JPS60123782A - Ferromagnetic thin film magnetic resistance sensor - Google Patents

Abstract

PURPOSE:To make it possible to limit the flowing out amount of a reinforcing resin from a sensor part, by directly soldering the chip of a sensor and an external wiring substrate having a wiring pattern preliminarily formed thereto. CONSTITUTION:A chip is constituted by providing a ferromagnetic resistance thin film 12 and two layers of passivation films 13, 14 on a glass substrate 11. Now, a flexible substrate 15 or a rigid substrate 16 having a wiring pattern preliminarily formed thereto is used as an external wiring substrate and the chip and these wiring patterns are directly soldered. Herein, by coating only the single sides of the substrates 15, 16 with a reinforcing resin 18, the flowing out amount of the reinforcing resin 18 is limited and reinforcement is enabled without losing a thin structure.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a ferromagnetic thin film magnetoresistive sensor, and particularly to its chip assembly structure.

<Prior art> Conventionally, as a chip assembly method for a ferromagnetic thin film magnetoresistive sensor (hereinafter referred to as an MR sensor), an assembly method using a known transfer molding technique or an assembly method in which lead wires are soldered directly to an MR chip have been used. It will be done. However, in these assembled structures, the amount of protrusion from the MR section is large, so the MR sensor with this structure
The device structure is extremely unsuitable for use in sensors that require the R section to be as close to the magnetic medium as possible, such as for detecting FG signals of VTR capstan motors and magnetic phone coders.

FIG. 1 is a cross-sectional view of an MR sensor in which lead wires are directly soldered to the MR chip.

The MR chip has a ferromagnetic magnetoresistive thin film 2 on a glass substrate 1.
and passivation film 3 are formed, and this M'
Lead wires 4 are soldered directly to the R chip. The lead wire 4 is made of a conductor having a diameter of 6 cm, for example, and a plurality of lead wires 4 are soldered to the MR chip. The shaded part 5t/'i soldering in the figure shows the entire part, and the soldering part 6 made of epoxy resin is molded to reinforce the part 5.

Since each lead wire 4 with a large diameter is soldered in this way, the amount of protrusion from the MRm is
, the lead wire 4, and the soldering thickness are the total thickness of the epoxy resin 6 for reinforcing the part. Furthermore, the epoxy resin 6 for reinforcing the soldering part protrudes greatly from the bottom of the glass substrate 1.

<Object of the Invention> In view of the above points, the Kinoto F3A provides a chip assembly structure of an M'R sensor that suppresses the amount of protrusion from the M'Rfa.

<Embodiments> FIGS. 2 and 3 show cross-sectional views of MR sensors according to embodiments of the present invention.

The MR chip is constructed by forming on a glass substrate 11 a ferromagnetic magnetoresistive thin film 12, an eleventh film, and here a second Vanvation film 13, 14.

The external wiring board may be a flexible board 15 (FIG. 2) on which a wiring pattern is formed in advance or a rigid board 1.
6 (FIG. 3) are used, and the MR chip is directly soldered to these wiring patterns.

The amount of protrusion from the MR section is the maximum, and the soldering is the sum of the thickness of 17 and the thickness of the soldered board base material (flexible board 15, rigid board 16), which is extremely thin.

Further, in order to reinforce the soldered parts of the soldered boards 15 and 16, reinforcing epoxy resin IEI is applied to only one side of the boards 15 and 16. The amount of resin 18 required is extremely small, unlike the conventional method for reinforcing each lead wire 4, which is soldered one by one. The thickness of the resin 18 can be kept within the thickness of the MR chip, and plays the role of reinforcing the thin structure without damaging the thin structure. 11'f: was used, but a similar thin structure is also possible using silicon, alumina, ferrite, etc.0 <Effects of the Invention> As described above, the present invention has a simple structure and is suitable for jumping out from MR cities. We can provide a useful MR sensor with a reduced amount.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a conventional structure, Fig. 2 is a sectional view showing a structural example of an embodiment of the present invention, and Fig. 3 is a sectional view showing a structural example of another embodiment of the present invention. . . . Glass substrate, 12 . . . Ferromagnetic magnetoresistive thin film, 15 . . . Flexible substrate, 16 . Agent Patent attorney Aihiko Fukushi (2 others) Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] ■, M'R with a ferromagnetic magnetoresistive thin film formed on the holding substrate
The chip is directly soldered to an external wiring board on which a wiring pattern has been formed in advance, and a reinforcing resin is applied to only one side of the external wiring board before soldering. Ferromagnetic thin film magnetoresistive sensor 0