JPH04256301A - Variable resistor - Google Patents

Abstract

PURPOSE:To stabilize the attitude of a variable resistor at the time when the resistor is mounted on a printed wiring board, to generate hardly the positional deviation of the resistor to a circuit pattern and to improve the connection strength of the resistor by a method wherein the widths of lead terminals arranged on the bottom of a case are made wide. CONSTITUTION:An Ag-Pd conductor paste is printed and fired on the upper surface of an insulating board 1 consisting of alumina ceramic or the like to form terminal electrodes 2a and 2b and a current collecting electrode 3 and a horseshoe-shaped resistor 4 is printed and fired. Then, metallic lead terminals 5a, 5b and 5c of a U-shaped section are respectively connected to the electrodes 2a, 2b and 3. Here, the widths of the terminals 5a and 5c are set to be some 1/3 of the short-side width of a case 6. The width of the terminal 5b is almost made equal to the short-side width of the case 6.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable resistor, and more particularly to improvements in the shape of its electrodes.

0002

2. Description of the Related Art Conventionally, this type of variable resistor has a current collecting electrode 3 at the center of the upper surface of an insulating substrate 1, and a horseshoe-shaped shape approximately concentrically arranged around the outer periphery of the current collecting electrode 3, as shown in FIG. Resistor 4
are disposed, and tied end electrodes 2a, 2b are provided at both ends of this resistor, and metallic lead terminals 5a, 5b, 5c are electrically connected to the current collecting electrode 3 and the termination electrodes 2a, 2b. Next, as shown in FIG. 10, the resistor element having the configuration shown in FIG. 9 was subjected to insert molding using an insulating resin, so that an opening was formed on the top surface and parts of the lead terminals 5a, 5b, and 5c were exposed at both ends. Case 6 is formed. At this time, each of the lead terminals 5a, 5b, and 5c exposed from both ends of the case 6 has a width of about ⅓ of the width of the short side of the case 6.

Next, as shown in FIG. 8, a rotary plate 7 with a metal slider 8 arranged by heat caulking or the like is inserted into the opening of the case 6 with the slider 8 facing downward, and the upper surface is A top cover 9 made of metal is attached via a rubber O-ring 10. Further, as shown in FIG. 7, there is a driver groove 11 in the adjusting protrusion on the upper surface of the rotary plate 7, so that the rotary plate 7 can be accessed from the outside.
The structure is such that the resistance value can be changed by rotating.

0004

[Problems to be Solved by the Invention] In the variable resistor of this conventional structure, the widths of the lead terminals 5a, 5b, and 5c, two and one lead terminals respectively arranged on the short side of the bottom of the case 6, are narrower than the width of the case 6. (approximately 1/3 of the width of the short side of the case) Moreover, since it protrudes from the bottom of the case 6, when mounted on a printed wiring board (not shown), the posture is unstable, causing misalignment and a reduction in connection strength. It became.

The purpose of the present invention is to eliminate the conventional drawbacks, to ensure a stable posture when mounted on a printed wiring board, to prevent misalignment with the circuit pattern, and to reduce the contact area between the circuit pattern and the lead terminal. An object of the present invention is to provide a variable resistor that has a wider area and a connection strength that is several orders of magnitude stronger than conventional products.

[0006]

[Means for Solving the Problems] The variable resistor of the present invention includes:
an insulating substrate on which a horseshoe-shaped resistor and a plurality of electrode sections are adhered; an insulating resin case that covers all of the resistor and an area excluding a part of the electrode section; and an insulating resin case that is closely connected to the electrode section and In a variable resistor having lead terminals having an L-shaped cross section that are drawn out from both ends of the case, the width of at least one of the lead terminals is approximately equal to the short side of the bottom surface of the case.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to FIGS. 1 to 4. First, as shown in FIG. 3, after printing and firing an Ag-Pd based conductor paste on the upper surface of an insulating substrate 1 made of alumina ceramic or the like to form terminal electrodes 2a, 2b and a current collecting electrode 3, a horseshoe-shaped resistor is formed. The body 4 is printed and fired.

Next, the terminal electrodes 2a, 2b and the current collecting electrode 3
Metal lead terminals 5a, 5c, 5b each having a U-shaped cross section.
Connect. At this time, the lead terminals 5a and 5c have a width of 1 mm, which is about 1/3 of the width of the short side of the case 6, as shown in FIG. 2mm), which is approximately the same width as 3mm.

Next, insert molding is performed on the resistor element configured as shown in FIG. 3 using an insulating resin such as PPS (polyphenylene sulfide), and as shown in FIG. Lead terminals 5a, 5b
, 5c are partially exposed.

Next, as shown in FIG. 2, a rotary plate 7 with a metal slider 8 arranged by heat caulking or the like is inserted into the opening of the case 6 with the slider 8 facing downward. Assembly of the variable resistor as shown in FIG. 1 is completed by attaching the upper cover 9, which is punched and formed from metal such as stainless steel and has a substantially U-shaped cross section and opens downward, via a rubber O-ring 10. .

By applying a screwdriver or the like to the driver groove 11 provided on the top surface of the rotary plate 7 in FIG. 1 and rotating the rotary plate 10 by a predetermined angle, the slider 8 slides on the top surface of the resistor 4. , so that a desired resistance value can be obtained.

FIG. 5 is a perspective view of a variable resistor showing a second embodiment of the present invention, and FIG. 6 is a perspective view showing the state of connection between the electrodes and lead terminals of the variable resistor shown in FIG. The difference from Example 1 is that each side of the lead terminal 5b has a width of 0.4 mm.
This is because a notch 12 having a depth of 0.9 mm is provided.

In this embodiment, when surface mounting the variable resistor on a printed circuit board, hybrid IC, etc., heat conduction from the lead terminal 5b is minimized and the connection strength between the lead terminal 5b and the current collecting electrode 3 is reduced. There is an advantage in not allowing

[0014]

[Effects of the Invention] As explained above, the present invention has widened the width of the lead terminal arranged on the bottom of the case.
When mounted on a printed wiring board (not shown), the posture is stable and misalignment with the circuit pattern is less likely to occur.In addition, the contact area between the circuit pattern and the lead terminal is wider, and the connection strength is significantly higher than that of conventional products. It has the effect of becoming stronger.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a variable resistor according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line A-A of the embodiment of the present invention shown in FIG.

FIG. 3 is a perspective view showing a connection state between electrodes and lead terminals in one embodiment of the present invention shown in FIG. 1;

FIG. 4 is a plan view of the resistor element of FIG. 3 subjected to insert molding.

FIG. 5 is a perspective view of a variable resistor according to another embodiment of the present invention.

6 is a perspective view showing a connection state between electrodes and lead terminals of the variable resistor shown in FIG. 5; FIG.

FIG. 7 is a perspective view of an example of a conventional variable resistor.

8 is a sectional view taken along line BB of an example of the conventional variable resistor shown in FIG. 7. FIG.

9 is a perspective view showing a connection state between electrodes and lead terminals of the conventional variable resistor shown in FIG. 7. FIG.

10 is a plan view of the resistor element of FIG. 9 subjected to insert molding; FIG.

[Explanation of symbols]

1 Insulating substrate 2a, 2b Terminal electrode 3　　　　　　　　　　　Collecting electrode 4 Resistor 5a, 5b, 5c Lead terminal 6 Case 7 Rotating plate 8 Slider 9 Top lid 10 O-ring 11 Driver groove 12 Notch part

Claims (2)

[Claims] 1. An insulating substrate having a horseshoe-shaped resistor and a plurality of electrode parts adhered to the upper surface thereof, and a case made of an insulating resin that covers all of the resistor and a region excluding a part of the electrode part.
In a variable resistor having a lead terminal connected to the electrode portion and having an L-shaped cross section and drawn out from both ends of the case, the width of at least one of the lead terminals is approximately equal to the short side of the bottom surface of the case. A variable resistor characterized in that it has dimensions. 2. The variable resistor according to claim 1, wherein the lead terminal having a width approximately equal to the short side of the bottom surface of the case has notches on both sides of the lead terminal.