Three-terminal safety structure

Abstract

The utility model provides a three-terminal safety structure, a heating body is arranged at the bottom of a support body, an insulating layer is arranged between the heating body and a safety circuit, and an inflow terminal, an outflow terminal and a control terminal are arranged at the bottom of the insulating layer; the inflow terminal, the outflow terminal and the control terminal are connected through a safety circuit; in an overcurrent state, the safety circuit is fused; the control terminal is connected with the outflow terminal through the heating body to form a control circuit, the heating body emits heat in an overvoltage state, and heat penetrates through the insulating layer to fuse the safety circuit. When the circuit is over-current or over-voltage and the safety circuit is fused, as the safety circuit is arranged on one side of the inflow terminal, the outflow terminal and the control terminal, which are connected to the circuit, sparks generated during fusing cannot be diffused or sputtered to other devices, so that the other devices can be prevented from being damaged or fires, and the safety performance is improved; and a cover does not need to be arranged, so that the occupied space can be reduced, the overall structure is more compact, and meanwhile, the cost is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of circuit protection elements, in particular to a three-terminal fuse structure. Background Art

[0002] A three-terminal fuse typically consists of three terminals, two of which are used to connect to the circuit, and one terminal is connected to an internal resistance heating element. A fusible metal is provided inside to melt in the event of an overcurrent or short circuit, while the resistance heating element is used to cut off the circuit by heating the fuse circuit in the event of an overvoltage.

[0003] In the existing technology, a three-terminal fuse structure is usually provided with a cover covering the fuse circuit to prevent sparks from spreading and sputtering when the fuse circuit blows in the event of overcurrent, causing damage to other devices or fire. However, the provision of the cover increases the overall structure space occupied by the three-terminal fuse structure and increases processing costs.

[0004] In existing technologies, the carrier substrate of a three-terminal fuse is typically a ceramic substrate, on which both the electrodes and the fuse metal are disposed. This presents at least the following technical issues: Due to the characteristics of the ceramic substrate, the overall thickness of the three-terminal fuse is increased; and the manufacturing process involves numerous steps, resulting in low production efficiency and high costs. Utility Model Content

[0005] The main purpose of the utility model is to provide a three-terminal fuse structure with a simple and compact overall structure, high production capacity and low cost. When the fuse is blown, it can prevent sparks from spreading and splashing to damage other components and prevent fire, thereby improving safety performance.

[0006] To achieve the above-mentioned purpose, the present invention provides a three-terminal fuse structure, comprising a support body, a heating element and a fuse circuit;

[0007] The heating element is arranged at the bottom of the support body, an insulating layer is arranged between the heating element and the safety circuit, and an inlet terminal, an outlet terminal, and a control terminal are arranged at the bottom of the insulating layer;

[0008] The inflow terminal, the outflow terminal, and the control terminal are connected via the safety circuit;

[0009] In the overcurrent state, the fuse circuit is blown;

[0010] The control terminal is connected to the outflow terminal through a heating element to form a control circuit.

[0011] In this state, the heating element generates heat, and the heat passes through the insulating layer to melt the fuse circuit.

[0012] Optionally, in one embodiment, an inlet pad and an outlet pad are respectively provided at the bottom of both sides of the insulating layer, and the safety circuit is provided between the inlet terminal and the outflow terminal, and the safety circuit is electrically connected to the inlet terminal and the outflow terminal through the inlet pad and the outflow pad.

[0013] Optionally, in one embodiment, a control pad is provided at the bottom of the insulating layer, the control terminal is electrically connected to the control pad through the heating element, and the control pad is electrically connected to the inflow terminal through the safety circuit.

[0014] Optionally, in one embodiment, both ends of the heating element are connected to heating end pads, the insulating layer is provided with a conductive hole that is conductive to the heating end pad, one end of the heating element is electrically connected to the control terminal through the conductive hole, and the other end of the heating element is electrically connected to the control pad through the conductive hole.

[0015] Optionally, in one embodiment, the longitudinal projection of the heating element falls within the longitudinal projection of the safety circuit.

[0016] Optionally, in one embodiment, a solder resist layer is further included, wherein the solder resist layer is arranged at the bottom of the fuse circuit, and the solder resist layer completely covers the fuse circuit.

[0017] Optionally, in one embodiment, a protective layer is provided on the top of the support body, and the protective layer is used to protect the support body.

[0018] Optionally, in one embodiment, the material of the support body includes at least one of glass fiber, epoxy resin, phenolic resin, polytetrafluoroethylene material, and BT resin material.

[0019] Optionally, in one embodiment, the material of the insulating layer is the same as that of the supporting body.

[0020] Optionally, in one embodiment, the safety circuit is an alloy of one or any combination of tin, lead, copper, silver, zinc, and aluminum.

[0021] In the overall structure of the three-terminal fuse structure of the present invention, an inlet terminal, an outlet terminal and a control terminal are provided at the bottom of the insulating layer, and the inlet terminal, the outlet terminal and the control terminal are connected through the fuse circuit; when the circuit is overcurrent or overvoltage, the fuse circuit blows, and since the fuse circuit is provided on the side where the inlet terminal, the outlet terminal and the control terminal are connected to the circuit, the inlet terminal, the outlet terminal and the control terminal are electrically connected to the external device or component, and the fuse circuit is located between the external device and the support body, the sparks generated by the fuse circuit when it blows are isolated by the support body and will not scatter or splash to other devices, thereby avoiding damage to other devices or fire, thereby improving safety performance; and such a structure does not require a cover, thereby reducing the occupied space, making the overall structure more compact, and also reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] One or more embodiments are exemplarily described by corresponding drawings, which do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0023] Figure 1 This is a schematic cross-sectional view of an embodiment of the present invention;

[0024] Figure 2 A schematic cross-sectional view of another embodiment of the present invention;

[0025] Figure 3 An exploded view of an embodiment of the present invention;

[0026] Figure 4 This is a schematic diagram of the cross-sectional structure of a support body according to an embodiment of the present invention;

[0027] Figure 5 This is a schematic cross-sectional view of a support body according to an embodiment of the present invention, in which an insulating layer and a heating element are added;

[0028] Figure 6 This is a schematic diagram of the cross-sectional structure of the insulating layer after laser drilling in one embodiment of the present utility model;

[0029] Figure 7 This is a schematic diagram of the cross-sectional structure of an electroplated fuse circuit and a solder mask layer added in one embodiment of the present invention;

[0030] Figure 8 This is a schematic diagram of the cross-sectional structure of an embodiment of the present invention with a protective layer added.

[0031] Reference numerals: support body 10 , insulating layer 11 , conductive hole 111 , protection circuit 12 , heating element 13 , heating end pad 131 , inflow terminal 14 , outflow terminal 15 , control terminal 16 , inflow pad 17 , outflow pad 18 , control pad 19 , solder resist layer 20 , protection layer 21 . DETAILED DESCRIPTION

[0032] In order to facilitate the understanding of the present invention, the present invention will be described in more detail below with reference to the accompanying drawings and specific embodiments. It should be noted that when an element is described as being "fixed to" another element, it may be directly on the other element, or one or more elements may be present in between. When an element is described as being "connected to" another element, it may be directly connected to the other element, or one or more elements may be present in between. The terms "vertical", "horizontal", "left", "right", "inside", "outside" and similar expressions used in this specification are for illustrative purposes only. In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating relative importance or implicitly indicating the number of technical features indicated. Therefore, unless otherwise stated, features defined as "first" and "second" may be explicitly or implicitly

[0033] The term "include" and any variation thereof are intended to be non-exclusive and include one or more of the features; "plurality" means two or more. The term "include" and any variation thereof are intended to be non-exclusive and include one or more other features, integers, steps, operations, units, components and / or combinations thereof.

[0034] Furthermore, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be interpreted broadly. For example, they can refer to fixed, removable, or integral connections; mechanical or electrical connections; direct connections, indirect connections through an intermediary, or internal communication between two components. All technical and scientific terms used in this specification have the same meanings as commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification are intended solely for the purpose of describing specific embodiments and are not intended to limit this invention. The term "and / or" as used in this specification includes any and all combinations of one or more of the relevant listed items.

[0035] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0036] Please refer to Figure 1. The present invention provides a three-terminal fuse structure, including a support body 10, a heating element 13 and a fuse circuit 12; the heating element 13 is arranged at the bottom of the support body 10, and an insulating layer 11 is provided between the heating element 13 and the fuse circuit 12. The bottom of the insulating layer 11 is provided with an inlet terminal 14, an outlet terminal 15, and a control terminal 16; the inlet terminal 14, the outlet terminal 15, and the control terminal 16 are connected through the fuse circuit 12; in an overcurrent state, the fuse circuit 12 is blown; the control terminal 16 is connected to the outlet terminal 15 through the heating element 13 to form a control circuit. In an overvoltage state, the heating element 13 generates heat, and the heat passes through the insulating layer 11 to blow the fuse circuit 12.

[0037] In the overall structure of the three-terminal fuse structure, an inlet terminal 14, an outlet terminal 15, and a control terminal 16 are provided at the bottom of the insulating layer 11, and the inlet terminal 14, the outlet terminal 15, and the control terminal 16 are connected through the fuse circuit 12; when the circuit is overcurrent or overvoltage, the fuse circuit 12 blows. Since the fuse circuit 12 is provided on the side where the inlet terminal 14, the outlet terminal 15, and the control terminal 16 are connected to the circuit, the sparks generated when the fuse blows will not scatter or splash to other devices, thereby preventing damage to other devices or fire, thereby improving safety performance; and such a structure does not require a cover, thereby reducing the occupied space, making the overall structure more compact, and also reducing costs.

[0038] Specifically, in one embodiment of the present invention, an inlet pad 17 and an outlet pad 18 are respectively provided at the bottom of both sides of the insulating layer 11, and the safety circuit 12 is provided between the inlet terminal 14 and the outlet terminal 15. The safety circuit 12 is electrically connected to the inlet terminal 14 and the outlet terminal 15 through the inlet pad 17 and the outlet pad 18.

[0039] connect.

[0040] The fuse circuit 12 is electrically connected to the inlet terminal 14 and the outlet terminal 15 through the inlet pad 17 and the outlet pad 18, respectively. The inlet terminal 14 and the outlet terminal 15 are connected in series with the external overcurrent protection circuit. When an overcurrent occurs, the current in the fuse circuit 12 increases sharply. Heat accumulates rapidly as the current continues to increase, causing the temperature to rise. When the temperature exceeds the melting point, the fuse circuit 12 melts, the circuit is disconnected, and overcurrent protection is achieved.

[0041] 2 and 3 , a control pad 19 is provided at the bottom of the insulating layer 11 , the control terminal 16 is electrically connected to the control pad 19 through the heating element 13 , and the control pad 19 is electrically connected to the inflow terminal 14 through the insurance circuit 12 .

[0042] The control terminal 16 is electrically connected to the control pad 19 through the heating element 13. The inflow terminal 14 and the control terminal 16 are connected in series with the external overvoltage protection circuit. The external overcurrent protection circuit and the overvoltage protection circuit are connected in parallel. A MOSFET is provided on the overvoltage protection circuit. When the voltage on the overvoltage protection circuit reaches the protection threshold, the MOSFET will change the overvoltage protection circuit from an open circuit to a pass circuit, allowing current to flow through the heating element 13. The heating element 13 generates heat and generates heat. The heat is transferred to the fuse circuit 12 through the insulating layer 11. The fuse circuit 12 heats up rapidly and melts when the temperature reaches the melting point, and the overvoltage protection circuit is disconnected.

[0043] Furthermore, both ends of the heating element 13 are connected to a heating end pad 131, and the insulating layer 11 is provided with a conductive hole 111 that is conductive with the heating end pad 131. One end of the heating element 13 is electrically connected to the control terminal 16 through the conductive hole 111, and the other end of the heating element 13 is electrically connected to the control pad 19 through the conductive hole 111.

[0044] The insulating layer 11 is provided with a conductive hole 111, which enables the control terminal 16 to be connected to the heating element 13 through the conductive hole 111 and the heating end pad 131, ensuring that current flows to the heating element 13 through the control terminal 16, thereby making the heating element 13 heat stably and reliably when overvoltage occurs.

[0045] In one embodiment of the present invention, the longitudinal projection of the heating element 13 falls within the longitudinal projection of the safety circuit 12 .

[0046] The longitudinal projection of the heating element 13 falls within the longitudinal projection of the fuse circuit 12 , which ensures that the heat generated by the heating element 13 can be effectively transferred to the fuse circuit 12 , causing the fuse circuit 12 to fuse.

[0047] In one embodiment of the present invention, a solder resist layer 20 is further included. The solder resist layer 20 is disposed at the bottom of the fuse circuit 12 and completely covers the fuse circuit 12 .

[0048] The solder resist layer 20 covers the fuse circuit 12 and protects the fuse circuit 12 from environmental factors, thereby preventing the fuse circuit 12 from corrosion and oxidation, and extending the service life and stability of the fuse circuit 12.

[0049] Furthermore, the solder resist layer 20 is made of solder resist ink, which can form an insulating film on the fuse circuit 12 to effectively prevent the solder from flowing into the fuse circuit 12 during soldering and causing a short circuit problem.

[0050] In an embodiment of the present invention, a protective layer 21 is provided on the top of the support body 10 , and the protective layer 21 is used to protect the support body 10 .

[0051] The protective layer 21 can protect the support body 10 from erosion by the external environment, such as oxidation and corrosion, to a certain extent, thereby protecting the support body 10 and extending the service life of the support body 10.

[0052] In an embodiment of the present invention, the support body 10 is made of one or more of glass fiber material, epoxy resin material, phenolic resin material, polytetrafluoroethylene material, and BT resin material.

[0053] The support 10 may be a common resin substrate or organic substrate that can be produced in a large area and is made of glass fiber material, epoxy resin material, phenolic resin material, polytetrafluoroethylene material, BT resin material, etc.

[0054] Specifically, in this embodiment, the support body 10 can be made of FR-4 composite material. FR-4 composite material is made of a quadrifunctional epoxy resin plus a filler and glass fiber. FR-4 material has good mechanical strength, electrical insulation and high temperature resistance, and is easy to process and cut, making it suitable for large-scale production.

[0055] It should be noted that the support 10 can also be a CEM-1 or CEM-2 substrate, which is a paper-based or composite substrate, usually made of cellulose paper impregnated with phenolic resin or epoxy resin; a polyimide PI substrate can be selected, which has excellent heat resistance, electrical insulation and mechanical properties and is often used in high-performance or high-reliability electronic applications.

[0056] Preferably, the material of the insulating layer 11 is the same as that of the support body 10, and thus, the insulating layer 11 and the support body 10 have the same properties;

[0057] The support body 10 and the insulating layer 11 use common printed circuit board substrate materials, as well as printed circuit board drilling, embedded resistors and capacitors, lamination and other process technologies. Compared with the use of ceramic materials and ceramic processes in the existing technology, the use of printed circuit board substrate materials can be directly laminated over a large area during production, thereby improving production efficiency and reducing costs.

[0058] Preferably, the safety circuit 12 is an alloy of one or any combination of tin, lead, copper, silver, zinc, and aluminum.

[0059] The safety circuit 12 forms a weak electrical connection with the external circuit. The weak electrical connection allows the external circuit to pass through the safety circuit 12 during normal operation without causing the safety circuit 12 to fuse.

[0060] Specifically, the safety circuit 12 is a thin metal layer added on the inlet pad 17, the outlet pad 18, and the control pad 19 by chemical deposition, evaporation, sputtering, or electroplating. The thin metal layer is made of one of tin, lead, copper, silver, zinc, aluminum, or a composite alloy material.

[0061] In the embodiment of the present invention, the safety circuit 12 is preferably a thin metal layer made by electroplating tin; since tin has good electrical conductivity, the safety circuit 12 has good electrical conductivity.

[0062] 3 to 8 , the specific implementation steps of an embodiment of the present invention are as follows:

[0063] Step 1: blanking; wherein, a common PCB substrate other than a ceramic substrate and a metal substrate is used as the support 10, and the support 10 is preferably an organic substrate and a resin substrate;

[0064] Step 2: First pattern production: Pattern production is performed on the upper surface of the support 10 to add the heating element 13 and heating end pads 131 added at both ends of the heating element;

[0065] Step 3: First Lamination; Laminating the insulating layer 11 and the copper foil on the upper surface of the support 10 and the heating element 13. The copper foil forms three pads and a connecting terminal. The three pads are the inflow pad 17, the outflow pad 18 and the control pad 19. The connecting terminal is the control terminal 16.

[0066] Step 4: Drilling; Conductive holes 111 are drilled in the insulating layer 11 at positions corresponding to the heating end pads 131 at both ends of the heating element 13. The control terminal 16 is connected to the heating end pad 131 at one end of the heating element 13 through the conductive hole 111, and the control pad 19 is connected to the heating end pad 131 at the other end of the heating element 13 through the conductive hole 111;

[0067] Step 5: First copper deposition and electroplating to make the conductive hole 111 conductive;

[0068] Step 6: Second pattern making: Making the circuits on the upper and lower surfaces of the three-terminal fuse structure;

[0069] Step 7: Fuse fabrication: A thin metal layer of tin, lead, copper, silver, zinc, aluminum, or a composite alloy thereof is added to the three pads by chemical deposition, evaporation, sputtering, or electroplating to form a fuse circuit 12. The fuse circuit 12 is electrically connected to the three pads.

[0070] Step 8: Solder mask fabrication: A layer of solder mask material is evenly coated on the surface of the fuse circuit 12 to obtain a solder mask layer 20;

[0071] Step 9: Second electroplating: Perform electroplating thickening treatment on the control terminal 16, and electroplating on the inlet pad 17 and the outlet pad 18 to form the inlet terminal 14 and the outlet terminal 15;

[0072] Step 10: Surface coating: Coating a solder resist material on the lower surface of the support 10 as a protective layer 21;

[0073] Step 11: Cutting single grains; cutting the entire large substrate into the size of a single product to complete the production of the three-terminal insurance structure.

[0074] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Under the concept of the present invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the above aspects of the present invention. For the sake of simplicity, they are not provided in detail. Although the present invention is described with reference to the above embodiments,

[0075] The utility model has been described in detail, and ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the various embodiments of the utility model.

Claims

1. A three-terminal fuse structure, characterized in that: include: A supporting body (10), a heating element (13) and a safety circuit (12); The heating element (13) is arranged at the bottom of the support body (10), an insulating layer (11) is provided between the heating element (13) and the safety circuit (12), and an inlet terminal (14), an outlet terminal (15), and a control terminal (16) are provided at the bottom of the insulating layer (11); The inflow terminal (14), the outflow terminal (15), and the control terminal (16) are connected via the safety circuit (12); In an overcurrent state, the safety circuit (12) is blown; The control terminal (16) is connected to the outflow terminal (15) through a heating element (13) to form a control circuit. In an overvoltage state, the heating element (13) generates heat, and the heat passes through the insulating layer (11) to fuse the safety circuit (12).

2. The three-terminal safety structure according to claim 1, characterized in that: An inlet pad (17) and an outlet pad (18) are respectively provided at the bottom of both sides of the insulating layer (11); the safety circuit (12) is provided between the inlet terminal (14) and the outlet terminal (15); and the safety circuit (12) is electrically connected to the inlet terminal (14) and the outlet terminal (15) through the inlet pad (17) and the outlet pad (18).

3. The three-terminal safety structure according to claim 1, characterized in that: A control pad (19) is provided at the bottom of the insulating layer (11); the control terminal (16) is electrically connected to the control pad (19) through the heating element (13); and the control pad (19) is electrically connected to the inflow terminal (14) through the insurance circuit (12).

4. The three-terminal safety structure according to claim 3, characterized in that: Both ends of the heating element (13) are connected to heating end pads (131), and the insulating layer (11) is provided with (131) is a conductive hole (111), one end of the heating element (13) is electrically connected to the control terminal (16) through the conductive hole (111), and the other end of the heating element (13) is electrically connected to the control pad (19) through the conductive hole (111).

5. The three-terminal safety structure according to claim 1, characterized in that: The longitudinal projection of the heating element (13) falls within the longitudinal projection of the safety circuit (12).

6. The three-terminal safety structure according to claim 1, characterized in that: It also includes a solder resist layer (20), which is arranged at the bottom of the insurance circuit (12) and completely covers the The safety circuit (12).

7. The three-terminal safety structure according to claim 1, characterized in that: A protective layer (21) is provided on the top of the support body (10), and the protective layer (21) is used to protect the support body (10).

8. The three-terminal safety structure according to claim 1, characterized in that: The material of the insulating layer (11) is the same as that of the support body (10).

9. The three-terminal safety structure according to claim 1, characterized in that: The safety circuit (12) is an alloy of one or any combination of tin, lead, copper, silver, zinc and aluminum.

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