JP4193278B2 - 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 movement such as rotation 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 a detected object such as a gear, as described in, for example, Japanese Patent Application Laid-Open No. 6-174490. This is a molding material which has a magnetoresistive element and is molded with a resin in the hollow part of a bias magnet (magnet part) formed into a hollow cylindrical shape using a thermoplastic resin such as a ferrite plastic magnet. (Integrated circuit part) is penetrated and both are held together.
[0003]
Then, a magnetic field is generated between the bias magnet and the detected object, and a resistance value change generated in the magnetoresistive element due to a change in the magnetic field according to the motion of the detected object is detected from the detected object to the magnetoresistive element to the bias magnet. By detecting with a magnetic circuit, the motion state of the detected object can be detected.
Here, in the assembly of the magnet portion and the integrated circuit portion, the following method has been conventionally employed.
[0004]
First, the molded integrated circuit part and the resin-molded magnet part are temporarily fixed with positioning pins to perform positioning, and at the same time the resin molding (secondary molding) is performed, the magnet part and the integrated circuit part There is a way to complete the fixing with. Also, there is a method of fixing both of the integrated circuit parts by bonding or press-fitting them to the magnet part.
[0005]
[Problems to be solved by the invention]
However, in the method using the positioning pin, the integrated circuit portion and the magnet portion are fixed in the secondary molding. For this reason, for example, when a process that requires fixing both of them, such as adjustment of magnetic characteristics by trimming, is performed before the secondary molding, the method using the positioning pins cannot be used.
[0006]
Moreover, in the fixing method by the said adhesion | attachment, since hardening of an adhesive agent becomes a batch process and requires a process man-hour, cost becomes high. Moreover, the fixing method by press-fitting has a problem that it is difficult to manage the press-fitting load because it is difficult to obtain the dimensional accuracy between the integrated circuit part and the magnet part.
In view of the above problems, the present invention provides a magnetic detection device that can accurately and inexpensively fix a magnet portion molded using a thermoplastic resin and an integrated circuit portion having a magnetoresistive element and molded with resin. An object is to provide a manufacturing method.
[0007]
[Means for Solving the Problems]
The invention according to claim 1 is made by paying attention to the fact that the magnet part is a molded body of a thermoplastic resin, and uses a magnet part (20) having a through hole and is integrated in the through hole. After inserting the circuit portion (10), the magnet portion is fixed to the integrated circuit portion (10) by pressing and deforming a part of the magnet portion (20) while heating , and the integrated circuit portion A recess (13) is formed in a part of the resin (12) in (10), and the magnet part (20) is deformed so that a part of the magnet part (20) is bitten into the recess by heating and pressing the magnet part (20). In the magnet portion (20), the recess portion (22) that is recessed from the outer peripheral surface of the magnet portion is formed in advance in the portion to be deformed, so that the recess portion is more than the other portion in the magnet portion. Forming a thin thin part (21) and a magnet In the heating and pressing of (20), the heater pin (30) made of a heating element whose outer diameter is smaller than the inner diameter of the recess (22) is used, and the heated heater pin is inserted into the recess and the thin wall portion (21). The thin-walled portion is thermally deformed by being pressed against the concave portion (13) of the resin (12) .
[0008]
According to this manufacturing method, since a part of the magnet part is pressed and deformed while being heated, the magnet part and the integrated circuit part are fixed by a kind of caulking, so that the conventional 2 Both of them can be fixed with high accuracy and at low cost without being subjected to subsequent molding, adhesion or press-fitting. Further, as in this manufacturing method, a recess (13) is formed in a part of the resin (12) in the integrated circuit part (10), and a part of the magnet part (20) is bitten into the recess. By doing so, the deformed portion of the magnet portion meshes with the concave portion, so that the integrated circuit portion and the magnet portion can be more firmly fixed.
[0009]
Moreover, if the thin part (21) thinner than the other part in this magnet part is previously formed in the part made to deform | transform in the magnet part (20) like this manufacturing method, it can make it easier to deform | transform. In addition, the code | symbol in the bracket | parenthesis of each said means is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments shown in the drawings will be described below. The magnetic detection device according to the present embodiment is, for example, an engine rotation sensor, a cam angle sensor, a crank angle sensor, a vehicle speed sensor, an AT sensor, a wheel speed sensor, or the like that detects the rotation of a detection target (gear or the like) that rotates. It can be applied as a detection device. FIG. 1 is a schematic cross-sectional view showing a manufacturing process according to the present embodiment, and finally a magnetic detection device 100 shown in FIG. 1C is manufactured.
[0011]
In the magnetic detection device 100 shown in FIG. 1C, reference numeral 10 denotes a mold IC (an integrated circuit portion of the present invention). The mold IC 10 includes a lead frame 11 on which an IC chip, a magnetoresistive element, etc. (not shown) are mounted. Molded to wrap.
[0012]
Reference numeral 20 denotes a magnet (magnet portion of the present invention) formed into a hollow cylindrical shape using a thermoplastic resin. The magnet 20 is formed, for example, by injection molding a material (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, and of course has thermoplasticity. The magnet 20 is supported by a mold IC 10 inserted and fixed in the hollow hole (through hole). In order to prevent rotation of the magnet 20 in the mold IC 10 around the cylindrical axis, the hollow hole has a cross-sectional shape orthogonal to the cylindrical axis such as a square hole shape or a flat hole shape.
[0013]
The magnet 20 is formed with a recessed portion 22 that is recessed from the outer peripheral surface thereof, so that the recessed portion 22 forms a thin portion 21 that is thinner than other portions of the magnet 20. The thin-walled portion 21 is thermally deformed and digged into the concave portion 13 formed in the mold resin 12 to lock the mold IC 10 and the magnet 20, thereby fixing the mold IC 10 and the magnet 20.
[0014]
Here, as shown in FIG. 1C, in the mold IC 10, a portion of the lead frame 11 exposed from the mold resin 12 (the left end portion in the drawing) is electrically connected to an external circuit or the like. The IC chip and the magnetoresistive element are mounted on the end portion of the lead frame 11 opposite to the exposed portion (right end portion in the figure), and are encapsulated in the mold resin 12. Therefore, it is preferable not to form the recess 13 in the mounting portion of the IC chip or the like so as not to be affected by heat or the like due to thermal deformation of the thin portion 21 described above.
[0015]
The detection action of the magnetic detection device 100 is basically the same as that of the conventional one. That is, a magnetic field is generated between the magnet 20 and a detected object such as a gear, and a change in resistance value generated in the magnetoresistive element of the mold IC 10 due to a change in the magnetic field according to the movement of the detected object is detected from the detected object to the mold. By detecting through the magnetic circuit of the IC 10 to the magnet 20, the motion state of the detected object can be detected.
[0016]
Next, a method for manufacturing the magnetic detection device 100 will be described with reference to FIGS.
First, as shown in FIG. 1A, a mold IC 10 and an injection-molded magnet 20 are prepared, and the magnet 20 is inserted into a hollow hole up to a predetermined position so as to obtain a magnetic circuit capable of obtaining desired characteristics. Insert the mold IC 10. When the insertion is completed, the concave portion 13 of the mold IC 10 and the thin portion 21 of the magnet 20 coincide with each other, and these both portions 13 and 21 are respectively connected to the molding portions of the mold and magnet. It is made in advance by forming a corresponding shape.
[0017]
Next, in a state where the heater pin 30 made of a heating element is heated, the heater pin 30 is inserted into the recessed portion 22 of the magnet 20 as shown by an arrow in FIG. 1A, and as shown in FIG. Press against part 21. The thin portion 21 of the magnet 20 which is thermoplastic due to the heat and pressing force of the heater pin 30 is thermally deformed and bites into the recess 13 of the mold resin 12. Thus, the mold IC 10 and the magnet 20 are fixed. Thereafter, the heater pins 30 are pulled apart as shown in FIG.
[0018]
Here, for example, when the thermoplastic resin in the magnet 20 is PPS and the mold resin 12 in the mold IC 10 is an epoxy resin, the thickness of the thin portion 21 is about 1.5 ± 0.5 mm, and the temperature of the heater pin 30 is about By setting the temperature to 320 to 350 ° C., the fixing by the thermal deformation is performed. Since the mold resin 12 is a thermosetting resin and does not melt, the upper limit of the temperature of the heater pin 30 may be determined by a controllable temperature range that is equal to or higher than the melting temperature of the PPS.
[0019]
Further, by making the outer diameter of the heater pin 30 smaller than the inner diameter of the recess 22, contact between the heater pin 30 and the side wall of the recess 22 is avoided. For example, the outer diameter of the heater pin 30 can be 2 mm, and the inner diameter of the recess 22 can be 3 mm.
The mold IC 10 and the magnet 20 which are assembled and fixed by the above manufacturing method avoid the deviation in the insertion direction of the mold IC 10 by biting into the concave portion 13 of the thin portion 21, and as described above, the magnet 20 Since the hollow hole (through hole) has a square hole shape or the like, rotation around the cylindrical axis of the magnet 20 in the mold IC 10 is prevented.
[0020]
As described above, according to the present embodiment, the mold IC 10 and the magnet 20 can be obtained by pressing and deforming the thin portion 21 of the magnet 20 while heating the mold IC 10 and the magnet 20 in a desired arrangement. Therefore, both of them can be fixed with high accuracy and at low cost without using secondary molding, adhesion, or press fitting as in the prior art.
[0021]
Moreover, in this embodiment, since the thin part 21 thinner than the other part in the magnet 20 is previously formed in the part to be deformed in the magnet 20, it can be more easily deformed.
In the above-described embodiment, the mold IC 10 and the magnet 20 are formed by forming the recess 13 in the mold resin 12, deforming the thin portion 21 of the magnet 20 so as to bite into the recess 13, and engaging with the recess 13. The magnet 20 is caught on some part of the surface of the mold resin 12 so that the mold IC 10 does not come out of the hollow hole without forming the recess 13 in the mold resin 12. It only has to be deformed and locked.
[Brief description of the drawings]
FIG. 1 is a process diagram showing a method of manufacturing a magnetic detection device according to an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Mold IC, 12 ... Mold resin, 13 ... Recessed part, 20 ... Magnet, 21 ... Thin part.

Claims (1)

A magnet part (20) that is molded using a thermoplastic resin and generates a magnetic field between the object and a magnetoresistive element that causes a change in resistance value due to a change in the magnetic field in accordance with the motion of the object to be detected. And an integrated circuit part (10) molded with resin (12),
A method of manufacturing a magnetic detection device in which the magnet portion and the integrated circuit portion are assembled and fixed,
Using the magnet part (20) having a through-hole, and inserting the integrated circuit part (10) into the through-hole, then pressing and deforming part of the magnet part while heating, Fixing the magnet part to the integrated circuit part ;
A concave portion (13) is formed in a part of the resin (12) in the integrated circuit portion (10), and a part of the magnet portion is bitten into the concave portion by heating and pressing the magnet portion (20). To be transformed into
In the magnet portion (20), the portion to be deformed is previously formed with a recess portion (22) that is recessed from the outer peripheral surface of the magnet portion, so that the recess portion is thinner than the other portions of the magnet portion. Forming a thin-walled portion (21),
The heating pressing of the magnet part (20) uses the heater pin (30) made of a heating element whose outer diameter is smaller than the inner diameter of the hollow part (22), and inserts the heated heater pin into the hollow part. A method of manufacturing a magnetic detection device , wherein the thin-walled portion (21) is thermally deformed by being pressed against the thin-walled portion (21) so as to bite into the concave portion (13) of the resin (12). .

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