JP2002286558A - Temperature sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a size, heighten a resistance value, reduce electric power consumption, enhance sensititvity, measurement precision, easiness in manufacture, reliability, vibration proofness and the like, and reduce dispersion in temperature responses. SOLUTION: A temperature detecting element 22 formed with a metal foil resistor is attached to a tip part of a slim band-like flexible printed-wiring board 23 by bump joining to be stored in a protection tube 4, and the temperature detecting element 22 is pressed to an inner wall of the protection tube 4 by elasticity of the flexible printed-wiring board 23. Four external lead wires 7 are connected to the metal foil resistor via a terminal 47 and a circuit pattern 27 of tire flexible printed-wiring board 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature sensor, and more particularly, to a temperature sensor capable of reducing the size and increasing the resistance value and improving the measurement accuracy and the like.

[0002]

2. Description of the Related Art In the semiconductor market, in accordance with recent advances in microfabrication technology (micromachine technology), wafer diameters, pattern miniaturization, and cost reduction have been increasingly progressing. At present, mass production of a semiconductor IC having a pattern width of 0.13 μm on a large-diameter wafer of 300 mm is rapidly progressing. In this case, for example, a caliber of 300
When a pattern having a pattern width of 0.13 μm is formed on a wafer having a thermal expansion coefficient of 2.6 × 10 ⁻⁶ / ° C., for example, the temperature difference between the central portion and the peripheral portion of the wafer is 0.01 ° C. (10 ° C.).
m ° C), the pattern width is ± 0.0078μ
m (= 300 × 10 ^-3 × 2.6 × 10 ^-6 × 0.01) That is, if there is a temperature difference of ± 10 m ° C., the pattern width becomes 0.1
3 μm ± 6% (= 0.0078 / 013), which causes a decrease in yield. For this reason, in a semiconductor manufacturing apparatus, it is necessary to control the temperature with higher precision in order to increase the diameter of a wafer and to make a pattern finer. For example, if a temperature accuracy of ± 10 m ° C. is required, it is necessary to control the temperature one digit below (1/10), that is, ± 1 m ° C. unit. Therefore, the temperature controller is also 1
m ° C control is required, and the temperature sensor also has sensitivity and high reliability of 1m ° C, high-speed response (high-speed response speed),
Higher levels such as low power consumption are required. In current temperature control, a platinum resistor type temperature sensor excellent in stability and reliability is usually used as a temperature sensor.

FIG. 8 shows a conventional platinum resistor type temperature sensor used in a semiconductor manufacturing apparatus or the like. This platinum resistor type temperature sensor 1 is made of platinum (Pt) having a large resistance temperature coefficient.
Is used as the resistance wire 2, and the Pt resistance wire 2 is wound around an elongated glass tube 3 and housed in the protection tube 4. The Pt resistance wire 2 has an outer diameter of about 0.01 mm and a resistance value of 100Ω.
It is about. The glass tube 3 is made of glass, ceramic, or the like, and has a diameter of about 0.5 to 1 mm and a length of about 5 to 10 mm. The protection tube 4 is formed of SUS304, SUS316, or the like, and has an outer diameter of about 1.5 to 2 mm.

[0005] Reference numeral 5 denotes an insulating tube for insulating the Pt resistance wire 2 and the protection tube 4 from polyimide or the like, and has an outer diameter of about 1 to 1.5 mm and a length of about 10 mm. Reference numeral 6 denotes a relay connection line that connects the Pt resistance wire 2 and the external lead wire 7, and 8 denotes a metal pipe that holds the external lead wire 7. Reference numeral 9 denotes a filler (adhesive) made of epoxy resin or the like filled in the metal pipe 8, reference numeral 10 denotes a stainless steel knitting wire for protecting the external lead wire 7, reference numeral 11 denotes a connection end of the relay connection wire 6 and the external lead wire 7. Reference numeral 12 denotes a glass cloth insulating tube for preventing a short circuit, and reference numeral 13 denotes an insulating tube of polyimide or the like for preventing a short circuit of the connecting wire 6 for relay.

The connection between the protection tube 4 and the metal pipe 8 is performed by filling a filler material 9 to seal the protection tube 4 and simultaneously fix the relay connection wire 6 and the external lead wire 7. . The connecting wire 6 for relay has a diameter of 0.1 to
0.3 mm, about 15 mm in length made of Ag (silver) wire or the like, spot welded 14 to the Pt resistance wire 2,
The external lead wires 7 are connected by solder.

Since the inner diameter of the protection tube 4 is small, an external lead wire 7 having a normal thickness cannot be inserted into the protection tube 4 and directly connected to the Pt resistance wire 2. 2
A thin relay connection wire 6 is connected, and this connection wire 6 is drawn out of the protective tube 4 and connected to an external lead wire 7.

Although three external lead wires 7 are usually used, four external lead wires 7 are used for performing highly accurate measurement. When there are three lead wires (3-wire type), one lead wire is connected to one end of the Pt resistance wire 2 and two lead wires are connected to the other end. The measurement in this case is
First, the resistance value is measured with the lead wires at both ends of the Pt resistance wire 2, and then the resistance values of the two lead wires are measured. And
The resistance value of the Pt resistance wire 2 itself is obtained by subtracting the resistance values of the two lead wires from the initial resistance value. In this case, half of the remaining one lead wire and two lead wires
Are measured assuming that the resistance values of the Pt resistance wire 2 are the same, that is, the resistance values of all the lead wires are the same.
Since the resistance value is as low as 0Ω, an error occurs in the temperature measurement.

When there are four lead wires (four-wire system), two wires are used for the current wire, and the remaining two wires are used for the signal detection wire, and each is connected to each end of the Pt resistance wire 2, and the two current wires are used. Current is supplied by the lead wire for Pt, and Pt is supplied by two lead wires for signal detection.
The voltage of the resistance wire 2 is measured. That is, in the case of the four-wire system, a current flows from one lead wire and the voltage between both ends of the Pt resistance wire 2 is measured with the remaining lead wires, so that the resistance value of the Pt resistance wire 2 is not affected by the resistance value of the lead wire. There is an advantage that only the measurement can be performed with high accuracy.

However, in the case of the conventional platinum resistor type temperature sensor 1 shown in FIG. 8, since the relay connection line 6 is used, its resistance value is added to the resistance value of the Pt resistance line 2, and Since the temperature characteristic is added, an error occurs compared to the Pt resistance wire 2 itself.

[0010]

As described above, the conventional platinum resistor type temperature sensor 1 has the following problems because the resistance value is low in a wound type.

The resistance value of the Pt resistance wire 2 is usually 100Ω
Since the temperature is low, it is necessary to supply a large current when measuring a minute temperature change. However, in this case, since the thermal influence of the self-heating is inevitably increased, high-precision measurement cannot be performed.

For example, using a resistor having a resistance value of 100Ω
If the temperature changes by 1 ° C, the resistance value will be about 0.4Ω
And the current at that time is 1 mA, the signal voltage is
0.4 mV. Therefore, the power consumption at this time is
10^-FourW (W = RI^Two= 100 × 10 ^-3× 10^-3). It
Therefore, using such a temperature sensor 1 in a semiconductor manufacturing apparatus
Attempting to control the temperature by 1m ° C causes the sensor to generate heat.
The amount (power consumption) is large and control is disturbed. But
Thus, the pattern width of about 0.1 μm
Form a pattern of about m by photo-etching
In this case, the temperature of the temperature sensor
And control the temperature control.
Will not be able to.

However, since the above-mentioned conventional Pt resistor type temperature sensor 1 is a wound type, the diameter of the Pt resistor wire 2 is set to 0.01 mm (a thin wire which can be worked by humans).
Therefore, the resistance could not be increased. Because, to increase the resistance, a longer P
This is because it is necessary to wind the t resistance wire around the glass tube 3, so that the shape of the temperature detecting element is inevitably increased, and the response to a temperature change is sacrificed. In addition, the winding operation requires careful attention and is a difficult operation.

Temperature characteristics (resistance value) of the relay connection line 6
Is added to the temperature characteristics and the resistance value of the Pt temperature detecting element, causing variations in characteristics and a decrease in temperature accuracy.

Since the insulating tube 5 is used to insulate the Pt resistance wire 2 from the protection tube 4, the outer diameter of the protection tube 4 is further increased, and the sensitivity (response) to a temperature change is reduced. .

Since the protective pipe 4 and the metal pipe 8 are connected by the filler 9, they cannot be used in a liquid because they are susceptible to an external environment, particularly humidity. If the filler 9 peels or cracks at the connection between the relay connection wire 6 and the external lead wire 7 or at the connection between the protective tube 4 and the metal pipe 8 due to humidity or temperature change, the Pt resistance wire The resistance value of No. 2 drifts and a measurement error easily occurs.

Since the Pt resistance wire 2 and the relay connection wire 6 are connected by the spot welding 14, the spot welding work is difficult and the reliability of the connection is reduced. That is, when the Pt resistance wire 2 becomes extremely thin, the end of the Pt resistance wire 2 is likely to remain, but jumps out of the lath coat and insulation failure easily occurs. Further, as the Pt resistance wire 2 becomes thinner, the Pt resistance wire 2 in the welded portion is more easily broken. , Conduction failures and the like are likely to occur. There is no member for supporting the insulating tube 5, and it is uncertain which part of the Pt resistance wire 2 or the glass tube 3 will contact which part of the protective tube 4, and the transmission of heat from the protective tube 4 varies, Variations in temperature response hinder high-precision control.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems. It is an object of the present invention to achieve both miniaturization and high resistance simultaneously, to reduce power consumption and improve sensitivity. It is an object of the present invention to provide a temperature sensor capable of causing the temperature sensor to perform an operation. Another object of the present invention is to provide a temperature sensor capable of improving measurement accuracy. A further object of the present invention is to provide a temperature sensor capable of improving easiness of manufacture, reliability, vibration resistance and the like and reducing variation in temperature response.

[0019]

According to a first aspect of the present invention, there is provided a temperature detecting element having a temperature detecting metal foil resistor formed thereon, and the temperature detecting element is attached to a tip end. It comprises an elongated strip-shaped flexible printed wiring board, and an elongated protective tube accommodating the flexible printed wiring board and the temperature detecting element. In the first invention, the metal foil resistor can be formed by photoetching. In addition, the resistance value can be easily set, the temperature detecting element can be made smaller than the resistance wire, and a resistor having a high resistance value can be obtained.

According to a second aspect, in the first aspect,
In this example, two current lines and two signal detection lines are connected to the metal foil resistor of the temperature detection element. In the second invention, a four-wire temperature sensor is configured by passing a current through two current lines and measuring a voltage between both ends of the metal foil resistor with the remaining two signal detection lines. Therefore, the temperature can be measured with high accuracy without being affected by the resistance value of the external lead wire.

According to a third aspect, in the first or second aspect, the temperature detecting element is pressed against the inner wall surface of the protection tube by utilizing the elasticity of the flexible printed wiring board. In the third aspect of the present invention, since the temperature detecting element is pressed against the inner wall surface of the protection tube, the temperature transmission from the protection tube is good, the temperature response does not vary, and the temperature detection element moves due to vibration, impact, or the like. Without this, a stable resistance value can be maintained.

According to a fourth aspect of the present invention, the first, second or third aspect is provided.
In the invention, the metal foil resistor of the temperature detecting element and the circuit pattern of the flexible printed wiring board are bump-bonded. In the fourth aspect of the present invention, in the bump bonding, a solder piece such as a solder ball (bump) is placed on a pad portion of the resistor, and the metal foil resistor and the circuit pattern are overlapped so that the pad portions overlap each other. This is a joining method in which the solder pieces are melted and fused together. Therefore, a wide bonding area can be obtained, and since the position of the pad portion is accurately formed by photoetching, positioning can be easily performed as compared with the soldering operation, and highly reliable bonding can be obtained.

According to a fifth aspect of the present invention, the first, second or third aspect is provided.
In the invention, the metal foil resistor of the temperature detecting element and the circuit pattern of the flexible printed wiring board are connected by bonding wires, and the bonding portion is molded with a synthetic resin. In the fifth invention, the bonding strength of the wire bond is increased. Also, since only the bonding part is molded with synthetic resin,
When the temperature changes, the occurrence of distortion due to the difference in thermal expansion coefficient between the synthetic resin and the substrate or resistor can be reduced.
Therefore, drift of the resistance value does not occur, and highly accurate measurement can be performed.

According to a sixth aspect of the present invention, the first, second or third aspect is provided.
In the invention, the metal foil resistor of the temperature detecting element is covered with a flexible printed wiring board. Sixth
According to the invention, since the metal foil resistor is covered with the flexible printed wiring board, it does not come into contact with the protection tube and short-circuit.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. 1A and 1B are a cross-sectional view showing an embodiment of a temperature sensor according to the present invention and an enlarged cross-sectional view of an element unit, FIG. 2 is a plan view of a temperature detecting element, and FIG. FIG. Note that the same or equivalent components as those described in the section of the related art are denoted by the same reference numerals, and description thereof will be omitted as appropriate. In these figures, reference numeral
The temperature sensor indicated by 0 includes an element unit 21 and a metal pipe 8 in which the element unit 21 is incorporated.

The element unit 21 includes a temperature detecting element 2
2, a flexible printed wiring board 23 having the temperature detecting element 22 attached to the tip thereof,
2. The elongated protective tube 4 for accommodating the flexible printed wiring board 23, the external lead wire 7, and the external lead wire 7 and the flexible printed wiring board 23 are electrically connected and the protective tube 4 is hermetically sealed. And the like.

The temperature detecting element 22 comprises a ceramic substrate 24 made of alumina or the like, and a metal foil resistor 25 formed on the surface of the ceramic substrate 24. The ceramic substrate 24 is formed in a thin and elongated sheet shape having a width of about 0.8 mm, a length of about 5 mm, and a thickness of about 0.4 mm, and the metal foil resistor 25 has four pad portions 26 (26).
a-26d) and a well-known photo-etching technique.

The metal foil resistor 25 is formed in a meandering shape by bonding a material such as nickel or platinum having a large temperature coefficient of resistance to the surface of the ceramic substrate 24 and etching it in a predetermined pattern. Two portions 26 are formed in parallel. The metal foil resistor 25 is covered with an insulating film. The metal foil resistor 25 has a line width of about 10 μm and a resistance value of about 1,000.
0Ω. The pad section 26 is formed at one end of the ceramic substrate 4. In addition, these pattern shapes and numerical values do not limit the present invention.

The flexible printed wiring board 23 comprises
A main body 23A having an appropriate elasticity (spring property) formed of a thin and elongated band shape having substantially the same width as that of the ceramic substrate 24 by polyimide or the like, and a circular shape (integrally provided at the base end of the main body 23A). Or square connection 2
3B. Four circuit patterns 27 (27a to 27d) are formed in parallel on the surface of the main body 23A, and pad portions 28 (28a to 28d) are formed at the ends thereof in correspondence with the pad portions 26 of the metal foil resistor 25. Each is formed. That is, the circuit patterns 27a, 27
b correspond to the pad portions 26a and 26b of the metal foil resistor 25, and correspond to the circuit patterns 27c and 28b.
The pad portions 28c and 28d of the 27d are
Are formed to correspond to the pad portions 26c and 26d, respectively. Furthermore, a flexible printed wiring board 2
3, a cover 23C is formed integrally with the surface of the temperature detecting element 24 to cover a portion where the metal foil resistor 25 is formed. To prevent short circuit by contacting the inner wall surface.

Of the four circuit patterns 27, for example, two circuit patterns 27a and 27d on both sides are used as current lines for supplying a current to the metal foil resistance line 25,
The circuit patterns 27b and 27c are used as signal detection lines for detecting a voltage when the metal foil resistor 25 is energized. On the other hand, land portions 29 are formed on the base end side of each circuit pattern 27, respectively. These land portions 29
Are formed on the surface of the connection portion 23B, and insertion holes 30 through which the terminals 47 of the hermetic component 45 are inserted are formed in the center thereof. The circuit pattern 27, the pad portion 28, and the land portion 29 are simultaneously formed by a printed wiring board molding technique, and thereafter, only the circuit pattern 27 is covered with an insulating film.

Such a flexible printed wiring board 2
The circuit pattern 27 of No. 3 and the metal foil resistor 25 of the temperature detecting element 22 are bump-bonded. At the time of bonding, as shown in FIG. 4, solder pieces 31 such as solder balls are placed on the respective pad portions 26 of the metal foil resistor 25, and the flexible printed wiring board 23 is turned upside down.
8a to 28d are placed on the temperature detecting element 22 so as to correspond to the pad portions 26a to 26d, respectively, and a high-temperature heat sink 33 is pressed from above to melt the solder pieces 31,
The pad 26 and the pad 28 are fused. Pad part 2
Since 6, 28 are formed by photoetching, they can be accurately positioned. In addition, bump bonding has high reliability because it has a large bonding area, and can be automated. At the time of bump bonding, a pad portion 39 is also provided at the tip of the cover portion 23C of the flexible printed wiring board 23, and this pad portion 39 is connected to a pad portion provided separately from the metal foil resistor 25 by the solder piece 31. When the bump bonding is performed, the metal foil resistor 25 can be reliably covered without the cover portion 23C being turned up, and a short circuit of the metal foil resistor 25 with the protection tube 4 can be prevented. The same effect can be obtained by simply covering the resistor without the pad 39 and the pad of the metal foil resistor 25.

The external lead wires 7 consist of four wires (only two wires are shown in FIG. 1), two of which are for current wires and the other two are for signal detection wires. Connected to each other. The external lead wire 7 and the terminal 47 are connected by the solder 32, and the connection portion is sealed and reinforced by the synthetic resin 44.
The synthetic resin 44 is not always necessary.

The hermetic part 45 includes four terminals (lead wires) 47, a metal ring 48 such as Kovar formed in a cylindrical shape with both ends open, and this ring 48.
And a sealing glass 49 for sealing the terminal 47 therein. In such a hermetic component 45, a metal ring 48 is mounted on a sealing mold, and
The sealing glass 49 powder-formed by a press is inserted into the inside of the container, and the terminal 47 is further inserted into an insertion hole provided in the sealing glass 49, and the sealing glass 49 is heated and melted in a firing furnace, and the terminal 47 is It is manufactured by sealing the metal ring 48 together.

The terminal 47 is formed in a pin shape by Kovar or the like, penetrates a metal ring 48, and has a front end portion as shown in FIG.
As shown in FIG. 3, the circuit pattern 27 is connected to the land 29, and the rear end is connected to the external lead wire 7 as described above. Terminal 47 and land 29
Of the terminal 47 is connected to the small hole 30 of the land 29.
And connected by solder 35 (FIG. 5A).
And this connection part may be sealed with synthetic resin 35. Also, the terminal 4 is provided on the surface of the hermetic part 45.
7 is potted with a synthetic resin 43 to reinforce it.

Such a hermetic component 45 is directly press-fitted into the protection tube 4, but if the outer peripheral surface of the metal pipe 48 is plated with solder or gold, the protection tube 4 is sealed with higher airtightness. And sealing reliability can be improved.

FIGS. 6A and 6B show another embodiment of the hermetic component. FIG. 5A shows a hermetic component 5 including a terminal 47, a ceramic stem 51, and a metal film 52 metalized on the outer peripheral surface of the ceramic stem 51.
3 is shown. Such a hermetic part 5
3 is manufactured by temporarily firing a ceramic stem 51 having an insertion hole, and then inserting a terminal 47 into the insertion hole and performing a final firing. Further, as another manufacturing method, the terminal 47 is inserted into the insertion hole of the fired ceramic stem 51 and is filled with ceramic cement, or the terminal 47 coated with ceramic cement is inserted into the insertion hole, and the ceramic 47 is inserted. The cement may be fired.

The metal film 52 to be metallized on the outer peripheral surface of the ceramic stem 51 is formed by applying a metallizing liquid in which a metal powder such as molybdenum or tungsten is mixed into a solvent to the outer peripheral surface of the ceramic stem 51 and firing it. You. Since molybdenum and tungsten have a thermal expansion coefficient close to that of the ceramic stem 51, the surface of the ceramic stem 51 can be metallized without cracking.
Furthermore, if the metallized surface is plated with nickel, copper, gold or the like which is easy to be brazed, the protection tube 4 can be sealed with higher airtightness, and the reliability of the sealing can be improved. it can. That is, the metallization of the metal film 52 is performed to further enhance the reliability, but the sealing performance can be secured without the metal film 52.

FIG. 3B shows a terminal 47, a ceramic stem 51, a metal film 52 for metallizing the outer periphery thereof, and a metal film 5 for metallizing the peripheral surface of the terminal 47.
4 and 5 show an example in which the hermetic component 55 is configured. Such a hermetic component 55 is obtained by firing the ceramic stem 51 having the insertion hole, then metallizing the inner peripheral surface of the insertion hole with a metal film 54, and then inserting the terminal 47 into the insertion hole to form a solder, tin, or the like. It is manufactured by brazing with a brazing material such as lead. The metal film 52 provided on the outer periphery of the ceramic stem 51 is formed by the same method as described above. The metal film 54 is formed by applying a glass mixed with a metal powder such as molybdenum, tungsten, palladium, silver or the like to the inner peripheral surface of the insertion hole and firing it.
It is to be noted that the metal film 52 can secure the sealing performance even if it is not the same as described above.

The protection tube 4 is made of SUS304 or SUS3
A small-diameter small-diameter pipe 4A whose base end is opened and its distal end side is closed, and a large-diameter pipe 4B fitted to the base end of the small-diameter pipe 4A and joined by welding or the like. It is configured. Small diameter pipe 4A
Has an outer diameter of 1.2 mm, an inner diameter of 1.0 mm, and a length of 20
The temperature detecting element 22 and the flexible printed wiring board 23 are incorporated therein. The outer diameter of the large diameter pipe 4B is substantially equal to the inner diameter of the metal pipe 8. The small-diameter pipe 4A and the large-diameter pipe 4B are connected by brazing or welding. The rear end opening of the large diameter pipe 4B is hermetically closed by press-fitting the hermetic component 45, and an inert gas or oil is sealed inside. At the time of encapsulation, it is desirable to enclose under pressure. As the inert gas, argon, nitrogen, dry air or the like is used. As the oil, a silicone oil or the like is used. In this embodiment, the protection pipe 4 is composed of two members, a small diameter pipe 4A and a large diameter pipe 4B, which are connected by brazing or welding.
However, the present invention is not limited to this, and a protective tube integrally having a small-diameter portion corresponding to the small-diameter pipe 4A and a large-diameter portion corresponding to the large-diameter pipe 4B by drawing may be used. Of course.

The hermetic part 45 (or 53,5)
As a fixing method for the large-diameter pipe 4B of 5), besides press-fitting, there are projection welding and brazing.
Projection welding requires large welding equipment and electrical work, and brazing is not preferable because brazing equipment is required. In the case of press-fitting, only a small hand press is required as a facility, and the operation is simple. When measuring the temperature in an environment where the environment is not so severe, such as indoors or dry air, only press-fitting is sufficient.

The metal pipe 8 is a pipe having both ends opened and formed of SUS316 or the like.
0 mm, the inner diameter is about 3.0 mm, the length is about 30 to 50 mm, the large-diameter pipe 4B is inserted into the front end side, and the stainless steel knitted wire 10 that protects the external lead wire 7 is inserted into the rear end side, The inside of the metal pipe 8, that is, the hermetic component 45 is filled and sealed with a synthetic resin (thermosetting resin) 46.

In manufacturing such a temperature sensor 20, first, the flexible printed wiring board 23 and the temperature detecting element 22 are joined by bump joining. Next, the connecting portion 23B of the flexible printed wiring board 23 is bent as shown in FIG. 5A, and the terminals 47 are inserted through the insertion holes 30 (FIG. 3) of each land portion 29, and are connected by the solder 35.
Further, the connection portion may be molded and reinforced by a synthetic resin 36 (FIG. 1).

Next, the flexible printed wiring board 23 to which the temperature detecting element 22 is attached is inserted into the protection tube 4,
The hermetic part 45 is pressed into the large diameter pipe 4B. At this time, the front end and the back surface of the temperature detecting element 22 are connected to the small-diameter pipe 4.
Press against the inner wall of A. This pressing is performed by the elasticity of the flexible printed wiring board 23 itself and the connection portion 23.
This is performed using the return force due to the bending of B. As a method for further increasing the elasticity of the flexible printed wiring board 23, as shown in FIG.
It is preferable to provide a bent portion 58 having a character shape. Since the bent portion 58 has a force (restoring force) for returning to the original shape, the main body 23A can be extended, and the temperature detecting element 22 can be reliably pressed against the inner wall surface of the protective tube 4. In addition, before the large diameter pipe 4B is sealed by the hermetic part 45, an inert gas or oil is sealed inside the protective tube 4 to manufacture the element unit 21. It can be a unit.

Next, the element unit 21 is inserted into the metal pipe 8 to project the small-diameter pipe 4A to the outside.
Stainless steel wire 1 of external lead wire 7 connected to terminal 47
0 is fixed by filling the entire inside of the metal pipe 8 with the synthetic resin 46, and the fabrication of the temperature sensor 20 is completed.

According to the temperature sensor 20 having such a structure, since the metal foil resistor 25 is used, the temperature sensor 20 is compared with the conventional temperature sensor 1 of the winding type using the Pt resistance wire 2 shown in FIG. The resistor itself does not require strength (since it does not need to be wound around the glass tube 3) and has a large resistance value, for example, 1,
A resistor of about 000Ω can be formed, and the sensor can be easily manufactured and can be reduced in size. That is, in the conventional Pt temperature sensor 1, when the resistance value is increased as described above, the length of the Pt resistance wire 2 becomes longer,
The shape is inevitably large. Therefore, if the resistance value is 1,
A 000 Ω resistance wire could not be used.

On the other hand, in the case of the metal foil resistor 25, since a pattern can be formed by photoetching, a resistor having a desired resistance value can be freely manufactured. That is, if the pattern width is reduced, the resistance value can be increased (although there is a limit of photo etching, it is not the ratio of the winding type Pt resistance wire).
It is possible to manufacture a resistor having a resistance value of 1,000Ω on the minute ceramic substrate 24. Further, the manufacture of the metal foil resistor 25 is relatively easy as compared with the Pt resistance wire 2,
Since the temperature detecting element 22 itself can be formed in an elongated strip shape despite the high resistance value, the diameter of the small-diameter pipe 4A of the protective tube 4 that accommodates the temperature detecting element 22 can be reduced to 1.2 mm or less. Therefore, the temperature sensor 20 itself can be downsized. Furthermore, if the protective tube 4 can be formed thin, the heat capacity is also reduced, so that the response to a temperature change of the object to be measured can be improved.

Further, since the resistance value of the metal foil resistor 25 is high, compared with the conventional Pt temperature sensor 1, a small amount of heat is generated at a low current, and a minute change in temperature can be detected with high sensitivity and high accuracy. .

[Comparison of the conventional Pt temperature sensor with the temperature sensor of the present invention] The conventional Pt temperature sensor 1 has a resistance value of 10
A measurement current of 1 to 2 mA flows at 0 Ω, and a temperature change output is taken out. For example, when the current is 1 mA, the calorific value (power consumption RI ² ) of the resistor is 100 × 10 ⁻³ × 10 ⁻³ =
10 ⁻⁴ W = 0.1 mW. Assuming that the sensitivity is TCR (temperature coefficient) = 3850 ppm / ° C., the sensitivity at 1 ° C. is 100 × 3850 × 10 ⁻⁶ × 1 × 10 ⁻³ = 385 μV /
° C. The sensitivity at 1 m ° C. becomes 1/1000 of the sensitivity, which is 0.385 μV / ° C. That is, the conventional Pt temperature sensor 1 having a resistance value of 100Ω detects an output of a temperature change of 0.385 μV with power consumption of 0.1 mW.

On the other hand, when the metal foil resistor 25 having the same temperature coefficient of resistance of 1,000Ω is used, the resistance value becomes ten times, so that the same sensitivity (temperature change output) is obtained. Can reduce the measured current to 0.1 mA, that is, 1/10. 0.385 × 10 ⁻⁶ １０００ (1000 × 3850 × 10 ⁻⁶ ×
10 ⁻³ ) = 0.1 mA The calorific value (power consumption) of the metal foil resistor 25 is 1000 ×
10 ⁻⁴ × 10 ⁻⁴ = 10 ⁻⁵ W = 0.01 / mW, 1/1
It becomes 0. Therefore, increasing the resistance value can reduce power consumption while maintaining sensitivity, and is very effective when used in a semiconductor manufacturing apparatus requiring temperature control of 1 mC.

The four circuit patterns 27 formed on the flexible printed wiring board 23 and the hermetic parts 4
5 and the external lead wire 7 and the metal foil resistor 2
5 is connected, the temperature sensor 20 can be a four-wire type sensor despite the diameter of the protection tube 4 being reduced. Therefore, the voltage between both ends of the metal foil resistor 25 can be measured, and the external lead 7, the circuit pattern 27 and the terminal 4 can be measured.
7, the temperature can be measured with high accuracy without being affected by the resistance value.

The distal end surface and the lower surface of the temperature detecting element 22 are pressed against the inner wall surface of the small-diameter pipe 4A of the protective tube 4 by the elasticity of the flexible printed wiring board 23. Good temperature transmission, little variation in temperature response, and no movement due to vibration, impact, etc., so that a stable resistance value can be maintained and accurate temperature measurement can be performed. .

The metal foil resistor 25 and the circuit pattern 2
Since the bumps 7 are bump-bonded, the bonding operation is easier and more automatic than the bonding by ordinary soldering, and the reliability of the bonding can be improved.

Since the large-diameter pipe 4B of the protection tube 4 is hermetically sealed by the hermetic part 45,
It is possible to reliably prevent the intrusion of water, moisture, and the like, to maintain the electrical characteristics of the metal foil resistor 25 stably for a long period of time, and to obtain a temperature sensor excellent in reliability and environmental resistance. it can. Furthermore, since an inert gas or oil is sealed inside, responsiveness to a temperature change can be improved.

FIGS. 7A and 7B are a side view and a plan view showing another embodiment of the present invention. In this embodiment, the metal foil resistor 25 of the temperature detecting element 22 and the circuit pattern 27 of the flexible printed wiring board 23 are connected by bonding wires 60 instead of bump bonding, and the connection is sealed with a synthetic resin 61. Reinforced. In this case, as a method of sealing with the synthetic resin 61, it is desirable to seal the entire temperature detecting element 22 in order to enhance environmental characteristics. However, in this case, the sealing between the synthetic resin 61 and the ceramic substrate 24 or the metal foil resistor 25 is performed. Distortion occurs due to the difference in thermal expansion coefficient between the metal foil resistors 25
Is unfavorable because it causes the resistance value to drift. Therefore,
In the present embodiment, only the joining portion is made of synthetic resin 61.
To prevent the occurrence of distortion and to prevent the metal foil resistor 2
5 is prevented from drifting. The other structure is exactly the same as that of the above embodiment.

It is apparent that the same effect as that of the above-described embodiment can be obtained in such a structure.

[0056]

As described above, the temperature sensor according to the present invention can achieve both the miniaturization of the sensor itself and the increase in the resistance value at the same time. It is suitable for use in measurement. Further, the metal foil resistor can freely obtain a desired resistance value as compared with the resistance wire.

Further, since the present invention employs the four-wire system, the voltage between both ends of the metal foil resistor can be measured. Accordingly, the resistance value of the resistor can be set large without being affected by the resistance value of the external lead wire, so that a high-precision temperature measurement with little error can be performed, and the measurement accuracy of the sensor can be improved. .

In the present invention, since the metal foil resistor and the flexible printed wiring board are joined by bump joining or bonding wires, the joining is easy and the reliability can be improved.

Also, in the present invention, the temperature detecting element is pressed against the inner wall surface of the protective tube by utilizing the elasticity of the flexible printed wiring board, so that the temperature response is less scattered and the temperature detecting element is not affected by vibration, impact, etc. And a stable resistance value can be maintained.

Further, according to the present invention, since the metal foil resistor is covered with the flexible printed wiring board, the metal foil resistor does not contact the protection tube to short-circuit.

[Brief description of the drawings]

1A and 1B are a cross-sectional view showing an embodiment of a temperature sensor according to the present invention and an enlarged cross-sectional view of an element unit.

FIG. 2 is a plan view of a temperature detecting element.

FIG. 3 is a plan view of a flexible printed wiring board.

FIG. 4 is a view showing a state of bump bonding.

FIGS. 5A and 5B are diagrams showing a connection between a flexible printed wiring board and external lead wires, and a diagram showing an example in which the flexible printed wiring board is bent to give elasticity.

FIGS. 6A and 6B are half sectional views showing other embodiments of the hermetic component.

FIGS. 7A and 7B are a side view and a plan view showing another embodiment in which a metal foil resistor and a circuit pattern are connected by bonding wires.

FIG. 8 is a sectional view showing a conventional Pt resistor type temperature sensor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Pt resistance temperature sensor, 2 ... Pt resistance wire, 3 ... Glass tube, 4 ... Protection tube, 5 ... Insulation tube, 6 ... Relay connection wire, 7 ... External lead wire, 8 ... Metal pipe, 20 ... Temperature Sensor, 21: Element unit, 22: Temperature detecting element, 23
... flexible printed wiring board, 24 ... ceramic substrate, 25 ... metal foil resistor, 27 ... circuit pattern, 37 ...
Terminal, 45: Hermetic component, 47: Terminal, 60: Bonding wire, 61: Synthetic resin.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Matsuo Zama 238 Itaizawa, Nakatadai, Ouchi-cho, Yuri-gun, Akita 1-in-1 Alpha Electronics Co., Ltd. (72) Inventor Toru Okamoto Ouchi-cho, Yuri-gun, Akita 238 No. 1 Itazawa Nakata-shiro Alpha Electronics Co., Ltd. F-term (reference) 2F056 CE08

Claims (6)

[Claims] 1. A temperature detecting element on which a metal foil resistor for temperature detection is formed, and an elongated strip-shaped flexible printed wiring board having the temperature detecting element attached to a tip portion thereof. A temperature sensor comprising: an elongated protective tube that houses the temperature detecting element. 2. The temperature sensor according to claim 1, wherein two current lines and two signal detection lines are connected to the metal foil resistor, respectively. 3. The temperature sensor according to claim 1, wherein the temperature detecting element is pressed against the inner wall surface of the protective tube by utilizing the elasticity of the flexible printed circuit board. 4. The temperature sensor according to claim 1, wherein the metal foil resistor of the temperature detecting element and the circuit pattern of the flexible printed wiring board are bump-bonded. 5. The temperature sensor according to claim 1, wherein the metal foil resistor of the temperature detecting element and the circuit pattern of the flexible printed wiring board are connected by a bonding wire, and the bonding portion is molded with a synthetic resin. A temperature sensor, characterized in that: 6. The temperature sensor according to claim 1, wherein the metal foil resistor of the temperature detecting element is covered by a flexible printed wiring board.