JP4131183B2 - Method for manufacturing magnetic detection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing a magnetic detection device that detects a motion of a detection object using a change in resistance value of a magnetoresistive element.
[0002]
[Prior art]
As this type of magnetic detection device, there is one that detects the rotation of an object to be detected such as a gear, as described in Patent Document 1. This is because, for example, an integrated circuit portion (hereinafter referred to as “resin”) having a magnetoresistive element in a hollow portion of a magnet portion (bias magnet) formed in a hollow cylindrical shape using a resin like a ferrite-based plastic magnet (hereinafter referred to as “an integrated circuit portion”). The mold IC is called) and both are integrated.
[0003]
Here, in assembling the magnet part and the mold IC, conventionally, the mold IC is inserted and bonded to the cylindrical magnet part, or the mold IC is press-fitted into the magnet part and fixed, or Has adopted a method in which both are integrated by insert molding in which a mold IC is placed in an injection mold of a magnet part and the magnet part is resin-molded (see, for example, Patent Document 2).
[0004]
[Patent Document 1]
JP-A-6-174490 [0005]
[Patent Document 2]
Japanese Patent Laid-Open No. 2000-298134
[Problems to be solved by the invention]
However, in the method in which the mold IC is inserted and bonded to the magnet portion, the adhesive curing is a batch process, which requires man-hours, resulting in an increase in cost. Further, in the fixing method by press-fitting, since strict precision is required for parts and assembly, manufacturing cost and assembly cost increase. Moreover, in the method of integrating by insert molding, since positioning of mold IC is performed with the external shape of the said mold IC, positioning accuracy is low, and as a result, the relative positional accuracy of a magnet part and mold IC becomes low.
[0007]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method of manufacturing a magnetic detection device capable of integrating a magnet portion and a mold IC efficiently, accurately, and inexpensively.
[0008]
[Means for Solving the Problems]
The present invention attaches a plurality of integrated circuit portions having magnetic detection elements to a lead frame, molds these integrated circuit portions with a mold resin, and when the lead frame is set, fits into a guide hole formed in the lead frame. A positioning die is prepared by molding a mold having a plurality of cavities formed so as to surround each molding resin molded with a positioning pin and an integrated circuit portion, and a lead frame is fitted into the molding die and a guide hole is fitted into the positioning pin. The resin that forms the magnet part is injected into the cavity and the magnet part is molded into a cylindrical shape so as to surround each mold resin that molds the integrated circuit part, and then the mold resin that molds the integrated circuit part In addition, the magnet part is separated from the lead frame.
[0009]
Further, the present invention attaches a plurality of integrated circuit portions to a lead frame, molds each integrated circuit portion with a mold resin, and when the lead frame is set, fits into a guide hole formed in the lead frame. By preparing a molding die having a plurality of cavities located on at least one of both sides of the molding resin molding the positioning pin and each integrated circuit portion, and fitting the lead frame to the molding die and the guide hole to the positioning pin Molded resin and magnet that are set in a positioning state, injecting resin constituting the magnet part into the cavity and molding the integrated circuit part, molding the magnet part on at least one side, and then molding the integrated circuit part The part is separated from the lead frame.
[0010]
According to such means, the guide hole of the lead frame is fitted into the positioning pin of the molding die, thereby positioning the molding resin of each mold resin molded with the integrated circuit portion. As a result, the relative positional accuracy between the integrated circuit portion and the magnet portion can be excellent. In addition, since a plurality of molded integrated circuit portions and magnet portions can be integrated at a time, they can be manufactured efficiently and the cost can be reduced.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
The magnetic detection device 1 of the present embodiment is used in combination with, for example, a gear provided on the rotating side to detect rotational motion of an engine rotation sensor, cam angle sensor, crank angle sensor, vehicle speed sensor, and the like. It can be applied as a device.
The overall configuration of the magnetic detection device 1 is shown in FIG. As shown in the figure, the magnetic detection device 1 is provided with a cylindrical bias magnet portion 3 on the outer periphery of a flat mold IC 2.
[0012]
The mold IC 2 is obtained by molding an IC chip (integrated circuit portion) having a magnetoresistive element (not shown) mounted on a lead frame 4 described later so as to be wrapped with a molding resin 5 made of a thermoplastic resin such as epoxy. In the IC chip, an integrated circuit constituting a processing circuit for a detection signal output from the magnetoresistive element is formed.
[0013]
Here, the mold IC 2 has a portion that is separated from the lead frame 4 and protrudes outward from one end portion of the molding resin 5, and this protruding portion is a terminal portion 4 a that is electrically connected to an external circuit or the like. Configure. A magnetic detection element and an IC chip (not shown) are embedded in the molding resin 5 and in the end opposite to the terminal portion 4a.
[0014]
The magnet portion 3 is formed by molding a plastic magnet material in which a magnetic powder such as ferrite is mixed with a thermoplastic resin such as PPS (polyphenylene sulfide) as a binder.
[0015]
The detection action of such a magnetic detection device 1 is the same as that of the prior art. A magnetic field is generated between the magnet portion 3 and the detection body such as a gear, and the change of the magnetic field according to the movement of the detection body causes the mold IC 2 to change. By detecting a change in resistance value generated in the magnetoresistive element through the magnetic circuit of the detector, the mold IC 2 and the magnet unit 3, the motion of the detector is detected.
[0016]
Next, a method for manufacturing the magnetic detection device 1 will be described with reference to FIGS. First, the lead frame 4 for mounting and molding an IC chip (not shown) is formed from a metal plate such as copper, and as shown in FIG. 2, a plurality of, for example, six IC chips can be attached. Yes. FIG. 3 shows a part of the lead frame 4, that is, a part to which one IC chip is attached. As shown in FIG. 3, the lead frame 4 includes an IC chip (not shown) in addition to the terminal portion 4 a described above. And a portion (embedded portion) 4b embedded in the mold resin 5 and a portion (embedded portion) 4c embedded in the magnet portion 3, and these portions 4a to 4c are connected to the lead frame 4 by tie bars 4d. It is connected with. A large number of guide holes 4e for positioning with respect to a mold (not shown) of the molding resin 5 are formed at both edge portions of the lead frame 4. In addition, a hole 4f is formed in the portion 4c embedded in the magnet portion 3 so that the resin constituting the magnet portion 3 can be satisfactorily connected to the upper and lower side portions of the portion 4c in the figure.
[0017]
On the other hand, a mold 6 for molding the magnet portion 3 is shown in FIG. As shown in the figure, the mold 6 includes a fixed mold 7 and a movable mold 8, and cores 9 and 10 are fixed to both molds 7 and 8. The core 9 of the fixed mold 7 is formed with a shallow rectangular recess 11 into which the lead frame 4 is fitted, and a positioning pin 12 that is fitted into the guide hole 4 e of the lead frame 4 is projected. Yes. The cores 9 and 10 of both molds 7 and 8 are formed with holes 13 and 14 having semicircular cross sections, respectively. These holes 13 and 14 clamp the fixed mold 7 and the movable mold 8 together. When this is done, a cylindrical cavity C for molding the magnet portion 2 is formed.
[0018]
In order to manufacture the magnetic detection device 1, first, a plurality of IC chips are attached to the lead frame 4, and then the lead frame 4 is set in a molding die (not shown) and not shown by the molding resin 5. Mold the IC chip.
[0019]
Thereafter, the lead frame 4 is set on the mold 6 of the magnet unit 3. That is, the lead frame 4 is fitted into the recess 11 of the fixed mold 7 in a mold open state in which the movable mold 8 is separated from the fixed mold 7. At this time, the lead frame 4 is correctly positioned by fitting the guide hole 4 e of the lead frame 4 to the positioning pin 12.
[0020]
Then, the movable mold 8 is moved to a clamped state in which the movable mold 8 is abutted against the fixed mold 7, and in this state, a plastic magnet material resin is injected into the cavity C. Then, the plastic magnet material is filled in the cavity C so as to enclose the mold IC 2, and is formed as the magnet portion 3. Since the magnet part 3 molded in this way has the portion 4c of the lead frame 4 embedded therein, it does not come off the mold IC2.
[0021]
After the magnet portion 3 is molded, the lead frame 4 is taken out of the molding die 6 and set on a press (not shown) to cut the tie bar 4d of the lead frame 4. As a result, the magnetic detection device 1 (the mold IC 2 with the terminal portion 4 a and the magnet portion 3) is separated from the lead frame 4.
[0022]
As described above, according to the present embodiment, the magnet portion is formed by insert molding in a state where the lead frame 4 is accurately positioned by fitting the guide hole 4e and the positioning pin 12 without separating the mold IC 2 from the lead frame 4. 3 is formed, the relative positional accuracy between the mold IC 2 and the magnet portion 3 is excellent. That is, in the method of inserting a mold IC into a cylindrical magnet part and bonding them together, the relative positional accuracy between the two due to the presence of the fitting gap was about 0.25 mm. Positioning accuracy by the positioning pins 12 is as high as about 0.05 mm, so that the mold IC 2 and the magnet portion 3 can be integrated with high positional accuracy.
In addition, since a plurality of magnet portions 3 can be formed at a time, and in this embodiment, six magnet portions can be formed at a time, the productivity is excellent and the cost can be reduced.
[0023]
5 and 6 show another embodiment of the present invention. This embodiment is different from the above-described embodiment in that the magnetism detection device 15 is formed with a pair of magnet portions 16 on both sides of the mold IC 2 as shown in FIG.
That is, the mold IC 2 is flat like the above-described embodiment, and the portion 4 b of the lead frame 4 is embedded in the molding resin 5, and the terminal portion 4 a protrudes from one end. A pair of magnet portions 16 are provided on both the left and right sides of the molding resin 5, and a portion 4 c of the lead frame 4 is embedded in the magnet portion 16.
[0024]
In FIG. 5 showing a molding die 17 for molding the magnet portion 16, holes 18 are formed in the cores 9 and 10 of the fixed die 7 and the movable die 8 so as to be positioned on both sides of the mold IC 2. The hole portion 18 constitutes a cavity D for molding the magnet portion 16 when the fixed die 7 and the movable die 8 are clamped.
[0025]
In the manufacturing method of the magnetic detection device 1 of this embodiment, first, as in the above-described embodiment, an IC chip (not shown) is attached to the lead frame 4 and the mold resin 5 is formed by a mold. Thereafter, the lead frame 4 is set on the molding die 17 of the magnet part 16 and the magnet part 16 is injection molded. Then, after forming the magnet portion 16, the tie bar 4 d is cut to separate the magnetic detection device 15 from the lead frame 4.
[0026]
The present invention is not limited to the embodiment described above and shown in the drawings, and can be expanded or changed as follows.
The magnet unit 3 may be cylindrical, and may be cylindrical or rectangular.
The magnet part 16 may be on either one side instead of a pair.
Any number of IC chips may be attached to the lead frame 4.
Of the lead frame 4, the shapes of the portions 4 b and 4 c embedded in the mold resin 5 and the magnet portions 3 and 16 may be arbitrary.
You may comprise a magnetoresistive element and a processing circuit with a separate IC chip.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a magnet part mold according to an embodiment of the present invention. FIG. 2 is a plan view of a fixed mold in a state where a lead frame is set. FIG. 3 is a plan view of a lead frame provided with a mold IC. FIG. 4 is a perspective view of a magnetic detection device. FIG. 5 is a view corresponding to FIG. 1 showing another embodiment of the present invention. FIG. 6 is a view corresponding to FIG.
In the figure, 1 and 15 are magnetic detection devices, 2 is a mold IC, 3 and 15 are magnet parts, 4 is a lead frame, 4e is a guide hole, 5 is a resin for molding, 6 and 17 are molds, and 12 is a positioning pin. , C and D are cavities.

Claims (2)

A magnet part that is molded using a resin and generates a magnetic field between the object to be detected and a magnetoresistive element that causes a change in resistance value due to a change in magnetism according to the motion of the object to be detected. A method of manufacturing a magnetic detection device comprising a molded integrated circuit unit,
A plurality of the integrated circuit portions are attached to a lead frame, and these integrated circuit portions are respectively molded with the molding resin,
When the lead frame is set, a molding having a plurality of cavities formed so as to surround the molding resin molding the positioning pins and the integrated circuit portions which are fitted into the guide holes formed in the lead frame. Prepare the mold,
The lead frame is set in the mold and the guide hole is fitted to the positioning pin to be set in a positioning state, and the resin constituting the magnet portion is injected into the cavity to mold the integrated circuit portion. The magnet part is molded into a cylindrical shape so as to surround the mold resin,
Then, the method of manufacturing a magnetic detection device, wherein the mold resin and the magnet portion molded with the integrated circuit portion are separated from the lead frame. Resin for molding having a magnet part that is molded using a resin and generates a magnetic field between the object and a magnetoresistive element that causes a change in resistance due to a magnetic change according to the motion of the object to be detected A method of manufacturing a magnetic detection device comprising an integrated circuit portion molded by
A plurality of the integrated circuit portions are attached to a lead frame, and these integrated circuit portions are respectively molded with the molding resin,
When the lead frame is set, a plurality of positioning pins that fit into guide holes formed in the lead frame and a plurality of cavities located on at least one side of each mold resin molding each integrated circuit portion Prepare a mold with
The lead frame is set in the mold and the guide hole is fitted to the positioning pin to be set in a positioning state, and the resin constituting the magnet portion is injected into the cavity to mold the integrated circuit portion. Molding the magnet part on at least one side of the mold resin;
Then, the method of manufacturing a magnetic detection device, wherein the mold resin and the magnet portion molded with the integrated circuit portion are separated from the lead frame.

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