CN111681845A

CN111681845A - Surface-mounted over-current protection element

Info

Publication number: CN111681845A
Application number: CN202010511351.4A
Authority: CN
Inventors: 方勇; 夏坤; 高道华; 张锐; 吴国臣
Original assignee: Shanghai Wei'an Electronic Co ltd
Current assignee: Shanghai Wei'an Electronic Co ltd
Priority date: 2020-06-08
Filing date: 2020-06-08
Publication date: 2020-09-18

Abstract

The invention discloses a surface-mounted overcurrent protection element, which comprises at least one resistance positive temperature effect conductive composite material core material, wherein at least one surface of the core material is directly covered with a metal electrode; at least one conductive lead member having one end electrically connected to a portion of the core material and the other end electrically connected to a metal electrode; at least one part of the conductive composite material core material and one part of the conductive lead component are wrapped by plastic package and isolated from the external environment. The surface-mounted overcurrent protection element disclosed by the invention is convenient for realizing small-sized production, and meanwhile, the element has higher environmental performance and structural stability.

Description

Surface-mounted over-current protection element

Technical Field

The invention relates to a device used in an electronic circuit and used for overcurrent and overtemperature, in particular to an overcurrent protection element capable of being surface mounted.

Background

The Surface Mounted Device (SMD) prepared by the conductive composite material with the resistance positive temperature effect is widely applied to electronic circuits and plays a role in protecting overcurrent and overtemperature in the electronic circuits. SMD PTC elements are widely used because of their small size and ease of processing. However, with the demand development of miniaturization and integration of electronic circuits, how to realize the 0402 and 0201 packaged SMD PTC element with smaller size, more stable structure and more reliable performance is a technical problem.

Application No. 201721107630.4 relates to a surface-mounted polymer ptc (positive temperature coefficient) overcurrent protection device with excellent environmental stability, which uses a conductive polymer composite material as a main material. Has the following characteristics: a certain buffer groove is designed at the end, close to the welding conductive through hole, of the conductive electrode of the element, and plays a role in buffering welding stress generated after the PTC is welded to the PCB, so that the environmental reliability of the product is improved.

The prior SMD PTC element is mainly formed by processing a PCB, and the SMD PTC element with large size (more than 0603) prepared by adopting the traditional processes of drilling, etching and the like in the PCB still has enough structural strength and reliable electric core after reflow soldering. But for smaller size packages such as 0402, 0201, and even 01005, it is a technical challenge how to achieve stable structural and reliable environmental characteristics when subjected to high temperature reflow soldering processes.

Disclosure of Invention

The invention aims to provide a surface-mounted overcurrent protection element, which can realize smaller-size packaging, and has more stable product structure and more reliable performance.

Another object of the present invention is to: a method for manufacturing a surface-mounted over-current protection element is provided.

The purpose of the invention is realized by the following scheme: the utility model provides a surface mounting overflows excessive temperature protection component, includes electrically conductive combined material core of resistance positive temperature effect, metal electrode and plastic envelope, wherein:

(a) at least one resistance positive temperature effect conductive composite material core material, and at least one surface is directly covered with a metal electrode foil;

(b) at least one conductive lead member having one end electrically connected to a portion of the core material and the other end electrically connected to a metal electrode foil;

(c) the plastic package wraps at least one part of the conductive composite material core material and one part of the conductive lead component, the plastic package is one of hot-melt type or thermosetting type epoxy resin, phenolic resin, polyimide, unsaturated polyester, glass fiber or inorganic filler modified epoxy resin, glass fiber or inorganic filler modified phenolic resin, glass fiber or inorganic filler modified polyimide, glass fiber or inorganic filler modified unsaturated polyester, and the plastic package is formed by compression molding, injection molding, transfer molding or thermosetting.

The plastic packaging material used for surface mounting of the overcurrent protection element is solid epoxy resin, phenolic resin, polyimide, unsaturated polyester, glass fiber or inorganic filler modified epoxy resin, glass fiber or inorganic filler modified phenolic resin, glass fiber or inorganic filler modified polyimide, glass fiber or inorganic filler modified unsaturated polyester which can be processed by hot melting. Or,

the plastic package material used for surface mounting of the overcurrent protection element is thermosetting liquid epoxy resin, phenolic resin, polyimide, unsaturated polyester, glass fiber or inorganic filler modified epoxy resin, glass fiber or inorganic filler modified phenolic resin, glass fiber or inorganic filler modified polyimide, glass fiber or inorganic filler modified unsaturated polyester.

The plastic package wraps at least one part of the conductive composite material core material and one part of the conductive lead component, and the plastic package process is any one of compression molding, injection molding, transfer molding or thermosetting molding.

The core material with the resistance positive temperature coefficient characteristic is at least formed by mixing and processing a high polymer material and a conductive filler, the high polymer material is selected from one of polyethylene, chlorinated polyethylene, oxidized polyethylene, polyvinyl chloride, butadiene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer, polystyrene, polycarbonate, polyamide, polyethylene terephthalate, polybutylene terephthalate, polyphenyl ether, polyphenylene sulfide, polyformaldehyde, phenolic resin, polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, polytrifluoroethylene, polyvinyl fluoride, maleic anhydride grafted polyethylene, polypropylene, polyvinylidene fluoride, epoxy resin, ethylene-vinyl acetate copolymer, polymethyl methacrylate, ethylene-acrylic acid copolymer and a mixture thereof.

The conductive filler is selected from one of carbon black, graphite, carbon fiber, carbon nano tube, metal powder, conductive ceramic powder and a mixture thereof. The metal powder is selected from: one of copper, nickel, cobalt, iron, tungsten, tin, lead, silver, gold, platinum or alloys thereof, and mixtures thereof. The conductive ceramic powder is selected from: one or more of metal nitride, metal carbide, metal boride and metal silicide.

On the basis of the scheme, the conductive lead part can be a metal conductive structure component or consists of at least two of metal electrode foil, a metal coating, a through hole, a blind hole, a solder ball and a conductive bonding pad.

On the basis of the scheme, the outermost layer of the non-welding surface of the element is added with an insulating layer, a metal foil layer or any combination layer of the insulating layer and the metal foil layer to enhance the strength of the element.

On the basis of the scheme, an insulating layer is added between the element bonding pad and the metal electrode foil to enhance the element strength.

The present invention also provides a method for manufacturing a surface-mount overcurrent protection element according to claim 6, comprising the steps of:

preparing a PTC plate with one surface covered with a metal electrode foil through a pressing or integrated pressing molding process;

step two, processing the needed groove by drilling, cutting and ablating processes;

step three, filling the plastic package into the groove in a leveling curing, injection molding, molding and mould pressing mode, and coating the four sides of the core material to finish the groove packaging process;

fourthly, covering a lower metal electrode foil on one surface of the exposed PTC core material, and preparing a hollow hole or a hollow groove 340' for placing the conductive piece through the processes of drilling, punching and slotting;

step five, forming metal conductive parts on the inner walls of the hollow holes or the hollow grooves by the processes of deposition, electroplating, sputtering, spraying or direct insertion of conductive wires;

sixthly, etching, ablating and drilling the surface of the second-time pressed lower metal electrode foil to prepare a cutting channel and an insulating seam, wherein the upper metal electrode foil 121 is connected with a second lower metal electrode foil separated by the isolation seam through a conductive piece, and the two parts of the lower metal electrode foil separated by the isolation seam are used as bonding pads;

and step seven, plating the position of the bonding pad to ensure that the bonding pad of the surface mounting element is higher than the covered lower metal electrode foil.

The core material with the resistance positive temperature effect is prepared by the following method:

adding a high polymer material, a conductive filler and other additives or auxiliary fillers into mixing equipment, and kneading and melt-mixing the materials at a temperature higher than the melting temperature of the high polymer material, wherein the mixing equipment can be one or more of a torque rheometer, an internal mixer, an open mill, a single-screw extruder or a double-screw extruder; and then processing the mixed polymer mixture into a sheet PTC core material with the thickness of 0.10-0.55 mm.

Sheet material, can be achieved by extrusion, compression molding or a thin pull tab of a mill. Preferably, the thickness is 0.12 to 0.45mm, more preferably 0.15 to 0.40mm for the convenience of processing.

The core material can generally improve the stability of the performance of the PTC chip by means of crosslinking or heat treatment.

The crosslinking may be chemical crosslinking or radiation crosslinking, e.g. by means of crosslinking promoters, electron beam irradiation or Co⁶⁰Irradiation is carried out. The radiation dose required by the PTC element is generally less than 100Mrad, preferably 1-50 Mrad, and more preferably 1-20 Mrad.

The heat treatment may be annealing, thermal cycling, high and low temperature alternation, such as 80 deg.C/40 deg.C high and low temperature alternation. The temperature environment for the annealing may be any temperature below the decomposition temperature of the PTC material layer substrate, such as high temperature annealing above the melting temperature of the conductive composite substrate and low temperature annealing below the melting temperature of the conductive composite substrate.

The invention has the advantages that: the surface-mounted overcurrent protection element disclosed by the invention is convenient for realizing small-sized production, and meanwhile, the element has higher environmental performance and structural stability.

Drawings

FIG. 1 is a schematic cross-sectional view of a surface-mounted over-current/over-temperature protection device in accordance with example 1;

fig. 2 is a perspective view of the surface mount over-current and over-temperature protection device 100 according to the embodiment;

FIG. 3 is an exemplary process flow for manufacturing the example of FIG. 1;

FIG. 4 is a schematic diagram of an exemplary process for making the example of FIG. 1;

FIG. 5 is a schematic structural diagram of a surface mount over-current and over-temperature protection device of example 2, which is implemented by the process flow described in FIG. 3;

FIG. 6 is a schematic structural diagram of a surface-mount over-current and over-temperature protection device according to example 3, which is implemented by the process flow described in FIG. 3;

FIG. 7 is a schematic structural diagram of a surface-mount over-current and over-temperature protection device according to example 4, which is implemented by the process flow described in FIG. 3;

fig. 8 is a schematic structural diagram of the surface mount over-current and over-temperature protection device of example 5, which is implemented through the process flow described in fig. 3.

Detailed Description

The present invention will be described in further detail with reference to specific examples.

Example 1

In this embodiment, as shown in fig. 1 and fig. 2, which are schematic cross-sectional views of a structure of a surface-mounted over-current and over-temperature protection device 100, an upper metal electrode foil 121 is coated on the upper surface of a PTC core 110, and

metal electrode foils

122a and 122b which are coated on the lower surface and processed into bonding pads are provided; meanwhile, plastic package materials 130, such as a left plastic package 130a and a right plastic package 130b, are arranged around the PTC core 110; a conductive part 140 is disposed in the right plastic package, the conductive part 140 may be a metal wire, a metal member, or a hole plated with a conductive metal, and fig. 2 is a perspective view of the surface mount over-current over-temperature protection device 100 according to this embodiment.

Referring to fig. 3, a manufacturing flow chart is shown, and fig. 4 shows a structure of a device for completing the steps:

the preparation process of the PTC core material is as follows:

the high molecular material and the conductive filler are used according to the resistance positive temperature effect composite material layer. Setting the temperature of a torque rheometer at 180 ℃, setting the rotation speed at 30 revolutions per minute, adding a polymer, mixing for 1 minute, adding a conductive filler, then continuously banburying for 20 minutes to obtain a conductive composite material, and thinly passing the conductive composite material subjected to melt mixing through a pull tab by using an open mill to obtain the conductive composite material with the thickness of 0.40-0.45 mm, namely the PTC core material 110, as shown in FIG. 4 a;

one surface of the PTC core material 110 is covered with a metal electrode foil 121, and the metal electrode foil 121 is subjected to a pressing or integral pressing molding process to prepare a PTC sheet material with at least one surface covered with the metal electrode foil, as shown in fig. 4 b;

machining the desired trench 130' by a process such as drilling, scribing, ablating, etc., as shown in FIG. 4 c;

filling the plastic package 130 into the groove 130' by means of leveling and curing, injection molding, die pressing and the like, and coating four sides of the PTC core material 110 to complete groove packaging, as shown in fig. 4 d;

covering another metal electrode foil 122 on one surface of the exposed PTC core material 110, and performing a secondary press-fitting, wherein the structure is shown in fig. 4 e;

preparing a hollow hole or a hollow groove 140' capable of accommodating the conductive piece through processes of drilling, punching, slotting and the like, as shown in fig. 4 f;

forming a metal conductive member 140 on the inner wall of the hollow hole or the hollow groove 140' by deposition, electroplating, sputtering, spraying, etc., as shown in fig. 4 g;

etching, ablating, drilling and cutting the surface of the second pressed metal electrode foil 122 to prepare a cutting channel 150 and an insulating seam 150 ', so that the other metal electrode foil 122 is divided into a first bonding pad 122a and a second bonding pad 122b by the insulating seam 150', as shown in fig. 4 (h);

the metal conductive member 140 is used to connect the metal electrode foil 121 and the second bonding pad 122b, and as shown in fig. 1 and 2, plating is performed at the bonding pad position, so that the bonding pad of the surface mount component is higher than the other metal electrode foil 122.

In fig. 1 and 4, the PTC core material 110 is shown, according to the actual process requirements, by placing the PTC core material 110 above a metal electrode foil 121 or between two metal electrode foils 121, 122 that are symmetrical up and down, the metal electrode foil having at least one rough surface, and the rough surface being in direct contact with the PTC core material 110. And then, the PTC core material 110 and the metal electrode foils 121 and 122 are tightly combined together by a hot pressing method, the temperature of the hot pressing is 180 ℃, the PTC core material is preheated for 5 minutes, then the PTC core material is slightly pressed for 3 minutes under the pressure of 5MPa, then the PTC core material is hot pressed for 10 minutes under the pressure of 12MPa, and then the PTC core material is cold pressed for 8 minutes on a cold press to prepare the PTC sheet material at least one surface of which is covered with the metal foil.

Example 2

In this embodiment, as shown in fig. 5, which is a schematic cross-sectional view of a structure of a surface-mounted over-current over-temperature protection device 200, similar to the preparation steps and structure of the embodiment, an upper metal electrode foil 221 is coated on the upper surface of a PTC core material 210, and a lower metal electrode foil 222 is coated on the lower surface of the PTC core material 210; meanwhile, plastic packages are arranged around the PTC core material 210, such as a left-end plastic package 230a, a right-end plastic package 230b, and a bottom plastic package 230 c; the PTC core material 210 is isolated from the external environment by the left and right end plastic packages 230a and 230b, and the lower metal electrode foil 222 is isolated from the external environment by the bottom plastic package 230c, so that the product structural rigidity of the element is increased, the short circuit between the lower metal electrode foil 222 and soldering tin paste is avoided during reflow soldering, and the soldering reliability of the product is improved. In addition, compared with embodiment 1, the conductive member 241 is arranged in the bottom mold 230c, the conductive member 241 is used as the first bonding pad, the conductive member 242 is arranged in the right mold 230b, the top of the conductive member 242 is connected with the upper metal electrode foil 221, and the bottom is used as the second bonding pad, so that the welding stress existing when the metal-clad electrode foil is used as the bonding pad during welding is reduced, and the product reliability is improved.

Example 3

In this embodiment, as shown in fig. 6, which is a schematic cross-sectional view of a structure of a surface-mounted over-current and over-temperature protection device 300, an upper metal electrode foil 321 is coated on the upper surface of a PTC core material 310, and a lower metal electrode foil 322 is coated on the lower surface; meanwhile, plastic packages 330 are arranged around the PTC core material 310, such as a left-end plastic package 330a, a right-end plastic package 330b, an upper plastic package 330d, and a bottom plastic package 330 c; the PTC core material 310 is isolated from the external environment by the left and right

end plastic packages

330a, 330b, and the upper metal electrode foil 321 and the lower metal electrode foil 322 are isolated from the external environment by the upper plastic package 330d and the bottom plastic package 330c, respectively, thereby improving the reliability of the product. In this embodiment, compared to embodiment 2, the upper mold 330d, the metal-clad electrode foil 323, and the conductive member three 343 built in the upper mold 330d are added, the metal-clad electrode foil 323 and the upper metal electrode foil 321 are electrically connected by the conductive member three 343, and the conductive member two 342 as the pad two is electrically connected to the metal-clad electrode foil 323.

Example 4

Fig. 7 is a schematic cross-sectional view of a structure of a surface-mounted over-current and over-temperature protection device 400, in which an upper metal electrode foil 421 is coated on the upper surface of a PTC core material 410, and a lower metal electrode foil 422 is coated on the lower surface; meanwhile, plastic package materials are arranged around the core material 410, such as a left-end plastic package 430a, a right-end plastic package 430b, an upper plastic package 430d and a bottom plastic package 430 c; the PTC core material 410 is isolated from the external environment by the left and right

end plastic packages

430a, 430b, and the upper metal electrode foil 421 and the lower metal electrode foil 422 are isolated from the external environment by the upper plastic package 430d and the bottom plastic package 430c, respectively, so that the reliability of the product is improved. A conductive part I441 is arranged in the bottom plastic package 430c and is used as a bonding pad I; a second conductive part 442 is arranged in the right-end plastic package 430b and serves as a second bonding pad; in this embodiment, compared to embodiment 3, the second conductive part 442 has a U-shaped overall structure, and is directly connected to the upper surface of the upper metal electrode foil 421 to form an electrical connection.

Example 5

Fig. 8 shows a schematic cross-sectional view of a structure of a surface-mounted over-current and over-temperature protection device 500, in which an upper metal electrode foil 521 is coated on the upper surface of a PTC core 510, and a lower metal electrode foil 522 is coated on the lower surface; meanwhile, plastic package materials are arranged around the PTC core material 510, such as a left-end plastic package 531a, a right-end plastic package 531b, an upper plastic package 531d and a bottom plastic package 531 c; the PTC core material 510 is isolated from the external environment by the left and right end plastic packages 531a and 531b, and the upper metal electrode foil 521 and the lower metal electrode foil 522 are isolated from the external environment by the upper plastic package 531d and the bottom plastic package 531c, respectively, so that the reliability of the product is improved; a first conductive part 541 is arranged in the lower-end plastic package 731c and serves as a first bonding pad; a second conductive part 542 is arranged in the right plastic package 530b, and forms a conducting loop with the third, fourth and 544 conductive parts, and the conducting loop is directly communicated with the upper surface of the upper metal electrode foil 521 to form electrical conduction; in this embodiment, compared to embodiment 4, the outer layer plastic 532 is additionally provided on the upper surfaces of the upper plastic 531d and the second conductive component 542, so as to coat and protect the exposed second, third, fourth, 542, 543, and 544 conductive components, thereby reducing the risk of oxidation or external force damage of the conductive components in subsequent applications.

While the foregoing has been disclosed with respect to certain specific embodiments thereof, the foregoing description is illustrative only or is not intended to be exhaustive of the invention, and various alternatives and modifications can be devised by those skilled in the art based on the teachings and teachings herein without departing from the invention. Therefore, the scope of the present invention should not be limited to the disclosure of the embodiments, but should include all combinations of the contents embodied in different parts, and various substitutions and modifications without departing from the present invention.

Claims

1. The utility model provides a surface mounting overflows excessive temperature protection component, includes electrically conductive combined material core of resistance positive temperature effect, metal electrode and pad, its characterized in that:

(a) at least one resistance positive temperature effect conductive composite material core material, and at least one surface of the core material is directly covered with a metal electrode foil;

(c) and plastic package, wherein the plastic package wraps at least one part of the conductive composite material core material and one part of the conductive lead component, is one of hot-melt or thermosetting epoxy resin, phenolic resin, polyimide, unsaturated polyester, glass fiber or inorganic filler modified epoxy resin, glass fiber or inorganic filler modified phenolic resin, glass fiber or inorganic filler modified polyimide, glass fiber or inorganic filler modified unsaturated polyester, and is formed by compression molding, injection molding, transfer molding and thermosetting.

2. The surface mount over-current protection device as claimed in claim 1, wherein the conductive lead member is a metal conductive structure component or is composed of at least two of metal electrode foil, metal plating, through hole, blind via, solder ball, and conductive pad.

3. The surface mount overcurrent protection component of claim 1, wherein the outermost non-solder side of the component is reinforced by an insulating layer, a metal foil layer, or any combination thereof.

4. The surface-mount overcurrent protection component as set forth in claim 1, wherein an insulating layer is added between the component pad and the metal electrode foil to enhance component strength.

5. The surface-mounted overcurrent protection element according to any one of claims 1 to 4, wherein an upper metal electrode foil is coated on an upper surface of the PTC core material 110, and a lower metal electrode foil is coated on a lower surface thereof; meanwhile, the periphery of the core material is provided with a plastic package material, a conductive part is arranged in the plastic package at one end and is electrically conducted with the upper metal electrode foil 121, the lower metal electrode foil is divided into a first metal electrode foil and a second metal electrode foil of the bonding pad by an insulation seam, and the second metal electrode foil is electrically conducted with the upper metal electrode foil through the conductive part.

6. The surface-mounted overcurrent protection component according to any one of claims 1 to 4, wherein an upper metal electrode foil is coated on an upper surface of the core material, and a lower metal electrode foil is coated on a lower surface of the core material; meanwhile, plastic package is arranged at the periphery and the bottom of the core material; the left end plastic package and the right end plastic package isolate the core material from the external environment, the lower end plastic package isolates the lower metal electrode foil 222 covered on the lower surface from the external environment, short circuit between the metal electrode foil covered on the lower surface and soldering tin paste is avoided during reflow soldering, and a conductive part is arranged in the bottom plastic package and serves as a first bonding pad; meanwhile, a conductive part is arranged in the plastic package at one end, the top of the conductive part is electrically connected with the upper metal electrode foil, and the bottom of the conductive part is used as a second bonding pad.

7. The surface mount overcurrent protection component of claim 6, wherein the upper metal electrode foil has an upper end encapsulated and a metal electrode foil coated on an upper surface thereof, a second conductive member is disposed in the upper end encapsulation, the metal electrode foil coated and the upper metal electrode foil are electrically connected through the second conductive member, a top of the first conductive member is electrically connected to the metal electrode foil coated, and the other end of the first conductive member serves as a second bonding pad.

8. The surface-mounted overcurrent protection element according to any one of claims 1 to 4, wherein an upper metal electrode foil is coated on an upper surface of the PTC core material, and a lower metal electrode foil is coated on a lower surface of the PTC core material; meanwhile, plastic packaging is arranged on the periphery of the core material, such as left end plastic packaging, right end plastic packaging, top plastic packaging and bottom plastic packaging; the core material is isolated from the external environment by the left-end plastic package and the right-end plastic package, the upper metal electrode foil covered on the upper surface and the lower metal electrode foil covered on the lower surface are isolated from the external environment by the top plastic package and the bottom plastic package respectively, and a conductive part is arranged in the bottom plastic package and serves as a first bonding pad; meanwhile, a U-shaped conductive component is arranged in the plastic package at one end, one end of the U-shaped conductive component is electrically connected with the upper metal electrode foil, the other end of the U-shaped conductive component is used as a second bonding pad, and the top surface of the U-shaped conductive component is arranged outside the plastic package at the top.

9. The surface-mounted overcurrent protection element according to any one of claims 1 to 4, wherein an upper metal electrode foil is coated on an upper surface of the PTC core material, and a lower metal electrode foil is coated on a lower surface of the PTC core material; meanwhile, plastic package materials are arranged on the periphery of the PTC core material, and the plastic package materials comprise a left-end plastic package, a right-end plastic package, an upper plastic package and a bottom plastic package; the PTC core material is isolated from the external environment by the left-end plastic package and the right-end plastic package, and the upper metal electrode foil and the lower metal electrode foil are isolated from the external environment by the upper plastic package and the bottom plastic package respectively; a first conductive part is arranged in the lower-end plastic package and serves as a first bonding pad; a second conductive part is arranged in the right-end plastic package, and forms a conducting loop with the third conductive part and the fourth conductive part, and the conducting loop is directly communicated with the upper surface of the upper metal electrode foil; and the upper surfaces of the upper plastic package and the second conductive part are provided with an outer plastic package, and the exposed conductive part is wrapped in the outer plastic package.

10. The method for manufacturing a surface-mount overcurrent protection component according to claim 6, comprising the steps of:

preparing a PTC plate-shaped core material with one surface covered with a metal electrode foil through a pressing or integrated pressing molding process;

fourthly, coating a lower metal electrode foil on one surface of the exposed PTC core material, and preparing a hollow hole or a hollow groove for placing the conductive piece through the processes of drilling, punching and slotting;

sixthly, etching, ablating and drilling the surface of the second-time pressed lower metal electrode foil to prepare a cutting channel and an insulating seam, wherein the upper metal electrode foil is connected with a second lower metal electrode foil separated by the isolation seam through a conductive piece, and the two parts of the lower metal electrode foil separated by the isolation seam are used as bonding pads;

11. The method for manufacturing a surface-mounted overcurrent protection component according to claim 10, wherein the core material with the resistance positive temperature effect is prepared by the following method:

adding a high polymer material, a conductive filler and other additives or auxiliary fillers into mixing equipment, kneading and melting and mixing at a temperature higher than the melting temperature of the high polymer material, wherein the mixing equipment is one or more of a torque rheometer, an internal mixer, an open mill, a single-screw extruder and a double-screw extruder; and processing the mixed polymer mixture into a PTC core material with the thickness of 0.10-0.55 mmm.

12. The method for manufacturing a surface-mount overcurrent protection component according to claim 10 or 11,

the PTC core material is placed above a metal foil or between two metal foils which are symmetrical up and down, the metal foil is provided with at least one rough surface, the rough surface is in direct contact with the conductive composite material sheet, the conductive composite material sheet and the metal foil are tightly combined together by a hot pressing method, the temperature of hot pressing is 180 ℃, preheating is carried out for 5 minutes, then micro pressing is carried out for 3 minutes under the pressure of 5MPa, hot pressing is carried out for 10 minutes under the pressure of 12MPa, and then cold pressing is carried out on a cold press for 8 minutes to prepare the PTC core material with at least one surface covered with the metal electrode foil.

13. The method for manufacturing a surface-mounted overcurrent protection component according to claim 12, wherein a groove is formed in the PTC core material by an ablation, drilling, and stamping process, and then a hot-melt or liquid plastic molding material is spread over the groove and cured; after solidification, covering metal electrode foil and pressing, and then preparing a single overcurrent over-temperature protection element capable of being surface-mounted by etching, drilling, electroplating and cutting processes.