JPS61295679A - Magnetic sensor - Google Patents

Abstract

PURPOSE:To obtain a magnetic sensor enabling the disposition of an MR chip in proximity to a surface whereon fitting is to be made, by a method wherein a holder is molded integrally with terminals of a lead frame by using resin, the MR chip is stuck on this holder and chip electrodes and the terminals of the lead frame are connected together. CONSTITUTION:A holder 11 is molded integrally with terminals 12, 12, ... of a lead frame by using resin. An MR chip 1 is stuck on the holder 11 by a bonding agent or the like, and chip electrodes 1a, 1a, ... and the frame terminals 12, 12, ... are connected together by wire-bonding. According to the above- described structure, the mechanical strength between the frame terminals 12, 12, ... and the MR chip 1 is given mainly by the holder 11 with the frame terminals itself, not depending on bonding resin 13, and therefore the strength can be further improved. In addition, the MR chip 1 needs only to be stuck, as it is, on the holder 11 without fitting a member for an external circuit connection, and thus it turns easy to handle.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a magnetic sensor including an MR chip formed into an element by a ferromagnetic thin film on the surface of a substrate.

<Summary of the Invention> A holder for fixing the MR chip is integrally molded with resin together with terminals made of a lead frame, and the terminals of the lead frame are integrated and incorporated into the holder. Connect the chip electrode and the terminal of the lead frame with the MR
The chip is placed close to the surface of the holder to which Jtfu is attached, making it possible to reduce the thickness of rotors for magnetic detection.

<Prior Art> FIG. 6 is an exploded perspective view showing a conventional example. MR chip 1
is made by forming a ferromagnetic thin film of nickel cobalt, nickel iron, etc. on the surface of a substrate (one side on the left in the figure) made of glass, silicon, ferrite, etc., and has lead wires 2, 2 . . . for connecting chip electrodes and external circuits. ... are connected by soldering, welding, etc. The resin 3 is a resin for reinforcing and protecting the connection portion.

With the wires connected and coated with resin in this way, the MR chip l is attached to the holder 4 which has been made of resin or molded in advance.
It is used as a detection sensor for signals for controlling the rotation of cabstan motors in VTRs, audio equipment, and other tape equipment.

Figure 7 shows an example of implementation. The magnetic scale 5 for rotation control is
The above-mentioned magnetic sensor 6 is disposed near the magnetic scale 5, which is magnetized at even pitches around the outer periphery of the rotor portion of the capstan motor.

The magnetic sensor 6 is arranged as follows. First, with the rotor being rotated by the motor drive coil 7, bring the magnetic sensor 6 near the magnetic scale 5, select a position so that a good electric signal can be obtained, and then use the screw 8 to Tighten and fix to the steel board 9. Note that the lead wires 2, 2. The lead wires 2, 2, . The above-mentioned adjustment is performed depending on the length with sufficient margin.

<Problems to be Solved by the Invention> Incidentally, recently, lighter, thinner, shorter and smaller devices such as 8 IuV TR have been proposed, and there is a demand for reducing the distance between the rotor and the iron substrate 9. However, in the conventional magnetic sensor, the lead wires 2, 2°, etc. side ends of the MR chip 1 are exposed, making it difficult to arrange the MR chip 1 close to the iron substrate 9. In addition, lead wires 2, 2. ...and MR
The mechanical strength between the chips 1 depends only on the reinforcing and protective resin 3, and there are limits to the improvement of the wiring. The present invention solves the above-mentioned conventional drawbacks.

Means for Solving the Problems> A lead frame is used as a member for connecting the external circuit of the MR chip. The holder is integrally molded from resin together with the terminals of the lead frame, and has a structure in which the MR chip is pasted on the holder and the chip electrodes and the terminals of the lead frame are connected.

Function: Since the terminals of the lead frame are integrated into the holder, the mechanical strength is mainly provided by the holder itself, and the wire connection end of the MR chip is not exposed to the outside and is placed on the holder by the holder. It can be easily placed close to the numbering surface.

<Embodiment> FIG. 1 is a perspective view showing an embodiment of the present invention, and FIG. 2 is an enlarged perspective view of the main part thereof. Note that FIG. 2 is partially cut away for ease of understanding.

The holder 11 holds the lead frame terminals 12゜12, ・
... It is integrally molded with resin.

For example, this is a well-known method known as transfer molding, in which a lead frame to be sealed is set, the mold is closed, resin preheated with a high-frequency preheater is poured into a pot, and the resin is pressurized and injected with a plunger. It can be easily produced by a molding method in which a cavity is filled and hardened.

That is, here, 7 frame terminals +2.12. ... is constructed by being incorporated into the holder l] from the beginning.

The MR chip 1 is pasted on this holder II with adhesive or the like, and the chip electrodes 1 al 121... and the frame terminals +2, 12, . . . ...Connect between them by wire bonding.

Note that the connection is made using the frame terminal 12. +2. . . . and the chip electrodes 1alla . . . may be overlapped and soldered. The resin 13 is hardened by botting to protect this part. Further, as clearly shown in FIG. 1, a holder for attaching an external device is integrated into the holder 11. That is, the frame terminal 12
．． +2. When the holder 11 is integrally molded with resin, it is shaped to be convenient for attachment to an external device, and the mounting holes 1 are provided for screws, etc.
4.14 has been established.

With the above structure, the frame terminal +2.12. ...and M
The mechanical strength between the R tips 1 is mainly provided by the frame terminal holder 11 itself, and the botting resin 13 is sufficient to protect the wire. In this way, the mechanical strength does not depend on the potting resin I3, and the strength can be further improved compared to conventional products. The holder 11 also has frame terminals +2.12. In addition, the MR chip 1 is simply attached to the holder 11 as a chip without attaching an external circuit connection member, so it is less susceptible to physical impact force. Nevertheless, it also has the advantage of being easy to handle.

FIG. 3 shows an example of mounting the magnetic sensor according to this embodiment. A magnetic sensor 6A shown in FIG. 1 is fixed to an iron substrate 9 with screws 8 on the side surface of the magnetic scale 5, and a frame terminal 12 is soldered to the back surface of the iron substrate 9.

In this way, the MR chip 1 can be easily placed on the holder II in close proximity to the iron substrate 9 without exposing the wire connection side end of the MR chip 1 to the outside due to the holder 11. It can fully cope with the miniaturization of the light, thin, and short.

FIG. 4 shows another embodiment of the above-mentioned integral molding, in which the terminals +2.12. of the holder I+ are molded during molding. ... A protrusion 15.15 is integrally provided at the other end on the opposite side. Fifth
The figure shows an example of mounting this magnetic sensor 6B. This magnetic sensor? -6B can be further applied to an ultra-thin motor as shown in FIG. Specifically, the sensor fixing holes 16 + 16 VC- provided on the iron substrate 9 are fixed with the protrusions 15.15 of the holder 11 depressed, and the frame terminals +2.12. ... is bent and connected to the pattern on the upper surface of the iron board 9. Terminal 12. +2.・
As described above, the bending of the holder 11 can be performed without any problem due to the increased mechanical strength of the holder 11 itself.

<Effects of the Invention> As described above, the present invention can provide a useful magnetic sensor in which an MR chip can be disposed close to the surface to which it is attached.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing one embodiment of the present invention, FIG. 2 is an enlarged perspective view of the main part with a part cut away, FIG. 3 is a side view showing an example of implementation, and FIG. Perspective view showing the embodiment, No. 5
6 is an exploded perspective view showing a conventional example, and FIG. 7 is a side view showing an example of implementation. I...MR chip, 11...Holder, +2...
Frame terminal, 13...Resin, I4...Mounting hole. Agent Patent Attorney Aihiko Fuku (and 2 others) Figure 3 Figure 4 Figure 6 Figure 7

Claims (1)

[Claims] 1. A holder is integrally molded with resin, and the terminals of the lead frame are incorporated and fixed into the resin at the same time as the integral molding, and an MR chip whose element is formed from a ferromagnetic thin film on the surface of the substrate is attached to the holder. and connect the electrodes of the MR chip and the terminals made of the lead frame on the holder, and the MR chip is arranged on the holder in close proximity to the mounting surface of the holder. A magnetic sensor characterized by: