JPH0641316Y2 - Thermal fuse resistor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a thermal fuse resistor used in a maintenance circuit of electronic equipment.

(B) Conventional technology Generally, so-called fuse resistors or thermal fuses are used to secure safety against overcurrent or temperature rise of electronic equipment, but the following methods are generally adopted for these. ing. That is, one of them is a fuse resistor, and when the current value flowing in the fuse resistor forming the circuit exceeds a predetermined value, the fuse resistor overheats and the temperature rises and within a predetermined time. This is a method of cutting off the current by burning. One is a method in which when a temperature inside the device exceeds a predetermined temperature, a temperature fuse forming a circuit is melted and melted within a predetermined time to cut off an electric current. Further, there is a method in which the above two are combined and the temperature rise due to heat generation of the resistor is transmitted to the thermal fuse to melt the thermal fuse.

(C) Problems to be solved by the invention However, in all of the above, there are large variations in the starting time and duration of current interruption due to some differences in shape, heat transfer distance, heat capacity, etc. Not only is it extremely difficult to operate, but its shape is too large, which is a major obstacle to downsizing of equipment. For this reason, there was great concern about accurate and precise safety control.

(D) Means for solving the problems This invention eliminates these drawbacks, and a metal film resistor is formed by vapor deposition on a small ceramic substrate excellent in heat conduction, and one end of which is temperature-sensitive fusion. A thermal fuse resistance circuit is formed by connecting it close to one end of a metal piece, and a metal plate with excellent heat conduction is previously soldered to the entire back surface of the board to provide a heat capacity as a mounting surface for a radiator. It is a small thermal fuse resistor with extremely small and large heat dissipation. That is, when the equipment is operating, the ambient temperature is the sum of the ambient temperature and the temperature rise of the metal film resistance, or when the temperature rise due to the heat generation of the metal film resistance accompanying the increase of the current reaches a predetermined temperature. Then, the temperature-sensitive fusible metal piece melts, and due to its surface tension, it agglomerates and spheres to melt and cut off the electric current. Moreover, since the temperature rise of the metal film resistor is largely suppressed by mounting it on the radiator by the heat radiation from the back surface of the small substrate, the power of the metal film resistor can be used at a power much higher than the rated power at room temperature. .
Explaining this with reference to the drawing, 1 is an extremely thin small ceramic substrate with good heat conduction (12.5 mm × 14.5 mm ×
(Thickness 0.635 mm or less) Metal film resistor 2 on a part of this surface
Is vapor-deposited and formed, and the thermally and electrically conductive metal thin film 3 previously vapor-deposited and formed is connected to one end thereof, and the lead wire 6 is soldered to the other end of the metal film resistor. Reference numeral 4 denotes a temperature-sensitive fusible metal piece, one end of which is connected to the heat and electric conductive metal thin film 3, and the other end of the temperature-sensitive fusible metal piece 4 is connected to the vapor-deposited and formed electric conductive metal thin film 5. A lead wire 7 is soldered to the other end of the electrically conductive metal thin film 5. A thermal conductive metal thin film 10 is previously vapor-deposited and formed on the entire back surface of the substrate 1 having the thermal fuse resistance circuit formed on the same substrate in this manner, and the thermal conductive metal plate 9 is spread over the entire surface. Solder under pressure.
Since the surface of the metal plate 9 of the substrate thus configured is attached to the radiator to radiate heat, it can be made compact and can be used with a large amount of power, and extremely accurate and precise fusing operation can be performed.

(E) Action The temperature fuse resistor according to the present invention, when connected in the maintenance circuit of the equipment, when the ambient temperature exceeds the predetermined temperature, the sum of the ambient temperature and the temperature rise due to the heat generation of the metal film resistor 2 When the temperature exceeds the predetermined temperature or when the temperature rise due to heat generation of the metal film resistor 2 exceeds the predetermined temperature, the temperature-sensitive fusible metal piece 4 melts and cuts off the current. That is, the temperature rise due to heat generation of the metal film resistor 2 is transmitted to the temperature-sensitive fusible metal piece 4 through the heat conductive metal thin film 3, but the heat transfer between the metal film resistance and the temperature-sensitive fusible metal piece 4 is conducted. Since the path is extremely short and the heat resistance is small, there is no heat loss, so there is no temperature drop due to heat transfer from the metal film resistor 2, and when the metal film resistor 2 reaches a predetermined temperature, the temperature can be quickly sensed and fused. The metal piece 4 melts and melts. Therefore, the fusing operation is accurate,
Done quickly. Also, if this temperature fuse resistor is attached to a radiator and used, the metal plate 9 press-soldered on the back surface of the substrate 1 directly radiates heat and suppresses the temperature rise. It can be used with much higher power. As an example, a temperature fuse resistor that melts at a resistance value of 100Ω, a rated power of 1.8 W, and a temperature of 117 ° C. is obtained. (Rated power at room temperature: 0.25W) (f) Effect of the device The thermal fuse resistor according to the present invention can be cut into various types of fusing by presetting the resistance value, current value, temperature, and shape and size of the radiator. It is characterized in that the current value and the fusing temperature can be obtained. Therefore, it can be inserted into the maintenance circuit of electronic equipment, and it can keep a large power with a small size.
In addition, since the variation is small and the fusing operation can be performed accurately and precisely, the safety control of the equipment can be secured.

[Brief description of drawings]

FIG. 1 is a front view of the thermal fuse resistor, and FIG. 2 is a side view thereof. 1 ... Ceramic substrate, 2 ... Metal film resistance, 3 ... Heat and electric conductive metal thin film, 4 ...
...... Electrically conductive metal thin film, 6 ...... Lead wire, 7 ...... Lead wire, 8 ...... Solder, 9 ...... Heat conductive metal plate, 10 ...... Heat conductive metal thin film

Claims (1)

[Scope of utility model registration request] 1. A ceramic small substrate (1) having excellent thermal conductivity, wherein a metal film resistor (2) is formed on a part of one side of the substrate by vapor deposition, and one end of a temperature-sensitive fusible metal piece (4) is formed at one end thereof. The thermal fuse resistance circuit on the same substrate, which is formed by closely connecting the two, and a metal thin film (10) excellent in heat conduction is vapor-deposited over the entire back surface of the small substrate (1). ) A heat radiating mechanism formed by pressing and soldering a heat-conductive metal plate (9) covering the upper part of the above, and a miniature temperature fuse resistor.