JP4281537B2 - Rotation detection sensor device - Google Patents

Description

  The present invention relates to a rotation detection sensor device in which an IC chip having a magnetoresistive element is fixed to a groove after a part of a bias magnet having a groove is covered with a mold resin.

  The present applicant has applied for a rotation detection sensor device in which a non-resin molded IC chip is directly bare-chip mounted in a groove provided in a bias magnet in Non-Patent Document 1.

  This rotation detection sensor device (hereinafter referred to as sensor device) can be formed as follows. First, a biasing magnet (ferrite magnet) having a groove (substantially U-shaped cross section) is prepared, and the magnet is used as an insert part and insert-molded into a mold resin (first case) so that the groove is not covered. Then, after insert molding, an unmolded IC chip (MRE chip) is directly bonded to the exposed groove bottom surface.

Since the IC chip is directly fixed to the bias magnet in this manner, the IC chip can be mounted on the bias magnet with high accuracy, and the positional deviation between the magnetoresistive element and the bias magnet is small (that is, the sensitivity of the sensor device). Can be improved). In addition, the number of parts can be reduced (the manufacturing process can be reduced).
Japanese Patent Application No. 2003-96379

  However, when the above-described sensor device is downsized, the contact area between the bias magnet and the mold resin is reduced (for example, only the opposing surface (flat surface) of the bottom surface of the groove of the bias magnet is in contact with the mold resin). Therefore, the bias magnet may fall off from the mold resin due to an impact or the like in the manufacturing process of the sensor device.

  In view of the above problems, an object of the present invention is to provide a rotation detection sensor device that can prevent a bias magnet from falling off.

In order to achieve the above object, the rotation detection sensor device according to claim 1 includes a biasing magnet having a groove and an IC chip including a chip having a magnetoresistive element so that the groove is exposed. A part of the bias magnet as the insert part is coated (insert molding) by injection of mold resin , and then the bare chip IC chip is directly fixed (bare chip mounting) to the bottom of the groove. The bias magnet has at least one of a convex portion and a concave portion in at least a part of a portion in contact with the mold resin.

  According to the present invention, since the bias magnet has at least one of the convex portion and the concave portion in at least a part of the portion in contact with the mold resin, the area where the bias magnet is in contact with the mold resin is increased. The mold resin filled in the convex portion of the bias magnet or the concave portion of the bias magnet serves as an anchor. Therefore, since the bias magnet is more stably fixed to the mold resin than when the bias magnet does not have a convex portion and a concave portion at a portion in contact with the mold resin, the bias magnet can be prevented from falling off. it can.

The rotation detection sensor device according to claim 2 includes a bias magnet having a groove portion and an IC chip including a chip having a magnetoresistive element, and the bias magnet as an insert component so that the groove portion is exposed. after a portion of the is covered by the injection of molding resin (insert molding), in which a bare chip of the IC chip is disposed (bare chip mounting) in the groove. The mold resin is in contact with the groove bottom surface of the bias magnet and the opposed surface of the groove bottom surface, and the IC chip is fixed to the groove bottom surface via the mold resin in a state of being disposed in the groove portion . It is characterized by that.

According to the present invention, the mold resin is in contact with the groove bottom surface of the bias magnet and the opposing surface of the groove bottom surface. That is, the biasing magnet is sandwiched and fixed by the mold resin. Therefore, since the bias magnet is stably fixed to the mold resin, it is possible to prevent the bias magnet from falling off. In addition, since the chip having the magnetoresistive element as the IC chip is arranged in the groove, the detection sensitivity can be improved by reducing the distance between the magnet and the magnetoresistive element.

  According to a third aspect of the present invention, the biasing magnet has a substantially U-shaped cross section, and the mold resin may be in contact with the protrusion tip surface around the groove of the biasing magnet.

  In this case, the tip end surface of the protrusion faces the opposite surface of the bottom surface of the groove, and the contact location and the contact area with the mold resin increase, so that the bias magnet is more firmly fixed to the mold resin.

When the mold resin is disposed on the bottom surface of the groove of the bias magnet, a plurality of IC chips including a chip having a magnetoresistive element may be fixed on the mold resin as described in claim 4. .

  When a plurality of IC chips are fixed in a groove of a bias magnet having conductivity (for example, a rare earth magnet), the same substrate bias must be applied to the plurality of IC chips. It is necessary to unify the conductivity type (p-type / n-type).

  However, in the present invention, since the plurality of IC chips are fixed to the groove portion of the bias magnet through the non-conductive mold resin, the IC chips can be freely combined regardless of the conductivity type of the substrate material.

  Further, in the rotation detection sensor device according to any one of claims 2 to 4, as described in claim 5, the bias magnet has at least one of a convex portion and a concave portion in at least a part of the portion in contact with the mold resin. Good to be.

  In this case, in addition to the effect of the invention described in claim 1, the biasing magnet is more stably fixed to the mold resin.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
1A and 1B are diagrams showing an example of a rotation detection sensor device (hereinafter referred to as a sensor device) in the present embodiment, where FIG. 1A is a partial cross-sectional view (a cross-sectional view on the right side from an arrow), and FIG. It is sectional drawing in the AA cross section of). In addition, this sensor apparatus is applied to detection of the rotation speed and rotation direction of a subject that rotates, such as an engine rotation sensor, a crank angle sensor, a cam angle sensor, a vehicle speed sensor, and a wheel speed sensor, for example.

  As shown in FIGS. 1A and 1B, a sensor device 100 according to this embodiment includes an MRE chip 10 having a magnetoresistive element, a bias magnetic field magnet 20 (hereinafter referred to as a magnet), and the magnet 20 as an insert component. And mold resin 30 to be formed.

  The MRE chip 10 has a magnetoresistive element (not shown) formed in a predetermined shape by patterning using a material such as Ni—Co or Ni—Fe. In the present embodiment, two pairs of sensors each consisting of two magnetoresistive elements inclined by 45 degrees with respect to the central axis are arranged so that differential operation is possible. The arrangement of the magnetoresistive elements and the principle of detection of the rotational speed and direction of rotation of the rotating body by the magnetoresistive elements are disclosed in Japanese Patent Application Laid-Open No. 13-153683, etc., and will not be described here.

  In addition to the MRE chip 10, the sensor device 100 according to the present embodiment includes, for example, a CMOS chip 11 for a processing circuit for performing offset adjustment of sensor output. Like the MRE chip 10, the CMOS chip 11 is fixed to the groove portion 21 of the magnet 20 and is electrically connected to the MRE chip 10 by a bonding wire 12. The CMOS chip 11 is electrically connected to the terminal 14 by a bonding wire 13.

  The magnet 20 applies a bias magnetic field to the magnetoresistive element of the MRE chip 10. The magnet 20 in this embodiment is made of ferrite and has a groove portion 21 having a predetermined depth. Then, the MRE chip 10 and the CMOS chip 11 are directly fixed to the bottom surface of the groove portion 21 by, for example, an adhesive. That is, the IC chips 10 and 11 are bare chip mounted on the magnet 20. Therefore, the magnet 20 also serves as a case for the IC chips 10 and 11.

  Moreover, the magnet 20 has at least one of a convex part and a recessed part in at least one part of a contact part with the mold resin mentioned later. In the present embodiment, as shown in FIG. 1B, the magnet 20 has a substantially U-shaped cross section, and a convex portion 22 is formed on the lower surface facing the bottom surface of the groove portion 21.

  The mold resin 30 is made of a resin material such as PPS (polyphenylene sulfide), and is a housing that covers and protects a part of the magnet 20 excluding the groove 21 and a part of the terminal 14. In addition, as shown to Fig.1 (a), the code | symbol 30a has shown the holder part for fixation among the mold resins 30, and the code | symbol 30b has shown the connector part for external connection. In the terminal 14 described above, the other end of the connecting portion with the bonding wire 13 protrudes into the opening of the connector portion 30 b that is one end of the sensor device 100. Accordingly, the terminal 14 can output a sensor output corresponding to a change in the resistance value of the magnetoresistive element accompanying the rotation of the subject (not shown) to the outside.

  In the sensor device 100, the IC chips 10, 11 and the magnet 20 positioned on the other end side of the connector portion 30 b have a mold resin 30 around the groove portion 21 of the magnet 20 and the connection portion with the bonding wire 13 of the terminal 14. Since it is not covered by and exposed, it is covered and protected by the case 40.

  The case 40 is made of a resin material such as PPS, and is provided in a substantially cylindrical shape in the present embodiment. Then, with a predetermined range of the mold resin 30 including the IC chips 10 and 11 and the magnet 20 being accommodated in the internal space, the opening end is fixed to the mold resin 30 by, for example, welding, and the inside of the case 40 is sealed. Has been.

  Next, a method for manufacturing the sensor device 100 according to the present embodiment will be described.

  First, the magnet 20 having a predetermined shape is formed. In the present embodiment, the resin material to which the ferrite powder is added is poured into a mold having a predetermined shape and solidified, so that it has a substantially rectangular shape having grooves 21 and protrusions 22 as shown in FIGS. A magnet 20 having a letter-shaped cross section is formed. In addition, the shape of the convex part 22 will not be specifically limited if it is a shape which can exhibit an anchor effect with respect to the mold resin 30. FIG. In order to reduce the size of the sensor device 100, the magnet 20 is formed so that the side surface of the magnet 20 has a predetermined shape corresponding to the inner wall surface of the case 40, as shown in FIG.

  The magnet 20 and the terminal 14 are used as insert parts, and a mold resin 30 serving as a housing is injected in a state where both are positioned at predetermined positions of the mold. Thereby, the mold resin 30, the magnet 20, and the terminal 14 are united. At this time, the magnet 20 is disposed at a position to be the tip of the sensor device 100, and the groove portion 21 and the upper portion thereof in the magnet 20 and the connection portion and the upper portion thereof by the bonding wires 12 and 13 are exposed without being covered with the mold resin 30. Is done. Further, the mold resin 30 is formed in a predetermined shape so that at least a part thereof is positioned in contact with the inner wall surface of the case 40 when stored in a case 40 described later.

  Here, the sensor device 100 in the present embodiment is miniaturized, and as shown in FIG. 1B, the mold resin 30 is formed on the lower surface of the magnet 20 having a substantially U-shaped cross section (opposite the groove bottom surface). Surface) only. Thus, if the area where the mold resin 30 and the magnet 20 are in contact with each other is small, the magnet 20 may fall off the mold resin 30 when an impact is applied to the sensor device 100. However, as shown in FIGS. 1A and 1B, the magnet 20 has a convex portion 22, and due to the increase in the contact area with the mold resin 30 and the anchor effect of the convex portion 22, the magnet 20 is molded resin. 30 is fixed stably. That is, the magnet 20 can be prevented from falling off.

  In addition, the range of the magnet 20 which contacts the mold resin 30 and the formation position of the convex part 22 are not limited to the said example. For example, the present invention can be applied to a configuration in which all surface portions except the groove portion 21 of the magnet 20 are in contact with the mold resin 30. That is, by providing the convex portion 22 on at least a part of the surface portion in contact with the mold resin 30, the magnet 20 can be more stably fixed to the mold resin 30 than when the convex portion 22 is not provided.

  Next, after insert molding, the IC chips 10 and 11 are fixed to the groove portions 21 of the magnet 20 exposed from the mold resin 30, and the bonding wires 12 and 11 are connected between the IC chips 10 and 11 and between the CMOS chip 11 and the terminal 14. 13 for connection. In the present embodiment, the MRE chip 10 and the CMOS chip 11 are directly fixed to the bottom surface of the groove portion of the magnet 20 having a substantially U-shaped cross section using an adhesive. As described above, since the MRE chip 10 is directly mounted on the magnet 20 without any other components, the MRE chip 10 can be fixed to the magnet 20 with high accuracy. Can be reduced. That is, the detection sensitivity and detection accuracy of the sensor device 100 can be improved.

  Further, the IC chips 10 and 11 are directly fixed to the magnet 20 instead of being molded ICs. Therefore, the number of parts can be reduced (the manufacturing process can be reduced).

  Finally, in order to cover and protect a part of the exposed IC chips 10 and 11 and the terminal 14 and the connecting portions by the bonding wires 12 and 13, the above-described cases 40 are formed in a case 40 that has been processed into a predetermined shape. A predetermined range of the mold resin 30 including the portion is stored. And the opening edge part of case 40 is welded to the mold resin 30, and each said site | part is sealed airtightly. The sensor device 100 is formed by the above process.

  In the present embodiment, an example in which the magnet 20 has the convex portion 22 at the contact portion with the mold resin 30 is shown. However, the magnet 20 only needs to have at least one of the convex portion 22 and the concave portion at the contact portion with the mold resin 30. Even when the magnet 20 has a recess, the contact area with the mold resin 30 is increased, and the mold resin filled in the recess serves as an anchor, so the magnet 20 is stably fixed to the mold resin 30. . At that time, the shape of the concave portion is not particularly limited as long as the convex portion 22 can exhibit the anchor effect. Usually, the convex portion 22 and the concave portion are formed in pairs. For example, as shown in FIGS. 2 (a) and 2 (b), when a plurality of linear thin concave portions 23 are formed on the lower surface of the magnet 20 (the opposite surface of the bottom surface of the groove portion 21), the concave portions 23 and the convex portions 22 are formed as a result. The structure is formed alternately. FIG. 2 is a view showing a modification of the present embodiment, in which (a) is a cross-sectional view and (b) is a plan view of the lower surface.

  Further, in the present embodiment, an example in which only the lower surface of the magnet 20 is in contact with the mold resin 30 and the convex portion 22 and / or the concave portion 23 is provided on the lower surface is shown. However, the formation position of the convex part 22 and the concave part 23 in the magnet 20 is not particularly limited as long as it is a part in contact with the mold resin 30. For example, with respect to the magnet 20 having a substantially U-shaped cross section, as shown in FIG. 3, not only the lower surface but also the side surface portion may be formed with convex portions 22 and concave portions 23. In this case, the contact area with the mold resin 30 increases, and the mold resin 30 filled in the convex portions 22 and the concave portions 23 functions as an anchor with respect to the movement of the mold resin 30 in the vertical and horizontal directions. The magnet 20 is more stably fixed to the mold resin 30, and the magnet 20 is prevented from falling off.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. 4A and 4B are diagrams illustrating the sensor device 100 according to the present embodiment, in which FIG. 4A is a partial cross-sectional view (a cross section on the right side of the arrow), and FIG. 4B is a cross-sectional view taken along the line BB in FIG.

  Since the sensor device 100 according to the second embodiment is often in common with that according to the first embodiment, the detailed description of the common parts will be omitted below, and different parts will be described mainly.

  The second embodiment is different from the first embodiment in that the mold resin 30 is disposed on the bottom surface of the groove portion 21 of the magnet 20, and the magnet 20 is sandwiched and fixed by the mold resin 30 from both the upper and lower directions. It is a point.

  In the case of the sensor device 100 in which the MRE chip 10 is bare-chip mounted in the groove portion 21 of the magnet 20, in order to directly fix to the bottom surface of the groove portion 21, the mold resin 30 is not disposed above the groove portion 21 and the upper portion thereof during insert molding. The bottom surface of the groove 21 was exposed.

  On the other hand, in the present embodiment, as shown in FIGS. 4A and 4B, the mold resin 30 is not only disposed so as to be in contact with the lower surface of the magnet 20 (the opposite surface of the bottom surface of the groove portion 21). Also, it is arranged on the bottom surface of the groove portion 21 which is the opposite surface of the lower surface. That is, the magnet 20 is sandwiched and fixed by the mold resin 30 from both the upper and lower directions. Therefore, since the magnet 20 is stably fixed to the mold resin 30, it is possible to prevent the magnet 20 from falling off the mold resin 30.

  In the manufacturing method shown in the first embodiment, such a sensor device 100 is formed by insert-molding a mold so that the mold resin 30 is disposed on the bottom surface of the groove portion 21 of the magnet 20. It can be formed by fixing the IC chips 10 and 11 on the mold resin 30 disposed on the bottom surface.

  If the MRE chip 10 is disposed in the groove portion 21, a sensor made of a magnetoresistive element can be disposed close to the magnet 20, so that the detection sensitivity of the sensor device 100 can be improved. Therefore, the thickness of the mold resin 30 disposed on the bottom surface of the groove portion 21 is such that the upper surface of the MRE chip 10 fixed on the mold resin 30 remains in the groove portion 21 of the magnet 20. Is preferred.

  When the magnet 20 is made of a non-conductive material such as ferrite, a plurality of IC chips including the MRE chip 10 are used regardless of the conductivity type (p-type / n-type) of the substrate material constituting the IC chip. It can be fixed directly to the magnet 20. However, when a plurality of IC chips are directly fixed to the magnet 20 made of a conductive material such as a rare earth magnet, the same substrate bias must be applied to the plurality of IC chips. It is necessary to unify the conductivity type (p-type / n-type).

  On the other hand, in the sensor device 100 of the present embodiment, a plurality of IC chips including the MRE chip 10 are fixed to the groove portion 21 of the magnet 20 via the non-conductive mold resin 30. Therefore, regardless of the conductivity type of the substrate material of the IC chip, a plurality of IC chips can be freely combined and mounted on the magnet 20 regardless of the conductivity type of the substrate material of the IC chip. .

  Moreover, in this embodiment, the example in which the mold resin 30 is arrange | positioned so that the lower surface of the magnet 20 and the bottom face of the groove part 21 may be shown was shown. However, the surface facing the lower surface of the magnet 20 is not limited to the bottom surface of the groove 21. For example, as shown in this embodiment, when the magnet 20 has a substantially U-shaped cross section (when there is a gap between the tip of the protrusion and the case 40 and the mold resin 30 can be filled). The tip end surface of the protrusion around the groove 21 is also opposed to the lower surface of the magnet 20. Therefore, as shown in FIG. 5, when the mold resin 30 is disposed so as to contact the tip end surface of the protrusion, the contact area between the magnet 20 and the mold resin 30 increases, and the magnet 20 and the mold that are in the opposing positional relationship with each other are molded. Since the number of contact points with the resin 30 increases, the magnet 20 can be stably fixed by the mold resin 30. That is, the magnet 20 can be prevented from falling off.

  Further, in FIG. 5, the magnet 20 has a convex portion 22 on the surface in contact with the mold resin 30 (the lower surface in FIG. 5). In this case, since the anchor effect (and contact area increase) of the convex portion 22 is further added to the above-described effect, it is more effective for preventing the magnet 20 from falling off. The configuration in which the concave portion 23 is provided instead of the convex portion 22 is the same. Further, the convex portion 22 and / or the concave portion 23 are provided in a portion that contacts the mold resin 30 of the magnet 20. Therefore, as shown in the present embodiment, when the mold resin 30 is disposed on the bottom surface of the groove portion 21 of the magnet 20, the bottom surface of the groove portion 21 may have a convex portion 22 and / or a concave portion 23. . However, it is necessary to pay attention to the contact area with the IC chips 10 and 11 and the arrangement position of the MRE chip 10 (height of the convex portion 22).

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made.

  In the present embodiment, the bottom surface of the groove 21 and the lower surface of the magnet 20 are in contact with the mold resin 30, and the magnet 20 is sandwiched and fixed by the mold resin 30. However, the configuration in which the magnet 20 is sandwiched and fixed between the mold resins 30 is not limited to the above example. For example, it is good also as a structure which arrange | positions the mold resin 30 on the both sides | surfaces of the magnet 20, and pinches | interposes the magnet 20 with the mold resin 30 from both right and left directions. Further, the mold resin 30 is fixed from both the upper and lower directions, and the mold resin 30 is not disposed on the bottom surface of the groove portion 21, so that the protrusion tip surface around the groove portion 21 and the lower surface of the magnet 20 shown in FIG. A configuration may be adopted in which the mold resin 30 is disposed and the magnet 20 is sandwiched and fixed from both the upper and lower directions.

  In the present embodiment, an example is shown in which the MRE chip 10 and the CMOS chip 11 are fixed to the magnet 20 as IC chips. However, the IC chip fixed to the magnet 20 is not limited to the above example. It is sufficient that the MRE chip 10 is fixed at least.

It is a figure which shows schematic structure of the rotation detection sensor apparatus in 1st Embodiment, (a) is a fragmentary sectional view, (b) is sectional drawing in the AA cross section of (a). It is a figure which shows the modification of a magnet, (a) is sectional drawing, (b) is a top view of a lower surface. It is sectional drawing which shows the modification of a magnet. It is a figure which shows schematic structure of the rotation detection sensor apparatus in 2nd Embodiment, (a) is a fragmentary sectional view, (b) is sectional drawing in the BB cross section of (a). It is sectional drawing which shows a modification.

Explanation of symbols

10 ... MRE chip (IC chip)
20 ... Bias magnet (magnet)
21 ... groove 22 ... convex 23 ... concave 30 ... mold resin 40 ... case 100 ... rotation detection sensor device (sensor device)

Claims (5)

A biasing magnet having a groove ,
An IC chip including a chip having a magnetoresistive element ,
A rotation detection sensor in which the IC chip in a bare chip state is directly fixed to the bottom surface of the groove after a part of the biasing magnet as an insert part is coated by injection of mold resin so that the groove is exposed. A device ,
The rotation detection sensor device, wherein the bias magnet has at least one of a convex portion and a concave portion in at least a part of a portion in contact with the mold resin. A biasing magnet having a groove ,
An IC chip including a chip having a magnetoresistive element ,
Wherein such groove is exposed, after a part of the bias magnet as the insert part is coated by means of injection of the molding resin, the rotation detecting sensor device the IC chip of the bare chip state in said groove is disposed Because
The mold resin is in contact with the groove bottom surface of the bias magnet and the opposing surface of the groove bottom surface ;
The rotation detection sensor device according to claim 1, wherein the IC chip is fixed to the bottom surface of the groove portion through the mold resin in a state where the IC chip is disposed in the groove portion . The biasing magnet has a substantially U-shaped cross section,
The rotation detection sensor device according to claim 2, wherein the mold resin is in contact with a protrusion front end surface around a groove portion of the bias magnet. 4. The rotation detection sensor device according to claim 2 , wherein a plurality of the IC chips are fixed to the bottom surface of the groove portion of the bias magnet via the mold resin. 5.   5. The rotation detection sensor device according to claim 2, wherein the bias magnet has at least one of a convex portion and a concave portion in at least a part of a portion in contact with the mold resin.

Images