JP2002368304A - Hall element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a Hall element which has a large Hall output voltage without varying package thickness. SOLUTION: The Hall element 1 is installed on the surface of a mount substrate 6 and stored in a resin package which can detect a magnetic field. In the Hall element 1; a lead frame 5, a pellet 3, a magnetism sensitive surface 2, and a magnetism convergence chip 4 are arranged in order from the side of the mount substrate 6, and magnetic flux from the side of the magnetism convergence chip is received. The lead frame 5 has its part outside of the resin package 7 formed of a part parallel to the bottom surface of the resin package 7, and the lead frame 5 is straight and horizontal from two sides of the bottom surface of the resin package 7 to the outside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Hall element, and more particularly, to a Hall element configured to extract a voltage signal proportional to the magnetic flux density of a magnetic field, such as a semiconductor magneto-electric conversion element utilizing the Hall effect. Related to the element.

[0002]

2. Description of the Related Art Conventional Hall elements are used in recent electronic devices,
In particular, CD-ROM and DVD-RO of VTRs and personal computers
It is widely used as a non-contact sensor for precision controlled small DC brushless motors used in M. In addition to small motors, future development is expected in fields such as non-contact position sensors and current sensors.

In general, the package shape of an electronic component is
The method can be classified into two methods depending on the connection method to the printed wiring board. They are a lead insertion type and a surface mount type. The lead insertion type inserts a lead of a package into a through hole of a substrate and solders the package, and has a disadvantage that the package size easily increases as the number of pins increases. On the other hand, the surface mount type is one in which leads are mounted on the surface of a substrate by soldering, and has been developed from the demand for miniaturization, thinning, and multifunctionality. The surface mounting type has been applied on a printed wiring board instead of the lead insertion type, and the component mounting density on the wiring board has been rapidly improved.
The surface mount type has been found to be advantageous not only in miniaturization and thinning, but also in terms of automation of assembly and electrical characteristics, and has been widely used.

FIGS. 2 (a), 2 (b) and 2 (c) show various package shapes used in recent small transistors. FIG. 2 (a) shows a mainstream gull-wing type. (B) and (c) show a flat lead type and a leadless type aiming at further thinning and enlargement of a mountable chip size. In the figure, reference numeral 11 denotes a lead frame, 13 denotes a flat lead frame, and 15 denotes a lead frame.
Indicates an insertion lead, and 12, 14, and 16 indicate packages.

[0005] The shape of the package used for the Hall element has generally been developed similarly to discrete components such as diodes and transistors. Initially, printed wiring boards were provided with insertion holes, and leads were inserted into these holes and soldered and fixed on the other side of the board, but recently lead-surface mounting types have become the mainstream. ing.

FIGS. 3 (a), 3 (b) and 3 (c) are views showing an example of a package shape used so far for a Hall element. The package shape of the Hall element shown in FIG. FIG. 3B shows a DIP type package having a gull wing type lead shape, and FIG.
(C) shows a package called SIP type.
In the drawings, reference numeral 21 denotes a mounting substrate, 22 denotes a magnetically sensitive surface, 23 denotes a magnetic focusing chip, 24 denotes an element substrate, 25 denotes a lead frame, and 26 denotes a molding resin.

The internal structure of the Hall element shown in FIG. 3A is called a magnetic amplification type. The magnetic sensing surface 22 made of an InSb thin film or the like is provided with a magnetic focusing chip made of a ferromagnetic material such as ferrite for magnetic amplification. 23 and an element substrate 24 having a structure sandwiched between substrates also made of a ferromagnetic material
Are provided on a lead frame 25, and these are sealed with a mold resin 26. The lead shape is a surface mount type gull wing type, which is advantageous in terms of thermal stress acting on a solder joint, and is a typical shape of the current surface mount type.

A bending mold is generally used as a gull-wing type lead-shaped bending method. The main bending dies are the ironing method in which the bending punch descends in the vertical direction and squeezes the lead to form a shape similar to a bending die. There are two types: a roller type and a roller type that uses a roller instead of a punch to prevent the lead from sticking. Recently, the load on leads has been reduced,
In addition, the roller method is often used from the viewpoint of the stability of the forming shape.

In order to stably perform such bending of the lead frame, it is easier if the lead portion to be bent has a certain length or more. In the case of the gull wing type, the package is bent downward on the package side and the lead tip is bent upward, so if the lead portion to be bent is short, cracks will occur due to bending in a narrow range, and the bent shape Are likely to be unstable. For these reasons, the gull-wing type package actually used is generally provided with a thickness difference between the top and bottom of the lead frame, and the thickness in the direction in which the lead frame is bent is generally increased. Shape is used.

The chip or pellet incorporated in the package is mounted on the side where the thickness of the package is large. As a result, as shown in FIG. 3A, a gull-wing type Hall element senses a magnetic field. The magneto-sensitive surface is generally arranged facing downward, that is, facing the mounting substrate side.

Further, when bending the lead frame, depending on the bending method and conditions, stress is applied to the lead during the bending, and the opening between the lead and the boundary between the mold resin body and the lead is more or less less. There is a possibility of generating defects such as voids. The size of the void generated by bending the lead frame also depends on the thickness of the resin such as the thickness of the package. That is, in the cross-sectional shape of the Hall element shown in FIG. 3A, when the side on which the chip is mounted on the island of the lead frame is the lower side of the island and the opposite side where the chip is not mounted is the upper side of the island, the direction in which the lead is bent is A large stress is applied to the upper side of the island which is the opposite side.

According to the study of the present inventors, the opening due to the stress generated by the bending process is greatly affected by the thickness of the resin on the upper side of the island, and when the thickness is reduced, the degree of occurrence of the opening tends to increase. Was done. Therefore, in order to prevent defects due to the forming bending process, there is a thickness that should be the lower limit, and the size of the mini-mold and super-mini-mold was about 150 μm.

[0013]

As described above, in a Hall element having a gull-wing type lead shape,
A pellet having a magneto-sensitive surface is placed in a downward state after mounting. Normally, the magnet surface is arranged on the surface side of the Hall element after mounting, that is, on the side where the pellet is not mounted on the lead frame, so there is a physical gap between the magnet surface and the magnetically sensitive surface for detecting the magnetic field. It was a situation that would occur. Since the output of the Hall element is greatly affected by the distance from the magnet to the magneto-sensitive surface, such a gap has been a major factor impeding the output (sensitivity) of the Hall element.

As described above, the package strength is important for suppressing the occurrence of defects in the forming bending process, and the effect of increasing the thickness of the package resin is great for securing the package strength. In conventional gull-wing Hall elements, the resin thickness from the island opposite to the bending direction to the package surface cannot be reduced in order to suppress defects due to bending, and as a result, the allowable chips that can be put in the package Height was to be limited.

That is, in the case of a magnetic amplification type Hall element as shown in FIG. 3A, the height of the magnetic focusing chip 23 for magnetic amplification is limited, and the output of the Hall element is The higher the height, the greater the output that can be obtained, which has led to limiting the output (sensitivity) from the Hall element. For example, in a mini-mold type having a package thickness of 1.1 mm, the height of the magnetic focusing chip 23 is 0.2 mm.
7 mm, the height of the magnetic focusing chip 23 is 0.18 m in the super mini mold having a package thickness of 0.8 mm.
m, which is almost the upper limit of the chip height.
The ratio of the thickness of the magnetic focusing chip 23 to the thickness of 6 is:
They were 24.5% and 22.5%, respectively.

The present invention is particularly effective for a thin device having a package thickness of 0.8 mm or less. If the package thickness is thicker than a certain level, even with the conventional gull wing type, a magnetic focusing chip with a certain height or more can be mounted, and the magnetic amplifying effect is within a certain range of the magnetic flux density where a Hall element is used practically. In the case of a magnetic focusing chip having a larger size, the effect of the present invention is reduced because the amplification effect is reduced due to the saturation phenomenon of magnetic flux.

Further, the present invention is more effective when the ratio of the height of the magnetic convergence chip to the package thickness is desired to be 30% or more. That is, the present invention provides a method for increasing the height of a magnetic focusing chip, which has been conventionally restricted, while maintaining the package thickness.

That is, the magnetic amplification type Hall element is mounted on a flat lead type package.
In a thin device of 8 mm or less, when the height of the magnetic focusing chip for magnetic amplification is set to 30% or more of the package thickness, the effect of the present invention is maximized.

The present invention has been made in view of such circumstances, and an object thereof is to provide a large Hall output voltage, that is, a large Hall output voltage without changing the package thickness as compared with a conventional gull-wing type Hall element. An object of the present invention is to provide a Hall element with high sensitivity.

[0020]

According to the present invention, in order to achieve the above object, the invention according to claim 1 is provided on a surface of a mounting board (6), and is provided with a resin package capable of detecting a magnetic field. A Hall element (1) comprising a pellet (3) having a magneto-sensitive surface (2) and a lead having a pellet mounting surface (5a) to which the pellet (3) is fixed. A frame outside the resin package and a portion parallel to the bottom surface of the resin package; 5) is immediately horizontal from two sides of the bottom surface of the resin package (7) to the outside.

The invention described in claim 2 is the first invention.
In the invention described in (1), a magnetic focusing chip (4) is provided on the magneto-sensitive surface (2) of the pellet (3).

The invention described in claim 3 is the same as the invention described in claim 2.
In the invention described in the above, the internal configuration of the Hall element,
The lead frame (5), the pellet (3), the magneto-sensitive surface (2), and the magnetic focusing chip (4) are arranged in this order from the substrate (6) side, and from the magnetic focusing chip (4) side. It is characterized by having a form that receives a magnetic flux.

In the conventional gull-wing Hall element, after being mounted on the printed wiring board, the element form is such that a pellet having a magneto-sensitive surface for sensing a magnetic field is arranged in the same direction as the magnet surface via a lead frame. Therefore, there is a limit in reducing the detection distance. In contrast, by incorporating the Hall element having the magnetic amplification structure of the present invention into a flat lead type package, it is possible to arrange the magneto-sensitive surface to face the magnet surface, and the detection distance can be greatly reduced. As a result, a Hall element having a large output, that is, a highly sensitive Hall element can be obtained.

In the conventional gull wing shape involving bending of the lead frame, the thickness of the resin from the island on the opposite side to the bending direction to the surface of the package must be reduced in order to maintain the package strength to withstand the stress generated during bending. Could not be done. On the other hand, by incorporating the Hall element having the magnetic amplification structure of the present invention into a flat lead type package having no lead bending process, the requirement for the package strength is reduced, and the package is moved from the island on which the magnetic focusing chip is not mounted to the package. The thickness of the resin up to the surface can be reduced, and if the overall package thickness is not changed, the height of the magnetic focusing chip can be increased, resulting in a large output, that is, high sensitivity. Hall elements can now be obtained. In addition, when the height of the magnetic focusing chip is not changed, the entire package thickness can be reduced.

Further, as a side effect of the present invention, it is possible to omit the forming process, to omit inspection of appearance defects such as bending, twisting and warping of the lead frame, and to increase the number of elements per unit area of the lead frame. It can also be expected to have cost reduction effects.

[0026]

Embodiments of the present invention will be described below with reference to the drawings.

[Embodiment 1] FIG. 1 is a cross-sectional view showing an embodiment of a Hall element according to the present invention.
Is a magnetic sensing surface, 3 is a pellet, 4 is a magnetic focusing chip, 5 is a lead frame, 5a is a pellet mounting surface, 6 is a mounting board,
Reference numeral 7 denotes a resin package.

The Hall element 1 is set on the surface of the mounting substrate 6 and is housed in a resin package capable of detecting a magnetic field. The Hall element 1 includes a pellet 3 having a magneto-sensitive surface 2 and a magnetic focusing chip 4,
And a lead frame 5 having a pellet mounting surface 5a to which the lead frame 5 is fixed.

The lead frame 5 has a portion outside the resin package 7 parallel to the bottom surface of the resin package 7, and the lead frame 5 is immediately horizontal from two sides of the bottom surface of the resin package 7 to the outside. It is configured to be.

The internal structure of the Hall element 1 includes a lead frame 5, a pellet 3, a magneto-sensitive surface 2,
The magnetic focusing chip 4 is arranged in this order, and has a form in which a magnetic flux is received from the magnetic focusing chip 4 side.

Next, a method of manufacturing the Hall element of the present invention will be described below. First, on a ferrite substrate having a thickness of 0.25 mm, a thickness of 0.8 μm was formed by a vacuum evaporation method.
Are bonded together via an insulating adhesive. Then, a sensitive part and an electrode are formed on the InSb thin film by etching and plating, and a ferrite height of 0.1 mm is formed on the formed sensitive part via an insulating adhesive.
A magnetic amplification type pellet on which an 8 mm magnetic focusing chip was mounted was produced.

Next, in Example 1, the prepared pellets were placed on a flat lead type lead frame as shown in FIG.
In Comparative Example 1 shown in (a), each was die-bonded on a gull-wing type lead frame, and further wire-bonded to connect the electrode of the pellet and the lead frame with a gold wire. Next, in Example 1, molding was performed using a flat lead type mold using an epoxy-based mold resin, and in Comparative Example 1, sealing was performed using a gull wing mold. The dies were set so that the total package thickness of both dies was 0.8 mm.

After that, since Example 1 is a flat lead type which does not require forming, deburring, lead plating,
After a trimming step, a sample was obtained. On the other hand, Comparative Example 1
Is a gull-wing type package, and was subjected to deburring, lead plating, trimming and forming steps to obtain a sample. Following the process described above,
In each of Example 1 and Comparative Example 1, 100,000 Hall elements were prototyped.

The Hall element thus produced was surface-mounted on a printed wiring board, and the Hall output voltage (sensitivity) was measured. At this time, the distance from the substrate surface of the printed wiring to the surface of the Hall element was set to be the same in both Example 1 and Comparative Example 1, and the height was about 0.85 mm. The positional relationship between the magneto-sensitive surface inside the package after mounting and the magnet surface provided outside is as follows. In Example 1, the magneto-sensitive surface and the magnet surface face each other, and in Comparative Example 1, the pellet having the magneto-sensitive surface forms the lead frame. And the magnets are arranged in the same direction as the magnet surface.

Table 1 shows the measurement results of the Hall output voltage. The measurement conditions were constant voltage drive, and applied magnetic field B was 50
mT and input voltage Vin were 1V. At this time, the distance from the mounting substrate surface to the magnet surface was about 20 mm.
And Comparative Example 1 were measured with the same measuring instrument.

[0036]

[Table 1] Hall output voltage

By using a flat lead type package, the distance between the magnet surface and the magneto-sensitive surface can be reduced even when a pellet having the same configuration such as the height of a magnetic focusing chip is incorporated. An improvement in Hall voltage of 32%, that is, an increase in sensitivity was observed.

[Example 2] As in Example 1, a Hall element was prototyped by the following process. First, the thickness 0.25
A 0.8 μm-thick InSb thin film formed by a vacuum evaporation method is bonded on a ferrite substrate having a thickness of 2 mm via an insulating adhesive. Then, a sensing part and an electrode are formed on the InSb thin film by etching and plating, and a magnetic amplification type pellet on which a ferrite magnetic focusing chip is mounted via an insulating adhesive is formed on the sensing part thus formed. Produced.

Next, the prepared pellets were
The electrode of the pellet was connected to the lead frame with a gold wire by die bonding on the lead frame of the above, followed by wire bonding, and then packaged with an epoxy-based mold resin. Thereafter, through a deburring, lead plating, and trimming processes, a flat lead 10
Ten thousand Hall elements were prototyped.

Comparative Example 1 The package thickness was 0.8 mm.
Is a conventional gull-wing type package, the height of the magnetic focusing chip was 0.18 mm, and the ratio of the thickness of the magnetic focusing chip to the package thickness was 22.5%.
At this time, the skin layer thickness from the upper surface of the magnetic focusing chip to the package surface is 0.11 mm, and the thickness from the island on the side opposite to the pellet to the package surface is:
The thickness was set to 0.16 mm so as to withstand the stress during forming.

On the other hand, in the embodiment 2 mounted on the flat lead type package of the present invention, the skin layer thickness from the top surface of the magnetic focusing chip to the package surface is set to 0.
In the case of 11 mm, the height of the magnetic focusing tip is 0.27 m
m, and the ratio of the thickness of the magnetic focusing chip to the thickness of the package can be 33.8%.
At this time, the thickness from the island on the side opposite to the pellet to the surface of the package is reduced because the forming step is not required, so that the requirement for the package strength with respect to the stress is relaxed.
7 mm.

Table 2 shows a comparison of Hall output voltages (sensitivities) of the Hall elements manufactured in Example 2 and Comparative Example 1. The measurement conditions were a constant voltage drive, an applied magnetic field B of 50 mT, and an input voltage Vin of 1 V.

[0043]

[Table 2] Hall output voltage

By using a flat lead type package, the height of the magnetic focusing chip can be increased from 0.18 mm to 0.27 mm without changing the package thickness, and the magnetically sensitive surface and the magnet surface are brought close to each other. In combination with the effect, the Hall output voltage was improved by about 43%, that is, the sensitivity was increased.

The reliability of the Hall elements of Example 2 and Comparative Example 1 was evaluated by a reliability test in accordance with JIS C7021, ie, a humidity test, a high-temperature energization, a high-temperature test, and a temperature cycle test. No problems were observed in Comparative Example 1.

[Embodiment 3] FIG. 4 is a sectional view showing another embodiment of the Hall element of the present invention. In the figure, reference numeral 31 denotes a Hall element without a magnetic focusing chip, 32 denotes a magneto-sensitive surface, 3
Reference numeral 3 denotes a pallet, 34 denotes a lead frame, 35 denotes a mold resin, and 36 denotes a mounting board.

Next, a method for manufacturing the Hall element of the present invention will be described below.

First, in Example 3, a 0.8 μm-thick InSb thin film formed on a ceramic substrate by a vacuum evaporation method is bonded via an insulating adhesive. And InS
(b) A sensing portion and an electrode on the thin film were formed by etching and plating, and the formed sensing portion was covered with a silicone resin to produce a pellet.

Next, the prepared pellets were die-bonded on a flat lead type lead frame in Example 3 and on a gull wing type lead frame in Comparative Example 2, and further wire-bonded. The electrode of the pellet and the lead frame were connected by a gold wire, and then sealed with a mold resin using a mold suitable for the type of the lead frame.

Next, in Example 3, stripping, lead plating, and trimming were performed. In Comparative Example 2, 100,000 Hall elements were trial-produced, including forming and embedding.

The Hall element thus produced was surface-mounted on a printed wiring board, and the Hall output voltage was measured.
The positional relationship between the magneto-sensitive surface inside the package after mounting and the magnet surface provided outside is as follows. In Example 3, the disclosure surface and the magnet surface are opposed to each other. In Comparative Example 2, the pellet having the magneto-sensitive surface is the lead frame. And the magnets are arranged in the same direction as the magnet surface.

Table 3 below shows the measurement results of the Hall output voltage. The measurement conditions were constant voltage drive, and applied magnetic field B was 50
mT and input voltage Vin were 1V.

[0053]

[Table 3] Hall output voltage

By using a flat lead type package, the distance between the magnet surface and the magneto-sensitive surface can be reduced,
As an effect, the sensitivity was increased by about 24%.

Example 4 A Hall element using GaAs as a semiconductor material in Example 4 was manufactured. First, GaAs
After implanting Si ions into the s-substrate and applying arsine annealing, a sensitive part was formed by etching and then an electrode was formed by vapor deposition to produce a pellet.

The prepared pellets were formed into a flat lead type shape in Example 4 and a gull wing type shape in Comparative Example 3 and subjected to the same treatment as in Example 3 and Comparative Example 2 to obtain 100,000 pieces. Each sample was prototyped.

The Hall element thus produced was surface-mounted on a printed wiring board, and the Hall output voltage was measured.
The positional relationship between the magneto-sensitive surface inside the package after mounting and the magnet surface provided outside is as follows. In Example 3, the disclosure surface and the magnet surface are opposed to each other. In Comparative Example 2, the pellet having the magneto-sensitive surface is the lead frame. And the magnets are arranged in the same direction as the magnet surface.

Table 4 shows the measurement results of the Hall output voltage. The measurement conditions were constant voltage drive, and applied magnetic field B was 50
mT and the input voltage Vin were 6V.

[0059]

[Table 4] Hall output voltage

By using the flat lead type package, the sensitivity was increased by about 22%.

[0061]

As described above, according to the present invention, the Hall element is provided with the pellet having the magneto-sensitive surface and the lead frame having the pellet mounting surface to which the pellet is fixed. Since the portion outside the resin package is parallel to the bottom surface of the resin package and the lead frame is immediately horizontal from two sides of the bottom surface of the resin package to the outside, the conventional gull-wing type Hall element Thus, it is possible to provide a Hall element having a large Hall output voltage, that is, a highly sensitive Hall element without changing the package thickness. Also, after mounting,
Since the pellets are arranged upward, the distance between the magneto-sensitive surface and the magnet becomes shorter, which is advantageous from the viewpoint of mounting.

In the conventional gull wing type, there are quality control items such as abnormal lead bending, twisting and warping due to the lead bending process. However, the flat lead type eliminates the bending process, thereby improving the inspection yield. This is, of course, also effective in terms of increasing the efficiency of the work process and reducing costs.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a Hall element of the present invention.

FIGS. 2A and 2B are views showing a form of a package of a general small transistor, wherein FIG.
(B) and (c) show a flat lead type and a leadless type aiming at further thinning and enlargement of a mountable chip size.

FIGS. 3A and 3B are diagrams showing the form of a package used for a Hall element. FIG. 3A shows a Hall element package having a gull-wing type lead shape, and FIG. 3B shows a DIP package. Type, (c) is SIP
Shows a package called a type.

FIG. 4 is a sectional view showing another embodiment of the Hall element of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hall element 2 Magnetic-sensitive surface 3 Pellet 4 Magnetic focusing chip 5 Lead frame 5a Pellet mounting surface 6 Mounting substrate 7 Resin package 11 Lead frame 12, 14, 16 Package 13 Flat lead frame 15 Insertion lead 21 Mounting substrate 22 Magnetic-sensitive surface 23 Magnetic focusing chip 24 Element substrate (pellet) 25 Lead frame 26 Mold resin 31 Hall element 32 Sensitive surface 33 pellet 34 Lead frame 35 Mold resin 36 Mounting substrate

Claims (3)

[Claims] 1. A hall element installed on a surface of a mounting substrate and housed in a resin package capable of detecting a magnetic field, the hall element comprising a pellet having a magneto-sensitive surface, and a pellet installation to which the pellet is fixed. A lead frame having a surface, wherein the shape of the lead frame is such that a portion outside the resin package is a portion parallel to a bottom surface of the resin package, and the lead frame is formed on two sides of the bottom surface of the resin package. A hall element that is immediately horizontal from the outside to the outside. 2. The Hall element according to claim 1, wherein a magnetic focusing chip is provided on the magneto-sensitive surface of the pellet. 3. The internal structure of the Hall element is arranged in this order from the substrate side to the lead frame, the pellet, the magneto-sensitive surface, and the magnetic focusing chip, and receives a magnetic flux from the magnetic focusing chip side. The Hall element according to claim 2, wherein the Hall element has a form.