JP2003177171A - Magnetism variation sensor and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To position accurately a Hall IC in order to reduce the dispersion of detection performance, to prevent penetration of moisture from the interface between a lead frame and a resin used for resin molding or the like, and to prevent a circuit short of an inserted electronic part, or the like, in a magnetism variation sensor of a type for detecting with a magnetic sensor the changing state of a magnetic field by a permanent magnet caused by rotation of an encoder. <P>SOLUTION: The electronic parts such as the Hall IC 2, a control resistance or a capacitor, and a circuit for connecting the electronic parts are arranged on the surface of an insulating holder 7. The electronic parts and the circuit are coated by an elastic resin 8, positioned in a die for injection molding by supporting the holder 7 by a support pin, and resin-molded integrally, to form an armoring case. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic variable sensor used as a rotation sensor for detecting the rotation speed of wheels and a method for manufacturing the same.

[0002]

2. Description of the Related Art As a rotation sensor, a magnetic variable sensor of a type in which a magnetic sensor detects a situation in which a magnetic field generated by a permanent magnet changes due to rotation of an encoder is widely used.

Japanese Patent Laid-Open No. 2001-141738 discloses that
This type of rotation sensor is disclosed. By inserting the control electronic parts and molding the case integrally with the resin, it is possible to prevent dust and other foreign matter from entering the case, and to prevent vibration even with vibration. It states that a sensor can be obtained. Furthermore, electronic components such as Hall ICs, control resistors, and capacitors have a modulus of elasticity of 500 kgf / mm ^2.
By coating with the following elastic resin, due to heat,
It is also described that expansion and contraction of electronic components can be absorbed.

[0004]

In the rotation sensor of the above type, in order to reduce the variation in the detection performance,
It is necessary to accurately position the Hall IC. In the invention described in the above-mentioned publication, when the case is resin-molded, the tie bar of the lead frame is sandwiched so that the parts to be inserted are positioned in the mold for injection molding, and the case is resin-molded. After molding, the tie bar is cut. As a result, the Hall ICs are accurately positioned in the product. However, because of this, the cut end of the tie bar is exposed, and moisture etc. penetrates from the exposed cut end of the tie bar through the interface between the tie bar and the resin molded resin, causing a circuit short circuit of the inserted electronic component. It may happen.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned problems. An insulating holder is prepared, and a Hall IC, a control resistor,
After deploying electronic parts such as capacitors and circuits connecting them, and covering the electronic parts and circuits with elastic resin,
By supporting the holder with a support pin, positioning is performed in a mold for injection molding, and these are integrally resin-molded to form a case.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, electronic components such as Hall ICs, control resistors and capacitors, and circuits connecting these electronic components are provided on an insulating holder to provide electronic components and The circuit is covered with an elastic resin having a sealing property against moisture and the like, and then these are integrally resin-molded to form a case. Here, the holder is P
Molded using a hard insulating plastic such as BT or nylon, the elastic resin has a longitudinal elastic modulus of 5
A resin of 00 kgf / mm ² or less, for example, a silicone resin or a polyamide hot melt resin is used. In addition, as a method of coating an electronic component and a circuit with an elastic resin, for example, 20 kgf / cm ² or less,
Preferably, a method of injection molding with a low molding pressure of 10 kgf / cm ² or less may be used, or a method of applying with a dispenser or the like may be used. After coating with the elastic resin,
The outer case is formed by resin molding including the holder, but the outer case is required to withstand impact such as flying stones, and it is preferable to use nylon resin or epoxy resin containing glass fiber.

[0007]

FIG. 1 shows an example of an embodiment of the present invention, the contents of which will be described with reference to the drawings. In FIG. 1, 7 indicates a holder. The holder 7 has a flat plate shape and is provided with a hole into which a support pin for positioning in the mold can be inserted. Although not shown in the figure, holes are also provided in the upper side of the figure, and the holder 7 is supported from above and below by the support pins to enable accurate positioning. The lead frame 4 is connected to the end of the lead wire 5, and the lead frame 4 is inserted into the mold together with the electronic component 3 covered with the silicone resin and the holder 7,
The holder was positioned in the mold using the support pins, and the outer case 9 was formed by resin molding with epoxy resin containing glass fiber.

In FIG. 1, reference numeral 11 denotes a hole from which a support pin has been removed. This hole penetrates through the outer case 9 and the holder 7
Although the portion is visible, it does not penetrate the holder 7, and the holder 7 and the outer case 9 are in close contact with each other, so that there is no possibility that moisture or the like will enter from the interface. As a result of repeated expansion and contraction due to heat,
Even if the contact between the holder 7 and the outer case 9 is broken in part, the electronic component and the circuit are covered with the elastic resin having the sealing property, and the circuit is not short-circuited.

[0009]

EFFECTS OF THE INVENTION Electronic components such as a Hall IC, a control resistor, and a capacitor are provided in an insulating holder, these electronic components are covered with an elastic resin, and then the holder is supported by a support pin, so that injection is performed. The Hall ICs can be accurately positioned by performing positioning in the molding die and integrally molding the resin to form the outer case, so that variations in detection performance can be reduced. Moreover,
By using the insulative holder, it is possible to obtain a magnetic variable sensor that can block the invasion path of moisture and the like and that does not cause a short circuit of electronic parts.

[Brief description of drawings]

FIG. 1 shows an example of a magnetic variable sensor of the present invention,
(A) is a plan view and (b) is a cross-sectional view.

[Explanation of symbols]

1 Lead conductor 2 hall IC 3 electronic components 4 lead frame 5 Lead wire coating 6 permanent magnet 7 holder 8 elastic resin 9 exterior case 10 Mounting bracket 11 Hole with support pin removed

Claims (2)

[Claims] 1. An insulating holder having electronic parts and circuits on its surface, an elastic resin covering the electronic parts and circuits, and an outer case formed by integrally molding these with resin. A magnetic variable sensor. 2. An electronic component and a circuit are provided on the surface of an insulating holder, the electronic component and the circuit are covered with an elastic resin, and then the holder is supported by a support pin, whereby a mold for injection molding is provided. The method for manufacturing a magnetic variable sensor is characterized in that the outer case is formed by integrally positioning these and resin-molding them.