CN115696761A

CN115696761A - Circuit board and manufacturing method thereof

Info

Publication number: CN115696761A
Application number: CN202110839273.5A
Authority: CN
Inventors: 古文琦; 林宜娴
Original assignee: Boardtek Electronics Corp
Current assignee: Boardtek Electronics Corp
Priority date: 2021-07-23
Filing date: 2021-07-23
Publication date: 2023-02-03

Abstract

The application provides a manufacturing method of a circuit board, which comprises the following steps: providing a metal-clad plate, wherein the metal-clad plate comprises an insulating layer and a metal foil layer arranged on the insulating layer, and the metal foil layer comprises a first surface which is in contact with the insulating layer and a second surface which is far away from the insulating layer; performing physical surface treatment on the second surface to reduce the surface roughness of the second surface; and carrying out circuit manufacturing on the metal foil layer to form a conductive layer, thus obtaining the circuit substrate. The application also provides a circuit board. The circuit board and the manufacturing method thereof can enable the circuit board to reach the preset signal loss degree under the control of reasonable cost.

Description

Circuit board and manufacturing method thereof

Technical Field

The present disclosure relates to the field of circuit boards, and more particularly, to a method for manufacturing a circuit board capable of reducing signal loss and cost.

Background

In electronic signal transmission, a major cause of signal loss of signal lines for high-frequency transmission is conductor loss. If the surface roughness of the metal foil increases the conductive resistance due to the skin effect, which results in an increase in the transmission loss in the high-frequency region. For this reason, non-roughened or low-roughened copper foils, such as ultra-low profile (VLP) copper foil or very low profile (HVLP) copper foil for communication, are currently selected to reduce signal loss. However, copper foils with low surface roughness are expensive, resulting in high material cost of the printed circuit board; and the copper foil with lower surface roughness has poor bonding force with resin, so that the problem of reliability is easy to occur.

Disclosure of Invention

Accordingly, there is a need for a circuit board and a method for fabricating the same that can solve the above-mentioned problems.

The first aspect of the present application provides a method for manufacturing a circuit board, including the following steps:

providing a metal-clad plate, wherein the metal-clad plate comprises an insulating layer and a metal foil layer arranged on the insulating layer, and the metal foil layer comprises a first surface which is in contact with the insulating layer and a second surface which is far away from the insulating layer;

performing physical surface treatment on the second surface to reduce the surface roughness of the second surface;

and carrying out circuit manufacturing on the metal foil layer to form a conductive layer, thus obtaining the circuit substrate.

In some embodiments, the step of "physically surface treating the second surface" comprises: selecting a nylon brush wheel with the mesh number of more than 1000, rotating the nylon grinding wheel at a high speed, horizontally conveying the metal-coated plate and contacting the nylon grinding wheel to brush and grind the second surface by the nylon grinding wheel, wherein the brushing pressure of the nylon grinding wheel is 1.8kg/cm ² And the conveying speed of the metal-clad plate is 1.8m/min.

In some embodiments, the step of "physically surface treating the second surface" comprises: the metal-coated plate is horizontally conveyed, and the sand blasting machine is used for blasting sand with the mesh number more than 400 to the second surface at high speed, wherein the sand blasting pressure is 2.5kg/cm ² The conveying speed of the clad metal plate was 1.7m/min.

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

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

In some embodiments, before the circuit manufacturing, the manufacturing method of the circuit board further includes: and chemically treating the metal-coated plate to form an oxidation-resistant layer on the surface of the metal foil layer.

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

In some embodiments, before the pressing, the method for manufacturing a circuit board further includes: and brown-oxidizing the circuit substrate.

The second aspect of the present application provides a circuit board, including circuit substrate, circuit substrate include the insulating layer and set up in metal foil layer on the insulating layer, metal foil layer include with the first surface that the insulating layer contacted and deviate from the second surface of insulating layer, the surface roughness of second surface is less than the surface roughness of first surface.

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

In the circuit board and the manufacturing method thereof, compared with a VLP copper foil and an HVLP copper foil, the metal-clad plate is a metal foil layer with higher surface roughness, so that the bonding force between the metal foil layer and the insulating layer is improved, and the peeling strength is improved. And, this application maintains the higher metal foil layer's of surface roughness the prerequisite of peeling off the advantage, before the preparation circuit, through physical surface treatment, has reduced the metal foil layer deviates from the surface roughness of the second surface of insulating layer to avoid leading to the too high problem of signal loss because of skin effect. In addition, the metal foil layer that roughness is lower relatively, the cost of the metal foil layer that roughness is higher is lower, and this application can make the circuit board reach predetermined signal loss degree under reasonable cost control.

Drawings

Fig. 1 is a schematic cross-sectional view of a metal-clad plate according to an embodiment of the present disclosure.

Fig. 2 is a schematic view of a metal-clad plate shown in fig. 1 being subjected to brushing treatment.

FIG. 3 is a schematic view of the metal-clad plate shown in FIG. 1 being sandblasted.

Fig. 4 is a schematic cross-sectional view of a circuit substrate according to an embodiment of the present application.

Description of the main elements

Metal-clad plate 10

Insulating layer 11

Metal foil layer 12

First surface 121

Second surface 122

Nylon grinding wheel 210

Sand blasting machine 220

Conductive layer 13

Circuit board 100

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

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art without any inventive effort based on the embodiments in the present application are within the scope of protection of the present application.

The application provides a manufacturing method of a circuit board, which comprises the following steps.

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

In this embodiment, the metal foil layers 12 are disposed on two opposite surfaces of the insulating layer 11. The metal foil layer 12 may be disposed on one surface of the insulation layer 11, and the application is not limited thereto.

The material of the insulating layer 11 may 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 may 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 disposed opposite 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 first surface 121 and the second surface 122 are both rough surfaces, and the surface roughness of the first surface 121 is less than that of the second surface 122. In the present embodiment, the metal foil layer 12 is an inverse copper foil (RTF copper foil). Compared to a VLP copper foil or HVLP copper foil, the RTF copper foil is lower in cost and has higher surface roughness, 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 a brushing treatment or a blasting treatment.

In some embodiments, a nylon grinding wheel with a mesh size of greater than 1000 is selected for the brushing process. Referring to fig. 2, the brushing process is performed in the following manner: the nylon grinding wheel 210 rotates at a high speed, when the metal-clad plate 10 horizontally moves to the second surface 122 and contacts with the rotating nylon grinding wheel 210, the nylon grinding wheel 210 brushes off part of the metal foil layer, and the brushing pressure is 1.8kg/cm ² The conveying speed of the metal-clad plate 10 was 1.8m/min.

In some embodiments, grit having a mesh size greater than 400 is selected for grit blasting. Referring to fig. 3, the sand blasting process is performed in the following manner: the metal-clad plate 10 is horizontally moved, sand is ejected to the second surface 122 at a high speed by a sand ejector 220, and the sand blasting pressure is 2.5kg/cm ² The conveying speed of the metal-clad plate 10 was 1.7m/min.

The metal-clad plate 10 of the present application was subjected to brushing treatment and blasting treatment, respectively, and the surface treatment results are shown in table 1. This application can obviously reduce surface roughness through brushing to grind behind the processing or the sand blasting.

TABLE 1

In order for the circuit board of the present application to exhibit good high-frequency characteristics, the roughness of the second surface 122 is as low as possible. Therefore, the process parameters of the brushing 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.

Step S3, referring to fig. 4, a circuit is formed on the metal foil layer to form a conductive layer 13, so as to obtain the circuit substrate 100. In some embodiments, the circuit is fabricated using a photolithographic process.

In some embodiments, before the circuit manufacturing, the method further comprises: and chemically treating the metal-clad plate to form an oxidation-resistant layer on the surface of the metal foil layer.

And S4, pressing the circuit substrates and the prepregs together to obtain the circuit board.

In some embodiments, before pressing, further comprising: and brown-oxidizing the circuit substrate. The browning has the following effects: firstly, grease, sundries and the like on the surface of the circuit substrate are removed, so that the cleanness of the circuit substrate surface is ensured; secondly, the surface metal foil layer of the circuit substrate has a layer of uniform fluff after browning, so that the bonding force between the circuit substrate and a prepreg PP is increased, and the problems of layering, board explosion and the like are avoided.

In some embodiments, after pressing, further comprising: and carrying out copper spreading treatment on the outer layer of the circuit board to form a copper-clad layer. The outer layer copper cladding of the circuit board can provide extra shielding protection for inner layer signals and can improve the heat dissipation capacity of the circuit board.

Referring to fig. 4, the present application further provides a circuit board including 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 disposed opposite 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 the method for manufacturing the same according to the embodiment of the present invention, the metal-clad plate 10 uses an inverse copper foil having a higher surface roughness than the VLP copper foil and the HVLP copper foil as the metal foil layer 12, so as to improve the bonding force between the metal foil layer 12 and the insulating layer 11 and improve the peel strength. In addition, on the premise of maintaining the peeling advantage of the metal foil layer 12 with high surface roughness, before the circuit is manufactured, the surface roughness of the second surface 122 of the metal foil layer 12 deviating from the insulating layer 11 is reduced through physical surface treatment, so that the problem of high signal loss caused by the skin effect is avoided. In addition, compared with metal foil layers (VLP copper foil and HVLP copper foil) with lower surface roughness, the metal foil layers (RTF copper foil) with higher surface roughness have lower cost, and the circuit board can reach the preset signal loss degree under the control of reasonable cost.

The above disclosure is only for the purpose of illustrating the preferred embodiments of the present application and is not to be construed as limiting the scope of the present application, which is therefore intended to be covered by the present application in all equivalent variations thereof.

Claims

1. The manufacturing method of the circuit board is characterized by comprising the following steps:

and performing circuit manufacturing on the metal foil layer to form a conductive layer to obtain the circuit substrate.

2. The method for manufacturing a circuit board according to claim 1, wherein the step of "physically surface-treating the second surface" includes: selecting a nylon brush wheel with the mesh number of more than 1000, rotating the nylon grinding wheel at a high speed, horizontally conveying the metal-coated plate and contacting the nylon grinding wheel to brush and grind the second surface by the nylon grinding wheel, wherein the brushing pressure of the nylon grinding wheel is 1.8kg/cm ² And the conveying speed of the metal-clad plate is 1.8m/min.

3. The method for manufacturing a circuit board according to claim 1, wherein the step of physically surface-treating the second surface comprises: the metal-clad plate is horizontally conveyed, sand grains with the mesh number larger than 400 are ejected to the second surface by a sand blasting machine at a high speed, wherein the sand blasting pressure is 2.5kg/cm ² The conveying speed of the coated metal plate is 1.7m/min.

4. The method of manufacturing a circuit board according to claim 1, wherein the metal foil layer is an inverted copper foil.

5. The method of manufacturing a circuit board according to claim 1, wherein the insulating layer is made of a glass fiber prepreg or a carbon fiber prepreg.

6. The method for manufacturing a circuit board according to claim 1, further comprising, before performing the circuit manufacturing: and chemically treating the metal-coated plate to form an oxidation-resistant layer on the surface of the metal foil layer.

7. The method of manufacturing a circuit board according to claim 1, further comprising: and pressing the circuit substrates and the prepregs together to obtain the circuit board.

8. The method for manufacturing a circuit board according to claim 7, further comprising, before the press-fitting: and performing brown oxidation on the circuit substrate.

9. The circuit board is characterized by comprising a circuit substrate, wherein the circuit substrate comprises an insulating layer and a metal foil layer arranged on the insulating layer, the metal foil layer comprises a first surface which is in contact with the insulating layer and a second surface which is deviated from the insulating layer, and the surface roughness of the second surface is smaller than that of the first surface.

10. The circuit board of claim 9, wherein the metal foil layer is an inverted copper foil.