JP2013197002A - Circuit protection element - Google Patents

Abstract

An object of the present invention is to provide a circuit protection element that can prevent an element portion from being deteriorated by a steady-state current.
A circuit protection element according to the present invention is formed so as to bridge a pair of upper surface electrodes provided on an insulating substrate, and is electrically connected to the pair of upper surface electrodes. A pair of insulating layers 15 provided so as to cover the element part 13 and a fusing part 16 provided in the element part 13, and the element part 13 is connected to the pair of upper surface electrodes 12. The first element portion 13a and the second element portion 13b provided between the pair of first element portions 13a, and the first element portion 13a is formed of a material having a negative resistance temperature coefficient. In addition, the second element portion 13b is formed of a material having a plus resistance temperature coefficient, and the fusing portion 16 is further formed in the second element portion 13b.
[Selection] Figure 1

Description

  The present invention relates to a circuit protection element that melts and protects various electronic devices when an overcurrent flows.

  As shown in FIGS. 4 and 5, this type of conventional circuit protection element includes a rectangular insulating substrate 1, a pair of upper surface electrodes 2 provided at both ends of the upper surface of the insulating substrate 1, and the insulating material. An element portion 3 made of a metal such as Cu and electrically connected to the pair of upper surface electrodes 2 on the upper surface of the substrate 1, an insulating layer 4 provided so as to cover the element portion 3, and the insulating substrate 1 And a pair of trimming grooves for forming a fusing part by cutting with a laser from the side edges of the element part 3 facing each other toward the center of the element part 3. 6 and a fusing part 7 that melts and cuts off the current when an overcurrent is applied is provided in a region surrounded by the pair of fusing part forming trimming grooves 6.

  As prior art document information relating to the invention of this application, for example, Patent Document 1 is known.

JP 2000-331590 A

  In the conventional circuit protection element described above, the element portion 3 is made of metal, and the metal generally has a positive resistance temperature coefficient (TCR) and a large value. Due to the self-heating, the resistance value of the element part 3 is increased, and the element part 3 further generates heat. As a result, since the increase in the resistance value of the element unit 3 is accelerated, the temperature of the element unit 3 is increased even in a steady-state current, thereby causing a problem that the element unit 3 is deteriorated. .

  And when the element part 3 deteriorates, when the electric current of a steady state continues being applied, malfunctions, such as fusing in a comparatively short time, may arise.

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide a circuit protection element capable of preventing the element portion from being deteriorated by a steady-state current.

  In order to achieve the above object, the present invention has the following configuration.

  According to a first aspect of the present invention, there is provided a rectangular insulating substrate, an element portion provided on the insulating substrate, an insulating layer provided so as to cover the element portion, and the element portion. A fusing portion, and the element portion is constituted by a pair of first element portions and a second element portion provided between the pair of first element portions, and the first element portion According to this structure, the second element portion is formed of a material having a positive resistance temperature coefficient, and the fusing portion is formed in the second element portion. For example, the temperature coefficient of resistance of the entire element can be brought close to zero, so even if the ambient temperature is high or the element is heated when a steady-state current is applied, the element is heated. The resistance value of the element part hardly changes, and this can suppress the temperature rise of the element part with a steady-state current, so that the element part can be prevented from deteriorating, and an overcurrent is applied. Since the fusing part that generates heat is formed in the second element part made of a material having a positive resistance temperature coefficient, the resistance value of the fusing part increases due to the heat of the fusing part that generates heat due to overcurrent. As a result, the fusing part further generates heat, and the resistance value increases, so that the temperature of the fusing part rises at an accelerated speed, so that the effect of improving the quick cutting property can be obtained.

  According to a second aspect of the present invention, there is provided a rectangular insulating substrate, an element portion provided on the insulating substrate, an insulating layer provided so as to cover the element portion, and the element portion. A fusing portion, and the element portion is constituted by a pair of first element portions and a second element portion provided between the pair of first element portions, and the first element portion The second element portion is formed of a material having a positive resistance temperature coefficient, the fusing portion is formed in the second element portion, and the first element portion is formed of a material having a resistance temperature coefficient of substantially zero. A resistance value adjusting trimming groove is formed in the element portion by laser irradiation. According to this configuration, the resistance value adjusting trimming groove is formed of a material having a resistance temperature coefficient of zero. Therefore, even if heat from laser irradiation is applied to the element part during the formation of the trimming groove for adjusting the resistance value, the resistance value of the element part hardly fluctuates. The effect that it can be implemented with high accuracy is obtained.

  As described above, in the circuit protection element of the present invention, the first element portion is formed of a material having a negative resistance temperature coefficient and the second element portion is formed of a material having a positive resistance temperature coefficient. The resistance temperature coefficient of the entire part can be brought close to zero, so that even if the ambient temperature rises or the element part generates heat when a steady-state current is applied, the resistance value of the element part hardly changes. Therefore, it is possible to suppress the temperature rise of the element part due to the steady-state current, thereby preventing the element part from deteriorating, and further, the fusing part that generates heat when an overcurrent is applied is provided in the second part. Since it is formed in the element part, the resistance value of the fusing part becomes higher due to the heat of the fusing part that has generated heat due to overcurrent. The temperature of the fusing part and so is accelerated rate increase that is higher, in which exhibits an excellent effect that a fast-acting property is improved.

1 is a partially cutaway top view of a circuit protection element according to an embodiment of the present invention. AA line sectional view of FIG. Another cutaway top view of another example of the circuit protection element Partial cutaway top view of a conventional circuit protection element BB sectional view of FIG.

  Hereinafter, a circuit protection element according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a partially cutaway top view of a circuit protection element according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line AA of FIG.

  As shown in FIGS. 1 and 2, the circuit protection element according to the embodiment of the present invention includes a rectangular insulating substrate 11, a pair of upper surface electrodes 12 provided on the insulating substrate 11, and the pair of upper surfaces. An element portion 13 formed so as to bridge the electrode 12 and electrically connected to the pair of upper surface electrodes 12, a base layer 14 provided between the element portion 13 and the insulating substrate 11, and an element The insulating layer 15 provided so as to cover the portion 13 and the fusing portion 16 provided in the element portion 13 are provided, and the element portion 13 is connected to the pair of upper surface electrodes 12. It comprises a part 13a and a second element part 13b provided between the pair of first element parts 13a, and a fusing part 16 is formed in the second element part 13b. In FIG. 1, the base layer 14 and the insulating layer 15 are omitted.

  Further, the first element portion 13a is formed of a material having a negative resistance temperature coefficient, and the second element portion 13b is formed of a material having a positive resistance temperature coefficient.

In the above configuration, the insulating substrate 11 has a rectangular shape (rectangular when viewed from above) and is made of alumina containing 55 to 96% Al ₂ O ₃ . The pair of upper surface electrodes 12 are formed by printing Ag or the like on both ends of the insulating substrate 11 on the upper surface of the insulating substrate 11.

  The element portion 13 is provided on the upper surface of the base layer 14 and the pair of upper surface electrodes 12 so as to cover the insulating substrate 11.

  Furthermore, the element portion 13 includes a pair of first element portions 13a directly connected to the pair of upper surface electrodes 12, and a second element portion 13b provided between the pair of first element portions 13a. The first element portion 13a, the second element portion 13b, and the first element portion 13a are configured in series in this order.

  The first element portion 13a is formed of a CuNi alloy having a negative temperature coefficient of resistance containing 65% to 45% (preferably 55%) of Cu and 35% to 55% (preferably 45%) of Ni. The second element portion 13b is made of a metal such as Cu, Al, or Ag having a positive resistance temperature coefficient. Furthermore, it is preferable that the resistance temperature coefficient of the entire element portion 13 is substantially zero. In order to make the resistance temperature coefficient of the entire element portion 13 substantially zero, the ratio of Cu and Ni in the first element portion 13a, second The material used for the element portion 13b and the size and thickness of the first and second element portions 13a and 13b are defined.

  Then, as shown in FIG. 2, a thin film layer 13c is formed by sputtering on the lower surfaces of the first and second element portions 13a and 13b, and then the first and second elements are plated by using the thin film layer 13c as a plating nucleus. The element portions 13a and 13b are formed. The first and second element portions 13a and 13b may be formed only by sputtering.

  Furthermore, at the center of the second element portion 13b, a pair of fusing portion forming trimming grooves 16a and 16b are formed by a laser from the side of the second element portion 13b facing each other. The region surrounded by the pair of fusing portion forming trimming grooves 16a and 16b is formed in an overcurrent direction toward the center of the second element portion 13b, that is, substantially perpendicular to the side of the second element portion 13b. It forms a melted part 16 that melts and breaks when is applied. The fusing part 16 may be formed by patterning instead of the fusing part forming trimming grooves 16a and 16b.

  The underlayer 14 is provided at the center of the upper surface of the insulating substrate 11 and between the element portion 13 and the insulating substrate 11 positioned between the pair of upper surface electrodes 12. Further, the base layer 14 is composed of a mixture of a silicon resin and a filler, and since this silicon resin has low thermal conductivity, the heat of the element portion 13 is insulated by the base layer 14 by an insulating substrate. 11 can be prevented from diffusing.

  The underlying layer 14 is formed not only on the central portion of the insulating substrate 11 but also on almost the entire upper surface of the insulating substrate 11, and a pair of upper surface electrodes 12 are formed on both ends of the underlying layer 14. May be.

  The insulating layer 15 is provided so as to cover at least a part of the element portion 13, and the insulating layer 15 is a first insulating layer made of a resin such as silicon and covering the fusing portion 16. 15a and a second insulating layer 15b made of a resin such as epoxy provided on the upper surface of the first insulating layer 15a.

  End electrodes 17 are formed on both ends of the insulating substrate 11 by plating a silver material so as to overlap a part of the element portion 13. A plating film (not shown) made of nickel and tin is formed.

  Next, the manufacturing method of the circuit protection element in one embodiment of the present invention is explained.

1 and 2, first, silver paste or silver as a main component is formed on both ends of the insulating substrate 11 on the upper surface of the rectangular insulating substrate 11 made of alumina containing 55 to 96% Al ₂ O _3. A pair of upper surface electrodes 12 is formed by printing and firing a silver-palladium alloy conductor paste.

  Next, a paste made of a mixture of a filler and a silicon resin and an organic solvent is printed on the central portion of the insulating substrate 11, and then cured at about 150 ° C. to 200 ° C. to evaporate the organic solvent. Form.

  Next, the element portion 13 is formed on the upper surface of the base layer 14 and the pair of upper surface electrodes 12 so as to cover the insulating substrate 11. The element portion 13 is configured so as to be electrically connected to the pair of upper surface electrodes 12 by bridging between the pair of upper surface electrodes 12.

  And this element part 13 provides the thin film layer 13c by sputter | spatterring Ti, Cu or Cr, CuNi in order first. Thereafter, the thin film layer 13c is used as a plating nucleus, and predetermined CuNi is electrolessly plated or electroplated so as to be directly connected to the pair of upper surface electrodes 12, thereby forming a pair of first element portions 13a. Thereafter, the second element portion 13b is formed by electroless plating or electrolytic plating of a metal such as Cu, Al, or Ag between the pair of first element portions 13a using the thin film layer 13c as a plating nucleus. In addition, after forming the 2nd element part 13b, you may form a pair of 1st element part 13a.

  Next, a pair of fusing is performed by cutting the two portions of the center portion of the second element portion 13b with a laser from the side edges of the second element portion 13b facing each other toward the center direction of the second element portion 13b. The part forming trimming grooves 16a and 16b are formed, and a fusing part 16 that is melted and disconnected when an overcurrent is applied is provided in a region surrounded by the pair of fusing part forming trimming grooves 16a and 16b. .

  Next, the first insulating layer 15a is provided by forming a resin such as silicon so as to cover at least the fusing portion 16. Thereafter, a resin such as epoxy is formed on the upper surface of the first insulating layer 15a to provide a second insulating layer 15b, thereby forming the insulating layer 15 having two layers.

  Next, the end face electrode 17 is formed by plating silver so as to overlap a part of the element part 13 at both ends of the insulating substrate 11.

  Finally, a plated film (not shown) having a two-layer structure of nickel and tin is formed on the end face electrode 17 to manufacture the circuit protection element in one embodiment of the present invention.

  In the above-described embodiment of the present invention, the element portion 13 is composed of the first element portion 13a and the second element portion 13b, and the first element portion 13a is formed of a material having a negative resistance temperature coefficient. In addition, since the second element portion 13b is formed of a material having a positive resistance temperature coefficient, the resistance temperature coefficient of the entire element portion 13 can be brought close to zero, thereby increasing the ambient temperature or increasing the steady state. Even when the element part 13 generates heat due to the current being applied, the resistance value of the element part 13 hardly changes, so that the temperature of the element part 13 does not increase at an accelerated rate. The effect that it can prevent that the element part 13 deteriorates with an electric current is acquired.

  Further, since the fusing part 16 that generates heat when an overcurrent is applied is formed in the second element part 13b having a positive resistance temperature coefficient, the resistance of the fusing part 16 is generated by the heat of the fusing part 16 that generates heat due to overcurrent. Since the value becomes higher and the fusing part 16 further generates heat and the resistance value becomes higher, the temperature of the fusing part 16 rises at an accelerated rate, so that the quick cutting property is improved.

  That is, when a constant low current is applied, the entire element portion 13 generates heat. Therefore, if the resistance temperature coefficient is set to zero as the total element portion 13, the ambient temperature increases or the element portion 13 self-heats. However, the resistance value does not change, and as a result, the temperature rise of the element portion 13 is suppressed, so that the element portion 13 can be prevented from being deteriorated by a steady-state current. On the other hand, when an overcurrent is applied, the fusing part 16 generates heat. Therefore, if only the fusing part 16 has a positive resistance temperature coefficient, the resistance value of the fusing part 16 itself increases due to self-heating of the fusing part 16, As a result, the fusing part 16 further generates heat, and the temperature of the fusing part 16 increases at an accelerated rate as a result of the heat generation further increasing the resistance value of the fusing part 16 itself. As a result, the fusing part 16 is blown quickly. , Quick disconnection is improved. Therefore, a circuit protection element that does not melt even when a steady-state current is applied but that melts quickly when an overcurrent is applied is obtained.

  In the circuit protection element according to the embodiment of the present invention, the first element portion 13a is formed of a material having a negative resistance temperature coefficient. However, the resistance temperature coefficient of the first element portion 13a is The first element portion 13a may be provided with a trimming groove 16c for adjusting a resistance value, as shown in FIG.

  That is, when the trimming groove 16c for adjusting the resistance value is formed by laser irradiation in order to improve the resistance value accuracy in the first element portion 13a, the resistance temperature coefficient of the first element portion 13a is negative or positive. The resistance value of the first element portion 13a varies each time due to heat generated by laser irradiation, and the resistance value is corrected based on the varied resistance value. However, the accuracy of the final resistance value is deteriorated. If the temperature coefficient of resistance of the first element portion 13a is made substantially zero, the resistance value of the element portion 13 hardly fluctuates due to the heat generated by laser irradiation, so that the resistance value can be adjusted with high accuracy.

  Further, if the resistance temperature coefficient of the first element portion 13a is made substantially zero, the resistance temperature coefficient of the entire element portion 13 becomes positive, but the value can be kept relatively low. It is possible to prevent the part from deteriorating.

In order to make the resistance temperature coefficient of the first element portion 13a substantially zero (± 0 × 10 ⁶ / ° C.), a CuNi alloy with 68% Cu and 32% Ni may be used.

  Further, the pair of upper surface electrodes 12 may be omitted, and in this case, the pair of first element portions 13 a are directly connected to the end surface electrodes 17.

  The circuit protection element according to the present invention has an effect of preventing the element portion from being deteriorated by a steady-state current, and in particular, circuit protection that melts and protects various electronic devices when an overcurrent flows. This is useful in devices and the like.

DESCRIPTION OF SYMBOLS 11 Insulating substrate 13 Element part 13a 1st element part 13b 2nd element part 15 Insulating layer 16 Fusing part 16c Trimming groove for resistance value adjustment

Claims (2)

A rectangular insulating substrate, an element portion provided on the insulating substrate, an insulating layer provided so as to cover the element portion, and a fusing portion provided on the element portion, the element portion, It comprises a pair of first element parts and a second element part provided between the pair of first element parts, and the first element part is made of a material having a negative resistance temperature coefficient and The circuit protection element which formed the 2nd element part with the material with a plus temperature coefficient of resistance, and also formed the fusing part in the 2nd element part. A rectangular insulating substrate, an element portion provided on the insulating substrate, an insulating layer provided so as to cover the element portion, and a fusing portion provided on the element portion, the element portion, A pair of first element portions and a second element portion provided between the pair of first element portions are formed, and the first element portion is formed of a material having a resistance temperature coefficient of substantially zero. The second element portion is formed of a material having a positive resistance temperature coefficient, the fusing portion is formed in the second element portion, and a trimming groove for adjusting a resistance value is formed in the first element portion by a laser. Circuit protection element formed by irradiation.

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