TW202306458A - Circuit board and method for manufacturing the same - Google Patents

Abstract

A method for manufacturing a circuit board includes: providing a metal clad plate including an insulation layer and a metal foil layer disposed on the metal clad plate, the metal foil layer including a first surface in contact with the insulation layer and a second surface facing away from the insulation layer; performing physical surface treatment on the second surface to reduce the surface roughness of the second surface; forming a conductor layer from the metal clad layer to obtain the circuit board. A circuit board is further disclosed.

Description

Circuit board and manufacturing method thereof

The present application relates to the field of circuit boards, in particular to a method for manufacturing a circuit board capable of reducing signal loss and cost.

In electronic signal transmission, one of the main causes of signal loss in high-frequency transmission signal lines is conductor loss. If the surface of the metal foil is rough, the conductive resistance will increase due to the skin effect, and as a result, the transmission loss in the high-frequency region will increase. For this reason, non-roughened or low-roughened copper foils are currently selected, for example, very low profile (VLP) copper foil or very low profile (HVLP) copper foil for communication, to reduce signal loss. However, the copper foil with low surface roughness is expensive, which leads to high material cost of the printed circuit board; and the copper foil with low surface roughness has poor bonding force with resin, which is prone to reliability problems.

In view of this, it is necessary to provide a circuit board capable of solving the above technical problems and a manufacturing method thereof.

The first aspect of the present application provides a method for manufacturing a circuit board, comprising the following steps: A metal-clad board is provided, the metal-clad board includes an insulating layer and a metal foil layer disposed on the insulating layer, the metal foil layer includes a first surface in contact with the insulating layer and a surface away from the insulating layer second surface; performing a physical surface treatment on the second surface to reduce the surface roughness of the second surface; Making a circuit on the metal foil layer to form a conductive layer to obtain a circuit substrate.

In some embodiments, the step of "physically surface-treating the second surface" includes: selecting a nylon brush wheel with a mesh number greater than 1000, the nylon grinding wheel rotates at a high speed, and the metal-clad plate is horizontally conveyed and The nylon grinding wheels are in contact so that the nylon grinding wheels brush the second surface, wherein the brushing pressure of the nylon grinding wheels is 1.8 kg/cm ² , and the conveying speed of the metal-clad plate is 1.8 kg/cm 2 . m/min.

In some embodiments, the step of "physically surface-treating the second surface" includes: conveying the metal-clad sheet horizontally, and spraying sand grains with a mesh number greater than 400 to the second surface at high speed by a sandblasting machine, wherein, The blasting pressure is 2.5kg/cm ² , and the conveying speed of the metal clad plate is 1.7m/min.

In some embodiments, the metal foil layer is an inverted copper foil.

In some embodiments, the insulating layer is made of glass fiber prepreg or carbon fiber prepreg.

In some embodiments, before making the circuit, the method for making the circuit board further includes: chemically treating the metal-clad plate to form an anti-oxidation layer on the surface of the metal foil layer.

In some embodiments, the manufacturing method of the circuit board further includes: pressing together the plurality of circuit substrates and the plurality of prepregs to obtain the circuit board.

In some embodiments, before lamination, the manufacturing method of the circuit board further includes: browning the circuit substrate.

The second aspect of the present application provides a circuit board, including a circuit substrate, the circuit substrate includes an insulating layer and a metal foil layer disposed on the insulating layer, and the metal foil layer includes a first metal foil layer in contact with the insulating layer. surface and a second surface facing away from the insulating layer, the surface roughness of the second surface is smaller than the surface roughness of the first surface.

In some embodiments, the metal foil layer is an inverted copper foil.

In the circuit board provided by the present application and its manufacturing method, compared with VLP copper foil and HVLP copper foil, the metal clad plate uses a metal foil layer with a higher surface roughness to improve the contact between the metal foil layer and the insulating layer. The binding force, improve the peel strength. Moreover, on the premise of maintaining the peeling advantage of the metal foil layer with a relatively high surface roughness, the present application reduces the distance between the metal foil layer and the second surface of the insulating layer through physical surface treatment before making the circuit. Surface roughness, thereby avoiding the problem of excessive signal loss due to skin effect. In addition, compared with the metal foil layer with lower surface roughness, the cost of the metal foil layer with higher surface roughness is lower. The present application can make the circuit board reach the preset signal loss level under reasonable cost control.

The following will clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the implementation manners in the present invention, all other implementation manners obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

It should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field of the present invention. Terms used in the embodiments of the present invention are for the purpose of describing specific embodiments only, and are not intended to limit the present invention.

The present application provides a method for manufacturing a circuit board, which includes the following steps.

Step S1 , please refer to FIG. 1 , providing a metal-clad board 10 , the metal-clad board 10 includes an insulating layer 11 and a metal foil layer 12 disposed on the insulating layer 11 .

In this embodiment, the metal foil layer 12 is disposed on two opposite surfaces of the insulating layer 11 . The metal foil layer 12 may be disposed on one surface of the insulating layer 11 , which is not limited in this application.

The material of the insulating layer 11 can be a rigid material, such as glass fiber prepreg (Glass fiber prepreg), carbon fiber prepreg (Carbon fiber prepreg), etc.; the material of the insulating layer 11 can be a flexible material, such as Polyimide, epoxy resin, etc.

The metal foil layer 12 includes a first surface 121 and a second surface 122 opposite to each other. The first surface 121 is in contact with the insulating layer 11 , and the second surface 122 is disposed away from the insulating layer 11 . Both the first surface 121 and the second surface 122 are rough surfaces, and the surface roughness of the first surface 121 is smaller than the surface roughness of the second surface 122 . In this embodiment, the metal foil layer 12 is reversed copper foil (RTF copper foil). Compared with VLP copper foil or HVLP copper foil, the cost of RTF copper foil is lower, and the surface roughness of RTF copper foil is higher, thereby improving the peel strength of the metal foil layer 12 .

Step S2 , performing physical surface treatment on the second surface 122 to reduce the surface roughness of the second surface 122 . The physical surface treatment is brushing or sandblasting.

In some embodiments, a nylon grinding wheel with a mesh number higher than 1000 is selected for brushing treatment. Please refer to FIG. 2 , the brushing process adopts the following method: the nylon grinding wheel 210 rotates at a high speed, and when the metal-clad plate 10 moves horizontally until the second surface 122 contacts the rotating nylon grinding wheel 210, the nylon grinding wheel 210 brushes Part of the metal foil layer is ground away, the brushing pressure is 1.8kg/cm ² , and the conveying speed of the metal-clad plate 10 is 1.8m/min.

In some embodiments, sand particles with a mesh number greater than 400 are selected for sandblasting. Please refer to FIG. 3 , the sandblasting process adopts the following method: the metal-clad plate 10 is moved horizontally, the sandblasting machine 220 sprays sand particles to the second surface 122 at a high speed, the sandblasting pressure is 2.5kg/cm ² , and the metal-clad plate 10 is conveyed The speed is 1.7m/min.

The metal-clad panel 10 of the present application was subjected to brushing treatment and sandblasting treatment respectively, and the surface treatment results are shown in Table 1. After the application is brushed or sandblasted, the surface roughness can be significantly reduced.

Table 1 Untreated Substrate (RTF) Brushing treatment (nylon brush) Sand blasting (grit) Ra 0.99 0.58 0.73 Rz 8.51 6.65 7.05

In order to make the circuit board of the present application exhibit good high-frequency characteristics, the roughness of the second surface 122 should be as low as possible. Therefore, the process parameters of the brushing treatment or sandblasting process can be adjusted according to actual needs, so as to reduce the roughness of the second surface 122 as much as possible.

In step S3 , please refer to FIG. 4 , performing circuit fabrication on the metal foil layer to form a conductive layer 13 to obtain a circuit substrate 100 . In some embodiments, the wiring is fabricated using a photolithography process.

In some embodiments, before making the circuit, it further includes: chemically treating the metal-clad plate to form an anti-oxidation layer on the surface of the metal foil layer.

Step S4, pressing together the plurality of circuit substrates and the plurality of prepregs to obtain a circuit board.

In some embodiments, before the lamination, it further includes: browning the circuit substrate. The function of browning is: first, to remove grease and sundries on the surface of the circuit substrate, thereby ensuring the cleanliness of the circuit substrate surface; second, after browning, the surface metal foil layer of the circuit substrate has a layer of uniform fluff, In this way, the bonding force between the circuit substrate and the prepreg PP is increased, thereby avoiding problems such as delamination and explosion.

In some embodiments, after lamination, the method further includes: performing copper cladding treatment on the outer layer of the circuit board to form a copper clad layer. The copper clad on the outer layer of the circuit board can provide additional shielding protection for the inner layer signals, and can improve the heat dissipation capability of the circuit board.

Referring to FIG. 4 , the present application also provides a circuit board, which includes a circuit substrate 100 . The circuit substrate 100 includes an insulating layer 11 and a metal foil layer 12 disposed on the insulating layer 11 . The metal foil layer 12 includes a first surface 121 and a second surface 122 opposite to each other. The first surface 121 is in contact with the insulating layer 11 , and the second surface 122 is disposed away from the insulating layer 11 . The surface roughness of the second surface 122 is smaller than the surface roughness of the first surface 121 . The metal foil layer 12 is an inverted copper foil.

In the circuit board and its manufacturing method provided in the embodiments of the present application, the metal-clad board 10 uses an inverted copper foil with a higher surface roughness than VLP copper foil and HVLP copper foil as the metal foil layer 12, so as to improve the The bonding force between the metal foil layer 12 and the insulating layer 11 is improved, and the peel strength is improved. Moreover, on the premise of maintaining the peeling advantage of the metal foil layer 12 with a relatively high surface roughness, the present application reduces the distance between the metal foil layer 12 and the insulating layer 11 through physical surface treatment before making the circuit. The surface roughness of the two surfaces 122 can avoid the problem of excessive signal loss caused by the skin effect. In addition, compared with metal foil layers with lower surface roughness (VLP copper foil, HVLP copper foil), the cost of metal foil layers with higher surface roughness (RTF copper foil) is lower. This application is under reasonable cost control. Allows the board to achieve a preset level of signal loss.

In addition, those skilled in the art can also make other changes within the spirit of the present invention. Of course, these changes made according to the spirit of the present invention should be included in the scope of protection claimed by the present invention.

10: metal clad plate 11: Insulation layer 12: Metal foil layer 121: first surface 122: second surface 210: nylon grinding wheel 220: sand blasting machine 13: Conductive layer 100: circuit substrate

FIG. 1 is a schematic cross-sectional view of a metal-clad plate provided by an embodiment of the present application.

Fig. 2 is a schematic diagram of brushing the metal-clad plate shown in Fig. 1 .

FIG. 3 is a schematic diagram of sandblasting the metal-clad plate shown in FIG. 1 .

FIG. 4 is a schematic cross-sectional view of a circuit substrate provided by an embodiment of the present application.

none

11: Insulation layer

13: Conductive layer

100: circuit substrate

Claims (10)

A method for manufacturing a circuit board, comprising the steps of: A metal-clad board is provided, the metal-clad board includes an insulating layer and a metal foil layer disposed on the insulating layer, the metal foil layer includes a first surface in contact with the insulating layer and a surface away from the insulating layer second surface; performing a physical surface treatment on the second surface to reduce the surface roughness of the second surface; Making a circuit on the metal foil layer to form a conductive layer to obtain a circuit substrate. The method for making a circuit board according to claim 1, wherein the step of "physically treating the second surface" includes: selecting a nylon brush wheel with a mesh number greater than 1000, and the nylon grinding wheel is rotated at a high speed, The metal-clad plate is conveyed horizontally and is in contact with the nylon grinding wheel so that the nylon grinding wheel brushes the second surface, wherein the brushing pressure of the nylon grinding wheel is 1.8kg/cm ² , the The conveying speed of the metal-clad sheet was 1.8 m/min. The method for making a circuit board according to Claim 1, wherein the step of "physically surface-treating the second surface" includes: conveying the metal-clad plate horizontally, and spraying sand grains with a mesh size greater than 400 at high speed by a sandblasting machine To the second surface, wherein the blasting pressure is 2.5kg/cm ² , and the conveying speed of the metal clad plate is 1.7m/min. The method for manufacturing a circuit board according to claim 1, wherein the metal foil layer is reversed copper foil. The method for manufacturing a circuit board according to claim 1, wherein the insulating layer is made of glass fiber prepreg or carbon fiber prepreg. The method for manufacturing a circuit board according to claim 1, wherein, before making the circuit, it further includes: chemically treating the metal-clad plate to form an anti-oxidation layer on the surface of the metal foil layer. The method for manufacturing a circuit board according to claim 1, further comprising: pressing together the plurality of circuit substrates and the plurality of prepregs to obtain the circuit board. The method for manufacturing a circuit board according to claim 7, further comprising: browning the circuit substrate before lamination. A circuit board, including a circuit substrate, the circuit substrate includes an insulating layer and a metal foil layer disposed on the insulating layer, the metal foil layer includes a first surface in contact with the insulating layer and a surface away from the insulating layer. The second surface of the insulating layer, the surface roughness of the second surface is smaller than the surface roughness of the first surface. The circuit board according to claim 9, wherein the metal foil layer is an inverted copper foil.

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