Small patch fuse and production process thereof

Abstract

The invention provides a small surface-mounted fuse and a production process thereof, and relates to the technical field of surface-mounted fuses, the small surface-mounted fuse comprises a substrate, a filling groove is formed in the middle of the upper surface of the substrate, a heat insulation layer is fixedly arranged in the filling groove, the upper surfaces of the substrate and the heat insulation layer form a plane in a polishing mode, and the surface of the substrate is provided with a through hole. And a layer of conductive foil is formed on the plane through a vacuum sputtering coating process. According to the small patch fuse, a substrate and a heat insulation layer are mainly used as supporting bodies, a conductive foil is formed through a vacuum sputter coating process, a narrow fusing part is formed through a polishing mode, then polishing and tinning are carried out on the end part of the substrate to form a tinning layer, and the tinning layer is used as an electrode part and forms stable electric connection with the two ends of the conductive foil. The fuse has fewer parts, does not need high-precision assembly equipment and assembly process during assembly, is low in assembly difficulty, and is beneficial to large-scale production.

Description

Technical Field

[0001] This invention relates to the field of surface mount fuse technology, specifically to a small surface mount fuse and its manufacturing process. Background Technology

[0002] Surface mount fuses, also known as surface-mount fuses, are core protection components in electronic circuits and are widely used in electronic devices such as home appliances, smart terminals, automotive electronics, and industrial control. The main function of surface mount fuses is to provide fast melting protection when an overcurrent or short circuit fault occurs in the circuit. As electronic products develop towards miniaturization, high performance, and high integration, the requirements for the size, performance, and consistency of surface mount fuses are also becoming increasingly stringent.

[0003] Surface mount fuses have a small physical structure, and traditional manufacturing processes suffer from problems such as poor process precision control and unstable connections. For example, patent CN120432365U discloses an ultra-miniature surface mount fuse structure and its manufacturing process. This surface mount fuse structure includes a ceramic substrate, two inner electrode components, two end electrode components, and a fuse element. The ceramic substrate serves as the overall support structure. The first and second inner electrodes are respectively inserted into the inner electrode grooves on the sidewalls at both ends of the ceramic substrate to achieve stable embedding and positioning. The two ends of the fuse element are respectively inserted into fuse fixing grooves on the first and second inner electrodes. The end electrode components are respectively connected to the two ends of the ceramic substrate and are conductive to the inner electrode components… As can be seen, it consists of multiple tiny components, and slots and holes need to be made in the ceramic substrate and the inner electrode components. During assembly, due to the extremely small size of the components, high-precision assembly equipment and processes are required, resulting in high assembly difficulty and stringent requirements for error tolerance during the assembly process, making large-scale production difficult. Therefore, we propose a small surface mount fuse and its manufacturing process. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a small patch fuse, including a substrate, a filling groove is formed in the middle of the upper surface of the substrate, a heat insulation layer is fixedly disposed inside the filling groove, the upper surfaces of the substrate and the heat insulation layer are formed into a plane by grinding, and a conductive foil is formed on the plane by vacuum sputtering coating process.

[0005] The substrate is made of a non-conductive material, and its surface, after polishing, has good solderability. The substrate is made of the following materials: 20-25 parts by weight of cycloaliphatic epoxy resin; 8-11 parts by weight of bisphenol A epoxy resin; Copper powder (after oxidation treatment) 60-70 parts by weight; 6-8 parts by weight of methylhexahydrophthalic anhydride curing agent; 30-40 parts by weight of titanium dioxide; 2 parts by weight of maleic anhydride polyamide.

[0006] The cycloaliphatic epoxy resin used is 1,4-cyclohexanediethanol bis(3,4-epoxycyclohexanecarboxylic acid) ester, CAS number 20249-12-1.

[0007] The copper powder has a particle size of 30-50 micrometers and is oxidized in an oxidation furnace at 520℃-600℃ to form a dense oxide layer on the surface of the powder particles. This oxide layer on the surface of the copper powder particles is an insulating layer used to prevent the copper powder particles from conducting electricity with each other, thereby ensuring the insulation capability of the substrate.

[0008] The insulation layer is made of a non-conductive material and is formed by curing and polishing a fluid filler. Its thermal conductivity after curing is less than 0.3 W / m·K. The fluid filler includes: 40-50 parts by weight of silicone-modified epoxy resin (liquid). 60-80 parts by weight of titanium dioxide.

[0009] The two sides of the upper surface of the substrate are polished to remove the conductive foil and form two rows of solder points.

[0010] The upper surface of the heat insulation layer is provided with two abrasion zones. The conductive foil in the abrasion zones is removed by grinding to form a narrower fusion section. Both ends of the substrate are ground and tinned to form a tin layer. The two tin layers are electrically connected to the two ends of the conductive foil, respectively.

[0011] As a further embodiment, a gasket is fixedly disposed on the bottom surface of the substrate, and a transparent protective layer is also disposed on the surface of the conductive foil and the fused portion. This provides the upper surface of the conductive foil and the fused portion with moisture-proof, salt spray-proof, mildew-proof, dust-proof, and insulating effects.

[0012] A manufacturing process for a small surface mount fuse, applicable to the aforementioned small surface mount fuse, includes the following steps: Step 1: Take 20-25 parts by weight of cycloaliphatic epoxy resin, 8-11 parts by weight of bisphenol A epoxy resin, 60-70 parts by weight of copper powder (after oxidation treatment), 6-8 parts by weight of methyl hexahydrophthalic anhydride curing agent, and 30-40 parts by weight of titanium dioxide and mix them evenly to obtain base material A. Then, take 2 parts by weight of maleic acridinium polyamide and dissolve it in 8 parts by weight of acetone, and then mix it evenly with the base material A to obtain base material B. Finally, put base material B into a board mold and cure it at a constant temperature of 205℃ for two hours to obtain a board blank with a thickness of 2-4 mm. Step 2: Based on the dimensions of the finished substrate, set horizontal and vertical dividing lines on the substrate blank, and open filling grooves according to the set spacing; Step 3: Take 40-50 parts by weight of silicone-modified epoxy resin (liquid), 60-80 parts by weight of titanium dioxide, and 30-45 parts by weight of acetone and mix them evenly to prepare a fluid filler. Fill the fluid filler into the filling tank, and then put the board blank into the curing box and cure it at 180°C for two hours to form a heat insulation layer that is fixed to the substrate. Step 4: Next, grind the upper surface of the blank to make the upper surfaces of the substrate and the heat insulation layer form a plane, and then form a conductive foil on the plane by vacuum sputtering coating process. Step 5: Use a machine tool to open "V" shaped grooves along the longitudinal dividing line on the board blank. Use a grinder to grind both sides of the upper surface of each substrate to remove the conductive foil and form two rows of solder points. Then use a grinder to grind the eroded area of ​​each heat insulation layer to remove the conductive foil in the eroded area and form a narrower fusion section. Step 6: Cut the board blank along the transverse dividing line H and the longitudinal dividing line S to divide it into multiple substrates. Then, polish both ends (excluding the top surface) of each substrate to give both ends of each substrate good soldering performance. Then, immerse both ends of the substrate into the molten solder bath of the solder pot to form a soldering layer at both ends of the substrate. The soldering layer covers both ends of the conductive foil and is electrically connected to the conductive foil. Step 7: Spray transparent paint onto the upper surface of the tin plating layer, the heat insulation layer, and the conductive foil.

[0013] Compared with existing technologies, this miniature patch fuse and its manufacturing process have the following advantages: 1. This small surface mount fuse mainly consists of a substrate and a heat insulation layer as a support. A conductive foil is formed through a vacuum sputtering coating process, and a narrow fusing section is formed by grinding. Then, the ends of the substrate are ground and tinned to form a tin layer, which serves as the electrode and forms a stable electrical connection with the two ends of the conductive foil. Therefore, this fuse has fewer components and does not require high-precision assembly equipment and processes during assembly. The assembly difficulty is low, which is conducive to large-scale production.

[0014] 2. This small patch fuse has a heat insulation layer and two abrasion zones on the upper surface of the heat insulation layer. The conductive foil in the abrasion zone is removed by grinding to form a narrower fusion section. Because the heat insulation layer has a low thermal conductivity, the heat conduction rate between the fusion section and the substrate can be reduced, which allows the fusion section to heat up quickly and melt quickly when the current is large.

[0015] Third, the substrate produced by the manufacturing process of this small surface mount fuse has good solderability after polishing. The two ends of the substrate can be immersed in the molten solder bath of the solder pot to form a solder layer (electrode part) at the two ends of the substrate, which can further simplify its assembly process.

[0016] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0017] Figure 1 This is a structural diagram showing the substrate and insulation layer in a small patch fuse. Figure 2 This is a structural diagram of the substrate, heat insulation layer, and conductive foil in a small surface mount fuse. Figure 3 This is a schematic diagram of the structure of the substrate and the upper surface of the heat insulation layer in a small patch fuse. Figure 4 Finished structure of small surface mount fuses Figure 1 (Top-down view); Figure 5 Finished structure of small surface mount fuses Figure 2 (Looking up from below) Figure 6 This is a reference diagram for steps one and two in the fuse manufacturing process; Figure 7 This is a reference diagram for step three in the fuse manufacturing process; Figure 8 This is a reference diagram for steps four and five in the fuse manufacturing process; Figure 9 This is a reference diagram for step five in the fuse manufacturing process.

[0018] In the picture: 1. Substrate; 101. Filler groove; 102. Soldering point; 103. Soldering layer; 104. Spacer; 2. Insulation layer; 201. Abrasion zone; 3. Conductive foil; 301. Fuse. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] Please see Figures 1-9The present invention provides the following embodiment: a small patch fuse, comprising a substrate 1, wherein a filling groove 101 is formed in the middle of the upper surface of the substrate 1, and a heat insulation layer 2 is fixedly disposed inside the filling groove 101. The upper surfaces of the substrate 1 and the heat insulation layer 2 are formed into a plane by grinding, and a conductive foil 3 is formed on the plane by vacuum sputtering deposition. The conductive foil 3 can be copper foil or lead foil, and the thickness of the conductive foil 3 is set according to the operating current of the fuse, generally 50μm to 100μm.

[0021] The substrate 1 is made of a non-conductive material, and its surface has good tinning performance after polishing. The substrate 1 is made of the following materials: 20-25 parts by weight of cycloaliphatic epoxy resin, 8-11 parts by weight of bisphenol A epoxy resin, 60-70 parts by weight of copper powder (after oxidation treatment), 6-8 parts by weight of methyl hexahydrophthalic anhydride curing agent, 30-40 parts by weight of titanium dioxide, and 2 parts by weight of maleic anhydride polyamide.

[0022] The cycloaliphatic epoxy resin used is 1,4-cyclohexanediethanol bis(3,4-epoxycyclohexanecarboxylic acid) ester, CAS number 20249-12-1.

[0023] The copper powder has a particle size of 30-50 micrometers and is oxidized at 520℃-600℃ in an oxidation furnace to form a dense oxide layer on the surface of the powder particles. The oxide layer on the surface of the copper powder particles is an insulating layer used to prevent the copper powder particles in the copper powder from conducting electricity with each other, thereby ensuring the insulation capability of the substrate 1.

[0024] The heat insulation layer 2 is made of a non-conductive material. The heat insulation layer 2 is formed by curing and polishing a fluid filler, and its thermal conductivity after curing is less than 0.3 W / m·K.

[0025] Specifically, the fluid packing includes: 40-50 parts by weight of silicone-modified epoxy resin (liquid). 60-80 parts by weight of titanium dioxide.

[0026] Please refer to this carefully. Figure 3 and Figure 4 The two sides of the upper surface of the substrate 1 are polished to remove the conductive foil 3 and form two rows of solder points 102.

[0027] The upper surface of the heat insulation layer 2 is provided with two abrasion areas 201. The conductive foil 3 of the abrasion area 201 is removed by grinding to form a narrower fusible part 301. The width of the fusible part 301 is set according to the working current of the fuse.

[0028] Both ends of the substrate 1 are polished and tinned to form tin-coated layers 103, and the two tin-coated layers 103 are electrically connected to both ends of the conductive foil 3. In use, the tin-coated layers 103 serve as electrodes and are soldered onto the circuit board, connecting the fuse in series in the circuit. When the current exceeds a set current, the temperature at the fusing part 301 rises rapidly, causing it to melt and thus protecting the circuit. Because the heat insulation layer 2 has a low thermal conductivity, it reduces the heat transfer rate between the fusing part 301 and the substrate 1, allowing the fusing part 301 to heat up rapidly and melt quickly when the current is high.

[0029] Please refer to this carefully. Figure 3 and Figure 4 In the above-described scheme, the tinning layer 103 covers the upper surfaces of both ends of the conductive foil 3, and the tinning layer 103 and the covering portion of the conductive foil 3 are provided with tinning points 102, which can improve the adhesion between the tinning layer 103 and the substrate 1. That is, the two ends of the conductive foil 3 are sandwiched between the tinning layer 103 and the substrate 1, which can also improve the structural force between the conductive foil 3 and the substrate 1, thereby improving the structural stability of the fuse and ensuring the electrical connection between the tinning layer 103 and the conductive foil 3.

[0030] As a further embodiment, a gasket 104 is fixedly disposed on the bottom surface of the substrate 1, and a transparent protective layer is also disposed on the surface of the conductive foil 3 and the fuse part 301. This gives the upper surface of the conductive foil 3 and the fuse part 301 the effects of moisture-proof, salt spray-proof, mildew-proof, dust-proof, and insulation.

[0031] A manufacturing process for a small surface mount fuse, applicable to the aforementioned small surface mount fuse, includes the following steps: Step 1: Take 20-25 parts by weight of cycloaliphatic epoxy resin, 8-11 parts by weight of bisphenol A epoxy resin, 60-70 parts by weight of copper powder after oxidation treatment, 6-8 parts by weight of methyl hexahydrophthalic anhydride curing agent, and 30-40 parts by weight of titanium dioxide and mix them evenly to obtain base material A. Then, take 2 parts by weight of maleic acridinium polyamide and dissolve it in 8 parts by weight of acetone, and mix it evenly with the base material A to obtain base material B. Finally, put base material B into a board mold and cure it at a constant temperature of 205℃ for two hours to obtain a board blank with a thickness of 2-4 mm.

[0032] Step 2: Based on the dimensions of the finished substrate 1, set the transverse dividing line H and the longitudinal dividing line S on the substrate blank, and open the filling groove 101 according to the set spacing.

[0033] like Figure 6As shown, in steps one and two, the blank obtained in step one can be cut into multiple substrates 1, and after the surface of the blank is polished, the surface of the copper powder particles will be exposed, thereby achieving good tinning performance. In step two, a filling groove 101 is set on the substrate 1 as the base pit of the heat insulation layer 2.

[0034] Step 3: Take 40-50 parts by weight of silicone-modified epoxy resin (liquid), 60-80 parts by weight of titanium dioxide, and 30-45 parts by weight of acetone, mix them evenly to prepare a fluid filler. Fill the fluid filler into the filling tank 101, then place the board blank into the curing chamber and cure it at 180°C for two hours to form a heat insulation layer 2 that is fixed integrally with the substrate 1. Figure 7 As shown.

[0035] Step 4: Next, grind the upper surface of the substrate blank to make the upper surfaces of the substrate 1 and the heat insulation layer 2 form a plane. Then, form a conductive foil 3 on the plane using a vacuum sputtering deposition process, such as... Figure 8 As shown.

[0036] Step 5: Using a machine tool, create "V" shaped grooves along the longitudinal dividing line S on the board blank. Then, use a grinder to grind both sides of the upper surface of each substrate 1 to remove the conductive foil 3, forming two rows of solder joints 102. Next, use a grinder to grind the etched areas 201 of each heat insulation layer 2, removing the conductive foil 3 from the etched areas 201 to form narrower fusion breaks 301. Figure 8 and Figure 9 As shown.

[0037] Step Six: Cut the board blank along the transverse dividing line H and the longitudinal dividing line S to divide it into multiple substrates 1. Then, polish both ends (excluding the top surface) of each substrate 1 to ensure good solderability at both ends. Then, immerse both ends of the substrate 1 into the molten solder bath of the solder pot to form a solder layer 103 at both ends of the substrate 1. The solder layer 103 covers both ends of the conductive foil 3 and is electrically connected to the conductive foil 3. Figure 3 , Figure 4 and Figure 5 As shown.

[0038] Step 7: Spray transparent varnish onto the upper surfaces of the tin-coated layer 103, the heat insulation layer 2, and the conductive foil 3. The transparent varnish serves as a transparent protective layer for the conductive foil 3 and the surface of the fused section 301.

[0039] In summary, the present invention proposes a small surface mount fuse, which mainly consists of a substrate 1 and a heat insulation layer 2 as supports. A conductive foil 3 is formed by vacuum sputtering, and a narrow fusing portion 301 is formed by polishing. Then, the ends of the substrate 1 are polished and tinned to form a tin layer 103, which serves as the electrode portion and forms a stable electrical connection with both ends of the conductive foil 3. As can be seen, this fuse has fewer components, and high-precision assembly equipment and processes are not required during assembly, making assembly easier and conducive to large-scale production. In addition, the substrate 1 produced by this small surface mount fuse manufacturing process has good tinning performance after polishing. The tin layer 103 (electrode portion) can be formed at both ends of the substrate 1 simply by immersing both ends of the substrate 1 in the molten solder bath of the solder pot, which further simplifies the assembly process and facilitates assembly.

[0040] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A small patch fuse, comprising a substrate (1), characterized in that: A filling groove (101) is provided in the middle of the upper surface of the substrate (1). A heat insulation layer (2) is fixedly provided inside the filling groove (101). The upper surfaces of the substrate (1) and the heat insulation layer (2) are formed into a plane by grinding. A conductive foil (3) is formed on the plane by vacuum sputtering coating process. The substrate (1) is made of a non-conductive material, and its surface has good solderability after polishing. The substrate (1) is made of the following materials: 20-25 parts by weight of cycloaliphatic epoxy resin; 8-11 parts by weight of bisphenol A epoxy resin; Copper powder (after oxidation treatment) 60-70 parts by weight; 6-8 parts by weight of methylhexahydrophthalic anhydride curing agent; 30-40 parts by weight of titanium dioxide; 2 parts by weight of maleic pine anhydride polyamide; The heat insulation layer (2) is made of a non-conductive material. The heat insulation layer (2) is formed by curing and polishing a fluid filler. Its thermal conductivity after curing is less than 0.3 W / m·K. The fluid filler includes: 40-50 parts by weight of silicone-modified epoxy resin (liquid). 60-80 parts by weight of titanium dioxide; The two sides of the upper surface of the substrate (1) are polished to remove the conductive foil (3) and form two rows of solder points (102). The upper surface of the heat insulation layer (2) is provided with two abrasion areas (201). The conductive foil (3) in the abrasion area (201) is removed by grinding to form a narrower fusion section (301). Both ends of the substrate (1) are ground and tinned to form a tinned layer (103). The two tinned layers (103) are electrically connected to the two ends of the conductive foil (3) respectively.

2. The miniature patch fuse according to claim 1, characterized in that: A gasket (104) is fixedly provided on the bottom surface of the substrate (1), and a transparent protective layer is also provided on the surface of the conductive foil (3) and the fuse part (301).

3. A manufacturing process for a small surface mount fuse, applicable to the small surface mount fuse described in claim 1, characterized in that: Includes the following steps: Step 1: Take 20-25 parts by weight of cycloaliphatic epoxy resin, 8-11 parts by weight of bisphenol A epoxy resin, 60-70 parts by weight of copper powder (after oxidation treatment), 6-8 parts by weight of methyl hexahydrophthalic anhydride curing agent, and 30-40 parts by weight of titanium dioxide and mix them evenly to obtain base material A. Then, take 2 parts by weight of maleic acridinium polyamide and dissolve it in 8 parts by weight of acetone, and then mix it evenly with the base material A to obtain base material B. Finally, put base material B into a board mold and cure it at a constant temperature of 205℃ for two hours to obtain a board blank with a thickness of 2-4 mm. Step 2: Based on the dimensions of the finished substrate (1), set horizontal and vertical dividing lines on the substrate blank, and open filling grooves (101) according to the set spacing. Step 3: Take 40-50 parts by weight of silicone-modified epoxy resin (liquid), 60-80 parts by weight of titanium dioxide, and 30-45 parts by weight of acetone and mix them evenly to prepare a fluid filler. Fill the fluid filler into the filling tank (101), and then put the board blank into the curing box and cure it at 180°C for two hours to form a heat insulation layer (2) that is fixed to the substrate (1). Step 4: Polish the upper surface of the blank to make the upper surfaces of the substrate (1) and the heat insulation layer (2) form a plane, and then form a conductive foil (3) on the plane by vacuum sputtering coating process. Step 5: Using a machine tool, a "V" shaped groove is opened on the plate blank along the longitudinal dividing line S. A grinding machine is used to grind both sides of the upper surface of each substrate (1) to remove the conductive foil (3) and form two rows of solder points (102). Then, the grinding machine is used to grind the etched area (201) of each heat insulation layer (2) to remove the conductive foil (3) in the etched area (201) and form a narrower fused part (301). Step 6: Cut the board blank along the transverse dividing line H and the longitudinal dividing line S to divide it into multiple substrates (1). Then polish the two ends (excluding the upper surface) of each substrate (1) so that the two ends of each substrate (1) have good soldering performance. Then immerse the two ends of the substrate (1) into the molten solder bath of the solder furnace so that the two ends of the substrate (1) form a soldering layer (103) and the soldering layer (103) covers the two ends of the conductive foil (3) and is electrically connected to the conductive foil (3). Step 7: Spray transparent paint onto the upper surfaces of the tin plating layer (103), the heat insulation layer (2), and the conductive foil (3).

4. The manufacturing process of a small patch fuse according to claim 3, characterized in that: The copper powder has a particle size of 30-50 micrometers and is oxidized in an oxidation furnace at 520℃-600℃ to form a dense oxide layer on the surface of the powder particles.

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