JPH01229924A - Temperature probe - Google Patents

Abstract

PURPOSE:To make connection work efficient by also completing the connection with electrodes simultaneously with the formation of a thermistor film, by forming the thermistor film to the electrodes exposed to the end part of an insulating substrate between the terminal parts thereof. CONSTITUTION:A thermistor material is bonded to the electrodes 5, 6 exposed to the end part of an insulating substrate 1 between the terminal parts thereof by a sputtering method to form a thermistor film 10. At this time, the connection of the thermistor film with the electrodes 5, 6 is also completed simultaneously with the formation of said thermistor film 10 and working efficiency can be improved markedly. Since the thermistor film 10 is bonded not only to the electrodes 5, 6 but also to the substrate 1, sufficient bonding strength can be secured against vibration or a shock. Further, since the outer surface of the thermistor film is covered with a protective film 11 and the electrodes 5, 6 are embedded in the substrate 1, there is no possibility such that moisture or harmful gas penetrates in this probe, and the thermistor film and the electrodes can be perfectly protected even under the severe environment for a temp. measuring part.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a temperature probe having a thermistor at its tip.

[Prior art and its problems]

Conventionally, this type of temperature probe includes one in which a conductor is wired inside a probe body, a thermistor is fixed to the tip of the probe body, and the electrode of the thermistor is connected to the conductor.

However, in the above configuration, the connection part between the thermistor and the conductor is close to the temperature measurement part, so it is easily affected by the harsh environment of the temperature measurement part, and simple connection methods such as soldering cannot be used, and wire bonding Connection methods such as brazing and brazing are limited. Therefore, there were problems in that the manufacturing process was inefficient and the bonding strength of the connection portion was insufficient. Furthermore, since the outside of the thermistor or conductor cannot be completely protected, the thermistor may deteriorate or the conductor may corrode due to the influence of moisture or harmful gases in the temperature measuring section, making it difficult to obtain a temperature probe with excellent durability. I couldn't.

[Purpose of the invention]

The present invention has been made in view of the above problems, and its purpose is to provide a temperature probe that is less susceptible to the influence of the measurement environment, has excellent durability, and is easy to manufacture.

[Structure of the invention]

The temperature probe of the present invention has at least two layers of electrodes that are not electrically conductive embedded in an insulating substrate, a thermistor film is formed between the ends of the electrodes exposed on one end surface of the substrate, and an outer surface of the thermistor film is provided. The above object is achieved by applying a protective film made of an insulating material to the substrate.

[Effect]

That is, since the thermistor film was formed by attaching the thermistor material between the ends of the electrodes exposed at the ends of the insulating substrate by the spacing method, the connection with the electrodes was completed at the same time as the thermistor was formed. This eliminates troublesome connection work such as wire bonding and brazing, and greatly improves work efficiency. Furthermore, since the thermistor film adheres not only to the electrodes but also to the substrate, sufficient bonding strength can be ensured against vibrations and shocks. Furthermore, since the outside surface of the thermistor is covered with a protective film and the electrodes are buried inside the substrate, there is no risk of moisture or harmful gases entering the inside, and the thermistor and electrodes can be used even in the harsh environment of the temperature measurement part. Fully protected.

(Example) Fig. 1 and Fig. 2 show an example of a temperature probe according to the present invention, in which a rod-shaped substrate 1 made of an insulating material such as ceramic
2 formed inside this substrate l that are not electrically conductive to each other.
The electrodes 5 and 6 of the layer, the electrode pads 8 and 9 formed on the upper and lower surfaces of the proximal end of the substrate 1, and the electrodes 5 and 6 formed adheringly between the ends of the electrodes 5 and 6 exposed on the distal end surface of the substrate l. Thermistor film lO
and a protective film 11 made of an insulating material and deposited to cover the outer surface of the thermistor film IO.

As shown in FIG. 3, the substrate 1 is formed by stacking three ceramic substrates 2, 3.4 before firing and firing them simultaneously. The above-mentioned band-shaped electrodes 5.6 are formed on the upper and lower surfaces of the central ceramic substrate 3, and one end of these electrodes 5.6 extends to the tip surface of the ceramic substrate 3, and the other end is made of ceramic. It terminates before the base end surface of the substrate 3. In addition, through holes 2a and 4a are formed in the base end portions of the upper and lower ceramics 14 by 2°4, and these through holes 2a and 4a are used to stack three ceramic substrates 2 and 3.4. When combined, the above electrode 5.6
Corresponds to the proximal end of. After firing the above substrate l,
By applying conductive plating to the base end of the through hole 2a+4
A through hole 7 is formed on the inner surface of a, and electrode bands 8.9 are formed on the upper and lower surfaces of the proximal end. Thereby, the electrode pads 8 and 9 and the electrode 5.6 are electrically connected via the through hole 7. The above electrode bands 8, 9
An external conductor (not shown) is connected to the terminal by soldering or the like.

When the substrate 1 is fired as described above, the electrodes 5 and 6 are exposed on the tip surface of the substrate 1.
A thermistor material made of a transition metal oxide such as i, Co, etc. is deposited by a spuck method or the like to form the thermistor film 10.
form. Thereby, the thermistor film IO is integrally fixed to the substrate 1 and electrically connected to the electrode 5.6. The initial resistance value of the thermistor film 10 is determined by the thickness of the central ceramic substrate 3 and the width of the electrode 5.6.
By changing these thicknesses and widths, the initial resistance value can be easily changed.

Note that the thermal shrinkage rate of the electrode 5.6 is that of the ceramic substrate 2.3.
If it is larger than 4, the electrodes 5 and 6 may not be exposed to the tip surface of the substrate 1 when the substrate 1 is fired, and it may not be possible to connect the thermistor material to the electrodes 5 and 6 even if the thermistor material is sputtered. It is only necessary to polish the tip end surface of the substrate 1 to a mirror surface. By polishing the tip end surface of the substrate 1, the electrodes 5 and 6 can be exposed reliably, and the adhesion to the substrate 1 can be prevented when the thermistor material is sputtered. The properties are also improved.

After forming the thermistor film 10 on the tip surface of the groups 4Fi, I, Aj! is formed so as to cover the thermistor film 10. A protective film 11 made of an insulating material such as ZCH, Si-N4, etc. is formed.

This allows the thermistor lI! 10 is completely isolated from the outside, and the thermistor film 10 can be used even under the harsh environment of the temperature measurement part.
tInjury and deterioration can be prevented.

In the above embodiment, a method for manufacturing one temperature probe has been described, but in reality, a large number of temperature probes are manufactured simultaneously as follows. That is, three wide ceramic substrates are prepared, and a large number of electrodes are formed on both upper and lower surfaces of the central ceramic substrate.

After stacking the three ceramic substrates and firing them, the substrates are cut one by one to form through holes and electrode bands on the upper and lower surfaces of the base of each substrate. Next, as shown in FIG. 4, a plurality of substrates 1 are placed one on top of the other with spacers 12 in between, with the end surfaces of the spacers 12 being slightly deeper than the end surfaces of the substrates 1, and the substrates 1 and spacers 12 After wax or the like 13 is injected into the formed recess and hardened, the end surface of the substrate 1 is polished to a mirror finish. Then, after attaching the thermistor material 4 to the end face of this substrate 1 by a spanner method or the like, only the wax 13 on the end face is removed with a lubricant or the like.
A protective film is formed by depositing an insulating material on the thermistor film. By manufacturing according to the procedure described above, temperature probes can be mass-produced.

In the above embodiment, the insulating substrate was formed by stacking three ceramic substrates, but other insulating materials such as resin may be used, and the method of forming the electrodes is not limited to the above embodiment. Furthermore, the present invention is not limited to the one in which through holes and electrode pads are formed at the base end of the insulating substrate in order to connect the electrodes and external conductive wires.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, since the thermistor film is formed between the ends of the electrodes exposed at the ends of the insulating substrate, the connection with the electrodes is completed at the same time as the thermistor film is formed, and the connection is completed. Work can be made much more efficient than before, and sufficient joint strength can be ensured.

In addition, the outer surface of the thermistor film is covered with a protective film and the electrodes are buried inside the substrate, so there is no risk of the thermistor or electrodes being eroded by moisture or harmful gases, even in the harsh environment of the temperature measurement part. A highly durable and stable temperature probe can be provided.

In addition, the thermistor film and protection 31! Since the film can be formed thin, the heat capacity can be sufficiently reduced, and a temperature probe with good thermal responsiveness can be obtained.

Note that by making the board a certain length and connecting the external conductor to the end opposite to the thermistor film side of the electrode, this connection can be placed in a stable environment away from the temperature measurement part. Therefore, a simple connection method such as soldering can be used, and there are no restrictions on connection methods.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an example of a temperature probe according to the present invention;
2 is a cross-sectional view taken along the line ■--■ in FIG. 1, FIG. 3 is an exploded perspective view of the substrate before firing, and FIG. 4 is a cross-sectional view when a large number of temperature probes are manufactured. l...Substrate, 2.3.4...Ceramic substrate, 5
゜6...electrode, 7...through hole, 8,9...
Electrode/<7 de, 10... thermistor film, 11...
Protective film.

Claims (1)

[Claims] At least two layers of electrodes that are not electrically conductive to each other are buried inside an insulating substrate, a thermistor film is formed between the ends of the electrodes exposed on one end surface of the substrate, and a protective film made of an insulating material is provided on the outer surface of the thermistor film. A temperature probe characterized by being coated with.