Manufacturing method of double-layer circuit board, double-layer circuit board and LED lamp strip
By forming a through hole on the intermediate insulating film of the double-layer circuit board, and bonding the second circuit layer to the first insulating film to block the intermediate insulating film, the problem of tin holes during soldering is solved, and the yield rate is improved and the maintenance cost is reduced.
Patent Information
- Application Number
- CN202510135128.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-07
- Publication Date
- 2025-05-02
AI Technical Summary
Existing double-layer circuit boards are prone to tin holes or tin gaps when soldering, resulting in poor conduction and increasing the defective rate of lamp strip production and maintenance costs.
By forming a through hole on the intermediate insulating film of the double-layer circuit board, and bonding the second line layer to the first insulating film at some or all of the through holes, the second line layer blocks the intermediate insulating film, thereby avoiding the formation of tin holes.
Effectively reduce or avoid tin holes, improve the yield of circuit boards, and reduce maintenance costs.
Smart Images
Figure CN119922843A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a light strip, in particular to a method for manufacturing a double-layer circuit board, the double-layer circuit board and an LED light strip. Background Art
[0002] A double-layer circuit board has two layers of circuits, which are separated by an insulating layer. However, both layers of circuits need to be interconnected. One of the existing interconnection methods is as follows: After punching holes in the middle insulation layer, the upper circuit layer and the adhesive layer, they are pasted onto the back circuit; or after applying adhesive on the back of the single-sided copper clad laminate, punch holes and stick them onto the copper foil, and then etch to form two layers of circuits. Figure 1.1 As shown, the bottom of the bowl hole 1' made by the above two methods is the lower circuit metal 2', and the edge of the hole is the upper circuit metal 3'. When this board is used, solder paste is applied to the bowl hole and reflowed to solder the upper and lower metal layers together at the bowl hole. This method has been promoted and used by the inventor in the circuit board industry, especially for the production of light strip circuit boards. It has been mass-produced for more than ten years. However, there has always been a serious defect that the tin on the bowl hole is not full, or tin voids are formed after tinning the bowl hole. Figure 1.2 As shown, there is a tin cavity 5' under the tin 4', which makes a lot of bowl holes not conductive after SMT soldering and requires manual repair to make them conductive. For details, see Figure 1.3 As shown, even after soldering the component foot 6', the metal of the upper and lower layers of circuits cannot be connected; some bowl holes are invisible because they are wrapped in tin cavities, and at the same time, a small amount of tin connects the upper and lower layers of circuits. However, when the lamp belt reaches the user, the conduction fails if it is slightly bent, and the LED light does not light up.
[0003] The inventors have found that the reason for the poor conductivity of the bowl holes and the tin voids is that the intermediate insulating material 7' of the bowl hole wall repels tin, resulting in tin voids or tin gaps. Even if the lower metal layer is pushed to the bowl hole and is flush or nearly flush with the upper metal layer, there is still a gap between the upper and lower metal layers. In particular, there are often tolerances when the mold is pushed, and the pushing is not accurate, the gap is larger, and the upper and lower metal layers cannot be guaranteed to be 100% effectively connected after soldering. Moreover, generally a light strip is at least 5 meters long, and there are at least hundreds of bowl holes that need to be soldered for conduction. The actual situation is that every light strip has poor soldering of the bowl holes during production, and they need to be repaired, resulting in a high defective rate of light strip production and high maintenance costs. Summary of the Invention
[0004] The present invention aims to solve at least one of the problems in the prior art. To this end, the present invention provides a method for manufacturing a double-layer circuit board, a double-layer circuit board, and an LED light strip, which can avoid tin voids and improve the yield rate.
[0005] The technical solution adopted by the present invention to solve its technical problem is: In a first aspect, an embodiment of the present invention provides a method for manufacturing a double-layer circuit board, comprising: On the first insulating film with glue, a conductive wire is attached to form a first circuit layer; or, a metal foil is attached, and after die-cutting, unnecessary metal is removed to form the first circuit layer; Die-cut the intermediate insulating film with adhesive on both sides to form conductive holes; The metal foil is attached to the intermediate insulating film, and then the metal foil is die-cut and the unnecessary metal is removed to form the second circuit layer; Die-cut the second insulating film with glue on the top layer to form a pad window; After aligning and laminating the first insulating film with the first circuit layer, the intermediate insulating film with the second circuit layer, and the second insulating film with the pad window, they are hot-pressed into a circuit board, so that the second circuit layer is bonded to the first insulating film at some or all of the conductive holes.
[0006] In the first aspect, another embodiment of the present invention further provides a method for manufacturing a double-layer circuit board, comprising: On the first insulating film with glue, a conductive wire is attached to form a first circuit layer; or, a metal foil is attached, and after die-cutting, unnecessary metal is removed to form the first circuit layer; Die-cut the intermediate insulating film with adhesive on both sides to form conductive holes; A protective film is applied to one side of the intermediate insulating film and a metal foil is applied to the other side. After hot pressing, the metal foil on the intermediate insulating film is etched using an etching method to obtain a second circuit layer, and then the protective film is torn off; Aligning and laminating the first insulating film with the first circuit layer and the intermediate insulating film with the second circuit layer, and then subjecting them to heat pressing treatment, so that the second circuit layer is bonded to the first insulating film at some or all of the via holes; Make an ink solder mask layer on the second circuit layer.
[0007] The first aspect of the present invention has at least one of the following beneficial effects: In an embodiment of the present invention, a first insulating film with a first circuit layer, an intermediate insulating film with a second circuit layer, and a second insulating film with a pad window are aligned and laminated, and then hot-pressed to form a circuit board, so that the second circuit layer is bonded to the first insulating film at some or all of the via holes; or, a first insulating film with a first circuit layer and an intermediate insulating film with a second circuit layer are aligned and laminated, and then hot-pressed, so that the second circuit layer is bonded to the first insulating film at some or all of the via holes. As a result, the two layers of metal circuits are close to, in contact with, or overlap at some or all of the via holes, and the second circuit layer partially blocks the intermediate insulating film in the via holes. Therefore, when soldering the circuit board, the intermediate insulating material blocked by the second circuit layer does not repel tin, and the tin can flow smoothly to the two layers of circuit metal, reducing or avoiding tin voids and effectively improving the yield of the circuit board.
[0008] In a second aspect, an embodiment of the present invention provides a double-layer circuit board, comprising: The first insulating film is a back solder resist layer; A first circuit layer is bonded to the first insulating film. The first circuit layer comprises circuits of uniform width or uneven width. The first circuit layer comprises at least two main circuits greater than 1 meter. an intermediate insulating film having a conductive hole formed thereon, wherein the first circuit layer is exposed from the conductive hole; a second circuit layer, bonded to the intermediate insulating film, wherein the circuits of the second circuit layer are bonded to the first insulating film at some or all of the via holes, and the second circuit layer partially blocks the intermediate insulating film in the via holes; A front solder resist layer is combined on the second circuit layer, and pad windows are provided on the front solder resist layer, wherein some pad windows are provided at the via holes, and each of the pad windows at the via holes exposes both the metal of the first circuit layer and the metal of the second circuit layer; or, among the pad windows at the via holes, some pad windows expose both the metal of the first circuit layer and the metal of the second circuit layer, and some pad windows only expose the metal of the first circuit layer.
[0009] Optionally, the front solder resist layer is an insulating film or solder resist ink.
[0010] Optionally, the thickness of the first circuit layer is greater than or equal to the thickness of the second circuit layer; Optionally, the second circuit layer is a plurality of secondary circuits, or the second circuit layer includes a main circuit and a plurality of secondary circuits.
[0011] Optionally, at the via hole, the first circuit layer and the second circuit layer are both combined on the first insulating film and a pad is formed. The metal of the first circuit layer and the second circuit layer are close to each other, or in contact on the left and right, or the metal part of the second circuit layer overlaps on the first layer circuit.
[0012] Optionally, at the via hole, there is only a pad formed by the metal of the first circuit layer. This pad is used to weld a leg of a component or serve as a shear pad.
[0013] In a third aspect, an embodiment of the present invention provides an LED light strip, comprising the double-layer circuit board described in any one of the embodiments of the second aspect above, wherein electronic components are soldered on the double-layer circuit board, and the soldering pads at some or all of the via holes are soldered with component feet by tin, and the soldering pads at the via holes with the component feet are combined pads formed by a combination of the first circuit layer metal and the second circuit layer metal; or, the soldering pads at the via holes with the component feet are the first circuit layer metal; or, the soldering pads at the via holes are only soldered with tin.
[0014] The second and third aspects of the present invention have at least one of the following beneficial effects: In the embodiments of the present invention, the second circuit layer is combined on the intermediate insulating film, and the circuits of the second circuit layer are combined on the first insulating film at some or all of the via holes. The second circuit layer partially blocks the intermediate insulating film in the via holes, so that when the circuit board is soldered, the intermediate insulating material blocked by the second circuit layer will not repel tin, and the tin can flow smoothly to the two layers of circuit metal, thereby reducing or avoiding the tin void phenomenon and effectively improving the yield of the circuit board. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1.1 It is a schematic diagram of the cross-sectional structure of a traditional circuit board at the location of the via hole; Figure 1.2 yes Figure 1.1 Schematic diagram of the structure after soldering; Figure 1.3 yes Figure 1.2 The schematic diagram of the structure after the structural element feet are welded; Figure 2.1 is a schematic planar structural diagram of the first insulating film in the first embodiment of the present invention; Figure 2.2 is Figure 2.1 A schematic diagram of the planar structure after a first circuit layer is formed on the first insulating film shown; Figure 2.3 1 is a schematic planar structural diagram of an intermediate insulating film with a via hole in a first embodiment of the present invention; Figure 2.4 is Figure 2.3 A schematic diagram of the planar structure after a second circuit layer is formed on the intermediate insulating film shown; Figure 2.5 1 is a schematic planar structural diagram of a second insulating film with a pad window in the first embodiment of the present invention; Figure 2.6 It will Figure 2.2 、 Figure 2.4 and Figure 2.5 A schematic diagram of the planar structure of a circuit board formed after the structures shown are bonded together; Figure 2.7 yes Figure 2.6 Schematic diagram of the cross-sectional structure at the shear pad location (the first and second circuit layers do not overlap at the via hole); Figure 2.8 yes Figure 2.6 Schematic diagram of the cross-sectional structure at the shear pad location (the first and second circuit layers overlap at the via hole); Figure 3.1 is a schematic planar structural diagram of the first insulating film in the second embodiment of the present invention; Figure 3.2 is Figure 3.1 A schematic diagram of the planar structure after a first circuit layer is formed on the first insulating film shown; Figure 3.3 1 is a schematic planar structural diagram of an intermediate insulating film with a via hole in a second embodiment of the present invention; Figure 3.4 is Figure 3.3 A schematic diagram of the planar structure after a second circuit layer is formed on the intermediate insulating film shown; Figure 3.5 The second embodiment of the present invention is made Figure 3.3 Schematic diagram of the structure shown (before etching); Figure 3.6 yes Figure 3.5 A schematic diagram of the cross-sectional structure after the structure shown is combined; Figure 3.7 It will Figure 3.2 、 Figure 3.4 A schematic diagram of the planar structure of a circuit board formed after the structures shown are bonded together; Figure 3.8 yes Figure 3.7 The structure shown is a schematic diagram of the planar structure after the ink solder mask layer is made; Figure 3.9 yes Figure 3.8 Schematic diagram of the cross-sectional structure at the shear pad location (the first and second circuit layers do not overlap at the via hole); Figure 3.10 yes Figure 3.8 Schematic diagram of the cross-sectional structure at the shear pad location (the first and second circuit layers overlap at the via hole); Figure 3.11 yes Figure 3.9 Schematic diagram of the structure after soldering; Figure 3.12 yes Figure 3.10 Schematic diagram of the structure after soldering; Description of Figure Numbers: 10-glue, 1-first insulating film, 2-first circuit layer, 3-intermediate insulating film, 31-conducting hole, 32-protective film, 4-second circuit layer, 41-metal foil, 5-second insulating film, 51-pad window, 6-ink solder mask, 7-scissors pad, 8-pad, 9-tin. DETAILED DESCRIPTION
[0016] To make the purpose, technical solutions and advantages of the present invention more clearly understood, 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 in any manner unless there is any conflict.
[0017] Many different embodiments or examples are provided below for realizing the structure of the present invention.
[0018] See also Figure 2.1-Figure 2.8 As shown, the first embodiment of the present invention provides a method for manufacturing a double-layer circuit board, comprising: See Figure 2.1 , prepare the first insulating film 1 with adhesive 10; see Figure 2.2 As shown, a conductive wire is attached to the first insulating film 1 with adhesive 10 to form a first circuit layer 2; in other embodiments, a metal foil may be attached to the first insulating film 1 with adhesive, and then the unnecessary metal may be removed after die-cutting to form the first circuit layer; See Figure 2.3 As shown, the intermediate insulating film 3 with adhesive on both sides is die-cut to form a conducting hole 31; See Figure 2.4 As shown, a metal foil is attached to the intermediate insulating film 3, and then the metal foil is die-cut and the unnecessary metal is torn off to form the second circuit layer 4; See Figure 2.5 As shown, the second insulating film 5 with glue on the top layer is die-cut to form a pad window 51; See Figure 2.6 As shown, the first insulating film 1 with the first circuit layer 2, the intermediate insulating film 3 with the second circuit layer 4, and the second insulating film 5 with the pad window 51 are aligned and bonded, and then hot-pressed into a circuit board. According to the circuit design, the second circuit layer 4 is bonded to the first insulating film 1 at some or all of the conductive holes 31.
[0019] See Figure 3.1-Figure 3.10 As shown, the second embodiment of the present invention further provides a method for manufacturing a double-layer circuit board, comprising: See Figure 3.1 As shown, a first insulating film 1 with adhesive 10 is prepared; See Figure 3.2 As shown, a conductive wire is attached to the first insulating film 1 with adhesive 10 to form a first circuit layer 2; in other embodiments, a metal foil is attached to the first insulating film 1 with adhesive, and the unnecessary metal is removed after die-cutting to form the first circuit layer; See Figure 3.3 As shown, the intermediate insulating film 3 with adhesive on both sides is die-cut to form a conducting hole 31; See Figure 3.5 and Figure 3.6 As shown, a protective film 32 is attached to one side of the intermediate insulating film 3, and a metal foil 41 is attached to the other side. After hot pressing, the metal foil 41 on the intermediate insulating film 3 is etched using an etching method to obtain a second circuit layer 4, and then the protective film is torn off to obtain Figure 3.4 The structure shown; See Figure 3.7 As shown, the first insulating film 1 with the first circuit layer 2 and the intermediate insulating film 3 with the second circuit layer 4 are aligned and laminated, and then subjected to heat pressing treatment, so that the second circuit layer 4 is bonded to the first insulating film 1 at some or all of the via holes 31; See Figure 3.8 As shown, an ink solder resist layer 6 is formed on the second circuit layer.
[0020] See Figure 2.7 、 Figure 2.8 or Figure 3.9 、 Figure 3.10 As shown, an embodiment of the present invention provides a double-layer circuit board, comprising a first insulating film 1, which is a back solder resist layer; a first circuit layer 2, which is bonded to the first insulating film 1, specifically by bonding with glue 10, and the first circuit layer 2 is a circuit with uniform width (such as Figure 2.2 As shown in FIG, the first circuit layer 2 may also be a circuit with inconsistent widths. The first circuit layer 2 includes at least two main circuits greater than 1 meter. In this embodiment, the first circuit layer 2 includes two main circuits. The intermediate insulating film 3 is provided with a via hole 31. The first circuit layer 2 is exposed from the via hole 31 at the via hole 31. The second circuit layer 4 is bonded to the intermediate insulating film 3. At some or all of the via holes 31, the circuits of the second circuit layer 4 are bonded to the first insulating film 1. The second circuit layer 4 partially blocks the intermediate insulating film 3 in the via hole 31. Figure 2.7 、 Figure 2.8 As shown, the middle insulating film 3 on the right side of the via hole 31 is blocked by the second circuit layer 4; the front solder resist layer is combined on the second circuit layer 4, see Figure 2.7 and Figure 2.8 As shown, the front solder resist layer can be a second insulating film 5, and the second insulating film 5 is bonded to the second circuit layer 4 and the intermediate insulating film 3 by glue 10; Figure 3.9 and Figure 3.10 As shown, the front solder resist layer can also be an ink solder resist layer 6, which is attached to the second circuit layer 4 and the intermediate insulating film 3. The front solder resist layer is provided with pad windows 51, wherein some pad windows 51 are provided at the via holes 31; some pad windows 51 are not provided at the via holes 31, and these pad windows can be used for soldering electronic components; each of the pad windows 51 at the via holes 31 exposes both the metal of the first circuit layer 2 and the metal of the second circuit layer 4, as shown in FIG. Figure 2.6 or, in the pad window 51 at the via hole 31, wherein part of the pad window exposes both the metal of the first circuit layer 2 and the metal of the second circuit layer 4, and part of the pad window exposes only the metal of the first circuit layer 2, such as Figure 2.6 The pad 8 in the middle only exposes the metal of the first circuit layer 2.
[0021] In some embodiments of the present invention, the thickness of the first circuit layer 2 is ≥ the thickness of the second circuit layer 4. The first circuit layer 2 is used as the main line to connect the power supply to ensure sufficient current load; while the second circuit layer 4 is mainly used to connect components (such as LED lamp beads, resistors), and the required current load is smaller. Reducing its thickness is beneficial to cost savings.
[0022] In some embodiments of the present invention, according to circuit design, the second circuit layer 4 is a plurality of secondary circuits; in other embodiments, the second circuit layer 4 includes a main circuit and a plurality of secondary circuits.
[0023] In some embodiments of the present invention, at the via hole 31, the first circuit layer 2 and the second circuit layer 4 are both bonded to the first insulating film 1 and a pad is formed, and the metal of the first circuit layer 2 and the second circuit layer 4 are close to or in contact with each other (e.g. Figure 2.7 or Figure 3.9 In other embodiments, as shown in Figure 2.8 or Figure 3.10 As shown, the metal portion of the second wiring layer 4 overlaps the first wiring layer 2 .
[0024] In some embodiments of the present invention, at the via hole 31 , there is only a pad formed by the metal of the first circuit layer 2 , and this pad is used to weld a leg of a component or serve as a shear pad.
[0025] An embodiment of the present invention also provides an LED light strip, comprising the double-layer circuit board described in any one of the above embodiments, wherein electronic components are soldered on the double-layer circuit board, and the soldering pads at some or all of the via holes 31 are soldered with component feet by tin, and the soldering pads at the via holes to which the component feet are soldered are combined soldering pads formed by a combination of the first circuit layer metal and the second circuit layer metal; or, the soldering pads at the via holes to which the component feet are soldered are the first circuit layer metal; or, the soldering pads at the via holes are only soldered with tin.
[0026] See Figure 3.11-Figure 3.12 As shown, in the embodiment of the present invention, the second circuit layer 4 is combined on the intermediate insulating film 3. At part or all of the conductive holes 31, the circuits of the second circuit layer 4 are combined on the first insulating film 1. The second circuit layer 4 partially blocks the intermediate insulating film 3 in the conductive holes 31. As a result, when the circuit board is soldered, the intermediate insulating material blocked by the second circuit layer 4 does not repel tin. The tin can flow smoothly to the two layers of circuit metal, thereby reducing or avoiding the tin void phenomenon and effectively improving the yield of the circuit board.
[0027] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the relevant technical field without departing from the purpose of the present invention.
Claims
1. A method for manufacturing a double-layer circuit board, characterized in that: include: On the first insulating film with glue, a conductive wire is attached to form a first circuit layer; Alternatively, a metal foil is applied, and after die-cutting, the unnecessary metal is torn off to form a first circuit layer; Die-cut the intermediate insulating film with adhesive on both sides to form a via hole; The metal foil is attached to the intermediate insulating film, and then the metal foil is die-cut and the unnecessary metal is torn off to form the second circuit layer; Die-cut the second insulating film with glue on the top layer to form a pad window; After aligning and laminating the first insulating film with the first circuit layer, the middle insulating film with the second circuit layer, and the second insulating film with the pad window, they are hot pressed into a circuit board, so that the second circuit layer is bonded to the first insulating film at some or all of the via holes.
2. A method for manufacturing a double-layer circuit board, characterized in that: include: On the first insulating film with glue, a conductive wire is attached to form a first circuit layer; Alternatively, a metal foil is applied, and after die-cutting, the unnecessary metal is torn off to form a first circuit layer; Die-cut the intermediate insulating film with adhesive on both sides to form a via hole; A protective film is attached to one side of the intermediate insulating film, and a metal foil is attached to the other side. After hot pressing, the metal foil on the intermediate insulating film is etched using an etching method to obtain a second circuit layer, and then the protective film is torn off; Aligning and laminating the first insulating film with the first circuit layer and the intermediate insulating film with the second circuit layer, and then subjecting them to heat pressing treatment, so that the second circuit layer is bonded to the first insulating film at some or all of the via holes; Make an ink solder mask layer on the second circuit layer.
3. A double-layer circuit board, characterized in that: include: The first insulating film is a back solder resist layer; A first circuit layer, combined on the first insulating film, the first circuit layer is a circuit with uniform width or a circuit with inconsistent width, and the first circuit layer has at least two main circuits greater than 1 meter; An intermediate insulating film is provided with a via hole, wherein the first circuit layer is exposed from the via hole; A second circuit layer is combined on the intermediate insulating film, and the circuits of the second circuit layer are combined on the first insulating film at some or all of the via holes, and the second circuit layer partially blocks the intermediate insulating film in the via holes; A front solder resist layer is combined on the second circuit layer, and pad windows are arranged on the front solder resist layer, wherein some of the pad windows are arranged at the via holes, and each of the pad windows at the via holes exposes both the metal of the first circuit layer and the metal of the second circuit layer; or, the pad windows at the via holes, wherein some of the pad windows expose both the metal of the first circuit layer and the metal of the second circuit layer, and some of the pad windows only expose the metal of the first circuit layer.
4. A double-layer circuit board according to claim 3, characterized in that: The front solder resist layer is an insulating film or solder resist ink.
5. A double-layer circuit board according to claim 3, characterized in that: The thickness of the first circuit layer is greater than or equal to the thickness of the second circuit layer.
6. A double-layer circuit board according to claim 3, characterized in that: The second circuit layer is a plurality of secondary circuits, or the second circuit layer includes a main circuit and a plurality of secondary circuits.
7. A double-layer circuit board according to claim 3, characterized in that: At the via hole, the first circuit layer and the second circuit layer are both combined on the first insulating film and a pad is formed. The metal of the first circuit layer is close to the second circuit layer, or is in contact with each other, or the metal part of the second circuit layer overlaps the first layer circuit.
8. A double-layer circuit board according to claim 3, characterized in that: At the via hole, there is only a pad formed by the metal of the first circuit layer. This pad is used to weld one leg of the component or as a shear pad.
9. An LED light strip, characterized in that: A double-layer circuit board comprising any one of claims 3-8, wherein electronic components are welded on the double-layer circuit board, and component feet are welded to the pads at some or all of the via holes by tinning, and the pads at the via holes welded with the component feet are combined pads formed by combining the first circuit layer metal and the second circuit layer metal; or, the pads at the via holes welded with the component feet are the first circuit layer metal; or, the pads at the via holes are only welded with tin.