Manufacturing method of circuit board, circuit board and lamp strip

Abstract

The invention discloses a manufacturing method of a circuit board, the circuit board and a lamp strip, the circuit board comprises main circuits, the main circuits are single-layer main circuits formed by copper-aluminum composite metal or aluminum, or the main circuits are double-layer main circuits formed by aluminum and copper or aluminum and copper-aluminum composite metal, the number of the main circuits is multiple, and the main circuits are arranged at the board edge position of the circuit board. The line widths of at least partial positions of the main line are different; the auxiliary circuit is made of copper or copper-aluminum composite metal, and the auxiliary circuit is located in the middle area of the circuit board; the thickness of part or all of the main circuit is greater than that of the auxiliary circuit; the circuit board comprises a non-metal area without a circuit, and in at least part of the non-metal area, the first insulating layer and the second insulating layer are bonded to clamp the main circuit and the auxiliary circuit. The thickness of a main circuit and a metal-free area are reduced, the load of the circuit board is improved, and wrinkling, large bumps and the like of the circuit board are avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of light strips, and in particular to a method for manufacturing a circuit board, a circuit board and a light strip. Background Art

[0002] LED light strips are very popular and widely circulated products. Their characteristic is that cost is king. Therefore, innovation to reduce the cost of popular and widely circulated products is the most important innovation. In product design, a refined cost structure must be matched. Therefore, in the composition design of the light strip circuit board, more aluminum will be used instead of copper to make the circuit on a circuit board. Another feature of the light strip circuit board is that there are at least two positive and negative main lines from beginning to end, which are used to connect the power supply to the LED of the entire light strip. The circuit board also includes a device for welding LEDs to form a series-parallel structure. The secondary line, in which the main line carries the entire light strip, requires wider and / or thicker metal for the main line. Therefore, the main line uses a large amount of metal. If copper is used, the cost is too high, so the main line uses aluminum or copper-aluminum composite metal, and the cost can be greatly reduced; since the secondary lines are very short and have a small current carrying capacity, a thinner and smaller circuit design can be adopted than the main line, so very thin metal can be used; but there are pads for soldering LEDs on the secondary lines. In order to have good solderability and low cost, the secondary lines are designed into very small circuits with very thin copper, and the cost is also lower, or the secondary lines use thinner copper-aluminum foil (a layer of copper is combined with the aluminum surface), which is even lower in cost.

[0003] In order to reduce the production cost of circuit boards, in the prior art, the main line uses two parallel wires of aluminum or copper-clad aluminum to reduce the use of copper in the main line. Aluminum is much cheaper than copper, which greatly reduces the production cost of circuit boards and achieves good market benefits.

[0004] During a long period of market research and development, the inventor discovered that the use of parallel wires in the main line would cause the following problems:

[0005] ①、For details, please refer to Figure 1.1 As shown, since the main circuit is two parallel wires 1' of equal width (equal width means that the width of a single wire is consistent everywhere), the width of each wire is the same from beginning to end, and the parallel wires are designed near the edge of the circuit board, and must be kept at a certain distance a' (at least 0.2mm) from the component pads on the circuit board. In the actual circuit, the distance from the edge of the circuit board to the component pad is limited, and many positions are as small as less than 1mm, which causes the parallel wires used to be very narrow. The parallel wires are the main positive and negative main wires from beginning to end. Narrow wires mean small load, causing the brightness of the tail end of the light strip to be much lower than that of the head end (the light strips are very long, generally ≥5 meters), and will also cause the parallel wires to heat up, shortening the life of the LED lamp;

[0006] ②. For a more scientific cost matching, the parallel wires 1' are all made of aluminum wire or copper-clad aluminum wire, and the secondary circuit 2' is made of copper foil. For cost optimization, the circuit formed by the copper foil will be designed as small as possible, and the amount of copper used will be small, so as to reduce the cost. This will cause the upper and lower circuit metals to occupy a small area of ​​the circuit board, that is, a large area of ​​metal-free area b' is formed in many positions in the circuit. Only the upper and lower layers of resin film are bonded together, so that when the circuit board is SMT soldered, it undergoes high-temperature reflow soldering of more than 200 degrees. The resin film shrinks greatly at the position without metal support in a large area, causing the circuit board to wrinkle, affecting the appearance of the light strip;

[0007] ③. For details, please refer to Figure 1.2 , Figure 1.3 As shown, since parallel wires are arranged in a very small space near the edge of the circuit board, and the wires are narrow, the parallel wires need to be made thicker to have a larger load to meet the requirement that there is no obvious brightness difference between the beginning and the end of the light strip. However, when the parallel wires are too thick, the entire circuit board is too thick on both sides and too thin in the middle, so that when the SMT reflow soldering components, the circuit board will be deformed under high temperature; at the same time, the parallel wires are too thick, resulting in bubbles 3' on the sides of the parallel wires. During reflow soldering, the temperature is too high, and the bubbles expand thermally to form large bulges 4', which eventually make the light strip product scrapped.

[0008] To this end, it is necessary to improve and optimize existing circuit boards, etc. Summary of the invention

[0009] The present invention aims to solve at least one of the problems of the prior art. To this end, the present invention provides a method for manufacturing a circuit board, a circuit board and a light strip, which are conducive to reducing the thickness of the main circuit and the metal-free area, increasing the load of the circuit board, and avoiding wrinkling and forming a large bulge on the circuit board.

[0010] The technical solution adopted by the present invention to solve its technical problem is:

[0011] In a first aspect, an embodiment of the present invention provides a method for manufacturing a circuit board, comprising:

[0012] providing a first insulating film;

[0013] Bonding a first metal foil to the first insulating film, die-cutting the first metal foil using a die-cutting method, tearing off unnecessary metal, and forming a first circuit group with the metal remaining on the first insulating film, wherein the first circuit group has a plurality of circuits, and the first circuit group has at least two main circuits, and each main circuit has at least a portion of different widths;

[0014] Providing a second insulating film, bonding a second metal foil on the second insulating film, tearing off unnecessary metal after die-cutting, and the metal remaining on the second insulating film forms a second circuit group, wherein the second circuit group has a plurality of secondary circuits;

[0015] Laminating a first insulating film with a first circuit group and a second insulating film with a second circuit group together, so that the first insulating film and the second insulating film are bonded, and the first insulating film and the second insulating film sandwich the first circuit group and the second circuit group in the middle;

[0016] Wherein, the first metal foil is a copper-aluminum composite foil, and the second metal foil is a copper foil; or, the first metal foil is an aluminum foil, and the second metal foil is a copper foil or a copper-aluminum composite foil;

[0017] Wherein, the first insulating film and / or the second insulating film are die-cut to form a pad window.

[0018] Optionally, during bonding, the first circuit group and the second circuit group partially overlap or do not overlap; for a single pad window, the exposed metal is copper, aluminum, or copper and aluminum; among the multiple pad windows, the metal exposed in each pad window is the same or different.

[0019] Optionally, during bonding, the first circuit group and the second circuit group do not overlap, and a method for making a pad window is as follows: after providing a first insulating film, a pad window is made on the first insulating film by a die-cutting method; or / and, after providing a second insulating film, a pad window is made on the second insulating film by a die-cutting method; during bonding, the first circuit group and the second circuit group partially overlap, and a method for making a pad window is as follows: after providing a first insulating film, a pad window is made on the first insulating film by a die-cutting method; or / and, a pad window is made on the first insulating film with the first circuit group by die-cutting, and the pad window passes through the first insulating film, or, part of the pad window passes through the first insulating film, and part of the pad window passes through the first insulating film and the metal of the first circuit group; or / and, after providing the second insulating film, a pad window is made on the second insulating film by a die-cutting method.

[0020] In a first aspect, another embodiment of the present invention provides a method for manufacturing a circuit board, comprising:

[0021] providing a first insulating film;

[0022] Bonding a first metal foil to the first insulating film, die-cutting the first metal foil using a die-cutting method, tearing off unnecessary metal, and forming a first circuit group with the metal remaining on the first insulating film, wherein the first circuit group includes a plurality of first main circuits, and each first main circuit has at least a portion of a different width;

[0023] Providing a second insulating film, bonding a second metal foil on the second insulating film, tearing off unnecessary metal after die-cutting, and the metal remaining on the second insulating film forms a second circuit group, wherein the second circuit group includes a plurality of second main circuits and a plurality of auxiliary circuits;

[0024] Laminating a first insulating film with a first circuit group and a second insulating film with a second circuit group together, so that the first insulating film and the second insulating film are bonded, the first insulating film and the second insulating film sandwich the first main circuit, the second main circuit, and the auxiliary circuit in the middle, and the second main circuit overlaps and contacts the first main circuit for conduction;

[0025] Wherein, the first metal foil is aluminum foil; the second metal foil is copper foil or copper-aluminum composite foil;

[0026] Wherein, the first insulating film and / or the second insulating film are die-cut to form a pad window.

[0027] Optionally, the method for making the pad window is: using a die-cutting method to make a pad window on a first insulating film with a first circuit group, the pad window passes through the first insulating film, or part of the pad window passes through the first insulating film, and part of the pad window passes through the first insulating film and the metal of the first circuit group; or / and, after providing a second insulating film, making a pad window on the second insulating film by die-cutting.

[0028] Optionally, for a single pad window, the exposed metal is copper, aluminum, or copper and aluminum; among the multiple pad windows, the metal exposed in each pad window is the same or different.

[0029] Optionally, there are two second main lines, which are arranged on both sides of the secondary line. The second main lines extend along the length direction of the circuit board, and the length of the second main lines is greater than 1 meter.

[0030] The first aspect of the present invention has at least one of the following beneficial effects: the present invention forms a first circuit group by bonding a first metal foil to a first insulating film, using a die-cutting method to die-cut the first metal foil, the first circuit group has at least two main circuits, each main circuit has at least partially inconsistent widths, bonding a second metal foil to a second insulating film, and die-cutting to form a second circuit group, the second circuit group has multiple secondary circuits, the first insulating film with the first circuit group and the second insulating film with the second circuit group are laminated together, so that the first insulating film and the second insulating film are bonded, and the first insulating film and the second insulating film sandwich the first circuit group and the second circuit group in the middle, wherein the first metal foil is a copper-aluminum composite foil, The second metal foil is a copper foil; or the first metal foil is an aluminum foil, and the second metal foil is a copper foil or a copper-aluminum composite foil; or the first metal foil is bonded to the first insulating film, and the first metal foil is die-cut to form a first circuit group by a die-cutting method, the first circuit group contains a plurality of first main circuits, and each of the first main circuits has at least a portion of different widths, and the second metal foil is bonded to the second insulating film, and the second circuit group is formed after die-cutting, the second circuit group contains a plurality of second main circuits and a plurality of secondary circuits, and the first insulating film with the first circuit group and the second insulating film with the second circuit group are bonded together, so that the first insulating film and the second insulating film are bonded, and the first insulating film and the second insulating film form the first main circuit, the second main circuit, and the secondary circuit. The first main circuit is sandwiched in the middle, and the second main circuit overlaps with the first main circuit to contact and conduct, wherein the first metal foil is aluminum foil; the second metal foil is copper foil or copper-aluminum composite foil; the prior art setting method of setting the main circuit as parallel wires of equal width is abandoned. In this embodiment, the width of at least part of the main circuit is inconsistent, so that the main circuit can be set to be different in width, and the width of the main circuit is no longer completely limited by the distance space from the edge of the circuit board to the component pad. Therefore, the load of the main circuit can be increased, and the problem of different brightness at the beginning and end of the light strip can be reduced or avoided. Since the width of at least part of the main circuit is large, it is not easy to cause the main circuit to heat up; since the width of the main circuit is different, the metal-free area in the circuit board can be significantly reduced, and the That is, the area where only the upper and lower layers of resin film are bonded together is reduced, and the resin film has metal support at more positions, so that when the circuit board is SMT soldered, the resin film will not have a significant shrinkage problem, and the problem of wrinkling of the circuit board and affecting the appearance of the light strip is solved; in this embodiment, the main circuits of different widths are compared with the parallel wires of medium width in the prior art, and the width of the main circuit is increased at least in some positions, which increases the load of the main circuit, so that the main circuit does not need to increase the thickness to increase the load, thereby avoiding the problem of the entire circuit board being too thick on both sides and too thin in the middle. Therefore, when the components are SMT reflow soldered, the circuit board is not easy to deform at high temperature, and it is not easy to form bubbles and large bulges, thereby improving the yield of the circuit board.

[0031] In a second aspect, an embodiment of the present invention provides a circuit board, including:

[0032] a first insulating layer;

[0033] A main line, wherein the main line is a single-layer main line formed of copper-aluminum composite metal or aluminum, or the main line is a double-layer main line formed of aluminum and copper, or aluminum and copper-aluminum composite metal. There are multiple main lines, which are arranged at the edge of the circuit board, and the line width of at least some positions of the main line is different;

[0034] A secondary circuit, the secondary circuit is copper or copper-aluminum composite metal, and the secondary circuit is located in the middle area of ​​the circuit board;

[0035] a second insulating layer;

[0036] The thickness of part or all of the main circuits is greater than the thickness of the secondary circuits; the circuit board includes a metal area with circuits and a non-metal area without circuits, and in at least part of the non-metal area, the first insulating layer is bonded to the second insulating layer, and the first insulating layer and the second insulating layer clamp the main circuit and the secondary circuit;

[0037] The pad window is arranged on the first insulating layer and / or on the second insulating layer.

[0038] Optionally, the main line is a long line greater than 1 meter, and the secondary line is a short line less than 1 meter.

[0039] Optionally, the main circuit is a double-layer main circuit, including a first main circuit formed of aluminum, and a second main circuit formed of copper or copper-aluminum composite metal, and the first main circuit and the second main circuit are at least partially overlapped, contacted and conductive.

[0040] Optionally, the second main lines are all long lines > 1 meter; the first main lines are long lines > 1 meter, or the first main line is divided into multiple sections, each section is longer than 1 meter, or at least some sections are less than 1 meter in length.

[0041] Optionally, the line width of at least some positions of the first main line is different.

[0042] Optionally, for a single pad window, the exposed metal is copper, aluminum, or copper and aluminum; among the multiple pad windows, the metal exposed in each pad window is the same or different.

[0043] Optionally, the minimum distance between the main circuit and the secondary circuit is a, where 0.1 mm≤a≤0.8 mm.

[0044] Optionally, the first insulating layer is a PET film or a PI film with glue, and the second insulating layer is a PET film or a PI film with glue; the materials of the first insulating layer and the second insulating layer are the same or different.

[0045] The second aspect of the present invention has at least one of the following beneficial effects: the present invention provides a single-layer main line formed of copper-aluminum composite metal or aluminum, or a double-layer main line formed of aluminum and copper, or aluminum and copper-aluminum composite metal, wherein there are multiple main lines arranged at the edge of the circuit board, the main line is a long line of >1 meter, and the line width of at least some positions of the main line is different; the secondary line is copper or copper-aluminum composite metal, the secondary line is located in the middle area of ​​the circuit board, and the secondary line is a short line of ≤1 meter; the thickness of some or all of the main lines is greater than the thickness of the secondary lines; the circuit board includes a metal area with a line, and a non-metal area without a line, and in at least part of the non-metal area, the first insulating layer is bonded to the second insulating layer, and the first insulating layer and the second insulating layer clamp the main line and the secondary line; the prior art method of setting the main line as parallel wires of equal width is abandoned. In this embodiment, the width of at least some positions of the main line is inconsistent, so that the main line can be set to different widths, and the width of the main line It is no longer completely limited by the distance space from the edge of the circuit board to the component pad. Therefore, the load of the main circuit can be increased, and the problem of uneven brightness at the beginning and end of the light strip can be reduced or avoided. Since the width of the main circuit is relatively large at least in some positions, it is not easy to cause the main circuit to heat up; since the main circuit is of different widths, the metal-free area in the circuit board can be significantly reduced, that is, the area where only the upper and lower layers of resin film are bonded together is reduced. The resin film has metal support at more positions, so that when the circuit board is SMT soldered, the resin film will not have a significant shrinkage problem, which solves the problem of wrinkling of the circuit board and affecting the appearance of the light strip; in this embodiment, the main circuit of different widths increases the width of the main circuit at least in some positions relative to the parallel wires in the prior art, increases the load of the main circuit, and makes it unnecessary to increase the thickness of the main circuit to increase the load. Therefore, the problem of the entire circuit board being too thick on both sides and too thin in the middle will not occur, so that when the components are SMT reflow soldered, the circuit board is not easy to deform at high temperature, and it is not easy to form bubbles and large bulges, thereby improving the yield of the circuit board.

[0046] In a third aspect, an embodiment of the present invention provides an LED light strip, comprising the circuit board described in any one of the embodiments of the second aspect, wherein LED lamp beads are welded on the circuit board. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1.1 It is a schematic diagram of a circuit board with a main circuit of equal-width parallel conductors in the prior art (the position is convenient for displaying the circuit and the front film is hidden);

[0048] Figure 1.2 yes Figure 1.1 Schematic diagram of the cross-section structure at position AA (rotated 90° clockwise and enlarged after cutting);

[0049] Figure 1.3 yes Figure 1.2Schematic diagram of the structure bubble shown when it forms a large bulge after reflow soldering;

[0050] Figure 2.1 1 is a schematic diagram of a planar structure of a main circuit on a first insulating film in an embodiment of the present invention (pad windows have been made on the first insulating film, and part of the pad windows are blocked by the main circuit);

[0051] Figure 2.2 is a schematic diagram of a planar structure of a secondary circuit on a second insulating film in an embodiment of the present invention;

[0052] Figure 2.3 yes Figure 2.1 Flip down 180° and fit in Figure 2.2 Schematic diagram of the plane structure on the top;

[0053] Figure 2.4 yes Figure 2.3 A schematic diagram of the planar structure after hiding the first insulating film;

[0054] Figure 2.5 yes Figure 2.4 A schematic diagram of a planar structure of a first insulating film hidden therein;

[0055] Figure 2.6 yes Figure 2.3 Schematic diagram of the cross-sectional structure of the middle BB (enlarged after being cut open and rotated 90° clockwise);

[0056] Figure 2.7 yes Figure 2.6 Schematic diagram of the decomposition of

[0057] Figure 3.1 is a schematic diagram of a planar structure of a first main circuit on a first insulating film in another embodiment of the present invention (pad windows have been made on the first insulating film, wherein some pad windows penetrate the first insulating film at positions other than the first main circuit, some pad windows penetrate the first insulating film and the first main circuit at positions of the first main circuit, and some pad windows only penetrate the first main circuit at positions of the first main circuit (these pad windows are blocked by the first main circuit));

[0058] Figure 3.2 is a schematic diagram of a planar structure of a second main circuit and a secondary circuit on a second insulating film in another embodiment of the present invention;

[0059] Figure 3.3 yes Figure 3.1 Flip down 180° and fit in Figure 3.2 Schematic diagram of the plane structure on the top;

[0060] Figure 3.4 yes Figure 3.3 A schematic diagram of the planar structure after hiding the first insulating film;

[0061] Figure 3.5yes Figure 3.4 A schematic diagram of a planar structure of a first insulating film hidden therein;

[0062] Figure 3.6 yes Figure 3.3 Schematic diagram of the cross-sectional structure of the CC (enlarged after being cut open and rotated 90° counterclockwise);

[0063] Figure 3.7 yes Figure 3.6 Schematic diagram of the decomposition of

[0064] Description of Figure Numbers:

[0065] 1-first insulating film, 2-main circuit, 21-first main circuit, 22-second main circuit, 3-second insulating film, 4-secondary circuit, 5-pad window, 51-scissor position pad, 52-lamp bead pad, 53-test pad, 10-glue. DETAILED DESCRIPTION

[0066] 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.

[0067] Many different implementations or examples are provided below for implementing the structure of the present invention.

[0068] The embodiment of the first aspect of the present invention provides a method for manufacturing a circuit board, including: providing a first insulating film 1, the first insulating film 1 is a film with glue 10, the first insulating film 1 is a PET film with glue, and can also be a PI film with glue; bonding a first metal foil to the first insulating film 1 with glue, the first metal foil is a copper-aluminum composite foil, the use of the copper-aluminum composite foil not only meets the requirements of the circuit board soldering, but also reduces the cost of aluminum, the first metal foil can also be aluminum foil, in the subsequent use of the circuit board, a special solder paste that can solder aluminum can be selected; using a die-cutting method to die-cut the first metal foil, tear off unnecessary metal, and the metal remaining on the first insulating film 1 forms a first circuit group, the first circuit group is multiple, and there are at least two main circuits 2 in the first circuit group. In this embodiment, the first circuit group is two continuously extended main circuits 2. The width of each main circuit 2 is inconsistent at least in some positions, that is, for a single main circuit 2, its width may have different widths at different positions, and the width is not consistent at any position. Therefore, the two main circuits will not form parallel wires of equal width, see Figure 2.1As shown, the main line 2 has 3 repeating units from left to right, and the width of a single main line in each unit is consistent in some positions and different in some positions; in actual production, the main line 2 can have dozens of repeating units from left to right to meet the line length requirements. Provide a second insulating film 3, the second insulating film 3 is a film with glue 10, the second insulating film 3 can be a PET film with glue, or a PI film with glue, the second insulating film 3 can be the same material as the first insulating film 1, for example, both use PI film with glue, or it can be different from the material of the first insulating film 1, for example, the first insulating film 1 uses a PET film with glue, and the second insulating film 3 uses a PI film with glue, and a second metal foil is bonded to the second insulating film 3. When the first metal foil is a copper-aluminum composite foil, the second metal foil is copper foil. When the first metal foil is aluminum foil, the second metal foil can be copper foil or copper-aluminum composite foil. After the second metal foil is die-cut, the unnecessary metal is torn off, and the metal remaining on the second insulating film 3 forms a second circuit group. There are multiple secondary circuits 4 in the second circuit group. The secondary circuits are mainly used for welding components, such as LED lamp beads and resistors; the first insulating film 1 with the first circuit group and the second insulating film 3 with the second circuit group are bonded together, and a mold is used for alignment during bonding. When bonding, a set pressure and temperature are applied, so that the first insulating film 1 and the second insulating film 3 are bonded by the above-mentioned glue 10. Thus, the first insulating film 1 and the second insulating film 3 clamp the first circuit group and the second circuit group in the middle to form a circuit board. In the above-mentioned production process, it is also necessary to use a die-cutting method to die-cut the first insulating film 1 and / or the second insulating film 3 to form a pad window so as to expose the metal pad. The production of the pad window 5 will be described in detail below.

[0069] In some embodiments of the present invention, when the first insulating film 1 with the first circuit group and the second insulating film 3 with the second circuit group are attached together, there are two solutions. Solution 1: The first circuit group and the second circuit group do not overlap. For details, see Figure 2.4 As shown; Solution 2: The first circuit group and the second circuit group can partially overlap. For example, when the second metal foil is die-cut, the second metal foil can be retained at the set scissor position pad 51 position, and the second metal foil overlaps with the main circuit 2 at the scissor position pad position. At this time, the second metal foil on the scissor position pad 51 overlaps with the main circuit, and the second metal foil at this position forms a part of the main circuit; according to the different positions of the pad windows, for a single pad window 5, the exposed pad metal can be copper, aluminum, or copper and aluminum. There are multiple pad windows on the circuit board, and the metal exposed in each pad window 5 can be the same, such as copper, or different, such as some pad metals are copper and some pad metals are aluminum. For details, see Figure 2.3As shown, the metal of the scissor pad 51 is the copper on the surface of the first metal foil, that is, the copper-aluminum composite metal, and the metal of the lamp bead pad 52 is partly the copper of the second metal foil and partly the copper (or aluminum) on the first metal foil; Figure 2.3 A pad window can also be opened on the back side (i.e., the second insulating film 3) so that the pad metal exposed in the back pad window is the aluminum on the first metal foil. The pad on the back side can be used as a test pad. During testing, you only need to press the test needle on the aluminum in the pad window to turn on the power.

[0070] See Figure 2.1-Figure 2.7 As shown, in some embodiments of the present invention, when bonding, the first circuit group and the second circuit group do not overlap, and the method for making the pad window is: after providing the first insulating film 1, the pad window 5 is made on the first insulating film 1 by a die-cutting method, that is, when the first metal foil is not bonded, the pad window is first made by a die-cutting method according to the circuit and pad design requirements, and then Figure 2.1 In the structure shown, after the pad window is made, the first metal foil is bonded to cover part of the pad window, and then the first metal foil is die-cut to form a first circuit group ( Figure 2.1 In some embodiments, the first metal foil has been die-cut to form a main circuit); in other embodiments, after providing the second insulating film 3, before bonding the second metal foil, a pad window 5 is made on the second insulating film 3 by die-cutting; in other embodiments, a part of the pad window is made on the first insulating film 1, and a part of the pad window is made on the second insulating film 3, that is, the pad window can be set on the first insulating film 1 or the second insulating film 3 alone, or can be set on the first insulating film 1 and the second insulating film 3 at the same time; in some embodiments, when bonding, the first circuit group and the second circuit group partially overlap, and the method for making the pad window is: after providing the first insulating film 1, the pad window is made by die-cutting when the first metal foil is not bonded, as described above; or, the first insulating film 1 with the first circuit group can also be made into a pad window by die-cutting, and the pad window penetrates the first insulating film. At this time, the pad metal exposed in the pad window is the second metal foil metal, or as Figure 2.1 , Figure 2.3As shown, the metal exposed in part of the pad is the first metal foil, and the metal exposed in part of the pad is the second metal foil; in other embodiments, the pad window is made by a die-cutting method on a first insulating film with a first circuit group, so that part of the pad window penetrates the first insulating film 1, and part of the pad window penetrates the first insulating film 1 and the metal of the first circuit group. This manufacturing method can also make the pad metal exposed in the pad window all the second metal foil, or part of the second metal foil and part of the first metal foil; in other embodiments, the pad window is made by a die-cutting method on the second insulating film 3 after providing a second insulating film 3. According to the position of the pad window relative to the first metal foil and the second metal foil, the pad metal exposed in the pad window can be the second metal foil or the first metal foil. Of course, it can also be that two kinds of metal foil are exposed in part of the pad window at the same time. For example, the pad window is set at the overlapping position of the first circuit group and the second circuit group, and half of the pad metal in the pad window is the second circuit group metal and half is the first circuit group metal.

[0071] See also Figure 2.1-Figure 2.3 The process of making the circuit board is as follows: Figure 2.1 The first insulating film 1 with the main line 2 and the pad window 5 is turned down 180 degrees so that the main line 2 faces the Figure 2.2 The secondary line 4 shown in the figure is then aligned and fitted to obtain Figure 2.3 The circuit board shown.

[0072] See Figure 3.1-Figure 3.7 The first embodiment of the present invention also provides another method for manufacturing a circuit board, including: providing a first insulating film 1, the first insulating film 1 is a film with glue 10, which can be a PET film with glue or a PI film with glue; bonding a first metal foil to the first insulating film 1, the first metal foil is aluminum foil, the cost of aluminum foil is significantly lower than that of copper foil, ensuring the low cost of the circuit board, using a die-cutting method to die-cut the first metal foil, tearing off unnecessary metal, and the metal remaining on the first insulating film 1 forms a first circuit group, the first circuit group contains a plurality of first main circuits 21, each of the first main circuits 21 has inconsistent widths at least in part, Figure 3.1 In the structure shown, the first line group is two first main lines 21; see Figure 3.2 As shown, a second insulating film 3 is provided, and the second insulating film 3 is a PI film with glue, or a PET film with glue, and a second metal foil is bonded on the second insulating film 3. The second metal foil is selected from copper foil, or copper-aluminum composite metal foil. After die-cutting, the unnecessary metal is torn off, and the metal remaining on the second insulating film 3 forms a second circuit group. The second circuit group includes multiple second main circuits 22 and a plurality of secondary circuits 4. Figure 3.2In the structure shown, there are two second main lines 22 and nine secondary lines 4; see Figure 3.3 As shown, the first insulating film 1 with the first circuit group and the second insulating film 3 with the second circuit group are attached together. Specifically, Figure 3.1 After the structure shown is turned downward by 180°, the first main line 21 faces Figure 3.2 The second main circuit 22 shown in the figure is then aligned and bonded together, so that the first insulating film 1 and the second insulating film 3 are bonded (specifically, the glue 10 on the two films is bonded), the first insulating film 1 and the second insulating film 3 clamp the first main circuit 21, the second main circuit 22, and the auxiliary circuit 4 in the middle, and the second main circuit 22 overlaps and contacts the first main circuit 21 for conduction; in this embodiment, different from Figure 2.1-Figure 2.7 The illustrated embodiments are: Figure 2.1-Figure 2.7 In the embodiment, the first metal foil is die-cut to form the main circuit 2, and the second metal foil is die-cut to form the secondary circuit 4. Figure 3.1-Figure 3.7 In the illustrated embodiment, the main circuit 2 is formed by a first main circuit 21 formed by die-cutting a first metal foil and a second main circuit 22 formed by die-cutting a second metal foil. Although the first metal foil is aluminum foil and has poor solderability (for ordinary solder paste), the second metal foil is copper foil or copper-aluminum composite foil, and the copper thereon has good solderability. The second main circuit 22 obtained by die-cutting the second metal foil can be conductive as long as it contacts the first main circuit 21 made of aluminum. The second main circuit 22 is exposed in the pad window to meet the solderability requirements. Therefore, in this embodiment, the main circuit 2 is cleverly divided into a first main circuit 21 made of aluminum and a second main circuit 22 made of copper (or copper-aluminum composite metal) to form a double-layer main circuit, thereby reducing the use of copper (relative to the main circuit being entirely made of copper), reducing the copper material used in the circuit board, and achieving the purpose of reducing the cost of the circuit board. The line width of at least part of each first main line 21 is different, which replaces the parallel wires of equal width in the prior art, improves the current carrying capacity of the main line, and helps to reduce the thickness of the main line under the same load, avoiding problems such as heat and bulging. The line width of at least part of each first main line 21 is different, which also reduces the non-metallic area on the circuit board.

[0073] It is understandable that, during the process of manufacturing the circuit board, it is also necessary to form a pad window 5 by die-cutting the first insulating film 1 or / and the second insulating film 3. In some embodiments of the present invention, the method for manufacturing the pad window is as follows: the first insulating film 1 with the first circuit group is die-cut to form a pad window 5, and the pad window 5 penetrates the first insulating film 1, so that after bonding, the metal of the second main circuit 22 originally covered by the first insulating film 1 is exposed to form a pad, and the position where the pad window penetrates the first insulating film 1 can also be the position where the first main circuit 21 is located, so that the aluminum on the first main circuit 21 is exposed in the pad window, and the pad can be used as a test pad 53. The test pad is used as a temporary pad, and the test requirements can be met by pressing the pad with a test needle; in other embodiments, part of the pad window 5 penetrates the first insulating film 1, and part of the pad window 5 penetrates the first insulating film 1 and the metal of the first circuit group, such as Figure 3.1 As shown; it can be understood that, after providing the second insulating film 3, a pad window can be made on the second insulating film 3 by die cutting; according to the different methods and positions of making the pad window, in some embodiments of the present invention, the pads exposed in the pad window 5 are all the second metal foil; in other embodiments, the pads exposed in part of the pad window 5 are the second metal foil, and the pads exposed in part of the pad window are the first metal foil, such as Figure 3.3 As shown, the first metal foil, i.e., aluminum (test pad 53), is exposed in the partial pad window; in other embodiments, the pad exposed in the partial pad window includes the first metal foil and the second metal foil, such as Figure 3.3 Therefore, for a single pad window 5, the exposed metal is copper or aluminum, or copper and aluminum, and among the multiple pad windows, the metals exposed in each pad window are the same or different.

[0074] In some embodiments of the present invention, there are two second main lines 22, which are arranged on both sides of the secondary line 4. The second main lines 22 extend along the length direction of the circuit board. The length of the second main line is greater than 1 meter. The second main line 22 is an uninterrupted long wire greater than 1 meter, which helps to improve the strength of the circuit board and prevent the circuit board from falling apart. It can be understood that the length of the second main line is not limited to greater than 1 meter, but is taken as a preferred embodiment.

[0075] From the above analysis, we can see that no matter Figure 2.1-Figure 2.7 The embodiment shown, or Figure 3.1-Figure 3.7The embodiments shown in the drawings all abandon the prior art method of setting the main circuit as parallel wires of equal width. In the present embodiment, the width of at least some positions of the main circuit is inconsistent, so that the main circuit can be set to have different widths. The width of the main circuit is no longer completely limited by the distance space from the edge of the circuit board to the component pad. Therefore, the load of the main circuit can be increased, and the problem of different brightness at the beginning and end of the light strip can be reduced or avoided. Since the width of at least some positions of the main circuit is large, it is not easy to cause the main circuit to heat up. Since the width of the main circuit is different, the metal-free area in the circuit board can be significantly reduced, that is, the area where only the upper and lower layers of resin films are bonded together can be reduced. In the present embodiment, the resin film has metal supports at more positions, so that when the circuit board is SMT soldered, the resin film will not have a significant shrinkage problem, which solves the problem of wrinkling of the circuit board and affecting the appearance of the light strip; in this embodiment, the main lines of varying widths increase the width of the main lines at least in some positions relative to the parallel wires in the prior art, thereby increasing the load of the main lines, so that the main lines do not need to increase the thickness to increase the load, thereby avoiding the problem of the entire circuit board being too thick on both sides and too thin in the middle, so that when the components are SMT reflow soldered, the circuit board is not easy to deform at high temperature, and is not easy to form bubbles and large bulges, thereby improving the yield of the circuit board.

[0076] A second aspect of the present invention provides a circuit board, comprising a first insulating layer corresponding to a first insulating film 1; a main circuit 2, wherein the main circuit 2 is a single-layer main circuit formed of a copper-aluminum composite metal or aluminum ( Figure 2.1-Figure 2.7 The main line 2 is a double-layer main line formed by aluminum and copper, or aluminum and copper-aluminum composite metal (corresponding to Figure 3.1-Figure 3.7In the embodiment shown in the figure, there are multiple main lines 2, which are arranged at the edge of the circuit board, and the line width of at least some positions of the main line 2 is different; the secondary line 4, the secondary line 4 is copper or copper-aluminum composite metal, the secondary line 4 is located in the middle area of ​​the circuit board, and the secondary line is used to weld LED lamp beads, resistors, etc.; the second insulating layer corresponds to the second insulating film 3, the thickness of part or all of the main line 2 is greater than the thickness of the secondary line 4, the main line 2 is used as the main line connecting the power supply to supply power to the numerous LED lamp beads on the circuit board, therefore, it is made thicker than the secondary line 4 to meet the current load requirements and avoid obvious brightness changes at the beginning and end of the light strip, and the secondary line 4 is only used for the LED lamp beads or / welded on the secondary line and resistor power supply, there are fewer LED lamp beads on each secondary circuit, and the current load requirement is low. Therefore, the secondary circuit can be made thin, saving metal materials and reducing costs; the circuit board includes a metal area with a circuit and a non-metal area without a circuit. In at least part of the non-metal area, the first insulating layer (first insulating film 1) is bonded to the second insulating layer (second insulating film 3), and the first insulating layer and the second insulating layer clamp the main circuit 2 and the secondary circuit 4; it can be understood that the first insulating layer and the second insulating layer are bonded by the glue 10 thereon; it also includes a pad window 5. From the above method embodiment, it can be seen that the pad window 5 can be set on the first insulating layer or / and the second insulating layer.

[0077] In some embodiments of the present invention, the main line 2 is set as a long line > 1 meter, and the secondary line 4 is set as a short line ≤ 1 meter.

[0078] See Figure 3.1-Figure 3.7As shown, in some embodiments of the present invention, the main circuit is a double-layer main circuit, including a first main circuit 21 formed of aluminum, and a second main circuit 22 formed of copper or copper-aluminum composite metal. The first main circuit 21 and the second main circuit 22 are at least partially overlapped, contacted and connected, so as to solve the problem that the aluminum soldering is poor and a special solder paste that can be soldered with aluminum is needed. Where the electronic components need to be soldered, the solder pad window can be opened at the position where the first main circuit 21 and the second main circuit 22 do not overlap, exposing the second main circuit 22 and the secondary circuit 4 made of copper or copper-aluminum composite metal. Copper is used for soldering, and the aluminum of the first main circuit 21 overlaps, contacts and is connected with the second main circuit 22, so that the secondary circuit can be powered by the second main circuit 22. The first main circuit 21 is made of aluminum, which greatly reduces the copper usage of the circuit board compared to copper, thereby reducing the manufacturing cost. In some embodiments of the present invention, the second main lines 22 are all long lines of >1 meter, thereby improving the strength of the circuit board and preventing it from falling apart; and the length of the first main line 21 is not limited. Specifically, the first main line is a long line of >1 meter, or the first main line is composed of multiple sections, each section is >1 meter long, or at least some sections are <1 meter long, that is, the first main line 21 can be a continuous long line greater than 1 meter, or it can be composed of multiple short lines of <1 meter.

[0079] like Figure 3.1-Figure 3.4 As shown, in some embodiments of the present invention, the first main line 21 serves as the main current load line, and the line width of at least some positions thereof is different, so as to reduce the thickness of the first main line 21, reduce the area of ​​the metal-free area on the circuit board, and reduce or eliminate the problem of large bulges. The second main line serves as an electrical connection between the first main line 21 and the secondary line 4, and the line widths thereof can be the same, or they can be designed to have different widths according to the circuit design.

[0080] In some embodiments of the present invention, as described in the method embodiment, for a single pad window 5, the exposed metal is copper, aluminum, or copper and aluminum; among the multiple pad windows 5, the metal exposed by each pad window 5 is the same or different.

[0081] Since the width of at least some parts of the main circuit 2 is different, in some embodiments of the present invention, the circuit board can be designed so that the minimum spacing between the main circuit 2 and the secondary circuit 4 is a, where 0.1mm≤a≤0.8mm, thereby reducing the area of ​​the metal-free area on the circuit board.

[0082] A third aspect of the present invention provides an LED light strip, comprising the circuit board described in any one of the embodiments of the second aspect, wherein LED lamp beads are welded on the circuit board.

[0083] The embodiments of the present invention are described in detail above with reference to 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

1. A method for manufacturing a circuit board, characterized in that: include: providing a first insulating film; Bonding a first metal foil to the first insulating film, die-cutting the first metal foil using a die-cutting method, tearing off unnecessary metal, and forming a first circuit group with the metal remaining on the first insulating film, wherein the first circuit group has a plurality of circuits, and the first circuit group has at least two main circuits, and each main circuit has at least a portion of different widths; Providing a second insulating film, bonding a second metal foil on the second insulating film, tearing off unnecessary metal after die-cutting, and the metal remaining on the second insulating film forms a second circuit group, wherein the second circuit group has a plurality of secondary circuits; Laminating a first insulating film with a first circuit group and a second insulating film with a second circuit group together, so that the first insulating film and the second insulating film are bonded, and the first insulating film and the second insulating film sandwich the first circuit group and the second circuit group in the middle; Wherein, the first metal foil is a copper-aluminum composite foil, and the second metal foil is a copper foil; or, the first metal foil is an aluminum foil, and the second metal foil is a copper foil or a copper-aluminum composite foil; Wherein, the first insulating film and / or the second insulating film are die-cut to form a pad window.

2. The method for manufacturing a circuit board according to claim 1, characterized in that: During bonding, the first circuit group and the second circuit group partially overlap or do not overlap; for a single pad window, the exposed metal is copper, aluminum, or copper and aluminum; among the multiple pad windows, the metal exposed in each pad window is the same or different.

3. A method for manufacturing a circuit board according to claim 2, characterized in that: During bonding, the first circuit group and the second circuit group do not overlap, and the method for making the pad window is: after providing a first insulating film, a pad window is made on the first insulating film by a die-cutting method; or / and, after providing a second insulating film, a pad window is made on the second insulating film by a die-cutting method; during bonding, the first circuit group and the second circuit group partially overlap, and the method for making the pad window is: after providing a first insulating film, a pad window is made on the first insulating film by a die-cutting method; or / and, the first insulating film with the first circuit group is die-cut to make a pad window, and the pad window passes through the first insulating film, or part of the pad window passes through the first insulating film, and part of the pad window passes through the first insulating film and the metal of the first circuit group; or / and, after providing the second insulating film, a pad window is made on the second insulating film by a die-cutting method.

4. A method for manufacturing a circuit board, characterized in that: include: providing a first insulating film; Bonding a first metal foil to the first insulating film - die-cutting the first metal foil using a die-cutting method, tearing off unnecessary metal, and the metal remaining on the first insulating film forms a first circuit group, wherein the first circuit group contains a plurality of first main circuits, and each first main circuit has a different width at least in part; Providing a second insulating film, bonding a second metal foil on the second insulating film, and tearing off unnecessary metal after die-cutting - the metal remaining on the second insulating film forms a second circuit group, wherein the second circuit group includes a plurality of second main circuits and a plurality of auxiliary circuits; Laminating a first insulating film with a first circuit group and a second insulating film with a second circuit group together, so that the first insulating film and the second insulating film are bonded, the first insulating film and the second insulating film sandwich the first main circuit, the second main circuit, and the auxiliary circuit in the middle, and the second main circuit overlaps and contacts the first main circuit for conduction; Wherein, the first metal foil is aluminum foil; the second metal foil is copper foil or copper-aluminum composite foil; Wherein, the first insulating film and / or the second insulating film are die-cut to form a pad window.

5. A method for manufacturing a circuit board according to claim 4, characterized in that: The method for making a pad window is as follows: using a die-cutting method to make a pad window on a first insulating film with a first circuit group, the pad window penetrates the first insulating film, or part of the pad window penetrates the first insulating film, and part of the pad window penetrates the first insulating film and the metal of the first circuit group; or / and, after providing a second insulating film, making a pad window on the second insulating film by die-cutting.

6. A method for manufacturing a circuit board according to claim 4, characterized in that: For a single pad window, the exposed metal is copper, aluminum, or copper and aluminum; among the multiple pad windows, the metals exposed in each pad window are the same or different.

7. The method for manufacturing a circuit board according to claim 4, characterized in that: There are two second main lines, which are arranged on both sides of the secondary line. The second main lines extend along the length direction of the circuit board. The length of the second main lines is greater than 1 meter.

8. A circuit board, characterized in that: include: a first insulating layer; A main line, wherein the main line is a single-layer main line formed of copper-aluminum composite metal or aluminum, or the main line is a double-layer main line formed of aluminum and copper, or aluminum and copper-aluminum composite metal. There are multiple main lines, which are arranged at the edge of the circuit board, and the line width of at least some positions of the main line is different; A secondary circuit, the secondary circuit is copper or copper-aluminum composite metal, and the secondary circuit is located in the middle area of ​​the circuit board; a second insulating layer; The thickness of part or all of the main circuits is greater than the thickness of the secondary circuits; the circuit board includes a metal area with circuits and a non-metal area without circuits, and in at least part of the non-metal area, the first insulating layer is bonded to the second insulating layer, and the first insulating layer and the second insulating layer clamp the main circuit and the secondary circuit; The pad window is arranged on the first insulating layer and / or on the second insulating layer.

9. A circuit board according to claim 8, characterized in that: The main line is a long line of more than 1 meter, and the secondary line is a short line of ≤ 1 meter.

10. A circuit board according to claim 8, characterized in that: The main circuit is a double-layer main circuit, including a first main circuit formed of aluminum, and a second main circuit formed of copper or copper-aluminum composite metal. The first main circuit and the second main circuit are at least partially overlapped, contacted and connected.

11. A circuit board according to claim 10, characterized in that: The second main lines are all long lines > 1 meter; the first main lines are long lines > 1 meter, or the first main line is divided into multiple sections, each section is longer than 1 meter, or at least some sections are less than 1 meter in length.

12. A circuit board according to claim 10, characterized in that: The line width of at least some positions of the first main line is different.

13. A circuit board according to claim 8, characterized in that: For a single pad window, the exposed metal is copper, aluminum, or copper and aluminum; among the multiple pad windows, the metals exposed in each pad window are the same or different.

14. A circuit board according to claim 8, characterized in that: The minimum distance between the main circuit and the secondary circuit is a, wherein 0.1 mm≤a≤0.8 mm.

15. A circuit board according to claim 8, characterized in that: The first insulating layer is a PET film or a PI film with glue, and the second insulating layer is a PET film or a PI film with glue; the materials of the first insulating layer and the second insulating layer are the same or different.

16. An LED light strip, characterized in that: A circuit board comprising any one of claims 8 to 15, wherein LED lamp beads are welded on the circuit board.

Images