WO1995024046A1 - Thermistor a coefficient positif de temperature - Google Patents

Thermistor a coefficient positif de temperature Download PDF

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Publication number
WO1995024046A1
WO1995024046A1 PCT/JP1995/000334 JP9500334W WO9524046A1 WO 1995024046 A1 WO1995024046 A1 WO 1995024046A1 JP 9500334 W JP9500334 W JP 9500334W WO 9524046 A1 WO9524046 A1 WO 9524046A1
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WO
WIPO (PCT)
Prior art keywords
electrode layer
layer
aluminum
positive
thermistor
Prior art date
Application number
PCT/JP1995/000334
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English (en)
Japanese (ja)
Inventor
Hiroshi Sasaki
Shu-Ichi Takeda
Original Assignee
Komatsu Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Komatsu Ltd. filed Critical Komatsu Ltd.
Priority to EP95910727A priority Critical patent/EP0749132A4/fr
Publication of WO1995024046A1 publication Critical patent/WO1995024046A1/fr

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C1/00—Details
    • H01C1/14—Terminals or tapping points or electrodes specially adapted for resistors; Arrangements of terminals or tapping points or electrodes on resistors
    • H01C1/1406—Terminals or electrodes formed on resistive elements having positive temperature coefficient

Definitions

  • the present invention relates to a positive temperature coefficient thermistor and a thermistor device using the same, and more particularly to a structure of an electrode thereof.
  • This PTC thermistor can adjust the temperature range with a large positive temperature coefficient by adding Sr, Pb, etc., so that it can measure temperature and prevent overcurrent, It is indispensable in a wide variety of fields, such as circuit elements such as and low-temperature heaters.
  • this type of thermal sintering sinters oxides, carbonates, nitrates, and chlorides of metals such as Ba, Ti, and Nd.
  • a thin silicon body 11 formed into a thin cylindrical shape or the like, and first electrode layers 12a and 12b formed of N i -metal layers formed on the upper and lower surfaces thereof, Second electrode layers 13a and 13b mainly formed of silver and formed in the upper layer.
  • Such a positive characteristic thermistor is usually used by applying a voltage between the second electrode layers 13a and 13b.
  • a so-called migration phenomenon occurs in which silver migrates and precipitates.
  • silver moves in the direction of the electric field on the outer peripheral surface of the positive temperature coefficient thermistor element 1
  • the outer shape of the second electrode layer is larger than the outer shape of the first electrode layer.
  • the first electrode layer which is not covered by the second electrode layer, is directly exposed to the atmosphere, so it is easily oxidized and gradually increases the connection resistance. There was a problem.
  • silver migration is a phenomenon that moves along the direction of the electric field, so even if only the second electrode layer is provided inside the outer periphery as in the conventional example, silver in the second electrode layer is exposed. As a result, migration occurred, albeit slightly, and the short-circuit problem was mitigated but could not be completely prevented.
  • the plating solution permeates into the sintered body when performing Ni plating when forming the electrodes,
  • the characteristics of the sintered body may change, such as a decrease in the resistance value.
  • C This may appear as a characteristic change immediately after formation, or may gradually appear over time.
  • the thermistor applications all require high-precision resistance control, such as temperature measurement and control, compensation, gain adjustment, power measurement, overcurrent prevention, motor startup, color TV degaussing, etc. It is necessary to use those that are within the range of R ⁇ ⁇ %. Therefore, the problem of the change in the resistance value due to the penetration of the plating liquid is becoming more serious.
  • a method has been proposed in which a low melting point metal such as aluminum is formed by metal spraying and used as an electrode.
  • this method also involves an abrupt temperature change at the time of electrode formation, and thus cannot avoid the problem that cracks occur in the thermistor body or the electrode itself.
  • the present inventors have proposed a thermistor electrode structure using a printed electrode or a vapor-deposited film containing aluminum as a main component in Japanese Patent Application Laid-Open No. 6-5403. I have. According to such a structure, since aluminum is a main component, migration is completely prevented. In addition, since a printed or vapor-deposited film is used, the element body does not crack and the durability is improved.
  • the first electrode is made of aluminum or the like, the resistance of the electrode itself becomes large, and there is a serious problem that it is not suitable for a circuit in which a relatively large current flows.
  • a nickel electrode is formed as the first electrode on both surfaces of the thermistor body. Then, a second electrode mainly composed of silver is formed around the gap region, and a third electrode made of aluminum-silicon is formed to cover the gap region.
  • An electrode structure for preventing the cross section has also been proposed (JP-A-5-109503). However, in this structure, unevenness is formed on the surface, and when two elements are used in an overlapping manner, sufficient thermal contact cannot be obtained, so that there is a problem that the residual current is large.
  • the present invention has been made in view of the above circumstances, and provides a positive-characteristic thermistor that has good assembling workability, is stable, has high reliability, can completely prevent migration, and is suitable for a circuit with a large current.
  • the purpose is to do.
  • a first feature of the present invention is that a first layer including a silver layer formed on both main surfaces of the positive temperature coefficient thermistor body so that an end thereof is formed inside the outer peripheral edge of the positive temperature coefficient thermistor body is provided. And a second electrode layer made of a layer mainly composed of aluminum and formed so as to cover the surface and side surfaces of the first electrode layer. Desirably, the second electrode layer is formed of a thick print layer containing conductive boron compound ceramic of 5 to 60 Vo 1% and aluminum.
  • T i B 2 as conductive boron compound used here, Z r B 2, H f B 2, V b B Q, T a B 2, C r B 2 , M o 2 borides such as B 2, T i B, Z r B, H f B, VBN b B, T a B, C r B, Mo B, WB, N i B 1-element boride or V 3 B 4 ,
  • a second feature of the present invention is that a single layer including a silver layer is formed on both main surfaces of the positive temperature coefficient thermistor body so as to have an end inside the outer peripheral edge of the positive temperature coefficient thermistor body. Or a plurality of first electrode layers, and a second electrode layer formed of aluminum as a main component and formed so as to cover a side surface from near an edge of the first electrode layer. That is.
  • a third feature of the present invention is that a single layer including a silver layer is formed on both main surfaces of the positive temperature coefficient thermistor body so that an end is formed inside an outer peripheral edge of the positive temperature coefficient thermistor body. Or a plurality of first electrode layers, a second electrode layer mainly composed of silver formed so as to cover a surface and side surfaces of the first electrode layer, and a second electrode layer. An aluminum layer formed so as to cover the side surface from the vicinity of the edge portion, or a third electrode layer made of a layer containing 5 to 6 Ovol% of a conductive boron compound and aluminum is provided.
  • a fourth feature of the present invention is that a first electrode layer formed on both main surfaces of the positive temperature coefficient thermistor body and an edge formed inside the edge of the first electrode layer are formed.
  • a fifth characteristic of the present invention is that a positive temperature coefficient thermistor and a positive temperature coefficient thermistor formed on both main surfaces of the thermistor body and composed of an electrode whose outermost layer is formed of an aluminum layer are provided. And a terminal that is in contact with the positive temperature coefficient thermistor and is formed of a material that does not form an alloy having a melting point of 300 ° C. or less with aluminum.
  • the material is nickel, silver, copper, aluminum, titanium, or an alloy thereof.
  • the electrodes are formed by a dry process such as a vapor deposition method or a thick film printing method. Therefore, it is possible to form an electrode having high adhesion and low contact resistance without causing a change in characteristics due to contamination of the exposed portions of the front and back surfaces of the thermistor body by a solution or the like at the time of electrode formation.
  • the first electrode layer including the silver layer formed so as to have an end inside the outer peripheral edge of the positive temperature coefficient thermistor element body is formed, and the first electrode layer is formed.
  • the second electrode layer made of the aluminum layer is formed so as to cover the surface and the side surfaces of the semiconductor device, it is possible to maintain good electric conductivity and completely prevent the occurrence of migration.
  • the second electrode layer is constituted by a thick film print layer containing a conductive boron compound of 5 to 60 Vo 1% and aluminum, the electrode firing step can be performed. Even if oxygen is trapped, the conductivity does not decrease, so that good electrical contact can be maintained even in a region where the second electrode directly contacts the thermistor body.
  • a contact can be formed on most of the surface of the thermistor body, so that the contact resistance can be further reduced.
  • the edges of the first and second electrode layers are covered with the third electrode layer, the occurrence of cracks and cracks in the phosphor body is further reduced.
  • the third electrode layer is formed so as to cover the edges and side surfaces except for a part of the second electrode layer but not the entire surface. As with the configuration, migration can be prevented.
  • the entire surface of the thermistor body is covered with the first electrode layer, and the second electrode layer is formed thereover.
  • the occurrence of cracks and cracks in the thermistor body is further reduced.
  • the elastic terminal uses, as a surface layer, any of nickel, silver, copper, aluminum, titanium, or an alloy thereof, which is a substance having a high melting point of an alloy with aluminum.
  • FIG. 1 is a diagram showing a thermistor according to the first embodiment of the present invention.
  • Figures 2 (a) and (b) show the manufacturing process of the same summit.
  • FIG. 3 is a diagram showing a thermistor according to the second embodiment of the present invention.
  • Fig. 4 shows a conventional thermistor (comparative example).
  • Fig. 5 shows a conventional example of a thermistor (comparative example).
  • Figure 6 shows the test equipment for the middaring test
  • Fig. 7 shows the results of a migration test performed using the device shown in Fig. 6.
  • Fig. 8 shows a test device for performing a low-temperature intermittent load test.
  • Fig. 9 is a diagram showing the results of a low-temperature intermittent load test performed using the device shown in Fig. 8.
  • Fig. 10 is a diagram showing a test device for performing a surge current test.
  • Fig. 11 shows the results of a surge current test performed using the device shown in Fig. 10.
  • Fig. 12 shows a test device for measuring the dependence of the low-temperature intermittent load test results on the terminal material.
  • Fig. 13 shows the results of a low-temperature intermittent load test performed using the device shown in Fig. 12
  • Fig. 14 shows the state of peeling by a low-temperature intermittent load test using the device shown in Fig. 12 Figure
  • Fig. 15 shows the melting point of the alloy of aluminum and nickel, silver, and tin.
  • Fig. 16 shows the relationship between the composition and melting point of the aluminum alloy tin base metal.
  • Figure 17 shows the relationship between the composition of silver-aluminum alloy and the melting point.
  • Fig. 18 shows the relationship between the composition of aluminum-nickel and the melting point.
  • Fig. 19 shows an example of the terminal structure.
  • FIG. 20 is a diagram showing the result of measuring the relationship between the element resistance and the maximum surge voltage.
  • FIG. 21 is a diagram showing the thermistor of the third embodiment of the present invention.
  • FIG. 22 is a diagram showing a thermistor according to the fourth embodiment of the present invention.
  • FIGS. 23 (a) and 23 (b) are diagrams showing a thermistor of a conventional example.
  • FIG. 1 is a diagram showing a PTC thermistor according to a first embodiment of the present invention.
  • This positive temperature coefficient thermistor is composed of a thermistor element body 1 mainly composed of barium titanate, and silver formed on the upper and lower surfaces by a printing method so that the edge is slightly intruded from the outer peripheral edge.
  • the first electrode layers 2a and 2b composed of a zinc (Ag—Zn) layer, and the silver layer (A) formed by printing to cover the first electrode layers 2a and 2b. g), and aluminum-titanium boride (A 1-) formed by a printing method so as to cover the second electrode layers 3 a and 3 b and the second electrode layers 3 a and 3 b. and a T i B 2) and the third electrode layer 4 a, 4 b made of layers.
  • the thickness of each electrode layer was about 1 °.
  • 2 (a) and 2 (b) are process diagrams showing the process of manufacturing a thermistor according to the embodiment of the present invention.
  • the powder is mixed at a specified ratio, calcined at a temperature in the range of 700 ° C to 10000 ° C, pulverized, pressed into a disk by cold pressing, and then pressurized to 130 CTC.
  • a disc-shaped thermistor body 1 having a diameter of 4.47 mm.
  • first to third electrode layers are sequentially applied to the end surface (electrode formation surface) of the thermistor body 1 by a screen printing method.
  • screen printing was first performed using an Ag-Zn paste, followed by a drying process at 18 CTC for 10 minutes, followed by screen printing using an Ag paste at 180 ° C for 10 minutes. Drying, and finally, screen printing using A 1 -TiB ⁇ paste, drying at 180 ° C for 10 minutes, and baking at 550 ° C for 10 minutes are performed.
  • a 1 — Ti B 2 paste is a mixture of aluminum powder having an average particle diameter of about 5 m and Ti B detergentceramic powder having an average particle diameter of 3 m in a mixing ratio of 7: 3. It is prepared by mixing a binder, forming a paste, and then adjusting the viscosity.
  • the thermistor obtained in this way can be used for a long time in a high-temperature and high-humidity environment because the electrode layer mainly composed of A1 that does not ionize in dew condensation water completely covers the electrode layer containing Ag. However, reliability can be maintained without silver migration. The electrical contact between the thermistor body and the electrode is good.
  • an electrode can be applied to the entire main surface of the element. Therefore, the flow of the rush current to the element becomes uniform, and it is less likely that a surge current or a voltage is applied when a voltage is applied than in the past.
  • FIG. 3 is a diagram showing a positive temperature coefficient thermistor according to a second embodiment of the present invention.
  • This positive temperature coefficient thermistor is composed of a thermistor body 1 mainly composed of titanium titanate and nickel (Ni) having a thickness of 0.3 to 2 formed by a vacuum evaporation method so as to cover the entire upper and lower surfaces thereof.
  • three electrode layers 4a and 4b The thickness of each of the second and third electrode layers was set to about 1 m.
  • the thermistor thus obtained also exhibits the above-mentioned effects, similarly to the first embodiment.
  • the same lamination as that used in the first and second embodiments of the present invention was successively laminated by a printing method such that the edge was slightly intruded from the outer peripheral edge of the phosphor body 1.
  • the electrode structure in which the first electrode layers 2a, b made of the silver-zinc layer and the second electrode layers 3a, b made of the silver layer were formed as Comparative Example 1 (FIG. 4).
  • the thermistor of Example 1 was mounted on a terminal 10 as shown in FIG. 12, and a low-temperature intermittent load test was performed to measure the terminal material.
  • the surface material of the terminal was composed of a nickel or silver plating layer
  • the electrode did not peel off after the test as shown in the table in FIG.
  • peeling occurred at the terminal contact part.
  • peeling means that peeling R occurs on an electrode surface corresponding to a contact portion with the terminal 10 as shown in FIG.
  • heat is generated due to the flow of a large current each time a voltage is applied, so there is a local temperature rise, and it is considered that aluminum and tin or solder were alloyed.
  • FIGS. 16 to 18 show the relationship between the composition and melting point of aluminum-tin alloy and the relationship between the composition and melting point of silver-aluminum alloy, respectively. And relationship.
  • the contact generates heat due to a large current every time the voltage is turned on, so the temperature locally rises and rises to about 200 ° C. Therefore, considering safety, aluminum and aluminum are required. It is desirable to use a material that does not form the following alloy.
  • the structure of the terminal is based on the whole plating method in which the entire surface of the elastic terminal or the central terminal is composed of a plating layer of nickel, copper, silver, aluminum, etc.
  • a partial plating method in which only the contact area is formed of a plating layer made of a metal as described above.
  • a terminal that is usually used and that is made of tin may be used, and at least a portion of the aluminum electrode layer that is in contact with the terminal may be further provided with a layer that is not metalized with tin.
  • this positive temperature coefficient thermistor has a thermistor body 1 mainly composed of barium titanate, and a top surface having an edge at a position slightly entering from the outer periphery.
  • a first electrode layer 2a, 2b composed of a silver-zinc (Ag-Zn) layer and a second electrode layer 3a composed of a silver layer (Ag) sequentially formed on the lower surface by a printing method.
  • 3b, and aluminum titanium boride (Al-TiB) formed by printing from the vicinity of the edge of the second electrode layer to cover the side surfaces of the first and second electrode layers.
  • the third electrode layers 4a and 4b are composed of layers. The thickness of each electrode layer is about 10 ⁇ .
  • both main surfaces of the positive temperature coefficient thermistor body can be brought into contact with the first electrode layer more. And the contact resistance is reduced.
  • the material can be reduced and the cost can be reduced.
  • this positive characteristic semiconductor is composed of a thermistor element 1 mainly composed of barium titanate and its upper surface so that the edge is slightly intruded from the outer peripheral edge. And on the lower surface, first electrode layers 2a and 2b made of a silver-zinc (Ag-Zn) layer formed by a printing method, and a printing method formed so as to cover the first electrode layer.
  • each electrode layer was about 10 ⁇ m.
  • the aluminum layer is not limited to pure aluminum but refers to a layer containing aluminum as a main component.

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Thermistors And Varistors (AREA)

Abstract

Thermistor de haute fiabilité à coefficient positif de température n'étant le siège d'aucune migration d'argent même dans des conditions de température et d'humidité élevées. L'invention se caractérise principalement par le fait que les premières couches des électrodes (2a, 2b, 3a et 3b), dont une d'argent, formées sur les deux surfaces principales du corps (1) du thermistor sont disposées de manière à ce que leurs extrémités se trouvent à l'intérieur du périmètre extérieur du corps (1) nu, et que les secondes couches (4a et 4b) des électrodes soient en aluminium et recouvrent les surfaces et les faces latérales des premières couches des électrodes.
PCT/JP1995/000334 1994-03-04 1995-03-02 Thermistor a coefficient positif de temperature WO1995024046A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP95910727A EP0749132A4 (fr) 1994-03-04 1995-03-02 Thermistor a coefficient positif de temperature

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP3490394 1994-03-04
JP6/34903 1994-03-04

Publications (1)

Publication Number Publication Date
WO1995024046A1 true WO1995024046A1 (fr) 1995-09-08

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0724272A1 (fr) * 1995-01-26 1996-07-31 Murata Manufacturing Co., Ltd. Dispositif à thermistance

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS52120337U (fr) * 1976-03-10 1977-09-12
JPS55118601A (en) * 1979-03-06 1980-09-11 Tdk Electronics Co Ltd Porcelain semiconductor element
JPH05275204A (ja) * 1992-03-25 1993-10-22 Murata Mfg Co Ltd 正特性サーミスタ装置

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS52120337U (fr) * 1976-03-10 1977-09-12
JPS55118601A (en) * 1979-03-06 1980-09-11 Tdk Electronics Co Ltd Porcelain semiconductor element
JPH05275204A (ja) * 1992-03-25 1993-10-22 Murata Mfg Co Ltd 正特性サーミスタ装置

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP0749132A4 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0724272A1 (fr) * 1995-01-26 1996-07-31 Murata Manufacturing Co., Ltd. Dispositif à thermistance
US6177857B1 (en) 1995-01-26 2001-01-23 Murata Manufacturing Co., Ltd. Thermistor device

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