Three-terminal fuse and preparation method thereof

Abstract

The invention provides a three-terminal fuse and a preparation method thereof. The fuse comprises BT resin or a PCB substrate and is provided with a through hole. The NiCr alloy conductive circuit is formed through a lift-off photoetching process and emits heat in case of overcurrent; the side electrode is connected with the conductive circuit by adopting a through hole printing process; the silica gel insulating layer prevents short circuit and has conductivity and fusing performance, and the protective layer provides environmental stability. The preparation method comprises the following steps: drilling to form a through hole, printing a side electrode, cleaning and lightly etching a substrate, forming a conductive circuit by adopting a lift-off process, printing an insulating layer, electroplating a melt layer, removing a photoetching film, forming a protective layer and completing packaging. The fuse is simple in structure, accurate in fusing, low in manufacturing cost, suitable for surface mounting, widely applied to the field of consumer electronics and capable of providing reliable overcurrent protection.

Description

Technical Field

[0001] The present invention relates to the technical field of fuses, in particular to a three-terminal fuse and a preparation method thereof. Background Art

[0002] Existing fuses are widely used in electronic circuits to protect circuit components from overcurrent or overheating. However, traditional fuses have limitations in their structural design and manufacturing process, such as imprecise fusing performance of the conductive circuit, high manufacturing costs due to complex photolithography processes, and insufficient stability in the connection between the electrode and the substrate. These issues are particularly prominent in high-precision electronic devices, potentially resulting in poor circuit protection and shortened device lifespan.

[0003] In addition, the insulation and protective layer materials of traditional fuses are easily affected by environmental factors such as moisture or temperature changes during long-term use, which in turn affects the reliability and stability of the device. In order to address the above problems, the industry has tried to improve the performance of fuses by improving substrate materials, optimizing electrode structures, and introducing more advanced manufacturing processes. For example, the use of printed circuit boards or BT resin substrates can improve electrical insulation and mechanical strength, but how to achieve efficient electrode connections and precise formation of conductive lines on these substrates remains a technical difficulty. The existing three-terminal fuse heating element structure is electrically connected to the heating element electrode, and the melt is stacked on the heating element electrode and melted by the heat transferred by the heating element electrode. The preparation process is complicated.

[0004] In addition, the conductivity, oxidation resistance, and solderability of the melt layer of traditional three-terminal fuses are difficult to guarantee during surface mounting and long-term use, requiring a solution with better overall performance. Summary of the Invention

[0005] The present invention aims to provide a three-terminal fuse with a simple structure, low manufacturing cost and stable performance and a preparation method thereof, which has become an urgent problem to be solved in the current technical field.

[0006] To achieve the above objectives, the present invention proposes the following technical solution: a three-terminal fuse, comprising:

[0007] A substrate, the substrate being made of an electrically insulating material and having at least one through hole formed on a side edge of the substrate;

[0008] A heating structure is formed on the surface of the substrate, comprising at least one conductive circuit, wherein the conductive circuit is formed into a thin film containing NiCr components by thin film deposition technology;

[0009] at least one melt layer overlapping and electrically connected to the heating body structure portion;

[0010] At least two side electrodes are formed on both side ends of the substrate, are arranged opposite to each other, and are electrically connected to the melt layer;

[0011] at least one heating body electrode, formed on a side end portion of the substrate, located between opposite side electrodes of the substrate, and electrically connected to the heating body structure;

[0012] an insulating layer, disposed on the surface of the substrate and covering at least a portion of the heating structure;

[0013] The protective layer is arranged on the melt layer.

[0014] Preferably, the melt layer has a narrow portion.

[0015] Preferably, a through structure is provided at a non-end portion of the substrate, and the side electrode covers the through structure.

[0016] Preferably, the insulating layer and / or the protective layer are made of silicone.

[0017] Preferably, the substrate is a BT resin substrate or a printed circuit board.

[0018] Preferably, the surface of the melt is partially provided with a Ni layer and / or a tin layer.

[0019] Preferably, at least one of the heating body structure and the melt layer structure is prepared by a thin film process.

[0020] Preferably, the heating body structure is first formed into a heating body circuit through a yellow light process;

[0021] The second yellowing process is performed before the melt layer is electroplated.

[0022] A method for preparing a three-terminal fuse comprises the following steps:

[0023] Providing a substrate with electrical insulation properties;

[0024] Drilling the substrate to form at least one through-hole, and forming electrodes on both sides of the through-hole using a through-hole printing process, and connecting the electrodes to the conductive circuit;

[0025] The substrate surface is cleaned and lightly etched as needed to passivate the copper edges;

[0026] forming a heating structure on the surface of the substrate;

[0027] A melt layer is formed on the substrate surface, and a portion of the melt layer overlaps the heating body structure;

[0028] printing a protective layer on the melt layer;

[0029] Conduct product electrical testing and finished product packaging.

[0030] Preferably, the through-hole printing uses conductive silver paste or copper paste as the printing material.

[0031] Preferably, the conductive circuit structure of the heating body is formed by using the yellow light process 1;

[0032] A metal film containing NiCr is sputtered on the surface of the substrate, and the film is removed to form a heating body structure;

[0033] Printing an insulating layer on the surface of the conductive circuit;

[0034] The second yellow light process is carried out to form a photoresist pattern in a partial area, and then electroplating forms a melt layer in the partial area, removing the photoresist film, and forming the required melt structure.

[0035] Beneficial effects: The technical solution of this application has the following technical effects:

[0036] The present invention provides a three-terminal fuse and a preparation method thereof. By combining a through-hole design and a lift-off photolithography process on an electrical insulating substrate to form a NiCr alloy conductive circuit and a melt layer structure, the technical problems of traditional fuses in terms of melting accuracy, manufacturing complexity and connection stability are effectively solved. The side electrodes formed by using BT resin or PCB substrate combined with a through-hole printing process not only improve the connection reliability between the electrode and the conductive circuit, but also simplify the manufacturing process and reduce production costs. At the same time, the NiCr alloy conductive circuit is formed by a precise lift-off photolithography process, which ensures a fast melting response under overcurrent conditions, thereby significantly improving the accuracy and safety of circuit protection. It is prepared through a thin film process, replacing the commonly used welding process, reducing the use of solder, and meeting the environmental protection requirements of the product.

[0037] In addition, the insulating layer of the present invention provides excellent electrical isolation and environmental stability, effectively preventing short circuits and resisting erosion by environmental factors such as moisture and temperature changes. Silicone is further selected as a protective layer. When the fuse blows due to abnormal current in the circuit, the silicone protective layer has a certain stretching effect, which can ensure that the fuse blows completely, thereby improving product reliability and segmentation performance. The surface portion of the melt layer is provided with a Ni layer and / or a tin layer, which can lower the melting point, accelerate the product blowing, and make the three-terminal fuse have higher reliability and compatibility. A through structure is provided at the non-end portion of the substrate. The through structure is one or more through holes in a roughly circular shape, which can be filled with a conductor inside to improve the thermal conductivity of the substrate. These characteristics make the three-terminal fuse of the present invention have broad application prospects in high-precision electronic equipment. At the same time, the process optimization of its preparation method further reduces production costs and improves the market competitiveness of the product.

[0038] It should be appreciated that all combinations of the foregoing concepts, as well as additional concepts described in greater detail below, to the extent such concepts are not mutually inconsistent, can be considered to be part of the inventive subject matter of this disclosure.

[0039] The foregoing and other aspects, embodiments, and features of the present invention will be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the present invention, such as features and / or beneficial effects of the exemplary embodiments, will become apparent from the following description or through practice of specific embodiments according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in various figures may be represented by the same reference numeral. For the sake of clarity, not every component is labeled in every figure. Embodiments of various aspects of the present invention will now be described by way of example and with reference to the accompanying drawings, in which:

[0041] Figure 1 It is a schematic top view of the structure of the present invention.

[0042] Figure 2 It is a cross-sectional schematic diagram of the present invention.

[0043] Figure 3 Schematic diagram of the equivalent circuit of the present invention.

[0044] In the figure, the meanings of the various reference numerals are as follows: 1. substrate; 2. heating body structure; 3. melt layer; 4. side electrode; 5. insulating layer; 6. protective layer; 7. through structure; 8. heating body electrode. DETAILED DESCRIPTION

[0045] In order to better understand the technical content of the present invention, specific embodiments are given and described as follows in conjunction with the accompanying drawings. Various aspects of the present invention are described in this disclosure with reference to the accompanying drawings, in which many illustrative embodiments are shown. The embodiments of the present disclosure are not necessarily defined to include all aspects of the present invention. It should be understood that the various concepts and embodiments introduced above, as well as those described in more detail below, can be implemented in any of many ways, because the concepts and embodiments disclosed in the present invention are not limited to any implementation method. In addition, some aspects disclosed in the present invention can be used alone or in any appropriate combination with other aspects disclosed in the present invention.

[0046] Example 1. This embodiment provides a three-terminal fuse, the core structure of which includes a substrate 1, a heater structure 2, side electrodes 4, an insulating layer 5, a melt layer 3, a protective layer 6, and a through-hole structure 7. The substrate 1 is made of BT resin material, which has excellent electrical insulation and mechanical strength. The substrate 1 is provided with through holes for electrode connection. The heater structure 2 is composed of a Ti / NiCr alloy conductive circuit, which is formed on the surface of the substrate 1 using a lift-off photolithography process. Under overcurrent conditions, due to the Joule heating effect, the conductive circuit has heater electrodes at both ends. The electrodes are formed on the side ends of the substrate, located between the opposite side electrodes of the substrate, and are electrically connected to the heater structure. The electrodes 4 on both sides are formed by a through-hole printing process and are electrically connected to the conductive circuit to form a current path. The insulating layer 5 is made of silicone material and covers the conductive circuit to prevent short circuits. The melt layer 3 is composed of copper, nickel, and tin layers formed by electroplating. The copper layer provides conductivity, the nickel layer enhances oxidation resistance, and the tin layer ensures solderability, forming a pad structure suitable for surface mounting. The protective layer 6 is silicone, covers the melt layer 3 and the exposed area, and provides mechanical protection and environmental stability.

[0047] The preparation process first selects a BT resin substrate 1 and forms a through hole by drilling to provide a connection channel for the side electrode 4. The through-hole printing process uses conductive copper paste to fill the through hole and form the side electrode 4 to ensure reliable electrical connection with the conductive circuit. The surface of the substrate 1 is cleaned and lightly etched to improve the adhesion of the subsequent metal film. Using a lift-off yellow light process, through photolithography patterning and sputtering of Ti / NiCr alloy, a precise conductive circuit is formed. Its high resistance property causes it to heat up rapidly when overcurrent occurs. Subsequently, a silicone insulation layer 5 is printed to cover the conductive circuit to achieve electrical isolation. In the second yellow light process, a copper layer, a nickel layer and a tin layer are electroplated on the substrate 1 to form a melt layer 3, the excess photoresist film is removed, and a protective layer 6 is applied to enhance the device's resistance to moisture and temperature changes, thereby completing the structural preparation. This method ensures the stability of the device structure and functional reliability through precise photolithography and printing processes.

[0048] Furthermore, a through-hole structure 7 is provided at a non-end portion of the substrate. This through-hole structure 7 comprises one or more generally circular through-holes, which can be filled with a conductor to improve the substrate's thermal conductivity. These characteristics make the three-terminal fuse of the present invention promising for broad application in high-precision electronic equipment. Furthermore, the optimized manufacturing process further reduces production costs and enhances the product's market competitiveness.

[0049] Example 2: A three-terminal fuse based on a PCB substrate 1. The three-terminal fuse of this embodiment is similar to that of Example 1, except that the substrate 1 uses a printed circuit board PCB, which has electrical insulation and processing compatibility suitable for large-scale production. Through holes are designed on both sides of the substrate 1, and the side electrodes 4 are formed by printing conductive silver paste and are electrically connected to the NiCr alloy conductive circuit. The conductive circuit is formed by a lift-off photolithography process, and its high melting point and resistance characteristics ensure the accuracy of overcurrent protection. The insulating layer 5 is silicone, which covers the conductive circuit to prevent short circuits. The melt layer 3 is composed of three layers of copper, nickel, and tin, which respectively realize the functions of conduction, anti-oxidation, and solderability, and are suitable for surface mounting applications. The protective layer 6 is silicone, which provides environmental isolation and mechanical protection.

[0050] The fabrication process uses a PCB as the substrate 1. Through-holes are formed by drilling to provide connection channels for the side electrodes 4. Through-hole printing uses conductive silver paste to fill the through-holes and form the side electrodes 4, forming an electrical connection with the conductive circuit. The surface of the substrate 1 is cleaned and lightly etched to optimize adhesion in subsequent processes. A lift-off yellow light process is used to form NiCr conductive circuits through photolithography and sputtering. Its patterned design ensures rapid heating in the event of overcurrent. A silicone insulating layer 5 is printed to cover the conductive circuits, providing electrical isolation. The melt layer 3 is sequentially formed into copper, nickel, and tin layers through an electroplating process to ensure conductivity and fusibility. Finally, the photoresist film is removed, and a protective layer 6 is applied to the insulating layer 5 and exposed areas through a yellow light process to enhance environmental stability. This completes the device fabrication. This method leverages the processing advantages of the PCB substrate 1 and the high conductivity of the silver paste to simplify the manufacturing process and improve device reliability.

[0051] The functional principle of the three-terminal fuse is further explained. The substrate 1BT resin or PCB provides electrical insulation and mechanical support, and the through-hole design facilitates the connection between the side electrode 4 and the conductive circuit. The NiCr alloy conductive circuit serves as a heating body. Its high resistance characteristics enable it to generate sufficient Joule heat when overcurrent occurs, which helps to quickly fuse to cut off the circuit and protect downstream components. The side electrode 4 is connected to the conductive circuit through through-hole printing to form a stable current path. The silicone insulation layer 5 isolates the conductive circuit to prevent short circuit or leakage. The protective layer 6 covers the surface of the device to resist environmental factors such as moisture and temperature changes, thereby extending the life of the device. The Cu / Ni / Sn three-layer structure of the melt layer provides low-resistance conduction, anti-oxidation protection and welding compatibility, respectively, to ensure the reliability and stability of the device in surface mounting.

[0052] The preparation method achieves efficient production through a modular process. The through-hole printing process uses a conductive paste to form the side electrode 4 to ensure the stability of the electrical connection. The lift-off photolithography process precisely controls the shape and size of the NiCr conductive line to ensure the consistency of the fusing performance. The printing and curing process of the silicone insulation layer 5 provides electrical isolation and environmental protection, and the process is simple and low-cost. The Cu / Ni / Sn melt layer 3 formed by electroplating optimizes the conductivity and fusing properties through a layered design to meet surface mounting requirements. The entire preparation process combines photolithography, printing and electroplating processes, which not only ensures device performance but also reduces manufacturing complexity and cost.

[0053] While the present invention has been disclosed above with reference to preferred embodiments, this is not intended to limit the present invention. Persons skilled in the art will readily appreciate that various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A three-terminal fuse, characterized in that: include: A substrate, the substrate being made of an electrically insulating material and having at least one through hole formed on a side edge of the substrate; A heating structure is formed on the surface of the substrate, comprising at least one conductive circuit, wherein the conductive circuit is formed into a thin film containing NiCr components by thin film deposition technology; at least one melt layer overlapping and electrically connected to the heating body structure portion; At least two side electrodes are formed on both side ends of the substrate, are arranged opposite to each other, and are electrically connected to the melt layer; at least one heating body electrode, formed on a side end portion of the substrate, located between opposite side electrodes of the substrate, and electrically connected to the heating body structure; an insulating layer, disposed on the surface of the substrate and covering at least a portion of the heating structure; The protective layer is arranged on the melt layer.

2. The three-terminal fuse according to claim 1, characterized in that: The melt layer has a narrow portion.

3. The three-terminal fuse according to claim 1, characterized in that: A through structure is provided at a non-end portion of the substrate, and the side electrode covers the through structure.

4. The three-terminal fuse according to any one of claims 1 to 3, characterized in that: The insulating layer and / or the protective layer are made of silicone.

5. The three-terminal fuse according to claim 1, characterized in that: The substrate is a BT resin substrate or a printed circuit board.

6. The three-terminal fuse according to claim 1, characterized in that: The surface of the melt is partially provided with a Ni layer and / or a tin layer.

7. The three-terminal fuse according to claim 1, characterized in that: At least one of the heating body structure and the melt layer structure is prepared by a thin film process.

8. A method for preparing a three-terminal fuse, characterized in that: The following steps are involved: Providing a substrate with electrical insulation properties; Drilling the substrate to form at least one through-hole, and forming electrodes on both sides of the through-hole using a through-hole printing process, and connecting the electrodes to the conductive circuit; The substrate surface is cleaned and lightly etched as needed to passivate the copper edges; forming a heating structure on the surface of the substrate; A melt layer is formed on the substrate surface, and a portion of the melt layer overlaps the heating body structure; printing a protective layer on the melt layer; Conduct product electrical testing and finished product packaging.

9. The preparation method according to claim 8, characterized in that The through-hole printing adopts conductive silver paste or copper paste as printing material.

10. The preparation method according to claim 8, characterized in that Using yellow light process 1, a conductive circuit structure of the heating body is formed; A metal film containing NiCr is sputtered on the surface of the substrate, and the film is removed to form a heating body structure; Printing an insulating layer on the surface of the conductive circuit; The second yellow light process is carried out to form a photoresist pattern in a partial area, and then electroplating forms a melt layer in the partial area, removing the photoresist film, and forming the required melt structure.

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