JP2018112537A - Integrated magnetic sensor and lead frame used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an integrated magnetic sensor that has a fast detection response speed, a high manufacturing yield, and high reliability, and a lead frame used therefor.SOLUTION: An IC chip mount part 20 of a lead frame 10 is formed with a base 21 and one or more horn-like parts 22, 23 projecting at a right angle from the base 21. A total length of the base 21 and horn-like parts 22, 23 is determined according to a length of a side corresponding to the IC chip 40, and a magnetoelectric conversion element arrangement part 44 of the IC chip 40 is arranged between the horn-like parts 22, 23.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a magnetic sensor and a lead frame used therefor, and more particularly to an IC (semiconductor integrated circuit) magnetic sensor that detects a current flowing through a conductor and outputs a corresponding electrical signal, and a lead frame used therefor.

  In order to detect the current flowing through the conductor in a non-contact manner, the magnetic field generated by this current is detected by a Hall effect element (hereinafter simply referred to as a Hall element) which is a magnetoelectric conversion element (hereinafter simply referred to as a magnetoelectric conversion element). Various magnetic sensors that output electrical signals have been developed and are commercially available.

  Such a magnetic sensor is used with a large number of signals or control conductors in an electronic device such as a vehicle or an electronic application device, and is used to detect a current (input current) flowing through these conductors. It is generally desirable for these devices to be small, light and inexpensive. In addition, the detection output of these magnetoelectric conversion elements is weak and changes depending on the ambient temperature and other conditions. Therefore, one or more magnetoelectric conversion elements, an amplifier for the detection output, a detection output correction circuit, etc. It is desirable to make an IC magnetic sensor integrated or integrated on a straight) into an IC chip.

  In general, a large number of ICs are simultaneously formed on a semiconductor substrate by a well-known technique, joined to a lead frame made of conductive metal, and divided into individual pieces after predetermined electrical connection to form an IC magnetic sensor. The For this purpose, the lead frame has an IC chip mount portion that supports the IC chip and a plurality of lead portions (terminal portions). The terminals (or connection pads) of the IC chip and the lead portions of the lead frame are generally electrically connected by a wire bonding technique using a thin gold wire.

  In order to make a magnetic sensor into an IC, an IC chip in which various electronic circuits such as a magnetoelectric conversion element and an amplifier circuit are integrally formed is bonded (or bonded) to an IC pad mount portion of a lead frame with an appropriate adhesive. Provide necessary physical support and heat dissipation. Further, the plurality of connection pads on the IC chip and the plurality of lead portions of the lead frame are electrically connected by the wire bonding described above. Finally, except for the connection part with the outside, the whole is covered and protected with an epoxy resin or the like. Here, the IC magnetic sensor refers to a magnetic detection device including an IC chip including a magnetoelectric conversion element and a lead frame and manufactured as described above.

  Such IC magnetic sensors are commercially available and disclosed in several patent documents. An IC chip mount for the lead frame due to a change in the magnetic field to be measured by providing an elongated slit extending substantially over the entire IC chip mount portion that is a support portion of the lead frame for joining the IC chip to a lead frame having a sufficient area. An IC lead frame is disclosed that prevents measurement errors due to eddy currents generated in the section (see, for example, Patent Document 1 and Patent Document 2).

  In addition, a first slot is formed from one side of the lead frame having a large area on which the IC chip is placed to the other side, and a second slot perpendicular to the first slot is formed from the end of the first slot. An IC magnetic sensor using a lead frame is also disclosed (see, for example, Patent Document 3).

US Pat. No. 6,853,178 US Pat. No. 6,922,048 Japanese Patent No. 5676635

  In order to obtain an IC magnetic sensor with a small detection error and a good response speed of magnetic detection, the conductor should be removed or moved away from the vicinity of the magnetoelectric transducer as much as possible in order to reduce the influence of the eddy current. It turns out to be desirable. In other words, it is desirable that the conductive portion of the lead frame does not exist in the vicinity of the magnetoelectric conversion element in the IC chip mount region.

  However, if the IC chip is not accurately placed on the lead frame, that is, not bonded and fixed, the wire bonding operation, which is a subsequent process, becomes difficult, and the electrical connection between the lead frame and the IC chip is defective. Insufficient bonding strength results in reduced product yield and reliability.

  The present invention has been made in view of the above-described various problems of the prior art, and an object of the present invention is to provide an IC magnetic sensor that solves or reduces these problems and a lead frame used therefor.

  In order to solve the above-described problems and achieve the above-described object, the IC-integrated magnetic sensor of the present invention employs the following characteristic configuration. That is, an IC magnetic sensor for joining a rectangular IC chip having at least one magnetoelectric conversion element and a wire bonding area to an IC chip mounting portion of a lead frame, and the lead frame is mounted on the wire bonding area of the IC chip. The IC chip has a base portion that protrudes from the base portion at a right angle so that the IC chip does not overlap the square portion of the lead frame when the lead frame is viewed in plan. It is characterized by being arranged.

  Here, the square portion of the lead frame is formed symmetrically with respect to the base portion. In addition, the length of the corner portion of the lead frame is determined by the total size of the base portion and the corner portion of the lead frame according to the dimension of the corresponding side of the IC chip mounted on the IC chip mounting portion of the lead frame. Is done. The magnetoelectric conversion element of the IC chip is disposed between the two square portions of the lead frame. The plurality of magnetoelectric conversion elements are arranged on both sides of the square portion of the lead frame.

The lead frame used in the IC magnetic sensor of the present invention adopts the following characteristic configuration. That is, a lead frame used for an IC magnetic sensor having a substantially rectangular IC chip including at least one magnetoelectric conversion element, and a base portion on which a connection pad area of the IC chip is disposed;

At least one square portion projecting perpendicularly from the base portion, and the length of the square portion is the total dimension of the base portion and the square portion of the lead frame placed on the IC chip mount portion of the lead frame. This is determined according to the dimension of the corresponding side of the IC chip.

  Here, the square portion of the lead frame is formed symmetrically with respect to the base portion. A plurality of square portions of the lead frame are formed parallel to each other. Further, the lead frame has a single square portion, and the magneto-electric conversion elements of the IC chip are arranged on both sides thereof.

  In the IC-integrated magnetic sensor according to the present invention, since the lead frame has a base portion and an elongated rectangular portion projecting at right angles to the base portion, the conductor disposed in the vicinity of the magnetoelectric conversion element of the IC chip is the smallest, so eddy current The response speed of magnetic detection is greatly improved by suppressing the adverse effects caused by. In addition, the square part of the lead frame is symmetrical with respect to the base and has a length corresponding to the dimension of the corresponding side of the IC chip, so that it is stably mounted on the lead frame with accurate parallelism and sufficient strength. In addition, post-processing such as wire bonding can be performed with high reliability, and high yield, reliability, and cost reduction of the magnetic sensor with IC can be realized. Furthermore, it is possible to deal with an IC chip having a single or a plurality of magnetoelectric conversion elements as required.

  In addition, by using the lead frame of the present invention, the bonding accuracy and bonding force of the IC chip to the lead frame can be maintained and the subsequent processes such as wire bonding can be executed reliably. It is possible to maintain high product yield and reliability by the process, and it is possible to reduce the price.

  Next, with reference to the attached drawings, the configuration and operation effects of the IC magnetic sensor according to the present invention and the lead frame used therein will be described in detail.

It is a top view which shows the 1st implementation mobile of the lead frame used for the IC-ized magnetic sensor by this invention. It is a top view which shows 2nd Embodiment of the lead frame used for the IC-ized magnetic sensor by this invention. It is explanatory drawing of the specific example which applies the IC-ized magnetic sensor of this invention. It is explanatory drawing of the IC-ized magnetic sensor by this invention arrange | positioned and used in the space | gap of the magnetic core (simply called a core) in FIG. It is explanatory drawing of the eddy current which arises in a conductor, when conductors, such as a lead frame, and a magnetic force line which changes are linked. The prior art example of the lead frame for IC is shown, (a) is a top view, (b) is a top view which shows the other example of an IC chip mount part. It is a top view which shows the other conventional example of the lead frame used for an IC-ized magnetic sensor.

  Next, an embodiment of an IC magnetic sensor according to the present invention and a lead frame used therein will be described in detail with reference to the accompanying drawings. It should be noted that the embodiments shown here are merely examples of the present invention and do not limit the present invention, and various modifications and changes can be made according to a specific application.

  First, FIG. 3 is an explanatory view showing an application example of the IC magnetic sensor according to the present invention. In this application example, an IC magnetic sensor 100 including a magnetoelectric conversion element (for example, a Hall element) is disposed in a gap 112 (see FIG. 4) formed in a core 110 through which a conductor 120 through which an input current flows is passed. Yes. The core 110 collects a magnetic field generated around the conductor 120 when an input current flows. The IC magnetic sensor 100 is supplied with a power source (not shown) necessary for its operation. Since the detection output of the IC magnetic sensor 100 is generally weak, it is amplified to an appropriate amplitude by the amplifier 130 and output between the output terminal 140 and the ground terminal 141. The amplifier 130 is preferably formed integrally with the IC magnetic sensor 100, that is, integrated with the IC.

  Next, FIG. 4 is an enlarged view of a part of the core 110 on which the IC magnetic sensor 100 of FIG. 3 is arranged. The IC magnetic sensor 100 disposed in the minute gap 112 formed in the core 110 is fixed to the conductive lead frame 102 with an appropriate adhesive or the like. As will be described later, the IC magnetic sensor 100 is bonded to a conductive lead frame 102 and is entirely covered with an epoxy resin or the like except for a connection portion (lead terminal portion) to the outside.

  Magnetic lines of force are generated in the core 110 and the air gap 112 in FIG. 4 by the input current flowing through the conductor 120. When the magnetic force lines 103 change, an eddy current 104 is inevitably generated around the magnetic force lines 103 in the lead frame 102, which is a conductor constituting the IC magnetic sensor 100, as shown in FIG. Since the eddy current 104 has an action of canceling out the original magnetic field lines (that is, magnetic field lines generated around the conductor 120 by the input current), it is desirable for the integrated magnetic sensor 100 to minimize this.

  Here, in order to help understanding of the problems and operational effects of the present invention, first, with reference to FIGS. 6 and 7, the conventional technique for reducing the eddy current generated in the conductor of the IC chip mounting portion of the lead frame 102 will be described. I will explain.

  FIG. 6 is a plan view of a conventional lead frame disclosed in Patent Document 1 and Patent Document 2 described above. A lead frame unit 200 shown in FIG. 6A includes a substantially square chip mount pad 201 that supports an IC chip including a magnetic sensor and the like, and a plurality of lead frame segments arranged and formed around the chip mount pad 201. The chip mount pad 201 is formed with an extremely thin slit 205 of 0.01 to 0.5 mm so as to substantially traverse the entire length. The slit 205 suppresses the eddy current described above with reference to FIG. On the other hand, FIG. 6B shows a chip mount pad of a conventional lead frame in which a slit 302 is formed from the vicinity of one side 303 to the vicinity of the opposite side 304 for the same purpose as in FIG. 300 is disclosed.

  FIG. 7 is a plan view of the conductive lead frame 502 of the conventional magnetic sensor 500 disclosed in Patent Document 3 described above. The lead frame 502 is formed with a first slot 510 from one side to the other side and a second slot 520 continuous from the end of the first slot 510 in order to reduce the above-described eddy current. Here, the central axis 511 of the first slot 510 and the central axis 521 of the second slot 520 are orthogonal to each other. The IC chip 530 is arranged in alignment with these slots 510 and 520.

  However, in the lead frames 200 and 300 in which the slits shown in FIGS. 6A and 6B are formed, the above-described eddy current cannot be sufficiently reduced, and the lead frame 502 shown in FIG. 7 is used. In the magnetic sensor 500, the response speed of magnetic detection was found to be low by experiment. Specifically, the response speed of magnetic detection of the above-described conventional magnetic sensor is about 10 μs or more, and cannot be applied to applications that require a high response speed.

  Next, with reference to FIG. 1 and FIG. 2, a preferred embodiment of an IC magnetic sensor and a lead frame used therefor according to the present invention will be described in detail.

  First, FIG. 1 is a plan view of a first embodiment of a lead frame used in an IC magnetic sensor according to the present invention. In FIG. 1, a lead frame 10 is indicated by a solid line, and is bonded to an IC chip mount portion of the lead frame 10 and is electrically connected to the lead frame 10 by a well-known technique to constitute an IC magnetic sensor according to the present invention. The IC chip 40 including is indicated by a broken line.

  The lead frame 10 includes an IC chip mount portion 20 that joins the IC chip 40 and a plurality of lead portions (terminal portions) 30. In the specific embodiment shown in FIG. 1, the IC chip mount portion 20 has a base portion 21 that is relatively wide and extends in the lateral direction, and an elongated shape that protrudes from the base portion 21 in a perpendicular direction (upward in the drawing) and is spaced apart from each other. A pair of angular portions 22 and 23 are included. Here, the square portion means an elongated protrusion extending from the base portion 21. On the other hand, the lead part 30 has four leads (terminals) 31 to 34 which are parallel to each other and extend below the base part 21 of the IC chip mount part 20.

  In FIG. 1, an IC chip 40 has a substantially rectangular shape, and is positioned and disposed so as to cover the base 21 of the IC chip mount portion 20 and the pair of square portions 22 and 23 when the IC magnetic sensor is assembled. The base 21 and the corners 22 and 23 are bonded and fixed using an appropriate adhesive. With the above-described specific configuration of the IC chip mount unit 20, the IC chip 40 is reliably bonded to the IC chip mount unit 20 of the lead frame 10. That is, the parallelism between the surfaces of the IC chip 40 and the lead frame 10 is accurately maintained. Here, the dimensions of the square portions 22 and 23 of the lead frame 10 are determined in accordance with the dimensions of the IC chip 40 to be used. That is, the total dimension (vertical dimension in the figure) of the base 21 and the square part 22 (or 23) of the IC chip mounting part 20 is substantially the same as the dimension (length) of the corresponding side of the IC chip 40 to be used. Note that equal dimensions are chosen.

  Further, the IC chip 40 has a wire bonding part 42 and a magnetoelectric conversion element arranging part 44. The wire bonding portion 42 is disposed and formed along the base portion 21 of the IC chip mount portion 20 of the lead frame 10. With this specific configuration, the bonding strength between the IC chip 40 and the lead frame 10 is sufficient, and in the assembly manufacturing process of the integrated magnetic sensor, the electrical connection between the IC chip 40 and the lead portion 30 of the lead frame 10, that is, Since the wire bonding operation can be surely performed without causing an error, the IC magnetic sensor can be manufactured with high yield and high reliability.

  Furthermore, the magnetoelectric conversion element placement portion 44 of the IC chip 40 is substantially at the center position of the IC chip 40 and is sufficiently separated from the base portion 21 of the IC chip mount portion 20 and also from the adjacent angular portions 22 and 23. ing. Therefore, as will be described later, it should be noted that the response speed of magnetic detection can be significantly increased while minimizing the influence of eddy currents due to changes in the detected magnetic field.

  The electrical connection between the IC chip 40 joined to the IC chip mount portion 20 of the lead frame 10 and the leads 31 to 34 of the lead portion 30 is performed by a conventional technique, for example, wire bonding. Note that the base 21 of the IC chip mount unit 20 and one lead 33 of the lead unit 30 are integrally formed in advance and serve as one terminal of the IC chip 40, for example, a ground terminal.

  A specific example of the lead frame 10 according to the first embodiment of the present invention shown in FIG. 1 will be described. The IC chip 40 has a substantially square shape with one side of about 2.4 mm. The total length (width) of the IC chip mount portion 20 in the horizontal direction is about 5.3 mm, and the height of the base portion 21 is about 1.0 mm. Further, the lengths, widths, and intervals of the square portions 22, 23 are about 1.0 mm, about 0.38 mm, and about 1.0 mm, respectively. However, it goes without saying that the present invention is not limited to this specific example.

  Next, a lead frame according to a second embodiment of the present invention will be described with reference to FIG. The lead frame 50 of this embodiment includes an IC chip mount portion 60 and a lead portion 70, as with the lead frame 10 described above with reference to FIG. An IC chip 80 indicated by a broken line in FIG. 2 is joined to the IC chip mount portion 60. The lead part 70 has four leads 71 to 74. Here, it should be noted that the corners 22, 23 and 62 are formed symmetrically with respect to the bases 21 and 61 together with the embodiment of FIGS. As a result, the IC chip can be stably bonded or supported to the lead frame.

  Hereinafter, the lead frame 50 shown in FIG. 2 will be described focusing on the differences from the first embodiment described above with reference to FIG. The IC chip mount portion 60 of the lead frame 50 has a base portion 61 and a single square portion 62.

  The IC chip 80 disposed and bonded to the IC chip mounting portion 60 of the lead frame 50 has a pair of magnetoelectric conversion element disposing portions 84 and 85 disposed at a substantially central portion so as to be spaced apart in the lateral direction. Then, the IC chip 80 and the IC chip mount unit 60 are aligned so that one square portion 62 of the IC chip mount unit 60 coincides with the center of the pair of magnetoelectric conversion element arrangement units 84 and 85.

  Also in the lead frame 50 of this embodiment, like the lead frame 10 described above, the total size of the base 61 and the square portion 62 of the IC chip mount portion 60 is equal to the corresponding side of the IC chip 80 bonded thereto. Note that it is determined or selected according to dimensions.

  It is known that the detection output of a magnetoelectric conversion element of an IC magnetic sensor, for example, a Hall element, generally has a large variation and is weak. Therefore, it is desirable to reduce variation and increase output by using a plurality of magnetoelectric conversion elements in the IC chip and combining the output signals of the plurality of magnetoelectric conversion elements into a detection output. The lead frame 50 according to the embodiment of the present invention shown in FIG. 2 is suitable for an IC magnetic sensor including a pair of magnetoelectric conversion elements.

  In the lead frame 50 shown in FIG. 2, a specific example of the width of the square portion 62 formed in the IC chip mount portion 60 is about 1.0 mm. When the IC chip 80 includes three or more magnetoelectric conversion elements, it is desirable to form a plurality of square portions 62 and arrange the magnetoelectric conversion elements in the gaps between the square portions.

  The magnetic detection response speed was compared between the response speed of a conventional IC magnetic sensor having a slit or the like formed in the IC chip mount and the IC magnetic sensor according to the present invention. As a result, the response speed of the conventional lead frame as described above is about 10 to 12 μs, whereas the IC magnetic sensor using the lead frames 10 and 50 of the present invention shown in FIGS. It was about 2.3 μs, and it was found that the response speed was remarkably improved. This is because the influence of eddy current is effectively eliminated or greatly reduced by moving the magnetoelectric conversion element away from a conductor having a large area.

  Furthermore, according to the IC magnetic sensor and the lead frame of the present invention, the IC chip is accurately positioned and bonded to the lead frame by the base portion selected for a predetermined dimension of the IC chip mount portion and one or more square portions. Therefore, high assembly accuracy and high yield in the manufacturing process are possible, and the IC chip can be bonded to the lead frame with sufficient strength. In addition, since the wire bonding portion of the IC chip is disposed on the base portion of the IC chip mounting portion of the lead frame, a reliable wire bonding operation can be performed.

  The configuration and operation effects of the preferred embodiment of the IC magnetic sensor according to the present invention and the lead frame used therein have been described in detail above. However, it will be readily understood by those skilled in the art that various modifications and changes can be made according to the specific application without departing from the gist of the present invention.

10, 50 Lead frame 20, 60 IC chip mounting part 21, 61 Base part 22, 23, 62 Square part 40, 80 IC chip 42, 82 Wire bonding part 44, 84, 85 Magnetoelectric conversion element arrangement part

Claims (9)

In an IC magnetic sensor for bonding a rectangular IC chip having at least one magnetoelectric conversion element and a wire bonding region to an IC chip mounting portion of a lead frame,
The lead frame has a base portion on which the wire bonding region of the IC chip is placed, and at least one square portion protruding perpendicularly from the base portion,
The IC-based magnetic sensor, wherein the IC chip is arranged so that the electromagnetic conversion element does not overlap with the angular portion of the lead frame when the lead frame is viewed in plan.   2. The IC magnetic sensor according to claim 1, wherein the square portion of the lead frame is line-symmetric with respect to the base portion.   The length of the square portion is the total size of the base portion and the square portion of the lead frame, according to the size of the corresponding side of the IC chip mounted on the IC chip mount portion of the lead frame. 3. The integrated magnetic sensor according to claim 1, wherein the magnetic sensor is determined.   4. The IC magnetic sensor according to claim 1, wherein the magnetoelectric conversion element is disposed between two adjacent angular portions of the lead frame. 5.   4. The IC magnetic sensor according to claim 1, wherein a plurality of the magnetoelectric conversion elements are arranged on both sides of the square portion of the lead frame. A lead frame used for an integrated magnetic sensor having an approximately rectangular IC chip including at least one magnetoelectric conversion element,
A base portion on which a region including the connection pad of the IC chip is placed; and at least one square portion protruding perpendicularly from the base portion;
The length of the square portion is the total size of the base portion and the square portion of the lead frame, according to the size of the corresponding side of the IC chip mounted on the IC chip mount portion of the lead frame. A lead frame used for an IC magnetic sensor characterized by being determined.   The lead frame used for an IC-based magnetic sensor according to claim 6, wherein the square portion of the lead frame is formed in line symmetry with respect to the base portion.   The said square part of the said lead frame is a plurality mutually parallel, The said electromagnetic conversion element of the said IC chip is arrange | positioned between the said square parts, The Claim 6 or 7 characterized by the above-mentioned. Lead frame used in IC magnetic sensors. 8. The magnetized IC according to claim 6, wherein the square portion of the lead frame is single, and the magnetoelectric conversion element of the IC chip is disposed on both sides of the square portion. 9. Lead frame used for sensors.

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