JP7340130B1 - Non-contact temperature sensor - Google Patents

Abstract

[Problem] In a conventional non-contact temperature sensor, the electrode surface of the thermistor is arranged so as to face the conductive paste (solder or metal particle paste) applied to the conductor surface of the insulating substrate. However, due to the difference in thermal expansion and surface tension due to the difference in the amount of paste applied, the expansion of the enclosed bubbles, and the gas generated, a phenomenon occurs where the paste rises above the insulating base, and convection is generated from the gap, which absorbs the incident energy. Sensing accuracy and speed decrease, and metal particle paste causes non-ohmic contact, leaving concerns about measured values. [Solution] To prevent the thermistor from lifting up from the insulating base, use a weight, rod, elastic body, etc. for the thermistor, apply continuous pressure to the conductive material through the thermistor, and create a composition resistance between the upper surface of the insulating base and the heat-sensitive function of the thermistor. It is a non-contact temperature sensor that adjusts the gap between the body layers, improves the ohmic connection with the metal particle paste, and efficiently and accurately captures the energy from the heat source with other solders and metal particle pastes, increasing measurement accuracy. [Selection diagram] Figure 1

Description

The present invention relates to the spacing between a thermistor (FIG. 2) having a composition resistor layer with a heat-sensitive function on an insulator and an insulating substrate having a pair of conductor parts on which the thermistor is mounted, and It relates to ohmic contact of metal particle paste, which is a type of conductive material interposed between insulating substrates.

A non-contact temperature sensor is made possible by electrically connecting the electrode part of a thermistor having a composition resistor layer with a heat-sensitive function on an insulating material and a pair of conductor parts provided on an insulating substrate.

Non-contact temperature sensors detect the temperature of radiation energy (infrared rays including far infrared rays, ultraviolet rays, etc.) emitted by the object to be measured without contact, and then detect the temperature through units such as electrically connected lead wires. temperature display and temperature control.

Products using the non-contact temperature sensor include copy machines, printers, microwave ovens, thermometers, wind speed sensors, and the like.

Comparing the major features with conventional contact type temperature sensors, we find that conventional types come in contact with the fusing heat roller of copiers, printers, etc., which causes some scratches on the roller and causes streaks on printed matter. In the case of a non-contact type temperature sensor, since it is not in contact with the roller, it does not cause scratches, and in the microwave oven, the temperature of the food can be observed in a targeted manner, which is convenient for thawing, etc.

International publication number W02016/152222

In the non-contact temperature sensor shown in Figure 1, radiation energy (7, infrared rays including far-infrared, ultraviolet rays) emitted from an object (8, heat generation source) is transmitted to the lower surface of an insulating substrate on the object side. The composition resistor layer (4) of the thermistor moves from 5a) to the upper surface of the insulating substrate (5b) by heat conduction, and measures the temperature of the upper surface of the insulating substrate (5b).

In Patent Document 1, a composition resistor layer having a heat-sensitive function is provided on an insulator, and a thermistor having a pair of electrodes is disposed on an insulating base, but the gap between the thermistor and the insulating base becomes large or The slope of the thermistor body may become large, making measurement of incident energy unstable, leading to low precision and inaccurate control of temperature, and resulting in low yield.

The schematic diagrams in FIGS. 3 and 7 show the main conditions that cause a decrease in yield.

The mechanism of the decrease in yield is that the thermistor (2), which has a composition resistor layer with a heat-sensitive function and a pair of electrodes electrically connected on an insulator, is a surface-mounted component, and its shape and weight are As an example, in a shape of 1.0 (length) x 0.5 (width) x 0.3 (thickness) [mm] (hereinafter referred to as 1005), if alumina is used as the insulator, the bulk density is 3.5 g. / ^cm3 , it is 0.525 mg from volume x bulk density, and if it has a shape of 1.6 mm in length, 0.8 mm in width, and 0.3 mm in thickness (hereinafter described as 1608), it is 1.344 mg, Because it is light, it is easily affected by vibrations generated during assembly, wind during the heating process, and distortion caused by thermal expansion of assembly jigs and tools. ends up forming a slope.

In addition, the conductive material used as the raw material has a large effect, and the thermistor easily lifts up or forms a slope due to differences in thermal expansion and surface tension due to differences in the amount of coating, as well as bubbles contained within and gases generated during the heating process. (Fig. 3) (Fig. 7).

These are composition resistors with a heat-sensitive function, in which a supporting material (temporary bonding material) that improves contact with an insulating substrate (5) equipped with a pair of conductor parts (6) at the time of installation is in contact with the upper surface (5b) of the insulating substrate. A major reason is that layer (4) cannot be used because it contaminates the surface.

There are two types of conductive materials: one is a solder paste, and the second is an organic type of metal particles (gold, silver, platinum, etc.), such as a metal particle paste with a filler of epoxy resin, or an inorganic type. There are metal particle pastes (silver paste, gold paste, etc.) that are made by mixing materials such as glass as fillers.

When solder paste is used for electrical connections, it solidifies in a conical shape due to surface tension, etc., forming a gradient that causes a decrease in mechanical strength and convection phenomena (10), which increases resistance value fluctuation (ripple). In addition, in the case of metal particle paste, the orientation of the metal particles contained inside is disordered (Figure 7), resulting in non-ohmic contact where the metal particles do not touch each other (Figure 5), resulting in resistance fluctuation (ripple). is also large, and the reliability of measurement accuracy is also poor.

The "state in which the orientation of metal particles is disordered" described here refers to the state in which the metal particle paste, which is a type of conductive material softened by heating, is not pressed or the state in which the contact with the insulating substrate is improved ( In the absence of the aid described in 0012), a gradient is formed and the directions of the metal particles are uneven, leading to non-ohmic contact in which the metal particles do not come into contact with each other.

Explaining the mechanism by which ohmic contact is created using other surface mount resistance components, one electrode has electrodes in five locations: top and bottom, left and right sides, and the surface that brings out the characteristics. The auxiliary agent (for example, rosin, flux) contained in the material acts to increase the wettability of the five surfaces, and the auxiliary agent that improves the contact with the insulating substrate described in paragraph (0012) is also present. This produces the same effect as pressing, and provides ohmic contact with good orientation that prevents parts from lifting.

However, the thermistor shown in Figure 2 has only one electrode on the bottom surface, and the other four surfaces (left, right, top, short and height sides) are made of insulators (ceramics, resin, etc.). Even if there is a supporting material in the conductive material, it will not get wet and will be repelled, and will further improve the contact with the insulating substrate. Both cannot be avoided.

This is because the surface tension of the conductive material (7, solder paste, metal particle paste) and the thermal expansion force of the enclosed bubbles are greater than the weight of the thermistor (2). In the case of metal particle paste, because there is no auxiliary agent to improve the contact, a gradient is formed due to uplift without being able to obtain ohmic contact, and this becomes smaller as the thermistor becomes smaller, for example, from 1608, 1005, In 03015, which has a length of 0.3, a width of 0.15, and a thickness of 0.3 [mm], the electrode part (3) area is even smaller, so that acceleration is achieved.

When the thermistor is installed with a gradient as shown in Figure 3, the gas that becomes lighter during measurement rises, creating a convection phenomenon (10), causing heat to escape, until the resistance value is saturated. The arrival time increases, and metal particle paste results in a non-ohmic connection, which causes problems with the IV characteristics in the low current (10 μA or less) region shown in Figure 5, and causes instability in other current regions due to changes in ambient temperature, etc. It becomes the resistance value.

In view of these problems, the present invention provides that the metal particle paste, a type of conductive material (7), forms ohmic contact, and that the conductive materials of both the solder paste and the metal particle paste suppress the formation of gradients. A technical disclosure will be made of a gap between an insulating substrate (5) and a composition resistor layer (4) with a heat-sensitive function of a thermistor (2), which is not affected by convection (10).

In the invention described in claim 1, the non-contact temperature sensor includes an insulating base (5) having a pair of conductor parts (6), and a pair of electrode parts electrically connectable to the pair of conductor parts (6). (3) and a thermistor (2) having a composition resistor layer (4) with a heat-sensitive function, electrically connecting the pair of conductor parts (6) and the pair of electrode parts (3). In order to do this, a conductive material (7) is interposed between the conductive material (7) and continuous pressure is applied to the insulating substrate upper surface (5b) and the composition resistor layer (4). This is a non-contact type temperature sensor characterized in that the distance between the two is preferably 2.0 mm or less.

The invention according to claim 2 is the non-contact temperature sensor according to claim 1, wherein the distance between the upper surface of the insulating substrate (5b) and the composition resistor layer (4) is most preferably 0.7 mm or less. be.

The invention described in claim 3 is a non-contact type temperature sensor in which the slope of the thermistor described in claims 1 to 2 is formed to be 3/10 or less.

The invention described in claim 4 includes an insulating base (5) having a pair of conductor parts (6), and a pair of electrode parts (3) disposed to face the pair of conductor parts (6). A thermistor (2) having a composition resistor layer (4) having a heat-sensitive function is interposed to electrically connect the pair of conductor parts (6) and the pair of electrode parts (3). In a non-contact temperature sensor comprising a conductive material (7), the distance between the upper surface of the insulating base (5b) and the composition resistor layer (4) is preferably 2.0 mm or less. , is a non-contact temperature sensor characterized in that the metal particle paste (7a) of the conductive material (7) has ohmic contact.

The conductive material (7) that electrically connects the electrode part (3) of the thermistor and the conductor part (6) of the insulating base is a solder paste or a metal particle paste containing metal particles of gold, silver, copper, platinum, etc. In both cases, emphasis is placed on ohmic contact, and one example of silver paste is H9403 series manufactured by Namics Co., Ltd.

FIG. 8 is a schematic diagram of an example in which the metal particle paste has ohmic contact, and the metal particle paste of the conductive material (7) is passed through the thermistor (2) from the time the thermistor is placed until the end of heating (hardening). Then, by applying continuous pressure, the direction of the metal particles is aligned in one direction, and the contacts change from point contact to line contact to surface contact, resulting in ohmic contact as shown in FIG. 6, and furthermore, no gradient is formed after placement.

If solder paste is used as the conductive material in the state shown in FIG. 8, the structure will be such that the gradient after placement is suppressed and the convection (10) phenomenon is also suppressed.

Observation of the effects of the invention is not stipulated by JIS standards, etc., so here we will observe the presence or absence of ohmic contact due to IV characteristics and the amplitude of the no-load resistance value fluctuation (ripple phenomenon) at the measured temperature. However, the most preferred temperature fluctuation width is less than ±1°C, the preferred fluctuation width is ±1°C≦swing width≦±2°C, and it is unsuitable for use if it exceeds ±2°C, and is non-ohmic. If contact was observed, it was judged to be inappropriate regardless of the preferred or most preferred vibration width.

In addition, to determine the placement of the thermistor, measure the difference in height between CD and C-E shown in Figure 9 after heating (after curing) using a laser displacement meter, observe the difference, and record the difference as a slope. did.

Figure 4 is a schematic diagram of an example of a method for measuring resistance fluctuation width at 85°C.The presence or absence of ohmic contact can be determined by observing the IV characteristics in Figure 5 using a curved laser or oscilloscope. In the case of ohmic contact, it was determined as non-ohmic contact in the case of a curve.

From Table 2, the sample numbers that satisfy both the conditions of temperature fluctuation of ±2°C or less and good ohmic contact are from Example sample number 1 in Table 2-1 to Example sample number 25 in Table 2-5. , Regarding the slope, it can be observed that the slope of 0 is from Example sample number 1 to Example sample number 20, and the allowed slope is up to 3/10 of Example sample number 25. From these results, The range of the gap is such that the lower limit is when the upper surface of the insulating substrate (5b) and the composition resistor layer (4) of the thermistor (2) are in contact (Table 2-1), and the upper limit is when the upper surface of the insulating substrate (5b) is in contact with the composition resistor layer (4) of the thermistor (2). It was observed that the diameter was 2.0 mm or less (Table 2-5).

Furthermore, from Table 2-1, the most preferable gap is that the lower limit value is a state in which the upper surface of the insulating substrate (5b) and the composition resistor layer of the thermistor are in contact, and the upper limit value from Table 2-3 is the condition where the upper surface of the insulating substrate (5b) is in contact with the composition resistor layer of the thermistor. ) and the composition resistor layer of the thermistor were observed to have a gap of 0.7 mm or less.

In the embodiment used for the effects of the invention, continuous pressure is applied from the weight (22) to the conductive material (7) via the thermistor (2) using a jig to induce ohmic contact, and then the fluctuation range of the resistance value is The placement of the thermistor was observed.

The composition of the thermistor (2) can be determined by measuring the slope from the height difference between the three corners of the thermistor shown in Fig. 9 after heating (curing), and by using a spacer (23) during the arrangement. By adjusting the gap between the resistor layer (4) and the top surface of the insulating substrate (5b), it is possible to understand the relationship between the convection (10) phenomenon and the temperature fluctuation width, and the permissible gradient can be found from Tables 2-1 to 2-5. From Table 2-5, Example Sample No. 25, it was observed that the lower limit value was 0 slope and the upper limit value was up to 3/10.

As for the arrangement situation in the example, in Tables 2-1 to 2-4, the slope of the thermistor cannot be observed and no convection occurs, but when the gap becomes large (2.5 mm or more) in Table 2-6, heat is generated. The escape phenomenon was observed in terms of temperature fluctuation (ripple phenomenon).

An example of a non-contact temperature sensor structure An example diagram of a thermistor equipped with a composition resistor layer An example of a structural diagram of a patent document An example of a schematic diagram of measurement conditions Example of VI curve (difference between ohmic and non-ohmic contact) An example of a schematic diagram of orientation in metal particle paste with ohmic contact An example of a schematic diagram of orientation in metal particle paste with non-ohmic contact An example of a schematic diagram of a state diagram with pressure applied An example of a schematic diagram of the slope measurement method An example of applying pressure without using weights or spacers

For example, a thermistor (2) having a composition resistor layer with a heat-sensitive function that is electrically connected to a pair of electrodes on an insulator can be made by using Pt, Au, etc., which will become a pair of electrodes on an insulator. sputter at least one type of metal, dry-etch, and anneal, sputter and laminate the composition resistor at least once leaving a part of the pair of electrode parts, lift off the metal, etc., and coat a predetermined portion with SiO ₂ Then, it is diced into 1608, 2125 shape, or 1005 shape with 2.0 (length) mm, 1.25 (width) mm, and 0.3 mm thickness depending on the case.

In a method other than sputtering, a pair of electrode parts are formed by vapor deposition, then lift-off and sintering are performed, and then a composition resistor layer is printed using a metal mask, leaving only a part of the electrode parts, and then leveled. There is also a method of ringing, annealing, leaving a part of the electrode part (3), covering it with glass, and dicing.

When covering areas other than the electrodes with glass, depending on the conditions, the glass may erode the composition resistor layer due to heating, causing movement of heavy metals such as Co and Ni within the composition resistor layer, resulting in fluctuations in resistance value. Cheap. This is particularly likely to occur if Fe, which is a sintering inhibitor, is included.

The effects of the invention were observed as shown in the schematic diagram of an example shown in FIG. An oil tank controlled at 85°C with a platinum resistance thermometer is used, and the area other than the hole (12) where a non-contact temperature sensor is installed is sealed, and radiation energy generated from the oil surface is sensed to detect fluctuations in resistance. Observe the width (resistance value fluctuations are significantly affected by convection, radiation, conduction, etc.).

In addition, in order to block electromagnetic waves and infrared rays from the surrounding area, the darkroom and the tools used were coated with matte black as much as possible to reduce the influence of external factors.

As a raw material to be prepared, a thermistor (2) having a composition resistor layer (4) with a heat-sensitive function and a pair of electrode parts (3) electrically connected on an insulating material, in the example, a 1608 shape. In addition, as an example, an insulating board (5) equipped with a pair of conductor parts, preferably a board with high infrared transmittance and absorption such as a polyimide board and which can be connected to the outside, solder paste or other A conductive paste (7), for example a silver paste, is required.

If the absorption rate of infrared rays of the insulating substrate is high, the time it takes to reach the infrared rays is short, but the heat dissipation is poor; if the transmittance is high, the composition of the thermistor's heat-sensitive function can directly warm the resistor layer, and the heat dissipation is poor. It depends on the density and structure of the insulation board, etc.

The auxiliary materials used to produce the example shown in Figure 1 are as follows: the weight (22) to be placed on the thermistor, its holder (21), and the gap between it and the insulating base. In the present invention, for the spacer (23) made of an insulating plate piece and the plate (19) that can withstand heating temperature, materials with high thermal diffusivity and small thermal expansion are selected, such as single crystal alumina, SiC, etc.

To explain with reference to FIG. 8, first, the insulating base (5) is fixed to the pin (20) of the plate (19), and then the insulating plate (5) serving as a spacer is placed between the pair of conductor parts (6) on the insulating base. 23) For example, temporarily attach hard glass, then apply silver paste (7) to the conductor part (6) on the insulating board (this order may be reversed), and make sure that it comes into contact with the silver paste (7). Place the electrode parts (3) of a pair of thermistors so as to face each other, press lightly toward the insulating base, then place the holder (21) and weight (22) and apply continuous pressure to the conductive material (7). Furthermore, since the holder (21) serves as a cover, it also has a windproof effect.

At this time, the silver paste (7) was applied so that the thickness of the spacer (23) used or the upper surface of the insulating substrate (5b) was 0.2 mm or more and 0.4 mm or less, and the conductor part of the insulating substrate ( 6) and a volume that can hide the thermistor electrode part (3) is required.

The spacer (23) adjusts the gap between the composition resistor layer of the thermistor and the upper surface of the insulating substrate (5b), and the weight also adjusts the gap between the composition resistor layer of the thermistor and the upper surface of the insulating substrate (5b), and the weight is used to adjust the gap between the thermistor and the upper surface of the insulating substrate. The purpose is to prevent and maintain continuous pressure.

FIG. 8 is a schematic diagram showing the weights (22) corresponding to the thermistor (2) solid, and the weight is preferably 1.0 g/mm ² or more.

FIG. 10 shows two examples of schematic diagrams of a method for controlling the pressure and the gap without using the weight (22) or the spacer (23).

The left side of FIG. 10 does not use a spacer (23), and instead of a weight (22), a height adjustment rod (25 ) For example, by adjusting the top and bottom of the rod, the gap between the composition resistor layer (4) of the thermistor (2) and the top surface of the insulating base (5b) can be adjusted and fixed, and continuous pressure is applied to the conductive material. Similarly, the figure on the right does not use a spacer (23), the depth of the plate body (26, including the elastic body) is adjusted by forming, and the upper surface of the insulation board ( By adjusting and fixing the gap between 5b) and the composition resistor layer (4), it is an auxiliary material jig that applies continuous pressure to the conductive material to lead to ohmic contact and electrical connection.

Next, the silver paste (7) is softened and hardened by heating, the thermistor electrode part (3) and the conductor part (6) of the insulating base are electrically connected, and after cooling, the holder (21) and the spacer (23) (insulated (object plate).

In the embodiment, if the insulating plate (23) is not temporarily attached, a slit, dimple, bump, etc. is formed on the electrode part of the thermistor, the conductor part side of the insulating base, or both in order to absorb excess conductive material. It is preferable to apply a buffer.

"A" in FIG. 1 is the thickness of the spacer used in the example.

The non-contact temperature sensor (1) prepared in the example was attached to the hole (11) 3 mm away from the top surface (16) of the oil tank set at 85°C as shown in Figure 4, and the outside air was directly A cover (11) is provided to prevent the thermistor resistance from being hit, and the fluctuation width (ripple) of the output resistance value is measured.However, the measured value is not the oil tank temperature of 85℃, but the fluctuation for one minute from the time when the thermistor resistance value is saturated. The width (ripple) is described.

In order to improve measurement accuracy, the non-contact temperature sensor was wrapped in an oil bath at a temperature of 65° C. to 90° C. and then immersed in the oil tank to measure each resistance value, and then the measurement was carried out.

The material of the insulator comprising the composition resistor layer having a heat-sensitive function is, for example, a crystalline material such as alumina or steatite, and an amorphous material such as hard glass such as Pyrex (registered trademark) glass, e-glass, s-glass, or organic material. Examples include tetrafluoroethylene, PP, etc., and alumina was used in the examples.

The composition resistor layer with a heat-sensitive function is an NTC thermistor of a composite oxide containing at least two selected from cobalt, manganese, nickel, copper, lanthanum, and iron, or barium titanate containing a trace amount of a rare earth element. There is a PTC thermistor.

The composition resistor layer used in the examples was an NTC thermistor with a volume resistivity of 1.5 kΩ·cm and a B constant of 4200 K _{(25° C./85° C.)} .

The insulating base is made of polyimide or PET for the flexible type, and paper phenol or glass epoxy for the rigid type.The conductor part is made of a base material mainly made of metal such as copper, such as copper foil or copper wire.

The "gradient" mentioned in the present invention refers to the difference in height of the three corners of the thermistor for each solid body after the thermistor is placed, contacts a conductive material, and is electrically connected through heating (hardening). It was measured between CD and CE shown in , and the value was converted into a form called X/10 slope, and in Table 2, X = "converted value".

The "arrangement" mentioned in the present invention refers to the range from when the electrode part of the thermistor contacts the conductive material until the end of heating (hardening), and the "arrangement situation" refers to the slope of the thermistor. .

1 Non-contact temperature sensor 2 Thermistor with a resistor layer 3 Electrode part of the thermistor 4 Composition resistor layer 5 Insulating base 5a Lower surface of the insulating base 5b Upper surface of the insulating base 6 Conductor part of the insulating base 7 Conductive material (solder paste, metal particle paste)
7a Metal particles in the conductive material 7b Organic matter in the metal particle paste 8 Target object (heat source)
9 Radiant energy (infrared rays, etc.)
10 Heat escape (convection, radiation)
11 Sealing cover (lid body)
12 Measuring hole 13 Lead wire 14 Oil tank housing 15 Oil tank 16 Oil tank top surface 17 After expansion of air bubbles contained in the conductive material 18 Measuring device (DMM, etc.)
19 Plate 20 Positioning pin between insulation board and plate 21 Holder 22 Weight (corresponds to each thermistor solid)
23 Spacer (insulator that maintains the gap)
24 Laser displacement meter 25 Rod (press adjustment screw for each thermistor solid, etc.)
26 Tap 27 Plate body (corresponds to each thermistor solid)

Claims (2)

The non-contact temperature sensor consists of an insulating base having a pair of conductor parts, and a thermistor having a composition resistor layer with a heat-sensitive function and having a pair of electrode parts that can be electrically connected to the pair of conductor parts. , in order to electrically connect the pair of conductor parts and the pair of electrode parts, a conductive material is interposed between the pair and the electrode parts, and a conductive material is interposed therebetween, and continuous pressure is applied to the conductive material to connect the upper surface of the insulating substrate and the composition. A non-contact temperature sensor characterized in that the thermistor has a gap of 2 mm or less with respect to the resistor layer, and the slope of the thermistor is 3/10 or less. A product comprising the non-contact temperature sensor according to claim 1 .