JPH06224011A - Fuse resistor - Google Patents

Abstract

PURPOSE:To provide a fuse resistor having fuse characteristics in less dispersion and short fusing time. CONSTITUTION:A resistor is formed on an insulating substrate, a resisting film 2 with electrode parts formed on both ends is partly cut off to provide electrically insulating part 5 so that a band type conductive metallic film 6 may be formed on the insulating part 5 by sputtering step, etc., to be shortcircuited. Next, the shortcircuited metallic film 6 comprising Pb, Sn, Zn, Al, Cu, Fe and the alloys thereof is heat-treated in vaccum or an inert gas atmosphere to enhance the reliability upon the metallic film 6. At this time, the resistance value can be adjusted with high precision by cutting off the resistance film 2 excluding the shortcircuited part. Through these procedures, the deterioration in the title fuse resistor can be avoided even in severe environment of applications by sealing the fuse resistor in vacuum or the inert gas atmosphere.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuse resistor mounted on an electronic circuit board, which serves as an excellent resistor in a steady state and has an abnormally large current. In contrast, it melts and cuts off instantly. [0002] A conventional fuse resistor is a method of providing a fuse function in which a resistor is melted and cut by Joule heat generated when a large current flows and a fuse action connected in series to the resistor. It can be roughly divided into those that melt the body. In the former case, a method is generally used in which Sn or Pb is mixed with a paint in the resistance film and the heat generated by a large current is used to precipitate the metal to rapidly reduce the resistance value and melt the material.
In the latter case, a low melting point metal is connected in series to the resistor and a large current is used to melt the part, and various structures have been devised. [0003] Problems to be Solved by the Invention [0005] Sn or Pb is used as a resistance film.
In the method of applying paint mixed with the above, and utilizing the heat generated by a large current to precipitate the metal and rapidly reduce the resistance value to melt the fuse, it is difficult to suppress the fluctuation of the time required for melting, In this case, there is a risk that the resistor itself will become hot and will have a bad thermal effect on other circuit parts.
Further, it is difficult to reduce the size and weight of a metal by connecting a metal having a low melting point in series and melting the portion with a large current, and the processing process is likely to be complicated, which causes a large obstacle in terms of cost. Further, the conventional fuse resistor has a problem that it is difficult to control the resistance value with high accuracy and the heat resistance is poor. According to the present invention, a resistive element is formed on an insulating substrate, and the resistive film of a resistive element having electrode portions formed on both ends thereof is partially cut off to electrically cut the resistive element. It is characterized in that an insulated portion is provided, and then a conductive metal film is deposited on the insulating portion in a band shape by a method such as sputtering to short-circuit. The metal film to be short-circuited is Pb, Sn, Zn, A
1, Cu, Fe and their alloys can be used. By performing the heat treatment in vacuum or in an inert gas, the reliability of the short-circuited metal film can be improved. Further, by cutting the resistance film excluding the short-circuited portion, the resistance value can be adjusted with high accuracy. Furthermore,
By carrying out vacuum sealing or inert gas sealing,
It is possible to prevent functional deterioration even in a severe use environment. [Production] The product of the present invention has the following actions. 1 The fusing performance is controlled by the type of metal to be short-circuited, the film thickness and the film deposition area. 2 Since the number of heat generation points during fusing is very small, the resistor itself does not reach a high temperature. 3 Compactness and weight reduction can be realized by utilizing the structure of the conventional resistor. 4 The resistance value is controlled with high accuracy by cutting off the resistive film part excluding the short-circuited part. 5 After short-circuiting, place the element in vacuum or in an inert gas for 15
Heat resistance is improved by heat treatment at 0 ° C to 200 ° C. 6. Vacuum fuse or inert gas seal the fuse resistor to prevent oxidation. [Embodiment 1] An embodiment according to the contents described in the claims of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view showing a fuse resistor of the embodiment. After depositing a resistance thin film 2 such as a nichrome alloy on a substrate 1 made of an insulating material whose main component is alumina 70%,
The cap 3 and the lead wire 4 are connected. An insulating groove 5 having a width of 200 μ is provided at one location of the resistor, and an Al film 6 is deposited on the short-circuited portion by sputtering to short-circuit. [Embodiment 2] FIG. 2 shows that after a resistance thin film 2 such as a nichrome alloy is deposited on a substrate 1 made of an insulating material whose main component is alumina 70%, a cap 3 and a lead wire 4 are attached. Connecting. Insulation groove 5 with a width of 200μ at two points on the resistor
(A) and 5 (b) are provided, and the Al film 6 is deposited on the short-circuited portion by sputtering and short-circuited. [Embodiment 3] FIG. 3 is an explanatory view showing a fuse resistor of one embodiment. After a resistance thin film 2 such as a nichrome alloy is deposited on a substrate 1 made of an insulating material whose main component is alumina 70%, a cap 3 and a lead wire 4 are connected. An insulating groove 5 having a width of 200 μ is provided at one location of the resistor, and an Al film 6 is deposited on the short-circuited portion by sputtering to short-circuit. Further, a cut groove 7 was formed in the resistance film portion to finely adjust the resistance value. [Embodiment 4] FIG. 4 is an explanatory view showing a fuse resistor of the embodiment. After a resistance thin film 2 such as a nichrome alloy is deposited on a substrate 1 made of an insulating material whose main component is alumina 70%, a cap 3 and a lead wire 4 are connected. An insulating groove 5 having a width of 200 μ was provided at one location of the resistor, and an Al film 6 was deposited on the short-circuited portion by sputtering to short-circuit and sealed with a glass tube 8 in vacuum. [Embodiment 5] FIG. 5 shows a sample obtained by heating the fuse resistor of Embodiment 3 at 200 ° C. for 4 hours in vacuum.
The results of the standing test in a constant temperature and humidity chamber of 50 ° C. are shown.
In FIG. 5, the case without heat treatment is indicated by A, and the case with heat treatment is indicated by B. As shown in FIG. 5, the heat treatment makes it possible to manufacture a highly stable fuse resistor. [Embodiment 6] FIG. 6 shows the results of a standing test conducted in a constant temperature and humidity chamber at 150 ° C. using a fuse resistor of Example 3 sealed in a vacuum as a sample. In FIG. 6, the case without vacuum sealing is shown with A, and the case with heat treatment is shown with C. As shown in FIG. 6, a highly stable fuse resistor can be manufactured by vacuum sealing. As described above, the product of the present invention has the effect of solving various problems of the prior art. 1 Since the fusing performance of the invention product is controlled by the kind of the metal to be short-circuited, the film thickness and the film deposition area, it is possible to manufacture a fuse resistor having a short fusing time and a small variation in the time required for the fusing. As can be seen from Table 1, even if the characteristic 1 is applied, that is, the electric power of 9 times the rated electric power is applied, the fusing occurs in 30 seconds or less. Further, by increasing the number of insulating grooves, variations in fusing time can be further reduced. (2) Since the heat generation point at the time of fusing is a very small area and the fusing time is short, the resistor itself does not reach a high temperature, and there is no risk of adversely affecting other circuit components thermally. Surface temperature during melting is 30
It was below 0 ° C. 3 Compactness and weight reduction can be realized by utilizing the structure of the conventional resistor. Therefore, it can be manufactured at low cost. 4. The resistance value can be easily controlled with high accuracy by cutting off the resistive film portion excluding the short-circuited portion. 5 After short-circuiting, place the element in vacuum or in an inert gas for 15
Heat treatment at 0 ° C to 200 ° C can improve heat resistance. 6. If the fuse resistor is vacuum-sealed or sealed with an inert gas, the fuse resistor has excellent environmental resistance. [Table 1] Fusing characteristic 1: Fusing time (second) when applying 9 times the rated power Fusing characteristic 1: Fusing time (second) when applying 12 times the rated power Fusing characteristic 1: 16 times the rated power was applied Case fusing time (seconds)

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1, FIG. 2 and FIG. 3 are front views showing a structure of a fuse resistor in an embodiment of the present invention. FIG. 4 is a sectional view showing a structure of a fuse resistor according to an embodiment of the present invention. FIG. 5 and FIG. 6 are diagrams showing the results of a standing test at 150 ° C. of a fuse resistor manufactured according to an example of the present invention. [Explanation of reference numerals] 1 substrate, 2 thin film for resistance 3 cap 4 lead wire 5 5a, 5b insulating groove 6 metal thin film 7 cut groove 8 glass tube

Claims (1)

Claim: What is claimed is: 1. A resistive element having a resistive element formed on an insulating substrate and electrode portions formed on both ends of the resistive element. A fuse resistor in which Pb and Al are short-circuited with a conductive metal film. 2. A fuse resistor in which two or more electrically insulated portions are provided on the surface of the resistance element, and then the insulating portion is short-circuited with a conductive metal film such as Pb or Al. Item 3. Regarding the item 1, the resistance element having a resistor film formed on a cylindrical insulating substrate and having electrode portions formed on both ends thereof has a circumferentially electrically insulated portion of 200 μ or less.
A fuse resistor provided at a location and then the insulating portion is short-circuited with a conductive metal film such as Pb or Al. Item 4. Regarding the item 2, the resistance element having a resistor film formed on a cylindrical insulating substrate and having electrode portions formed on both ends thereof is provided with two circumferentially electrically insulated portions of 200 μ or less.
A fuse resistor in which more than one place is provided, and then the insulating part is short-circuited with a conductive metal film such as Pb or Al. Item 5. The fuse resistor according to items 3 and 4, wherein the resistance film portion is spirally cut after a short circuit and the resistance value is finely adjusted. [Claim 6] Concerning claims 3, 4 and 5, 150 ° C
Fuse resistor heat-treated in a vacuum atmosphere in the temperature range from 1 to 200 ° C. [Claim item 7] Regarding claim items 3, 4, and 5, 150 ° C.
Fuse resistor heat-treated in the inert gas atmosphere in the temperature range from 1 to 200 ° C. [Claim item 8] Regarding claim items 3, 4 and 5, 150 ° C.
Fuse resistor vacuum sealed in the temperature range from 1 to 200 ° C. [Claim 9] Regarding Claims 3, 4 and 5, 150 ° C
Fuse resistor sealed with an inert gas in the temperature range from 1 to 200 ° C.