WO2024087916A1

WO2024087916A1 - Manufacturing method for metallic aluminum circuit board, and metallic aluminum circuit board and circuit board module

Info

Publication number: WO2024087916A1
Application number: PCT/CN2023/118177
Authority: WO
Inventors: 王定锋; 代宏信; 徐磊; 王晟齐; 徐文红
Original assignee: 王定锋
Priority date: 2022-10-29
Filing date: 2023-09-12
Publication date: 2024-05-02

Abstract

Disclosed in the present invention are a manufacturing method for a metallic aluminum circuit board, and a metallic aluminum circuit board and a circuit board module. The manufacturing method comprises: preparing an aluminum-coated substrate, wherein the aluminum-coated substrate comprises an insulating substrate layer and a front-face aluminum layer located on one face of the insulating substrate layer; manufacturing anti-etching ink on the front-face aluminum layer, and covering the aluminum layer where a circuit and a conductive wire need to be formed; etching the aluminum-coated substrate using an etching method, and etching the front-face aluminum layer to form a front-face aluminum circuit layer and an aluminum conductive wire, wherein all the circuits of the front-face aluminum circuit layer are interconnected and conducting by means of the aluminum conductive wire; removing the anti-etching ink; manufacturing a front-face solder mask on the front-face aluminum circuit layer, wherein the front-face solder mask partially covers the front-face aluminum circuit layer, so as to expose an aluminum pad; electroplating the aluminum pad with a tinphilic metal using an electroplating method; and disconnecting the aluminum conductive wire. Therefore, it is ensured that a pad has good solderability, and the manufacturing cost of a circuit board is also greatly reduced.

Description

A method for manufacturing a metal aluminum circuit board, a metal aluminum circuit board and a circuit board module

Technical Field

The present invention relates to the field of circuit boards, and in particular to a method for manufacturing a metal aluminum circuit board, a metal aluminum circuit board and a circuit board module.

Background technique

Since copper has good solderability and conductivity, when soldering electronic components, the copper pad can combine well with tin to firmly and reliably solder and fix the electronic components. Therefore, copper is generally used as the circuit layer in existing circuit boards. However, with the development of the industry over the years, circuit boards have become quite mature, with serious product homogeneity. Consumers are highly sensitive to the price of electronic products. In order to gain a competitive advantage in the fierce market competition, how to reduce the production cost of circuit boards has become one of the development directions of the circuit board industry.

In order to significantly reduce the cost of circuit boards, there is a trend of using aluminum foil instead of copper foil to make circuit boards. There are two processes for making circuit boards with aluminum foil in the prior art: ① One is to make aluminum foil and insulating film into an aluminum-coated plate with adhesive, then etch out aluminum circuits, and then make a solder mask to form an aluminum pad, and then chemically plate a metal with good solderability at the pad position. The surface is now chemically plated with silver, tin or nickel. When chemically plating these metals, impurities produced by side reactions in the chemical reaction process will be sandwiched in the chemical plating layer, which seriously affects the solderability of the plating layer. In addition, the concentration of the reactants in chemical plating changes rapidly, making the chemical reaction rate unstable; ② Another method is to use copper-aluminum composite foil to make circuit boards. The copper-aluminum composite foil is made into a copper-aluminum laminated substrate with the copper layer exposed, and then etched into circuits. Since etching removes both copper and aluminum, the etching reaction liquid contains both copper ions and aluminum ions. The etching liquid is difficult to control and has poor stability. In addition, the waste etching liquid recovery and treatment process is complicated. There is a layer of copper on the entire circuit surface, and the cost is higher than making copper, nickel, silver, and tin with good solderability only on the pad. Therefore, the overall cost of this method is still very high.

Therefore, how to significantly reduce the production cost of circuit boards while ensuring that the pads have good solderability has become an urgent problem to be solved in the circuit board industry.

Summary of the invention

In order to solve at least one of the above-mentioned prior art problems, the present invention provides a method for manufacturing a metal aluminum circuit board, a metal aluminum circuit board and a circuit board module, which can ensure that the solder pad has good solderability while greatly Greatly reduces the production cost of circuit boards.

In a first aspect, an embodiment of the present invention provides a method for manufacturing a metal aluminum circuit board, comprising:

Preparing an aluminum-clad substrate, wherein the aluminum-clad substrate comprises an insulating substrate layer and a front aluminum layer located on one side of the insulating substrate layer;

Prepare an anti-etching ink on the front aluminum layer to cover the aluminum layer where circuits and conductive lines need to be formed;

Etching the aluminum-clad substrate by an etching method to form a front aluminum circuit layer and aluminum conductive wires by etching the front aluminum layer, wherein the aluminum conductive wires interconnect all the circuits of the front aluminum circuit layer;

Removal of etch-resistant ink;

A front solder resist layer is formed on the front aluminum circuit layer, and the front solder resist layer partially covers the front aluminum circuit layer to expose the aluminum pad;

Electroplating a tin-philic metal onto the aluminum pad using an electroplating method;

Disconnect the aluminum conductive wire.

Optionally, the aluminum-clad substrate is a single-sided aluminum-clad substrate, a front aluminum layer is provided on one side of the insulating substrate layer, and there is no aluminum layer on the other side, and the circuit board is a single-sided circuit board; or, the aluminum-clad substrate is a double-sided aluminum-clad substrate, and also includes a back aluminum layer provided on the other side of the insulating substrate layer, and the circuit board is a double-sided circuit board.

Optionally, the back aluminum layer is a back aluminum circuit layer, and the aluminum-clad substrate also includes a back solder resist layer arranged on the back aluminum circuit layer; or the back aluminum layer is aluminum foil, and in the etching process, the back aluminum foil is simultaneously etched to form the back aluminum circuit layer, and in the solder resist layer manufacturing process, the back solder resist layer is simultaneously manufactured on the back aluminum circuit layer.

Optionally, the aluminum-clad substrate is a single-sided aluminum-clad substrate, with a front aluminum layer on one side of the insulating substrate layer and no aluminum layer on the other side. After the front aluminum layer is etched and before the electroplating process, the back aluminum circuit layer is fixed to the insulating substrate layer of the aluminum-clad substrate by adhesive to form a double-sided circuit board.

Optionally, it also includes a pad hole, which passes through the front solder mask layer, the front aluminum circuit layer and the insulating substrate layer, and the back aluminum circuit layer is exposed in the pad hole. Before electroplating, an extrusion die is used to extrude the front aluminum circuit layer and the back aluminum circuit layer to form contact and conduction. During electroplating, the surface of the back aluminum circuit layer in the pad hole is plated with a tin-philic metal.

Optionally, after the electroplating process is completed, the electroplated circuit board is punched using a mold on a roll-to-roll punching machine. The aluminum conductive wire is punched out to disconnect the aluminum conductive wire, wherein a punch hole is formed at the punched out portion of the aluminum conductive wire, and the punch hole runs through the entire circuit board.

Optionally, when making the solder mask layer, the aluminum conductive wire is exposed and anti-plating ink is printed. After the electroplating process is completed, the anti-plating ink is removed using an alkaline solution, and the alkaline solution simultaneously corrodes and disconnects the aluminum conductive wire.

Optionally, after the aluminum conductive wire is disconnected, shielding ink is made at the disconnection position of the aluminum conductive wire to shield the fracture of the aluminum conductive wire, and a part of the shielding ink is stacked on the front solder resist layer.

Optionally, the tin-philic metal is copper, tin, silver or nickel.

Optionally, the front solder resist layer is solder resist ink or solder resist covering film.

The first aspect of the present invention has at least one of the following beneficial effects: by adding aluminum conductive wires during circuit design, all circuits of the front aluminum circuit layer are interconnected and connected by using the aluminum conductive wires, and when making the front solder mask layer, the front solder mask layer exposes the aluminum pad, and then uses the electroplating process to electroplate the tin-philic metal, so that only a layer of tin-philic metal is electroplated on the surface of the aluminum pad. Compared with the chemical plating in the prior art, the anode metal loses electrons to form metal ions during electroplating, and then obtains electrons on the surface of the cathode aluminum pad to form metal atoms deposited on the pad surface. The metal ion concentration in the solution is stable and consistent, the thickness of the electroplated layer is stable, and there is no external reducing agent like chemical plating. The plating impurities brought by the electroplating are eliminated, and no impurities of the side reaction products are deposited in the plating, which ensures the good solderability of the metal pad after electroplating. Since there are no side reaction impurities in the waste etching liquid, the recovery process is relatively simple and low in cost. Compared with the copper-aluminum composite foil in the prior art, the present invention only has tin-philic metals such as copper or silver at the pad position, which is obviously lower in cost than the solution with a layer of copper on the entire circuit surface, and also solves the difficulty of etching two metals. The recovery and treatment of the waste electroplating liquid also becomes easier and lower in cost. While meeting the good solderability of the pad, the present invention greatly reduces the production cost of the circuit board, which is conducive to the circuit board and related products to obtain good market competitiveness.

In the second aspect, an embodiment of the present invention provides a metal aluminum circuit board, comprising an insulating substrate layer, a front aluminum circuit layer bonded to the insulating substrate layer, and a front solder resist layer bonded to the front aluminum circuit layer, wherein a pad window is provided on the front solder resist layer, and the front aluminum circuit layer forms an aluminum pad at the pad window, and a tin-philic metal layer is bonded to the surface of the aluminum pad, and the tin-philic metal layer has a thickness of 1 micron-20 microns, and the front aluminum circuit layer comprises a plurality of circuits, and at least some of the circuits have fractures, and the fractures penetrate the front solder resist layer and the front aluminum circuit layer.

Optionally, the fracture penetrates the insulating substrate layer, the aluminum section at the fracture and the section of the insulating substrate layer are located on the same knife-cut surface, and the side surface of the front aluminum circuit layer at the fracture is not blocked by the front solder resist layer; Alternatively, the fracture does not penetrate the insulating substrate layer, and the side surface of the front aluminum circuit layer at the fracture is not blocked by the front solder resist layer.

Optionally, shielding ink is provided at the fracture, and the shielding ink shields the aluminum side surface at the fracture, and a part of the shielding ink is stacked on the front solder resist layer.

Optionally, the circuit board is a single-sided circuit board, and the insulating substrate layer forms a back solder resist layer; or the circuit board is a double-sided circuit board, including a back aluminum circuit layer bonded to the insulating substrate layer, the back aluminum circuit layer is bonded to a back solder resist layer, and the front aluminum circuit layer and the back aluminum circuit layer are in contact and conductive.

Optionally, it also includes a pad hole, which penetrates the front solder mask layer, the front aluminum circuit layer and the insulating substrate layer, and the back aluminum circuit layer is exposed in the pad hole to form a back aluminum pad, and the surface of the back aluminum pad is combined with a tin-philic metal layer.

Optionally, the tin-philic metal is copper, tin, silver or nickel.

The second aspect of the present invention has at least one of the following beneficial effects: a tin-philic metal layer is combined with the surface of the aluminum pad, the thickness of the tin-philic metal layer is 1 micron-20 microns, the front aluminum circuit layer includes multiple circuits, at least some of the circuits have fractures, and the fractures penetrate the front solder mask layer and the front aluminum circuit layer. The circuit board can use an electroplating process to electroplate the tin-philic metal, so that only a layer of tin-philic metal is electroplated on the surface of the aluminum pad. Compared with the chemical plating in the prior art, the anode metal loses electrons to form metal ions during electroplating, and then obtains electrons on the cathode aluminum pad surface to form metal atoms deposited on the pad surface. The metal ion concentration in the solution is stable and consistent, the thickness of the electroplated layer is stable, and there is no chemical plating. The plating impurities brought by the external reducing agent in electroplating, and no impurities of side reaction products are deposited in the plating layer, which ensures the good solderability of the metal pad after electroplating. Since there are no side reaction impurities in the waste etching liquid, the recovery process is relatively simple and low in cost. Compared with the copper-aluminum composite foil in the prior art, the present invention only has tin-philic metals such as copper or silver at the pad position, which is obviously lower in cost than the solution with a layer of copper on the entire circuit surface, and also solves the difficulty of etching two metals. The recovery and treatment of the waste electroplating solution also becomes easier and lower in cost. While meeting the good solderability of the pad, the present invention greatly reduces the production cost of the circuit board, which is conducive to the circuit board and related products to obtain good market competitiveness.

In a third aspect, an embodiment of the present invention provides a circuit board module, comprising the metal aluminum circuit board described in any one of the embodiments of the second aspect, wherein electronic components are welded on the tin-philic metal layer.

Optionally, the circuit board module is a lamp, a printer, a computer or a car.

Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the methods and structures particularly pointed out in the description and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are used to provide a further understanding of the technical solution of the present invention and constitute a part of the specification. Together with the embodiments, they are used to explain the technical solution of the present invention and do not constitute a limitation on the technical solution of the present invention.

FIG1 is a schematic diagram of the planar structure of a front aluminum circuit layer obtained after etching the front aluminum layer in an embodiment of the present invention;

Figure 1-1 is a partial enlarged view of A in Figure 1;

Figure 1-1-1 is a partial enlarged view of B in Figure 1-1;

FIG1-2 is a cross-sectional view along the A'-A' direction in FIG1-1-1 (single-sided circuit board);

Figure 1-3 is a cross-sectional view in the B'-B' direction in Figure 1-1-1 (for single-sided circuit board, in order to facilitate the placement of drawings and reading, the cross-sectional view is rotated 90° in the opposite direction to be placed horizontally, the same below);

FIG1-4 is a cross-sectional view along the A'-A' direction in FIG1-1-1 (double-sided circuit board);

Figure 1-5 is a cross-sectional view of the B'-B' direction in Figure 1-1-1 (double-sided circuit board). For single-sided circuit board, in order to facilitate the placement of drawings and reading, the cross-sectional view is rotated 90° in the opposite direction to be placed horizontally, the same below);

FIG2 is a schematic diagram of the planar structure of FIG1 after a front solder resist layer is produced;

Figure 2-1 is a partial enlarged view of C in Figure 2;

FIG2-2 is a cross-sectional view of FIG1-2 after a front solder mask layer is made;

FIG2-3 is a cross-sectional view of FIG1-3 after a front solder mask layer is made;

FIG2-4 is a cross-sectional view of FIG1-4 after a front solder mask layer is made;

FIG2-5 is a cross-sectional view of FIG1-5 after a front solder mask layer is made;

FIG3 is a schematic diagram of a planar structure of FIG2 after anti-plating ink is produced at the position of the aluminum conductive line;

FIG3-1 is a partial enlarged view of D in FIG3;

FIG3-2 is a cross-sectional view of FIG2-2 after anti-plating ink is produced;

FIG3-3 is a cross-sectional view of FIG2-3 after anti-plating ink is produced;

FIG3-4 is a cross-sectional view of FIG2-4 after anti-plating ink is produced;

FIG3-5 is a cross-sectional view of FIG2-5 after anti-plating ink is produced;

Figure 4-1 is a cross-sectional view of Figure 3 at the pad position (single-sided circuit board, direction is B'-B' direction, the interception position is at the pad, in order to facilitate the placement of drawings and reading, the cross-sectional view is rotated 90° in the opposite direction to be placed horizontally, the same below);

FIG4-2 is a cross-sectional view of FIG4-1 after electroplating with a tin-philic metal;

FIG4-3 is a cross-sectional view of FIG3 at the pad position (double-sided circuit board, direction is B'-B' direction, the interception position is at the pad, for the convenience of placing drawings and reading, the cross-sectional view is rotated 90° in the opposite direction to be placed horizontally, the same below);

FIG4-4 is a cross-sectional view of FIG4-3 after electroplating with a tin-philic metal;

FIG5 is a schematic diagram of the planar structure of FIG3 after the aluminum conductive wire is disconnected;

Figure 5-1 is a partial enlarged view of E in Figure 5;

Figure 5-2 is a partial enlarged view of F in Figure 2;

FIG5-3 is a schematic diagram of the structure of FIG5-2 after the aluminum conductive wire is disconnected;

Figure 5-4 is a schematic diagram of the structure of Figure 5-2 after the front solder mask layer is hidden (in order to clearly express the structure, the scale of the figure is reduced relative to Figure 5-2);

Figure 5-5 is a schematic diagram of the structure of Figure 5-3 after the solder mask layer is hidden (in order to clearly express the structure, the scale of the figure is reduced relative to Figure 5-2);

FIG5-6 is a cross-sectional view of FIG3-2 after being treated with an alkaline solution (the aluminum conductive wire and the anti-plating ink are corroded);

FIG5-7 is a cross-sectional view of FIG3-3 after being treated with an alkaline solution (the aluminum conductive wire and the anti-plating ink are corroded);

FIG5-8 is a cross-sectional view of FIG3-4 after being treated with an alkaline solution (the aluminum conductive wire and the anti-plating ink are corroded);

FIG5-9 is a cross-sectional view of FIG3-5 after being treated with an alkaline solution (the aluminum conductive wire and the anti-plating ink are corroded);

FIG5-10 is a cross-sectional view of the aluminum conductive wire and the insulating substrate layer in FIG2-2 after being cut;

FIG5-11 is a cross-sectional view of the aluminum conductive wire and the insulating substrate layer in FIG2-3 after being cut;

FIG5-12 is a cross-sectional view of the aluminum conductive wire, the insulating substrate layer, the back aluminum circuit layer and the back solder resist layer in FIG2-4 after being cut;

FIG5-13 is a cross-sectional view of the aluminum conductive wire, the insulating substrate layer, the back aluminum circuit layer and the back solder resist layer in FIG2-5 after being cut;

6 is a schematic diagram of a punching die for punching aluminum conductive wires in an embodiment of the present invention;

FIG7 is a schematic diagram of the planar structure of FIG5 after the shielding ink is produced;

FIG7-1 is a partial enlarged view of G in FIG7;

FIG7-2 is a cross-sectional view of FIG5-6 after masking ink is produced;

FIG7-3 is a cross-sectional view of FIG5-7 after masking ink is produced;

FIG7-4 is a cross-sectional view of FIG5-8 after masking ink is produced;

FIG7-5 is a cross-sectional view of FIG5-9 after masking ink is produced;

8 is a cross-sectional view of a double-sided circuit board with pad holes in an embodiment of the present invention;

Explanation of the accompanying drawings: 1-front aluminum circuit layer, 11-circuit, 12-aluminum pad, 13-shielding ink, 14-fracture, 2-aluminum conductive wire, 3-back solder mask, 4-front solder mask, 41-conductive wire window, 5-anti-plating ink, 6-tin-philic metal layer, 7-punching mold, 71-upper mold, 72-lower mold, 73-thrust pin, 8-punching, 9-back aluminum circuit layer, 10-middle insulating layer, 15-pad hole.

Detailed ways

To make the purpose, technical solution and advantages of the present invention more clear, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the embodiments and features in the embodiments described below can be combined with each other arbitrarily without conflict.

Many different implementations or examples are provided below for realizing the method and structure of the present invention. The front side refers to the upper surface shown in the figure, and the back side corresponds to the lower surface shown in the figure.

An embodiment of a first aspect of the present invention provides a method for manufacturing a metal aluminum circuit board.

Example 1-1: Production of single-sided circuit board

Prepare an aluminum-clad substrate, the aluminum-clad substrate is a single-sided aluminum-clad substrate, including an insulating substrate layer and a front aluminum layer located on one side of the insulating substrate layer, and the other side of the insulating substrate layer has no aluminum layer, the insulating substrate layer forms a back solder resist layer 3 of the single-sided circuit board, the insulating substrate layer can use a PET film or a PI film, or other substrates known in the art, the insulating substrate layer and the front aluminum layer are combined by a well-known technology in the art, such as by bonding and pressing, which will not be repeated here;

Prepare anti-etching ink on the front aluminum layer (use PE10/S10B2 anti-etching ink purchased directly on the market) to cover the aluminum layer where the circuit and conductive line need to be formed. The position is completed during the circuit design stage, and then the designed circuit is printed on the front aluminum layer;

The aluminum-clad substrate is etched by etching to form a front aluminum circuit layer 1 and aluminum conductive wires 2, wherein the aluminum conductive wires 2 interconnect all the circuits of the front aluminum circuit layer 1. Etching to form circuits by etching is a well-known technique in the art, and the etching solution and specific processes are not described in detail here. The purpose of interconnecting all the circuits of the front aluminum circuit layer 1 by the aluminum conductive wires 2 is to enable the front aluminum circuit layer 1 to be energized during the electroplating stage, so that the tin-philic metal in the electrolyte can be deposited on the aluminum layer.

A 2% NAOH solution is used to remove the anti-etching ink to expose the covered aluminum layer, thereby obtaining a front aluminum circuit layer 1 and an aluminum conductive wire 1. The anti-etching ink can be removed by using a 10% ammonia solution. As shown in FIG. 1 to FIG. 1-3, a front aluminum circuit layer 1 formed after etching is obtained. The front aluminum circuit layer 1 includes a plurality of circuits 11. There are gaps between adjacent circuits 11 in the up and down directions shown in FIG. 1 to FIG. 1-1-1. There are aluminum conductive wires 2 between adjacent circuits. The aluminum conductive wires 2 interconnect the adjacent circuits, and interconnection and conduction of all circuits are achieved through the plurality of aluminum conductive wires 2.

A front solder resist layer 4 is made on the front aluminum circuit layer 1. The front solder resist layer 4 uses solder resist ink. The front solder resist layer 4 can be bonded by an adhesive and pressed on the front aluminum circuit layer 1. The front solder resist layer 4 has a pad window to partially cover the front aluminum circuit layer 1 to expose the aluminum pad 12. The aluminum pad 12 is used for soldering electronic components after being electroplated with a tin-philic metal; the front solder resist layer 4 also has a conductive wire window 41 to expose the aluminum conductive wire 2, as shown in Figures 2 to 2-3;

Anti-plating ink 5 (LB-1600D ink produced by Dongguan Lanbang Electronic Hardware Materials Co., Ltd.) is printed at the conductive wire window, as shown in FIG. 3 to FIG. 3-3. The anti-plating ink is used to prevent the aluminum conductive wire 2 from being electroplated with tin-philic metal during the electroplating process, so as to prevent the tin-philic metal from being difficult to corrode and dissolve and remove in a low-cost manner. If the tin-philic metal cannot be removed, the aluminum conductive wire 2 will interconnect the adjacent circuits 11, and the front aluminum circuit layer 1 will be short-circuited;

The tin-philic metal is plated on the aluminum pad by electroplating to obtain the tin-philic metal layer 6. A copper rod is selected as the anode for electroplating. Metal copper is plated on the aluminum pad 12. Since the surface of the aluminum conductive wire 2 is printed with anti-electroplating ink, copper ions will not be deposited on the aluminum conductive wire 2 and the anti-electroplating ink. Referring to FIG4-1, a cross-sectional view of the position of the aluminum pad 12 is shown. A group of aluminum pads 12 includes two left and right aluminum pads for adapting the positive and negative soldering feet of the component. Referring to FIG4-2, after electroplating, a tin-philic metal layer 6, i.e., a copper layer, is deposited on the aluminum pad 12 to form a copper pad. When soldering electronic components, solder paste is applied on the copper pad. During the reflow soldering process, the solidified tin has a good bonding force with the copper pad, and the electronic components are electrically connected reliably and are not easy to fall off.

The single-sided circuit board after the electroplating process is treated with a 10% concentration of NAOH solution. NAOH corrodes the anti-plating ink 5 and the aluminum conductive wire 2 covered by it, thereby disconnecting the aluminum conductive wire 2. There is no aluminum conductive wire interconnection between adjacent circuits 11, and no short circuit occurs. For details, see Figures 5 to 5-7, where a fracture 14 is formed at the disconnection position.

Example 1-2: Production of single-sided circuit board

The difference from Example 1 is that: when making the front solder resist layer 4, there is no need to make the conductive wire window 41 on the front solder resist layer 4, and the aluminum conductive wire 2 is covered by the front solder resist layer 4, so there is no printing anti-plating ink process; in the electroplating process, a silver rod is selected as the electroplating anode, and metallic silver is electroplated on the aluminum pad 12. After the electroplating process is completed, on the roll-to-roll punching machine, a punching die 7 with a ejector as shown in Figure 6 is used to punch the position of the aluminum conductive wire 2. Specifically, the punching die 7 includes an upper die 71 and a lower die 72. The upper die 71 is formed by a punching die 72, and the lower die 72 is formed by a punching die 71. 71 is provided with an ejector pin 73, and a clearance hole is provided on the lower mold 72 at a position corresponding to the ejector pin. After the circuit board is placed on the punching mold 7 and positioned, the mold is closed, and the ejector pin 73 punches off the aluminum conductive wire 2 and the front solder resist layer 4 and the back solder resist layer 3 at the position corresponding to the aluminum conductive wire 2, so as to disconnect the aluminum conductive wire 2, wherein a punching hole 8 is formed at the position where the aluminum conductive wire is punched off, and the punching hole 8 runs through the entire circuit board, as shown in Figures 5-4, 5-5, 5-10, and 5-11, and the fracture 14 is formed at the position where the punching hole 8 is located.

In other embodiments, the difference from Embodiments 1-2 lies in that a conductive wire window 41 is made on the front solder resist layer 4, but anti-plating ink is not printed, and during electroplating, a tin-philic metal layer 6 is plated on the aluminum conductive wire 2, and during the punching process, the aluminum conductive wire 2, the tin-philic metal layer 6, and the back solder resist layer 3 are punched out together to disconnect the aluminum conductive wire 2 and avoid a short circuit between adjacent wires 11 of the front aluminum circuit layer 1.

Example 2-1: Production of double-sided circuit board

Prepare an aluminum-clad substrate, which is a double-sided aluminum-clad substrate, including an insulating substrate layer and a front aluminum layer located on one side of the insulating substrate layer, and the other side of the insulating substrate layer is a back aluminum circuit layer 9. The insulating substrate layer forms an intermediate insulating layer 10 of the double-sided circuit board to insulate the front aluminum layer and the back aluminum layer. The insulating substrate layer can be made of PET film or PI film, or other substrates known in the art. The back of the back aluminum circuit layer 9 has been prefabricated with a back solder resist layer 3;

Make anti-etching ink on the front aluminum layer (the anti-etching ink is selected from the market directly purchased PE10/S10B2 anti-corrosion ink) is used to cover the aluminum layer where the circuit and conductive line need to be formed. The positions where the circuit and conductive line need to be formed are completed in the circuit design stage, and then the designed circuit is printed on the front aluminum layer;

The aluminum-clad substrate is etched by an etching method to form a front aluminum circuit layer 1 and aluminum conductive wires 2 by etching the front aluminum layer, wherein the aluminum conductive wires 2 interconnect all the circuits of the front aluminum circuit layer 1;

A 2% NAOH solution is used to remove the anti-etching ink to expose the covered aluminum layer, thereby obtaining a front aluminum circuit layer 1 and aluminum conductive wires 2; as shown in FIGS. 1 to 1-1-1, 1-4, and 1-5, a front aluminum circuit layer 1 formed after etching is obtained, wherein the front aluminum circuit layer 1 comprises a plurality of circuits 11, and adjacent circuits 11 are spaced apart in the up and down directions shown in FIGS. 1 to 1-1-1, and aluminum conductive wires 2 are provided between adjacent circuits, and the aluminum conductive wires 2 interconnect adjacent circuits, and interconnection and conduction of all circuits are achieved through the plurality of aluminum conductive wires 2;

A front solder resist layer 4 is made on the front aluminum circuit layer 1. The front solder resist layer 4 uses a solder resist cover film (PI cover film or PET cover film). The front solder resist layer 4 can be bonded and pressed on the front aluminum circuit layer 1 by an adhesive. The front solder resist layer 4 has a pad window, which partially covers the front aluminum circuit layer 1 to expose the aluminum pad 12. The aluminum pad 12 is used for soldering electronic components after being electroplated with a tin-philic metal; the front solder resist layer 4 also has a conductive wire window 41 to expose the aluminum conductive wire 2, as shown in Figures 2 to 2-1, and Figures 2-4 to 2-5;

Anti-plating ink 5 (LB-1600D ink produced by Dongguan Lanbang Electronic Hardware Materials Co., Ltd.) is printed at the conductive wire window 41, as shown in Figures 3 to 3-1, 3-4, and 3-5. The anti-plating ink is used to prevent the aluminum conductive wire 2 from being electroplated with tin-philic metal during the electroplating process, so as to prevent the tin-philic metal from being difficult to dissolve and remove in a low-cost manner. If the tin-philic metal cannot be removed, the aluminum conductive wire will interconnect adjacent circuits, and a short circuit will occur in the front aluminum circuit layer 1;

The tin-philic metal is electroplated on the aluminum pad by electroplating to obtain the tin-philic metal layer 6. The copper rod is used as the anode for electroplating, and the aluminum pad 12 is electroplated with metal copper. Since the surface of the aluminum conductive wire 2 is printed with anti-electroplating ink, copper ions will not be deposited on the aluminum conductive wire 2 and the anti-electroplating ink.

The single-sided circuit board after the electroplating process is treated with a 10% concentration of NAOH solution. NAOH corrodes the anti-plating ink 5 and the aluminum conductive wire 2 covered by it, thereby disconnecting the aluminum conductive wire 2. There is no aluminum conductive wire interconnection between adjacent circuits 11, and no short circuit occurs. For details, see Figures 5 to 5-5, 5-8, and 5-9, where a fracture 14 is formed at the disconnection position.

Example 2-2: Production of double-sided circuit board

The difference from Example 2-1 is that the back side of the insulating substrate layer of the aluminum-clad substrate is aluminum foil. In the etching process, the front aluminum layer and the back aluminum layer are etched together to form a front aluminum circuit layer 1 and a back aluminum circuit layer 9 respectively. In the solder resist layer making process, a front solder resist layer 4 is made on the front aluminum circuit layer 1, and a back solder resist layer 3 is made on the back aluminum circuit layer 9. There is no need to make a conductive wire window on the front solder resist layer 4. The aluminum conductive wire 2 is covered by the front solder resist layer 4, so there is no printing anti-electroplating ink process. In the electroplating process, a silver rod is selected as the anode for electroplating. The aluminum solder resist layer 4 is used as the anode for electroplating. Metallic silver is electroplated on the disk 12. After the electroplating process is completed, on a roll-to-roll punching machine, a mold with a ejector as shown in Figure 6 is used to punch out the aluminum conductive wire 2 and the corresponding front solder resist layer 4, the middle insulating layer 10, the back aluminum circuit layer 9 and the back solder resist layer 3 on the electroplated circuit board using the ejector to disconnect the aluminum conductive wire, wherein a punching hole 8 is formed at the location where the aluminum conductive wire is broken, and the punching hole 8 runs through the entire circuit board, as shown in Figures 5-4, 5-5, 5-12, and 5-13, and the fracture 14 is formed at the location of the punching hole 8.

Example 2-3: Production of double-sided circuit board

The difference from Example 2-1 is that: the aluminum-clad substrate is a single-sided aluminum-clad substrate, a front aluminum layer is provided on one side of the insulating substrate layer, and no aluminum layer is provided on the other side. After etching the front aluminum layer and before the electroplating process, the back aluminum circuit layer (prefabricated, specifically, in this embodiment, a single-sided aluminum-clad substrate is used for etching) is fixed to the insulating substrate layer of the aluminum-clad substrate by adhesive bonding to form a double-sided circuit board, and then the electroplating process is performed. It can be understood that the back aluminum circuit layer 9 can be bonded to the insulating substrate layer before removing the anti-etching ink, or can be bonded to the back aluminum circuit layer after removing the anti-etching ink and before making the front solder resist layer, or can be bonded to the back circuit layer after making the front solder resist layer. In this embodiment, it is preferred to combine the back aluminum circuit layer after removing the anti-etching ink, that is, in the etching stage, a portion of the single-layer aluminum-coated substrate is etched to form the front aluminum circuit layer, and a portion of the single-layer aluminum-coated substrate is etched to form the back aluminum circuit layer. Then, an adhesive is applied to the insulating substrate layer of the front aluminum circuit layer and/or the back aluminum circuit layer, and the adhesive is bonded and pressed together to combine the front aluminum circuit layer and the back aluminum circuit layer together, and the front solder resist layer and the back solder resist layer are manufactured at the same time to improve work efficiency.

For a double-sided circuit board, the back aluminum circuit layer 9 is generally used for the positive and negative electrodes of an external power supply. Of course, a pad can also be provided on the back aluminum circuit layer to solder electronic components. For this reason, in Examples 2-1 to 2-3, a pad hole 15 can be pre-fabricated by a puncher before being assembled into a double-sided circuit board (the pre-fabricated pad hole is a prior art and will not be described in detail here). The pad hole 15 penetrates the front solder resist layer 4 and the front solder resist layer 4. The aluminum circuit layer 1 and the intermediate insulating layer 10 make the back aluminum circuit layer 9 exposed in the pad hole 15. Before electroplating, an extrusion die is used to extrude the front aluminum circuit layer 1 and the back aluminum circuit layer 9 to form contact conduction (existing technology). During electroplating, the surface of the back aluminum circuit layer 9 in the pad hole is electroplated with a tin-philic metal. The contact conduction between the front aluminum circuit layer and the back aluminum circuit layer is achieved by an extrusion die, so that during the electroplating stage, the back aluminum circuit layer can form an interconnection conduction with the front aluminum circuit layer, so that the tin-philic metal ions in the electroplating solution can be deposited on the back aluminum circuit layer in the pad hole, so that when soldering electronic components, the soldering can be firm, as shown in Figure 8.

In Examples 1-1 to 2-3, after the aluminum conductive wire is disconnected, a masking ink 13 (a permanent plugging resin produced by Quanying Technology Co., Ltd.) is made at the disconnection point of the aluminum conductive wire 2 to cover the fracture 14 of the aluminum conductive wire 2. A portion of the masking ink 13 is stacked on the front solder resist layer 4, as shown in Figures 7 to 7-5. The masking ink 13 masks the disconnection position to improve the overall appearance of the entire circuit board.

In Examples 1-1 to 2-3, the anode may be replaced with a tin rod or a nickel rod. The tin-affinity metal for electroplating is tin or nickel, which also has good tin affinity and is low in cost.

It can be seen from the above-mentioned embodiments 1-1 to 2-3 that, by adding aluminum conductive wires 2 during circuit design, all circuits of the front aluminum circuit layer 1 are interconnected and connected by using the aluminum conductive wires 2. When the front solder resist layer 4 is made, the front solder resist layer 4 exposes the aluminum pad 12, and then the electroplating process is used to electroplate the tin-philic metal, so that only a layer of tin-philic metal is electroplated on the surface of the aluminum pad 12. Compared with the chemical plating in the prior art, the anode metal loses electrons to form metal ions during electroplating, and then obtains electrons on the surface of the cathode aluminum pad to form metal atoms deposited on the pad surface. The metal ion concentration in the solution is stable and consistent, the thickness of the electroplated layer is stable, and there is no external electroplating like chemical plating. The plating impurities brought by the reducing agent and the impurities of the side reaction products are not deposited in the plating layer, which ensures the good solderability of the metal pad after electroplating. Since there are no side reaction impurities in the waste etching liquid, the recovery process is relatively simple and low in cost. Compared with the copper-aluminum composite foil in the prior art, the present invention only has tin-philic metals such as copper or silver at the pad position, which is obviously lower in cost than the solution with a layer of copper on the entire circuit surface, and also solves the difficulty of etching two metals. The recovery and treatment of the waste electroplating liquid also becomes easier and lower in cost. While meeting the good solderability of the pad, the present invention greatly reduces the production cost of the circuit board, which is conducive to the circuit board and related products to obtain good market competitiveness.

The embodiment of the second aspect of the present invention provides a metal aluminum circuit board, comprising an insulating substrate layer, a front aluminum circuit layer 1 bonded to the insulating substrate layer, and a front solder resist layer 4 bonded to the front aluminum circuit layer 1. A pad window is provided on the front solder resist layer 4, and an aluminum pad 12 is formed at the pad window on the front aluminum circuit layer 1. A tin-philic metal layer 6 is bonded to the surface of the aluminum pad 12. The thickness of the tin-philic metal layer 6 is 1 micron-20 microns. The thickness of the tin-philic metal layer 6 can be achieved by controlling the electroplating time. If the tin-philic metal layer 6 is too thin, it will affect the bonding strength with the solder paste when soldering electronic components. If the tin-philic metal layer 6 is too thick, it will increase the cost. After testing, the thickness of the tin-philic metal layer 6 is preferably 1 micron-20 microns. The front aluminum circuit layer 1 includes a plurality of circuits 11, and at least some of the circuits 11 have fractures 14, and the fractures 14 penetrate the front solder resist layer 4 and the front aluminum circuit layer 1.

In some embodiments of the present invention, the aluminum conductive wire 2 is broken by a breaking mold 7, the fracture 14 penetrates the insulating substrate layer, the aluminum section at the fracture 14 and the section of the insulating substrate layer are located on the same knife-cut surface, and the side of the front aluminum circuit layer at the fracture is not blocked by the front solder resist layer 4; or the fracture 14 does not penetrate the insulating substrate layer, and the side of the front aluminum circuit layer at the fracture is not blocked by the front solder resist layer, as shown in Figures 5-6 to 5-9, the fracture is formed by corroding the front solder resist layer 4 and the aluminum wire 12 with an alkaline solution.

In order to improve the overall appearance of the circuit board, in some embodiments of the present invention, a shielding ink 13 is provided at the fracture 14, and the shielding ink 13 shields the aluminum side at the fracture. A part of the shielding ink is stacked on the front solder resist layer 4, as shown in Figures 7 to 7-5 for details.

In some embodiments of the present invention, the circuit board is a single-sided circuit board, and the insulating substrate layer forms a back solder resist layer 3, as shown in Figures 2-2, 2-3, 3-2, 3-3, 4-1, 4-2, 5-6, 5-7, 5-10, 5-11, 7-2, and 7-3; in other embodiments, the circuit board is a double-sided circuit board, including a back aluminum circuit layer 9 bonded to the insulating substrate layer, and the back aluminum circuit layer 9 is bonded to A back solder resist layer 3 is provided, and the front aluminum circuit layer 1 and the back aluminum circuit layer 9 are in contact and conductive. The contact and conductive method is to push the front aluminum circuit layer 1 and the back aluminum circuit layer 9 to contact and achieve conduction through a mold. The insulating substrate layer forms the middle insulating layer 10 of the double-sided circuit board, as shown in Figures 2-4, 2-5, 3-4, 3-5, 4-3, 4-4, 5-8, 5-9, 5-12, 5-13, 7-4, and 7-5.

In some embodiments of the present invention, for a double-sided circuit board on which a pad needs to be formed on the back aluminum circuit layer 9, a pad hole is also included, wherein the pad hole penetrates the front solder resist layer, the front aluminum circuit layer and the insulating substrate layer, and the back aluminum circuit layer is exposed in the pad hole to form a back aluminum pad, and the surface of the back aluminum pad is combined with a tin-philic metal layer, so that the aluminum pad on the back aluminum circuit layer is electroplated with the tin-philic metal layer, so that the solder It is firm and reliable when connecting electronic components.

In some embodiments of the present invention, the tin-philic metal is copper, tin, silver or nickel.

The third aspect of the present invention provides a circuit board module, including the metal aluminum circuit board described in any one of the embodiments of the second aspect, and electronic components are welded on the tin-philic metal layer, and the electronic components can be resistors, LEDs or others; it can be understood that the circuit board module is a lamp, a printer, a computer or a car, and can also be other products that require the use of a circuit board and are not mentioned in this article.

In the embodiment of the present invention, a tin-philic metal layer is combined on the surface of the aluminum pad, the thickness of the tin-philic metal layer is 1 micron-20 microns, the front aluminum circuit layer includes multiple circuits, at least some of the circuits have fractures, and the fractures penetrate the front solder mask layer and the front aluminum circuit layer. The circuit board can be electroplated with tin-philic metal using an electroplating process, so that only a layer of tin-philic metal is electroplated on the surface of the aluminum pad. Compared with the chemical plating in the prior art, during electroplating, the anode metal loses electrons to form metal ions, and then obtains electrons on the surface of the cathode aluminum pad to form metal atoms deposited on the pad surface. The metal ion concentration in the solution is stable and consistent, the thickness of the electroplated layer is stable, and there is no external reduction like chemical plating. The waste etching liquid does not contain impurities from side reactions, which ensures good solderability of the metal pad after electroplating. The waste etching liquid does not contain impurities from side reactions, so the recycling process is relatively simple and low-cost. Compared with the copper-aluminum composite foil in the prior art, the present invention only has tin-philic metals such as copper or silver at the pad position, which is obviously lower in cost than a solution in which the entire circuit surface has a layer of copper. It also solves the difficulty of etching two metals, and the recycling of waste electroplating liquid becomes easier and lower in cost. While meeting the requirement of good solderability of the pad, the present invention greatly reduces the production cost of the circuit board, which is conducive to the circuit board and related products to obtain good market competitiveness.

The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

A method for manufacturing a metal aluminum circuit board, characterized by comprising:

Preparing an aluminum-clad substrate, wherein the aluminum-clad substrate comprises an insulating substrate layer and a front aluminum layer located on one side of the insulating substrate layer;

Prepare an anti-etching ink on the front aluminum layer to cover the aluminum layer where circuits and conductive lines need to be formed;

Etching the aluminum-clad substrate by an etching method to form a front aluminum circuit layer and aluminum conductive wires by etching the front aluminum layer, wherein the aluminum conductive wires interconnect all the circuits of the front aluminum circuit layer;

Removal of etch-resistant ink;

A front solder resist layer is formed on the front aluminum circuit layer, and the front solder resist layer partially covers the front aluminum circuit layer to expose the aluminum pad;

Electroplating a tin-philic metal onto the aluminum pad using an electroplating method;

Disconnect the aluminum conductive wire.
According to the method for manufacturing a metal aluminum circuit board according to claim 1, it is characterized in that: the aluminum-clad substrate is a single-sided aluminum-clad substrate, a front aluminum layer is provided on one side of the insulating substrate layer, and there is no aluminum layer on the other side, and the circuit board is a single-sided circuit board; or, the aluminum-clad substrate is a double-sided aluminum-clad substrate, and also includes a back aluminum layer provided on the other side of the insulating substrate layer, and the circuit board is a double-sided circuit board.
According to the method for manufacturing a metal aluminum circuit board according to claim 2, it is characterized in that: the back aluminum layer is a back aluminum circuit layer, and the aluminum-clad substrate also includes a back solder resist layer arranged on the back aluminum circuit layer; or the back aluminum layer is aluminum foil, and in the etching process, the back aluminum foil is etched to form a back aluminum circuit layer, and in the solder resist layer manufacturing process, the back solder resist layer is manufactured on the back aluminum circuit layer at the same time.
According to the method for manufacturing a metal aluminum circuit board according to claim 2, it is characterized in that: the aluminum-clad substrate is a single-sided aluminum-clad substrate, a front aluminum layer is provided on one side of the insulating substrate layer, and there is no aluminum layer on the other side, and after the front aluminum layer is etched and before the electroplating process, the back aluminum circuit layer is fixed to the insulating substrate layer of the aluminum-clad substrate by an adhesive to form a double-sided circuit board.
A method for manufacturing a metal aluminum circuit board according to claim 2, 3 or 4, characterized in that: it also includes a pad hole, the pad hole penetrates the front solder resist layer, the front aluminum circuit layer and the insulating substrate layer, the back aluminum circuit layer is exposed in the pad hole, and before electroplating, an extrusion die is used to separate the front aluminum circuit layer and the insulating substrate layer. The back aluminum circuit layer is extruded to form contact conduction, and during electroplating, the surface of the back aluminum circuit layer in the pad hole is electroplated with a tin-philic metal.
According to the method for manufacturing a metal aluminum circuit board according to claim 1, it is characterized in that: after the electroplating process is completed, on a roll-to-roll punching machine, a mold is used to punch out the aluminum conductive wires on the electroplated circuit board to achieve the disconnection of the aluminum conductive wires, wherein a punching hole is formed at the punching position of the aluminum conductive wire, and the punching hole runs through the entire circuit board.
According to the method for manufacturing a metal aluminum circuit board according to claim 1, it is characterized in that: when making the solder mask layer, the aluminum conductive wire is exposed and the anti-plating ink is printed, and after the electroplating process is completed, the anti-plating ink is removed using an alkaline solution, and the alkaline solution simultaneously corrodes and disconnects the aluminum conductive wire.
A method for manufacturing a metal aluminum circuit board according to any one of claims 1-4 and 6-7, characterized in that: after the aluminum conductive wire is disconnected, shielding ink is made at the disconnection position of the aluminum conductive wire to shield the fracture of the aluminum conductive wire, and a part of the shielding ink is stacked on the front solder resist layer.
The method for manufacturing a metal aluminum circuit board according to claim 1 is characterized in that the tin-philic metal is copper, tin, silver or nickel.
The method for manufacturing a metal aluminum circuit board according to claim 1 is characterized in that the front solder resist layer is solder resist ink or solder resist covering film.
A metal aluminum circuit board, characterized in that it includes an insulating substrate layer, a front aluminum circuit layer bonded to the insulating substrate layer, and a front solder resist layer bonded to the front aluminum circuit layer, wherein a pad window is provided on the front solder resist layer, the front aluminum circuit layer forms an aluminum pad at the pad window, the surface of the aluminum pad is bonded to a tin-philic metal layer, the thickness of the tin-philic metal layer is 1 micron-20 microns, the front aluminum circuit layer includes a plurality of circuits, at least some of the circuits have fractures, and the fractures penetrate the front solder resist layer and the front aluminum circuit layer.
According to a metal aluminum circuit board according to claim 11, it is characterized in that: the fracture penetrates the insulating substrate layer, the aluminum section at the fracture and the section of the insulating substrate layer are located on the same knife-cut surface, and the side of the front aluminum circuit layer at the fracture is not blocked by the front solder resist layer; or the fracture does not penetrate the insulating substrate layer, and the side of the front aluminum circuit layer at the fracture is not blocked by the front solder resist layer.
According to a metal aluminum circuit board according to claim 11 or 12, it is characterized in that: a shielding ink is provided at the fracture, the shielding ink shields the aluminum side at the fracture, and a part of the shielding ink is stacked on the front solder resist layer.
According to claim 11, a metal aluminum circuit board is characterized in that: the circuit board is a single-sided circuit board, and the insulating substrate layer forms a back solder resist layer; or the circuit board is a double-sided circuit board, including a back aluminum circuit layer bonded to the insulating substrate layer, the back aluminum circuit layer is bonded to the back solder resist layer, and the front aluminum circuit layer and the back aluminum circuit layer are in contact and conductive.
According to a metal aluminum circuit board as described in claim 14, it is characterized by: it also includes a pad hole, the pad hole penetrates the front solder mask layer, the front aluminum circuit layer and the insulating substrate layer, the back aluminum circuit layer is exposed in the pad hole to form a back aluminum pad, and the surface of the back aluminum pad is combined with a tin-philic metal layer.
The metal aluminum circuit board according to claim 11 is characterized in that the tin-philic metal is copper, tin, silver or nickel.
A circuit board module, characterized in that it comprises the metal aluminum circuit board according to any one of claims 11 to 16, and electronic components are welded on the tin-philic metal layer.
A circuit board module according to claim 17, characterized in that the circuit board module is a lamp, a printer, a computer or a car.