JP4617762B2 - Method for manufacturing rotation detection device - Google Patents

Description

  The present invention relates to a method of manufacturing a rotation detection device that detects a rotation mode of a rotor by sensing a change in magnetic vector as a change in resistance value of a magnetoresistive element.

  Conventionally, for example, a device described in Patent Document 1 is known as a rotation detection device that performs rotation detection using the resistance value change of the magnetoresistive element. FIG. 7 shows a planar structure of a rotation detection device that is generally employed conventionally as a rotation detection device such as a crank angle sensor of an engine, including the rotation detection device described in Patent Document 1.

  As shown in FIG. 7, this rotation detection device includes a sensor chip 11 including a magnetoresistive element pair 1 composed of magnetoresistive elements MRE1 and MRE2 and a magnetoresistive element pair 2 composed of magnetoresistive elements MRE3 and MRE4. It arrange | positions so that the rotor RT which is a to-be-detected object may be opposed. The sensor chip 11 is integrated with the processing circuit, and is integrally resin-molded by a mold member 12. Specifically, the sensor chip 11 is mounted on one end of a lead frame (not shown) inside the mold member 12, and terminals such as a power terminal T1, an output terminal T2, and a GND (ground) terminal T3 are drawn from the other end. It has a structure.

  In the vicinity of the sensor chip 11, a bias magnet 13 that applies a bias magnetic field to the magnetoresistive element pairs 1 and 2 is disposed so as to surround the mold member 12. That is, as shown in detail in FIG. 8, the bias magnet 13 is formed in a hollow cylindrical shape having a hollow portion 14 in the longitudinal direction, and the mold member 12 including the sensor chip 11 is accommodated in the hollow portion 14. And fixed in place with an adhesive or the like. As the bias magnet 13, a magnet obtained by mixing and solidifying magnetic powder and resin is generally used because of its moldability.

In the rotation detection device having such a configuration, a change in the magnetic vector generated in cooperation with the bias magnetic field when the rotor RT rotates is detected as a change in the resistance value of each of the magnetoresistive elements MRE1 to MRE4. A corresponding electrical signal is output from the sensor chip 11. Incidentally, in this rotation detection device, both the magnetoresistive elements MRE1 and MRE2 constituting the magnetoresistive element pair 1 and the magnetoresistive elements MRE3 and MRE4 constituting the magnetoresistive element pair 2 are electrically half-bridge circuits. The change in each midpoint potential is applied to the processing circuit, and after various processing such as differential amplification and binarization, the change is taken out from the output terminal T2.
JP 2002-357454 A

  By the way, the bias magnet used in the above-described rotation detection device can obtain desired characteristics (magnetic flux density, magnetic flux opening angle, etc.) according to the shape of the rotor to be detected, the specification of the rotation detection device, and the like. Molding conditions such as the shape and material are set, and molding is performed based on the set conditions. Then, after the bias magnet is molded in this way, it is measured whether or not the molded bias magnet satisfies the desired characteristics described above. And the mold member 12 are assembled together. In order to measure whether or not the desired characteristics are satisfied, for example, an inspection chip is inserted into the hollow portion 14 of the bias magnet 13 to measure the opening angle of the magnetic flux, or the hollow portion of the bias magnet 13 is measured. This is performed by inserting a probe into the magnet 14 and measuring the magnetic flux density.

  However, even if the above-described forming conditions are set and the bias magnet is formed, the magnetic field characteristics exhibited by the formed bias magnet may deviate from the desired characteristics. In recent years, with the miniaturization of the rotor and the high accuracy of the rotation detection device, the bias magnet itself is required to have high accuracy, and the reduction of the tolerance is strongly desired. Such a situation is one of the factors that reduce the yield in manufacturing the rotation detecting device.

  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 rotation detection device that can suppress a decrease in yield due to the forming accuracy of a bias magnet.

To achieve these objectives, the invention described in claim 1, the bias magnet in the longitudinal direction after the molding of the bias magnet configured in a hollow cylindrical shape with a hollow portion, a magnetic resistance element housed in the hollow portion While measuring the characteristics of the bias magnetic field applied by the sensor, trimming is performed by reducing the length in the longitudinal direction of the bias magnet until the magnetic field characteristics become a desired characteristic, and the sensor chip is integrated with the trimmed bias magnet. I decided to assemble it.

  According to such a manufacturing method, even when a bias magnet having a magnetic field characteristic deviated from a desired characteristic is formed, it is possible to match the desired characteristic through trimming of the bias magnet. For this reason, also in manufacture of a rotation detection apparatus, the fall of the yield resulting from the shaping | molding precision of a bias magnet can be suppressed suitably.

Then , if the measurement of the magnetic field characteristic is performed as measurement of the opening angle and magnetic flux density of the magnetic flux emitted from the bias magnet, the opening angle of the magnetic flux which is an important characteristic in determining the specifications of the rotation detection device In addition, a bias magnet that exhibits good characteristics with respect to the magnetic flux density, which is also one of important characteristics, can be obtained accurately. If the magnetic flux density of the bias magnet is measured based on the output of the probe inserted into the bias magnet, the magnetic flux density of the bias magnet is accurately and smoothly measured based on the output of the probe. This makes it possible to perform accurate trimming.

Furthermore, as according to the invention described in claim 2, the measurement of the opening angle of the magnetic flux emanating from the biasing magnet, the output of the testing chip inserted into the bias magnet, a variety for the same testing chip if it is done by collating the output data opening angle the testing chip that has been collected in advance by applying a magnetic field of the magnetic flux, based on the output of the testing chip of this magnetic flux of the bias magnet The opening angle can also be measured accurately and smoothly , thereby enabling more accurate trimming. Further, in the detection method of the rotation detection device according to claim 1 or 2, according to the invention of claim 3, the shape of the rotor rotating in the vicinity of the sensor chip and the specification of the rotation detection device According to at least one of them, the opening angle of the magnetic flux and the magnetic flux density, which are the important characteristics, are adjusted. As a result, the opening angle and magnetic flux density of the magnetic flux, which are the important characteristics, can be adjusted to more suitable values.

In addition, according to the invention described in claim 4 , these manufacturing methods are for manufacturing a rotation detection device of the type using a resin-molded sensor chip in advance, that is, a rotation detection device as exemplified in the conventional example. It is particularly effective when applied to the method.

  Hereinafter, an embodiment of a method for manufacturing a rotation detection device according to the present invention will be described with reference to FIGS. Since the rotation detection device manufactured by this method is basically the same as the conventional rotation detection device described above, the same components are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 1 shows a manufacturing process flow from forming a bias magnet to actually completing a rotation detecting device. As shown in FIG. 1, first, in step S1, the bias magnet 13 (FIG. 8) is formed. As described above, the bias magnet 13 is formed in advance by aiming at a desired magnetic field characteristic according to the shape of the rotor, the specification of the rotation detection device, and the like, and in this embodiment, a desired magnetic flux opening angle and magnetic flux density. The shape, material, etc. are set and molded. The bias magnet 13 is formed by, for example, solidifying a magnet material obtained by mixing magnetic powder and resin using a mold.

Next, in step S2, the magnetic flux opening angle and magnetic flux density of the bias magnet 13 formed in the previous step S1 are measured in the following manner.
The measurement of the opening angle of the magnetic flux is performed based on a signal output from the inspection chip by inserting the inspection chip into the hollow portion 14 of the molded bias magnet 13. Specifically, as shown in FIG. 2, a magnetoresistive element pair A1 composed of magnetoresistive elements MREa and MREb and a magnetoresistive element pair A2 composed of magnetoresistive elements MREc and MREd corresponding to the magnetoresistive element pairs 1 and 2 are provided. Using the inspection chip C, the inspection chip C is inserted into the hollow portion 14 of the bias magnet 13. Then, the opening angle of the magnetic flux at the position where the magnetoresistive element pairs 1 and 2 are actually arranged is measured based on the voltage values Va and Vb indicated by the magnetoresistive element pairs A1 and A2, respectively. In this measurement, a magnetic field having various magnetic flux opening angles is applied to the magnetoresistive element pairs A1 and A2 in advance, and a large number of data of voltage values Va and Vb shown for each magnetic field are collected. The measurement is performed by comparing the measured voltage values Va and Vb with the collected data.

  On the other hand, the measurement of the magnetic flux density is performed by inserting a probe for measuring the magnetic flux density into the hollow portion 14 of the molded bias magnet 13 and actually measuring the magnetic flux density at the position where the magnetoresistive element pairs 1 and 2 are arranged. This is done by measuring The magnetic flux density is measured using a known probe, and the magnetic flux density is measured based on a signal output from the probe.

  Next, in step S3, it is determined whether or not the magnetic flux opening angle and magnetic flux density measured in the previous step S2 are the desired magnetic flux opening angle and magnetic flux density. When it is determined that the magnetic flux opening angle and the magnetic flux density measured in the previous step S2 are the desired magnetic flux opening angle and magnetic flux density, the process proceeds to step S4. In step S4, the bias magnet 13 and the molded member 12 in which the sensor chip 11 is actually molded are assembled together.

  On the other hand, when it is determined that the magnetic flux opening angle and magnetic flux density measured in the previous step S2 are not the desired magnetic flux opening angle and magnetic flux density, the process proceeds to step S5. In step S5, a part of the bias magnet 13 is trimmed until the desired magnetic flux opening angle and magnetic flux density are obtained. This trimming is performed by laser trimming, for example.

  Here, the relationship between the trimming of the bias magnet 13 and the opening angle of the magnetic flux and the magnetic flux density changed thereby will be described. In this embodiment, as shown in FIG. 3, the bias magnet 13 is trimmed in the length direction (the hatched portion in FIG. 3 is a trimmed portion).

  FIG. 4 shows the opening angle and magnetic flux density of the magnetic flux that change due to this trimming. As shown in FIG. 4, the opening angle of the magnetic flux becomes smaller as the trimming amount of the bias magnet 13 is larger, that is, as the length of the bias magnet 13 is shorter. This is because the distance between the N pole and the S pole is shortened by shortening the bias magnet 13, and the magnetic flux from the N pole to the S pole acts in the closing direction rather than the opening direction. For this reason, it is possible to suppress the opening angle of the magnetic flux to a desired opening angle of the magnetic flux by adjusting the trimming amount in the length direction of the bias magnet 13. On the other hand, the magnetic flux density increases as the amount of trimming of the bias magnet 13 increases, that is, as the length of the bias magnet 13 decreases. For this reason, it is possible to adjust the magnetic flux density to a desired magnetic flux density by adjusting the trimming amount in the length direction of the bias magnet 13.

  Therefore, in the present embodiment, in the step S5, the length of the bias magnet 13 is adjusted by trimming, and the magnetic flux opening angle and the magnetic flux density of the bias magnet 13 are adjusted. However, since the opening angle of magnetic flux and the magnetic flux density are in a contradictory relationship as described above, it may be difficult to adjust both to a suitable value only with the length of the bias magnet 13. For this reason, they are weighed in accordance with the shape of the rotor to be detected, the specification of the rotation detection device, etc., and adjusted appropriately to a suitable value.

  The steps S2, S3 and S5 are repeated, and if it is determined in step S3 that the magnetic flux opening angle and magnetic flux density have reached the desired magnetic flux opening angle and magnetic flux density, the process proceeds to step S4. Then, the bias magnet 13 with the magnetic flux opening angle adjusted and the mold member 12 are assembled together.

  In step S6, the mold member 12 and the bias magnet 13 assembled together in the previous step S4 and the main body case (not shown) are integrally formed to manufacture the rotation detecting device.

According to the embodiment described above, the effects listed below can be obtained.
(1) While measuring the magnetic flux opening angle and magnetic flux density of the formed bias magnet 13, trimming was performed until they reached the desired magnetic flux opening angle and magnetic flux density. For this reason, even when the bias magnet 13 showing characteristics deviating from the desired magnetic flux opening angle and magnetic flux density is formed, the desired magnetic flux opening angle and magnetic flux density are adjusted through trimming of the bias magnet 13. Can be included. For this reason, generation | occurrence | production of what is called inferior goods will be suppressed, and also at the time of manufacture of a rotation detection apparatus, the fall of the yield resulting from the shaping | molding precision of the bias magnet 13 can be suppressed suitably.

  (2) Trimming the bias magnet 13 while measuring the opening angle and magnetic flux density of the magnetic flux at the position where the magnetoresistive element pairs 1 and 2 are actually arranged using the inspection chip C and the probe. did. Therefore, the opening angle and magnetic flux density of the magnetic flux can be accurately measured, and the opening angle and magnetic flux density of the magnetic flux can be accurately adjusted to the desired one by trimming performed based on the measurement result. become able to.

  (3) When measuring the opening angle of the magnetic flux using the inspection chip C, a magnetic field having various opening angles of the magnetic flux is applied to the magnetoresistive element pairs A1 and A2 in advance, and the voltage value Va, shown for each magnetic field, Vb data was collected in advance and the magnetic flux opening angle was measured with reference to the data. For this reason, process S2 can be performed smoothly.

In addition, the said embodiment can also be changed and implemented as follows.
In the above embodiment, the bias magnet 13 is trimmed so as to shorten the length of the bias magnet 13 and the magnetic flux opening angle and the magnetic flux density are adjusted. For example, FIGS. The bias magnet 13 may be trimmed in each manner as shown in FIG. In these drawings, the hatched portion is the trimming portion. That is, as shown in FIG. 5A, trimming is performed from the upper surface to the side surface of the bias magnet 13, or a groove such as a V-shaped groove is formed in the upper surface portion of the bias magnet 13 as shown in FIG. Trimming may be performed in a manner, or trimming may be performed in a manner in which the diameter of the bias magnet 13 is reduced as illustrated in FIG. As described above, if trimming is performed while measuring the magnetic flux opening angle and magnetic flux density of the bias magnet 13, the magnetic field characteristics such as the magnetic flux opening angle and magnetic flux density of the bias magnet 13 are desired regardless of the trimming mode. It is possible to adjust to the characteristic as described above, and thereby, an effect substantially equivalent to that of the above embodiment can be obtained.

  In the above embodiment, the present invention is applied in the manufacture of the rotation detection device including the bias magnet 13 that surrounds the mold member 12, but the rotation shown in FIGS. 6 (a) and 6 (b). The present invention may be applied when manufacturing the detection device. In the rotation detection device shown in FIG. 6, a sensor chip 21a and a processing circuit chip 21b and a bias magnet 22 for generating a bias magnetic field are respectively assembled on the front and back of a lead frame 23, and they are integrally resin-molded by a molding member 24. Configured. The sensor chip 21a includes the magnetoresistive element pairs 1 and 2 configured by the magnetoresistive elements MRE1 to MRE4 as in the above embodiment. The processing circuit chip 21b is electrically connected to the sensor chip 21a via the wiring 25a, and performs signal processing such as differential amplification and binarization of an electric signal output from the sensor chip 21a. Is. The bias magnet 22 has a rectangular parallelepiped shape, and the side close to the sensor chip 21a is magnetized with an N pole and the opposite side is magnetized with an S pole. In this rotation detection device, after the signal from the sensor chip 21a is subjected to processing such as differential amplification and binarization in the processing circuit chip 21b, the signal is connected to the terminals Ta and Tb via the wiring 25b. It comes to be taken out from. In this rotation detection device, the bias magnet 22 has a rectangular parallelepiped shape unlike the above embodiment, but the opening angle and magnetic flux density of the magnetic flux can be adjusted by trimming. That is, the present invention can also be applied to this type of rotation detection device, and the same effects as those of the above embodiment can be obtained. Although not shown in the drawings, the present invention can be similarly applied to, for example, a rotation detection device in which a sensor chip is directly attached to a U-shaped bias magnet.

  In the above embodiment, the inspection chip C having the magnetoresistive element pairs A1 and A2 is used as the inspection chip for measuring the opening angle of the magnetic flux of the bias magnet 13, but the magnetoresistive element pairs A1 and A2 are used as the inspection chip C1. Instead, for example, the opening angle of the magnetic flux may be measured using an inspection chip having a Hall element. In other words, as long as the opening angle of the magnetic flux at the position where the magnetoresistive element pairs 1 and 2 are arranged can be measured, a chip having another configuration may be adopted. Further, it is not always necessary to measure the opening angle of the magnetic flux at the position where the magnetoresistive element pairs 1 and 2 are arranged, and the opening angle of the magnetic flux at the above position is measured by measuring the opening angle of the magnetic flux at a position different from them. The angle may be estimated. The same applies to the measurement of the magnetic flux density.

  In the above embodiment, the magnetic flux opening angle and magnetic flux density are adjusted by trimming as the magnetic field characteristics of the bias magnet 13, but other magnetic field characteristics can also be adjusted by trimming. Further, when the dimension of the simply formed bias magnet is different from the design dimension, the design dimension can be adjusted by trimming.

The flowchart which shows the manufacturing process about one Embodiment of the manufacturing method of the rotation detection apparatus concerning this invention. The circuit diagram which shows a part of the structure about the test | inspection chip | tip used when measuring the opening angle of the magnetic flux of the bias magnet used for manufacture of the rotation detection apparatus of the embodiment. The perspective view which shows the trimming aspect about the bias magnet used for manufacture of the rotation detection apparatus of the embodiment. The graph which shows the relationship between the length of the bias magnet used for manufacture of the rotation detection apparatus of the embodiment, magnetic flux opening angle, and magnetic flux density. (A)-(c) is a perspective view which shows the various trimming aspects of a bias magnet as a modification of the embodiment. (A) is a side view which shows the internal structure of another type of rotation detection apparatus as a modification of the said embodiment. (B) is a top view which shows the internal structure of the rotation detection apparatus shown to (a). The figure which shows the detection aspect of the rotation about the conventional rotation detection apparatus. The perspective view which shows a part of the structure about the conventional rotation detection apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,2 ... Magnetoresistive element pair, 11 ... Sensor chip, 12 ... Mold member, 13 ... Bias magnet, 14 ... Hollow part, 21a ... Sensor chip, 21b ... Processing circuit chip, 22 ... Bias magnet, 23 ... Lead frame, 24 ... mold member, 25a ... wiring, 25b ... wiring, C ... chip for inspection, MRE1 to MRE4 ... magnetic resistance element, T1 ... power supply terminal, T2 ... output terminal, T3 ... grounding (GND) terminal, RT ... rotor, Ta , Tb... Terminals.

Claims (4)

A bias magnet that is configured in a hollow cylindrical shape with a hollow portion in the longitudinal direction, and a sensor chip having a magnetoresistive element that is accommodated in the hollow portion bias magnetic field by the bias magnet is applied, the sensor chip For detecting a rotation mode of the rotor by detecting a change in the magnetic vector generated in cooperation with the bias magnetic field as a change in the resistance value of the magnetoresistive element when the rotor rotates in the vicinity of the rotor Because
After forming the bias magnet, an inspection chip is inserted into the hollow portion to measure the opening angle of the magnetic flux emitted from the bias magnet at the position where the magnetoresistive element is disposed. While measuring the magnetic flux density at the position where the magnetoresistive element emitted from the bias magnet is inserted by inserting a probe for measuring the magnetic flux density, the opening angle of the magnetic flux and the value of the magnetic flux density to be measured are desired. And a step of reducing the length of the bias magnet in the longitudinal direction by trimming until the value reaches the value of the above, and a step of assembling the sensor chip integrally with the trimmed bias magnet. . The magnetic flux opening angle is measured in advance by applying a signal output from the inspection chip inserted into the hollow portion and a magnetic field having various magnetic flux opening angles to the inspection chip. The method of manufacturing a rotation detecting device according to claim 1, wherein the rotation detecting device is performed by comparing output data of the inspection chip with respect to each of the magnetic fields . Method of manufacturing a rotation detecting device according to claim 1 or 2 that adjust the desired value in accordance with at least one of the shape and specifications of the rotation detecting device of the rotor. Method of manufacturing a rotation detecting device according to claim 1 to 3 any one of Ru with those previously resin mold as the sensor chip.

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