Manufacturing method of bimetallic circuit board

Abstract

The invention discloses a manufacturing method of a bimetallic circuit board, which comprises a first conductor and a second conductor, the first conductor is cheaper than the second conductor, the adhesive force of the second conductor to an electronic component welding material is stronger than that of the first conductor, and the manufacturing method comprises the following steps of: 1) manufacturing a first circuit layer on the first conductor, and adhering the first circuit layer to a lower insulating layer; 2) manufacturing a second circuit layer on the second conductor, and manufacturing a bonding pad on the upper insulating layer; and (3) a first circuit layer and a second circuit layer are attached between the lower insulating layer and the upper insulating layer, so that the second circuit layer is exposed in the bonding pad area, and the first circuit layer and the second circuit layer are at least partially attached and electrically contacted. The first circuit layer and the second circuit layer are manufactured in advance, the first circuit layer and the second circuit layer are attached between the upper insulating layer and the insulating layer, and the second circuit layer is exposed at the position of the bonding pad; therefore, the material cost can be reduced, and the manufacturing process is simple and environment-friendly.

Description

Technical Field

[0001] The invention relates to a method for manufacturing a circuit board, and in particular discloses a method for manufacturing a bimetallic circuit board. Background Art

[0002] The circuit board of an existing LED light strip consists of a circuit layer, a lower insulating layer located on the back of the circuit layer, and an upper insulating layer located on the front of the circuit layer. The upper insulating layer has solder pads exposed at locations where electronic components are soldered. LED lamp beads or other electronic components can be soldered to the circuit layer via these pads. The circuit layer is typically made of copper foil because copper adheres well to the solder paste used to solder electronic components. However, copper is relatively expensive. To reduce costs, the industry has developed circuit layers made of copper-aluminum bimetallic materials. These bimetallic circuit layers have two structures. One is to completely wrap aluminum foil with copper foil, then roll it into copper-aluminum foil. A circuit pattern is then formed on the copper-aluminum foil, creating a circuit layer with aluminum as the inner core and copper as the outer surface. The other is to first create the circuit layer pattern using aluminum foil, then copper is plated on the surface of the aluminum circuit layer pattern, creating a circuit layer with aluminum as the base layer and copper as the outer layer. In this way, the exposed solder pad area is made of copper, suitable for soldering electronic components, while the inner core or base circuit layer is made of cheaper aluminum, reducing the material cost of the circuit layer. Although the existing copper-aluminum circuit layer reduces some material costs, it increases the complexity of the manufacturing process, and the total cost reduction is not obvious. Summary of the Invention

[0003] Based on this, it is necessary to provide a method for manufacturing a bimetallic circuit board that can reduce material costs and has a simple manufacturing process to address the existing technical problems.

[0004] To solve the problems of the prior art, the present invention discloses a method for manufacturing a bimetallic circuit board, comprising a first conductor and a second conductor, wherein the first conductor is cheaper than the second conductor, and the second conductor has stronger adhesion to electronic component solder than the first conductor. The manufacturing process comprises: step 1) forming a first circuit layer on the first conductor and adhering the first circuit layer to a lower insulating layer; step 2) forming a second circuit layer on the second conductor and forming a solder pad on the upper insulating layer; step 3) laminating the first circuit layer and the second circuit layer between the lower insulating layer and the upper insulating layer, so that the second circuit layer is exposed in the solder pad area, and the first circuit layer and the second circuit layer are at least partially attached and in electrical contact.

[0005] The beneficial effects of the present invention are as follows: since the first circuit layer and the second circuit layer are prefabricated and pressed between the upper insulating layer and the insulating layer, and the second circuit layer is exposed at the pad position, the material cost can be reduced and the manufacturing process can be simplified and environmentally friendly.

[0006] As a further improvement of the present invention:

[0007] In the step 1), a first conductor with a lower insulating layer adhered thereto is selected as a substrate, and a roller is used to die-cut a pattern of a first circuit layer on the first conductor, wherein the first circuit layer includes a main circuit and a connecting circuit; in the step 2), a second conductor with an upper insulating layer adhered thereto is selected as a substrate, and a roller is used to die-cut a pattern of a second circuit layer on the second conductor, and the solder pads are die-cut on the upper insulating layer using a roller, wherein the second circuit layer includes the same main circuit and connecting circuit as the first circuit layer; in the step 3), a hot press is used to bond the upper insulating layer to the lower insulating layer, and at the same time, the circuit of the second circuit layer is directly attached to the circuit of the first circuit layer so as to completely overlap.

[0008] In step 1), a first strip conductor is adhered to the lower insulating layer at predetermined intervals using a hot press, and the first conductor only forms a main circuit. In step 2), a second conductor adhered with an upper insulating layer is selected as a substrate, and a roller is used to die-cut a second circuit layer pattern on the second conductor. The second circuit layer includes only a connecting circuit, and the second circuit layer is provided with a connecting portion at a position where it needs to be electrically connected to the first circuit layer. The solder pad is die-cut on the upper insulating layer using a roller. In step 3), the upper insulating layer and the lower insulating layer are bonded using a hot press, and the connecting portion of the second circuit layer is attached to the first circuit layer and electrically connected thereto.

[0009] In step 1), the first circuit layer includes a main circuit and a connecting circuit; and the second circuit pattern in step 2) covers only the pad area. Specifically, in step 1), a first conductor with a lower insulating layer adhered thereto is selected as a substrate, and a roller is used to die-cut the pattern of the first circuit layer on the first conductor; in step 2), a second conductor with an upper insulating layer adhered thereto is selected as a substrate, and a roller is used to die-cut the second circuit pattern on the second conductor, and a roller is used to die-cut the pad on the upper insulating layer, so that the first circuit pattern only covers the pad; in step 3), a hot press is used to bond the upper insulating layer to the lower insulating layer, and the second circuit layer is directly attached to the first circuit layer. Alternatively, in step 1), a first conductor with a lower insulating layer adhered thereto is selected as a substrate, and a rolling cutter is used to die-cut a pattern of the first circuit layer on the first conductor; in step 2), a second conductor is first processed into a pattern that can cover the pad, and the second circuit layer is attached to a predetermined area of ​​the first circuit layer, and then a rolling cutter is used to die-cut the pad on the upper insulating layer; in step 3), a hot press is used to adhere the upper insulating layer to the first circuit layer, and the second circuit layer is exposed in the pad area of ​​the upper insulating layer.

[0010] The second circuit layer and the first circuit layer attachment area are bonded by using conductive adhesive.

[0011] The first conductor is aluminum, and the second conductor is copper. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1.1 This is a structural diagram of the first circuit layer of Example 1 of the present invention.

[0013] Figure 1.2 This is a structural diagram of the second circuit layer of Example 1 of the present invention.

[0014] Figure 1.3 This is a schematic structural diagram of the first circuit layer and the second circuit layer after bonding in Example 1 of the present invention.

[0015] Figure 1.4 for Figure 1.3 Schematic diagram of the structure of the AA section.

[0016] Figure 2.1 This is a structural diagram of the first circuit layer of Example 2 of the present invention.

[0017] Figure 2.2 This is a structural diagram of the second circuit layer of Example 2 of the present invention.

[0018] Figure 2.3 This is a schematic structural diagram of the first circuit layer and the second circuit layer after bonding in Example 2 of the present invention.

[0019] Figure 2.4 for Figure 2.3 Schematic diagram of the structure of the BB section.

[0020] Figure 3.1 This is a structural diagram of the first circuit layer of Example 3 of the present invention.

[0021] Figure 3.2 This is a structural diagram of the second circuit layer of Example 3 of the present invention.

[0022] Figure 3.3 This is a schematic structural diagram of the first circuit layer and the second circuit layer after bonding in Example 3 of the present invention.

[0023] Figure 3.4 for Figure 3.3 Schematic diagram of the structure of the CC section.

[0024] Figure 4 Schematic diagram of the manufacturing method of Example 1 of the present invention.

[0025] Figure 5 Schematic diagram of the manufacturing method of Example 2 of the present invention.

[0026] Figure 6This is one of the schematic diagrams of the manufacturing method of Example 3 of the present invention.

[0027] Figure 7 This is the second schematic diagram of the manufacturing method of Example 3 of the present invention.

[0028] Figure 8 The figure is a schematic diagram of the planar structure of an LED light strip using the circuit board of the present invention.

[0029] Figure 9 for Figure 8 Schematic diagram of the structure of the DD section. DETAILED DESCRIPTION

[0030] In order to further understand the features, technical means, specific purposes and functions of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The description of the positional relationship between the components themselves and the components in this application document (including but not limited to up, down, inside, outside, left, right, top and bottom, etc.) is only based on the relative relationship of the positions of the relevant components shown in the drawings of the present application, and does not represent an absolute limitation on the scope of protection of the present invention. Those skilled in the art should understand that if the direction of the component view changes, the description of the above positional relationship may change, but the essential relationship of its mechanical structure does not change.

[0031] Example 1, reference Figures 1.1 to 1.4. A bimetallic circuit board comprises a circuit layer 1, a lower insulating layer 2 arranged on the back of the circuit layer 1, and an upper insulating layer 3 arranged on the front of the circuit layer. The material of the lower insulating layer 2 is PI film or PET film, and the material of the upper insulating layer 3 is PI film or PET film or solder resist ink. The upper insulating layer 3 is provided with solder pads 30 exposing a local circuit layer at the position where the electronic components need to be soldered. The circuit layer 1 is classified in terms of material, including a first circuit layer 11 made of aluminum foil and a second circuit layer 12 made of copper foil; in terms of function, it includes a main circuit 1a and a connecting circuit 1b. The main circuit 1a is a circuit for conducting the total current of the circuit board, and the connecting circuit 1b is used to connect the main circuit 1a and each solder pad 31, that is, each electronic component. The first circuit layer 11 is adhered to the lower insulating layer 2, and includes the main circuit 1a and the connecting circuit 1b. The second circuit layer 12 also includes the same main circuit 1a and connecting circuit 1b as the first circuit layer 11. The second circuit layer 12 is directly attached to the first circuit layer 11 in a completely overlapping manner. The upper insulating layer 3 is adhered to the second circuit layer 12. Thus, the circuit layer exposed within the solder pads 30 of the upper insulating layer 3 is the second circuit layer 12. Direct attachment means that there is no insulator separating the two circuit layers, and the two are in direct electrical contact through the adhesive force of the upper and lower insulating layers. As a more preferred solution, a conductive adhesive can be applied between the two layers for bonding. The first circuit layer 11 can also be made of other materials that are less expensive than the second conductive layer 12, such as iron, and the second circuit layer 12 can also be made of materials that have good adhesion to solder paste used in electronic components, such as gold or silver.

[0032] The beneficial effects of the present invention are: since the second circuit layer is exposed in the pad area and the second circuit layer is made of a material such as copper that has good adhesion to the solder paste of the electronic components, it can provide good welding performance, and the first conductive layer is made of a conductor that is cheaper than the second conductive layer, which can reduce the material cost of the circuit layer; at the same time, since the first circuit layer and the second circuit layer are directly attached by utilizing the adhesion force of the upper and lower insulating layers, compared with the existing technology, the manufacturing process is simple and environmentally friendly.

[0033] Example 2, reference Figures 2.1 to 2.4 As a further improvement to Example 1, the first circuit layer 11 includes only the main circuit 1a, and the second circuit layer 12 includes only the connecting circuit 1b. The connecting circuit 1b is provided with a connecting portion 1c that overlaps with the main circuit 1a at the location where electrical connection with the main circuit 1a is required, and the connecting portion 1c is directly attached to the main circuit 1a. Because the main circuit 1a is used to transmit a relatively large total current, a larger cross-section, i.e., a thicker thickness, is typically required to reduce resistance. Using only inexpensive aluminum to manufacture the main circuit 1a can further reduce material costs.

[0034] Example 3, reference Figures 3.1 to 3.4As a further improvement to the present invention, the first circuit layer 11 includes the main circuit 1a and the connecting circuit 1b, and the second circuit layer 12 only covers the solder pad 30 area at the bottom of the upper insulating layer. In this way, both the main circuit 1a and the connecting circuit 1b are made of relatively inexpensive aluminum, while only the more expensive copper is used in the solder pad 30 area. This minimizes the use of material in the second circuit layer 12, thereby maximizing material cost savings.

[0035] The manufacturing method of Example 1, reference Figures 1.1 to 1.4 as well as Figure 4 A method for manufacturing a bimetallic circuit board: the first step is to produce a first circuit layer 11 and a second circuit layer 12. The first circuit layer 11 uses aluminum foil with a lower insulating layer 2 attached as the first substrate 110, and uses a first roller A1 to die-cut the main circuit 1a and the connecting circuit 1b on the aluminum foil of the first substrate 110, and the cutting waste is recycled through a first recycling drum A10; the second circuit layer 12 uses copper foil with an upper insulating layer 3 attached as the second substrate 120, and uses a second roller A2 to die-cut the solder pad 30 on the upper insulating layer 3 of the second substrate 120, and the die-cutting waste is recycled through a second recycling drum A20, and then uses a third roller A3 to die-cut the main circuit 1a and the connecting circuit 1b patterns identical to those of the first circuit layer 11 on the copper foil of the second substrate 120, and the die-cutting waste is recycled through a third recycling drum A30. In the second step, the aluminum foil of the first circuit layer 11 produced in the first step is facing upward, and the copper foil of the second circuit layer 12 is facing downward, and they are sent into the hot press R1 for pressing. Under the action of heat and pressure, the upper and lower insulating layers fill the cut-out areas on the circuit pattern and adhere to each other, so that the first circuit layer 11 and the second circuit layer 12 are directly attached and electrically contacted. In order to improve the reliability of the electrical contact between the first circuit layer 11 and the second circuit layer 12, conductive glue can also be applied before the two circuit layers are die-cut. In this way, when the two insulating layers are bonded, the two circuit layers are bonded by the conductive glue, which makes the electrical connection more reliable. Of course, the first circuit layer 11 and the second circuit layer 12 can also be formed into the circuit pattern by corrosion. The present invention prefers the die-cutting method, which has higher production efficiency and a more environmentally friendly production process.

[0036] The manufacturing method of Example 2, reference Figures 2.1 to 2.4 as well as Figure 5A method for manufacturing a bimetallic circuit board: the first step is to make a first circuit layer 11 and a second circuit layer 12. The first circuit layer 11 is made of aluminum strips 111 arranged at a certain interval, and then the aluminum strips 111 are adhered to the lower insulating layer 2 by a first hot press R1. The aluminum strips 111 constitute the main circuit 1a of the first circuit layer; the second circuit layer 12 uses a copper foil adhered with an upper insulating layer 3 as the second substrate 120, and a second roller A2 is used to die-cut the solder pads 30 on the upper insulating layer 3 of the second substrate 120. The die-cutting waste is recovered by a second recycling drum A20, and then a third roller A3 is used to die-cut the pattern of the connecting circuit 1b on the copper foil of the second substrate 120. The die-cutting waste is recovered by a third recycling drum A30. A connecting portion 1c overlapping with the main circuit 1a is provided on the connecting circuit 1b where it needs to be electrically connected to the main circuit 1a. In the second step, the aluminum foil of the first circuit layer 11 produced in the first step is facing upwards, and the copper foil of the second circuit layer 12 is facing downwards, and they are sent to the second hot press R2 for pressing. Under the action of hot pressing, the upper and lower insulating layers fill the area of ​​the conductor material cut out on the circuit pattern and adhere to each other, so that the connecting portion 1c of the second circuit layer 12 is attached to the first circuit layer 1a and electrically contacted. Similarly, in order to improve the reliability of the electrical contact between the connecting portion and the first circuit layer, a conductive glue can be applied before the two are attached. Similarly, the first circuit layer and the second circuit layer can also form the circuit pattern by corrosion. The present invention prefers a die-cutting method, which has higher production efficiency and a more environmentally friendly production process. The first conductive layer of this embodiment can also be manufactured using the method in Example 1, but the manufacturing process of this embodiment is simpler.

[0037] The manufacturing method of Example 3, refer to Figures 3.1 to 3.4 and Figure 6A method for manufacturing a bimetallic circuit board: the first step is to make a first circuit layer 11 and a second circuit layer 12. The first circuit layer 11 uses aluminum foil with a lower insulating layer attached as the first substrate 110, and uses a first roller A1 to die-cut the main circuit 1a and the connection circuit 1b on the aluminum foil of the first substrate 110, and the cutting waste is recycled through the first recycling bin A10; the second circuit layer uses copper foil with an upper insulating layer attached as the second substrate 120, and uses a second roller A2 to die-cut the second circuit layer 12 on the copper foil of the second substrate 120. The second circuit layer 12 only covers the area where the pad 30 needs to be die-cut later. Then, the pad 30 is die-cut on the upper insulating layer 3 corresponding to the position of the second circuit layer 12 by the third roller A3. The pad 30 area is slightly smaller than the second circuit layer 12, so that the copper foil can be adhered to the back of the upper insulating layer 3, and the die-cutting waste is recycled through the third recycling bin A30. In the second step, the aluminum foil of the first circuit layer 11 produced in the first step is facing upward, and the copper foil of the second circuit layer 12 is facing downward. These layers are then fed into a hot press R for pressing. Under the action of heat and pressure, the upper and lower insulating layers fill the areas where the conductive material has been removed from the two circuit layers and adhere to each other, so that the second circuit layer 12 is directly attached to the first circuit layer 11 and electrically contacts it. Similarly, to improve the reliability of the electrical contact between the second circuit layer 12 and the first circuit layer 11, a conductive adhesive may be applied before the two are attached. Similarly, the first circuit layer 11 and the second circuit layer 12 may also be formed into the circuit pattern by etching. The present invention preferably uses a die-cutting method, which is more efficient and environmentally friendly.

[0038] refer to Figures 3.1 to 3.4 and Figure 7 The second circuit layer 12 in Example 3 can also be realized by another method. The copper foil and the upper insulating layer 3 do not need to be pre-laminated. First, the second roller A2 is used to die-cut the pads 30 on the upper insulating layer 3, and a roller or punch is used to cut a copper foil sheet that can cover the pads 30 on the copper foil; then, a roller T is used to attach the copper foil sheet to a predetermined position on the first circuit layer 11 or to the pad 30 area on the back of the insulating layer 3; finally, the first circuit layer 11 and the upper insulating layer 3 are sent to the hot press R, and the hot press R attaches the upper insulating layer to the first circuit layer 11, and makes the pads 30 located on the copper foil sheet, that is, the second circuit layer 12.

[0039] The present invention uses a die-cutting machine to pre-fabricate the first circuit layer and the second circuit layer, and then uses a hot press to adhere the first circuit layer and the second circuit layer between the upper insulating layer and the insulating layer, with the second circuit layer exposed in the pad area. This can save material costs, simplify the manufacturing process, and be environmentally friendly.

[0040] refer to Figure 8 and Figure 9. An LED light strip using the above-mentioned bimetallic circuit board includes a circuit board, wherein the circuit board includes a circuit layer 1, a lower insulating layer 2 arranged on the back of the circuit layer 1, and an upper insulating layer 3 arranged on the front of the circuit layer 1. The circuit layer 1 is classified in terms of material, including a first circuit layer 11 made of aluminum foil and a second circuit layer 12 made of copper foil; classified in terms of function, including a main circuit 1a and a connecting circuit 1b. The second circuit layer 12 at least covers the area of ​​the soldering pad 30, and is at least partially directly attached to the first circuit layer 11. A soldering pad 30 is provided on the upper insulating layer 3. It also includes an LED lamp bead 4, and the LED lamp bead 4 includes at least a first lamp pin 41 and a second lamp pin 42, and the first lamp pin 41 and the second lamp pin 42 are soldered to the second circuit layer 12 through the soldering pad 30.

[0041] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for manufacturing a bimetallic circuit board, comprising a first conductor and a second conductor, wherein the first conductor is cheaper than the second conductor, and the second conductor has a stronger adhesion to electronic component solder than the first conductor, characterized in that include: Step 1) forming a first circuit layer on the first conductor and adhering the first circuit layer to the lower insulating layer; Step 2) forming a second circuit layer on the second conductor and forming a soldering pad on the upper insulating layer; Step 3) laminating the first circuit layer and the second circuit layer between the lower insulating layer and the upper insulating layer, so that the second circuit layer is exposed in the soldering pad area, and the first circuit layer and the second circuit layer are at least partially attached and in electrical contact.

2. The method for manufacturing a bimetallic circuit board according to claim 1, wherein: In the step 1), a first conductor with a lower insulating layer adhered thereto is selected as a substrate, and a roller is used to die-cut a pattern of a first circuit layer on the first conductor, wherein the first circuit layer includes a main circuit and a connecting circuit; in the step 2), a second conductor with an upper insulating layer adhered thereto is selected as a substrate, and a roller is used to die-cut a pattern of a second circuit layer on the second conductor, and the solder pads are die-cut on the upper insulating layer using a roller, wherein the second circuit layer includes the same main circuit and connecting circuit as the first circuit layer; in the step 3), a hot press is used to bond the upper insulating layer to the lower insulating layer, and at the same time, the circuit of the second circuit layer is directly attached to the circuit of the first circuit layer so as to completely overlap.

3. The method for manufacturing a bimetallic circuit board according to claim 1, wherein: In step 1), a first strip conductor is adhered to the lower insulating layer at predetermined intervals using a hot press, and the first conductor only forms a main circuit. In step 2), a second conductor adhered with an upper insulating layer is selected as a substrate, and a roller is used to die-cut a second circuit layer pattern on the second conductor. The second circuit layer includes only a connecting circuit, and the second circuit layer is provided with a connecting portion at a position where it needs to be electrically connected to the first circuit layer. The solder pad is die-cut on the upper insulating layer using a roller. In step 3), the upper insulating layer and the lower insulating layer are bonded using a hot press, and the connecting portion of the second circuit layer is attached to the first circuit layer and electrically connected thereto.

4. The method for manufacturing a bimetallic circuit board according to claim 1, wherein: In the step 1), the first circuit layer includes a main circuit and a connecting circuit; and the second circuit pattern in the step 2) only covers the pad area.

5. The method for manufacturing a bimetallic circuit board according to claim 4, wherein: In step 1), a first conductor with a lower insulating layer adhered thereto is selected as a substrate, and a roller is used to die-cut the pattern of the first circuit layer on the first conductor; in step 2), a second conductor with an upper insulating layer adhered thereto is selected as a substrate, and a roller is used to die-cut the second circuit pattern on the second conductor, and a roller is used to die-cut the pad on the upper insulating layer, so that the first circuit pattern only covers the pad; in step 3), a hot press is used to bond the upper insulating layer to the lower insulating layer, and the second circuit layer is directly attached to the first circuit layer.

6. The method for manufacturing a bimetallic circuit board according to claim 4, wherein: In step 1), a first conductor with a lower insulating layer adhered thereto is selected as a substrate, and a roller is used to die-cut the pattern of the first circuit layer on the first conductor; in step 2), a second conductor is first processed into a pattern that can cover the pad, and the second circuit layer is attached to a predetermined area of ​​the first circuit layer, and then a roller is used to die-cut the pad on the upper insulating layer; in step 3), a hot press is used to adhere the upper insulating layer to the first circuit layer, and the second circuit layer is exposed in the pad area of ​​the upper insulating layer.

7. The method for manufacturing a bimetallic circuit board according to claim 1, wherein: The second circuit layer and the first circuit layer attachment area are bonded by using conductive adhesive.

8. The method for manufacturing a bimetallic circuit board according to claim 1, wherein: The first conductor is aluminum, and the second conductor is copper.

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