CN205542231U

CN205542231U - Surface attaching type overcurrent protecting element

Info

Publication number: CN205542231U
Application number: CN201620056026.2U
Authority: CN
Inventors: 杨铨铨; 刘玉堂; 吴国臣; 刘正平; 王军
Original assignee: Shanghai Changyuan Wayon Circuit Protection Co Ltd
Current assignee: Shanghai Weian Electronics Co ltd
Priority date: 2015-02-04
Filing date: 2016-01-20
Publication date: 2016-08-31
Anticipated expiration: 2026-01-20

Abstract

The utility model discloses a surface attaching type overcurrent protecting element, the chip that has resistance positive temperature coefficient effect, include: the electrically conductive combined material basic unit, a conductive electrode, the 2nd conductive electrode that have resistance positive temperature coefficient effect, the chip cladding in the cavity that the adhesive linkage of the frame -shaped construction body and this structure upper and lower portion constitutes, go up conductive welding disk and conductive welding disk down respectively with the upper portion and the sub -unit connection of structure, upper and lower conductive welding disk lies in the left and right sides both sides on the upper and lower surface of structure respectively, and the conductive welding disk length -width ratio is lighter than 10, go up electrically conductive blind hole and at least one electrically conductive blind hole down, the last conductive welding disk of an electrically conductive blind hole electrical connection conductive electrode and upper surface, the conductive welding disk of lower the 2nd conductive electrode of electrically conductive blind hole electrical connection and lower surface, two sides have the electrically conductive end of the electrically conductive end in a left side and a right side, two conductive welding disks about the electrically conductive end electrical connection structure the left side in a left side at least about the structure, two conductive welding disks about the electrically conductive end electrical connection structure the right in the right side. It has solid structure, can have to resist the influence of external extreme environments to over -current protection component performance.

Description

Surface-mounted overcurrent protection element

Technical Field

The present invention relates to a surface mount type overcurrent protection device, and more particularly to a surface mount type overcurrent protection device with a positive temperature resistance effect.

Background

The positive temperature coefficient overcurrent protection element (PTC) based on the conductive composite material is widely applied to the fields of communication, computers, automobiles, industrial control, household appliances and the like, and is applied to overcurrent protection of circuits. In a normal state, the current in the circuit is relatively small, the temperature of the thermistor is low, and when a large current caused by a circuit fault passes through the self-resetting fuse, the temperature of the self-resetting fuse suddenly rises to an 'off' temperature, so that the resistance value of the self-resetting fuse becomes large, and the circuit is in an approximately 'open' state, thereby protecting other elements in the circuit. When the fault is eliminated, the temperature of the thermistor drops, and the resistance value can be restored to a low-resistance state.

With the rapid development of the electronic industry, the market is more and more applying surface-mounted over-current protection elements. The traditional surface mounting type element mounting process is generally reflow soldering, and the thermal process of the process obviously raises resistance of the product. Typically, the lift-off of the component after reflow soldering exceeds 50%. Such a high resistivity rise can significantly affect the retention characteristics of the product for a low resistance PTC protection element.

A surface-mounted over-current protection device disclosed in the application No. 200910248045.X of the applicant comprises two single-layer PTC composite chips, wherein each chip comprises a first PTC core material, a first metal foil layer and a second metal foil layer attached to two surfaces of the first PTC core material, and the other chip comprises a second PTC core material, a third metal foil layer and a fourth metal foil layer attached to two surfaces of the second PTC core material, wherein the second metal foil layer and the third metal foil layer are electrically isolated and bonded by a third insulating layer between the two single-layer PTC composite chips to form a double-layer PTC composite chip, an etching pattern is respectively formed on the upper and lower opposite positions of the first metal foil layer and the fourth metal foil layer at the middle part of the double-layer PTC composite chip to expose the first PTC and the second PTC core materials at the inner sides to form a composite small chip, and the composite small chip is drilled, drilled and coated on the lower part of the composite chip, A surface mount type overcurrent protection element having PTC characteristics is formed by mounting.

The ancient cooking science and technology company is applied to the fields of the application number: 201310203815.5 discloses a surface mount type over-current protection device including a PTC material layer, first and second connecting circuits, first and second electrodes, and an insulating layer. The PTC material layer has a volume resistivity of less than 0.2 omega-cm, and comprises a crystalline high molecular polymer and a conductive filler dispersed therein and having a volume resistivity of less than 500 mu omega-cm. The first and second connection circuits have a function of effectively dissipating heat generated from the PTC material layer. The first electrode is electrically connected to the first surface of the PTC material layer through the first connection circuit. The second electrode is electrically connected to the second surface of the PTC material layer through the second connection circuit. The insulating layer serves to isolate the first and second electrodes. The total area of the electrodes and the connecting circuits is divided by the area of the PTC material layers and the number of the PTC material layers is greater than or equal to 0.6. When the over-current protection element is at 25 ℃, the value of the maintaining current divided by the area and the number of the PTC material layers is more than 1A/mm 2.

The ancient cooking science and technology company is applied to the fields of the application number: 201310204088.4 also discloses a surface-mount over-current protection device comprising at least one PTC material layer, a first conductive layer, a second conductive layer, a first electrode, a second electrode and at least one insulating layer. The PTC material layer contains a crystalline high molecular polymer and a conductive filler dispersed in the crystalline high molecular polymer. The first and second conductive layers are respectively disposed on the first and second surfaces of the PTC material layer. The first and second electrodes are electrically connected to the first and second conductive layers, respectively. The insulating layer is arranged between the first electrode and the second electrode and used for electric isolation. At the melting point temperature corresponding to the crystalline high polymer, the difference between the thermal expansion coefficients of the crystalline high polymer and the first and second conductive layers is more than 100 times, and the thickness of at least one of the first conductive layer and the second conductive layer is large enough to make the resistance reproducibility R3/Ri of the surface mount type over-current protection device less than 1.4, wherein Ri is the initial resistance value of the device, and R3 is the resistance value after 3 times of triggering.

And ancient cooking company, inc, application No. 201310130672.X discloses a surface mount type overcurrent protection element comprising: the PTC material layer, the first and second conductive layers, the first and second electrodes, and the first and second electrical conduction members. The PTC material layer contains crystalline high molecular polymer and conductive filler, and the volume resistivity thereof is less than 0.18 omega-cm. The first and second conductive layers are in physical contact with opposite surfaces of the layer of PTC material, respectively. The first electrode comprises a pair of first metal foils formed on the upper and lower surfaces of the element and electrically isolated from the second conductive layer. The second electrode comprises a pair of second metal foils formed on the upper and lower surfaces of the element and electrically isolated from the first conductive layer. The first electric conduction piece is formed on the first end face and connected with the first metal foil and the first conductive layer. The second electric conduction piece is formed on the second end surface and connected with the second metal foil and the second conductive layer. The first and second conductive members occupy 40% to 100% of the area of the first and second end surfaces, respectively.

In addition, ancient cooking science and technology corporation applies: 201310129361.1 discloses a surface mount type overcurrent protection element comprising: PTC component, first electrode, second electrode, first circuit and second circuit. The PTC element comprises a PTC material layer, a first conductive layer and a second conductive layer. The PTC material layer is disposed between the first conductive layer and the second conductive layer, and comprises crystalline high molecular polymer and conductive filler dispersed therein. The first electrode includes a pair of first metal foils formed on the upper and lower surfaces. The second electrode includes a pair of second metal foils formed on the upper and lower surfaces. The first circuit is electrically connected with the first electrode and the first conducting layer and comprises a first plane line extending along the horizontal direction and a first conducting piece extending along the vertical direction. The second circuit is electrically connected with the second electrode and the second conducting layer and comprises a second horizontal line extending along the horizontal direction and a second conducting piece extending along the vertical direction. Wherein at least one of the first and second planar wires has a thermal resistance sufficient to prevent thermal runaway such that the over current protection device can trigger within 60 seconds under a 25 ℃, 8A test.

In order to solve the problem that after reflow soldering, the high lift-drag ratio of the component exceeds 50%, which affects the product retention characteristics, electronic companies have been designed to try new mounting methods without thermal process, for example, a direct-plug-in type solution of a card housing is adopted, that is, the component is inserted into a card slot, and two spring contacts are respectively pressed on two left and right conductive pads of the component to access the circuit. The scheme can not solve the problem of lift resistance as far as possible, and has the characteristics of simple installation, energy conservation, environmental protection and small damage to a protection element.

A new problem with this solution is that the force with which the spring contact presses on the component must be sufficiently large in order to avoid a low contact resistance. When the element with positive temperature coefficient effect is in action state, the chip is in expansion state, the strength of the material is greatly reduced, and the element is bent by the pressure of the spring contact. This solution therefore requires high mechanical strength for the protective element. The development of protective elements with suitable mechanical strength which meet the requirements of this application has then become a new development in this field.

Electro tomahawk, Dongguan city, application No.: 201310239798.0 and application No. 201320346767.0 disclose a surface-mounted fuse with end without soldering tin and its manufacturing method, which comprises an insulating housing with an accommodating cavity inside, a fuse link arranged in the accommodating cavity, and two metal end caps respectively covering two ends of the housing, wherein two ends of the fuse link respectively extend out of the housing from two ends of the housing and bend towards the end face of the housing to form a connecting part, the two end caps respectively contact with the connecting parts of the corresponding ends and clamp the connecting parts on the end face of the housing, the fuse link and the end caps are connected in close contact, soldering tin is not needed as the connection between the end caps and the fuse link, the poor tin generation of the fuse in the assembling and fusing processes is avoided, meanwhile, the fuse link is fully protected in the insulating housing and the end caps, and has a buffering effect when being impacted by cold and heat, safety and reliability, the consumption of soldering tin is reduced, the material cost and the assembly heating cost are reduced, and the soldering tin can be suitable for high-current products.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a surface mounting type overcurrent protection component of novel structure, it has sturdy structure, can have and resist external extreme environment like light, heat, humidity, oxygen, the influence of power to overcurrent protection component performance.

The purpose of the utility model is realized through the following scheme: a surface-mounted overcurrent protection element, which is a chip with resistance positive temperature coefficient effect, the chip comprises a conductive composite material base layer and an electrode, wherein the conductive composite material base layer comprises at least one polymer and at least one conductive filler uniformly distributed in the polymer, and the surface-mounted overcurrent protection element comprises:

1) the chip with the positive temperature coefficient of resistance effect comprises:

(a) the conductive composite material base layer with the resistance positive temperature coefficient effect has the volume resistivity less than 0.001 omega.m and is provided with an upper surface and a lower surface which are opposite;

(b) a first conductive electrode disposed on an upper surface of the conductive composite base layer;

(c) the second conductive electrode is arranged on the lower surface of the conductive composite material base layer;

2) the chip with resistance positive temperature coefficient effect is coated in a cavity formed by the frame-shaped structure body and the bonding layers on the upper part and the lower part of the structure body, and the upper conductive bonding pad and the lower conductive bonding pad are respectively connected with the upper part and the lower part of the structure body;

3) The upper conductive bonding pad and the lower conductive bonding pad are respectively positioned on the left side and the right side of the upper surface and the lower surface of the structure body, and the length-width ratio of the conductive bonding pads is smaller than 10;

4) the conductive blind holes comprise at least one upper conductive blind hole and at least one lower conductive blind hole, the upper conductive blind hole is electrically connected with the first conductive electrode and the conductive bonding pad on the upper surface, and the lower conductive blind hole is electrically connected with the second conductive electrode and the conductive bonding pad on the lower surface;

5) the conductive end comprises at least one left conductive end and at least one right conductive end, the left conductive end is arranged on the left side of the structure body, and the left conductive end is electrically connected with the upper conductive pad and the lower conductive pad on the left side; the right conductive end is arranged on the right side of the structure body and is electrically connected with the upper conductive pad and the lower conductive pad on the right side.

The utility model discloses introduce the electrically conductive end of frame-shaped structure body and plug-in type, can install inside the interface that charges through the snap-in method, installation simple process has avoided using complicated and the operation process uncontrollable reflow soldering or other welding process to install, has simplified technology, has improved work efficiency.

On the basis of the scheme, the conductive composite material base layer comprises at least one polymer and at least one conductive filler which is uniformly distributed in the polymer, has volume resistivity of less than 2 mu omega, m and has particle size of 0.05-50 mu m. Wherein,

The polymer accounts for 20-75% of the volume fraction of the conductive composite material base layer, and 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, polyphenylene oxide, 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 volume fraction of the polymer in the conductive composite material base layer is preferably 25-70%, and more preferably 30-65%.

The conductive filler is selected from one of 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.

The particle size of the conductive filler is preferably 0.05-50 μm, more preferably 0.1-20 μm; the volume resistivity is not more than 2 mu omega.m, preferably not more than 1 mu omega.m, and more preferably not more than 0.5 mu omega.m. The conductive filler accounts for 25-80% of the volume fraction of the conductive composite material base layer, preferably between 30-75%, more preferably between 35-70%, and is dispersed in the polymer.

The particle size of the conductive filler is preferably 0.05-50 μm, more preferably 0.1-20 μm; the conductive filler accounts for 25-80% of the volume fraction of the conductive composite material base layer, preferably between 30-75%, more preferably between 35-70%, and is dispersed in the polymer.

The conductive composite substrate having the positive temperature coefficient of resistance effect may contain other components such as antioxidants, radiation crosslinking agents (often referred to as radiation promoters, crosslinking agents or crosslinking promoters, e.g., triallyl isocyanurate), coupling agents, dispersants, stabilizers, nonconductive fillers (e.g., magnesium hydroxide, calcium carbonate), flame retardants, arc suppressants or other components. These components typically constitute no more than 15% by volume, for example 5% by volume, of the total volume of the polymer-based conductive composite.

The frame structure is a compound which is composed of fibers or fiber felts as a framework and thermoplastic or thermosetting polymers as cementing materials, and the flexural strength of the compound is 100 MPa-50 GPa.

The bonding layer is a high-thermal conductivity polymer composite material layer with the thermal conductivity coefficient of 0.1-10W/m.K.

The conductive blind hole is formed by drilling and attaching a conductive metal layer on the surface of the hole, and the shape of the conductive blind hole is cylindrical, conical, cuboid, square or other prism, and the like, and can be any shape for electrically connecting the conductive electrode and the conductive pad. The drilling can be mechanical drilling and laser drilling, and the method for attaching the conductive metal layer on the surface of the hole is chemical deposition, spraying, sputtering, electroplating or the combination of the processes.

The frame-shaped structure body is rectangular, and the conductive ends are distributed on the left side and the right side of the frame-shaped structure body. The left conductive end can be distributed at any part of the left end of the cuboid structure; the right conductive end can be distributed at any position of the right end of the cuboid structure.

The number of the left conductive end and the right conductive end is one or more than one respectively.

The conductive blind hole can penetrate through the conductive electrode and penetrate into the conductive composite material base layer, and the connection stability of the conductive blind hole and the chip can be better guaranteed through the connection.

The utility model has the advantages that:

1) the utility model can be directly installed in the charging interface in a card-in mode, avoiding the installation by using reflow soldering or other welding processes which are complex and difficult to control, simplifying the process and improving the working efficiency;

2) functionally, the current can be cut off in time when the current is abnormal and the interface temperature is overhigh until the fault is removed, so that the electronic equipment and the circuit are protected;

3) structurally, under the condition of ensuring the core function, the structure has very good structural strength and can resist the influence of external extreme environments such as light, heat, humidity, oxygen and force on the performance of the over-current protection element.

Drawings

Fig. 1 is a perspective view of a surface mount type overcurrent protection element;

FIG. 2 is a cross-sectional view of a conductive composite chip;

FIG. 3 is a cross-sectional view of the chip after being placed in a frame plate;

FIG. 4 is a cross-sectional view of the structure after the chip has been completely wrapped;

FIG. 5 is a cross-sectional view after formation of blind and through holes;

FIG. 6 is a cross-sectional view after forming conductive blind vias, conductive vias and conductive pads;

FIG. 7 is a cross-sectional view after forming a conductive protection layer;

fig. 8 is a schematic cross-sectional structure diagram of embodiment 2 of the present invention;

fig. 9 is a plan view structural view of embodiment 3 of the present invention;

description of the figures

10-surface mount type overcurrent protection element;

11. 12-first and second quarter vias;

13. 14-third, fourth quarter vias;

20-chip with positive temperature coefficient of resistance effect;

21a, 21 b-first and second conductive electrodes;

22-conductive composite substrate;

30-structure with chip with positive temperature coefficient of resistance effect placed inside;

31-frame-shaped structure;

40-device;

41a, 41 b-upper and lower metal electrode plates;

42a, 42 b-upper and lower adhesive layers;

resulting in 50 as shown in figure 5.

50-a post-drilled structure-reinforced electrically conductive material element;

53a, 53 b-upper and lower blind holes;

60-component with bond pad;

61a, 61b, 61c, 61 d-upper right, upper left, lower right, lower left conductive pads;

63a, 63b — upper and lower conductive blind holes;

64a, 64 b-upper and lower insulation slots;

70-elements forming a conductive protective layer;

73a, 73 b-upper and lower conductive blind holes with protective layers;

75a, 75b, 75c, 75d — protective layer on top right, top left, bottom right, and bottom left conductive pads;

80-example 2 element;

81a, 81 b-laser drilling the upper and lower blind holes;

90-example 3 element;

91a, 91b, 91c, 91 d-Right one, Right two, left one, left two conductive terminals.

Detailed Description

Example 1

As shown in fig. 1, a perspective view of a surface-mount type overcurrent protection device, fig. 2, a sectional view of a conductive composite chip, fig. 3, a sectional view of a chip after being placed in a frame plate, fig. 4, a sectional view of a structure body after the chip is completely wrapped, fig. 5, a sectional view after forming a blind via and a through hole, and fig. 6, a sectional view after forming a conductive blind via, a conductive through hole, and a conductive pad,

the utility model relates to a surface-mounted overcurrent protection element 10, as shown in fig. 1, a first quarter through hole 11 and a second quarter through hole 12 are arranged at two left corners of the element as left conductive ends; a third quarter through hole 13 and a fourth quarter through hole 14 are arranged at the right two corners of the element and are used as right conductive ends;

the surface mount type overcurrent protection element 10 includes a chip 20 having a positive temperature coefficient of resistance effect, wherein,

1) the chip 20 with positive temperature coefficient of resistance effect includes:

(a) A conductive composite base layer 22 having a positive temperature coefficient of resistance effect, as shown in fig. 2, having opposite upper and lower surfaces, a volume resistivity of which is less than 0.001 Ω. m, comprising at least one polymer and at least one conductive filler having a volume resistivity of less than 2 μ Ω. m and a particle size of 0.05 μm to 50 μm uniformly distributed in the polymer;

(b) a first conductive electrode 21a disposed on an upper surface of the conductive composite base layer 22;

(c) a second conductive electrode 21b disposed on a lower surface of the conductive composite base layer 22;

2) the chip 20 with the resistance positive temperature coefficient effect is coated in a cavity formed by the frame-shaped structure body 31 and the upper and lower adhesive layers 42a and 42b of the structure body 31, as shown in fig. 3 and 4, the upper and lower parts of the structure body 30 in which the chip 20 with the resistance positive temperature coefficient effect is placed are respectively connected with the upper conductive pad 41a and the lower conductive pad 41 b;

3) the upper and lower conductive pads are respectively positioned on the left and right sides of the upper and lower surfaces of the structure body, and the length-width ratio of the conductive pads is less than 10;

4) conductive blind vias, as shown in fig. 5, including an upper conductive blind via 53a and a lower conductive blind via 53b, the upper conductive blind via 53a electrically connecting the first conductive electrode 21a and the upper conductive pad 51a, and the lower conductive blind via 53b electrically connecting the second conductive electrode 21b and the lower conductive pad 51 b;

5) As shown in fig. 6, by providing the insulating grooves 64a, 64b in the middle of the upper and lower conductive pads 51a, 51b, the device 60 is formed with the upper and left conductive pads 61a, 61b, and the lower and left conductive pads 61d, 61c, the upper conductive blind via 63a electrically connects the first conductive electrode 21a and the upper right conductive pad 61a of the upper surface, and the lower conductive blind via 63b electrically connects the second conductive electrode 21b and the lower left conductive pad 61d of the lower surface;

the conductive terminal, as shown in fig. 1, includes a left conductive terminal 11 and a right conductive terminal 12, the right conductive terminal 12 is at the right side of the structure and electrically connects the upper right conductive pad 61a and the lower right conductive pad 61 c; the left conductive terminal 11 is located on the left side of the structure and electrically connects the left upper left conductive pad 61b and the left lower conductive pad 61 d.

The specific preparation method comprises the following steps:

first, manufacture of core function chip

The polymer, the conductive filler and the processing aid are mixed according to a proper formula. Setting the temperature of an internal mixer to 180 ℃, setting the rotating speed to 30 r/min, firstly adding a polymer for internal mixing for 3 min, then adding a conductive filler and a processing aid, finishing the addition within 3 min, continuously internal mixing for 15 min, and then discharging to obtain the conductive composite material.

The above-mentioned molten and mixed conductive composite material is rolled by an open mill to obtain a conductive composite material base layer 22 having a thickness of 0.20 to 0.25 mm, as shown in fig. 2.

The conductive composite substrate 22 is disposed between the upper and lower metal foils as shown in fig. 2, and the rough surfaces of the upper and lower metal foils are tightly bonded to the conductive composite substrate 22 to form the first and second electrodes 21a and 21 b. The three layers are stacked and tightly combined together by a hot pressing method. And (3) carrying out hot pressing at the temperature of 180 ℃, under the pressure of 12 MPa for 10 minutes, and finally carrying out cold pressing on the composite material layer on a cold press for 10 minutes to obtain the composite material layer with the positive temperature coefficient of resistance effect shown in the figure 2. And (3) punching the composite material layer into a chip 20 with a proper size and a resistance positive temperature coefficient effect by using punch equipment provided with a punching die. The size of the chip depends on the size of the final product. Typical final product sizes are 0805, 1210, 1206, 1812, 2016, etc.

Second, subsequent processing

The chip 20 with the effect of positive temperature coefficient of resistance is placed in a frame-shaped structure 31 as shown in fig. 3, and a structure 30 with the chip with the effect of positive temperature coefficient of resistance placed therein is manufactured.

For convenience of production, the lower adhesive layer 42b shown in fig. 4 is usually partially adhered to the bottom surface of the frame-shaped structure 31 shown in fig. 4 by multi-point adhesion, and then the chip is placed in the frame-shaped structure 31, so that the chip does not move up and down, and the lower surface is laminated and pressed conveniently; upper and lower metal electrode plates;

As shown in fig. 4, the upper metal electrode sheet 41a, the upper adhesive layer 42a, the chip-mounted structure 30, the lower adhesive layer 42b, and the lower metal electrode sheet 41b are stacked in this order from top to bottom, and then subjected to thermocompression bonding at a temperature of 180 degrees celsius and a pressure of 5 mpa for 120 minutes to form a completed stack as shown in fig. 4. The frame 31 and the upper and lower adhesive layers 42a, 42b completely wrap the chip, and the electrode pads 41a and 41b are tightly attached to the devices 40 on the upper and lower surfaces of the structure.

As shown in fig. 5, blind holes 53a and 53b are drilled in the surfaces of the upper and lower metal electrode pieces 41a and 41b according to pre-designed drilling positions, the number of the blind holes on each surface may be one or more, the drilling depth is optimized by the drill bit completely drilling the upper and lower metal electrode pieces 41a and 41b, the first conductive electrode 21a and the second conductive electrode 21b of the chip, so as to facilitate the upper conductive blind hole 53a and the first conductive electrode 21a of the chip to form a cross-shaped intersection, and the lower conductive blind hole 53b and the second conductive electrode 21b to form a cross-shaped intersection, thereby obtaining the conductive material element 50 with the reinforced structure body after drilling shown in fig. 5.

The conductive material element 50 with the structure reinforced as shown in fig. 5 is subjected to electroless copper plating and spot copper plating to form upper and lower conductive blind holes 63a and 63b, and the upper and lower conductive blind holes 63a and 63b are electrically connected to the upper and lower metal electrode pads 41a and 41b, the first conductive electrode 21a, and the second conductive electrode 21b in a cross shape. Insulating grooves 64a, 64b are etched in the upper and lower metal electrode pads 41a, 41b by a pattern transfer etching technique to obtain upper right, upper left, lower right and lower left conductive pads 61a, 61b, 61c, 61d, and a landed element 60 as shown in fig. 6 is obtained.

Finally, through the chemical plating process, a metal protection layer is plated on the upper right, upper left, lower right, lower left conductive pads 61a, 61b, 61c, 61d, and the upper and lower conductive blind vias 63a, 63b shown in fig. 7, wherein the metal protection layer may be a Ni/Au composite layer or other metal layers capable of playing a role of protection, and has a good conductive capability. Left and right conductive terminals 11, 12 are formed on the left and right of the device, respectively, by drilling 1/4 vias, i.e., first, second, third, and fourth quarter vias 131, 132, 133, 134 at the four corners of the rectangular device. The surface mount type overcurrent protection element 10 shown in fig. 1 is obtained.

Example 2

The structure diagram of the surface-mount overcurrent protection device according to embodiment 2 of the present invention is shown in fig. 8, and its basic steps are the same as those of embodiment 1, except that the process of drilling the blind hole is changed from mechanical drilling to laser drilling. The blind holes 81a and 81b formed by laser drilling are connected to the upper electrodes 21a and 21b of the chips having the positive temperature coefficient of resistance effect, respectively.

Example 3

The top view of the surface mount type overcurrent protection device according to embodiment 3 of the present invention is shown in fig. 9, which is the same as that of embodiment 1 except that the conductive terminals are changed from four conductive holes distributed at four corners to half semicircular holes 91a, 91b, 91c and 91d distributed at the left and right ends.

The disclosure and features of the present invention have been disclosed above, but the invention as described above relates only briefly or only to specific parts of the invention, which may be more features than those disclosed herein. Therefore, the scope of the present invention should not be limited to the disclosure of the embodiments, but should include all combinations of contents embodied in different parts, and various substitutions and modifications without departing from the present invention, and covered by the claims of the present invention.

Claims

1. A surface-mounted over-current protection element has a chip with resistance positive temperature coefficient effect, which comprises a conductive composite material base layer and electrodes,

2. The surface-mount overcurrent protection component according to claim 1, wherein the frame-shaped structure is a composite structure having a skeleton made of fibers or fiber mats and a binder made of a thermoplastic or thermosetting polymer, and has a flexural strength of 100MPa to 50 GPa.

3. The surface-mount overcurrent protection component according to claim 1, wherein the adhesive layer is a high thermal conductivity polymer composite layer having a thermal conductivity coefficient of 0.1-10W/m-K.

4. The surface-mount overcurrent protection component according to claim 1, wherein the conductive blind via is cylindrical, conical, rectangular, or square in shape.

5. The surface-mount overcurrent protection component according to claim 1 or 2, wherein the frame-shaped structure is rectangular, and the conductive terminals are distributed on left and right sides of the frame-shaped structure.

6. The surface-mount overcurrent protection component according to claim 1, wherein the number of the left conductive end and the right conductive end is more than one.

7. The surface-mount type overcurrent protection component as recited in claim 1, wherein the conductive blind via passes through the conductive electrode and extends into the conductive composite substrate.