Production process of a double-sided PCB board

Abstract

The present invention relates to the field of PCB board production and manufacturing, and specifically relates to a production process of a double-sided PCB board. The laminated structure of the double-sided PCB board is successively a top solder mask, a top copper foil, a top soft glue, a bare board, a bottom soft glue, a bottom copper foil, and a bottom solder mask. A die cutting machine is also included in the production of the double-sided PCB board, and the die cutting machine includes male die cutting and female die cutting. The present invention simplifies the production process, reduces the etching process at the same time, greatly reduces the generation of various pollutants and the waste of energy, realizes the conservation and reuse of water resources, solves the problems of excessive etching or incomplete etching in the existing circuit board production, reduces the scrap rate, solves the burrs and notches on the circuit in the existing circuit board etching production, avoids the quality problems caused by tip discharge during the power-on use process, and solves the problem of a large amount of waste of various inks and screen printing materials in the existing circuit board production process.

Description

Technical Field

[0001] The present invention belongs to the field of production and manufacturing of PCB boards, and particularly relates to a production process of double-sided PCB boards. Background Art

[0002] With the development of electronic information and the progress of technology, the production of circuit boards, which are indispensable in the production of electronic products, has seen a substantial and rapid development. At the same time, it is developing in the direction of high density and high precision. Circuit boards with various requirements are everywhere in all aspects of the electronics industry. However, the production of circuit boards mainly involves removing excess copper on the copper clad laminate and forming circuits. Since circuit boards are becoming increasingly fine and tiny, the processing accuracy is increasing day by day, making the production of printed circuit boards more and more complex. Its production process has dozens of processes, and chemical substances enter the water in each process.

[0003] The pollutants in the wastewater from the design and production of printed circuit boards are as follows:

[0004] I. Copper. Since the excess copper is removed from the copper clad laminate to leave the circuit, copper is the main pollutant in the wastewater from the design of printed circuit boards, and copper foil is the main source. In addition, since the circuits of each layer of double-sided boards and multi-layer boards need to be conducted, holes are drilled in the substrate and copper is plated to conduct the circuits of each layer. There is also electroless copper plating on the first layer of the substrate (usually resin) and in the intermediate process. Electroless copper plating uses complex copper to control a stable copper deposition rate and copper deposition thickness. Generally, EDTA-Cu (sodium copper ethylenediaminetetraacetate) is used, and there are also unknown components. The cleaning water of the printed circuit board after electroless copper plating also contains complex copper. In addition, there is nickel plating, gold plating, and tin-lead plating in the production of printed circuit boards, so these heavy metals are also contained.

[0005] II. Organics. In processes such as making circuit patterns, copper foil etching, and circuit soldering, ink is used to cover the copper foil parts that need to be protected, and then it is removed after completion. These processes generate high-concentration organics, and some of them have a COD as high as 10 - 20 g / L. These high-concentration wastewaters account for about 5% of the total water volume and are also the main source of COD in the wastewater from the production of printed circuit boards.

[0006] III. Ammonia nitrogen. Depending on the production process, in some processes, the etching solution contains ammonia water, ammonium chloride, etc., which are the main sources of ammonia nitrogen.

[0007] IV. Other pollutants. In addition to the above main pollutants, there are also acids, alkalis, nickel, lead, tin, manganese, cyanide ions, and fluorine. In the production process of printed circuit boards, sulfuric acid, hydrochloric acid, nitric acid, sodium hydroxide are used, and there are dozens of various commercial liquid medicines such as etching solutions, electroless plating solutions, electroplating solutions, activation solutions, and pre-impregnation solutions. The components are complex. Except for most of the components being known, there are also a small number of unknown components, which makes the wastewater treatment more complex and difficult.

[0008] Therefore, PCB enterprises should attach great importance to environmental protection and cleaner production. To solve the above problems, it is necessary to further improve the production of the PCB industry and reduce the generation of pollutants. Summary of the Invention

[0009] In view of the deficiencies of the prior art, the present invention provides a production process for double-sided PCBs. This operation reduces the etching process, avoids the generation of etching wastewater, and at the same time reduces multiple cleaning processes. Since a large amount of etching solution and electroplating solution are not required, the generation of organic matter, ammonia nitrogen, and other pollutants is also significantly reduced.

[0010] To solve the above technical problems, the present invention provides the following technical solutions:

[0011] A production process for a double-sided PCB board, the double-sided PCB board includes a bare board, a top layer soft glue, a bottom layer soft glue, a top layer copper foil, a bottom layer copper foil, a top layer solder mask, and a bottom layer solder mask. The laminated structure of the double-board PCB board is successively the top layer solder mask, the top layer copper foil, the top layer soft glue, the bare board, the bottom layer soft glue, the bottom layer copper foil, and the bottom layer solder mask. The production of the double-sided PCB board also includes a die-cutting machine, and the die-cutting machine includes male die cutting and female die cutting; the production process of the double-sided PCB board includes the following steps:

[0012] S1: Blanking, and the blanking is for the bare board blanking;

[0013] S2: Die-cutting machine cutting and cold pressing;

[0014] S3: Laminating;

[0015] S4: Drilling;

[0016] S5: Electroless copper plating:

[0017] S6: Die-cutting and laminating and curing;

[0018] S7: Shaping;

[0019] S8: Inspection.

[0020] According to the design concept of the present invention, before the blanking of the present invention, there is also layout, and the layout is the large board PNL layout of the double-sided PCB board.

[0021] According to the design concept of the present invention, the blanking size of the present invention is at least 1 mm larger than the layout size.

[0022] According to the design concept of the present invention, the die-cutting and cold pressing of the die-cutting machine of the present invention includes the cutting of copper foil, and the copper wire on the copper foil is cold-pressed and bonded together with the top soft glue or the bottom soft glue. The copper wire on the top copper foil and the top soft glue are combined into the top circuit layer, and the copper wire on the bottom copper foil and the bottom soft glue are combined into the bottom circuit layer.

[0023] According to the design concept of the present invention, the top circuit layer, the bare board, and the bottom circuit layer of the present invention are laminated and aligned and pressed in sequence to form a core board with circuit layers on both sides.

[0024] According to the design concept of the present invention, the electroless copper plating of the present invention is the copper plating on the hole wall of the metallized hole, and the thickness of the copper plating on the hole wall meets the production requirements and acceptance standards.

[0025] According to the design concept of the present invention, the die-cutting machine presses and cures to cut out the opening positions of the top solder mask and the bottom solder mask by the die-cutting machine. The top solder mask and the bottom solder mask are respectively aligned and pressed with the top circuit and the bottom circuit. In order to avoid poor pressing, the pressing structure is further cured by a curing method.

[0026] According to the design concept of the present invention, characters are printed on the top solder mask and the bottom solder mask, and the positions and structures of the characters are the same as those of the silk screen fonts on the double-sided PCB board.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The production process is simplified, and at the same time, the etching process is reduced, greatly reducing the generation of various pollutants and the waste of energy. At the same time, the conservation and reuse of water resources are realized.

[0029] (2) The problems of excessive etching or incomplete etching in the production of existing circuit boards are solved, the rejection rate is reduced, and the quality of the circuit boards is improved.

[0030] (3) The burrs and notches on the circuit in the etching production of existing circuit boards are solved, and the quality problems caused by tip discharge during the power-on use process are avoided.

[0031] (4) The problems of a large amount of waste of various inks and silk screen materials in the production process of existing circuit boards are solved, and at the same time, the waste of materials such as multiple exposures and film stripping in production is avoided, and the production cost is reduced. Specific embodiments

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0033] First of all, it should be noted that for the production process of the double-sided PCB board of the present invention, the double-sided PCB board includes a bare board, a top layer soft glue, a bottom layer soft glue, a top layer copper foil, a bottom layer copper foil, a top layer solder mask, and a bottom layer solder mask. The laminated structure of the double-sided PCB board is, in sequence, the top layer solder mask, the top layer copper foil, the top layer soft glue, the bare board, the bottom layer soft glue, the bottom layer copper foil, and the bottom layer solder mask. The production of the double-sided PCB board also includes a die-cutting machine, and the die-cutting machine includes male die cutting and female die cutting. The production process of the double-sided PCB board includes the following steps:

[0034] S1: Blanking, and the blanking is the blanking of the bare board. Before the blanking of the present invention, there is also layout, and the layout is the large board PNL layout of the double-sided PCB board. The PNL layout is the effective area of the double-sided PCB layout, that is, the area within the outermost closed area formed by all the outline lines after the double-sided PCB board is arranged. The blanking size of the present invention is greater than the minimum single side of the PNL layout size by 1 mm, which is much smaller than the conventional blanking size that is greater than the PNL layout size by 4 - 10 mm. For the convenience of operation and to enhance the maneuverability of the operation, it is preferably that on the basis that the three sides of the blanking size are greater than the PNL layout size by 1 mm, the fourth side blanking size is greater than the PNL layout size by 2 - 4 mm.

[0035] S2: Die-cutting machine cutting and cold pressing; the die-cutting machine cutting and cold pressing includes the cutting of the copper foil. The cutting of the copper foil is to cut out the corresponding copper wires or isolated copper PADs. The cutting of the copper wires and the isolated copper PADs respectively use male die cutting and / or female die cutting. The copper wires and the isolated copper PADs on the copper foil are cold-pressed together with the top layer soft glue or the bottom layer soft glue. The copper wires on the top layer copper foil and the top layer soft glue form the top layer circuit layer, and the copper wires on the bottom layer copper foil and the bottom layer soft glue form the bottom layer circuit layer.

[0036] In the cutting of the copper foil, it is divided into the cutting of the copper wires and the cutting of the isolated copper PADs. The isolated copper PAD is an isolated point with the longest dimension of the copper point less than 3 mm. Under the action of the driving roller, the top layer soft glue or the bottom layer soft glue is closely combined with the male die cutting and / or female die cutting. The cut copper wires or isolated copper PADs are cold-pressed together through the driving of the driving roller by the pressure roller.

[0037] The copper foil, the top layer soft glue, and the bottom layer soft glue are all installed on the die-cutting machine in a rolled and rolling manner.

[0038] S3: Laminating; the top layer circuit layer, the bare board, and the bottom layer circuit layer are laminated in sequence and aligned for lamination to form a core board with circuit layers on both sides. Alignment PADs and positioning holes are provided on both the top layer circuit and the bottom layer circuit.

[0039] S4: Drilling; since the core board after lamination is a core board with finished circuits, isolated copper PADs are likely to fall off during drilling. For isolated copper PADs corresponding to the drilled holes, they are preferably enlarged by 2 - 6 mm.

[0040] S5: Electroless copper plating: For the electroless copper plating, the outer circuit is covered with a protective film by means of a hole - blocking film, and copper is deposited inside the metallized holes. The thickness of the copper deposited on the hole wall is greater than 18 um.

[0041] S6: Die - cutting, laminating and curing. The die - cutting machine laminates and cures to cut out the openings of the top layer solder mask and the bottom layer solder mask. The top layer solder mask and the bottom layer solder mask are single - sided colloid structures. After cutting, the colloid in the openings is discarded. The top layer solder mask and the bottom layer solder mask are separated by the die - cutting machine respectively. The colloid part is combined with the top layer circuit or the bottom layer circuit, and the protective film of the colloid is peeled off. To avoid poor lamination, the lamination structure is further cured by a curing method.

[0042] According to the design concept of the present invention, characters are printed on the top layer solder mask and the bottom layer solder mask of the present invention, and the positions and structures of the characters are the same as those of the silk - screen fonts on the double - sided PCB board.

[0043] S7: Shaping.

[0044] S8: Inspection.

[0045] Through the cutting of the die - cutting machine in the present invention, copper foils are cut into copper wires or isolated copper PADs at corresponding positions, so that the copper foils form circuit patterns, reducing the etching process in the production of circuit boards, thus simplifying the production process of circuit boards and improving production efficiency; since the etching process is reduced, the use of etching solution is reduced, not only reducing production costs, but also effectively avoiding the generation of pollutants during the etching process, being more energy - saving and environmentally friendly; since the etching process is reduced, over - etching and incomplete etching during the etching process are avoided, and at the same time, burrs and notches in the etching production of circuit boards are avoided, reducing the appearance of defective products and improving the quality of circuit boards; since the etching process is reduced, the corresponding pre - processes are reduced, not only shortening the production period and improving production efficiency, but also reducing the use of raw materials for pre - processes and lowering production costs.

[0046] It should be noted that the term "comprising", "including" or any other variation thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device.

[0047] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. Production process of a double-sided PCB board, characterized in that, the double-sided PCB board includes a bare board, a top soft glue, a bottom soft glue, a top layer circuit, a bottom layer circuit, a top layer solder mask, and a bottom layer solder mask. The lamination structure of the double-sided PCB board is, in sequence, the top layer solder mask, the top layer circuit, the top soft glue, the bare board, the bottom soft glue, the bottom layer circuit, and the bottom layer solder mask. The production process of the double-sided PCB board further includes a die-cutting machine, and the die-cutting machine includes male die cutting and female die cutting; The production process of the double-sided PCB board includes the following steps: S1: Blanking, and the blanking is for the bare board blanking; S2: Die-cutting and cold pressing by the die-cutting machine, including cutting of the top layer copper foil and cutting of the bottom layer copper foil. The copper wire after cutting the top layer copper foil is cold-pressed and bonded with the top soft glue to form the top layer circuit layer, and the copper wire after cutting the bottom layer copper foil is cold-pressed and bonded with the bottom soft glue to form the bottom layer circuit layer; S3: Laminating, the top layer circuit layer, the bare board, and the bottom layer circuit layer are laminated in sequence and aligned and laminated to form a core board with circuit layers on both sides; S4: Drilling; S5: Chemical copper plating; S6: Die-cutting and laminating and curing, including the die-cutting machine respectively cutting out the opening positions of the top layer solder mask and the bottom layer solder mask. The cut top layer solder mask and bottom layer solder mask are respectively aligned and laminated with the top layer circuit and the bottom layer circuit. In order to avoid insecure lamination, the laminated structure is further cured by a curing method; S7: Shaping; S8: Inspection.

2. The production process of the double-sided PCB board according to claim 1, characterized in that, before the blanking, there is also layout, and the layout is the large board PNL layout of the double-sided PCB board.

3. The production process of the double-sided PCB board according to claim 2, characterized in that, the blanking size is 1 mm larger than the minimum single side of the PNL layout size.

4. The production process of the double-sided PCB board according to claim 1, characterized in that, the chemical copper plating is copper plating on the hole wall of the metallized hole, and the thickness of the copper plating on the hole wall meets the production requirements and acceptance standards.

5. The production process of the double-sided PCB board according to claim 1, characterized in that, characters are printed on the top layer solder mask and the bottom layer solder mask, and the positions and structures of the characters are the same as those of the silk screen fonts on the double-sided PCB board.