JPH0342497B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to compound semiconductor devices such as Hall elements and magnetoresistive elements.

(b) Conventional technology Compound semiconductors with high carrier mobility, such as indium antimonide (InSb) and indium arsenide (InAs), have the property that their resistance value changes when magnetism is applied to them. Magnetic detectors using this type of compound semiconductor device have been put into practical use.

FIG. 3 is a front sectional view showing a general configuration of a magnetic detector using the above-described compound semiconductor device, and 21 in the figure indicates a housing. The housing 21 is a plastic molded product, and an opening 21a formed on the top surface is closed with a protective plate 22 made of a beryllium-copper thin film. The protective plate 22 is the housing 2
1, and its outer surface is chrome plated as necessary to improve wear resistance.

As shown in FIG. 4, a detector main body 20 made of a compound semiconductor device is disposed within the casing 21 with a suitable gap between the protective plate 22 and the detector main body 20 . The detector main body 20 is composed of a sensor unit 23, a mount board 28, a permanent magnet 29, and the like.
The sensor unit 23 has magnetoresistive elements 26 and 27 made of compound semiconductor elements such as indium antimonide that are electrically connected to each other on a thick magnetic substrate 24 made of ferrite, which are arranged side by side using an adhesive resin 25. This magnetic substrate 24 is made of a thinner plastic mount substrate 2.
It is fitted into a hole 28a drilled in 8. In this state, the lower surface of the magnetic substrate 24 is attached to the mount substrate 28.
The bottom plate 2 is separated by the phosphor bronze bottom plate 28' on the lower surface.
8' faces a cylindrical bias permanent magnet 29 with one magnetic pole end fixed to the lower surface, and both magnetic resistance elements 26 and 27 on both sides are positioned higher than the upper surface of the mount board 28 by a required dimension. ing. The sensor unit 23 is mounted on the mount board 28.
An annular space 30 is provided which surrounds the spacer and whose upper surface is higher than the surfaces of the magnetoresistive elements 26 and 27, and the upper surface of the spacer 30 is brought into contact with the periphery of the protection plate 22 to connect the protection plate 22 and the magnetoresistive elements. 26,2
7 is set to a predetermined value. The electrodes of each magnetoresistive element 26, 27 and one end of the printed wiring 28b on the mount board 28 are connected using a plurality of gold wire conductive wires 31a, 31b (only two are shown in the drawing). The other end of the printed wiring 28b is connected to one end of the lead wires 32a, 32b, and 32c at the peripheral edge of the mount board 28. These lead wires 32a, 3
The other ends of 2b and 32c are plastic lid members 3.
3 are connected to lead plates 34a, 34b, and 34c extending through the lead plate 3.

By the way, in conventional various transistors and IC products, pellets, that is, electrodes on the element side, stems,
In other words, a gold wire is used to connect the lead plate on the board side, and for the pellet side, the end of the gold wire is melted into a ball shape, and this is pressed to the electrode and glued in the shape of a nail head. In addition, it is common to heat and press the end of a gold wire to the lead plate on the board side, so-called stay bonding.In magnetic detectors, the lead wire is also attached to the pellet side. Nail head bonding is performed for the electrodes of a certain magnetoresistive element, and stitch bonding is performed for the printed wiring on the substrate side.

However, in the case of the above-mentioned magnetic detector, its sensitivity is limited to the detector body 20, especially its magnetoresistive element 2.
6, 27 and the test object, and it is desirable to make this as small as possible in order to improve sensitivity. Therefore, the thickness of the protective plate 22 should be as small as possible. It is desirable that the protective plate 22 be thin and that the distance between the protective plate 22 and the surfaces of the magnetoresistive elements 26 and 27 be as small as possible. However, if the above-mentioned nail head bonding method is adopted, the part where the nail head part and the gold wire part are connected, that is, the neck part, may break if bent weakly.
The gold wire part connected to the nail head part needs to be raised upward by the required dimension and bent at the middle of the gold wire part. Therefore, the conductors 31a, 31b and the protective plate 2
To avoid contact with 2, magnetoresistive elements 26, 27
A predetermined distance must be left between the magnetic detector and the inner surface of the protective plate 22, and there is a limit to how short the distance can be shortened, which is a major obstacle in improving the sensitivity of the magnetic detector.

Therefore, in order to eliminate the above-mentioned drawbacks, the present applicant proposed a detector main body 20 made of a compound semiconductor device including a plurality of magnetoresistive elements 26, 27 and a substrate 24 for fixing them, as shown in FIG. In the magnetic detector having the magnetoresistive element 26,
27 electrode and the wiring part 28b on the mount board 28
The ends of the conductive wires 31a' and 31b' on the wiring part side are nail-head bonded to the wiring part 28b, and the conductive wires 31a' and 31b' are connected to the magnetoresistive element 2.
By stitch bonding on 6,27,
The magnetic detector is the opposite of the conventional nail head bond method, and the distance between the surfaces of the magnetoresistive elements 26 and 27 and the object to be measured is significantly shortened, thereby significantly improving detection sensitivity. (1987)
−For details on issue 166690. ) (C) Problems to be Solved by the Invention However, in the method of static bonding the conductive wires 31a' and 31b' onto the magnetoresistive elements 26 and 27, the magnetoresistive elements 26 and 27 are formed of a fragile compound semiconductor. Due to the nature of the magneto-resistance elements 26 and 27, cracks are likely to occur inside the magnetoresistive elements 26 and 27 due to the stress of thermocompression bonding during staple bonding, causing wire breakage and noise defects.
It is also possible to extend the electrodes on the adhesive resin 25 and perform stitch bonding on the adhesive resin 25 to prevent stress from being applied to the magnetoresistive elements 26 and 27. Since the electrode 25 is soft, sufficient pressure cannot be applied, resulting in poor connection between the electrode and the conductive wires 31a' and 31b'.

(d) Means for solving the problem The present invention has been made to solve the above-mentioned problems, and includes extending the lead electrode of the compound semiconductor element to the adhesive resin that fixes the compound semiconductor element to the substrate. In addition, a protective film made of a silicon compound is provided between at least the electrode and the adhesive resin.

(E) Effect In the present invention, by disposing a silicon compound filter between at least the electrode and the adhesive resin, the electrode extending on the adhesive resin and the conductive wire can be firmly connected.

(F) Embodiments The present invention will be described below with reference to drawings showing embodiments thereof.

FIG. 1 is an enlarged sectional view of a main body portion of a magnetic detector using a compound semiconductor device according to the present invention. The detector main body 20 is composed of a sensor unit 23 made of a compound semiconductor device, a mount substrate 28, a permanent magnet 29, and the like. Sensor unit 2
3, magnetoresistive elements 26 and 27 made of compound semiconductor elements such as indium antimonide are electrically connected to each other on a thick magnetic substrate 24 made of ferrite, and are arranged side by side using adhesive resin 25. Ru. Further, lead electrodes 40 and 41 extending to the adhesive resin 25 are provided on the magnetoresistive elements 26 and 27. The present invention also provides extraction electrodes 40, 4.
A protective film 42 made of a silicon compound such as silicon oxide nitride is provided between the adhesive resin 25 and the adhesive resin 25 .

The magnetic substrate 24 of the sensor unit 23 constructed in this way is fitted into a hole 28a formed in a thinner plastic mount substrate 28 and fixed. In this state, the lower surface of the magnetic substrate 24 faces the permanent magnet 29 for bias via the phosphor bronze bottom plate 28 on the lower surface of the mount substrate 28, and the magnetoresistive elements 26 and 27 on the upper surface are opposed to the phosphor bronze bottom plate 28 on the lower surface of the mount substrate 28. It is located higher than the required dimensions. A printed wiring 28b is provided around the hole 28a on the mount board 28, and an annular spacer that surrounds the sensor unit 23 and is higher than the magnetic resistance elements 26 and 27 is provided on the upper surface of the periphery. By bringing the upper surface of the spacer into contact with the periphery of the protection plate 22, the distance between the protection plate 22 and the magnetoresistive elements 26, 27 is set to a predetermined value.

One end 31c' of the conductive wire 31a', 31b' connects the electrode of each magnetoresistive element 26, 27 and one end of the printed wiring 28b on the upper surface of the mount board 28;
31c' is nail head bonded to one end of the printed wiring 28b, contrary to the conventional case shown in FIGS. 3 and 4, and the ends 31d', 31
d′ is the extraction electrode 40 of the magnetoresistive elements 26, 27;
It is state bonded to 41.

In this way, the adhesive resin 25 and the extraction electrode 4
0 and 41, a protective film 42 is interposed between them. Therefore, the electrodes 40, 41 on the adhesive resin 25
When stitch-bonding the conductors 31a' and 31, sufficient pressure can be applied because the bonding part is made firm by the protective film 42.
b' can be connected to the electrodes 40, 41 with sufficient adhesive strength. Moreover, since no stress is applied to the magnetoresistive elements 26 and 27, there is no risk of cracks occurring.

Next, an example of a method for manufacturing the sensor unit 23 according to the present invention will be briefly explained with reference to FIG.

A photoresist pattern 51 is formed on a compound semiconductor piece 50 such as indium antimonide (FIG. 2A). The semiconductor piece 50 is etched and dug to a certain depth (FIG. 2B). and,
The photoresist is removed and a protective film 42 made of silicon oxide or silicon nitride is applied.
It is formed by CVD method etc. (Figure 2 C). The semiconductor piece 50 is attached to the substrate 24 using adhesive resin 25 (FIG. 2D). Thereafter, the back surface of the semiconductor piece 50 is polished to a uniform thickness to form magnetoresistive elements 26 and 27 made of compound semiconductor elements (FIG. 2(e)). Thereafter, the sensor unit 23 is formed by providing lead electrodes 40, 41 extending to the adhesive resin 25 on the magnetoresistive elements 26, 27.

In this embodiment, the substrate 24 and the magnetoresistive element 2
A protective film 42 is also provided between 6 and 27, but it may be removed if necessary.

(G) Effects of the Invention As explained above, in the present invention, since a silicon compound is disposed between at least the electrode and the adhesive resin, it is difficult to bond the conductive wire to the electrode extending on the adhesive resin. Sufficient pressure can be applied and the conductive wire can be bonded to the electrode with sufficient adhesive force, and since stress is not applied to compound semiconductor elements such as magnetoresistive elements, there is no risk of cracking.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view of a main part of a magnetic detector using the compound semiconductor device of the present invention, and FIG. 2 is a process diagram showing an example of a method for manufacturing the compound semiconductor device of the present invention. 3 to 5 show a magnetic detector using a conventional compound semiconductor device, in which FIG. 3 is a front sectional view, and FIGS. 4 and 5 are enlarged sectional views of main parts. 24...Substrate, 25...Adhesive resin, 26,2
7... Magnetoresistive element made of a compound semiconductor element,
40, 41...Extraction electrode, 42...Protective film.

Claims (1)

[Claims] 1. In a compound semiconductor device in which a compound semiconductor element is fixed to a substrate with an adhesive resin, an extraction electrode of the compound semiconductor element is provided to extend onto the adhesive resin, and at least a gap between the electrode and the surface of the adhesive resin is provided. 1. A compound semiconductor device characterized in that a protective film made of a silicon compound is disposed on the surface of the semiconductor device.