JP2000030908A - Thermistor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermistor element which can secure the electrical connection with lead terminals, even when thermal stresses are applied to the element. SOLUTION: A thermistor element is provided with an elemental thermistor body 11 having two flat surfaces, at least two lead terminals 12a and 12b which are respectively electrically connected to one surface of the elemental body 11 by using a metallic wire 13 and to the other surface by using at least one or more Au or Ag bumps 15, and a coating layer 14 which covers the elemental body 11, wire 13, bumps 15, and parts of the lead terminals 12a and 12b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermistor element used for electronic components for detecting and compensating for temperature, for example.

[0002]

2. Description of the Related Art FIGS. 7 and 8 are a side sectional view and a front view of a conventional thermistor element, respectively. In a conventional thermistor element, lead terminals 121a are electrically connected to both surfaces of a plate-like thermistor body 111 having electrodes formed on both sides by using solder 123, and then the thermistor body 111 and the lead terminals 121a are connected with resin 122 or the like. Some were coated.

[0003]

According to this configuration, when thermal stress is repeatedly applied to the thermistor element, cracks are gradually generated in the solder 123 due to thermal fatigue, and the lead terminal 121a eventually comes off from the thermistor body 111. There was a problem that electrical connection could not be secured.

Accordingly, an object of the present invention is to provide a thermistor element capable of securing electrical connection between a thermistor element and a lead terminal even when a thermal stress is applied.

[0005]

In order to achieve this object, a thermistor element of the present invention uses a thermistor element having two planes and a wire made of metal on one surface of the thermistor element. At least two lead terminals electrically connected using at least one bump made of Au or Ag on the other surface, the thermistor body, the wires, the bumps, and a part of the lead terminals. The above object can be achieved because even if a thermal stress is applied to the thermistor element, the thermal stress can be buffered by wires and bumps.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention provides a thermistor body having two planes, a metal wire on one surface of the thermistor body, and at least a metal wire on the other surface. At least two lead terminals electrically connected by using one or more Au or Ag bumps, a coating covering the thermistor body, the metal wires, the bumps, and a part of the lead terminals. A thermistor element having a layer and can secure electrical connection between the thermistor element and the lead terminal even when thermal stress is applied.

According to a second aspect of the present invention, there is provided a thermistor body having two planes, a metal wire on one surface of the thermistor body, and a uniform thickness of 1 to 15 μm on the other surface. At least two lead terminals electrically connected using the solder layer, the thermistor element, the wire, the solder layer, and a coating layer that covers a part of the lead terminal. The layer is a thermistor element having a size equal to or smaller than the bonding surface between the thermistor element and the lead terminal, and can secure electrical connection between the thermistor element and the lead terminal even when thermal stress is applied. Things.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. (Embodiment 1) FIG. 1 is a side sectional view of a thermistor element according to the present embodiment, and FIG. 2 is a front view.

FIG. 3 is a top view of a lead terminal on which bumps are formed, and FIG. 4 is a top view of the thermistor element before a covering layer is formed.

Hereinafter, a method for manufacturing a thermistor element will be described. First, a lead terminal 1 having a square plate-like negative characteristic thermistor element 11 provided with electrodes on both surfaces and a flat support portion 121 for supporting the thermistor element 11 at the tip end.
The bumps 15 made of Au or Ag are electrically connected to the 2a by a method such as thermocompression bonding or ultrasonic thermocompression bonding.
As described above, the flat supporting portion 1 is provided at the tip of the lead terminal 12a.
The provision of 21 enables stable connection of the thermistor body 11 and subsequent connection of the wire 13 via the bump 15.

The electrodes of the thermistor body 11 are Au,
Ag, Pd, Pt, Ag-Pd, Ag-Pt, Ag-A
The paste is formed by printing, baking, vapor deposition, sputtering, or the like using any material of u, Au-Pt, and Au-Pd.

Also, as shown in FIG.
a, a diameter of 10 to 50 μm and a height of 10 to
Although five 50 μm bumps 15 are provided, the number is not particularly limited. However, in consideration of stability when connecting the thermistor body 11 to the lead terminal 12a, it is preferable to provide three or more bumps 15. Furthermore,
When a plurality of bumps 15 are provided, it is necessary to arrange them in a balanced manner so that the thermistor body 11 can be stably supported.

Next, as shown in FIG.
1 and the L-shaped lead terminal 12b
They were electrically connected via wires 13 made of u or Al. Here, as a material of the lead terminals 12a and 12b, a Fe-based or Cu-based material is used, and at least a surface of the lead terminal 12a connected to the bump 15 and a surface of a portion connected to the wire 13 of the lead terminal 12b are provided. A
One of u, Ag, and Pd is plated. Also,
The reason why the L-shaped lead terminal 12b is used is that even if a force in the pull-out direction or the crotch direction is applied to the lead terminal 12b of the thermistor element shown in FIG. 1 and FIG. This is to prevent it from falling out.

Next, the thermistor body 11 and the bump 15
In addition, the wire 13 and a part of the lead terminals 12a and 12b are coated with an epoxy or phenol resin or glass to form a coating layer 14 having an insulating property to obtain a thermistor element as shown in FIGS. . Although the lead terminals 12a and 12b are not shown in FIG. 4, the lower end of FIG. 1 and FIG.

At this time, it is preferable that the material used for the covering layer 14 has a smaller linear expansion coefficient than the wire 13 and the bump 15.

The thermistor element according to the first embodiment obtained by the above-described method has the wires 13 and bumps 15 used to connect the thermistor body 11 and the lead terminals 12a and 12b even when heating and cooling are repeatedly applied. Is suppressed and the applied thermal stress is relieved by the wires 13 and the bumps 15, so that electrical connection between the thermistor element 11 and the lead terminals 12a and 12b can be ensured.

(Embodiment 2) FIG. 5 is a side sectional view of a thermistor element according to the present embodiment, and FIG. 6 is a top view of a lead terminal on which a solder layer is formed. The difference from the thermistor element in the first embodiment is that the thermistor element 1
1 and the lead terminals 12a are connected via a thin solder layer 16 having a thickness of 1 to 15 μm instead of using the bumps 15. Thermistor body 11 and lead terminal 12
a are connected by the method described below to obtain the thermistor element in the present embodiment.

First, the thermistor body 11 is connected to the lead terminal 1.
The method of connecting to 2a is to apply cream solder thinly and uniformly to the support of the lead terminal 12a by printing or transfer dispensing, and then install the thermistor body 11 thereon.
At that time, as shown in FIG.
When the thermistor body 11 is connected, it does not protrude from the supporting portion 121 of the 2a and prevents the resistance from changing due to the solder wrapping around the side surface of the thermistor body 11. Next, this is heated to connect the thermistor body 11 to the lead terminal 1.
The support portion 2a is electrically connected via a thin solder layer 16. The subsequent method of electrically connecting the thermistor body 11 and the lead terminal 12b by the wire 13 and the method of forming the covering layer 14 use the same method as that of the thermistor element of the first embodiment.

The thermistor element of the present embodiment obtained by the above-described method has the same structure as that of the thermistor element of the first embodiment, even if heating and cooling are repeatedly applied, to the connection between the thermistor element 11 and the lead terminals 12a and 12b. The thermal stress applied to the wire 13 and the thin solder layer 16 used in the process is suppressed, the thermal stress applied to the wire 13 is reduced, and the thermistor element is formed using the thin solder layer 16 having a uniform thickness of 1 to 15 μm. Since the body 11 and the lead terminals 12a are connected, the shape change due to the thermal expansion of the solder layer 16 is small, and cracking and peeling of the thermistor body 11 and the thin solder layer 16 itself are suppressed.

[0020]

As described above, according to the thermistor element of the present invention, even if a thermal stress is applied to the thermistor element, the thermal stress can be buffered by the wire or the Au bump, so that the electric connection between the thermistor element and the lead terminal is achieved. A thermistor element capable of ensuring a stable connection.

Further, by connecting the thermistor body and the lead terminals using bumps, there is no need for soldering.
It will be environmentally friendly.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a thermistor element according to Embodiment 1 of the present invention.

FIG. 2 is a front view of the thermistor element shown in FIG. 1;

FIG. 3 is a top view of a lead terminal on which a bump is formed according to the first embodiment of the present invention.

FIG. 4 is a top view of the thermistor element before forming a coating layer according to the first embodiment of the present invention.

FIG. 5 is a side sectional view of a thermistor element according to Embodiment 2 of the present invention.

FIG. 6 is a top view of a lead terminal on which a solder layer is formed according to the second embodiment of the present invention.

FIG. 7 is a side sectional view of a conventional thermistor element.

8 is a front view of the thermistor element shown in FIG. 7 before coating.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Thermistor body 12a Lead terminal 12b Lead terminal 13 Wire 14 Coating layer 15 Bump 16 Solder layer 121 Support part

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masahiko Ajiyama 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F term (reference) 5E034 BA09 BA10 BB01 DA02 DB04 DB05 DC02 DC04

Claims (2)

[Claims] 1. An electric device comprising: a thermistor body having two planes; a metal wire on one surface of the thermistor body; and at least one bump made of Au or Ag on the other surface. A thermistor element comprising: at least two lead terminals which are electrically connected; a covering layer which covers the thermistor body, the metal wire, the bump, and a part of the lead terminal. 2. An electric device comprising: a thermistor body having two planes; a metal wire on one surface of the thermistor body; and a solder layer having a uniform thickness of 1 to 15 μm on the other surface. At least two lead terminals, which are electrically connected,
The thermistor body, the wire, the solder layer, and a coating layer covering a part of the lead terminal, wherein the solder layer is equal to or less than an adhesion surface between the thermistor body and the lead terminal. Thermistor element with a size of.