JP7097671B2 - IC magnetic sensor and lead frame used for it - Google Patents

Description

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

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 magnetic-electric conversion element (hereinafter, simply referred to as a magnetic-electric conversion element). Various magnetic sensors that output as electrical signals have been developed and are commercially available.

Such magnetic sensors are used with a large number of signal or control conductors in electronic devices such as vehicles or electronic application devices to detect currents (input currents) flowing through these conductors. It is generally desirable for these devices to be small, lightweight and inexpensive. Further, since the detection output of these magnetometer conversion elements is weak and changes depending on the ambient temperature and other conditions, one or more magnetometer conversion elements, an amplifier of the detection output, a detection output correction circuit, and the like are mounted on a semiconductor substrate (sub). It is desirable to make an IC-based magnetic sensor integrated or integrated on a straight) to form an IC chip.

In general, a large number of ICs are simultaneously formed on a semiconductor substrate by a well-known technique, bonded to a lead frame made of a conductive metal, and after a predetermined electrical connection, are individually divided to form an IC magnetic sensor. To. Therefore, the lead frame has an IC chip mount portion for supporting the IC chip and a plurality of lead portions (terminal portions). The terminal (or connection pad) of the IC chip and the lead portion of the lead frame are generally electrically connected by a wire bonding technique using a thin gold wire.

In order to convert a magnetic sensor into an IC, an IC chip in which various electronic circuits such as a magnetic-electric conversion element and an amplifier circuit are integrally formed is bonded (or bonded) to the IC pad mount portion of the lead frame with an appropriate adhesive. , Necessary physical support and heat dissipation of generated heat. 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 with epoxy resin or the like to protect it. Here, the IC magnetometer means a magnetic detection device provided with an IC chip including a magnetic-electric conversion element and a lead frame, and manufactured as described above.

Such an IC magnetic sensor is commercially available and disclosed in some patent documents. An elongated slit extending substantially over the IC chip mount portion, which is a support portion of the lead frame for joining the IC chip to the lead frame having a sufficient area, is provided, and the IC chip mount of the lead frame is provided due to a change in the magnetic field to be measured. A lead frame for an IC that prevents a measurement error or the like due to an eddy current generated in a portion is disclosed (see, for example, Patent Document 1 and Patent Document 2).

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

US Pat. No. 6,853,178 US Patent Publication No. 6922048 Japanese Patent No. 5676635

In order to obtain an IC-based magnetic sensor with few detection errors and good magnetic detection response speed, the conductor should be removed or kept away from the vicinity of the magnetic-electric conversion element as much as possible in order to reduce the influence of the above-mentioned eddy current. It turned 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 magnetic-electric conversion element in the IC chip mount region.

However, if the IC chip is not accurately arranged, that is, joined and fixed to the lead frame, the wire bonding work, which is a subsequent process, becomes difficult, and the electrical connection between the lead frame and the IC chip becomes defective. Insufficient bonding strength reduces product yield and reliability.

The present invention has been made in view of the above-mentioned various problems of the prior art, and an object of the present invention is to provide an IC magnetometer and a lead frame used for solving or alleviating these problems.

In order to solve the above-mentioned problems and achieve the above-mentioned object, the IC magnetic sensor of the present invention adopts the following characteristic configuration. That is, it is an IC-ized magnetic sensor that joins a rectangular IC chip having at least one magnetic-electric conversion element and a wire bonding region to the IC chip mount portion of the lead frame, and the wire bonding region of the IC chip is placed on the lead frame. The IC chip has a base portion to be formed and at least one square portion protruding at a right angle from the base portion, so that the magnetic and electrical conversion element does not overlap with the square portion of the lead frame when the lead frame is viewed in a plan view. It is characterized by being arranged.

Here, the square portion of the lead frame is formed line-symmetrically with respect to the base portion. Further, the length of the square portion of the lead frame is determined by determining the total dimension of the base portion and the square portion of the lead frame according to the dimension of the corresponding side of the IC chip mounted on the IC chip mount portion of the lead frame. Will be done. The magnetic-electric conversion element of the IC chip is arranged between the two square portions of the lead frame. Further, there are a plurality of magnetic / electric conversion elements arranged on both sides of the square portion of the lead frame.

Further, the lead frame used for the IC magnetic sensor of the present invention adopts the following characteristic configuration. That is, a lead frame used for an IC magnetometer having a substantially rectangular IC chip including at least one magnetic / electrical conversion element, and a base on which a connection pad region of the IC chip is arranged.

It is provided with at least one square portion protruding at a right angle from this base portion, and the length of the square portion is such that the total dimension of the base portion and the square portion of the lead frame is mounted on the IC chip mount portion of the lead frame. It is determined according to the dimensions of the corresponding sides of the IC chip.

Here, the square portion of the lead frame is formed line-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 angular portion, and magnetic / electrical conversion elements of the IC chip are arranged on both sides thereof.

Since the IC magnetic sensor according to the present invention has an elongated square portion in which the lead frame protrudes at right angles to the base portion, the conductor arranged in the vicinity of the magnetic-electric conversion element of the IC chip is the minimum, so that the eddy current is eddy current. It suppresses the adverse effects of magnetic detection and greatly improves the response speed of magnetic detection. In addition, since the square portion of the lead frame is line-symmetrical with respect to the base and has a length corresponding to the dimension of the corresponding side of the IC chip, it is stably mounted on the lead frame with accurate parallelism and sufficient strength. It is possible to carry out post-processing such as wire bonding with high reliability, and it is possible to realize high yield, reliability and low price of IC magnetic sensor. Further, it is possible to correspond to an IC chip having a single or a plurality of magnetic-electric conversion elements as needed.

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

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

It is a top view which shows 1st Embodiment of the lead frame used for the IC magnetic sensor by this invention. It is a top view which shows the 2nd Embodiment of the lead frame used for the IC magnetic sensor by this invention. It is explanatory drawing of the specific example which applies the IC magnetic sensor of this invention. FIG. 3 is an explanatory diagram of an IC-based magnetic sensor according to the present invention, which is arranged and used in a gap of a magnetic core (simply referred to as a core) in FIG. It is explanatory drawing of the eddy current generated in a conductor when a conductor such as a lead frame and a changing magnetic force line are chained. A conventional example of a lead frame for an IC is shown, (a) is a plan view, and (b) is a plan view showing another example of an IC chip mount portion. It is a top view which shows the other conventional example of the lead frame used for the IC magnetic sensor.

Next, an example of the IC magnetic sensor according to the present invention and the lead frame used thereof will be described in detail with reference to the attached drawings. It should be noted that the examples shown here are merely examples of the present invention and do not limit the present invention in any way, and various modifications can be made according to specific uses.

First, FIG. 3 is an explanatory diagram showing an application example of the IC magnetic sensor according to the present invention. In this application example, the IC magnetometer 100 including a magnetic-electric conversion element (for example, a Hall element) is arranged in a gap 112 (see FIG. 4) formed in a core 110 through which a conductor 120 through which an input current flows passes. There is. The core 110 collects a magnetic field generated around the conductor 120 due to the flow of an input current. The IC magnetic sensor 100 is supplied with a power source or the like (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. It is desirable that the amplifier 130 is integrally formed with the IC magnetic sensor 100, that is, it is made into an IC.

Next, FIG. 4 is an enlarged view of a part of the core 110 in which the IC magnetic sensor 100 of FIG. 3 is arranged. The IC magnetic sensor 100 arranged in the minute void 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 formed by joining to the conductive lead frame 102, and is protected by covering the whole with an epoxy resin or the like except for the connection portion (lead terminal portion) to the outside.

Magnetic force lines are generated inside the core 110 and in the gap 112 of FIG. 4 due to 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 a function of canceling the original magnetic force lines (that is, the magnetic force lines generated around the conductor 120 by the input current), it is desirable for the IC magnetic sensor 100 to minimize this.

Here, in order to help understanding the problems and effects of the present invention, first, refer to FIGS. 6 and 7 for the prior art for reducing the above-mentioned eddy current generated in the conductor of the IC chip mount portion of the lead frame 102. I will explain.

FIG. 6 is a plan view of the conventional lead frame disclosed in Patent Document 1 and Patent Document 2 described above. The 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 thereof. With this slit 205, the above-mentioned eddy current is suppressed with reference to FIG. On the other hand, in FIG. 6B, for the same purpose as in FIG. 6A, 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 other side 304 facing the other side 304. 300 is disclosed.

Further, 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. In the lead frame 502, in order to reduce the above-mentioned eddy current, a first slot 510 extending from one side to the other side and a second slot 520 continuous from the end of the first slot 510 are formed. 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 aligned with these slots 510 and 520.

However, in the lead frames 200 and 300 in which the slits shown in FIGS. 6 (a) and 6 (b) are formed, the above-mentioned eddy current cannot be sufficiently reduced, and the lead frame 502 shown in FIG. 7 is used. Experiments have shown that the magnetic sensor 500 has a low response speed for magnetic detection. Specifically, the response speed of magnetic detection of the magnetic sensor according to the above-mentioned conventional technique is about 10 μs or more, and it cannot be applied to applications requiring a high response speed.

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

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

The lead frame 10 is composed of an IC chip mount portion 20 for joining 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 relatively wide base portion 21 extending in the lateral direction, and an elongated base portion 21 projecting from the base portion 21 in a right angle direction (upward in the drawing) and separated from each other. It contains a pair of square portions 22, 23. Here, the square portion means an elongated protruding portion extending from the base portion 21. On the other hand, the lead portion 30 has four leads (terminals) 31 to 34 parallel to each other extending below the base portion 21 of the IC chip mount portion 20.

In FIG. 1, the IC chip 40 has a substantially rectangular shape, and is positioned and arranged so as to cover the base 21 of the IC chip mount portion 20 and the pair of square portions 22, 23 at the time of assembling the IC magnetic sensor. , Are joined and fixed to these bases 21 and square portions 22 and 23 using an appropriate adhesive. With the above-mentioned specific configuration of the IC chip mount portion 20, the IC chip 40 is reliably joined to the IC chip mount portion 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 according to the dimensions of the IC chip 40 used. That is, the total dimension (vertical dimension in the figure) of the base portion 21 and the square portion 22 (or 23) of the IC chip mount portion 20 is abbreviated as the dimension (length) of the corresponding side of the IC chip 40 used. Note that they are selected to have the same dimensions.

Further, the IC chip 40 has a wire bonding portion 42 and a magnetic-electric conversion element arranging portion 44. The wire bonding portion 42 is arranged 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 process of assembling and manufacturing the IC 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 work can be reliably performed without causing an error, the IC magnetic sensor can be manufactured with high yield and high reliability.

Further, the magnetic-electric conversion element arranging 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 separated from the adjacent square portions 22 and 23. ing. Therefore, as will be described later, it should be noted that the influence of the eddy current due to the change in the detected magnetic field can be minimized and the response speed of the magnetic detection can be significantly increased.

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. The base 21 of the IC chip mount portion 20 and one lead 33 of the lead portion 30 are integrally formed in advance, and 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 is a substantially square having a side of about 2.4 mm. The total length (width) of the IC chip mount portion 20 in the lateral direction is about 5.3 mm, and the height of the base portion 21 is about 1.0 mm. The length, width and spacing of the square portions 22 and 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, the lead frame according to the 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, similarly to the lead frame 10 described above with reference to FIG. 1. The IC chip 80 shown by the broken line in FIG. 2 is joined to the IC chip mount portion 60. The lead portion 70 has four leads 71 to 74. It should be noted here that, with the embodiments of FIGS. 1 and 2, the angular portions 22, 23 and 62 are formed line-symmetrically with respect to the base portions 21 and 61. This makes it possible to stably join or support the IC chip to the lead frame.

Hereinafter, the lead frame 50 shown in FIG. 2 will be described with reference to FIG. 1, focusing on the differences from the first embodiment described above. The IC chip mount portion 60 of the lead frame 50 has a base 61 and a single square portion 62.

The IC chip 80 arranged and joined to the IC chip mount portion 60 of the lead frame 50 has a pair of magnetic and electrical conversion element arranging portions 84 and 85 arranged laterally spaced apart from each other in a substantially central portion thereof. Then, the IC chip 80 and the IC chip mount portion 60 are aligned so that one square portion 62 of the IC chip mount portion 60 coincides with the center of the pair of magnetic / electric conversion element arrangement portions 84 and 85.

Also in the lead frame 50 of this embodiment, similarly to the lead frame 10 described above, the total dimensions of the base portion 61 and the square portion 62 of the IC chip mount portion 60 are the corresponding sides of the IC chip 80 joined therein. Note that it is determined or selected according to the dimensions.

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

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

The response speed of magnetic detection was compared with the response speed of the conventional IC-based magnetic sensor having a slit or the like formed in the IC chip mount portion and the IC-based 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. 1 and 2 has a response speed of about 10 to 12 μs. It was about 2.3 μs, and it was found that the response speed was significantly improved. The reason is that the influence of the eddy current is effectively eliminated or significantly reduced by keeping the magnetic / electric conversion element away from the conductor having a large area.

Moreover, according to the IC magnetic sensor and the lead frame of the present invention, the IC chip is accurately positioned and joined to the lead frame by the base portion selected to the predetermined dimensions 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. Further, since the wire bonding portion of the IC chip is arranged on the base portion of the IC chip mounting portion of the lead frame, reliable wire bonding work is possible.

In the above, the configuration and operation / effect of a suitable embodiment of the IC magnetic sensor according to the present invention and the lead frame used thereof have been described in detail. However, those skilled in the art can easily understand that various modifications can be made according to a specific application without departing from the gist of the present invention.

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

Claims (2)

In an IC magnetometer in which a substantially rectangular IC chip having a magnetic conversion element and a wire bonding region is bonded to an IC chip mount portion of a lead frame.
The lead frame is a base portion on which the wire bonding region of the IC chip is placed, and a pair of elongated angular portions protruding from the base portion in a perpendicular direction and separated from each other, and the right angle of the base portion. It has a pair of squares that are smaller in width than the height in the direction and the spacing of the pair of squares and have a length in the right angle greater than the width .
In the IC chip, the magnetic conversion element is located at a position separated from the pair of square portions and the base portion of the lead frame, and the two sides parallel to the right angle direction are larger than the pair of square portions. IC magnetic sensors characterized in that they are arranged at positions on the outside . A lead frame used for an IC magnetometer having a magnetic-electric conversion element and a substantially rectangular IC chip having a wire bonding region.
A base on which the wire bonding region of the IC chip is placed, and a pair of elongated square portions protruding from the base in a right-angle direction and separated from each other, and the height of the base in the right-angle direction and the height of the base. It has a pair of square portions having a width smaller than the distance between the pair of square portions and having a length in the right angle direction larger than the width .
In the IC chip, the magnetic conversion element is located at a position separated from the pair of square portions and the base portion, and two sides parallel to the right-angled direction are outside the pair of square portions. A lead frame used for an IC magnetic sensor characterized by being placed at a position .

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