TW201320114A - Thermistor - Google Patents

Abstract

A thermistor includes a laminar resistive device, a first insulation layer, a first electrode, a second electrode and a first heat-conductive layer. The resistive device includes a first electrically conductive member, a second electrically conductive member and a polymer layer disposed therebetween. The polymer layer exhibits positive temperature coefficient (PTC) or negative temperature coefficient (NTC) behavior. The first insulation layer is disposed on the first electrically conductive member. The first electrode is electrically coupled to the first electrically conductive member, whereas the second electrode is electrically coupled to the second electrically conductive member and is insulated from the first electrode. The first heat-conductive layer is disposed on the first insulation layer, and has a heat conductivity of at least 30W/m-K and a thickness of 15-250 μ m.

Description

Thermistor element

The present invention relates to a surface mount type (SMD) variable thermistor element made of a conductive polymer material, such as a positive temperature coefficient (PTC) element and a negative temperature coefficient (NTC) element, which can be applied to a printed circuit board ( On the PCB), it has been tested for current protection and abnormal temperature environment.

Since the resistance of the conductive composite material having positive temperature coefficient (PTC) characteristics is sensitive to temperature changes, it can be used as a material of current sensing elements, and has been widely used as an overcurrent protection element or circuit element. on. Since the resistance of the PTC conductive composite at normal temperatures can be maintained at a very low value, the circuit or battery can operate normally. However, when an over-current or over-temperature phenomenon occurs in a circuit or battery, the resistance value is instantaneously increased to a high resistance state (at least 10 ² Ω or more), and excess current is generated. Reduced for the purpose of protecting the battery or circuit components.

In the design and manufacture of high-density circuits, the requirements for the size of the protective components must be light, thin and small, and the surface-adhesive components must be designed for installation. Therefore, PTC elements made of organic polymer materials have been designed into different types of surface-adhesive electronic components. However, due to factors such as component size limitations and poor heat transfer, the hold current of the product cannot be improved. In addition, due to the high thermal insulation of the components, the sensitivity to ambient temperature may be too low.

In order to overcome the above design flaws, the invention is characterized in that the surface of the thermistor element is increased in thermal conductivity for rapid thermal conduction. This increases the holding current of the component and increases the temperature sensing for the environment.

According to an embodiment of the invention, the thermistor element comprises a thin plate type resistive element, a first insulating layer, a first electrode, a second electrode, and a first heat conducting layer. The thin plate type resistive element comprises a first conductive member, a second conductive member and a polymer material layer, wherein the polymer material layer is stacked between the first conductive member and the second conductive member and has a positive temperature or a negative temperature The behavior of the coefficient. The first insulating layer is disposed on the first conductive member, and a surface of the first insulating layer extends to form a first plane. The first electrode electrically connects the first conductive member. The second electrode electrically connects the second conductive member and is electrically isolated from the first electrode. The first heat conducting layer is disposed on the surface of the first insulating layer, and has a thermal conductivity of at least 30 W/m-K, and the first heat conducting layer has a thickness of 15 to 250 μm. In one embodiment, a portion of the first electrode and the second electrode are formed on the first plane, and the first heat conductive layer forms a first surface of the thermistor element, and the first electrode and the second electrode in the first surface The sum of the areas of the first heat conducting layer is 40 to 90% of the area of the first surface.

In one embodiment, the thermistor element further comprises a second insulating layer and a second heat conducting layer, the second insulating layer is disposed on the second conductive member, and a surface of the second insulating layer extends to form a second plane. a second heat conducting layer is disposed on the surface of the second insulating layer, wherein a portion of the first electrode and the second electrode are formed on the second surface, and the second heat conducting layer forms a second surface of the thermistor element, and the first surface The sum of the areas of the first electrode, the second electrode and the second heat conducting layer in the two surfaces is 40 to 90% of the area of the second surface.

In one embodiment, the first conductive member and the first heat conductive layer, or the second conductive member and the second heat conductive layer may be connected by a heat conductive connection.

The invention improves the heat transfer area of the component or the heat conduction/conductivity path by improving the appearance of the conventional SMD product, and can also be matched with the solder pad having the heat transfer effect, thereby greatly improving the heat transfer efficiency of the component, thereby improving the maintenance of the product. Current. In addition, the present invention can also increase sensitivity to ambient temperatures to provide battery component protection and a variety of electronic product applications.

The above and other technical contents, features, and advantages of the present invention will become more apparent from the following detailed description. A schematic diagram of the thermistor. FIG. 1B is a top view of the thermistor element of FIG. 1. FIG. The thermistor 10 includes a thin plate type resistive element 11, a first insulating layer 15, a second insulating layer 16, a first electrode 17, and a second electrode 18. The thin-plate type resistive element 11 includes a first conductive member 12, a second conductive member 13 and a polymer material layer 14, wherein the polymer material layer 14 is stacked between the first conductive member 12 and the second conductive member 13, wherein Contains conductive particles and has a positive or negative temperature coefficient behavior. Polymer materials suitable for use in the present invention include polyethylene, polypropylene, polyfluoroolefin, mixtures of the foregoing, and copolymers. The conductive particles may be metal particles, carbonaceous particles, metal oxides, metal carbides, or a mixture of the foregoing. The first insulating layer 15 is disposed on the first conductive member 12, and the second insulating layer 16 is disposed on the second conductive member 13. The insulating layers 15, 16 may comprise polypropylene, fiberglass or a heat dissipating material. The heat dissipating material is a polymer material comprising a thermosetting plastic and a fiber, and a polymer material having a thermoplastic plastic and a thermosetting plastic cross-penetrating structure, which is disclosed in the Republic of China Patent Publication No. 200816235, Announcement No. 1339088 and Publication No. 201101342, which is incorporated herein by reference. Wherein the polymer heat dissipating material has a thermal conductivity of at least 0.5 W/m-K, and 1 W/m-K, 2 W/m-K, 3 W/m-K, 4 W/m-K or 5 W/m-K or more is a preferred embodiment of the invention.

The first electrode 17 is partially disposed on the first insulating layer 15, that is, formed on the first plane 31 of the surface of the first insulating layer 15. The first electrode 17 includes another portion disposed on the second insulating layer 16, that is, formed on the second plane 32 of the surface of the second insulating layer 16. The first electrode 17 is electrically connected to the first conductive member 12 through the first conductive connection member 19. Similarly, the second electrode 18 includes a portion disposed on the first insulating layer 15 or the first plane 31, and a further portion disposed on the second insulating layer 16 or the second plane 32. The second electrode 18 is electrically connected to the second conductive member 13 through the second conductive connecting member 20 and is electrically isolated from the first electrode 17. In this embodiment, the portion of the first electrode 17 disposed on the surface of the first insulating layer 15 extends toward the second electrode 18 as the first heat conducting layer 21 as compared with the conventional electrode arrangement. Similarly, the portion of the second electrode 18 disposed on the surface of the second insulating layer 16 extends toward the first electrode 17 to form the second heat conducting layer 22. In other words, the first electrode 17 can be considered to include the first heat conductive layer 21, which is an extension of the first electrode 17. The second electrode 18 can be considered to include a second thermally conductive layer 22 that is an extension of the second electrode 18.

The first heat conducting layer 21 and the second heat conducting layer 28 may be made of materials such as nickel, copper, aluminum, lead, tin, silver, gold or alloys thereof having a thermal conductivity greater than 30 W/mK, especially aluminum having a thermal conductivity greater than 200 W/mK. (about 238 W/mK) and more than 300 W/mK of copper (about 397 W/mK), silver, gold, etc. have better heat transfer efficiency, and are a preferred choice for the present invention.

In other words, the upper and lower surfaces of the resistive element 11 are respectively provided with the first conductive member 12 and the second conductive member 13 and each extend to opposite end faces of the thin plate type resistive element 11. The conductive members 12, 13 can be formed from a flat metal film by a general etching method (such as Laser Trimming, chemical etching or mechanical means) to form an upper and lower surface, one left and one right, and an asymmetric notch (the gap generated by the peeling metal film) ). The material of the conductive member may be nickel, copper, zinc, silver, gold, and an alloy or a plurality of layers of the foregoing metals. In addition, the notch may be a rectangular shape, a semicircular shape, a triangular shape or an irregular shape and pattern, and the notch area is preferably not more than 25% of the total area of one side.

After the notch is formed by the peeling metal film, various excellent adhesive films (ie, insulating layers 15, 16 such as a film made of epoxy resin and glass fiber cloth) can be used, and the resistive element 11 and the outer layer are respectively A piece of metal copper film is cured by heat pressing. Thereafter, the copper film of the upper and lower outer layers can be etched to produce electrodes, as shown in FIGS.

The left and right end electrodes 17, 18 can be selectively and vertically connected to the electrodes of the upper, lower, left and right regions by means of the conductive connecting members 19, 20 or the comprehensive cutting surface. The first thermally conductive layer 21 and the first and second electrodes 17, 18, or between the second thermally conductive layer 22 and the first and second electrodes 17, 18 may be electrically isolated by etching. Wherein the interval is at least 15 μm, 20 μm or 30 μm.

In one embodiment, the insulating layer 25 is insulated between the first electrode 17 and the second heat conducting layer 22, and between the second electrode 18 and the first heat conducting layer 21. Although the isolated solder resist layer 25 is rectangular in the present embodiment, other shapes such as semicircular, curved, triangular or irregular shapes and patterns may be suitable for use in the present invention.

The conductive connecting members 19 and 20 in this embodiment are described by taking a semicircular through hole as an example. A layer of conductive metal (such as copper or gold) may be plated on the wall of the via hole by electroless plating or electroplating to achieve the purpose of connecting the upper and lower electrodes. In addition to the semicircular shape, the cross-sectional shape of the via hole may be a circle, a quarter circle, an arc, a square, a diamond, a rectangle, a triangle, or a polygon.

The first electrode 17, the second electrode 18 and the first heat conducting layer 21 formed on the first insulating layer 15 (ie, the first plane 31) form a first surface 24 of the thermistor element 10; formed in the second insulating layer The first electrode 17, the second electrode 18 and the second thermally conductive layer 22 on the layer 16 (i.e., the second plane 32) form a second surface 26 of the thermistor element 10.

The total area of the first electrode 17, the second electrode 18 and the first heat conducting layer 21 in the first surface 24 may be about 40-90%, especially 45-85%, preferably in the total area of the first surface 24. It is 50~80%. In practical applications, the aforementioned percentages may be 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%. Similarly, the total area of the first electrode 17, the second electrode 18, and the second heat conducting layer 22 in the second surface 26 may be about 40-90%, especially 45-85%, of the total area of the second surface 26. Preferably, it is 50 to 80%. In practical applications, the ratio may be 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%.

2A is a schematic view of a thermistor element according to a second embodiment of the present invention. 2B is a top plan view of the thermistor element of FIG. 2A. Similar to the thermistor element 10 shown in FIGS. 1A and 1B, the thermistor element 20 also includes a thin plate type resistive element 11, insulating layers 15 and 16, a first electrode 17, a second electrode 18, and the like. The difference from that shown in FIGS. 1A and 1B is that the first heat conductive layer 21 is not an extension of the first electrode 17, but is provided separately on the first insulating layer 15. The second heat conduction layer 22 is not an extension of the second electrode 18 but is separately provided on the second insulation layer 16. In one embodiment, the first thermally conductive layer 21 is separated from the first and second electrodes 17, 18 by etching or by a solder resist layer 25. The second heat conductive layer 22 and the first and second electrodes 17, 18 may also be separated by etching or may be isolated by the solder resist layer 25. The ratio of the total area of the first electrode 17, the second electrode 18 and the first heat conducting layer 21 to the area of the entire first surface 24 and the sum of the areas of the first electrode 17, the second electrode 18 and the second heat conducting layer 22 occupy the second overall The ratio of the area of the surface 26 can also be referred to in the first embodiment.

3 is a schematic view of a thermistor element according to a third embodiment of the present invention. The thermistor element 30 is provided with a thermally conductive connecting member 27 between the first heat conducting layer 21 and the first conductive member 12 in comparison with the thermistor element 20 shown in FIG. 2A to increase the heat transfer efficiency of the resistive element 11. Similarly, a heat conducting connector 28 may be disposed between the second heat conducting layer 22 and the second conductive member 13. The heat conducting connecting members 27 and 28 can adopt the same material as the heat conducting layers 21 and 22, such as nickel, copper, aluminum, lead, tin, silver, gold or alloy thereof, and the thermal conductivity is greater than 30 W/mK, especially the thermal conductivity is greater than 200 W/ Aluminum of mK and copper, silver, gold or alloys of more than 300 W/mK have the best heat transfer efficiency, and are a preferred choice for the present invention.

The above design and manufacturing method can increase the number of layers of the resistive element to two or more layers (that is, include two or more resistive elements 11) to be connected in parallel to achieve a multilayer parallel type surface resistive resistive element. In addition, the number of the thermally conductive connectors 27 connecting the first heat conducting layer 21 and the first conductive member 12, or the heat conducting connectors 28 connecting the second heat conducting layer 22 and the second conductive member 13 may be plural to increase heat conduction efficiency.

4 is a schematic view of a thermistor element according to a fourth embodiment of the present invention. The thermistor 40 includes a thin plate type resistive element 41, an insulating layer 55, a first electrode 47, and a second electrode 48. The thin plate type resistive element 41 includes a first conductive member 42 , a second conductive member 43 , and a polymer material layer 44 , wherein the polymer material layer 44 is stacked between the first conductive member 42 and the second conductive member 43 , wherein Contains conductive particles and has a positive or negative temperature coefficient behavior. The insulating layer 55 is disposed on the first conductive member 42. The first electrode 47 is electrically connected to the first conductive member 42 through the conductive layer 46. The first electrode 47 is formed on the extending plane 61 of the surface of the insulating layer 55. The second electrode 48 is disposed on the insulating layer 55 (ie, the plane 61), and is electrically connected to the second conductive member 43 through the conductive connection member 49, and is electrically isolated from the first electrode 47. The heat conductive layer 53 is provided on the surface of the insulating layer 55. In one embodiment, the thermally conductive layer 53 is preferably coupled to the first electrically conductive member 42 through a thermally conductive connector 57. The first electrode 47, the second electrode 48 and the heat conducting layer 53 formed on the plane 61 form the surface 51 of the thermistor element 40, and the sum of the areas of the first electrode 47, the second electrode 48 and the heat conducting layer 53 is the surface. The area of 51 is 40 to 90%, especially 45 to 85%, preferably 50 to 80%. In practical applications, the ratio may be 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%.

Other structural types of other surface-adhesive thermistor elements are also disclosed in the Republic of China Patent Publication No. 415624 and the publication number I282696. The related structural forms of the above patents are hereby incorporated by reference. The thermistor elements of the above various structures can be applied with the addition of the heat conducting layer of the present invention or further adding a heat conducting connecting member to increase the heat dissipation effect. In addition, the thickness of the heat conductive layer is between 15 and 250 μm, and may also be 18 μm, 35 μm, 70 μm, 140 μm or 210 μm, wherein the thick thermal layer has a better thermal conductivity.

Compared with the original SMD component architecture, the present invention increases the size of, for example, a copper foil circuit as a heat conducting layer and/or increases the thickness of the heat conducting connector, for example, to form a copper pillar structure, so that when the SMD component is energized, the excess heat source can be conducted to The circuit, or the circuit substrate used. In the case of effectively suppressing the temperature rise, the holding current of the thermistor element can be greatly improved, and the large current demand can be satisfied, and the heat transfer can be improved by the circuit design, and the sensitivity of the element to the external temperature can be effectively improved.

The technical and technical features of the present invention have been disclosed as above, and those skilled in the art can still make various substitutions and modifications without departing from the spirit and scope of the invention. Therefore, the scope of the present invention should be construed as being limited by the scope of the appended claims

10, 20, 30, 40. . . Thermistor element

11. . . Resistance element

12. . . First conductive member

13. . . Second conductive member

14. . . Polymer layer

15. . . First insulating layer

16. . . Second insulating layer

17. . . First electrode

18. . . Second electrode

19. . . First conductive connector

20. . . Second conductive connector

twenty one. . . First heat conducting layer

twenty two. . . Second heat conducting layer

twenty four. . . First surface

25. . . Solder mask

26. . . Second surface

27. . . First thermal connection

28. . . Second thermal connection

31. . . First plane

32. . . Second plane

41. . . Resistance element

42. . . First conductive member

43. . . Second conductive member

44. . . Polymer layer

45. . . Solder mask

46. . . Conductive layer

47. . . First electrode

48. . . Second electrode

49. . . Conductive connector

51. . . surface

53. . . Thermal layer

57. . . Thermal connection

61. . . flat

1A and 1B are schematic views of a thermistor element according to a first embodiment of the present invention;

2A and 2B are schematic views of a thermistor element according to a second embodiment of the present invention;

Figure 3 is a schematic view showing a thermistor element of a third embodiment of the present invention;

Fig. 4 is a schematic view showing a thermistor element of a fourth embodiment of the present invention.

10. . . Thermistor element

11. . . Resistance element

12. . . First conductive member

13. . . Second conductive member

14. . . Polymer layer

15. . . First insulating layer

16. . . Second insulating layer

17. . . First electrode

18. . . Second electrode

19. . . First conductive connector

20. . . Second conductive connector

twenty one. . . First heat conducting layer

twenty two. . . Second heat conducting layer

twenty four. . . First surface

25. . . Solder mask

26. . . Second surface

31. . . First plane

32. . . Second plane

Claims (18)

A thermistor element comprises: a thin plate type resistive element comprising a first conductive member, a second conductive member and a polymer material layer, wherein the polymer material layer is stacked on the first conductive member and the second conductive member And having a positive temperature or a negative temperature coefficient; a first insulating layer disposed on the first conductive member; a first electrode electrically connecting the first conductive member; and a second electrode electrically connecting the first portion And a first conductive layer disposed on the surface of the first insulating layer, having a thermal conductivity of at least 50 W/mK and a thickness of 15 to 250 μm. The thermistor element of claim 1, wherein a surface of the first insulating layer extends to form a first plane, and a portion of the first electrode and the second electrode are formed on the first plane and form a heat sensitive with the first heat conducting layer a first surface of the resistive element, and the sum of the areas of the first electrode, the second electrode and the first heat conducting layer in the first surface is 40 to 90% of the area of the first surface. The thermistor element of claim 1, further comprising a second insulating layer and a second heat conducting layer, wherein the second insulating layer is disposed on the second conductive member, and the second heat conducting layer is disposed on the second insulating layer Layer surface. The thermistor element of claim 3, wherein the surface of the second insulating layer extends to form a second plane, and a portion of the first electrode and the second electrode are formed on the second plane, and form a thermal contact with the second heat conducting layer a second surface of the resistive element, and the sum of the areas of the first electrode, the second electrode and the second heat conducting layer in the second surface is 40 to 90% of the area of the second surface. The thermistor element of claim 3, wherein the first electrode and the second electrode are formed on surfaces of the first insulating layer and the second insulating layer. The thermistor element of claim 1, wherein the first thermally conductive layer is an extended portion of the first electrode. The thermistor element of claim 2, wherein the first heat conducting layer is disposed between the first electrode and the second electrode on the first plane. The thermistor element of claim 1, wherein the first thermally conductive layer is electrically isolated from the first and second electrodes. The thermistor element of claim 8, wherein the first thermally conductive layer is spaced apart from the first or second electrode by at least 15 μm. The thermistor element of claim 1, wherein the first heat conducting layer is isolated from the first and second electrodes by a solder resist layer. The thermistor element of claim 1, wherein the first thermally conductive layer comprises nickel, copper, aluminum, lead, tin, silver, gold or alloys thereof. The thermistor element of claim 1 further comprising a thermally conductive connection member through the first insulating layer, the thermally conductive connector connecting the first thermally conductive layer and the first electrically conductive member. The thermistor element of claim 12, wherein the thermally conductive connector has a thermal conductivity of at least 30 W/m-K. The thermistor element of claim 12, wherein the thermally conductive connector comprises nickel, copper, aluminum, lead, tin, silver, gold or alloys thereof. The thermistor element of claim 1, wherein the first insulating layer comprises polypropylene, fiberglass or a heat dissipating material. The thermistor element of claim 1, wherein the first insulating layer has a thermal conductivity of at least 0.5 W/m-K. The thermistor element of claim 1, further comprising a first conductive connector and a second conductive connector, wherein the first conductive connector is for electrically connecting the first electrode and the first conductive member, and the second conductive connector For connecting the second electrode and the second conductive member. The thermistor element of claim 2, wherein the sum of the areas of the first electrode, the second electrode and the first heat conducting layer in the first surface is 50 to 80% of the area of the first surface.