JP2016046429A - Wiring board, temperature sensing element, and temperature sensing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring board etc. which achieves excellent temperature detection accuracy.SOLUTION: A wiring board 5 includes: an insulating base 1; electrodes 2 provided on a main surface of the insulating substance 1; internal resistance wiring 3 provided in the insulating base 1; and via conductors 4 connecting the internal resistance wiring 3 with the electrodes 2. The internal resistance wiring 3 does not contain glass and the via conductors 4 contain glass.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wiring board, a temperature measuring body, and a temperature measuring device in which an internal resistance wiring is provided inside an insulating base made of a ceramic sintered body.

  A wiring board that uses a resistance wiring on the surface of an insulating base as a sensor for temperature detection in a high-temperature fluid (eg, several hundred to 1,000 ° C.) such as exhaust gas, and uses the change in the electrical resistance of the resistance wiring due to temperature It has been known. As the metal material, a material containing platinum (Pt) or the like as a resistance wiring is used from the viewpoint of oxidation resistance at a high temperature.

JP-A-8-201131

  However, in the above wiring board or the like, the resistance wiring contains glass in order to increase the bonding strength with the insulating base, and there are cases where the glass contains a part containing a lot of glass or a part containing a little glass, and the electric resistance is low. As a result, the temperature has been partially changed, and the temperature detection accuracy is lowered.

  A wiring board according to one aspect of the present invention includes an insulating base, an electrode provided on a main surface of the insulating base, an internal resistance wiring provided inside the insulating base, the internal resistance wiring, and the electrode. And the internal resistance wiring does not contain glass, and the via conductor contains glass.

  A temperature sensing element according to another aspect of the present invention includes the wiring board having the above-described configuration and a lead terminal connected to the electrode.

  A temperature measuring device according to another aspect of the present invention includes the temperature measuring element having the above-described configuration and a covering provided on the outer surface of the insulating base so as to cover the electrode.

  A wiring board according to one aspect of the present invention includes an insulating base, an electrode provided on a main surface of the insulating base, an internal resistance wiring provided inside the insulating base, and a via connecting the internal resistance wiring and the electrode. Since the internal resistance wiring does not contain glass and the via conductor contains glass, the internal resistance wiring has a uniform electrical resistance, and the via conductor has a cross-sectional area. Is relatively large and the electric resistance is unlikely to change partially, so that the temperature detection accuracy can be increased.

  Since the temperature sensing element according to another aspect of the present invention has the wiring board configured as described above, the temperature detection accuracy can be improved.

According to the temperature measuring device according to another aspect of the present invention, since the temperature measuring body having the above-described configuration and the covering provided on the outer surface of the insulating base so as to cover the electrodes, Among them, since the portion where the internal resistance wiring is provided is not covered with the covering, external heat is transmitted to the internal resistance wiring without being obstructed by the covering, so that the temperature detection accuracy is further enhanced.

It is a disassembled perspective view which shows the wiring board of embodiment of this invention. It is a partial longitudinal cross-sectional view of the wiring board of embodiment of this invention. (A) is a perspective perspective view which shows the temperature measuring device of embodiment of this invention, (b) is a top view of (a).

  A wiring board, a temperature measuring body, and a temperature measuring device according to an embodiment of the present invention will be described with reference to the accompanying drawings. The distinction between the upper and lower sides in the following description is for convenience, and does not limit the upper and lower sides when a wiring board or the like is actually used.

  FIG. 1 is an exploded perspective view showing a wiring board and a temperature sensor according to the first embodiment of the present invention. As shown in FIG. 1, an insulating substrate 1 is formed by laminating a plurality of insulating layers 1a (two layers in the example of FIG. 1). An insulating substrate 1 is provided with an electrode 2, an internal resistance wiring 3 and a via conductor 4 to form a wiring substrate 5. Further, the lead terminal 7 is provided on the wiring board 5 to form the temperature measuring body 6. In FIG. 1, the electrode 2, the internal resistance wiring 3 and the via conductor 4 which are disassembled for each of the two insulating layers 1a forming the wiring substrate 5 and are provided on each insulating layer 1a are shown. . Temperature measurement is performed using the fact that the resistance value of the internal resistance wiring 3 changes according to the temperature. That is, the temperature of the environment where the wiring board 5 and the like are located is calculated from the measured value of the resistance value of the internal resistance wiring 3 and detected.

  The insulating base 1 has a flat plate shape such as a square plate, and is a base portion for providing the electrode 2, the internal resistance wiring 3, and the via conductor 4. The insulating substrate 1 is formed of a ceramic sintered body such as an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body, or a glass ceramic sintered body. The insulating base 1 is formed by laminating a plurality of insulating layers 1a made of such a ceramic sintered body.

  For example, if each insulating layer 1a is made of an aluminum oxide sintered body, the insulating base 1 can be manufactured by the following method. First, a slurry prepared by adding and mixing an appropriate organic binder and solvent to raw powders such as aluminum oxide, silicon oxide, magnesium oxide, and calcium oxide is formed into a sheet by a doctor blade method or the like to form a ceramic green sheet. Make it. Next, after cutting these ceramic green sheets into appropriate dimensions, a plurality of these are laminated to produce a laminate. Then, the insulating substrate 1 is manufactured by firing the laminated body at a high temperature (about 1600 ° C.). Each of the plurality of ceramic green sheets becomes the insulating layer 1a. The insulating base 1 may contain glass.

  The internal resistance wiring 3 is provided inside the insulating substrate 1. The internal resistance wiring 3 is formed of platinum, which is a metal material whose electric resistance (resistance value) changes according to temperature, or a metal material containing platinum as a main component. In detecting the change of the resistance value of the metal material according to the temperature, it is preferable that the absolute value (initial value) of the electrical resistance of the metal material at the initial stage (for example, about 0 ° C. which is a reference temperature) is larger.

This is due to the following reason. That is, the change of the resistance value according to the temperature change of the internal resistance wiring 3 occurs at a constant ratio regardless of the initial resistance value magnitude (absolute value). That is, as the initial resistance value increases, the absolute value of the change in resistance value accompanying a temperature change increases. The greater the absolute value of the change in resistance value, the less susceptible to noise (resistance value fluctuations due to factors other than temperature changes). Measurement is also easier. Therefore, the internal resistance wiring 3 preferably has a large initial resistance value. Therefore, a metal material such as platinum has a linear pattern (that is, a pattern advantageous in increasing the absolute value of the resistance value because the length of the section in which the resistance value is measured is long).

  Components other than platinum in the metal material mainly composed of platinum are appropriately adjusted for the purpose of adjusting the temperature resistance coefficient (TCR) of the internal resistance wiring 3 and improving heat resistance. Is selected. Examples of components other than platinum include metal materials of platinum group elements such as palladium, rhodium and iridium, and gold. For example, when importance is attached to the linearity of the change of the resistance value with respect to the temperature change of the internal resistance wiring 3, it is preferable that the platinum content is large.

  The metal material mainly composed of platinum contains platinum in a proportion of about 80% by mass or more. Platinum and other components may form an alloy or may exist as crystal grains independent of each other. The internal resistance wiring 3 may contain an additive other than a metal component such as platinum or a metal material containing platinum as a main component. Examples of the additive include inorganic particles similar to those contained in the insulating substrate 1, such as aluminum oxide. The additive is added, for example, for matching the firing shrinkage rate between the internal resistance wiring 3 and the insulating layer 1a.

  The internal resistance wiring 3 is formed by, for example, applying a metal paste prepared by kneading platinum powder together with an organic solvent and a binder in a predetermined pattern on the main surface of the ceramic green sheet to be the insulating layer 1a and simultaneously firing the paste. can do.

  Moreover, the internal resistance wiring 3 does not contain glass. By adopting such a configuration, the resistance of the internal resistance wiring 3 becomes uniform, and the temperature detection accuracy can be increased.

  The resistance value between one end (first end A) of the internal resistance wiring 3 and the opposite end (second end B) is measured by, for example, an external electric circuit. This resistance value changes according to the temperature of the internal resistance wiring 3, and the temperature of the internal resistance wiring 3 changes according to the temperature (external temperature) of the environment where the wiring board 5 or the like is located. The resistance value between the first end A and the second end B of the internal resistance wiring 3 corresponds to the resistance value as the wiring substrate 5. That is, the external temperature is detected by detecting the resistance value between the first and second ends A and B of the internal resistance wiring 3. Specifically, the resistance value of the internal resistance wiring increases as the external temperature rises with respect to the preset initial value at 0 ° C. In the internal resistance wiring mainly composed of platinum, the increase in resistance value is linearly proportional to the increase in temperature. Therefore, an increase in external temperature from 0 ° C. or the like can be easily calculated and detected based on the increase in resistance value from the initial value.

  The external temperature is, for example, the temperature of various combustion exhaust gases, and it may be necessary to detect a high temperature of about several hundred to 1,000 ° C. Since the stability at such a high temperature and the linearity of the electric resistance change according to the temperature are good, the internal resistance wiring 3 is formed of platinum or a metal material containing platinum as a main component. For example, the temperature measuring body 6 is mounted on an external board (not shown) including the above-described resistance detection electric circuit (external electric circuit), and a temperature measurement object exists together with such an external board. It is mounted on the part (gas flow path etc.).

Further, if the internal resistance wiring 3 is exposed to the outside air, it is unnecessary to cause electric damage due to adhesion of foreign matter or damage due to accidental collision with the external substrate or other components mounted on the external substrate. The resistance may change. In order to prevent this, the internal resistance wiring 3 is provided between the plurality of insulating layers 1a. In other words, the internal resistance wiring 3 is provided inside the insulating base 1 and is not exposed to the outside. Further, since the internal resistance wiring 3 is provided inside the insulating base 1, even the internal resistance wiring 3 that does not contain glass is securely held by the insulating base 1.

  The electrode 2 is provided on the main surface of the insulating substrate 1. The electrode 2 is a part for connecting the internal resistance wiring 3 to an external electric circuit. The electrode 2 can be formed by the same method using, for example, the same metal material (platinum or the like) as the internal resistance wiring 3. The electrode 2 in the wiring board 5 of the embodiment is a square pattern made of platinum. The electrode 2 may have other shapes such as a circular shape.

  Since the electrode 2 may be placed in a high-temperature environment as will be described later, the electrode 2 is preferably made of a metal material having high oxidation resistance at high temperatures, such as platinum group metals containing platinum or gold.

  A through conductor, so-called via conductor 4 connects the internal resistance wiring 3 and the electrode 2. In this embodiment, the via conductor 4 penetrates the insulating layer 1a in the thickness direction, for example.

  The via conductor 4 is made of, for example, a conductor material (metal material) whose main component is the same metal material (platinum or the like) as the internal resistance wiring 3. Examples of such a metal material include platinum or a material mainly composed of platinum and added with an inorganic filler such as alumina. For example, when the via conductor 4 and the insulating substrate 1 are formed by simultaneous firing, the inorganic filler is for matching the shrinkage rate and shrinkage behavior of both. Further, the via conductor 4 contains glass in order to increase the bonding strength with the insulating base 1.

  The via conductor 4 can be formed, for example, by filling a metal paste of platinum into a through-hole provided in advance in a ceramic green sheet to be the insulating layer 1a and simultaneously firing. The through hole can be provided in the ceramic green sheet by a machining method such as mechanical drilling using a metal pin or laser beam drilling. In this case, the inorganic filler particles as described above may be added to the metal paste.

  The via conductor 4 has an area in a cross section perpendicular to the length direction (hereinafter simply referred to as a cross-sectional area) larger than the cross-sectional area of the internal resistance wiring 3, and the via conductor compared to the internal resistance wiring 3. It is easy to keep the resistance of 4 small. Since the via conductor 4 is shorter than the internal resistance wiring 3, the resistance value between both ends of the via conductor 4 is originally smaller than that of the internal resistance wiring 3, but the cross-sectional area is relatively large as described above. As a result, the resistance value of the via conductor 4 can be further reduced to a negligible level, for example. Therefore, for example, the possibility that the resistance value between the first end portion A and the second end portion B of the internal resistance wiring 3 is deviated from a predetermined value due to the presence of the via conductor 4 is further reduced, and the temperature detection accuracy is reduced. Can be improved.

  The via conductor 4 and the internal resistance wiring 3 may be connected via the via pad 4a. By adopting such a configuration, it is preferable that the via conductor 4 and the internal resistance wiring 3 are reliably connected even if a positional deviation or the like in the planar direction occurs. The via pad 4a is formed of a conductor material (metal material) whose main component is a metal material (platinum or the like) similar to that of the internal resistance wiring 3, for example.

  According to the wiring board 5 of the present embodiment, the insulating base 1, the electrode 2 provided on the main surface of the insulating base 1, the internal resistance wiring 3 provided inside the insulating base 1, the internal resistance wiring 3, Since the internal resistance wiring 3 does not contain glass and the via conductor 4 contains glass, the internal resistance wiring 3 has an electrical resistance. The via conductor 4 has a relatively large cross-sectional area and is less likely to have a partial change in electrical resistance, so that the temperature detection accuracy can be increased.

  Further, when the insulating substrate 1 contains glass, when the glass content in the insulating substrate 1 is larger than the glass content in the via conductor 4, the glass contained in the via conductor 4 is insulated during firing. It is possible to suppress the outflow to the base 1, and the bonding strength between the insulating base 1 and the via conductor 4 can be increased, which is preferable. In addition, the glass content in the insulating substrate 1 is 4 to 12 wt%, the glass content in the via conductor 4 is 1 to 11 wt%, and the glass content in the insulating substrate 1 is the glass content in the via conductor 4. If it is larger, it becomes possible to effectively suppress the glass contained in the via conductor 4 from flowing out to the insulating base 1 during firing, and the bonding strength between the insulating base 1 and the via conductor 4 can be made high. It is possible and preferable.

  The example shown in FIG. 2 is a partial longitudinal sectional view orthogonal to the length direction of the internal resistance wiring 3 of the wiring substrate 5 shown in FIG. 1, and the internal resistance as in the example shown in FIG. If the inner thickness of the wiring 3 is thicker than the end in the width direction, it is difficult to have a gap between the insulating base 1 and the end in the width direction of the internal resistance wiring 3. Even when the external temperature becomes high and the external temperature is transmitted to the internal resistance wiring 3, the shape of the internal resistance wiring 3 becomes difficult to change, and the electrical resistance of the internal resistance wiring 3 is suppressed from changing. And is preferable.

  Moreover, when the electrode 2 does not contain glass, the metal material of the electrode 2 and the metal material of the via conductor 4 connected to the electrode 2 are favorably connected during firing, which is preferable. Further, the lead terminal 7 described later is preferably connected to the electrode 2 by resistance welding or a brazing method using a brazing material containing gold, which is preferable.

  The temperature measuring body 6 of the embodiment is formed by the above-described wiring board 5 and the lead terminals 7 connected to the electrodes 2 of the wiring board 5. The lead terminal 7 is made of a metal material containing platinum, for example, like the internal resistance wiring 3, and may be made of pure platinum. The connection of the lead terminal 7 to the electrode 2 is performed by joining means such as resistance welding or a brazing method using a brazing material containing gold.

  According to such a temperature measuring body 6, since the wiring board 5 having the above-described configuration is provided, the temperature detection accuracy can be improved.

  For example, in the case of a measuring instrument that measures the temperature of exhaust gas from a device having a combustion part such as an internal combustion engine (gasoline engine, diesel engine, etc.), a gas turbine, a boiler, etc. This is done as follows. That is, first, the temperature measuring body 6 is mounted on the external board including the circuit for measuring electric resistance as described above, and the electrode 2 of the temperature measuring body 6 is electrically connected to a predetermined portion of the circuit of the external board. As the means for electrical connection, there are connection means such as soldering the two, or connecting the lead terminal 7 (not shown in FIG. 1) to the electrode 2 by resistance welding or brazing using a brazing material containing gold. Can be mentioned. Next, the temperature measuring element 6 mounted on the external substrate is mounted in the exhaust gas flow path. In this case, it is sufficient that at least the temperature sensing element can be positioned in the exhaust gas, and other portions of the external substrate do not necessarily have to be positioned in the exhaust gas. Thereafter, the resistance value between the first and second ends A and B of the internal resistance wiring 3 included in the temperature measuring body 6 and the temperature measuring body changes according to the temperature of the exhaust gas, and this resistance value is an electric circuit. Measured with a measurement circuit. Based on the measured resistance value, for example, the temperature of the internal resistance wiring 3 from the relationship between the electrical resistance and the temperature measured in advance, that is, the temperature of the portion where the temperature measuring body 6 including the internal resistance wiring 3 is located. Can be detected.

  The line width of the internal resistance wiring 3 depends on conditions such as the temperature measurement accuracy to be detected, the temperature range, the thickness and length of the internal resistance wiring 3, the distance from the outer periphery of the insulating layer 1a to the internal resistance wiring 3, and the like. It is set as appropriate according to conditions such as productivity and economy.

For example, the temperature range to be detected is a high temperature range of about 500 to 1000 ° C., the internal resistance wiring 3 is made of platinum (so-called pure platinum having a platinum content of 99.99 mass% or more), and the thickness is about 5
If it is about ˜15 μm, the line width of the internal resistance wiring 3 is set to about 20 to 50 μm, for example. In this case, the line width of the portion of the internal resistance wiring 3 along the outer periphery of the insulating layer 1a (that is, the portion close to the outside) may be set to about 50 to 200 μm. As a result, the amount of relative decrease due to platinum sublimation or the like in the portion of the internal resistance wiring 3 close to the outside is reduced, and the accuracy of temperature change detection can be further improved.

  The thickness of the internal resistance wiring 3 is preferably small in order to increase the resistance value (initial value) as much as possible, and is preferably somewhat large in terms of workability when forming the internal resistance wiring 3. Therefore, the thickness of the internal resistance wiring 3 is set to a thickness of, for example, about 5 μm or more.

  In consideration of such thickness setting of the internal resistance wiring 3, it is preferable that the insulating layer 1a is made of a ceramic sintered body and the internal resistance wiring 3 is a thick film conductor. The internal resistance wiring 3 in this case is formed by, for example, simultaneous firing with the insulating base 1 (a plurality of insulating layers 1a). If the internal resistance wiring 3 is a thick film conductor, it is easy to set the thickness to about 5 μm or about 8 μm or more as described above.

  Moreover, since such a relatively thick internal resistance wiring 3, via conductor 4 and electrode 2 can be formed by simultaneous firing with the insulating base 1, the internal resistance wiring 3, via conductor 4 and electrode 2 and the insulating base 1 This is advantageous in terms of bonding strength and productivity as the wiring board 5. Moreover, the pattern of the internal resistance wiring 3 and the electrode 2 can be easily set only by adjusting the printing pattern of the metal paste that becomes the internal resistance wiring 3 and the electrode 2. Therefore, for example, it is advantageous in terms of the degree of freedom in design as the wiring board 5 and the temperature sensing element 6, productivity, and the like.

  With respect to the temperature measuring element 6, for example, a lead terminal 7 for external connection is connected to the electrode 2, or a temperature measuring device (not shown in FIG. 1) is coated with a covering such as a metal casing. May be formed. The temperature measuring device is mounted on an external substrate and measures temperature in the same manner as in the temperature detection by the temperature measuring element 6 described above. In this case, for example, the temperature measuring body 6 is more effectively protected from the external environment by the cover. Further, the mounting is facilitated by the lead terminal 7.

  FIG. 3A is a perspective perspective view showing the temperature measuring device 10 according to the embodiment of the present invention, and FIG. 3B is a plan view of FIG. In FIG. 3, the same parts as those in FIGS. 1 and 2 are denoted by the same reference numerals. In FIG. 3B, the upper insulating layer 1a is omitted for easy viewing. This temperature measuring device 10 includes a temperature measuring body 6 having the above-described configuration and a covering 11 attached to the outer surface of the insulating base 1 so as to cover the electrode 2. In this example, the cover 11 does not overlap the internal resistance wiring 3 when viewed in the thickness direction of the insulating base 1 included in the temperature measuring body 6 in a plan perspective.

  In such a case, since the covering 11 is not interposed between the internal resistance wiring 3 and the outside (external environment for detecting temperature), the external temperature is easily transmitted to the internal resistance wiring 3. The external temperature (heat) is transmitted to the internal resistance wiring 3 through the insulating layer 1a having a smaller thickness than the thickness of the covering 11, that is, a heat transfer distance. Therefore, heat transfer from the outside to the internal resistance wiring 3 is relatively easy, and external temperature detection is easy. Therefore, it is easier to provide the temperature measuring device 10 with high accuracy of external temperature detection.

  In this temperature measuring device 10, the internal resistance wiring 3 has a meander shape, which is more advantageous for increasing the initial resistance value of the internal resistance wiring 3 as much as possible and reducing the size of the temperature measuring device 10. It has become.

The covering body 11 covers, for example, at least the outer surface of the electrode 2 and the surrounding insulating substrate 1 in the temperature measuring body 6 and has a cylindrical or elliptical cylindrical shape. The covering 11 is made of a heat resistant metal such as Inconel. The covering 11 has a shape such as a cylinder, for example. The length of the insulating base 1 protruding from the covering 11 is about 5 mm, and the length of the portion of the insulating base 1 covered by the covering 11 is the length. It is formed with a dimension of about 5 mm. The length of such a covering 11 is about 40 mm, for example.

  In addition, this invention is not limited to the example of the above embodiment, A various change is possible if it is in the range of the summary of this invention. For example, the insulating layer 1a constituting the insulating base 1 may be three or more layers, and the internal resistance wiring 3 provided between the insulating layers 1a may be two or more layers. By adopting such a configuration, the length of the section for measuring the resistance value of the internal resistance wiring 3 becomes longer, and the temperature detection accuracy is further improved. In this case, the internal resistance wirings 3 are connected to each other through the via conductor 4 in the same manner as the connection between the internal resistance wiring 3 and the electrode 2.

  Further, for example, the connecting portion between the electrode 2 and the lead terminal 7 may be covered with a coating material (not shown) such as a glass material. In this case, the connection portion between the electrode 2 and the lead terminal 7 is more effectively protected from the external environment by the coating material. Furthermore, when the coating material is coated from the connection portion between the electrode 2 and the lead terminal 7 to the insulating base 1 that is the periphery of the connection portion between the electrode 2 and the lead terminal 7, the wiring substrate 5 and the lead terminal 7 are coated with the coating material. The connection strength is improved. Examples of the glass material include barium silicate glass and borosilicate glass.

DESCRIPTION OF SYMBOLS 1 ... Insulating base | substrate 1a .... Insulating layer 2 ... Electrode 3 ... Internal resistance wiring 4 ... Via conductor 4a ... Via pad 5 ... Wiring board 6 ... Temperature measuring element 7 ... Lead terminal
10 ... Temperature measuring device
11 ... Coating

Claims (5)

An insulating substrate;
An electrode provided on the main surface of the insulating substrate;
Internal resistance wiring provided inside the insulating substrate;
A via conductor connecting the internal resistance wiring and the electrode;
The internal resistance wiring does not contain glass,
The wiring board, wherein the via conductor contains glass.   The wiring board according to claim 1, wherein an inner thickness of the internal resistance wiring is thicker than an end portion in a width direction.   The wiring board according to claim 1, wherein the electrode does not contain glass. The wiring board according to any one of claims 1 to 3,
A temperature measuring element having a lead terminal connected to the electrode. A temperature measuring device according to claim 4;
And a covering provided on the outer surface of the insulating base so as to cover the electrode.

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