Wide-line-spacing circuit manufacturing method

Abstract

The invention relates to a wide-line-spacing circuit manufacturing method, which comprises the steps of cutting, copper paste printing, circuit copper plating, laser leading and film laminating, and is characterized in that in the copper paste printing step, low-temperature cured copper paste is printed on the surface of a base material according to a preset printing range in a silk-screen printing manner, and the preset printing range comprises a plurality of circuit areas and a plurality of leading wire areas; the line area corresponds to the position of an actual line, the lead area is used for connecting the isolated line area with the adjacent line area so as to grow a copper-plated copper layer on the surface of printed copper, and a copper paste layer is obtained after low-temperature cured copper paste is baked and cured. The method is suitable for manufacturing the circuit board with the line spacing of more than 0.3 mm, the circuit manufacturing period can be greatly shortened, the use of photo-sensitive resist and etching liquid is avoided, the generation of waste is reduced, and the method is more environment-friendly.

Description

Technical Field

[0001] This invention relates to the field of circuit board manufacturing technology, and in particular to a method for manufacturing wide-spacing circuits. Background Technology

[0002] With the rapid development of society, industrial pollution discharge requirements are becoming increasingly stringent, and people are paying more and more attention to environmental protection.

[0003] Chinese patent CN114501829A discloses a method for manufacturing a circuit board, the steps of which include providing a substrate with a conductive layer on its surface, the substrate defining a product area and a non-product area, the product area defining an adjacent first circuit area and a second circuit area; patterning the conductive layer to form a first conductive portion and a second conductive portion spaced apart and insulated from each other in the first circuit area and the second circuit area, and forming a first electroplating pad and a second electroplating pad spaced apart and insulated from each other in the non-product area; forming a patterned dry film on the first conductive portion and the second conductive portion; electroplating through a conductive lead; removing the patterned dry film; and rapid etching. This manufacturing method belongs to the mSAP process (modified semi-additive process) and is suitable for precision circuit boards with narrow linewidths.

[0004] However, some circuit board products on the market do not have very narrow linewidth requirements, such as membrane switch circuits and keyboard circuits, making the above process wasteful. This is because the process not only involves many steps and takes a long time, but also uses reagents such as photosensitive adhesive and etching solution, generating more waste and being environmentally unfriendly.

[0005] Therefore, it is necessary to design a new method to avoid the above problems. Summary of the Invention

[0006] The main objective of this invention is to provide a method for manufacturing wide-spacing circuits, which can significantly reduce the circuit manufacturing cycle, eliminate the use of photosensitive adhesive and etching solution, reduce waste generation, and be more environmentally friendly.

[0007] This invention achieves the above objective through the following technical solution: a method for manufacturing wide-spacing lines, comprising the following steps: S1. Cutting: Cutting large-size copper-clad laminates into substrates of the required production specifications; S2, Copper paste printing: Using screen printing, low-temperature curing copper paste is printed on the surface of the substrate according to a preset printing range. The preset printing range includes several circuit areas and several lead areas. The circuit areas correspond to the positions of the actual circuits. The lead areas are used to connect isolated circuit areas with adjacent circuit areas. The low-temperature curing copper paste is baked and cured to obtain a copper paste layer. S3. Copper plating of circuit: Electroplating a copper plating layer on the surface of the copper paste layer, wherein the copper paste layer and the copper plating layer constitute a circuit layer; S4, Laser Leads: The copper paste layer and copper plating layer in the lead area are removed together by laser cutting, leaving the circuit layer within the circuit design pattern area; S5. Coating and lamination: An insulating film is bonded to the surface of the copper-plated layer and then cured to obtain an insulating layer.

[0008] Specifically, the low-temperature curing copper paste is provided by Suzhou Jinyi New Material Technology Co., Ltd., with a curing temperature of 150~180℃ and a curing time of 50~80min.

[0009] Furthermore, the screen used for copper paste printing is 325 mesh, and the thickness of the copper paste layer is 15~20um.

[0010] Specifically, the forward squeegee speed for copper paste printing is 260 mm / s, and the reverse squeegee speed is 300 mm / s.

[0011] Specifically, the thickness of the copper plating layer is 10~15um, and the printing range of the copper paste layer is 10um smaller than the circuit design pattern.

[0012] The beneficial effects of the technical solution of this invention are: This method is applicable to the manufacturing of circuit boards with line spacing of 0.3mm or more. It can significantly reduce the circuit manufacturing cycle, eliminate the use of photosensitive adhesive and etching solution, reduce waste generation, and is more environmentally friendly. Attached Figure Description

[0013] Figure 1 This is a cross-sectional view showing the manufacturing process of the wide-spacing line manufacturing method in an embodiment.

[0014] The diagram is marked as follows: 1-Substrate, 2-Copper paste layer, 3-Copper plating layer, 4-Insulation layer, 5-Circuit area, 6-Lead area. Detailed Implementation

[0015] The present invention will be further described in detail below with reference to specific embodiments.

[0016] Example: like Figure 1 As shown, a method for manufacturing wide-spacing lines according to the present invention includes the following steps: S1. Cutting: Cutting large-size copper-clad laminates into substrate 1 of the required production specifications.

[0017] Cutting is done to obtain a substrate 1 with dimensions suitable for subsequent processing.

[0018] S2, Copper paste printing: Using screen printing, low-temperature curing copper paste is printed on the surface of substrate 1 according to a preset printing range. The preset printing range includes several circuit areas 5 and several lead areas 6. The circuit areas 5 correspond to the positions of the actual circuits, and the lead areas 6 are used to connect isolated circuit areas with adjacent circuit areas. After the low-temperature curing copper paste is baked and cured, copper paste layer 2 is obtained.

[0019] The low-temperature curing copper paste is provided by Suzhou Jinyi New Material Technology Co., Ltd., and its main component is a mixture of oligomeric resin and copper powder. Because screen printing cannot use molten copper (melting point 1083.4℃), resin is used as a carrier to form a copper-containing conductive layer (i.e., copper paste layer 2) after curing. Taking this low-temperature curing copper paste as an example, the curing temperature is 150~180℃, and the curing time is 50~80 minutes. The precision of copper lines prepared by screen printing is not as high as that of the mSAP process, so it is generally used for the manufacture of circuit boards with line spacing of 0.3mm or more, such as membrane switch circuits and keyboard circuits. However, screen printing has fewer steps, requiring only two steps: coating and curing. The mSAP process requires steps such as lamination, exposure, development, and flash etching, resulting in a longer manufacturing time and the use of photosensitive adhesives, etching solutions, and other reagents, generating more waste and being environmentally unfriendly.

[0020] When manufacturing the copper paste layer 2, it is important to note that the actual individual circuits will be isolated copper wires. In order for each copper wire to be thickened through electroplating, these isolated copper wires must be connected to the surrounding copper wires that can conduct electricity. Therefore, a lead area 6 needs to be reserved here to temporarily keep all circuit areas 5 connected. The lead area 6 will be removed in subsequent steps.

[0021] The screen used for copper paste printing is 325 mesh, and the thickness of copper paste layer 2 is 15~20um. The forward squeegee speed for copper paste printing is 260mm / s, and the reverse squeegee speed is 300mm / s.

[0022] The amount of ink applied in screen printing is determined by the mesh count. A higher mesh count results in smaller apertures and less ink, which can compromise line integrity. Conversely, a lower mesh count results in larger apertures and more ink, which can cause ink diffusion and compromise line spacing accuracy. Therefore, experience suggests that a 325-mesh screen is preferable, and a copper paste layer thickness of 15-20µm is ideal. During the coating process, forward motion ensures the low-temperature curing copper paste covers the entire line area, allowing time for it to pass through the mesh. Reverse motion further ensures the paste passes through the mesh, so the forward motion speed is generally lower than the desired speed.

[0023] S3, copper plating of circuit: copper plating layer 3 is electroplated on the surface of copper paste layer 2, and copper paste layer 2 and copper plating layer 3 constitute the circuit.

[0024] The copper paste layer 2 here will also serve as the seed layer for copper plating. Because the copper content in the copper paste layer 2 is relatively low, its resistance will be relatively high, resulting in a large impedance when used alone as a circuit material. Since pure copper has a low resistivity, pure copper needs to be plated onto the surface of the copper paste layer 2 to obtain a low-impedance circuit. After energizing, the entire surface of the copper paste layer 2 becomes negatively charged, attracting copper ions in the plating solution to undergo an electrochemical reaction, reducing them to elemental copper, which then adheres to the surface of the copper paste layer 2 (including circuit area 5 and lead area 6). The surface of the elemental copper will also acquire a negative charge and continue to react with the copper ions, ultimately forming the circuit. The copper coverage here extends beyond the upward surface of the copper paste layer 2 to include its sides. Therefore, while increasing the thickness, the increase in linewidth must also be considered. Consequently, the printing area of ​​the copper paste layer 2 is 10µm smaller than the circuit design pattern, and the thickness of the copper plating layer 3 is generally 10~15µm.

[0025] S4, Laser Leads: The copper paste layer and copper plating layer of lead area 6 are removed together by laser cutting, leaving the circuit layer within the circuit design pattern area.

[0026] Because electroplating inevitably results in copper growth around lead area 6, leaving this area inside the product would cause a short circuit. Therefore, it needs to be removed using a laser. Laser cutting allows for precise control of the cutting thickness, ensuring that excess material in lead area 6 is removed while the substrate 1 remains relatively intact.

[0027] S5. Lamination and lamination: An insulating film is bonded to the surface of the copper-plated layer 3 and then cured to obtain the insulating layer 4.

[0028] The insulating film acts as an encapsulator, filling the gaps between circuit lines and isolating them to prevent short circuits. If the product is a multilayer board, insulating layer 4 can serve as a new substrate, upon which new circuit layers can be fabricated. This process can be used in FPCs as well as on ordinary PCBs.

[0029] This method is applicable to the manufacturing of circuit boards with line spacing of 0.3mm or more. It can significantly reduce the circuit manufacturing cycle, eliminate the use of photosensitive adhesive and etching solution, reduce waste generation, and is more environmentally friendly.

[0030] The above descriptions are merely some embodiments of the present invention. Those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A method for manufacturing wide-spacing lines, characterized in that... The steps include: S1. Cutting: Cutting large-size copper-clad laminates into substrates of the required production specifications; S2, Copper paste printing: Using screen printing, low-temperature curing copper paste is printed on the surface of the substrate according to a preset printing range. The preset printing range includes several circuit areas and several lead areas. The circuit areas correspond to the positions of the actual circuits. The lead areas are used to connect isolated circuit areas with adjacent circuit areas. The low-temperature curing copper paste is baked and cured to obtain a copper paste layer. S3. Copper plating of circuit: Electroplating a copper plating layer on the surface of the copper paste layer, wherein the copper paste layer and the copper plating layer constitute a circuit layer; S4, Laser Leads: The copper paste layer and copper plating layer in the lead area are removed together by laser cutting, leaving the circuit layer within the circuit design pattern area; S5. Coating and lamination: An insulating film is bonded to the surface of the copper-plated layer and then cured to obtain an insulating layer.

2. The method for manufacturing wide-spacing lines according to claim 1, characterized in that: The low-temperature curing copper paste was provided by Suzhou Jinyi New Material Technology Co., Ltd., with a curing temperature of 150~180℃ and a curing time of 50~80min.

3. The method for manufacturing wide-spacing lines according to claim 2, characterized in that: The copper paste printing uses a 325-mesh screen, and the thickness of the copper paste layer is 15~20um.

4. The method for manufacturing wide-spacing lines according to claim 1, characterized in that: The forward squeegee speed for copper paste printing is 260 mm / s, and the reverse squeegee speed is 300 mm / s.

5. The method for manufacturing wide-spacing lines according to claim 1, characterized in that: The thickness of the copper plating layer is 10~15um, and the printing range of the copper paste layer is 10um smaller than the circuit design pattern.

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