CN102413646A - Manufacturing method of circuit board - Google Patents

Abstract

The invention provides a circuit board manufacturing method, comprising the steps of: providing a double-sided copper clad laminate including an insulating layer, a first copper foil layer and a second copper foil layer, the insulating layer is located between the first copper foil layer and the second copper foil between layers; a plurality of first holes are formed in the first copper foil layer by a chemical etching process, and a plurality of second holes corresponding to the plurality of first holes are formed in the second copper foil layer, and each The apertures of the first holes are greater than or equal to the apertures of the corresponding second holes; a plurality of third holes corresponding to the plurality of second holes are formed in the insulating layer by a laser ablation process, and each third hole The apertures are equal to or smaller than the apertures of the corresponding second holes, and each third hole is connected between a first hole and a second hole, thereby forming a plurality of through holes in the double-sided copper clad laminate; when exposed to A conductive layer is formed on the surface of the insulating layer in the plurality of through holes; the first copper foil layer is formed into a first conductive circuit, and the second copper foil layer is formed into a second conductive circuit.

Description

Circuit board manufacturing method

technical field

The invention relates to circuit board manufacturing technology, in particular to a circuit board manufacturing method.

Background technique

In the information, communication and consumer electronics industries, circuit boards are an indispensable and basic component of all electronic products. With the development of electronic products in the direction of miniaturization and high speed, circuit boards are also developing from single-sided circuit boards to double-sided circuit boards and multi-layer circuit boards. Double-sided circuit boards and multilayer circuit boards are widely used due to their large wiring area and high assembly density. Please refer to Takahashi, A. et al. published in IEEE Trans.on Components, Packaging, and Manufacturing in 1992 Technology's literature "High density multilayer printed circuitboard for HITAC M～880".

The double-sided circuit board has two conductive layers, and the signal connection is realized through the guide holes between the two conductive layers. The guide hole is generally formed by drilling, electroless plating and electroplating. In the prior art, generally, only the mechanical drilling process or the laser drilling process is used for the drilling process in making the guide hole. However, the manufacturing precision of mechanical drilling is not good, and although laser drilling has high precision, the speed of drilling conductive layers using laser is relatively slow and requires a long production time. Also, only UV lasers are suitable for drilling conductive layers, but the cost of using UV lasers is high.

Therefore, it is necessary to provide a circuit board manufacturing method with higher manufacturing efficiency and manufacturing accuracy.

Contents of the invention

A method for fabricating a circuit board will be described below with an embodiment.

A method for manufacturing a circuit board, comprising the steps of: providing a double-sided copper-clad laminate, the double-sided copper-clad laminate includes an insulating layer, a first copper foil layer, and a second copper foil layer, and the insulating layer is located between the first copper foil layer and the second copper foil layer. Between the two copper foil layers; a plurality of first holes are formed in the first copper foil layer by a chemical etching process, and a plurality of second holes are formed in the second copper foil layer, and the plurality of first holes are connected to the A plurality of second holes correspond one to one, and the diameter of each first hole is greater than or equal to the diameter of the second hole corresponding to it; a laser ablation process is used to form a plurality of second holes in the insulating layer one by one A plurality of corresponding third holes, the diameter of each third hole is equal to or smaller than the diameter of the corresponding second hole, and each third hole is connected between a first hole and a second hole, so that the The plurality of first holes, the plurality of second holes and the plurality of third holes form a plurality of through holes in the double-sided copper clad laminate; a conductive layer is formed on the surface of the insulating layer exposed to the plurality of through holes, Thereby conducting the first copper foil layer and the second copper foil layer; and forming the first copper foil layer into a first conductive circuit, and forming the second copper foil layer into a second conductive circuit.

In the circuit board manufacturing method of the technical solution, the first copper foil layer and the second copper foil layer are chemically etched first and then the insulating layer is ablated to produce through holes. Due to the low cost of chemical etching, laser ablation The speed of the insulating layer is faster, so that the production of the circuit board is realized with lower production cost and higher production efficiency. And, when making through holes, the aperture diameter of the first hole in the first copper foil layer is greater than or equal to the aperture diameter of the second hole of the second copper foil layer, so only need to ensure the manufacturing accuracy of the second hole during production, that is The manufacturing accuracy of the first hole can be guaranteed, that is to say, the difficulty of production is reduced. When the third hole is formed by laser ablation of the insulating layer, the diameter of the third hole is equal to or smaller than that of the second hole, thus ensuring the manufacturing accuracy of the through hole.

Description of drawings

FIG. 1 is a schematic flow chart of a method for manufacturing a circuit board provided by an embodiment of the technical solution.

FIG. 2 is a schematic cross-sectional view of a double-sided copper-clad laminate provided in an embodiment of the technical solution.

FIG. 3 is a schematic cross-sectional view after forming a first photoresist layer and a second photoresist layer on both sides of a double-sided copper-clad laminate according to an embodiment of the technical solution.

FIG. 4 is a schematic cross-sectional view after patterning the first photoresist layer and the second photoresist layer according to the embodiment of the technical solution.

Fig. 5 is a schematic cross-sectional view after etching the first copper foil layer and the second copper foil layer according to the embodiment of the technical solution.

FIG. 6 is a schematic cross-sectional view after removing the first photoresist layer and the second photoresist layer according to the embodiment of the technical solution.

7 is a schematic cross-sectional view of forming multiple through holes after laser ablation of the insulating layer of the double-sided copper-clad laminate provided by the embodiment of the technical solution.

FIG. 8 is a schematic cross-sectional view of forming a plurality of through holes into a plurality of guide holes according to an embodiment of the technical solution.

FIG. 9 is a schematic cross-sectional view after forming a third photoresist layer and a fourth photoresist layer on both sides of a double-sided copper-clad laminate according to an embodiment of the technical solution.

FIG. 10 is a schematic cross-sectional view after patterning the third photoresist layer and the fourth photoresist layer according to the embodiment of the technical solution.

FIG. 11 is a schematic cross-sectional view of forming conductive lines after etching the first copper foil layer and the second copper foil layer according to the embodiment of the technical solution.

FIG. 12 is a schematic cross-sectional view after removing the third photoresist layer and the fourth photoresist layer according to the embodiment of the technical solution.

Description of main component symbols

Double-sided copper clad laminate 10

The first copper foil layer 11

Insulation layer 13

The second copper foil layer 12

First Surface 131

Second Surface 132

The first hole 110

Second hole 120

First photoresist layer 14

Second photoresist layer 15

First opening 140

Second opening 150

The third hole 130

Through hole 100

First conductive line 111

Second conductive line 121

Third photoresist layer 17

Fourth photoresist layer 18

Third opening 170

Fourth opening 180

Double-sided circuit board 20

Detailed ways

The circuit board manufacturing method provided by the technical solution will be further described in detail below in conjunction with multiple drawings and implementation manners.

Please refer to Figure 1, the embodiment of the technical solution provides a circuit board manufacturing method, including steps:

The first step, referring to FIG. 2 , is to provide a double-sided copper-clad board 10 . The double-sided copper clad laminate 10 includes a first copper foil layer 11 , an insulating layer 13 and a second copper foil layer 12 stacked in sequence. The insulating layer 13 has a first surface 131 and a second surface 132 opposite to the first surface 131 . The first copper foil layer 11 is attached to the first surface 131, and the second copper foil layer 12 is attached to the second surface 132, that is to say, the insulating layer 13 is located between the first copper foil layer 11 and the second copper foil layer 13. Between foil layers 12. The material of the insulating layer 13 is a flexible material, such as polyimide (Polyimide, PI), polyethylene terephthalate (Polyethylene Terephthalate, PET), polyethylene naphthalate (Polyethylenenaphthalate, PEN), etc., but can also be hard materials, such as epoxy resin, glass fiber cloth, etc.

In the second step, please refer to FIG. 3 to FIG. 5 together, a plurality of first holes 110 are formed in the first copper foil layer 11 by a chemical etching process, and a plurality of second holes 120 are formed in the second copper foil layer 12 . The chemical etching process refers to the method of etching and removing materials using an etching solution. The plurality of first holes 110 correspond to the plurality of second holes 120 one by one, and the diameter of each first hole 110 is greater than or equal to the diameter of a corresponding second hole 120 .

Specifically, referring to FIG. 3 , first, a first photoresist layer 14 is formed on the surface of the first copper foil layer 11 , and a second photoresist layer 15 is formed on the surface of the second copper foil layer 12 . The first photoresist layer 14 and the second photoresist layer 15 can be positive photoresists or negative photoresists. Secondly, the first photoresist layer 14 and the second photoresist layer 15 are exposed and developed to pattern the first photoresist layer 14 and the second photoresist layer 15 . In this embodiment, a plurality of first openings 140 are formed in the first photoresist layer 14 , and a plurality of second openings 150 are formed in the second photoresist layer 15 , as shown in FIG. 4 . It should be noted that the number of the plurality of first openings 140 is not limited, and may be any natural number above two; the positions of the plurality of first openings 140 correspond to the positions of the plurality of first holes 110 to be formed; The number of the second openings 150 is not limited, and may be any natural number above two; the positions of the plurality of second openings 150 correspond to the positions of the plurality of second holes 120 to be formed. In the illustration of this embodiment, two first openings 140 and two second openings 150 are taken as an example for illustration. Again, use copper etchant to etch the first copper foil layer 11 exposed from the plurality of first openings 140 and the second copper foil layer 12 exposed from the plurality of second openings 150, so that the first copper foil layer The plurality of first holes 110 are formed in 11, and the plurality of second holes 120 are formed in the second copper foil layer 12, as shown in FIG. 5 . The first surface 131 of the insulating layer 13 is exposed in the plurality of first holes 110 , and the second surface of the insulating layer 13 is exposed in the plurality of second holes 120 . The copper etching solution may be an acidic copper chloride etching solution, an alkaline copper chloride etching solution or an etching solution of a nitric acid system. For example, the main components of the acid copper chloride etching solution include copper chloride, hydrogen peroxide, hydrochloric acid, sodium chloride, ammonium chloride, sodium chlorate and the like. Finally, referring to FIG. 6 , the first photoresist layer 14 and the second photoresist layer 15 are removed by stripping, brushing or dissolving.

In this embodiment, the diameter of each first hole 110 is approximately between 20 microns and 50 microns, and the diameter of each first hole 110 is greater than or equal to that of a corresponding second hole 120 . Specifically, the diameter of each first hole 110 is 1 to 2 times the diameter of a corresponding second hole 120 . That is to say, the diameter of each second hole 120 is between 20 microns and 100 microns. It should be noted that, in this embodiment, the diameter of each first hole 110 can be different, it only needs that the diameter of each first hole 110 is less than twice the diameter of a corresponding second hole 120 .

The third step, please refer to FIG. 7 , is to form a plurality of third holes 130 corresponding to the plurality of second holes 120 in the insulating layer 13 by a laser ablation process. Laser ablation process refers to the method of removing material by laser ablation.

Specifically, a carbon dioxide laser is used to ablate the part of the insulating layer 13 exposed to the plurality of second holes 120 from a position close to the second copper foil layer 12 toward the direction of the first copper foil layer 11, so that in the insulating layer 13 A plurality of third holes 130 corresponding to the plurality of second holes 120 is formed. Since the laser ablates the insulating layer 13 from the plurality of second holes 120 to the direction of the plurality of first holes 110 , the diameter of each third hole 130 is equal to or smaller than that of the corresponding second hole 120 . In this embodiment, the diameter of each third hole 130 is equal to the diameter of the corresponding second hole 120 . That is to say, the diameter of each third hole 130 is between 20 microns and 50 microns.

Each third hole 130 is connected between a first hole 110 and a second hole 120, so that the plurality of first holes 110, the plurality of second holes 120 and the plurality of third holes 130 are covered on both sides. A plurality of through holes 100 are formed in the copper plate 10 . That is to say, each third hole 130 and the first hole 110 and the second hole 120 communicating with it together form a through hole 100 . In this embodiment, the diameter of each third hole 130 may also be different, it only needs that the diameter of the third hole 130 is smaller than or equal to the diameter of the second hole 120 communicating with it.

The fourth step, please refer to FIG. 8, forms a conductive layer 16 on the surface of the insulating layer 13 exposed in the plurality of through holes 100, thereby making the plurality of through holes 100 into a plurality of via holes, thereby conducting the first copper Foil layer 11 and second copper foil layer 12 . The thickness of the conductive layer 16 is between 5 microns and 25 microns.

In this embodiment, the conductive layer 16 is deposited on the surface of the insulating layer 13 exposed in the plurality of through holes 100 through blackening and electroplating processes. Specifically, a conductive graphite layer (not shown) is deposited on the surface of the insulating layer 13 exposed to the plurality of through holes 100 through a blackening process, and then the surface of the conductive graphite layer and the first copper foil are deposited on the surface of the conductive graphite layer and the first copper foil through an electroplating process. Layer 11 surface and the surface of the second copper foil layer 12 are deposited electroplated copper layer, so the conductive graphite layer and the electroplated copper layer on the surface of the conductive graphite layer constitute the conductive layer 16 on the surface of the insulating layer 13, so that the first copper foil layer 11 and the second copper foil layer The two copper foil layers 12 are electrically connected through the conductive layer 16 . It should be noted that since the thickness of the conductive graphite layer is relatively thin, it is not shown in the diagram of this embodiment. In addition, the blackening process can be replaced by black shadow process, electroless copper deposition process or other related processes. Moreover, in other embodiments, the conductive layer 16 may also be formed only through a blackening process or an electroless copper deposition process. In other words, the conductive layer 16 can be a chemical copper layer, a conductive graphite layer or a multilayer structure. When the conductive layer 16 is an electroless copper layer or a conductive graphite layer, no plating material is formed on the surface of the first copper foil layer 11 and the surface of the second copper foil layer 12 . When the conductive layer 16 has a multi-layer structure, the surface of the first copper foil layer 11 and the surface of the second copper foil layer 12 are formed with plating materials. The multilayer structure can be a composite structure of a conductive graphite layer and an electroplated copper layer, or a composite structure of an electroless copper layer and an electroplated copper layer, or it can be composed of other conductive material layers that can be deposited on the surface of an insulating material together with an electroplated copper layer composite structure.

In addition, those skilled in the art can understand that when the electroplated copper layer is deposited on the surface of the conductive graphite layer, the surface of the first copper foil layer 11, and the surface of the second copper foil layer 12, due to the tip effect, the electroplated copper layer deposited on the first surface 131 The thickness may be greater than the thickness of the electroplated copper layer deposited in other parts.

In the fifth step, please refer to FIG. 9 to FIG. 12 together, the first copper foil layer 11 is formed into a first conductive circuit 111 , and the second copper foil layer 12 is formed into a second conductive circuit 121 . The process of forming the conductive lines can be chemical etching or laser ablation. In this embodiment, chemical etching is taken as an example for specific description.

First, referring to FIG. 9, a third photoresist layer 17 is formed on the surface of the electroplated copper layer on the surface of the first copper foil layer 11, and a fourth photoresist layer 17 is formed on the surface of the electroplated copper layer on the surface of the second copper foil layer 12. etchant layer 18. Next, referring to FIG. 10 , the third photoresist layer 17 is patterned by exposure and development, and the fourth photoresist layer 18 is patterned at the same time. That is, a plurality of third openings 170 are formed in the third photoresist layer 17 while a plurality of fourth openings 180 are formed in the fourth photoresist layer 18 . The pattern of the third photoresist layer 17 corresponds to the pattern of the conductive lines that need to be formed in the first copper foil layer 11, and the pattern of the fourth photoresist layer 18 corresponds to the pattern that needs to be formed in the second copper foil layer 12. Corresponds to the pattern of the conductive lines formed in . Again, referring to FIG. 11 , the first copper foil layer 11 exposed in the third openings 170 and the electroplated copper layer on its surface are etched with a copper etching solution, and the second copper foil layer 11 exposed in the fourth openings 180 is etched simultaneously. The copper foil layer 12 and the electroplated copper layer on its surface, thereby patterning the first copper foil layer 11 and the second copper foil layer 12 . That is to say, the first conductive line 111 corresponding to the pattern of the third photoresist layer 17 is formed in the first copper foil layer 11, and the pattern corresponding to the pattern of the fourth photoresist layer 17 is formed in the second copper foil layer 12. The pattern of the agent layer 18 corresponds to the second conductive circuit 121 . Finally, referring to FIG. 12 , the patterned third photoresist layer 17 and fourth photoresist layer 18 are removed to obtain a double-sided circuit board 20 . The double-sided circuit board 20 includes a first conductive circuit 111, a second conductive circuit 121 and an insulating layer 13 between the first conductive circuit 111 and the second conductive circuit 121, the first conductive circuit 111 and the second conductive circuit 121 Electrical connection is achieved through the conductive layer 16 in the plurality of vias 100 .

Certainly, those skilled in the art can understand that, after forming the first conductive circuit 111 and the second conductive circuit 121 , a step of covering the surface of the first conductive circuit 111 and the surface of the second conductive circuit 121 may also be included.

Moreover, it should be noted that the double-sided circuit board 20 can also be used to make a multi-layer circuit board. That is to say, the double-sided circuit board 20 can be pressed with more than one single-sided circuit board, double-sided circuit board or multilayer circuit board to form a multilayer circuit board; the double-sided circuit board 20 can also be combined with more than one single-sided circuit board. The surface copper-clad board is pressed and combined to form a multi-layer circuit board through a circuit manufacturing process.

In the method for making the double-sided circuit board 20 of the technical solution, the through hole 100 is made by first chemically etching the first copper foil layer 11 and the second copper foil layer 12 and then laser ablation of the insulating layer 13. The cost is low, and the speed of laser ablation of the insulating layer 13 is fast, so that the production of the double-sided circuit board 20 is realized with low production cost and high production efficiency. Moreover, when making the through hole 100, the aperture of the first hole 110 in the first copper foil layer 11 is greater than or equal to the aperture of the second hole 120 of the second copper foil layer 12, so only the second hole needs to be guaranteed during production. The manufacturing accuracy of 120 can guarantee the manufacturing accuracy of the first hole 110, that is to say, the difficulty of production is reduced. When forming the third hole 130 by laser ablation of the insulating layer 13, the ablation is performed from the second hole 120 to the first hole 110, thus ensuring the aperture range of the third hole 130 and ensuring the manufacturing accuracy of the through hole 100 .

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 (10)

1. A circuit board manufacturing method, comprising steps: A double-sided copper-clad laminate is provided, the double-sided copper-clad laminate includes an insulating layer, a first copper foil layer, and a second copper foil layer, and the insulating layer is located between the first copper foil layer and the second copper foil layer; A plurality of first holes are formed in the first copper foil layer by a chemical etching process, and a plurality of second holes are formed in the second copper foil layer, the plurality of first holes and the plurality of second holes are one by one corresponding, and the diameter of each first hole is greater than or equal to the diameter of the corresponding second hole; A plurality of third holes corresponding to the plurality of second holes are formed in the insulating layer by a laser ablation process, the diameter of each third hole is equal to or smaller than the diameter of the corresponding second hole, and each The third holes are all connected between one first hole and one second hole, so that the plurality of first holes, the plurality of second holes and the plurality of third holes form a plurality of passages in the double-sided copper clad laminate. hole; forming a conductive layer on the surface of the insulating layer exposed to the plurality of through holes, so as to conduct the first copper foil layer and the second copper foil layer; and The first copper foil layer is formed into a first conductive line, and the second copper foil layer is formed into a second conductive line. 2. The circuit board manufacturing method according to claim 1, wherein the insulating layer has opposite first and second surfaces, the first copper foil layer is in contact with the first surface, and the first copper foil layer is in contact with the first surface. The two copper foil layers are in contact with the second surface, the plurality of first holes are exposed on the first surface, and the plurality of second holes are exposed on the second surface. 3. The method for manufacturing a circuit board according to claim 1, wherein the diameter of each second hole is between 20 microns and 50 microns. 4. The circuit board manufacturing method according to claim 1, wherein the diameter of each first hole is less than twice the diameter of the corresponding second hole. 5. The method for manufacturing a circuit board according to claim 1, wherein when a plurality of third holes corresponding to a plurality of second holes are formed in the insulating layer, carbon dioxide laser is used to select from a plurality of second holes. The holes are ablated toward the plurality of first holes. 6 . The circuit board manufacturing method according to claim 1 , wherein the first copper foil layer is formed into a first conductive circuit by a chemical etching process, and the second copper foil layer is formed into a second conductive circuit by a chemical etching process. 7. The circuit board manufacturing method according to claim 1, wherein the conductive layer is a copper layer. 8. The circuit board manufacturing method according to claim 1, wherein forming a conductive layer on the surface of the insulating layer exposed in the through hole comprises the steps of: depositing a chemical copper layer or a conductive graphite layer on the surface of the insulating layer exposed in the through hole; and An electroplated copper layer is formed on the surface of the chemical copper layer or the conductive graphite layer through an electroplating process. 9. circuit board manufacturing method as claimed in claim 8, is characterized in that, when electroplating copper layer is formed on chemical copper layer surface or conductive graphite layer surface, also forms on the first copper foil layer surface and the second copper foil layer surface Electroplated copper layer. 10. The circuit board manufacturing method according to claim 1, characterized in that, after the first copper foil layer is formed into the first conductive circuit, and the second copper foil layer is formed into the second conductive circuit, after the first conductive circuit A covering layer is formed on the surface and the surface of the second conductive circuit.

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