Manufacturing method of long resistance wire, printed circuit board and manufacturing method of printed circuit board

Abstract

The invention discloses a manufacturing method of a long resistance wire, a printed circuit board and a manufacturing method of the printed circuit board. The manufacturing method of the long resistance wire comprises the steps that a plurality of wire passing holes penetrating through copper foil layers located on the two outermost sides of a machining plate are machined in preset positions of the machining plate; carrying out circuit manufacturing on the processing board so as to respectively manufacture conduction connecting pieces in the plurality of wire passing holes and respectively manufacture circuit patterns on the two copper foil layers; the circuit pattern on each copper foil layer comprises a plurality of short resistance line segments, and the plurality of short resistance line segments on the two copper foil layers are connected in series through a plurality of conduction connecting pieces to form a long resistance line; the sectional area of the conduction connecting piece is twice larger than that of the short resistance line segment; and performing AOI inspection and correction on the circuit pattern. The manufacturing method of the long resistance wire is simple, reasonable and easy to operate, the obtained long resistance wire is high in resistance value precision on the basis of meeting the specific resistance value requirement, and the processing requirement of a printed circuit board is met.

Description

Technical Field

[0001] The present invention relates to the technical field of printed circuit boards, and in particular, to a manufacturing method of a long resistance wire, a printed circuit board and a manufacturing method thereof. Background Art

[0002] Currently, in the processing of printed circuit boards, there are the following difficulties in the manufacturing of resistance wires: to meet the resistance value requirements, the length of the resistance wire is generally designed to be very long, such as generally between 1 meter and several meters, which makes the processing of the long resistance wire very difficult and difficult to produce and implement.

[0003] In view of this, the present invention is specifically proposed. Summary of the Invention

[0004] In order to overcome the above defects, the present invention provides a manufacturing method of a long resistance wire, a printed circuit board and a manufacturing method thereof. The manufacturing method of the long resistance wire is simple, reasonable, easy to operate and implement, and on the basis of well meeting the specific resistance value requirements, the resistance value accuracy of the obtained long resistance wire is very high, which well meets the processing requirements of the printed circuit board.

[0005] The technical solution adopted by the present invention to solve its technical problems is: a manufacturing method of a long resistance wire, including:

[0006] Providing a processing board, both outermost layers of the processing board opposite to each other are copper foil layers;

[0007] Processing tool holes at preset positions of the processing board, the tool holes including a plurality of wire passing holes penetrating through the two copper foil layers;

[0008] Performing circuit manufacturing on the processing board to respectively manufacture conduction connectors in a plurality of the wire passing holes and circuit patterns on the two copper foil layers; the circuit patterns on each copper foil layer each include a plurality of short resistance line segments, and the plurality of short resistance line segments on the two copper foil layers are also connected in series through a plurality of the conduction connectors to form a long resistance wire; in addition, the cross-sectional area of the conduction connector is more than twice the cross-sectional area of the short resistance line segment;

[0009] Performing AOI inspection and correction on the circuit patterns.

[0010] As a further improvement of the present invention, after the processing board is successively subjected to electroless copper plating, full-board electroplated copper layer, pre-treatment before film lamination, coating of anti-plating photosensitive film, exposure, development, pattern electroplated copper layer, electroplated tin layer, film stripping, alkaline etching of copper, and removal of the tin plating layer, the conduction connectors and the circuit patterns are manufactured.

[0011] As a further improvement of the present invention, the wire passing hole is a cylindrical hole, and the conduction connecting member is a cylindrical ring-shaped copper layer formed on the inner peripheral surface of the wire passing hole; correspondingly, the cross-sectional area of the conduction connecting member satisfies the following formula: S1 = π×D×h1; where D is the diameter of the wire passing hole, and h1 is the copper thickness of the conduction connecting member;

[0012] The cross-sectional area of the short resistance wire segment satisfies the following formula: S2 = W×h2; where W is the line width of the short resistance wire segment, and h2 is the copper thickness of the short resistance wire segment.

[0013] As a further improvement of the present invention, the diameter of the wire passing hole is 0.4 - 0.6 mm; the copper thickness of the conduction connecting member is 0.02 - 0.03 mm;

[0014] The line width of the short resistance wire segment is 0.3 - 0.5 mm, and the copper thickness is 0.04 - 0.06 mm.

[0015] As a further improvement of the present invention, the line length of the short resistance wire segment is 90 - 120 mm, and the total number of the short resistance wire segments located on the two copper foil layers is 30 - 40.

[0016] As a further improvement of the present invention, the processing parameters of the above-mentioned full-board electroplated copper layer are: the temperature of the copper plating solution is 20 - 35 °C, the concentration of copper sulfate in the copper plating solution is 50 - 100 g / L, the concentration of sulfuric acid is 150 - 225 g / L, the chloride ion content is 30 - 80 PPM, and the concentration of the brightening agent is 4 - 10 mL / L; the current density is 1.2 - 1.8 A / dm 2 , and the electroplating time is 18 - 25 min.

[0017] As a further improvement of the present invention, the processing parameters of the above-mentioned pattern electroplated copper layer are: the temperature of the copper plating solution is 20 - 30 °C, the concentration of copper sulfate in the copper plating solution is 60 - 90 g / L, the concentration of sulfuric acid is 150 - 225 g / L, the chloride ion content is 30 - 80 PPM, and the concentration of the brightening agent is 6 - 10 mL / L; the current density is 1.5 - 2.2 A / dm 2 , and the electroplating time is 50 - 65 min.

[0018] As a further improvement of the present invention, when performing the above-mentioned film stripping, alkaline copper etching, and tin plating layer removal processes, the pH value of the chemical solution used is 8.4 - 8.8, the temperature is 45 - 55 °C, the spraying pressure is 0.8 - 3 kg / cm 2 , and the board transfer speed is 3 - 5 m / min, and the etching factor is not less than 2.6.

[0019] The present invention also provides a method for manufacturing a printed circuit board, including:

[0020] Provide an intermediate board, and the intermediate board is provided with a long resistance wire manufactured by using the manufacturing method of the long resistance wire as described in the present invention;

[0021] After sequentially performing conventional resin plugging of holes, solder mask, printing of characters, hot air leveling, shaping, cleaning, and electrical testing on the intermediate board, a printed circuit board is manufactured.

[0022] The present invention also provides a printed circuit board manufactured by using the manufacturing method of the printed circuit board as described in the present invention.

[0023] The beneficial effects of the present invention are as follows: 1) By manufacturing a plurality of short resistance line segments on the board, and connecting the short resistance line segments in series through conduction connectors formed in via holes to form a long resistance wire with a very long wire length, the processing requirements of the long resistance wire with a specific resistance value are well met. In addition, when manufacturing the long resistance wire, the cross-sectional area of the conduction connector is preferably designed to be more than twice the cross-sectional area of the short resistance line segment, so as to achieve that the overcurrent capacity of the conduction connector is much greater than the overcurrent capacity of the short resistance line segment, thereby well ensuring that the influence of the resistance value of the conduction connector on the resistance value of the short resistance line segment can be ignored, and greatly improving the resistance value accuracy of the long resistance wire. 2) The manufacturing method of the long resistance wire provided by the present invention is simple, reasonable, easy to implement in production, and the finished product yield of the obtained intermediate board and printed circuit board is high and the quality is good. Description of the Drawings

[0024] Figure 1 It is a process flow chart of the manufacturing method of the long resistance wire in Embodiment 1 of the present invention;

[0025] Figure 2 It is a schematic cross-sectional structure diagram of the processing board described in the present invention;

[0026] Figure 3 It is a schematic cross-sectional structure diagram of the intermediate board A described in the present invention;

[0027] Figure 4 It is a schematic cross-sectional structure diagram of the intermediate board B described in the present invention;

[0028] Figure 5 It is a schematic cross-sectional structure diagram of the intermediate board obtained after completing the entire circuit manufacturing on the processing board described in the present invention;

[0029] Figure 6 It is Figure 5 a schematic top view structure diagram of the intermediate board;

[0030] Figure 7 It is Figure 6 an enlarged structure diagram of part A shown in

[0031] Figure 8 This is the process flow chart of the manufacturing method of the printed circuit board described in Embodiment 2 of the present invention.

[0032] The following is an explanation with reference to the accompanying drawings:

[0033] 1. Processing board; 10. Copper foil layer; 11. Insulating substrate; 12. Through-hole;

[0034] 13. Via hole; 14. Outer copper foil; 20. Conductive connection member; 21. Short resistance line segment; 22. Other circuits; 23. Long resistance line; 24. Conductive connection member A; 25. Copper plating layer. Detailed implementation manners

[0035] The following is a detailed description of the preferred embodiments of the present invention with reference to the accompanying drawings.

[0036] Embodiment 1:

[0037] Please refer to the attached Figure 1 to the attached Figure 7 As shown, Embodiment 1 of the present invention provides a manufacturing method for a long resistance line, including the following manufacturing steps:

[0038] S1. Provide a processing board 1, and both outermost layers of the processing board 1 opposite to each other are copper foil layers 10.

[0039] Specifically, for the convenience of describing the manufacturing principle of the manufacturing method of the long resistance line described in this application, in Embodiment 1, the processing board 1 is taken as an example of a double-sided copper clad laminate for description. However, it can be understood that the processing board 1 is not limited thereto. According to the processing requirements of the product, the processing board 1 can also adopt a working board and other structures that have completed the inner layer circuit manufacturing and double-sided lamination and build-up operations.

[0040] When the processing board 1 adopts a double-sided copper clad laminate, its specific structure is: see the attached Figure 2 As shown, the processing board 1 is provided with an insulating substrate 11 and two copper foil layers 10 respectively fixedly disposed on the front and back surfaces of the insulating substrate 11. The insulating substrate 11 can adopt but is not limited to semi-cured sheet materials, and in Embodiment 1, no limitation is imposed on the thickness of the insulating substrate 11 and the copper foil layer 10, which is determined according to the product design requirements.

[0041] S2. First, perform a baking operation on the processing board 1 to age the incompletely cured epoxy resin in the insulating substrate 11 and simultaneously release the stress in the insulating substrate 11; then, process tool holes at preset positions on the processing board 1 by mechanical drilling and / or laser drilling. The tool holes include several through-holes 12, a plurality of via holes 13, and a plurality of mounting holes. Please refer to the attached Figure 3 As shown, but it can be understood that because the attached Figure 3As a structural schematic diagram, the number of wire passing holes 12 and via holes 13 thereon is not the actual number of the product; a plurality of the wire passing holes 12 and a plurality of the via holes 13 are all cylindrical hole structures, and each of the wire passing holes 12 respectively penetrates through two of the copper foil layers 10 for forming conduction connectors 20 in a subsequent process; each of the via holes 13 also respectively penetrates through two of the copper foil layers 10 for forming conduction connector A24 in a subsequent process; the mounting holes are for mounting electronic components.

[0042] In addition, for the convenience of description, in this Embodiment 1, the board obtained after the drilling process of the processing board 1 is defined as "intermediate board A".

[0043] S3. Perform circuit manufacturing on the processed board 1 after the drilling process (i.e., perform circuit manufacturing on the intermediate board A) to respectively manufacture conduction connectors 20 in a plurality of the wire passing holes 12, manufacture conduction connector A24 in a plurality of the via holes 13, and manufacture circuit patterns on the two copper foil layers 10 respectively; the circuit patterns on each of the copper foil layers 10 each include a plurality of short resistor segments 21 and other circuits 22, and a plurality of the short resistor segments 21 on the two copper foil layers 10 are also connected in series through a plurality of the conduction connectors 20 to form a long resistor line 23, and the other circuits 22 on the two copper foil layers 10 are also connected and communicated through the conduction connector A24. Reference can be made to Attachment Figure 5 to Attachment Figure 7 as shown; in addition, the cross-sectional area of the conduction connector 20 is also designed to be more than twice the cross-sectional area of the short resistor segment 21, so as to achieve that the current-carrying capacity of the conduction connector 20 is much greater than the current-carrying capacity of the short resistor segment 21, thereby ensuring that the influence of the resistance value of the conduction connector 20 on the resistance value of the short resistor segment 21 can be ignored, and ensuring the improvement of the overall resistance value accuracy of the obtained long resistor line. Supplementary description: In Attachment Figure 6 and Attachment Figure 7 , the short resistor segment 21 indicated by a "solid line" can be understood as the short resistor segment 21 arranged on the front surface of the processing board 1, and the short resistor segment 21 indicated by a "dashed line" can be understood as the short resistor segment 21 arranged on the back surface of the processing board 1.

[0044] Specifically, the circuit manufacturing method preferably implemented for the processing board 1 in this Embodiment 1 is: sequentially perform electroless copper plating, full-board electroplated copper layer, pre-treatment before film lamination, coating of anti-plating photosensitive film, exposure, development, pattern electroplated copper layer, electroplated tin layer, film stripping, alkaline etching of copper, and removal of the tin plating layer on the processing board 1 to manufacture the conduction connector 20, the conduction connector A24, and the circuit pattern.

[0045] The above method for manufacturing the circuit is further described as follows:

[0046] ① Chemical copper deposition: A seed copper layer with a set thickness is deposited on the inner circumferential surfaces of the via holes 12 and the through holes 13 by using the chemical copper deposition process commonly used in the field of circuit board processing;

[0047] ② Full-panel electroplated copper layer: A thickened copper layer with a set thickness (such as 8 μm) is electroplated on the seed copper layer and the two copper foil layers 10 respectively by using an electroplating process (which can preferably be a vertical electroplating process) to protect the seed copper layer from being oxidized or corroded; At this time, the seed copper layer and the thickened copper layer on the inner circumferential surface of the via hole 12 together constitute the conduction connector 20, the seed copper layer and the thickened copper layer on the inner circumferential surface of the through hole 13 together constitute the conduction connector A24, and the copper foil layer 10 and the thickened copper layer thereon together constitute the outer copper foil 14 (the difference between it and the copper foil layer 10 lies in the thickness); reference can be made to the attached Figure 4 shown. It can be understood that the conduction connector 20 and the conduction connector A24 are respectively conductively connected to the two outer copper foils 14.

[0048] Further, based on the shape of the via hole 12, the conduction connector 20 is a cylindrical ring-shaped copper layer. And to meet the design requirement that the conduction connector 20 has a large over-current capacity, the following optimal control design is also made for the conduction connector 20 in this embodiment: The cross-sectional area of the conduction connector 20 satisfies the following formula: S1 = π×D×h1; where D is the diameter of the via hole 12, which can be specifically designed to be 0.4 - 0.6 mm; h1 is the copper thickness of the conduction connector 20, which can be specifically designed to be 0.02 - 0.03 mm.

[0049] As can be seen from the above, the copper thickness of the conduction connector 20 is much smaller than the diameter (radius) of the via hole 12. Therefore, the "cross-sectional area of the conduction connector 20" defined above is actually an assumed area, which can achieve convenient calculation and will not have an adverse impact on the design requirements.

[0050] Further, based on the shape of the through hole 13, the conduction connector A24 is also a cylindrical ring-shaped copper layer.

[0051] Further, when performing the full-panel electroplated copper layer operation in this embodiment, the preferred processing parameters are: the temperature of the copper plating solution is 20 - 35 °C, the concentration of copper sulfate in the copper plating solution is 50 - 100 g / L, the concentration of sulfuric acid is 150 - 225 g / L, the chloride ion content is 30 - 80 PPM, the concentration of the brightener (PC-667) is 4 - 10 mL / L; the current density is 1.2 - 1.8 A / dm 2 , and the electroplating time is 18 - 25 min.

[0052] In addition, for the convenience of description, in this Embodiment 1, the board obtained after the full-board electroplated copper layer operation on the processing board 1 is defined as the "intermediate board B", and the structure of the intermediate board B can be referred to in the attached Figure 4 shown.

[0053] ③ Pretreatment before film lamination and coating of anti-plating photosensitive film: "Pretreatment before film lamination" is to perform roughening treatment (or micro-etching or grinding treatment), cleaning, and drying treatment on the intermediate board B in sequence to enhance the bonding force between the anti-plating photosensitive dry film and the outer copper foil 14 in the subsequent process. "Coating of anti-plating photosensitive film" is to attach the anti-plating photosensitive dry film to the outer copper foil 14. Further, the film lamination operation can be implemented by a vacuum film laminator, and its film lamination flatness is high, which can further enhance the bonding force between the anti-plating photosensitive dry film and the outer copper foil 14.

[0054] ④ Exposure and development: "Exposure" is to expose some areas of the anti-plating photosensitive dry film according to the operation data; "Development" is to remove the unexposed areas of the anti-plating photosensitive dry film.

[0055] ⑤ Pattern electroplating of copper layer and electroplating of tin layer: "Pattern electroplating of copper layer" is to electroplate a copper layer 25 with a set thickness (such as 25 μm) on the exposed areas of the outer copper foil 14 by using the pattern electroplating process. Among them, the exposed areas of the outer copper foil 14 refer to the areas on the outer copper foil 14 that are exposed outside the anti-plating photosensitive dry film. "Electroplating of tin layer" is to electroplate a tin layer with a set thickness (such as about 5 - 8 μm) on the copper layer 25 by using the pattern electroplating process.

[0056] Further, when performing the pattern electroplating of copper layer operation in this embodiment, the preferably adopted processing parameters are: the temperature of the copper plating solution is 20 - 30 °C, the concentration of copper sulfate in the copper plating solution is 60 - 90 g / L, the concentration of sulfuric acid is 150 - 225 g / L, the chloride ion content is 30 - 80 PPM, and the concentration of the brightener (CB-203A) is 6 - 10 mL / L; the current density is 1.5 - 2.2 A / dm 2 , and the electroplating time is 50 - 65 min.

[0057] ⑥Film stripping, alkaline copper etching, and tin plating layer removal: "Film stripping" is to remove the anti-plating photosensitive dry film using a strong alkaline solution. "Alkaline copper etching" is to remove the exposed area A of the outer copper foil 14 using an alkaline etching solution, where the exposed area A of the outer copper foil 14 refers to the area on the outer copper foil 14 that is exposed outside the tin plating layer. "Removing the tin plating layer" is to remove the tin plating layer using an alkaline tin stripping solution. Then the circuit pattern is obtained. It can be understood that the circuit pattern (including the short resistance line segment 21 and other circuits 22, etc.) is composed of the copper plating layer 25 and a part of the outer copper foil 14 directly below it. Please refer to the attached Figure 5 shown.

[0058] Further, when performing the above film stripping, alkaline copper etching, and tin plating layer removal processes in this embodiment, the preferred processing parameters are: the pH value of the chemical solution used is 8.4 - 8.8, the temperature is 45 - 55 °C, the spraying pressure is 0.8 - 3 kg / cm 2 , and the board transfer speed is 3 - 5 m / min, and the etching factor is not less than 2.6.

[0059] Further, from the manufacturing process of the above circuit pattern, it can be seen that the vertical cross-section of the circuit pattern is relatively regular and rectangular. Therefore, the area of the vertical cross-section of the circuit pattern is equal to the product of its line width and copper thickness. Taking the short resistance line segment 21 as an example, the cross-sectional area of the vertical cross-section of the short resistance line segment 21 satisfies the following formula: S2 = W × h2; where W is the line width of the short resistance line segment 21, and h2 is the copper thickness of the short resistance line segment 21.

[0060] Even further, to ensure that the current-carrying capacity of the conduction connector 20 is much greater than that of the short resistance line segment 21, in this embodiment, the dimensions of the short resistance line segment 21 are also optimized as follows: the line width of the short resistance line segment 21 is 0.3 - 0.5 mm, and the copper thickness is 0.04 - 0.06 mm.

[0061] Specifically: the cross-sectional area of the conduction connector 20 can be preferably designed as π × 0.5 × 0.025 = 0.039 mm 2 ; the cross-sectional area of the short resistance line segment 21 can be preferably designed as 0.3 × 0.045 = 0.0135 mm 2 .

[0062] Further, to meet the design requirements of the product resistance value, in this embodiment, the following preferred designs are also made for the short resistance line segment 21: the line length of the short resistance line segment 21 is designed to be 90 - 120 mm, and the total number of the short resistance line segments 21 on the two copper foil layers 10 is designed to be 30 - 40.

[0063] Specifically, taking the wire length of the short resistance line segment 21 as 100 mm and the quantity as 40 pieces as an example, the long resistance wire 23 can meet the design requirement of a resistance value of 5.48 Ω (calculated according to the resistivity of copper being 0.0185 Ω·mm 2 / m and the cross-sectional area of the short resistance line segment 21 being 0.0135 mm 2 .

[0064] In addition, after completing the above circuit production, the board needs to be cleaned and baked to facilitate subsequent process machining.

[0065] S4. Conduct AOI inspection and correction on the circuit pattern, that is: compare the produced circuit pattern with the design pattern through an optical scanning method, and correct the circuit pattern according to the comparison result.

[0066] In addition, for the convenience of description, in this Embodiment 1, the board obtained by successively completing drilling, circuit production, and AOI inspection on the processing board 1 is defined as an "intermediate board", and the structure of the intermediate board can be referred to in the attached Figure 5 to the attached Figure 7 .

[0067] As can be seen from the above, in the present invention, a number of the short resistance line segments are made on the board, and the short resistance line segments are connected in series through the conduction connectors formed in the via holes to form a long resistance wire with a very long wire length, thus well meeting the processing requirements of a long resistance wire with a specific resistance value. In addition, when making the long resistance wire in the present invention, the cross-sectional area of the conduction connector is preferably designed to be more than twice the cross-sectional area of the short resistance line segment, so as to make the over-current capacity of the conduction connector much greater than the over-current capacity of the short resistance line segment, thereby well ensuring that the influence of the resistance value of the conduction connector on the resistance value of the short resistance line segment can be ignored, and greatly improving the resistance value accuracy of the long resistance wire.

[0068] Embodiment 2:

[0069] Please refer to the attached Figure 8 . This Embodiment 2 provides a method for manufacturing a printed circuit board, including the following manufacturing steps:

[0070] Step 1: Provide an intermediate board, and the intermediate board is provided with a long resistance wire manufactured by using the method for manufacturing the long resistance wire described in the above Embodiment 1.

[0071] Specifically, the board obtained by successively completing drilling, circuit production, and AOI inspection on the processing board 1 in the above Embodiment 1 can be used as the intermediate board, and the specific structure can be referred to in the attached Figure 5 to the attached Figure 7 .

[0072] Step 2: After successively performing conventional resin plugging of holes, solder mask, printing of characters, hot air leveling, shaping, cleaning, electrical testing, final inspection, and packaging and processing on the intermediate board, a printed circuit board is obtained. It is understandable that the wire length of the resistance wires on the obtained printed circuit board is very long and the resistance value accuracy is very high, well meeting the market demand.

[0073] Note: The above "resin plugging of holes, solder mask, printing of characters, hot air leveling, shaping, cleaning, electrical testing, final inspection, and packaging and processing" are conventional technical means in the field of printed circuit board processing, and are briefly described as follows:

[0074] Resin plugging of holes: The via holes 12 and through holes 13 in the intermediate board are filled up by means of screen printing resin ink process.

[0075] Solder mask: A solder mask layer of a color meeting the customer's requirements is printed on the bare copper printed circuit board on which the circuit pattern has been made, and after processes such as drying, exposure, and development, the circuit pattern is covered by the solder mask layer, while the pad parts to be soldered are exposed, forming a solder mask pattern.

[0076] Printing of characters: A layer of text markings is printed on the surface of the printed circuit board to clearly show the installation positions, indications, etc. of each component.

[0077] Hot air leveling: The printed circuit board with the pad copper layer exposed is processed by a hot air leveling machine, so that a uniform and flat metal tin layer is immersed on all places where the copper layer is exposed, protecting the exposed copper layer and facilitating subsequent soldering and installation of components.

[0078] Shaping: The printed circuit board is subjected to milling edge operation by a milling machine, and the process frame is removed according to the designed dimensional requirements, and divided into finished printed circuit boards meeting the design requirements.

[0079] Cleaning: It is to use a soft brush to brush and ultrasonic cleaning to remove the contamination and dust on the surface of the printed circuit board, and then perform drying.

[0080] Electrical testing: It is to perform open - short circuit testing and insulation testing on the circuit pattern of the printed circuit board, and perform resistance value testing on the resistance wires.

[0081] Final inspection: It is to check the integrity of the board surface pattern of the printed circuit board, the compliance of the structural dimensions with the design documents, etc.

[0082] Packaging and processing: It is to package the qualified finished products according to the customer's requirements and send them to the customer for use.

[0083] Example 3:

[0084] Embodiment 3 provides a printed circuit board which is fabricated by using the fabrication method of the printed circuit board described in Embodiment 2 above.

[0085] Note: The suffixes "A", "B", etc. of the component names in this specification (such as the intermediate board A, the intermediate board B, etc.) are only for the convenience of clear description, rather than for limiting the scope of implementation of this invention patent.

[0086] In summary, the fabrication method of the long resistance wire according to the present invention is simple, reasonable, and easy to operate and implement. Moreover, the obtained long resistance wire not only well meets the requirement of a specific resistance value, but also has a very high resistance value accuracy, thus well meeting the processing requirements of the printed circuit board.

[0087] In the above description, many specific details are set forth in order to provide a thorough understanding of the present invention. However, the above description is only a preferred embodiment of the present invention, and the present invention can be implemented in many other ways different from those described herein. Therefore, the present invention is not limited by the specific embodiments disclosed above. At the same time, any person skilled in the art can make many possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above, or modify it into an equivalent embodiment with equivalent changes. All modifications, equivalent changes, and decorations made to the above embodiments based on the technical essence of the present invention without departing from the technical solution of the present invention still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for making a long resistance wire, characterized in that: include: Providing a processing board (1), wherein two outermost layers of the processing board (1) facing each other are both copper foil layers (10); Processing a tool hole at a preset position of the processing plate (1), wherein the tool hole comprises a plurality of wire holes (12) penetrating the two copper foil layers (10); The processing board (1) is subjected to circuit fabrication, so that conductive connecting pieces (20) are respectively fabricated in the plurality of wire holes (12), and circuit patterns are respectively fabricated on the two copper foil layers (10); the circuit patterns on each of the copper foil layers (10) include a plurality of short resistance line segments (21), and the plurality of short resistance line segments (21) on the two copper foil layers (10) are further connected in series through the plurality of conductive connecting pieces (20) to form a long resistance line; in addition, the cross-sectional area of ​​the conductive connecting piece (20) is greater than twice the cross-sectional area of ​​the short resistance line segment (21); The circuit pattern is inspected and corrected by AOI.

2. The method for making a long resistance wire according to claim 1, characterized in that: The processing board (1) is sequentially subjected to chemical copper deposition, full-board electroplated copper layer, lamination pretreatment, anti-plating photosensitive film coating, exposure, development, pattern electroplated copper layer, electroplated tin layer, film stripping, alkaline copper etching, and removal of tin plating layer processing to produce the conductive connector (20) and the circuit pattern.

3. The method for making a long resistance wire according to claim 2, characterized in that: The wire-passing hole (12) is a cylindrical hole, and the conductive connector (20) is a cylindrical ring-shaped copper layer formed on the inner circumference of the wire-passing hole (12); accordingly, the cross-sectional area of ​​the conductive connector (20) satisfies the following formula: S1=π×D×h1; wherein D is the diameter of the wire-passing hole (12), and h1 is the copper thickness of the conductive connector (20); The cross-sectional area of ​​the short resistance line segment (21) satisfies the following formula: S2=W×h2; wherein W is the line width of the short resistance line segment (21), and h2 is the copper thickness of the short resistance line segment (21).

4. The method for making a long resistance wire according to claim 3, characterized in that: The diameter of the wire hole (12) is 0.4-0.6 mm; the copper thickness of the conductive connector (20) is 0.02-0.03 mm; The short resistance line segment (21) has a line width of 0.3-0.5 mm and a copper thickness of 0.04-0.06 mm.

5. The method for manufacturing a long resistance wire according to claim 4, characterized in that: The length of the short resistance line segment (21) is 90 to 120 mm, and the total number of the short resistance line segments (21) located on the two copper foil layers (10) is 30 to 40.

6. The method for manufacturing a long resistance wire according to claim 2, characterized in that: The processing parameters of the above-mentioned full-board electroplated copper layer are: the temperature of the copper plating solution is 20-35°C, the concentration of copper sulfate in the copper plating solution is 50-100g / L, the concentration of sulfuric acid is 150-225g / L, the chloride ion content is 30-80PPM, and the concentration of brightener is 4-10mL / L; the current density is 1.2-1.8A / dm 2 , the electroplating time is 18 to 25 minutes.

7. The method for manufacturing a long resistance wire according to claim 2, characterized in that: The processing parameters of the above-mentioned pattern electroplated copper layer are: the temperature of the copper plating solution is 20-30°C, the concentration of copper sulfate in the copper plating solution is 60-90g / L, the concentration of sulfuric acid is 150-225g / L, the content of chloride ions is 30-80PPM, and the concentration of brightener is 6-10mL / L; the current density is 1.5-2.2A / dm 2 , the electroplating time is 50 to 65 minutes.

8. The method for making a long resistance wire according to claim 2, characterized in that: When performing the above-mentioned film stripping, alkaline copper etching and tin plating removal processes, the pH value of the liquid used is 8.4-8.8, the temperature is 45-55°C, and the injection pressure is 0.8-3kg / cm 2 , and the board conveying speed is 3 to 5 m / min, and the etching factor is not less than 2.

6.

9. A method for manufacturing a printed circuit board, characterized in that: include: Providing an intermediate plate, the intermediate plate being provided with a long resistance wire made by the method for making a long resistance wire according to any one of claims 1 to 8; The middle plate is processed in sequence with conventional resin plugging, solder masking, character printing, hot air leveling, molding, cleaning and electrical testing to obtain a printed circuit board.

10. A printed circuit board, characterized in that: The printed circuit board is manufactured by the method for manufacturing the printed circuit board as claimed in claim 9.

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