CN112449484B

CN112449484B - Circuit board and method for manufacturing the same

Info

Publication number: CN112449484B
Application number: CN201910811923.8A
Authority: CN
Inventors: 李卫祥
Original assignee: Avary Holding Shenzhen Co Ltd; Qing Ding Precision Electronics Huaian Co Ltd
Current assignee: Avary Holding Shenzhen Co Ltd; Qing Ding Precision Electronics Huaian Co Ltd
Priority date: 2019-08-30
Filing date: 2019-08-30
Publication date: 2022-05-27
Anticipated expiration: 2039-08-30
Also published as: CN112449484A

Abstract

A circuit board manufacturing method comprising: a copper-clad substrate including a base layer and a first copper layer formed on one side of the base layer is provided. A blind hole is opened in the copper-clad substrate, a copper-clad layer is formed on the first copper layer, and part of the copper-clad layer is filled in the blind hole to form a conductive part. And covering a first photosensitive film on the copper plating layer, and carrying out exposure and development on the first photosensitive film to obtain a first photosensitive pattern in a trapezoidal structure, wherein the first photosensitive pattern covers the conductive part and the part of the copper plating layer surrounding the conductive part. And etching the copper-plated layer through the first photosensitive pattern to obtain a welding pad on the conductive part, wherein the welding pad comprises a third surface far away from the first copper layer and a bent fourth surface formed by extending from the third surface to the first copper layer. And stripping the first photosensitive pattern and etching the first copper layer to obtain a first conductive circuit layer. The circuit board manufacturing method provided by the invention can avoid the circuit board from being layered and exploded. In addition, the invention also provides a circuit board.

Description

Circuit board and method for manufacturing the same

Technical Field

The invention relates to a circuit board and a manufacturing method thereof.

Background

In the prior art, a solder pad in a flexible circuit board is usually formed by a method of selectively plating hole copper, the edge corner of the solder pad formed by local copper plating is usually a right angle, and after a covering layer is subsequently laminated, the thickness of the covering layer at the edge of the solder pad is obviously smaller than that of the covering layer in other areas, so that the flexible circuit board is easy to delaminate and burst under thermal impact such as reflow soldering, heat storage and the like, and the yield is reduced.

Disclosure of Invention

In view of this, the present invention provides a method for manufacturing a circuit board capable of increasing the yield of the circuit board.

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

A method of manufacturing a circuit board, comprising the steps of:

providing a copper-clad substrate, wherein the substrate comprises a base layer and a first copper layer formed on one side of the base layer.

And forming at least one blind hole in the copper-clad substrate, wherein the blind hole penetrates through the first copper layer and the base layer.

And electroplating to form a copper plating layer on the first copper layer, wherein part of the copper plating layer is filled in the blind hole to form a conductive part.

Covering a first photosensitive film on the copper plating layer, wherein the first photosensitive film comprises an exposure area, and the exposure area corresponds to the conductive part and a partial area of the copper plating layer arranged around the conductive part.

And exposing and developing the exposure area to obtain a first photosensitive pattern, wherein the first photosensitive pattern covers the conductive part and a partial area of the copper plating layer arranged around the conductive part, the first photosensitive pattern comprises a first surface far away from the copper plating layer and a second surface close to the copper plating layer, and the width of the first surface is greater than that of the second surface.

Etching the copper plating layer to obtain a welding pad positioned on the conductive part, wherein the welding pad comprises a third surface far away from the first copper layer and a fourth surface formed by extending the edge of the third surface towards the first copper layer, and the fourth surface is a curved surface.

And stripping the first photosensitive pattern, and etching the first copper layer which is not covered by the welding pad, thereby obtaining a first conductive circuit layer.

Further, still include: and forming a first covering film on the first conductive circuit layer.

Further, the copper-clad substrate further includes a second copper layer disposed on a side of the substrate opposite to the first copper layer, the second copper layer closes a bottom of the blind via, and the conductive portion is electrically connected to the second copper layer and the first copper layer, and the method further includes:

covering a second photosensitive film on the second copper layer, wherein the second photosensitive film is not exposed when the exposure area is exposed and developed, so that the second photosensitive film is removed after the development.

Further, still include: and etching the second copper layer to obtain a second conductive circuit layer.

Further, a second cover film is formed on the second conductive circuit layer.

A circuit board, comprising: the circuit board comprises a base layer and a first conductive circuit layer arranged on one side of the base layer, wherein at least one blind hole penetrates through the base layer and the first conductive circuit layer, and a conductive part is filled in each blind hole; and at least one welding pad, formed on the first conductive circuit layer, wherein each welding pad is electrically connected with one of the conductive parts, the welding pad comprises a surface far away from the first conductive circuit layer and another surface formed by extending the edge of the surface towards the first conductive circuit layer, and the other surface is a curved surface.

Further, a first cover film is disposed on the first conductive trace layer.

Furthermore, the circuit board further comprises a second conductive circuit layer, and the second conductive circuit layer is arranged on one side, opposite to the first conductive circuit layer, of the base layer.

Further, the second conductive circuit layer and the first conductive circuit layer are electrically conducted through the conductive part.

Furthermore, a second cover film is arranged on the second conductive circuit layer.

According to the circuit board manufacturing method provided by the invention, the outer surface of the welding pad is inclined towards the first conductive circuit layer, so that the thickness of the insulating covering layer at the edge of the welding pad is increased after the welding pad covers the first insulating covering layer, the welding pad is prevented from being layered and exploded from the edge, and the yield is improved.

Drawings

Fig. 1 is a cross-sectional view of a substrate provided by an embodiment of the present invention.

Fig. 2 is a cross-sectional view of the substrate of fig. 1 after blind vias are formed therein.

Fig. 3 is a cross-sectional view of a through-hole after a copper plating layer is formed by plating on the substrate of fig. 2.

Fig. 4 is a cross-sectional view of the substrate of fig. 3 after a first photosensitive film is laminated thereon and exposed.

Fig. 5 is a cross-sectional view of the substrate of fig. 4 after exposure and development.

Fig. 6 is a cross-sectional view of the substrate of fig. 5 after an etch copper removal process.

Fig. 7 is a cross-sectional view of the substrate of fig. 6 after the first photosensitive film is peeled off.

Fig. 8 is a cross-sectional view of the substrate of fig. 7 after lamination, exposure, development, and etching.

Fig. 9 is a cross-sectional view of a circuit board of an embodiment provided by the present invention.

Description of the main elements

The following detailed description will further illustrate the invention in conjunction with the above-described figures.

Detailed Description

The circuit board 100 and the manufacturing method thereof according to the present invention will be described in detail with reference to fig. 1 to 9 and the embodiments.

Referring to fig. 1 to 9, a first embodiment of the invention provides a method for manufacturing a circuit board 100, including the following steps:

s1 referring to fig. 1, a copper clad substrate 10 is provided, wherein the copper clad substrate 10 includes a base layer 11 and a first copper layer 12 formed on one side of the base layer 11.

Further, the base layer 11 is a resin layer, such as Polyimide (PI), Polyethylene Terephthalate (PET), or Polyethylene Naphthalate (PEN).

S2 referring to fig. 2, at least one blind via 101 is opened in the copper-clad substrate 10, and the blind via 101 penetrates through the first copper layer 12 and the base layer 11.

S3 referring to fig. 3, a copper plating layer 14 is formed on the first copper layer 12 by electroplating, and a portion of the copper plating layer 14 is filled in the blind via 101 to form a conductive portion 141. The blind hole 101 is filled with copper by plating copper on the first copper layer 12, so that the risk of local filling leakage is avoided, and the resistance of the conductive part 141 to over-cooling or over-heating impact is improved.

S4 referring to fig. 4, covering a first photosensitive film 15 on the copper plating layer 14, wherein the first photosensitive film 15 includes an exposure region 151, and the exposure region 151 corresponds to the conductive portion 141 and a partial region of the copper plating layer 14 surrounding the conductive portion 141.

S5, referring to fig. 5, the exposure region 151 is exposed and developed to obtain a first photosensitive pattern 152, the first photosensitive pattern 152 covers the conductive portion 141 and a partial region of the copper plating layer 14 disposed around the conductive portion 141, the first photosensitive pattern 152 includes a first surface 1521 far away from the copper plating layer 14 and a second surface 1522 close to the copper plating layer 14, and a width L1 of the first surface 1521 is greater than a width L2 of the second surface 1522.

In this embodiment, the exposure region 151 is irradiated with low-energy light and the irradiation time is controlled so that the first surface 1521 irradiated with light in the thickness direction of the first photosensitive film 15 is more completely polymerized than the second surface 1522 irradiated with light away therefrom, and the first photosensitive pattern 152 having a trapezoidal cross section is formed after development.

In another embodiment, the exposed region 151 may be further over-developed to form the first photosensitive pattern 152 having a trapezoidal cross-section.

S6, referring to fig. 6, the copper plating layer 14 is etched to obtain a pad 142 on the conductive portion 141, the pad 142 includes a third surface 1421 far away from the first copper layer 12 and a fourth surface 1422 formed by extending from an edge of the third surface 1421 to a position near the first copper layer 12, and the fourth surface 1422 is bent toward the first copper layer 12. Since the cross section of the first photosensitive pattern 152 is trapezoidal, the etching solution bites the copper plating layer 14 from the corner between the side surface of the first photosensitive pattern 152 and the copper plating layer 14, so that the fourth surface 1422 is bent toward the first copper layer 12.

S7, please refer to fig. 7-8, peeling off the first photosensitive pattern 152; and etching the first copper layer 12 not covered by the bonding pad 142, thereby obtaining a first conductive trace layer 16.

In the present embodiment, etching the first copper layer 12 specifically includes: covering a second photosensitive pattern 17 on the surface of the bonding pad 142, referring to fig. 7, etching the first copper layer 12 through the second photosensitive pattern 17 to obtain the first conductive trace layer 16, so that the bonding pad 142 corresponds to the first conductive trace layer 16.

In this embodiment, step S7 further includes:

referring to fig. 9, a first cover film 18 is laminated on the first conductive trace layer 16, and the edge of the fourth surface 1422 is bent toward the first copper layer 12, so that the thickness d at the edge of the bonding pad 142 is increased, thereby preventing the bonding pad 142 from delaminating and bursting from the edge, and improving the yield.

In this embodiment, referring to fig. 1 to 5, the copper-clad substrate 10 further includes a second copper layer 13, the second copper layer 13 is disposed on a side of the base layer 11 opposite to the first copper layer 12, and a side of the second copper layer 13 close to the base layer 11 is exposed at the bottom of the blind via 101, and the conductive portion 141 is electrically connected to the second copper layer 13 and the first copper layer 12, wherein the step S5 further includes: a second photosensitive film 19 is covered on the second copper layer 13, and the second photosensitive film 19 is not exposed when the exposure region 151 is exposed and developed, so that the second photosensitive film 19 is removed after the development.

In other embodiments of the present invention, the second copper layer 13 may also have a larger thickness, so that the second copper layer 13 is not completely etched by the etching solution.

Referring to fig. 7-8, in the present embodiment, step S6 further includes forming a third photosensitive film (not shown) on the second copper layer 13, obtaining a third photosensitive pattern 191 through exposure and development, and etching the second copper layer 13 through the third photosensitive pattern 191 to obtain the second conductive trace layer 20.

Referring to fig. 9, in the present embodiment, after the step S6, a second cover film 21 is further pressed on the second conductive trace layer 20. In this embodiment, the first cover film 18 and the second cover film 21 include an adhesive layer 181 and an insulating layer 182 laminated on the adhesive layer 181. The adhesive layer 181 may be made of epoxy resin, and the insulating layer 182 may be made of polyimide.

In this embodiment, the blind hole 101 is formed by laser processing, and the cross section of the blind hole 101 is substantially trapezoidal, and the width of the opening is greater than the width of the bottom. In other embodiments of the present invention, the cross section of the blind hole 101 may be rectangular, and the size of the blind hole 101 is set according to specific requirements.

Referring to fig. 8, a circuit board 100 according to an embodiment of the present invention includes a base layer 11, a first conductive trace layer 16 disposed on one side of the base layer 11, at least one blind hole 101 formed through the base layer and the first conductive trace layer 16, and a conductive portion 141 filled in each blind hole 101; and at least one bonding pad 142 formed on the first conductive trace layer 16, each bonding pad 142 electrically connected to one of the conductive portions 141, the bonding pad 142 includes a third surface 1422 away from the first conductive trace layer 16 and a fourth surface 1422 formed by extending an edge of the third surface 1422 toward the first conductive trace layer 16, and the fourth surface 1422 is a curved surface.

It should be understood that the above examples are only for illustrating the present invention and are not to be construed as limiting the present invention. It will be apparent to those skilled in the art that various other changes and modifications can be made in the technical spirit of the present invention within the scope of the appended claims.

Claims

1. A method of manufacturing a circuit board, comprising the steps of:

providing a copper-clad substrate, wherein the substrate comprises a base layer and a first copper layer formed on one side of the base layer;

at least one blind hole is formed in the copper-clad substrate and penetrates through the first copper layer and the base layer;

electroplating on the first copper layer to form a copper plating layer, wherein part of the copper plating layer is filled in the blind hole to form a conductive part;

covering a first photosensitive film on the copper plating layer, wherein the first photosensitive film comprises an exposure area, and the exposure area corresponds to the conductive part and a partial area of the copper plating layer arranged around the conductive part;

exposing and developing the exposure area to obtain a first photosensitive pattern, wherein the first photosensitive pattern covers the conductive part and a partial area of the copper plating layer arranged around the conductive part, the first photosensitive pattern comprises a first surface far away from the copper plating layer and a second surface close to the copper plating layer, and the width of the first surface is greater than that of the second surface;

etching the copper plating layer to obtain a welding pad positioned on the conductive part, wherein the welding pad comprises a third surface far away from the first copper layer and a fourth surface formed by extending the edge of the third surface towards the first copper layer, and the fourth surface is a curved surface;

stripping the first photosensitive pattern; and

and etching the first copper layer which is not covered by the welding pad so as to obtain a first conductive circuit layer.

2. The method for manufacturing a circuit board according to claim 1, further comprising: and forming a first covering film on the first conductive circuit layer.

3. The method of manufacturing a circuit board according to claim 1, wherein the copper-clad substrate further comprises a second copper layer provided on a side of the substrate opposite to the first copper layer, the second copper layer closing a bottom of the blind via, the conductive portion electrically connecting the second copper layer and the first copper layer, the method further comprising:

4. The method for manufacturing a circuit board according to claim 3, further comprising:

and etching the second copper layer to obtain a second conductive circuit layer.

5. The method for manufacturing a circuit board according to claim 4, further comprising forming a second coverlay film on the second conductive trace layer.

6. A circuit board, comprising:

a base layer;

the first conductive circuit layer is arranged on one side of the base layer, at least one blind hole penetrates through the base layer and the first conductive circuit layer, and each blind hole is internally filled with a conductive part; and

the welding pads are formed on the first conductive circuit layer, each welding pad is electrically connected with one of the conductive parts, each welding pad comprises one surface far away from the first conductive circuit layer and the other surface formed by extending the edge of the surface towards the first conductive circuit layer, and the other surface is a curved surface; a first cover film is arranged on the first conductive circuit layer.

7. The circuit board of claim 6, further comprising a second conductive trace layer disposed on a side of the base layer opposite the first conductive trace layer.

8. The circuit board of claim 7, wherein the second conductive trace layer is in electrical communication with the first conductive trace layer through the conductive portion.

9. The circuit board of claim 7, wherein the second conductive trace layer is provided with a second coverlay film.