JPH0344977A - Thermally sensitive sensor - Google Patents

Abstract

PURPOSE:To improve the heat responsiveness and environmental resistance of the title sensor by providing a thin-thickness section in the substrate of the sensor and forming a thermally sensitive thin-film body on the surface of the section in such a way that the thin-film body is not brought into contact with a body to be detected. CONSTITUTION:The main body section 1 of this thermally sensitive sensor is provided with a thin-thickness section A in its substrate 11 and thermally sensitive thin-film bodies 3 are formed on the surface of the section A so that the bodies 3 can be faced to a mounted substrate 2. The section A is also formed as an insulating base material layer where the thin-film bodies 3 are formed and the electric connection between the substrate 2 and main body 1 is made through wireless bonding by using a bump 6. Then enclosing sections 8 are formed between the main body section 1 and substrate 2 so as to enclose the wireless bonding section and the section where the bodies 3 are formed and make the bodies 3 to face the enclosed space S from the outside. Since the bodies 3 do not come in direct contact with a body to be detected, the bodies 3 can be improved in heat responsiveness and environmental resistance, because they can detect the temperature of a liquid also.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a temperature sensor for sensing the temperature of gas or liquid.

[Conventional technology]

Various types of temperature sensors have been used to detect and measure the temperature of gases such as air and liquids (subjects) such as water, among which resistance type temperature sensors and thermocouple type temperature sensors , thermopile type temperature sensors, etc. are widely used because they can extract temperature signals in the form of electrical signals and are easy to use. These normally have a structure in which a bulk temperature sensitive body (for example, a gold MII wire) is housed in a protective tube or metal sheath. Some resistance-type temperature sensors use a thermistor made of a cylindrical or disk-shaped sintered semiconductor powder body as a temperature sensor.

However, since conventional temperature-sensitive sensors are relatively large, the sensor itself has a large heat capacity and does not have sufficient responsiveness.

Temperature sensors whose temperature sensing part does not come into direct contact with the subject are
Thermal response is particularly inadequate. Temperature sensors in which a thin metal wire comes into direct contact with the object have relatively good thermal response, but the thin metal wire that serves as the temperature sensor is prone to breakage and characteristic deterioration, making them unreliable. .

[Problem to be solved by the invention]

Therefore, a temperature-sensitive sensor as shown in FIG. 3 has been proposed to improve the thermal response.

This temperature sensor has a sensor main body 31 on a mounting board 32, in which a base 41 has a thin part A' and a temperature sensitive thin film 33 is formed on the surface of the thin part A' having the same thickness. It has the following structure.

In this case, a portion of the insulating film 41a becomes a thin portion A'. The sensor body 31 is fixed to the bottom of the recess 42 of the mounting board 32 with an adhesive 43. The temperature-sensitive thin film body 33 is, of course, made of a thin film, and examples thereof include a temperature-sensitive resistor, a thin-film thermocouple, and a thermopile structure.

The signal from the temperature sensitive thin film body 33 is sent to the mounting board 32.

Therefore, an electrical connection is required between the sensor main body 31 and the mounting board 32. In the case of this temperature-sensitive sensor, the sensor body 31 and the mounting board are connected by a thin metal wire 44 (wire bonding) between the lead-out terminal part 33a of the sensor main body 1 and the connection terminal part 34 on the surface of the mounting board 32. 32
I am trying to make an electrical connection between them.

In this temperature sensor, since the temperature-sensitive thin film body 33 is used, the sensor body 31 itself is miniaturized, and moreover, the temperature-sensing section is essentially made up of the thin portion A' of the sensor body 31 and the temperature-sensitive thin film body 33. The overall thickness of the temperature-sensing section is extremely thin and the heat capacity is extremely small, so that the thermal response is significantly improved.

However, this temperature sensor does not have sufficient reliability.

This is because the area around the thin metal wire 44 bonding in the sensor main body 31 is directly exposed to the subject and is easily damaged. It would be possible to cover the bonded portion of the thin metal wire 44 with a protective film, but since the sensor body 31 is extremely small as described above, it is not easy to form a protective film that selectively covers the bonding portion.

In view of these circumstances, this invention has excellent thermal responsiveness,
Moreover, it is an object of the present invention to provide a temperature-sensitive sensor that has excellent environmental resistance and is highly reliable.

[Means to solve the problem]

In order to solve the above-mentioned problems, the temperature-sensitive sensor of the present invention has a sensor main body having a thin part on the base and a temperature-sensitive thin film formed on the surface of the thin part with the same thickness, and a sensor main body having a thin part on the mounting board. The surface on which the temperature-sensitive thin film body is formed is arranged so as to face the mounting board, and the electrical connection between the mounting board and the main body of the sensor section is made by wireless bonding, and the wireless bonding part and the temperature-sensing body are electrically connected to each other by wireless bonding. A sealing material is applied between the sensor main body and the mounting board so as to seal the bottom of the thin film body from the outside.

The sensor body is extremely miniaturized to improve thermal responsiveness. Since the configuration uses a temperature-sensitive thin film body to sense temperature rather than a bulk temperature-sensitive body, ultra-miniaturization is possible.

The mounting board functions to hold such an ultra-small sensor main body and to perform electrical input/output to the sensor main body. This mounting board connects signals from the sensor body to electronic circuits outside the sensor. In addition to a configuration that only has a function, a configuration that also includes an electronic circuit for processing signals from the sensor main body is used. The mounting board itself is usually made of synthetic resin such as epoxy resin or ceramics such as aluminum.

Examples of the temperature-sensitive thin film body include, but are not limited to, a thin-film type temperature-sensitive resistor, a thin-film type thermocouple, and a thin-film type thermopile structure. The thin portion is made of an insulating film such as a silicon oxide film or a silicon nitride film, and a temperature-sensitive thin film body is formed thereon.

Wireless bonding is performed by a so-called bump method, a direct bonding method, or the like.

Since the temperature-sensitive thin film body does not come into direct contact with the subject, the temperature-sensitive sensor of the present invention can sense the temperature not only of gases such as air but also of liquids such as water. Further, the temperature sensor of the present invention can be used as a temperature sensor in a humidity sensor or a wind speed sensor that measures humidity and wind speed by sensing gas temperature.

[For production]

The temperature sensor according to the present invention has very good thermal responsiveness. This uses a temperature-sensitive thin film body 3, which allows the sensor main body 1 to be made ultra-small, and as shown in FIG.
This is because the temperature-sensing part is separated by the thin part A of 1 and the temperature-sensitive thin film body 3, and the thickness of the temperature-sensing part as a whole is extremely thin, and the heat capacity of the temperature-sensing part is extremely small. The sensor main body is fixed to the mounting board 2 upside down, which is the opposite of the conventional method, so that the subject comes into contact with the back side of the surface on which the thermosensitive thin film 3 is formed, but the temperature sensing operation by the thermosensitive thin film 3 There are no problems. This is because, as seen above, the thickness of the temperature-sensing section is extremely thin, so even if the surface in contact with the subject is reversed, there is no substantial change in the amount of heat left behind.

Moreover, this temperature sensor has excellent environmental resistance and high reliability. This is because the temperature sensitive thin film body 3 portion and the wireless bonding portion are sealed from the outside and are hardly affected by the environment. Although the sensor main body l is placed on the mounting board in an upside-down state opposite to the conventional one, the electrical connection between the mounting board and the sensor main body can be easily and reliably established by wireless bonding.

〔Example〕

Next, one embodiment of the temperature sensor according to the present invention will be described.

FIG. 1 shows the main structure of an embodiment of the temperature-sensitive sensor of the present invention.

The temperature sensor has a structure in which a sensor body 1 is mounted on a mounting board 2. The sensor body 1 is fixed in a recess 21 with a step 22 provided on the mounting board 2 - side.

The sensor body 1 has a thin part A on its base 11, and a temperature-sensitive thin film 3 is formed on the surface of the thin part A with the same thickness, and the surface on which the temperature-sensitive thin film 3 is formed faces the mounting board 2. It is arranged as follows.

The base 11 of the sensor body 1 has an insulating film 11b laminated on one side of the silicon plate 11a, and a recess 11 formed from the other side of the silicon plate 11a so that the insulating film 11b remains at the bottom.
c is provided. The diaphragm-shaped insulating film portion at the bottom of the recess 11C is the thin portion A. Therefore, the thin portion A also serves as an insulating base material layer as it is, and the temperature-sensitive thin film body 3 is formed here.

On the other hand, the electrical connection between the mounting board 2 and the sensor body 1 is made by wireless bonding using so-called bumps 6. A sealing part 8 made of a sealing material is provided between the sensor main body part 1 and the mounting board 2 so as to seal the wireless bonding part and the part where the temperature-sensitive thin film body 3 is formed from the outside. 3 faces the sealed space S.

Note that, as in the other embodiment shown in FIG.
In addition, a bancivation (Sins) film 25 is laminated on the extraction terminal portion (excluding the bump-shaped bottom region) 3a, and the sealing material is fed to the tip of the wireless bonding portion, and the wireless It may also be configured such that a bonding portion is embedded.

Note that the temperature sensor of the present invention is not limited to the above-mentioned configuration. For example, the sensor body and the mounting board may be wirelessly bonded outside the recess of the mounting board. Furthermore, a flat mounting board with no recesses is used, the sensor body is mounted so as to be lifted by the thickness of the bump, and a sealing part is provided around the sensor body. There may be.

The sensor main body may also be of a type in which another temperature-sensitive thin film body is formed in the thick part, and rapid temperature changes can be sensed from the signal difference between the respective temperature-sensitive thin film bodies. In this case, the heat sink is also assembled to the mounting board. For example, the mounting board has a hole through which the assembled heat sink is brought into contact with the sensor body.

Next, a manufacturing example of the above-mentioned temperature sensor will be explained.

First, the base body 11 is produced. Using a silicon plate 11a having a (100) plane on its surface, an insulating film 11b made of silicon nitride with a thickness of about 5,000 yen is formed on the negative side, and then the insulating film 11b is etched from the other side of the silicon plate 11b by anisotropic etching. It is a 11c shape groove that reaches the bottom of the hole. In this way, a base 11 having a two-layer portion (thick portion) of the silicon plate 11a and the insulating film 11b and a single-layer portion (thin thickness portion) consisting of the diaphragm-shaped insulating film 11b is obtained.

Next, a thin platinum film having a thickness of about 2,000 layers is deposited on the entire surface of the insulating film 11b of the obtained substrate 11 using, for example, a sputtering method, and patterned using a photolithography method to form a thermosensitive thin film. 3 and a lead-out terminal part 3a are formed, and a gold bump 6 for electrical connection to the lead-out terminal part 3a is formed using photolithography to form the sensor main body part 1. In the case of the embodiment shown in FIG. 2, it goes without saying that the pansivation film 25 is also laminated.

On the other hand, as the mounting board 2, as shown in FIG.
A gold pattern for wiring having a concave portion 21 and a connecting terminal portion 4 on the surface of the step 22 is separately prepared. In this case, the depth of the step 22 is made approximately equal to the thickness of the base 11.

In this way, the base 11 and the mounting board 2 become flush with each other with the sensor main body 1 placed in the recess 21.

Next, the surface of the sensor body 1 on which the temperature-sensitive thin film 3 is formed is placed in the recess 21 so as to face the surface of the mounting board 2, and the bump 6 is bonded to the connection terminal 4 by thermocompression bonding.

In the manufacturing example described above, the bumps 6 were formed on the drawer terminal portion 3a, but the bumps 6 may be formed on the connection terminal portion 4.

Finally, as shown in FIG. 1 or 2, the gap between the side surface of the sensor body 1 and the side surface of the recess 21 of the mounting board 2 is filled with a sealing material such as resin to form a sealing part 8. , the temperature sensor is completed.

〔Effect of the invention〕

As described above, the temperature sensor of the present invention has excellent thermal responsiveness because the heat capacity of the temperature sensing part is very small. Since the hot part does not deteriorate or the electrical connections are damaged, it has sufficient environmental resistance and is highly reliable.

[Brief explanation of drawings]

FIGS. 1 and 2 are schematic cross-sectional views showing the main structure of a temperature-sensitive sensor according to the present invention, and FIG.
FIG. 2 is a schematic cross-sectional view showing the main part configuration of a conventional temperature sensor.

Claims (1)

[Claims] A sensor body having a thin part on one base and a temperature-sensitive thin film formed on the surface of the thin part of the same thickness is mounted on a mounting board so that the surface on which the temperature-sensitive thin film is formed faces the mounting board. electrical connection between the mounting board and the sensor main body is made by wireless bonding, and the sensor main body is arranged so as to seal the wireless bonding part and the temperature-sensitive thin film forming part from the outside. A temperature sensor that is sealed with a sealing material between the part and the mounting board.