JP2711116B2 - Magnetoresistive element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a magnetoresistive element which is a kind of magnetoelectric conversion element.

(Prior art)

A magnetoelectric conversion element utilizing the magnetoresistance effect (hereinafter referred to as a magnetoresistance element) is well known in Japanese Patent Application Laid-Open No. 50-28989.

Specifically, this type of magnetoresistive element is shown in FIG.
Some have a structure as shown in FIG. In this method, a thin-film resistor pattern 3 made of a ferromagnetic material and a plurality of electrodes 4 made of a conductive material are formed on a surface 2 of a flat insulating substrate 1 made of glass, silicon wafer, sapphire or ceramic. And a lead frame 5 wire-bonded to the electrode 4 with a fine wire 8 of gold or aluminum. The electrode 4 is a resistor pattern 3
And three lead frames 5 are provided corresponding to these electrodes 4. 9 is a plastic molding.

FIG. 7A shows a specific structure of the magnetoresistive element.
(B) Other than the above, there is also a flip-chip type which does not have a lead frame and is directly soldered (reflow soldered) to a printed wiring board.

[Problems to be solved by the present invention]

Recently, a magnetoresistive element is mounted on a surface of a printed wiring board or a thick-film printed circuit board (hereinafter, referred to as a circuit board) by a surface mounting technique for convenience in detecting magnetism. There has been a demand for mounting the device with the surface having a vertical position. This requirement is common when used for detecting a rotating magnet or the like.

Among the prior arts, in the former, not only the shape of the magnetoresistive element is large, but also when mounting on a printed wiring board, a lead frame is bent or the bent end of the lead frame is inserted into a hole of a printed wiring board. However, there is a problem that assembly such as a bending process and a drilling process is troublesome and cost increases.

Among the conventional techniques, the latter is such that when the temperature change is large, the electrodes are destroyed due to the strain applied to the soldered portion due to the difference in thermal expansion coefficient between the substrate 1 of the magnetoresistive element and the printed wiring board, There was a problem that the electrical connection between the electrode and the printed wiring board was broken.

Therefore, an object of the present invention is to provide a small-sized magnetoresistive element that is easy to be surface-mounted perpendicular to the surface of a circuit board, and that maintains an electrical connection with the circuit board reliably even when subjected to a temperature change. The idea is to propose a device.

[Means for solving the problem]

In order to achieve the above object, in a magnetoresistive element according to the present invention, an electrode and a lead frame are connected by solder, the lead frame is a clip lead frame sandwiching the substrate, and the lead frame is located at an end of the substrate. Is characterized by projecting outward from the front surface and the back surface of the substrate at right angles to each other.

If the corner of the board to be inserted into the lead frame is chamfered to about 45 degrees, it is effective in assembling the board and the lead frame.

[Action]

When the magnetoresistive element configured as described above is surface-mounted on a circuit board, the lead frame projects outward at right angles from the front and back surfaces of the element. The element is free standing on the surface of the circuit board. Then, the surface of the magnetoresistive element having the resistor pattern is vertically arranged on the circuit board. Also, even if the temperature changes in the mounted state and stress distortion occurs due to the difference in the coefficient of thermal expansion between the substrate of the magnetoresistive element and the circuit board, the solder and the lead frame connecting the electrode and the lead frame may have mechanical stress. To prevent destruction of electrodes and connections.

〔Example〕

1 (A) and 1 (B), reference numeral 1 denotes an insulating substrate made of glass or the like, and on its surface 2, a resistor pattern 3 made of a ferromagnetic magnetoresistive material and three electrodes 4 made of a conductive material are formed. Have been. Numeral 5 is a lead frame, and each of them sandwiches the substrate 1 with a clip lead frame. The lead frame 5 and the electrode 4 are soldered with a material which is flexible and can make an electrical connection reliably. Reference numeral 10 indicates solder for this purpose. or. Reference numerals 5a and 5a denote projecting portions of the lead frame 5, which project outward at right angles from the front surface 2 and the rear surface 7 of the substrate 1 at the end 6 of the substrate 1.

In the embodiment shown in FIG. 2, the shape of the lead frame is different from that of the embodiment shown in FIG.
As shown by reference numeral 11 in (D), a chamfer of about 45 degrees is formed, and insertion into a lead frame is easy.

FIGS. 3A and 3B show a lead frame used in the embodiment shown in FIG. 1, and shows a shape when a large number of the lead frames are continuous. With this lead frame (clip lead frame), the substrate of the magnetoresistive element is sandwiched from the front and back by the electrode part and held, and this is immersed in a molten solder bath to solder-connect the electrode and the lead frame. Cut off the parts.

The lead frame is manufactured at low cost by continuously cutting and bending a long ribbon-like thin film, similarly to the one conventionally used for connecting a thick film printed circuit. The lead frame is preferably made of an elastic material such as a phosphor bronze plate, and its surface is preferably plated with tin or a tin-lead alloy to improve solderability.

FIG. 4 shows a long state of the lead frame used in the example of FIG.

FIGS. 5 (A) and 5 (B) show the molding of the lead frame 5 in FIGS. 1 (A) and 1 (B) by plastic molding with a plastic such as epoxy resin, as indicated by reference numeral 9 except for the protruding portion 5a. This is an example. In FIG. 5 (B),
Although the state in which the magnetoresistive element is mounted on the surface of the circuit board 12 is shown, the projecting portion 5a of the lead frame 5 acts to make the element stand on the circuit board 12. In this embodiment, the resistor pattern 3 can be located closest to the circuit board 12 as in the case of FIG.
This is convenient when placed close to the back surface of the twelve.

6 (A), (B), and (C) also include a plastic molding 9, which is the same as the embodiment of FIG. 5 as compared with the embodiment of FIGS. 1 and 2. In addition, the reliability of the electrical connection between the electrode and the lead frame is improved, the handling of the element is facilitated, and the automatic mounting of the assembly is facilitated.

In the above embodiment, the electrode 4 is formed only on one surface of the substrate on which the resistor pattern 3 is formed. However, if this electrode is extended to the side surface or the back surface of the substrate 1, the strength of the electrode increases.

Needless to say, a surface protection film such as a passivation film is provided on the magnetoresistive element.

〔The invention's effect〕

When the magnetoresistive element is surface-mounted on the circuit board, the surface on which the resistor pattern of the magnetoresistive element is formed is positioned vertically on the circuit board surface and is self-supporting. You can use the soldering method,
Assembly costs are reduced. In addition, since the entire device can be reduced in size, the mounting density can be increased. Further, since the lead frame and the solder absorb the stress due to mechanical vibration and thermal strain, the reliability of the electrical connection is improved.

Also, the soldering between the clip lead frame and the electrode
By immersing in a solder bath, a large number of magnetoresistive elements can be continuously soldered, so that the assembly cost is reduced and the cost of the magnetoresistive elements is reduced.

[Brief description of the drawings]

1 (A) and 1 (B) are front and side views of an embodiment of the present invention, and FIGS. 2 (A), (B), (C) and (D) are plan views of another embodiment. Front view, side view and a partially enlarged view of the board,
3 (A) and 3 (B) are plan views of a continuous clip lead frame, FIG. 3 (A) is a sectional view taken along the line AA, and FIGS. 4 (A) and 4 (B) are clips of other shapes. FIGS. 5 (A) and (B) are a front view and a side view of still another embodiment, and FIGS. 6 (A), (B),
(C) is a plan view, a front view, and a side view of still another embodiment;
FIGS. 7A and 7B are a front view and a side view of the prior art. 1 ... substrate, 2 ... surface, 3 ... resistor pattern, 4 ...
... Electrode, 5 ... Lead frame, 6 ... End, 7 ... Back, 11 ... Chamfer

Claims (2)

(57) [Claims] 1. A surface (2) of an insulating substrate (1) such as glass.
It has a resistor pattern (3) made of a ferromagnetic magnetoresistive material formed thereon, an electrode (4) made of a conductive material, and a lead frame (5) electrically connected to the electrode (4). In the magnetoresistive element, a lead frame (5) is a clip lead frame sandwiching the substrate (1);
The electrode (4) and the lead frame (5) are connected by solder, and the lead frame (5) is connected to the end (6) of the substrate (1) so that the magnetoresistive element can stand on the circuit substrate. 3. The magnetoresistive element according to claim 1, wherein the magnetoresistive element protrudes outward from the front surface (2) and the back surface (7) of the substrate (1) at right angles. 2. The magnetoresistive element according to claim 1, wherein a corner of the substrate inserted into the lead frame is chamfered.