JPS5979821A - Detection of maximum temperature - Google Patents

Abstract

PURPOSE:To enable a handy measurement of temperature from a low to the maximum level without contamination of vacuum atmosphere or the like by forming a vacuum evaporated film of a metal such as Au and Ni on an insulating substrate at a temperature lower than the temperature to be measured to be used particularly for measuring the temperature of parts in or inside of a vacuum container. CONSTITUTION:A single metal 3 such as Au, Pt, Ni, Fe, Pd, Cu and Ag is evaporated, for example, on an insulating substrate or a conductor 1 with an insulated surface at the thickness of 50-500Angstrom at the substrate temperature lower than the temperature to be measured in order to measure the inside of an electron tube or the like and parts in and walls of a vacuum vessel unable to use a thermocouple or the like. For example, an Ag paste is sintered on a substrate 1 to form an electrode 2 and an Au film 3 evaporated at 50 deg.C. The electric resistance of the film 3 remains unchanged upto the substrate temperature of 50 deg.C, increases as the crystallinity gains with the rise in the temperature beyond 50 deg.C and becomes constant at the temperature (270 deg.C or so for Au) at the temperature of maximizing the crystallinity. The ratio is predetermined between the minimum resistance value R0 (at the maximum temperature) and the differences of the resistance DELTAR at temperature T during the rise in the temperature from the resistance R0 and from the resistance R50 at 50 deg.C and then, the ratio between the results and the DELTAR/R50 is obtained to enable the detection of the temperature upto the maximum level continuously.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to a method for detecting the maximum temperature of a component or wall of a vacuum vessel.

Conventionally, thermocouples and the like could not be used; for example, to measure the temperature of the inner wall of glass pulp in an electron tube, the highest temperature was detected by a temperature detection element that utilized the melting point of a pure metal or alloy, and by detecting a change in the shape or color of the element. . However, with this detection method, if the vacuum level of the electron tube is reduced,
They had major drawbacks, such as the temperature values that could be detected were discontinuous and unreliable, and there were few that could be put to practical use.

SUMMARY OF THE INVENTION An object of the present invention is to provide a simple method for continuously detecting the maximum value of a temperature to be measured without contaminating an atmosphere such as a vacuum.

The method of detecting the maximum temperature of the present invention is Au, Pt.

A method that utilizes the fact that the electrical resistance of a vacuum-deposited film of a single metal element (D) such as Ni, Fe, Pd, Cu, or Ag irreversibly changes to a value corresponding to the highest temperature experienced by the annealing effect. Then, the desired substrate (including the part to be tested) [a vacuum-deposited film formed by a normal vacuum deposition method is placed under the temperature to be measured, and then a predetermined temperature lower than that temperature (e.g. room temperature) In this method, the electrical resistance is measured and the maximum temperature is determined from, for example, an electrical resistance-maximum temperature curve that can be calibrated in advance.Here, the substrate is glass.

Any insulating substrate such as ceramic or quartz, or a conductive substrate with an insulated surface may be used.The thickness of the vacuum-deposited film is preferably 50 to 500 A for ease of resistance measurement, but there are limitations on both. isn't it. Further, when forming this metal vacuum-deposited film, it is desirable to suppress or select the substrate temperature to a value lower than the temperature to be measured, and the evaporation rate and film thickness to constant values, respectively, depending on the measurement accuracy.

According to the present invention, since the interior of a vacuum-deposited metal film formed on a relatively low-temperature substrate has crystal defects such as lattice misalignment, when exposed to a temperature to be measured higher than the substrate temperature, Elimination of defects in the crystal is promoted, and the electrical resistance value changes to a low value corresponding to the maximum temperature to be measured, so that the desired maximum temperature can be easily obtained. Also, unlike conventional detection methods, the entire atmosphere to be measured is not contaminated.

Next, the present invention will be described in detail with reference to the drawings, focusing on examples of Au vacuum-deposited films. FIG. 1 shows an example of a temperature detection element for implementing the method of the present invention when measuring the maximum temperature of a substrate to be evaporated during dielectric deposition in a vacuum evaporation apparatus. In this figure, the temperature detection element is placed on a glass substrate 1 of 20 mfrI x 20 mm, which is the same as the substrate to be evaporated.
A g-paste baking pole 2 was provided, and an Au vapor-deposited film 3 having an effective surface of 5 mm x 14 mm was formed through a black leather mask under the conditions shown in Table 1.

Table 1 Vapor deposition conditions of Examples Solid lines 4 and 5 in FIG.
(”O) and the electrical resistance of the detection element at 25°C R/
An example of the relationship with 几0? , the horizontal axis shows the temperature T(''O) and the vertical axis shows the electrical resistance ratio R,/RO.Here, R is the maximum temperature TC'O)?25℃ of the sensing element experienced. The electrical resistance value in air is 0, which indicates the minimum electrical resistance value.The measurement of electrical resistance was carried out in air at 25°C, so it is the result of repeated experiments. The electrical resistance V 0 does not change until the deposition substrate temperature T reaches 50°C, and the temperature of the substrate 1 of the temperature detection element was 50°C when the Au vacuum-deposited film 3 was formed. It can be seen that the electrical resistance decreases depending on the temperature, and the minimum value ratio is 0 at about 270°C.

Therefore, by measuring the electrical resistance ratio RZR0 of the Au vacuum-deposited film 3, the highest temperature experienced by the dielectric deposition substrate can be determined. On the other hand, the desired maximum temperature can also be obtained by detecting the ratio of the change in resistance ΔR to the electrical resistance ratio R/l (, where the initial electrical resistance of the vacuum-deposited Au film at room temperature is expressed as o). Referring to Figure 3, the horizontal axis is the maximum temperature T ("0), and the vertical axis is the initial electrical resistance R1+
Electrical resistance change when experiencing maximum temperature T'r for 6
An example of the calibration curve for sample wind 5 in Table 1 above is shown as the percentage of R ΔR/RIIO (%), and the electrical resistance ratio ΔR
It can be seen that the maximum temperature T can also be obtained by detecting /R,,'i.

In these examples, the electrical resistance ratio of the Au vacuum-deposited film 3 when left at room temperature and normal pressure, the change over time of 0 is as well known (a large change is observed immediately after Au vapor deposition, but the film Thickness: 50-500A, deposition rate: 2QA/sec
Below, for 100 days after the first day of vapor deposition, at most 2%
Only slight changes were observed, and they were very small. However, since the sensitivity to the maximum temperature varies depending on the Au deposition rate and film thickness, the change over time becomes somewhat large, but high sensitivity can be achieved by increasing the deposition rate and reducing the total film thickness. Furthermore, as can be seen from this example, the temperature range in which IC measurement is possible is such that the lower limit is the substrate temperature when forming the Au vacuum-deposited film 3 of the detection element, and the upper limit is the temperature at which the electrical resistance ratio is Ro, which is the lowest, that is, the electrical resistance It is determined by the recrystallization temperature of the Au vacuum-deposited film from the viewpoint of characteristics. Table 2 shows the inventor's research results regarding this measurable temperature range for other Examples other than Au. Although alloy films of these metal elements were investigated, they could not be put to practical use as temperature sensing elements due to problems such as alloy promotion and segregation.

Table 2 This example was effective as an overheat detection element for a low-temperature vacuum processing furnace and a temperature element for glass pulp in an electron tube. Although the description has been given with limitations on the shape and basics of the element, it is clear that these explanations are mere examples and do not limit the intended purpose of the invention of the present application or the scope of the claims. .

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the detection element used in the detection method of the present invention, and FIG. 2 shows the relationship between the maximum temperature to be measured and the electrical resistance ratio of the detection element in FIG. 1. As an example, FIG. 3 is a graph showing the maximum temperature to be measured in the detection element of FIG. 1 and the rate of change in electrical resistance of the detection element. 1...Base, 2...Electrode, 3...
...Au vacuum-deposited film, 4,5.5'...detection characteristics of the example, l(, /l(@...electric resistance ratio,
T(”O)...Maximum temperature, △R/Rh....Electric resistance change rate. 1st concave 2nd day -3, -2 on 3rd day

Claims (1)

[Claims] ALII, Pt, Ni, F'e formed on a substrate
, Pd, Cu. A vacuum-deposited film made of any one of metal elements such as Ag is placed under a temperature to be measured, and the maximum temperature of the temperature to be measured is determined by detecting an irreversible change in the electrical resistance of the vacuum-deposited film. How to detect.