding area, and the first circuit located in the bonding area The layer and the base layer are provided with grooves; the conductive pillars are arranged in the grooves; the pads protrude from the surface of the first circuit layer located in the bonding area, and are connected with the conductive pillars Electrical connection; the through hole is arranged through the pad, the conductive column and the second circuit layer.

In the embodiment of the present application, along the extending direction of the circuit board, the size of the groove is larger than the size of the through hole.

In the embodiment of the present application, the circuit board further includes a surface treatment layer disposed on the inner wall of the through hole, and the surface treatment layer further covers the pad and the first circuit located in the welding area layer and the second circuit layer.

In the embodiment of the present application, the groove is further provided through the second circuit layer.

Compared with the prior art, the manufacturing method of the circuit board provided by the present invention first forms a groove by means of laser drilling, fills the groove with a conductive paste, and the conductive paste protrudes from the surface of the first circuit layer to form a pad, and the pad is formed. For laser welding between subsequent boards. In the process of forming the pad from the conductive paste, the flatness of the pad and the thickness difference between the pad and the surrounding circuit layer are easy to control, which is favorable for laser welding between subsequent circuit boards. Then, the through hole is formed on the conductive paste by laser forming. The laser forming process of the through hole will further solidify the conductive paste at high temperature, so that the conductive paste has no fluidity. On the one hand, further irreversible curing can improve the conductivity. The hardness of the paste, on the other hand, does not affect the surface flatness of the pads during the laser via forming process. In addition, laser welding between circuit boards is realized by forming pads and through holes in parts of the circuit board, without electroplating the entire circuit board, which can ensure good flexibility of the circuit board.

Description of drawings

FIG. 1 is a schematic diagram of a copper clad laminate provided by an embodiment of the present invention.

FIG. 2 is a schematic diagram of attaching a protective film to the copper clad laminate shown in FIG. 1 .

FIG. 3 is a schematic view of forming openings in the protective film shown in FIG. 2 .

FIG. 4 is a schematic diagram of forming a third groove on the copper clad laminate shown in FIG. 3 .

FIG. 5 is a schematic diagram of filling conductive paste in the third groove shown in FIG. 4 .

FIG. 6 is a schematic diagram of forming through holes in the conductive paste shown in FIG. 5 .

FIG. 7 is a schematic diagram of forming the metal layer shown in FIG. 6 into a wiring layer.

FIG. 8 is a schematic diagram of forming a surface treatment layer in the through hole shown in FIG. 7 .

FIG. 9 is a schematic structural diagram of a circuit formed on the copper clad laminate shown in FIG. 1 .

FIG. 10 is a schematic diagram of attaching a protective film on the first circuit layer shown in FIG. 9 .

FIG. 11 is a schematic diagram of forming a second groove on the base layer shown in FIG. 10 .

FIG. 12 is a schematic diagram of filling conductive paste in the first groove and the second groove shown in FIG. 11 .

FIG. 13 is a schematic diagram of forming through holes in the conductive paste shown in FIG. 12 .

FIG. 14 is a schematic view of forming a surface treatment layer in the through hole shown in FIG. 13 .

FIG. 15 is a schematic structural diagram of a circuit board according to another embodiment of the present invention.

FIG. 16 is a schematic structural diagram of a circuit board provided by a fourth embodiment of the present invention.

Description of main component symbols

Circuit boards 100, 200, 300, 400

CCL 10

Grassroots 11

first metal layer 12

second metal layer 13

First circuit layer 14, 16

Second circuit layer 15, 17

first groove portion 18

Second groove portion 19, 20

protective film 2

Opening 21

Grooves 3, 5

conductive paste 4

Conductive post 41

pad 42

Through hole 6

Surface Treatment Layer 7

Solder Mask 8

Welding zone A

Non-welded area B

The following specific embodiments will further illustrate the present invention in conjunction with the above drawings.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terms used herein in the description of the present invention are for the purpose of describing specific embodiments only, and are not intended to limit the present invention.

An embodiment of the present invention provides a method for manufacturing a circuit board 100, and the method specifically includes the following steps:

In step S11 , referring to FIG. 1 , a copper clad laminate 10 is provided. The copper clad laminate 10 includes a base layer 11 and a first metal layer 12 and a second metal layer 13 disposed on opposite surfaces of the base layer 11 .

In this embodiment, the material of the base layer 11 is insulating resin. Specifically, the material of the base layer 11 can be selected from epoxy resin (epoxy resin), prepreg (PP), BT resin, polyphenylene oxide (Polyphenylene Oxide, One of resins such as PPO), polyimide (PI), polyethylene terephthalate (PET) and polyethylene naphthalate (PEN).

In step S12 , please refer to FIG. 2 , a protective film 2 is covered on the first metal layer 12 .

In this embodiment, the protective film 2 may be a PET film.

In step S13 , referring to FIG. 3 , an opening 21 is formed on the protective film 2 , and part of the first metal layer 12 is exposed through the opening 21 .

In this embodiment, the size a of the opening 21 along the extending direction of the copper clad laminate 10 can be set according to the size of the required pad.

In this embodiment, the opening 21 is formed by CO ₂ laser ablation.

Step S14 , please refer to FIG. 4 , from the opening 21 , a groove 3 is formed by laser drilling along the thickness direction of the copper clad laminate 10 , and the groove 3 penetrates the first metal layer 12 and the base layer 11. The groove 3 does not penetrate the second metal layer 13 . Along the extending direction of the copper clad laminate 10 , the size b of the groove 3 is smaller than the size a of the opening 21 .

In this embodiment, after forming the grooves 3, the openings 21 and the grooves 3 are also treated by plasma to remove CO ₂ laser ablation and laser drilling. 3 Carbides left on the surface.

In this embodiment, the groove 3 may be circular, square or other shapes.

In step S15 , referring to FIG. 5 , the grooves 3 and the openings 21 are filled with a conductive paste 4 . The conductive paste 4 disposed in the groove 3 forms a conductive column 41 , and a portion of the conductive paste 4 disposed in the opening 21 forms a pad 42 .

In this embodiment, the pads 42 fill the openings 21 .

In this embodiment, the conductive paste 4 may be, but not limited to, copper paste.

In this embodiment, after the conductive paste 4 is filled, the method further includes curing the conductive paste 4 .

In step S16 , referring to FIG. 6 , the protective film 2 is removed, and a through hole 6 penetrating the pad 42 , the conductive post 41 and the second metal layer 13 is opened by laser drilling.

The through holes 6 are formed on the conductive paste 4 by means of laser drilling, and the heat generated during the laser drilling process can further solidify the conductive paste 4 at the same time, which can not only provide the chemical stability of the conductive paste 4 and ensure the stability of the electrical connection At the same time, the metal layer formed after the conductive paste 4 is cured is more firmly attached to the inner wall of the through hole 6, which improves the connection firmness during subsequent laser welding.

In this embodiment, along the extending direction of the copper clad laminate 10 , the dimension c of the through hole 6 is smaller than the dimension b of the groove 3 . By filling the opening 21 with the conductive paste 4 to form the pad 42 , the flatness of the surface of the pad 42 can be ensured, which is beneficial to subsequent laser welding. In addition, the use of the bonding pads 42 in combination with the small-diameter through holes 6 for subsequent laser welding can ensure good flexibility of the circuit board 100 .

In step S17, referring to FIG. 7, circuit fabrication is performed on the first metal layer 12 and the second metal layer 13. Specifically, the first circuit layer 14 and The second circuit layer 15, the first circuit layer 14 and the second circuit layer 15 each include a bonding area A and a non-bonding area B other than the bonding area A, and the bonding pads 42 are provided on the on the welding area A.

Step S18 , referring to FIG. 8 , a solder resist layer 8 is formed on the first circuit layer 14 and the second circuit layer 15 on the non-bonding area B, respectively, and a surface treatment layer is formed on the inner wall of the through hole 6 7. The surface treatment layer 7 also covers the pad 42 and the first circuit layer 14 and the second circuit layer 15 located in the bonding area A, thereby obtaining the circuit board 100 .

In this embodiment, the surface treatment layer 7 includes, but is not limited to, an electroless nickel plating layer or an electroless gold plating layer. Through surface treatment, the inner wall of the through hole 6, the surface of the pad 42, and the first circuit layer 14 and the second circuit layer 15 in the bonding area A are covered by the surface treatment layer 7, so as to improve the bonding strength of the pad 42 and the conductive pillar 41. The chemical stability ensures the stability of the electrical connection, enhances the stability of the bonding between the pad 42 and the first circuit layer 14 and the second circuit layer 15, thereby improving the connection strength of subsequent laser welding.

Referring to FIG. 15 , in another embodiment, the groove 5 may also be disposed through the second metal layer 13 , as shown in FIG. 15 , the groove 5 penetrates through the second circuit layer 15 . The grooves 5 are arranged through the base layer 11 and the second metal layer 13, and the manufacturing process is relatively simple. At the same time, the adhesion area of the subsequent conductive paste 4 in the grooves 5 can be improved, the adhesion can be improved, and the contact between the conductive posts 41 and the pads 42 can be enhanced. firmness, thereby improving the connection strength during subsequent laser welding.

1, 9 to 14, another embodiment of the present invention provides a manufacturing method of a circuit board 200. The main difference between the manufacturing method of the circuit board 200 provided in this embodiment and the first embodiment is that the first The sequential steps of the first circuit layer 16 and the second circuit layer 17 are different. In this embodiment, the method specifically includes the following steps:

Step S21 , referring to FIG. 1 again, a copper clad laminate 10 is provided. The copper clad laminate 10 includes a base layer 11 and a first metal layer 12 and a second metal layer 13 disposed on opposite surfaces of the base layer 11 .

In this embodiment, the material of the base layer 11 is insulating resin. Specifically, the material of the base layer 11 can be selected from epoxy resin (epoxy resin), prepreg (PP), BT resin, polyphenylene oxide (Polyphenylene Oxide, One of resins such as PPO), polyimide (PI), polyethylene terephthalate (PET) and polyethylene naphthalate (PEN).

In step S22, referring to FIG. 9, the first metal layer 12 and the second metal layer 13 are etched to form the first circuit layer 14 and the second circuit layer 15, respectively. The first circuit layer 16 and the second circuit layer 17 both include a bonding area A and a non-bonding area B other than the bonding area A, and the first circuit layer 16 located in the bonding area A A first groove portion 18 is provided.

In this embodiment, the first circuit layer 16 and the second circuit layer 17 are fabricated through processes such as lamination, exposure, development, etching, and film removal.

In step S23 , referring to FIG. 10 , the surface of the first circuit layer 16 is covered with a protective film 2 .

In this embodiment, the protective film 2 may be a PET film.

Step S24 , referring to FIG. 11 , an opening 21 is formed on the protective film 2 , and the first groove portion 18 and part of the first circuit layer 16 are exposed through the opening 21 .

In this embodiment, along the extending direction of the copper clad laminate 10 , the size a of the opening 21 can be set according to the size of the required pad.

In this embodiment, the opening 21 is formed by CO ₂ laser ablation.

In step S25 , please refer to FIG. 11 again. From the opening 21 , a second groove portion 19 connected to the first groove portion 18 is opened in the base layer 11 by means of laser drilling, and the first groove portion 18 is formed. A groove portion 18 communicates with the second groove portion 19 to form a groove 3 .

In this embodiment, along the extending direction of the copper clad laminate 10 , the dimension e of the second groove portion 19 is smaller than or equal to the dimension d of the first groove portion 18 .

In this embodiment, after the second groove portion 19 is formed, the opening 21 and the groove 3 are also treated by plasma to remove CO ₂ by laser ablation and laser drilling, and then the opening 21 is removed. and carbides left on the surface of groove 3.

In this embodiment, the second groove portion 19 may be circular, square or other shapes.

Step S26 , please refer to FIG. 12 , filling the groove 3 and the opening 21 with the conductive paste 4 . A portion of the conductive paste 4 disposed in the groove 3 forms a conductive column 41 , and a portion of the conductive paste 4 disposed in the opening 21 forms a pad 42 .

In this embodiment, the pads 42 fill the openings 21 .

In this embodiment, the conductive paste 4 may be, but not limited to, copper paste.

In this embodiment, after the conductive paste 4 is filled, the method further includes curing the conductive paste 4 .

In step S27 , referring to FIG. 13 , the protective film 2 is removed, and through holes 6 penetrating the pads 42 , the conductive pillars 41 and the second circuit layer 17 are opened by laser drilling.

The through holes 6 are formed on the conductive paste 4 by means of laser drilling, and the heat generated during the laser drilling process can further solidify the conductive paste 4 at the same time, which can not only provide the chemical stability of the conductive paste 4 and ensure the stability of the electrical connection At the same time, the metal layer formed after the conductive paste 4 is cured is more firmly attached to the inner wall of the through hole 6, which improves the connection firmness during subsequent laser welding.

In this embodiment, along the extending direction of the copper clad laminate 10 , the dimension c of the through hole 6 is smaller than the dimension e of the second groove portion 19 . The second groove portion 19 and the first groove portion 18 are filled with conductive paste 4 to form conductive posts 41 , and the openings 21 are filled with conductive paste 4 to form pads 42 , which can ensure the flatness of the pads 42 and facilitate subsequent Laser welding. In addition, using the pads 42 in combination with the small-diameter through holes 6 for subsequent laser welding can ensure good flexibility of the circuit board 200 .

Step S28 , referring to FIG. 14 , a solder resist layer 8 is formed on the first circuit layer 16 and the second circuit layer 17 located on the non-bonding area B, respectively, and a surface treatment layer is formed on the inner wall of the through hole 6 7. The surface treatment layer 7 also covers the pad 42 and the first circuit layer 16 and the second circuit layer 17 located in the bonding area A, thereby obtaining the circuit board 200 .

In this embodiment, the surface treatment layer 7 includes, but is not limited to, an electroless nickel plating layer or an electroless gold plating layer. Through surface treatment, the inner wall of the through hole 6, the surface of the pad 42, and the first circuit layer 16 and the second circuit layer 17 in the bonding area A are covered by the surface treatment layer 7, so as to improve the bonding between the pad 42 and the conductive pillar 41. The chemical stability ensures the stability of the electrical connection, enhances the stability of the bonding between the pad 42 and the first circuit layer 16 and the second circuit layer 17 , thereby improving the connection strength of subsequent laser welding.

According to the above two methods for preparing circuit boards of the present invention, the pads 42 and the through holes 6 may be formed before the circuit is fabricated, or the pads 42 and the through holes 6 may be formed after the circuit is fabricated. Therefore, the above circuit board preparation method has a wide range of applications and is not limited by the specific process. The pads 42 and the through holes 6 can be formed before and after the circuit layer is formed, so as to meet the subsequent laser welding connection with other circuit boards.

Referring to FIG. 8 , the present invention also provides a circuit board 100 manufactured by the above-mentioned manufacturing method of the circuit board 100 , the circuit board 100 includes a base layer 11 , a first circuit layer 14 , a second circuit layer 15 , grooves 3 , conductive Posts 41 , pads 42 and through holes 6 , the first circuit layer 14 and the second circuit layer 15 are disposed on two opposite surfaces of the base layer 11 , the first circuit layer 14 and the second circuit layer Each of the layers 15 includes a welding area A, and the first circuit layer 14 and the base layer 11 located in the welding area A are provided with grooves 3; the conductive pillars 41 are arranged in the grooves 3; the welding The pad 42 protrudes from the surface of the first circuit layer 14 in the bonding area A, and is electrically connected to the conductive pillar 41 ; the through hole 6 penetrates the bonding pad 42 and the conductive pillar 41 and the second circuit layer 15 is provided.

In this embodiment, along the extending direction of the circuit board 100 , the dimension b of the groove 3 is larger than the dimension c of the through hole 6 . The larger size of the groove 3 is to fill the conductive paste 4 to form the conductive column 41 and the pad 42 to meet the requirements of subsequent laser welding, so the size of the groove 3 should be appropriately larger. In addition, by forming the through hole 6, electrical conduction can be formed. The grooves 3 on the circuit board 100 are filled with conductive paste 4 to form conductive pillars 41, and further protrude from the first circuit layer 14 to form pads 42. During the process of forming the pads 42 from the conductive paste, the flatness of the pads 42 In addition, the thickness difference between the pad 42 and the surrounding circuit layers is easy to control, which can ensure the flatness of the pad 42 and is beneficial to subsequent laser welding. In addition, the conductive paste 4 is combined with the small-diameter through holes 6 to practice the local laser welding connection of the circuit board, and can also ensure the good flexibility of the circuit board 100 .

In this embodiment, the circuit board 100 further includes a non-soldering area other than the soldering area A, and the first circuit layer 14 and the second circuit layer 15 located on the non-soldering area B are provided with The solder mask layer 8, the inner wall of the through hole 6 is provided with a surface treatment layer 7, and the surface treatment layer 7 also covers the pad 42 and the first circuit layer 14 and the second circuit layer 15 .

In this embodiment, the surface treatment layer 7 includes, but is not limited to, an electroless nickel plating layer or an electroless gold plating layer. Through surface treatment, a surface treatment layer 7 can be added to the inner wall of the through hole 6 and the surface of the pad 42 to improve the chemical stability of the pad 42 and the conductive column 41 to ensure the stability of the electrical connection, and to improve the subsequent laser welding. connection strength.

In this embodiment, the material of the base layer 11 is insulating resin. Specifically, the material of the base layer 11 can be selected from epoxy resin (epoxy resin), prepreg (PP), BT resin, polyphenylene oxide (Polyphenylene Oxide, One of resins such as PPO), polyimide (PI), polyethylene terephthalate (PET) and polyethylene naphthalate (PEN).

Please refer to FIG. 15 , another embodiment of the present invention further provides a circuit board 300 . The difference from the above circuit board 100 is that the groove 5 is provided through the base layer 11 and the second circuit layer 15 , at the same time, the conductive paste 4 is attached to the inner wall of the groove 5 to form a conductive column 41 , and the through hole 6 penetrates through the solder. The circuit board 300 is obtained by connecting the disk 42 and the conductive column 41 . By forming the groove 5 through the base layer 11 and the second circuit layer 15, the process is relatively simple, and at the same time, the adhesion area of the subsequent conductive paste 4 in the groove 5 can be increased, the adhesion can be improved, and the firmness of the conductive post 41 and the pad 42 can be enhanced. degree, thereby improving the connection strength during subsequent laser welding.

Referring to FIG. 14 , the present invention also provides a circuit board 200 manufactured by using the above-mentioned manufacturing method of the circuit board 200 . The circuit board 200 includes: a base layer 11 , a first circuit layer 16 , a second circuit layer 17 , grooves 3 , Conductive pillars 41 , pads 42 and through holes 6 , the first circuit layer 16 and the second circuit layer 17 are disposed on two opposite surfaces of the base layer 11 ; the first circuit layer 16 and the second circuit layer 17 Each circuit layer 17 includes a bonding area A, the first circuit layer 16 located in the bonding area A is provided with a first groove portion 18 , and the base layer 11 located in the bonding area A is provided with a second groove portion 19. The first groove portion 18 and the second groove portion 19 communicate with each other and form the groove 3 together; the conductive post 41 is arranged in the groove 3; the pad 42 protrudes It is located on the surface of the first circuit layer 16 in the bonding area A, and is electrically connected to the conductive pillars 41 ; the through holes 6 penetrate through the bonding pads 42 , the conductive pillars 41 and the first Two circuit layers 17 are provided.

In this embodiment, along the extending direction of the circuit board 200 , the dimension e of the second groove portion 19 is smaller than or equal to the dimension d of the first groove portion 18 . When the dimensions of the first groove portion 18 and the second groove portion 19 are the same, the structure of the circuit board 100 is the same. The size of the first groove portion 18 is larger than the size of the second groove portion 19 , so the two form a stepped groove 3 , and the stepped groove 3 is beneficial to improve the adhesion stability of the conductive paste 4 . In the process of forming the pads 42 from the conductive paste 4, the flatness of the pads 42 and the thickness difference between the pads 42 and the surrounding circuit layers can be easily controlled, which can ensure the flatness of the pads 42 and facilitate subsequent laser welding. In addition, the conductive paste 4 is combined with the small-diameter through holes 6 to practice the local laser welding connection of the circuit board, and can also ensure good flexibility of the circuit board 200 .

In this embodiment, the circuit board 200 further includes a non-soldering area other than the soldering area A, and the first circuit layer 16 and the second circuit layer 17 located on the non-soldering area B are provided with The solder mask layer 8, the inner wall of the through hole 6 is provided with a surface treatment layer 7, and the surface treatment layer 7 also covers the pad 42 and the first circuit layer 16 and the second circuit layer 17 .

In this embodiment, the surface treatment layer 7 includes, but is not limited to, an electroless nickel plating layer or an electroless gold plating layer. Through surface treatment, a surface treatment layer 7 can be added to the inner wall of the through hole 6 and the surface of the pad 42 to improve the chemical stability of the pad 42 and the conductive column 41 to ensure the stability of the electrical connection, and to improve the subsequent laser welding. connection strength.

In this embodiment, the material of the base layer 11 is insulating resin. Specifically, the material of the base layer 11 can be selected from epoxy resin (epoxy resin), prepreg (PP), BT resin, polyphenylene oxide (Polyphenylene Oxide, One of resins such as PPO), polyimide (PI), polyethylene terephthalate (PET) and polyethylene naphthalate (PEN).

Please refer to FIG. 16 , another embodiment of the present invention further provides a circuit board 400 . The difference from the above circuit board 200 is that the second groove portion 20 is disposed through the base layer 11 and the second circuit layer 17 , and at the same time, the conductive paste 4 is attached to the inner wall of the second groove portion 20 to form conductive pillars 41 , the through holes 6 penetrate through the pads 42 and the conductive pillars 41 to obtain the circuit board 400 . By forming the second groove portion 20 through the base layer 11 and the second circuit layer 17, the process is relatively simple, and at the same time, the adhesion area of the subsequent conductive pillars 41 in the second groove portion 20 can be increased, the adhesion can be improved, and the conductive pillars 41 can be enhanced. and the firmness of the bonding pad 42, thereby improving the connection strength during subsequent laser welding.

To sum up, the manufacturing method of the circuit board provided by the present invention firstly forms a groove (referring to the second groove or the third groove) through the method of laser drilling, the groove is filled with conductive paste, and the conductive paste protrudes from the first groove. Pads are formed on the surface of the circuit layer, and the pads are used for laser welding between subsequent circuit boards. In the process of forming the pad from the conductive paste, the flatness of the pad and the thickness difference between the pad and the surrounding circuit layer are easy to control, which is favorable for laser welding between subsequent circuit boards. Then, the through hole is formed on the conductive paste by laser forming. The laser forming process of the through hole will further solidify the conductive paste at high temperature, so that the conductive paste has no fluidity. On the one hand, further irreversible curing can improve the conductivity. The hardness of the paste, on the other hand, will not affect the surface flatness of the pad during the laser via forming process. In addition, laser welding between circuit boards is realized by forming pads and through holes in parts of the circuit board, without electroplating the entire circuit board, which can ensure good flexibility of the circuit board.

Claims (10)

1. a manufacturing method of a circuit board, is characterized in that, comprises the steps: A copper clad laminate is provided, including a base layer and a first metal layer and a second metal layer disposed on opposite surfaces of the base layer; The first metal layer and the second metal layer are respectively made into a first circuit layer and a second circuit layer, and both the first circuit layer and the second circuit layer include a welding area and are located in the welding area The first circuit layer is provided with a first groove portion; A second groove portion communicated with the first groove portion is formed in the base layer by means of laser drilling, and the first groove portion and the second groove portion together form a groove; A conductive paste is filled in the groove, and the conductive paste also protrudes from the surface of the first circuit layer located in the bonding area, and the conductive paste located in the groove forms a conductive column, which protrudes from the surface of the first circuit layer. the conductive paste on the surface of the first wiring layer forms a pad; and The circuit board is obtained by opening through holes through the pads, the conductive pillars and the second circuit layer by means of laser drilling. 2 . The method for manufacturing a circuit board according to claim 1 , wherein, along the extending direction of the circuit board, the size of the second groove portion is larger than the size of the through hole and smaller than or equal to the size of the through hole. 3 . Describe the size of the first groove portion. 3 . The method for manufacturing a circuit board according to claim 1 , wherein the second groove portion also penetrates through the second circuit layer. 4 . 4. A method for manufacturing a circuit board, comprising the steps of: A copper clad laminate is provided, including a base layer and a first metal layer and a second metal layer disposed on opposite surfaces of the base layer; Opening a groove through the first metal layer and the base layer by means of laser drilling; A conductive paste is filled in the groove, the conductive paste also protrudes from the surface of the first metal layer, and the conductive paste located in the groove forms a conductive column, which protrudes from the first metal layer. The conductive paste on the surface forms a pad; Opening through holes through the pads, the conductive pillars and the second metal layer by means of laser drilling; and The first metal layer and the second metal layer are respectively made into a first circuit layer and a second circuit layer, and both the first circuit layer and the second circuit layer include a bonding area, and the bonding pads are set. The circuit board is obtained on the first circuit layer located in the bonding area. 5 . The manufacturing method of the circuit board according to claim 4 , wherein, along the extending direction of the circuit board, the size of the groove is larger than the size of the through hole. 6 . 6 . The method for manufacturing a circuit board according to claim 4 , wherein the groove further penetrates the second metal layer. 7 . 7. A circuit board, characterized in that, comprising: grassroots; a first circuit layer, disposed on a surface of the base layer; The second circuit layer is disposed on the other surface of the base layer away from the first circuit layer. Both the first circuit layer and the second circuit layer include a welding area, and the first circuit layer located in the welding area The circuit layer and the base layer are provided with grooves; a conductive column, located in the groove; a bonding pad, protruding from the surface of the first circuit layer in the bonding area, and electrically connected to the conductive column; and A through hole is provided through the pad, the conductive post and the second circuit layer. 8 . The circuit board of claim 7 , wherein, along the extending direction of the circuit board, the size of the groove is larger than the size of the through hole. 9 . 9 . The circuit board according to claim 7 , further comprising a surface treatment layer disposed on the inner wall of the through hole, the surface treatment layer further covering the pad and located in the soldering area. 10 . of the first circuit layer and the second circuit layer. 10 . The circuit board of claim 7 , wherein the groove is further provided through the second circuit layer. 11 .

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