Double-sided circuit board conduction structure and double-sided circuit board

Abstract

The utility model discloses a double-sided circuit board conduction structure and a double-sided circuit board, the double-sided circuit board conduction structure comprises an upper circuit layer and a lower circuit layer which are respectively pasted on two sides of an insulating base material layer, and conduction blind holes are respectively formed at positions, which need to be conducted, of the upper circuit layer and the lower circuit layer on the two sides of the insulating base material layer. The upper circuit layer and the lower circuit layer are conducted in a welding mode. According to the double-sided circuit board conduction structure and the double-sided circuit board, conduction is realized by welding at the conduction blind holes, electroplating is not needed, and special equipment for fine exposure and development and the like is not needed; special chemical products such as a dry film developing solution and a film stripping solution are not needed, so that the cost is reduced and the pollution is reduced; and the conduction blind hole at the conduction position can be as small as 0.4 mm, so that the precision is high.

Description

Technical Field

[0001] The utility model relates to an LED integrated circuit board, in particular to a double-sided circuit board conduction structure and a double-sided circuit board. Background Art

[0002] Double-sided circuit boards generally require the two layers of circuits to be connected to form an electrical connection when in use. The existing connection methods are as follows:

[0003] The first method is the plug-hole conduction method, which is commonly known as false double-sided in the industry. Figure 1a As shown, the manufacturing process is roughly as follows: 1. Cut the sheet material as required; 2. Use CNC to drill positioning holes and vias; 3. Use ordinary silk-screen anti-etching circuit oil or photosensitive circuit oil to make circuit patterns; 4. Etching; 5. Remove the circuit ink used in the third process; 6. Clean the circuit board; 7. Apply solder mask ink; 8. Use carbon oil or silver oil or copper paste or a mixture of the above conductive inks to plug or penetrate the via holes to make the two circuit layers conductive; 9. Print characters and process pad protection; 10. Test the circuit board application.

[0004] The cost of circuit boards produced by the plug-hole method is low, but the resistance at the via hole is large, and the conductive ink at the via hole is easy to fall off. Fine circuits cannot be produced using this method, so it is not widely used.

[0005] The second method is solder paste conduction method, such as Figure 1b As shown in the figure, the 1-7 steps in its manufacturing process are consistent with the first plug-hole conduction method; the 8th step is: printing characters and processing pad protection; 9. Testing; 10. Using the circuit board. When using the circuit board, solder paste is printed on the conduction hole with a steel screen at the same time. After reflow soldering together with the electronic components, the two circuit layers are connected by soldering.

[0006] Therefore, the solder paste method is commonly used on thin boards due to tin's ability to climb high, particularly in today's flexible LED strips. Its advantages include lower production costs and the lack of electroplating. While it can be produced using conventional silk-screen anti-etching circuit paint or circular die-cutting processes, it is limited by factors such as the solder paste's ability to climb high, the flatness and cleanliness of the soldering area, the area of ​​the soldered surface, and soldering temperature. This can lead to quality issues such as false solder joints and pad breakage. Furthermore, soldering requires a large soldering surface for optimal adhesion, so this method cannot be used on delicate circuit boards or those thicker than 0.3mm.

[0007] The third method is electroplating conduction method, such as Figure 1cAs shown in the figure, the production process is as follows: 1. Cut the sheet material as required; 2. Use CNC to drill positioning holes and vias; 3. Electroplating (first make the two circuit layers conductive as required); 4. Use special dry film and exposure and development process to make the circuit layer pattern; 5. Etching; 6. Remove the special dry film used in the fourth process; 7. Clean the circuit board; 8. Apply solder mask ink or make solder mask lamination; 9. Print characters and process pad protection layer. 10. Testing; 11. Circuit board application.

[0008] The existing technology for through-hole fabrication in circuit boards is characterized by the following: the plug-via method has a minimum hole diameter of 1.0mm or larger, the solder paste (soldering) method has a minimum hole diameter of 0.8mm or larger, and the electroplating method can achieve a minimum hole diameter of 0.15mm. Therefore, this method is mostly used to produce precision circuit boards, but it requires supporting electroplating equipment, exposure and development equipment, and dry film lamination equipment, resulting in high equipment investment. Furthermore, it uses a large number of chemical products, such as dry film developer solutions, specialized stripping solutions, and electroplating solutions, resulting in high material costs and significant wastewater, solid waste, and exhaust gas treatment costs.

[0009] Therefore, it is necessary to solve the above technical problems. Summary of the Invention

[0010] In response to the above technical problems, the utility model provides a double-sided circuit board conductive structure and a double-sided circuit board. The conductive blind holes at the conductive part can be as small as 0.4mm with high precision; no electroplating is required, and no special equipment such as fine exposure and development is required; no special chemical products such as dry film developer and stripper are required, thereby reducing costs and pollution.

[0011] In order to achieve the above purpose, the technical solution of the utility model is:

[0012] A double-sided circuit board conductive structure includes an upper circuit layer and a lower circuit layer respectively adhered to the two sides of an insulating substrate layer. Conductive blind holes are formed on both sides of the insulating substrate layer at the positions where the upper circuit layer and the lower circuit layer need to be conductive. The upper circuit layer and the lower circuit layer are conductively connected by welding.

[0013] The double-sided circuit board conductive structure is connected by welding at the conductive blind holes, without the need for electroplating, and does not require special equipment such as fine exposure and development; it does not require special chemical products such as dry film developer and stripper, thus reducing costs and pollution; the conductive blind holes at the conductive part can be as small as 0.4mm, with high precision.

[0014] In a further optimized solution, adhesive is provided on both sides of the insulating substrate layer. The upper circuit layer and the lower circuit layer are respectively adhered by the adhesive of the insulating substrate layer, which makes the processing simple and convenient.

[0015] According to a further optimization solution, the upper circuit layer and the lower circuit layer are connected to each other by laser welding, ultrasonic welding or cold welding.

[0016] In a further optimization solution, the insulating substrate layer is made of polyimide, polyester, or fiberglass. Different insulating substrate materials can be selected based on different needs. Since the double-sided circuit board's conductive structure does not require electroplating and uses welding, a polyester substrate can be used, further reducing costs.

[0017] In a further optimized solution, the insulating substrate layer is provided continuously or discontinuously along the length direction. The insulating substrate layer can be used continuously in an unlimited length and produced in rolls to better achieve automated production; the discontinuous arrangement can form a sheet for use.

[0018] In a further optimization solution, the upper and lower circuit layers are each formed of metal foil, and may be a combination of copper / copper, copper / aluminum, copper / copper-aluminum alloy, aluminum / aluminum, aluminum / copper, or copper-aluminum alloy / copper-aluminum alloy. The upper and lower circuit layers can be formed of aluminum foil or copper foil in different combinations to meet different needs and save material costs.

[0019] A double-sided circuit board comprises any of the above-mentioned double-sided circuit board conductive structures.

[0020] In a further optimization solution, the outer sides of the upper and lower circuit layers are respectively coated with solder mask ink or solder mask protective film. Coating the outer sides of the upper and lower circuit layers with solder mask ink or solder mask protective film can better protect the double-sided circuit board and enhance its strength.

[0021] The double-sided circuit board has a high conductive structure and high precision. The blind hole position of the conductive hole can be as small as 0.4mm, and the laser welding point can be as fine as 0.10mm.

[0022] 2. The double-sided circuit board conductive structure and the double-sided circuit board are conductive by welding at the conductive blind holes, without the need for electroplating, and without the need for special equipment such as fine exposure and development;

[0023] 3. The double-sided circuit board conductive structure and double-sided circuit board do not require expensive chemical products such as electroplating solution, dry film developer and stripper, thus reducing costs and pollution.

[0024] 4. The double-sided circuit board conductive structure and the double-sided circuit board are not affected by the working capacity of special equipment such as electroplating, exposure and development. They can be processed continuously in unlimited length and the whole roll production can better realize automated production. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1a This is a schematic diagram of the plug-hole conduction method structure of the double-sided circuit board conduction structure in the prior art;

[0026] Figure 1b This is a schematic diagram of the solder paste conduction method structure of the double-sided circuit board conduction structure in the prior art;

[0027] Figure 1c This is a schematic diagram of the electroplating conduction method structure of a double-sided circuit board conduction structure in the prior art;

[0028] Figure 2 It is a structural diagram of a double-sided circuit board conductive structure and a specific embodiment of the double-sided circuit board of the utility model;

[0029] Figure 3a This is a schematic diagram of the double-sided circuit board of the utility model after the insulating base material layer with adhesive on both sides is processed with through holes;

[0030] Figure 3b This is a schematic diagram of the insulating substrate layer laminating the upper circuit layer and the lower circuit layer of the double-sided circuit board of the utility model;

[0031] Figure 3c It is a schematic diagram of conducting blind vias formed on both sides of the insulating base material layer of the double-sided circuit board of the present invention;

[0032] Figure 3d This is a schematic diagram of the upper circuit layer and the lower circuit layer of the double-sided circuit board of the utility model after laser welding.

[0033] In the figure: upper circuit layer 1, insulating substrate layer 2, lower circuit layer 3, conductive blind via 4, solder mask 5, laser welding point 6. DETAILED DESCRIPTION

[0034] The present invention will be described in further detail below with reference to the embodiments in the accompanying drawings.

[0035] like Figure 2 and Figures 3a to 3d As shown, a specific embodiment of the double-sided circuit board conductive structure and the double-sided circuit board of the present invention.

[0036] like Figure 2 As shown, the double-sided circuit board conductive structure of this embodiment includes an upper circuit layer 1 and a lower circuit layer 3 respectively adhered to the two sides of the insulating substrate layer 2, and conductive blind holes 4 are respectively formed at the positions where the circuit layer 1 and the lower circuit layer 3 need to be conductive on both sides of the insulating substrate layer 2, and the upper circuit layer 1 and the lower circuit layer 3 are conductively connected by welding.

[0037] The double-sided circuit board conductive structure is connected by welding at the conductive blind holes, without the need for electroplating, and does not require special equipment such as fine exposure and development; it does not require special chemical products such as dry film developer and stripper, thus reducing costs and pollution; the conductive blind holes at the conductive part can be as small as 0.4mm, with high precision.

[0038] like Figure 3a As shown, adhesive is applied to both sides of the insulating substrate layer 2. The upper circuit layer and the lower circuit layer are attached to each other through the adhesive of the insulating substrate layer, which makes the processing simple and convenient.

[0039] The insulating substrate layer 2 is made of polyimide, polyester, or fiberglass. Different insulating substrate materials can be selected based on different needs. Since the double-sided circuit board's conductive structure doesn't require electroplating and uses welding, a polyester substrate can be used, further saving costs.

[0040] The insulating substrate layer 2 is continuously provided along the length direction. The insulating substrate layer can be used continuously in an unlimited length and can be produced in a whole roll to better realize automated production.

[0041] The upper circuit layer 1 and the lower circuit layer 3 are each made of metal foil, and can be one of a combination of copper / copper, copper / aluminum, copper / copper-aluminum alloy, aluminum / aluminum, aluminum / copper, or copper-aluminum alloy / copper-aluminum alloy. The upper and lower circuit layers can be made of aluminum foil or copper foil in different combinations to meet different needs and save material costs.

[0042] like Figure 3d As shown, the upper circuit layer 1 and the lower circuit layer 3 are connected by laser welding to form laser welding points 6. The upper circuit layer and the lower circuit layer can also be connected by ultrasonic welding or cold welding.

[0043] The utility model also discloses a double-sided circuit board, such as Figure 2 As shown, the double-sided circuit board includes the aforementioned double-sided circuit board conductive structure; solder mask 5 is applied to the outer sides of the upper circuit layer 1 and the lower circuit layer 3, respectively, and component pads can be arranged between the solder mask 5. Applying solder mask to the outer sides of the upper and lower circuit layers can better protect the double-sided circuit board and enhance its strength.

[0044] The specific process steps of the double-sided circuit board are as follows:

[0045] 1. Select a 25 micron thick polyimide (PI) insulating substrate layer with a total thickness of 75 microns and 25 micron adhesive on both sides, in a roll of 250 mm wide and 100 m long.

[0046] 2. Use a roll-to-roll CNC drilling machine to process through holes according to the design data (such as Figure 3a shown);

[0047] 3. Use a double-sided laminating machine to laminate 35 micron copper foil on both sides of the insulating substrate layer completed in step 2. The laminating temperature is 90°C and the line speed is 3 meters per minute (such as Figure 3b and Figure 3c shown);

[0048] 4. Curing the double-sided copper-clad insulating substrate layer from step 3 at 150°C for 60 minutes;

[0049] 5. Use a 600-watt laser welding machine to weld the holes in the coordinates of the holes processed in step 2 according to the design data to achieve the desired conduction of the copper foil on both sides (such as Figure 3d shown);

[0050] 6. Use an automatic continuous screen printer to take acid-resistant etching circuit ink and print the upper and lower circuit layer patterns on the substrate completed in step 5 according to the design orientation;

[0051] 7. Use a common acid etching machine to etch the substrate in step 6 and remove the circuit ink to obtain a double-sided circuit substrate;

[0052] 8. Clean the double-sided circuit substrate after etching and ink removal in a cleaning machine;

[0053] 9. Place the polyimide (PI) protective film with pre-processed pad windows on the cleaned double-sided circuit substrate according to the designed positioning holes, and attach the protective films of the upper and lower circuit layers. Curing at 150°C for 60 minutes.

[0054] 10. Use automatic continuous printing machine to print characters, and use OSP equipment to do pad protection treatment;

[0055] 11. Use needle test frame to test circuit board;

[0056] 12. Process the above circuit boards, inspect and package them.

[0057] The double-sided circuit board conductive structure and the double-sided circuit board are conductive by welding at the conductive blind holes, without the need for electroplating, and do not require special equipment such as fine exposure and development. Special chemical products such as dry film developer and stripper are not required, which reduces costs and pollution. The conductive blind holes at the conductive part can be as small as 0.4mm, with high precision. The double-sided circuit board is not affected by the working capacity of special equipment such as electroplating, exposure and development, and can be continuously processed in unlimited length, and the whole roll production can better realize automated production.

[0058] In summary, the present invention, as described in the specification and illustrations, has been manufactured into actual samples and tested multiple times. The test results demonstrate that the present invention can achieve its intended purpose and its practicality is unquestionable. The above embodiments are merely intended to facilitate the description of the present invention and are not intended to be formally limiting. Any equivalent embodiments that are partially modified or modified by a person skilled in the art, without departing from the scope of the present invention and similar features, utilizing the technical features disclosed in the present invention, fall within the scope of protection of the present invention.

Claims

1. A double-sided circuit board conductive structure, characterized by: The invention comprises an upper circuit layer (1) and a lower circuit layer (3) respectively adhered to both sides of an insulating substrate layer (2), wherein conductive blind holes (4) are respectively formed at positions on both sides of the insulating substrate layer (2) where the upper circuit layer (1) and the lower circuit layer (3) need to be conductive, and the upper circuit layer (1) and the lower circuit layer (3) are conductively connected by welding.

2. The double-sided circuit board conductive structure according to claim 1, wherein: Adhesive is provided on both sides of the insulating substrate layer (2).

3. The double-sided circuit board conductive structure according to claim 1, wherein: The upper circuit layer (1) and the lower circuit layer (3) are connected to each other by laser welding, ultrasonic welding or cold welding.

4. The double-sided circuit board conductive structure according to claim 1, wherein: The material of the insulating substrate layer (2) is polyimide or polyester material or glass fiber.

5. The double-sided circuit board conductive structure according to claim 1, wherein: The insulating substrate layer (2) is arranged continuously or discontinuously along the length direction.

6. The double-sided circuit board conductive structure according to claim 1, wherein: The upper circuit layer (1) and the lower circuit layer (3) are metal foils, respectively, which are a combination of copper / copper, copper / aluminum, copper / copper-aluminum alloy, aluminum / aluminum, aluminum / copper, copper-aluminum alloy / copper-aluminum alloy.

7. A double-sided circuit board, characterized in that: The double-sided circuit board conductive structure comprises any one of claims 1 to 6.

8. The double-sided circuit board according to claim 7, wherein: The outer sides of the upper circuit layer (1) and the lower circuit layer (3) are respectively coated with solder resist ink or laminated with a solder resist protective film (5).

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