CN1747629A - Manufacturing method of double-sided printed circuit board - Google Patents

Abstract

The present invention provides a method for manufacturing a double-sided printed circuit board. First, the copper foil on the surface of a copper foil substrate (CCL) is removed to form an insulating substrate. Then, a plurality of through holes are made in the insulating substrate, and then a layer of chemical copper is coated to form a plurality of plated through holes. Then, a conductor pattern is formed on the insulating substrate, and then a solder mask layer is formed. Finally, a plurality of openings are formed in the solder mask layer to expose contact pads, and then a protective layer is coated on the surface of each contact pad.

Description

Manufacturing method of double-sided printed circuit board

technical field

The invention provides a method for manufacturing a double-sided printed circuit board, especially a method for manufacturing a double-sided printed circuit board with ultra-fine lines and high line density.

Background technique

Most of today's electronic products must use a printed circuit board (PCB) to embed various electronic components. Therefore, the performance or durability of an electronic product has a lot to do with the quality and design of the printed circuit board. In the past, the printed circuit board industry was already a mature industry, but due to the development of electronic products towards "light, thin, short, small" and "multifunctional, fast, high energy, low price", it also relatively promotes the development of printed circuit boards. It is also trending towards high density, small holes, thin lines, thin and multi-layer.

Generally speaking, double-sided printed circuit boards with circuit layouts on both sides have been widely used in electronic devices with complex circuits, such as smart air conditioners, telephones, fax machines, etc. However, because there are circuit wires on both sides, there must be a proper electrical connection between the circuits on both sides. The "bridge" between the circuits is called a via hole. That is, the via holes formed in the printed circuit board, filled or coated with metal, are used to connect with the circuit wires on both sides. Therefore, the area of the double-sided printed circuit board is twice as large as that of the single-sided board, and because the wiring can be interlaced (can be wound from one side to the other), it is more suitable for use on circuits that are more complex than the single-sided board.

Please refer to FIG. 1 . FIG. 1 is a schematic diagram of a conventional double-sided printed circuit board after laser drilling. In the prior art, the laser drilling process is carried out on the substrate 30 (that is, the copper foil substrate) coated with a layer of copper foil 32, so in order to penetrate the copper foil layer 32 and the substrate 30, the drilling process requires It takes a long time and uses more energy, so that the aperture of the through hole 34 is larger, not only the available space on the circuit board is relatively reduced, but also because the surface of the substrate 30 is already There is a relatively thick copper foil layer 32, which increases the relative thickness of the circuit wires and reduces the degree of accumulation, or requires a wire thinning process, which increases the complexity of the process, which is not conducive to the production of ultra-fine lines and the improvement of line density.

Contents of the invention

The main purpose of the present invention is to provide a method for manufacturing a double-sided printed circuit board, so as to manufacture a printed circuit board with ultra-fine lines and increase the density of the lines.

To achieve the above purpose, the present invention provides a method for manufacturing a double-sided printed circuit board. First provide a copper clad substrate (CCL) without copper foil or an insulating substrate without copper foil, then perform a drilling process to make multiple through holes in the insulating substrate, and then insulate A layer of chemical copper is coated on the surface of the substrate and each through hole to form a plurality of plated through holes, and then a wire pattern is formed on the insulating substrate, and a layer of solder resist is formed on the insulating substrate, and finally A plurality of openings are formed in the solder resist layer to expose contact pads, and a protective layer is coated on the surface of each contact pad.

The present invention further provides a method for manufacturing a printed circuit board, which includes the following steps: providing an insulating substrate; performing a drilling process to form a plurality of through holes in the insulating substrate; A layer of chemical copper is coated on the surface of the side wall of the through hole to form a plurality of via holes; a wire pattern is formed on the surface of the insulating substrate, and the wire pattern includes at least one contact pad.

Since the present invention performs a drilling process on a copper clad substrate (CCL) without copper foil or an insulating substrate without copper foil, the thickness of the substrate is thinner than that of the conventional copper clad substrate (CCL), so it can reduce the cost of drilling. It takes a lot of time and energy, and can reduce the aperture of the via hole and the time of etching copper foil, so as to facilitate the production of printed circuit boards with ultra-fine lines and increase the density of lines.

Description of drawings

FIG. 1 is a schematic diagram of a conventional double-sided printed circuit board after laser drilling.

2 to 8 are schematic diagrams of the manufacturing method of the double-sided printed circuit board of the present invention.

Symbol Description:

30, 50 ~ insulating substrate

32, 52～copper foil

34, 54～through hole

56～chemical copper

57~via hole

58～Photoresist pattern

60～electroplated copper

62～Solder resist layer

64～open

65～contact pad

66～protective layer

Detailed ways

In order to enable your examiners to further understand the characteristics and technical content of the present invention, please refer to the following detailed description and accompanying drawings of the present invention. However, the accompanying drawings are only for reference and auxiliary description, and are not intended to limit the present invention.

Please refer to FIG. 2 to FIG. 8 . FIG. 2 to FIG. 8 are schematic diagrams of the manufacturing method of the double-sided printed circuit board of the present invention. First, provide a copper clad substrate (Copper clad laminate, CCL), this copper clad substrate includes an insulating substrate and at least one copper foil covering the surface of the insulating substrate, for example, a layer of copper foil is covered on the top and bottom as shown in Figure 2 52 insulating substrate 50. Then an etching process is performed to remove the copper foil 52 on the surface of the insulating substrate 50 , leaving only the insulating substrate 50 , as shown in FIG. 3 . The present invention can also directly use an insulating substrate without copper foil to replace the copper clad substrate (CCL), so that an etching process for removing the copper foil can be omitted.

Next, as shown in FIG. 4 , a laser drilling process is performed on the insulating substrate 50 to form a plurality of through holes 54 in the insulating substrate 50 . Another embodiment may also be to form vias for conducting the lines between the circuit boards of each layer.

As shown in FIG. 5, a surface roughening process is then performed on the surface of the insulating substrate 50 and each through-hole 54 to increase the roughness of the surface of the insulating substrate 50 and each through-hole 54, thereby improving the chemical copper resistance to the insulating substrate 50 and each through-hole. Adhesion on the surface of hole 54. Then a layer of chemical copper 56 is formed on the insulating substrate 50 and the sidewall surfaces of the through holes 54 to form a plurality of via holes 57 , as shown in FIG. 5 .

As shown in FIG. 6, a photoresist pattern 58 is then transferred to both sides of the insulating substrate 50 as a mask, and then an electroplating process is performed to cover the surface of the insulating substrate 50 that is not covered by the photoresist pattern 58. A layer of electroplated copper layer 60 is formed on the surface and the sidewall of each through hole 54 as a circuit, and the circuit includes at least one contact pad (contact pad) 65 .

Next, as shown in FIG. 7 , a stripping process, such as a stripping process, is performed to remove the photoresist pattern 58 on the insulating substrate 50, and then an etching process is performed on the insulating substrate 50 to remove the original strip. The chemical copper layer 56 is exposed under the photoresist pattern 58 after removing the photoresist pattern 58 . Generally speaking, the thickness of the copper foil 52 is usually about 10-12 μm, while the thickness of the chemical copper layer 56 is usually only about 0.1-1 μm. The copper foil 52 only has the chemical copper layer 56, so while performing this etching process, the surface and sides of the aforementioned electroplated copper layer 60 are also etched at the same time, that is to say, the present invention particularly reduces all copper on the surface of the insulating substrate 50 Layer thickness, so that this etching process only needs to remove the chemical copper layer 56 whose thickness is much lower than that of the copper foil 52. Therefore, the etched thickness of the surface and sides of the aforementioned electroplated copper layer 60 (circuit) is greatly reduced, so not only It can make thinner lines and reduce line spacing, greatly increase the density of wiring, and then produce circuit boards that meet the current needs of light, thin, and short electronic products.

As shown in FIG. 8 , a layer of solder resist layer 62 is evenly formed on the surface of the insulating substrate 50, and then an opening 64 is formed on the solder resist layer 62 above the contact pad 65 by, for example, etching to expose the contact pad 65, and finally Then form a protective layer 66 made of materials such as nickel (Ni)/gold (Au) or organic solder preservative (OSP) on the surface of the contact pad 65 to complete the manufacturing process of the double-sided printed circuit board of the present invention .

It should be noted that the present invention is also applicable to multi-layer circuit boards. The copper foils of the uppermost layer and the lowermost layer are removed, and then the aforementioned process steps are continued. In addition, multiple groups of circuit boards completed through the aforementioned manufacturing process can also be laminated to form a multi-layer circuit board.

Compared with the conventional technology, the present invention performs laser drilling process on a copper clad substrate (CCL) without copper foil or an insulating substrate without copper foil, and the substrate thickness is thicker than that of the conventional copper clad substrate (CCL) Thin, so it can greatly reduce the time and energy required for drilling, and can effectively reduce the aperture of the via hole and the conventional etching time of the wire pattern with copper foil, so as to facilitate the production of printed circuit boards with ultra-fine lines And increase the density of the line.

Claims (18)

1, a kind of manufacture method of double-sided printed-circuit board, this manufacture method includes the following step:

Provide a copper clad laminate, and this copper clad laminate includes an insulated substrate and at least one Copper Foil covers this insulated substrate surface;

Carry out an etch process, remove this Copper Foil on this insulated substrate surface;

Carry out a boring processing procedure, in this insulated substrate, to form a plurality of through holes;

In the sidewall surfaces coating last layer chemical copper of this insulated substrate and these through holes, to form a plurality of vias;

Form a wire pattern in this insulated substrate surface, this wire pattern comprises at least one contact mat;

Form the anti-welding flux layer of one deck in this insulated substrate surface, and in this anti-welding flux layer, form at least one opening, to expose this contact mat;

In this contact mat surface coated layer protective layer.

2, the manufacture method of double-sided printed-circuit board according to claim 1, wherein this boring processing procedure is to be a Laser drill processing procedure.

3, the manufacture method of double-sided printed-circuit board according to claim 1, wherein before this chemical copper of coating, other includes this insulated substrate is carried out a surface-treated step, in order to increase the adhesion of this insulated substrate surface and this chemical copper.

4, the manufacture method of double-sided printed-circuit board according to claim 3, wherein this surface treatment is to be a surface coarsening processing procedure.

5, the manufacture method of double-sided printed-circuit board according to claim 1, the step that wherein forms this wire pattern includes in addition:

With a photoresistance pattern transfer to this insulated substrate surface;

Sidewall surfaces formation one deck electro-coppering in this insulated substrate surface with these through holes;

Carry out a removing photoresistance processing procedure;

This insulated substrate is carried out an etch process, to remove this chemical copper layer that comes out.

6, the manufacture method of double-sided printed-circuit board according to claim 5, wherein this removing photoresistance processing procedure is to be a stripping processing procedure, in order to remove this photoresistance pattern.

7, the manufacture method of double-sided printed-circuit board according to claim 1, wherein the material of this protective layer is to be nickel.

8, the manufacture method of double-sided printed-circuit board according to claim 1, wherein the material of this protective layer is to be gold.

9. the manufacture method of a printed circuit board (PCB), this manufacture method includes the following step:

One insulated substrate is provided;

Carry out a boring processing procedure, in this insulated substrate, to form a plurality of through holes;

In sidewall surfaces coating one deck chemical copper of this insulated substrate and these through holes, to form a plurality of vias;

Form a wire pattern in this insulated substrate surface, this wire pattern comprises at least one contact mat.

10. the manufacture method of printed circuit board (PCB) according to claim 9, wherein this boring processing procedure is a Laser drill processing procedure.

11. the manufacture method of printed circuit board (PCB) according to claim 9, wherein before this chemical copper of coating, other includes this insulated substrate is carried out a surface-treated step, in order to increase the adhesion of this insulated substrate surface and this chemical copper.

12. the manufacture method of printed circuit board (PCB) according to claim 11, wherein this surface treatment is to be a surface coarsening processing procedure.

13. the manufacture method of printed circuit board (PCB) according to claim 9, the step that wherein forms this wire pattern includes in addition:

With a photoresistance pattern transfer to this insulated substrate surface;

Sidewall surfaces in this insulated substrate and these through holes forms one deck electro-coppering;

Carry out a removing photoresistance processing procedure;

This insulated substrate is carried out an etch process, to remove this chemical copper layer that comes out.

14. the manufacture method of printed circuit board (PCB) according to claim 13, wherein this removing photoresistance processing procedure is to be a stripping processing procedure, in order to remove this photoresistance pattern.

15. the manufacture method of printed circuit board (PCB) according to claim 9, wherein after this insulated substrate surface formed a wire pattern, this manufacture method included the following step in addition:

Form the anti-welding flux layer of one deck in this insulated substrate surface, and in this anti-welding flux layer, form at least one opening, to expose this contact mat;

In this contact mat surface coated layer protective layer.

16. the manufacture method of printed circuit board (PCB) according to claim 15, wherein the material of this protective layer is to be nickel.

17. the manufacture method of printed circuit board (PCB) according to claim 15, wherein the material of this protective layer is to be gold.

18. the manufacture method of printed circuit board (PCB) according to claim 9, wherein this insulated substrate is the copper clad laminate that removes Copper Foil for.

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