JP2001217101A - Resistor for detecting current - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resistor for detecting a current for improving insulating properties, while being able to increase power capacity. SOLUTION: A resistor 12 is fixed into a box body-shaped cover member 15, in which an insulating one surface is opened, by using a sealing material 16, and electrode sections 12a, 12b for the resistor are extracted from the sealing material 16. The sealing material 16 is made of cement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current detecting resistor, and more particularly to a low-resistance large-current resistor suitable for detecting a current value of a power supply device or the like.

[0002]

2. Description of the Related Art In various electronic devices, a power supply circuit is mounted on a printed circuit board, and a current detection resistor called a shunt resistor is used to detect a current value supplied from the power supply circuit. There are many. As such a current detecting resistor, a resistor having a low resistance of the order of mΩ and a large power type is generally used.

As an example of such a resistor, a resistor as shown in FIG. 5 is known. This is obtained by processing a copper-nickel-based alloy or nickel-chromium-based alloy wire having a diameter of about several mm into a shape as shown in the figure to obtain a resistor 11 having a low resistance and a large current capacity of about 10 mΩ, for example. It is. The end 11a of this resistor is inserted into the hole of the printed circuit board and soldered, so that it is arranged in series on the current path, and the current value can be detected from the voltage generated at both ends.

A shunt resistor having a shape shown in FIG. 6 is also known. This is formed, for example, by bending a plate material of a copper-nickel-based alloy or a nickel-chromium-based alloy, but since it has a planar terminal portion 12a, surface mounting becomes possible. Furthermore, a film resistor type resistor shown in FIG. 7 is also used as a shunt resistor.

[0005]

However, since the above-mentioned shunt resistor is formed by using a bare metal wire or a bare plate, there is a case where a problem arises because the charged portion is exposed at the time of mounting. . In addition, with the progress of high-density mounting of components, a shunt resistor that is as small as possible and has a large current capacity is required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a current detecting resistor capable of improving the insulation and increasing the power capacity.

[0007]

According to the first aspect of the present invention, there is provided a box-shaped cover member having an open insulating surface.
A resistor for current detection, wherein a resistor is fixed using an encapsulating material, and an electrode portion of the resistor is taken out of the encapsulating material.

[0008] Thus, since the resistor is fixed in the insulating cover using the encapsulating material, the insulating property is improved. Then, the heat dissipated from the resistor is transferred to the cover member via the encapsulating material, and since these have good heat conductivity and a large heat dissipation area, the power capacity of the resistor is improved.

The invention according to claim 2 is characterized in that the encapsulating material is cement.

As a result, the cement exhibits good insulating properties and good thermal conductivity, so that it can be suitably used as an encapsulant. Further, the handling in the manufacturing stage is easy, and the current detecting resistor of the present invention can be manufactured at a relatively low cost.

The invention according to claim 3 is characterized in that the tip of the electrode portion is bent along the side end surface of the box-shaped cover member.

[0012] Accordingly, since the solder adheres to the bent portion at the tip of the electrode exposed to the outside during surface mounting, the solder adhesion as a resistor can be improved, and the solder adhesion can be easily confirmed visually. be able to.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a current detecting resistor according to a first embodiment of the present invention. In this resistor, a resistor 11 is sealed and fixed by a cement 16 in a cover member 15 in the form of a ceramic box having an open surface. Resistor 1
As described above, for example, a resistor used as a conventional current detecting resistor such as a copper-nickel-based alloy or a nickel-chromium-based alloy wire having a diameter of about several mm as described above is directly enclosed. The tip 11a of the lead terminal (electrode) projects from the encapsulant 16 made of cement. Therefore, in order to mount the resistor on the printed circuit board, the terminal 11
a may be inserted into the hole of the printed circuit board and fixed by soldering.

FIG. 2 shows a current detecting resistor according to a second embodiment of the present invention. This resistor also employs the conventional resistor 12 shown in FIG. 6 as a resistor as it is, and is sealed in a ceramic box-shaped cover member 15 using cement 16. The resistor 12 is also formed by bending a material such as a copper-nickel-based or nickel-chromium-based alloy in the same manner as described above. As shown, the electrode portion 12a is exposed from the cement 16 which is an encapsulating material and is bent along the lower end outer surface 15b of the box-shaped cover member 15, and the tip portion 12b extends along the outer surface of the cover member 15. Extending upward.

FIG. 3 shows a state where the resistor is mounted on a printed circuit board. The printed circuit board 18 has a wiring layer 19, and the wiring layer 19 has the electrode portions 12 a, 1
2b is connected and fixed by the solder 20. As shown in the drawing, the solder 20 is bonded not only to the lead terminal portion 12a but also to the terminal portion 12b extending upward along the outer surface 15b of the cover member, thereby firmly attaching the resistor 12 to the printed circuit board 18. Is fixed to the wiring layer 19. Therefore, by providing the bent portion 12b above the tip of the electrode portion, it is possible to securely fix the resistor by soldering, and to determine whether the soldered portion is formed well. Can be easily performed visually.

FIG. 4 shows a current detecting resistor according to a third embodiment of the present invention. This resistor also employs the conventional resistor 12 shown in the figure as a resistor as it is, and encapsulates it in a ceramic box-shaped cover member 15 using cement 16. That is, the lead terminal of the metal film resistor 13 is connected to the leg 15a of the ceramic case member.
Electrode portion 14 made of a copper plate or the like formed by bending along
Is connected by welding or the like, and the resistor 13 and the connection portion are embedded in an encapsulant 16 made of cement.
Is exposed to the outside of the encapsulating material 16. Also in this case, the electrode portion 14 is provided on the outer surface 15 of the box-shaped case member.
A tip portion 14b extending upward along the line b is provided, whereby the solderability is improved, and the quality of the soldering at the time of mounting on a printed circuit board can be visually checked.

Here, in the above embodiment, the cover member 15 is made of a steatite-based ceramic material, or a mullite-based ceramic material in the case of particularly high power. As described above, the resistor 11 is embedded with the cement 16 inside the box-shaped cover member 15 having one surface opened, and the surface thereof is substantially flush with the opening surface.
The cement 16 is obtained by mixing a small amount of a silicon resin with a silicon oxide (SiO ₂ ) -based inorganic fine powder and humidifying and curing the mixture. As the dimensions of the box, for example, a length of 13 mm,
The width is 5.5 mm, the height is 5.2 mm, or the length is 18 mm, the width is 6.3 mm, and the height is 6.0 mm.

In the above-described embodiment, an example has been described in which a linear or plate-shaped resistor is bent and a metal film resistor is sealed in a box-shaped case using cement. However, the shape of the resistor is not limited to the above, and other than cement as the encapsulating material,
Similarly, a material having insulating properties, heat conductivity, and easy handling can be used.

[0020]

As described above, according to the present invention,
By fixing the resistor to a case made of ceramics or the like using an encapsulant such as cement or the like, the insulation of the current detection resistor can be improved, and its power capacity can be increased.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a current detecting resistor according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a current detection resistor according to a second embodiment of the present invention.

3A is a perspective view of the current detection resistor shown in FIG. 2, and FIG. 3B is a partially enlarged view showing a state where the current detection resistor is mounted on a printed circuit board.

FIG. 4 is a cross-sectional view of a current detecting resistor according to a third embodiment of the present invention.

FIG. 5 is a perspective view showing an example of a conventional current detection resistor.

FIG. 6 is a perspective view showing another example of a conventional current detecting resistor.

FIG. 7 is a perspective view showing still another example of the conventional current detecting resistor.

[Explanation of symbols]

 1, 12, 13 Resistor (resistor) 12a, 12b Electrode bending part 14 Electrode 15 Box-shaped ceramic case 16 Encapsulant (cement) 18 Printed circuit board 20 Solder

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 2G025 AA01 AA17 AB05 5E028 AA10 BA30 BB01 BB20 CA03 DA02 DA04 EA03 EA14 EA23 EB06 JB01 JB03 5E033 AA00 BC01 BD01 BE01 BH01

Claims (3)

[Claims] 1. A resistor is fixed in a box-shaped cover member having an open insulating surface by using an encapsulating material, and an electrode portion of the resistor is taken out from the encapsulating material. Current detection resistor. 2. The current detection resistor according to claim 1, wherein said encapsulant is cement. 3. The current detecting resistor according to claim 1, wherein a tip of the electrode portion is bent and arranged along a side end surface of the box-shaped cover member.