JPH043483Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to an improvement of a trimmer capacitor.

(Prior Art) As shown in FIG. 2, a conventional trimmer capacitor has a dielectric substrate 21 on which a semicircular stator electrode 22 is formed on the lower surface, and a semicircular protrusion serving as a rotor electrode on the lower surface. Part (rotor electrode part) 2
The rotors 23 having the rotors 2 and 4 are brought into opposing contact, and
The structure is such that the dielectric substrate 21 is unrotatably housed in an insulating case 26 having a through hole a at a portion facing the rotary operation part 25 of No. 3, and the rotor 23 is rotatably housed. The capacitance is adjusted by rotating the rotor electrode 23 and changing the facing area of the rotor electrode section 24 and the stator electrode 22.

However, when this conventional trimmer capacitor is attached and fixed to a circuit board using an adhesive such as solder, flux contained in the solder etc. evaporates and vaporizes from the through hole a formed in the insulating case 26 into the case. This has the disadvantage that objects may get stuck inside the case and solidify inside the case, making it impossible for the rotor 23 to rotate or causing a change in the capacitance value.

Therefore, in order to eliminate the above-mentioned drawbacks of the conventional trimmer capacitor, the through hole a of the insulating case 26 is sealed with a shielding sheet 27 as shown in FIG. A trimmer capacitor that can prevent the capacitor from entering the insulating case 26 through the hole a has already been proposed. (JP-A-58-129632, JP-A-58-148421, JP-A-58-187133
Publication No.).

However, when this trimmer capacitor is attached and fixed to a circuit board, flux contained in solder etc. may enter the insulating case 26 and make it impossible to rotate the rotor 23 or change the capacitance value. Although it can be effectively prevented, if a minute gap is formed at the joint between the insulating case 26 and the shielding sheet 27 to prevent flux from entering, the flux, etc. adhering to the outside after being fixed to the circuit board will be removed. When cleaning and removing hot water or solvent, the hot water or solvent may enter into the insulation case 26 through the minute gap and become interposed between the stator electrode 22 and the rotor electrode section 24 or corrode both electrodes. This has the disadvantage that it causes a change in capacitance value.

(Purpose of the invention) This invention was devised in view of the above-mentioned drawbacks.
To provide a trimmer capacitor that can be reliably adjusted to a desired capacitance value without any hindrance to rotation of a rotor.

(Means for Solving the Problems) The present invention provides a dielectric substrate having a stator electrode and a rotor that is in contact with the dielectric substrate and acts as a rotor electrode, at a portion of the rotor that faces a rotating operation portion. A trimmer capacitor sealed in an insulating case having a through hole, characterized in that the through hole of the insulating case is sealed with a shielding sheet, and at least the joint between the insulating sheet and the shielding sheet is covered with a heat-resistant resin layer. That is.

(Example) Next, the present invention will be described in detail based on an example shown in FIGS. 1a and 1b.

FIG. 1a shows an embodiment of the trimmer capacitor of the present invention, where 1 is a dielectric substrate made of barium titanate porcelain or the like, and 2 is a rotor made of metal.

A semicircular stator electrode 3 is formed on the lower surface of the dielectric substrate 1 . Also, in rotor 2,
A semicircular rotor electrode part 4 that contacts the dielectric substrate 1 and acts as a rotor electrode is formed at the lower part of the rotor electrode part 4, and a member that applies rotational force, such as a driver, is in contact with or inserted in the upper part. A rotation operation section 5 is formed.

The stator electrode 3 is formed on the lower surface of the dielectric substrate 1 by bonding a semicircular metal plate with an adhesive such as glass or resin, or by metallizing a metal powder such as molybdenum or manganese. The rotor electrode portion 4 of No. 2 is formed by subjecting a semicircular portion of the rotor 2 to processing such as etching or laser processing.

The dielectric substrate 1 and the rotor 2 are mounted in a case 11 consisting of a substrate 9 and a cap 10 made of an electrically insulating material, with the dielectric substrate 1 being unrotatably mounted and the rotor 2 being rotatably mounted, respectively. It is enclosed.

A spring portion 8 of a rotor terminal 6 is interposed between the top portion 10a of the cap body 10 of the case 11 and the rotor 2, and the spring stress of the spring portion 8 allows the rotor 2 to freely rotate relative to the dielectric substrate 1. Pressed in close contact. Thereby, the dielectric substrate 1 is sandwiched between the stator electrode 3 and the rotor electrode 4, and a certain electrostatic capacitance is imparted between the two electrodes.

Further, a through hole 10b communicating with the rotary operation section 5 of the rotor 2 is formed in the center of the top of the cap body 10, and the through hole 10b is connected to the thin shielding sheet 1.
It is sealed by 2. This shielding sheet 12 is made of, for example, a Teflon sheet, and the cap body 10
It is attached to the top part 10a with an adhesive such as resin so as to seal the through hole 10b.

The shielding sheet 12 has a small thickness and is easily torn when a member that applies rotational force, such as a screwdriver, is inserted into the rotation operation part 5 of the rotor 2 through the through hole 10b of the cap body 10. Adjustment of the capacitance value is carried out by inserting a rotating force imparting member over the shielding sheet 12.

Further, the joint between the shielding sheet 12 and the cap body 10 is covered with a heat-resistant resin layer 13 made of a heat-resistant resin, such as epoxy resin, and the minute gap existing at the joint is filled with a heat-resistant resin layer 13. It is completely covered by layer 13. As a result, even if the trimmer capacitor is attached and fixed to the circuit board and the flux etc. adhering to the outside is washed away using hot water or a solvent, the hot water etc.
There is no need to go inside.

The heat-resistant resin layer 13 is applied to the shielding sheet 12 and the cap body 10 by a conventionally well-known coating method or spraying method.
and completely cover the joint.

Note that the heat-resistant resin layer 13 is not applied only to the joint between the shielding sheet 12 and the cap 10 as shown in FIG. Those skilled in the art will easily understand that the same effect as the above-mentioned structure can be achieved even if the entire structure is coated. Further, when the heat-resistant resin layer 13 has a thickness in the range of 20 μm to 1 mm, the shielding sheet 12 and the cap body 10
It is possible to completely close the minute gap existing at the joint between the rotor 2 and the rotor 2, and it is also possible to easily insert the rotational force applying member into the rotational operation section 5 of the rotor 2.

The rotor electrode portion 4 of the rotor 2 is connected to the rotor terminal 6 on the end surface and the upper surface of the rotor 2, and the stator electrode 3 is connected to the stator terminal 7. Capacitance is derived between stator terminal 7 and rotor terminal 6.

The rotor terminal 6 and stator terminal 7 are connected to the case 1.
In the extended state, the case 11 consisting of the cap body 10 and the substrate 9 is integrally bonded with an adhesive such as resin to form a completed trimmer capacitor.

In this way, the trimmer capacitor of the present invention is attached and fixed to the circuit board using an adhesive such as solder, and then a rotating force imparting member such as a driver is attached to the shielding sheet 1.
2 is broken and inserted into the rotation operation part 5 of the head of the rotor 2, and the opposing area between the stator electrode 3 and the rotor electrode part 4 is varied by rotating the rotor 2,
The desired capacitance value is adjusted.

(Effects of the invention) According to the trimmer capacitor of the present invention, when it is attached to a circuit board, the through hole of the insulating case of the trimmer capacitor is completely sealed with a shielding sheet, so that adhesives such as solder cannot be used. The contained flux does not enter the case, and the rotor does not become unable to rotate due to the flux.

Furthermore, even if the shielding sheet and the insulating case are cleaned using hot water or solvent after being fixed to the circuit board, the hot water or solvent will still be present in the joint because the joint between the shielding sheet and the insulating case is covered with a heat-resistant resin layer. It does not enter the case through minute gaps, and there is no possibility that hot water or solvent may be present between the stator electrode and rotor electrode, or corrode both electrodes, causing a change in capacitance value. do not have.

Furthermore, since flux, hot water, etc. do not enter the case, the capacitance of the trimmer capacitor can be determined only by the facing area of the stator electrode and rotor electrode, and the desired static capacitance can be achieved simply by rotating the rotor. The capacitance value can be adjusted reliably.

[Brief explanation of the drawing]

FIG. 1a is a sectional view showing one embodiment of the trimmer capacitor of the present invention, FIG. 1b is a sectional view showing another embodiment of the trimmer capacitor of the present invention, and FIGS. 2 and 3 are FIG. 2 is a cross-sectional view of a conventional trimmer capacitor. DESCRIPTION OF SYMBOLS 1... Dielectric substrate, 2... Rotor, 3... Stator electrode, 4... Rotor electrode part, 5... Rotation operation part, 11... Insulation case, 10b... Through hole, 1
2... Shielding sheet, 13... Heat resistant resin layer.

Claims (1)

[Scope of utility model registration request] A dielectric substrate with a stator electrode and a rotor that is in contact with the dielectric substrate and acts as a rotor electrode are connected to a trimmer capacitor enclosed in an insulating case that has a through hole in the portion facing the rotor rotation operation section. A trimmer capacitor characterized in that the through hole of the insulating case is sealed with a shielding sheet, and at least the joint portion of the insulating case and the shielding sheet is covered with a heat-resistant resin layer.