JPH077733B2 - Sliding contact device - Google Patents

Description

The present invention relates to a volume switch, potentiometer, and potentiometer used for detection, control, setting, oscillator, etc. in measuring instruments, various machines, etc. Trimmer (a type of variable resistor)
The present invention relates to an improvement of a sliding contact device used in the above.

(Prior art and its problems) Sliding contact devices conventionally used in the above volume switches, potentiometers, trimmers, etc. have carbon (C) and ruthenium oxide (RuO ₂ ) on a ceramic substrate.
Ag is applied to a wiring board made by firing a resistance paste such as to form a thick film resistance pattern and a spring terminal material that can slide against the thick film resistance pattern of this wiring board.
The sliding contact device is composed of a sliding contact formed by crimping or welding a contact material, but this sliding contact device is liable to generate noise, has a slightly high contact resistance and is unstable due to some variation. Moreover, it was easily worn, had a short life, and lacked contact reliability.

Therefore, the portion of the thick film resistance pattern of carbon or ruthenium oxide on the ceramic substrate that slides with the sliding contact should be
-The contact reliability is improved by replacing it with a Pb-based conductor paste and firing it, or by stacking and firing the Ag-Pd-based conductor paste on the part that slides on the sliding contact of the thick film resistance pattern. Ag contact material of Ag-
Pd is replaced with 30-50 wt%.

However, since the thick film resistance pattern and the contact material are the same kind of combination, adhesion and peeling easily occur, and wear is promoted. or
The contact material of Ag-Pd 30 to 50 wt% is too hard at Hv160 to 200, while the thick film conductor pattern, which is a fired product of Ag-Pd-based conductor paste, is soft and wears a lot, leading to early life. . Furthermore, the Ag-Pd 30 to 50 wt% contact material has an electrical conductivity (IA
Since CS3.8 to 5.5) is low, there were problems such as heat generation.

(Object of the Invention) It is an object of the present invention to provide a sliding contact device that can solve the above problems.

(Means for Solving Problems) A sliding contact device of the present invention for solving the above problems is formed by forming a thick film resistance pattern by firing a resistance paste on a ceramic substrate. Connect to the pattern
A wiring board made by firing an Ag conductor paste to form a thick film conductor pattern and a contact material of Ag to Cu3 to 20 wt% that can slide against the thick film conductor pattern of this wiring board is a spring. It is characterized by comprising a sliding contact mounted on a terminal material.

In the sliding contact device of the present invention, the contact material of the sliding contact is Ag
-The reason for setting Cu3 to 20wt% is that if the Cu content in Ag is less than 3wt%, the lubrication effect is small, and the sliding contact is
This is because adhesion and peeling occur in contact with the thick film conductor pattern, and when it exceeds 20 wt%, oxides are generated and cause noise.

(Operation) In the sliding contact device configured as described above, in the contact action between the sliding contact and the thick film conductor pattern on the ceramic substrate, the hardness of the contact material is Ag-Cu3 to 20 wt% (Hv110 to
150) is soft and slippery, so the contact resistance is low and stable, and the Ag thick film conductor pattern is not damaged.
Also, since adhesion and peeling are almost eliminated and wear is reduced, good contact can be obtained. In addition, Ag-Cu3 to 20wt% of sliding contact
Since the electrical conductivity of the contact material is as good as IACS 80-95%,
No fever.

(Example 1) An example of the sliding contact device of the present invention will be described. As shown in the figure, RuO ₂ with a width of 3 mm on the outer periphery of an Al ₂ O ₃ substrate 1 having a plate thickness of 0.6 mm and a diameter of 30 mm and a purity of 98%. Screen printing of the resistance paste of No. 2 and baking at 800 ° C. to form a thick film resistance pattern 2 having a thickness of 10 μ, connecting to this thick film resistance pattern 2 and screen printing with Ag conductor paste in the circumferential direction, By firing at 800 ° C., a thick film conductor pattern 3 having a width of 0.2 mm, a length of 7 mm and a thickness of 10 μ was formed at intervals of 0.2 mm to obtain a wiring board 4. On the other hand, the two types of sliding contacts 5 which are adapted to slide respectively facing the thick film conductor pattern 3 of the wiring board 4 are Ag-Cu 7.5 wt% and A
Two types of head diameter 3mm, head thickness 0.6mm, leg diameter 1.5mm, leg length 1.5mm made from two types of contact wire material (direct type 1.5mm) of g-Cu16.0wt% -nickel 0.1wt% The rivet contacts 6 are inserted into the contact mounting holes of the spring terminal material 7 made of Be-Cu each having a width of 4 mm and a thickness of 0.15 mm.

A sliding contact device of Examples 1 and 2 configured in this way,
Ag-Pd30 wt% Soil contact with contact material Wiring board Ag-Pd30
A sliding contact test was conducted on a conventional sliding contact device formed by facing a wt% thick film introduction pattern, and the results shown in the following table were obtained.

Test condition Contact force: 10g, Operation: Reciprocating rotation type (55 degrees), Drive: 60 strokes / min, Energization: 12V, 100mA As is clear from the above table, it is understood that the sliding contact devices of Examples 1 and 2 generally have a doubled life as compared with the sliding device of the conventional example. This is all about the contact 5 Ag-Cu3-20w
Since the hardness of the t-contact material is soft and slippery, there is no wear on the opposing Ag thick film conductor pattern 3, no adhesion or peeling, and less wear. Ag-Cu3-20wt
% The electrical conductivity of the contact material is good and no heat is generated.

The above-mentioned life is due to the wear of the thick film conductor pattern 3.
It was determined that the sliding contact 5 was in contact with the Al ₂ O ₃ substrate and was in an open state (infinite contact resistance), and that the slit portion between the thick film conductor patterns 3 was short-circuited.

The wiring board 4 of the sliding contact device of the above embodiment is circular, but may be rectangular. In that case, the thick-film resistance pattern may be formed on one end of the rectangular wiring board, and the thick-film conductor pattern may be connected to the thick-film resistance pattern and formed parallel to the longitudinal direction at regular intervals. The sliding contact faces the thick film conductor pattern and can slide in the longitudinal direction of the thick film resistance pattern. In addition, a thick-film resistance pattern that reciprocates back and forth in a bellows shape is formed on a ceramic substrate, and a thick-film conductor pattern is formed on the thick-film resistance pattern arranged at regular intervals. The sliding contact device may be a sliding contact device configured to slide by sliding.

Further, as in Example 2, part of Cu may be replaced with an iron group element in the range of 0.01 to 1 wt.

(Effects of the Invention) As can be seen from the above description, the sliding contact device of the present invention has a hardness (Hv110 to 150) of Ag-Cu3 to 20 wt% of the sliding contact is soft and slippery. Since the Ag thick film conductor pattern of No. 1 is not worn, and adhesion and peeling are almost eliminated and wear is reduced, good contact can be obtained.

Therefore, the contact reliability is improved and the life of the sliding contact device is significantly extended. Further, since the contact material of Ag-Cu3 to 20 wt% of the sliding contact has a good electric conductivity, the contact action does not generate heat and the welding hardly occurs. Therefore, the welding resistance of the sliding contact device is significantly improved.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing an embodiment of the sliding contact device of the present invention.

Claims (1)

[Claims] 1. A wiring formed by firing a resistance paste on a ceramic substrate to form a thick-film resistance pattern, connecting the thick-film resistance pattern and firing an Ag conductor paste to form a thick-film conductor pattern. The board and the thick film conductor pattern of this wiring board can be made to slide opposite to each other.
% Of the contact material is attached to the spring terminal material, and the sliding contact is formed.