JP2011232232A - Manufacturing method of thermocouple and thermocouple - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a thermocouple capable of accurately measuring a temperature of a fine target member, and having an excellent manufacturability.SOLUTION: Electrodes 11a, 11b are held between thermocouple elements 3a, 3b in such a manner that a contact portion 9 is disposed approximately at a center of the electrode 11a, and an inserting direction into a holding portion of the thermocouple elements 3a, 3b comes on a relief part 15 side. Loads are continuously applied to the electrodes 11a, 11b in a direction of pushing the thermocouple elements 3a, 3b (in the directions of arrows A in the drawing) while the thermocouple elements 3a, 3b are being held between the electrodes 11a, 11b. For example, the loads may be applied by means of a spring, which is disposed behind the electrode 11a or the electrode 11b. A pulse current flows through the thermocouple elements 3a, 3b (the contact portion 9) held between the electrodes 11a, 11b. The pulse current energized between the electrodes 11a, 11b is gradually increased from a lower current side and is applied at several stages.

Description

  The present invention relates to a thermocouple manufacturing method and the like capable of accurately measuring the temperature of a minimal part.

  Conventionally, thermocouples based on the Seebeck effect (thermoelectromotive force) have been used to measure the temperature of various components. The thermocouple measures the temperature from the electromotive force at the contact portion or the joined portion by contacting or joining the tips of different alloy wires.

  On the other hand, when mounting an electronic component on a substrate or the like, solder or the like is used. For joining such electronic components, solder joining is usually performed by supplying a solder paste or the like, then placing the electronic components in a predetermined position, and melting the solder through a reflow furnace. In recent years, lead-free solder is used as solder due to environmental problems.

  For example, Sn-based solder is used as the lead-free solder. Sn-based solder usually melts around 220 ° C. However, the flowability of the melted solder becomes a problem during solder joining, and a temperature error of 1 to 2 ° C. may cause joint failure. For example, the liquidus temperature of the Sn—Ag—Cu alloy solder is 217 to 219 ° C. In this case, the temperature of the soldering part is set 5-10 ° C. higher than the liquidus temperature of the solder. On the other hand, the heat resistance temperature of the mounted component is about 240 ° C. Therefore, as temperature management, the allowable temperature range is significantly narrower than that of conventional Sn-Pb solder. That is, accurate temperature measurement is important for highly accurate temperature control.

  Usually, in order to measure the temperature of the part to be soldered, the above-described thermocouple is fixed to the part to be measured and the temperature is measured. FIG. 9 is a diagram illustrating a state where the thermocouple 30 is installed in the temperature-measured part 37. In the thermocouple 30, the temperature measuring unit 33 is formed in a state where the tips of the thermocouple wires 31a and 31b are in electrical contact. The temperature measuring unit 33 is fixed by a fixing member 35 so as to contact the temperature measured unit 37. In the temperature measuring unit 33, a thermoelectromotive force is generated depending on the temperature of the temperature measuring unit 37, and the temperature of the temperature measuring unit 37 can be known by measuring the thermoelectromotive force.

  As a method for forming the temperature measuring section 33, a method of contacting the thermocouple wires 31a and 31b by twisting, a method of welding by gas (arc) welding, a method of welding by resistance heating, or the like is adopted. ing. The method of twisting and contacting the thermocouple wires 31a and 31b is not suitable for accurate measurement because the contact points are not determined. On the other hand, in the conventional welding method, as shown in the figure, the temperature measuring portion 33 is usually formed in a substantially spherical shape.

  However, since the temperature measuring unit 33 having such a shape is a point contact with the temperature measured unit 37, the temperature measuring unit 33 tends to be in a floating state that is not in direct contact with the temperature measured unit, and accurate temperature measurement is difficult. There is a tendency. Furthermore, in the reflow furnace, the ambient temperature is higher than that of the temperature-measuring part 37. However, since the thermocouple is usually influenced by the temperature of the higher-temperature part, the temperature of the temperature-measuring part 37 is affected by the influence of the atmosphere temperature. It is difficult to know accurately. In addition, the installation range of the fixing member 35 is often limited, and it may be difficult to completely cover the temperature measuring unit 33 with the fixing member 35. In this case, it is difficult to suppress the influence of the ambient temperature. It is. Therefore, a thermocouple capable of more accurate temperature measurement is required.

  As such a thermocouple, there is a thermocouple in which a temperature measuring part is formed by welding and then the temperature measuring part is crushed by rolling to form a disk (Patent Document 1).

JP 2003-344178 A

  However, since a thermocouple like patent document 1 rolls after welding, there exists a problem that the magnitude | size of the temperature measuring part itself becomes large by rolling. For this reason, it is difficult to measure the temperature of the minute temperature-measured part. Moreover, since a rolling process is required separately, a manufacturing man-hour increases. In addition, the welded state after welding is not completely the same, and therefore appropriate rolling conditions are not always the same. For this reason, at the time of rolling, there exists a possibility that the fracture | rupture of a temperature measuring part, generation | occurrence | production of a crack, etc. may occur. In addition, when rolling is performed so as to be thinner than the strand diameter, part of the strand may be broken by rolling.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a thermocouple manufacturing method and the like that can accurately measure a minute temperature-measured portion and is excellent in manufacturability. To do.

  In order to achieve the above-described object, the first invention is a method of manufacturing a thermocouple having a flat surface portion in a temperature measuring part, wherein the vicinity of the tip of a pair of thermocouple wires is brought into contact with each other, The contact portion is sandwiched between a pair of electrodes, a load is applied to the contact portion by the pair of electrodes, a pulse current is passed between the pair of electrodes, and welding is performed while pressurizing the contact portion. A method of manufacturing a thermocouple characterized by the following.

  It is desirable that the pulse current is applied in multiple stages with a current of one pulse or more at each stage so that the current value increases stepwise.

  In the stage before the final stage of the pulse current, the contact part may be temporarily fixed, and in the final stage of the pulse current, the entire cross section of the contact part may be welded.

  The gap between the pair of electrodes when a load is applied to the contact portion may be controlled so as not to become narrower than the wire diameter of the thermocouple element. Further, the pair of thermocouple wires are brought into contact with each other in a direction substantially perpendicular to the sandwiching direction of the pair of electrodes, and a gap between the pair of electrodes that applies a load to the contact portion is the You may control so that it may become narrower than the wire diameter of a thermocouple strand.

  The electrode on one side of the pair of electrodes is a plane electrode having a plane portion sufficiently wide with respect to the contact portion, and a narrow state such as a tapered shape is formed on at least one side surface of the electrode on the other side. The tip portion is formed to have a reduced diameter, and at least a part of the edge portion of the electrode on the other side is formed with a relief portion having a curved shape (for example, a circular arc shape in cross section).

  When the thermocouple element is sandwiched between the pair of electrodes, the contact portion is disposed between the pair of electrodes so that the thermocouple element is positioned at the escape portion.

  According to 1st invention, the thermocouple which has a fine plane part in a temperature measurement part can be easily manufactured by supplying a pulse current several times, providing a load with a pair of electrodes. In particular, resistance heating welding is performed by applying multiple pulse currents, making it easy to control the welding conditions, and overheating due to the effects of variations in welding conditions due to components of the thermocouple wire and the state of installation on the electrodes. Fusing and the like can be prevented.

  In addition, since a load is applied between the electrodes, the melted portion is crushed during welding, and a flat portion can be easily formed. In addition, since welding by pulse current and heavy load are simultaneously performed, it is possible to crush the connection part at the same time as the melting of the connection part starts, so the connection part does not melt excessively and the temperature measuring part is excessive. It can be prevented from becoming large.

  Further, by applying the pulse current so that the current value increases stepwise, overheating of the connecting portion can be prevented, and the influence of variations in welding conditions and the like can be suppressed. In particular, by doing so, for example, when a pulse current is loaded at a predetermined current, only the surface of the thermocouple wire can be partially melted and temporarily fixed, and then at a pulse current load at a slightly higher current. In this case, a part of the cross section of the thermocouple wire is melted, and at this time, the processing of the connection part into a flat surface is started by the load between the electrodes, and the pulse current value is further increased, so that the thermocouple wires are completely Can be welded. Therefore, it is difficult to cause excessive melting or insufficient melting.

  Also, when the connecting portion is made flat, if the thickness of the connecting portion is controlled to be approximately the same as the diameter of the thermocouple strand, disconnection or connection by excessively crushing the connecting portion Defects can be prevented and the thermocouple wires themselves are not crushed.

  In addition, the shape of one of the electrodes has a tapered portion on the side surface and is reduced in diameter, and a relief portion having a curved cross section (for example, an R portion) is formed at a part of the edge portion, so that a concentrated current flows in. Is prevented. In particular, the thermocouple element can be prevented from being melted by arranging the thermocouple element between the electrodes so that the thermocouple element is positioned on the escape portion side. The curved relief portion is not necessarily limited to the arc shape, and may be any curve as long as the concentrated current can be reduced. It is desirable that the width of the end edge portion excluding the relief portion is set to 10 times or less of the thermocouple wire diameter. By doing in this way, the shape (temperature measuring part) after welding of a welding part can be stabilized.

  2nd invention is manufactured using the manufacturing method of the thermocouple concerning 1st invention, and has a plane part in a temperature measurement part, It is a thermocouple characterized by the above-mentioned.

  The thickness of the temperature measuring portion of the thermocouple may be substantially the same as the wire diameter of the thermocouple wire, and the width of the temperature measuring portion may be not more than twice the wire diameter of the thermocouple wire.

  According to the second aspect of the invention, since the fine plane portion is provided, the temperature can be accurately measured even for a minute temperature-measured portion. That is, it is possible to reliably ensure a direct fine contact point with the temperature-measured part without the fixing member interposed by the surface-contact of the temperature-measured part along the shape of the minute temperature-measured part. Therefore, a uniform fixing state can be obtained with a small number of fixing members (within a small fixing member range). Since the response time of the temperature measurement is short, it is possible to accurately follow a minute temperature change of the measured portion. Since the temperature measuring unit is not lifted and exposed, it is not easily affected by the ambient temperature, which is an error factor.

  The thickness of the temperature measuring part is almost the same as the wire diameter of the thermocouple wire. The temperature measuring part is not lifted when it is installed in the temperature measured part. There is no fear of disconnection due to crushing. Also, in this case, if the width of the temperature measuring part is about twice the wire diameter of the thermocouple element (more than the wire diameter), it is convenient to install in a minute temperature-measured part, and not more than twice If so, the present invention can be applied to a smaller temperature-measured part.

  According to the present invention, it is possible to provide a thermocouple manufacturing method and the like that can accurately measure a minute temperature-measured portion and that are excellent in manufacturability.

It is a figure which shows the thermocouple 1, (a) is a top view, (b) is a front view. The figure which shows the manufacturing process of the thermocouple 1. FIG. It is a figure which shows the manufacturing process of the thermocouple 1, (a) is a front view of electrode 11a, 11b, (b) is the top view which saw through the electrode. The figure which shows the load state of a pulse current. It is a figure which shows the shape of the temperature measuring part 5, (a) is a top view, (b) is a front view. The figure which shows the other contact method of the thermocouple strand 3a, 3b. It is a figure which shows the electronic component 17a, (a) is a top view, (b) is a front view, (c) is the B section enlarged view of (b), and shows the state which installed the thermocouple 1 in the connection terminal 19 Figure. The figure which shows the electronic component 17b. The figure which shows the conventional thermocouple 30. FIG.

  Hereinafter, the thermocouple 1 according to the embodiment of the present invention will be described. FIG. 1 is a diagram showing a thermocouple 1, FIG. 1 (a) is a plan view of the thermocouple 1, and FIG. 1 (b) is a front view. The thermocouple 1 is mainly composed of a pair of thermocouple wires 3a and 3b, a covering portion 7, a temperature measuring portion 5 and the like. The thermocouple 1 is used by being connected to an electromotive force measuring device (not shown).

  The thermocouple wires 3a and 3b are appropriately selected according to the type of thermocouple. For example, one thermocouple wire 3a is a chromel wire (Ni—Cr alloy containing 10% Cr) and the other thermocouple is selected. A K-type thermocouple to which an alumel wire (Ni alloy containing Al and Mn) is applied as the pair of wires 3b can be used.

  In addition, in order to minimize the temperature measurement error caused by the thermocouple wire, JIS standard class 1 product or ANSI standard (American National Standards Institute) special product (SLE standard product) ), And a thermocouple wire selected for product-specific variations may be used.

  The diameters of the thermocouple wires 3a and 3b are substantially the same. The wire diameters of the thermocouple wires 3a and 3b are set according to the size of the measurement target part, but in order to accurately measure the temperature of the fine connection part such as an electronic component that is being miniaturized. For example, about 0.08 mm to 0.2 mm can be applied.

  The covering portion 7 is used to insulate the thermocouple wire and improve the mechanical strength. The covering portion 7 is selected according to the heat resistant temperature or the like, and a fluororesin, glass fiber, or the like can be used.

  The temperature measuring unit 5 is a part where the thermocouple wires 3a and 3b come into contact with each other, and a part where thermoelectromotive force is generated. That is, the temperature measuring unit 5 is a part for measuring the temperature of the temperature measurement object.

  The temperature measuring unit 5 has a substantially flat front and back surfaces (both surfaces in the vertical direction when the thermocouple wires 3a and 3b are disposed in the horizontal direction). For example, the shape of the temperature measuring unit 5 is a substantially rectangular shape (the shape of the plane part) in the plan view when it is welded in a wire arrangement as shown in FIG. 1, but may be welded to other shapes. In addition, the shape of the flat part of the temperature measuring part 5 can also be made into a substantially square shape by changing the crossing angle at the time of superimposing the thermocouple strands 3a and 3b in X shape. Thus, by adjusting the angle and the current value, the size and shape of the temperature measuring unit can be appropriately designed. At this time, the cross-sectional shape of the temperature measuring unit is a substantially rectangular shape with the central portion of the side surface slightly spread outward. The temperature measuring unit 5 generates a thermoelectromotive force immediately in response to the heat of the temperature-measuring unit and measures the thermoelectromotive force by bringing the flat surface portion of the temperature-measuring unit 5 into close contact with the temperature-measuring portion. Can measure the temperature of the temperature-measuring part. At this time, since the temperature measuring unit 5 is very fine, the heat capacity is small, and since the temperature measuring unit 5 is in surface contact with the temperature measured unit, the thermal response is extremely high and accurate temperature measurement can be performed.

  Next, a method for manufacturing the thermocouple 1 will be described. FIG. 2 is a diagram showing a manufacturing process of the thermocouple 1. First, as shown in FIG. 2 (a), the covering portion 7 at the tip of each of the thermocouple wires 3a and 3b is removed, and dirt and the like of oil components are removed as necessary, and the thermocouple wires 3a, 3b is arranged substantially in parallel so that the respective tips thereof are directed in substantially the same direction.

  Next, as shown in FIG. 2B, the thermocouple strands 3a and 3b are crossed in an X shape so that the vicinity of the tips overlaps each other. At this time, a contact portion 9 where the thermocouple wires 3a and 3b come into contact with each other is formed at a portion where they overlap each other (near the intersection in the X-shape).

  FIGS. 3A and 3B are diagrams showing a state in which the thermocouple wires 3a and 3b each having an X-shaped contact portion 9 are sandwiched between electrodes, FIG. 3A is a front view, and FIG. 3B is a plan view. It is the figure which saw through the electrode 11a. As shown in FIG. 3A, the electrodes 11a and 11b are provided so as to oppose each other, and the opposing surfaces sandwiching the thermocouple wires 3a and 3b are constituted by substantially parallel planes. The thermocouple wires 3a and 3b are sandwiched between the electrodes in a state where they are stacked in an X shape in the direction of the electrodes 11a and 11b (up and down in the drawing). Therefore, the gap between the electrodes 11a and 11b in this state is about twice the diameter of the thermocouple wire 3a (3b).

  The electrode 11b has a plane having a sufficient area with respect to the size of the joined portion of the thermocouple wires 3a and 3b to be joined, and also serves as a table for positioning and temporarily holding the thermocouple wires. The electrode 11a sandwiches the thermocouple wires 3a and 3b (contact portion 9) from above. The electrode 11a has a tapered portion 13 (narrow portion) formed on at least a part of the side surface. That is, the diameter of the electrode 11a is gradually reduced toward the tip. In the present invention, reducing the diameter does not simply mean the diameter, but means that the width of the electrode in a specific direction is reduced. In addition, a sandwiching surface (a contact surface with the thermocouple wires 3a and 3b, which is a contact surface with the thermocouple wires 3a and 3b, and a lower surface in the drawing) in which both ends of two rectangular sides of the thermocouple wires 3a and 3b in the electrode 11a are combined. ) Is substantially parallel to the electrode 11b and has a smaller area than the clamping surface of the electrode 11b. The length of the clamping surface of the electrode 11a in the narrow width direction is not more than 10 times the size of the connection portion of the thermocouple wires 3a and 3b (substantially equivalent to the size in the width direction of the temperature measuring portion after welding). Desirably, it is more desirably 5 times or less. If the area of the clamping surface of the electrode 11a is too large, the current flows in a distributed manner other than the joint, and the setting state of the thermocouple element, the alignment of the contact part and the welded part, the discharge state during energization, This is because the visibility of the welded state deteriorates.

  When joining a thermocouple element having a diameter of 0.13 mmφ, the electrode 11 a is a rod-shaped electrode using a cylindrical material of about 4 mmφ, for example, and the holding surface is gradually reduced in diameter by the tapered portion 13. The width of the clamping surface may be about 1.5 to 2.5 mm. That is, the width of the tip of the electrode 11a may be about 35 to 65% of the diameter at the base of the electrode 11a. Here, it is desirable that the taper portions 13 are symmetrically formed in the same shape symmetrically, but the taper angles of the two tapers facing each other may be formed differently. In this case, since the shape of the base portion of the electrode 11a is also an object, positioning at the time of setting the thermocouple wire is easy. However, the shape of the base portion of the electrode 11a is described later by forming the taper angle differently. Alternatively, it may be formed asymmetrically as shown in FIG.

  An escape portion 15 is formed on at least a part of the end edge of the electrode 11a (at least a part of the edge between the sandwiching surface and the side surface). The escape portion 15 is a portion having an R shape with a circular arc cross section. That is, in the escape portion 15, the clamping surface and the side surface are gently connected. In addition, the escape part should just be about a curvature radius of about 0.5 mm, for example.

  When the thermocouple strands 3a and 3b are sandwiched between the electrodes 11a and 11b, the contact portion 9 is installed so as to be substantially at the center of the electrode 11a (clamping surface), and further, the thermocouple strands 3a and 3b It arrange | positions so that the insertion direction to a clamping part may become the escape part 15 side. That is, the escape portion 15 is provided at the edge portion (right side of the electrode 11a in the drawing) of the electrode 11a where the base side of the thermocouple wires 3a and 3b (right side in the drawing and opposite to the tip side) is located. It is formed. Since the thermocouple wires 3a and 3b come into contact with the relief portion 15 that is a gentle edge, it is possible to prevent the thermocouple wires 3a and 3b from being disconnected by a concentrated current.

  The electrodes 11a and 11b are continuously loaded in the direction in which the thermocouple wires 3a and 3b are crushed (in the direction of arrow A in the figure) with the thermocouple wires 3a and 3b sandwiched therebetween. For example, a spring may be arranged behind the electrode 11a or the electrode 11b and a load may be applied by the spring. For example, the load is about 2 kgf.

  FIG. 4 is a conceptual diagram showing currents flowing through the electrodes 11a and 11b. A plurality of pulse currents flow through the thermocouple wires 3a and 3b (contact portion 9) sandwiched between the electrodes 11a and 11b. As the pulse current, for example, 1 Hz of 50 Hz alternating current is stored in a capacitor or the like as power for generating a pulse current, and a part of the power of 1 Hz of the power stored in the capacitor is extracted and supplied as a pulse current. Can be generated by doing so. In this case, for example, the energization time of one pulse is 1/50 second or less.

The pulse current supplied between the electrodes 11a and 11b is gradually increased from the low current side and loaded multiple times. As the stage of the pulse current, the maximum current of the welding machine may be divided into about 10 equal parts, and the current may be changed to 10 stages, or the stage may be changed more finely.
For example, as shown in FIG. 4A, for a welding machine with a maximum current of 450 A, one stage (S 1 in the figure) is set to 3 A, and from stage 1 (3 A) to stage n (Sn in the figure) (3 nA) However, normally, as shown in FIG. 4B, it is also possible to flow the pulse current multiple times at each stage. 4A and 4B can be combined, and the pulse current can be applied at least once at each stage of the current value.

  The energization conditions are set as appropriate according to the material, wire diameter, etc. of the thermocouple element. For example, when an alumel-chromel wire of 0.2 mmφ is used, the current value is an electrode of a commercial power supply of 100 volts. The current value is 10% level of the maximum current because the current value is 10% of the maximum current, because the current value is 40% level or more when the cycle of the thyristor phase control method is 100% with respect to the current amount of 450A effective at short circuit. To the fourth stage at the 35% level of the maximum current, and a plurality of times in a predetermined time step so that welding is performed while checking the welding state of the thermocouple wire. In this case, if necessary, the welding may be completely performed by repeatedly applying the current of Step 5 (40% level of the maximum current) 2 to 3 times. Here, in energization by the thyristor phase control method, the relationship between the scale position of the current adjustment knob and the current magnitude with respect to the maximum current value is not necessarily linear. Also, the current value during welding naturally varies depending on the diameter of the wire to be welded.

  Therefore, for example, when an alumel-chromel wire of 0.13 mmφ is used, it melts at a current value of 25% or higher, so welding is performed at a lower current value, but about 20% of the maximum current of the welder is reduced. In this case, the maximum current value is set, for example, the current value is divided into a first stage at a level of 10% of the maximum current and a fourth stage at a level of 20% of the maximum current, and the current value is made to flow multiple times step by step. Welding while checking the welding status of the thermocouple wires.

  The reason why the pulse current is applied step by step is as follows. Usually, when electricity is passed between the electrodes, Joule heat is generated by the resistance of the thermocouple wire. The thermocouple strand is melted and joined by this heat. Here, when energization is continuously performed, the temperature of the thermocouple wire rapidly increases, and melting proceeds at a stretch. For this reason, there exists a possibility of a fusing and a fusion | melting part will be formed over a wide range.

  On the other hand, by using a pulse current, it is possible to control the welding state more finely by applying a current for each pulse so as not to generate a heat quantity enough to completely melt the thermocouple wire. . At this time, by gradually increasing the current, it is possible to control the preheating stage to the temporary fixing stage to the partial melting stage to the complete welding stage in one or a plurality of stages. For this reason, a fusion | melting part is not formed at a stretch, and there is also no fear of fusing. Moreover, since melting is performed in stages, it is possible to prevent the melting range from becoming excessively large and the molten shape from being uncontrollable.

  For example, in FIG. 4, the remaining heat of the thermocouple wire is generated by energization of S1, only the surface of the thermocouple wire is melted and temporarily fixed in S2, and partial welding or full cross section of the thermocouple wire is performed in Sn. Can be controlled to be performed. Such a pulse current condition may be determined in advance by experiments or the like with respect to the thermocouple element to be used, and the pulse current application condition may be adjusted while manufacturing while watching the welding state. At this time, since the current is a pulse, excessive heat generation can be prevented.

  As described above, when a pulse current is applied, a load is continuously applied between the electrodes 11a and 11b. Accordingly, when a part of the thermocouple wires 3a and 3b starts to melt, the melted portion is crushed.

  FIG. 5 is a diagram showing a state where welding of the thermocouple wires 3a and 3b is completed. FIG. 5 (a) is a plan view (a perspective view of the electrode 11a), and FIG. 5 (b) is a front view. When the welding is completed, the extra length portion 16 at the tip of the temperature measuring unit 5 is removed. FIG. 5B is a diagram showing a state where the extra length portion 16 is removed.

  The contact portions of the thermocouple wires 3a and 3b are crushed by the electrodes 11a and 11b while being gradually melted by the pulse current. Therefore, the gap between the electrodes 11a and 11b gradually decreases from about twice the wire diameter of the thermocouple element 3a (3b). On the other hand, the thickness between the electrodes 11a and 11b is controlled so as not to be narrower than the wire diameter of the thermocouple element 3a (3b). For example, an insulating spacer having a thickness substantially the same as the diameter of the thermocouple wire is placed between the electrodes 11a and 11b, and the distance between the electrodes is limited so as not to be narrowed.

  Therefore, as shown in FIG. 5B, the thickness T of the welded temperature measuring section 5 is substantially the same as the wire diameter of the thermocouple element 3a (3b). The width W and the length L of the temperature measuring unit 5 are about twice the diameter of the thermocouple strand 3a (3b). This is because if it is too large, it will be difficult to install in a minute temperature-measured part. The thermocouple 1 is formed by the above method.

  FIG. 6 is a diagram showing another embodiment of a method of contacting the thermocouple wires 3a and 3b when installed between the electrodes 11a and 11b. As described above, instead of the X-shaped contact method, as shown in FIG. 6A, the side surfaces of the thermocouple wires 3a, 3b are perpendicular to the clamping direction of the electrodes 11a, 11b. The contact portion 9 may be formed by contacting the I in an I shape.

  Further, as shown in FIG. 6 (b), it is provided side by side in a direction perpendicular to the sandwiching direction of the electrodes 11a and 11b, and the end faces of the thermocouple wires 3a and 3b are brought into contact with each other to be substantially C-shaped, The contact portion 9 may be formed. In the case of FIG. 6A and FIG. 6B, the side surface or end surface of the thermocouple element 3a (3b) is abutted and brought into contact with each other. It is lower than the diameter, and the welded portion can be formed into a rectangular shape by applying pressure, and the cross-sectional shape at this time is a cross-section having a shape in which the center of the side surface of the cross-section slightly extends outward. Although not shown in the drawing, positioning as shown in FIGS. 6 (a) and 6 (b) is difficult compared with the case of X-shaped welding. It is also possible to perform welding by temporarily fixing or welding after lightly twisting contact. Also in these cases, the temperature measuring unit plane can be rectangular. As described above, both contact surfaces are melted to form contacts that are slightly thinner than the wire diameter. In these cases, similar weld contacts can be formed. Further, even in the case of C-type contact, it is also possible to smash the tip very slightly and to overlap and weld the crushed portions. Even in this case, a welding contact having a substantially rectangular plane portion is obtained. In addition, when the end portions of thermocouple wires are overlapped and welded, the thermocouple wires to be overlapped do not have to be completely overlapped on the same line, and are overlapped so that the respective axial directions are at a slight angle. May be.

  Next, a method for using a thermocouple will be described. 7A and 7B are diagrams showing the electronic component 17a, where FIG. 7A is a plan view and FIG. 7B is a front view. The electronic component 17a is a so-called QFP (Quad Flat Package), and a plurality of connection terminals 19 are formed on four sides. The connection terminals 19 are soldered to the substrate or the like. Here, the width w1 of the connection terminal 19 is, for example, about 0.2 to 0.25 mm.

  FIG.7 (c) is the B section enlarged view of FIG.7 (b). For example, the thermocouple 1 is directly installed on the connection terminal 19 in order to measure and control the solder temperature. On the temperature measurement part 23 (temperature measurement object part of the connection terminal 19), it arrange | positions so that the plane part of the temperature measurement part 5 may contact, and the covering member is fixed by the fixing member 21. As the fixing member 21, a heat resistant adhesive tape, a paste-like resin, an Ag paste, or the like is used. The fixing member 21 only needs to be able to fix the thermocouple during measurement, easily remove the thermocouple, and suppress the influence of the ambient temperature and the like.

  Since the temperature measuring unit 5 has a width (length) about twice the wire diameter of the thermocouple wire 3a (3b), for example, if a thermocouple wire of 0.08 to 0,13 mmφ is used, The size is about 0.16 to 0.26 mm. Therefore, it can be installed on the fine connection terminals 19 and is not short-circuited to other adjacent connection terminals.

  FIG. 8 is a diagram showing an electronic component 17b that is also a BGA (Ball Grid Array). A plurality of solder balls 25 are formed on the lower surface of the electronic component 17b. The width w2 of the solder ball 25 is about 0.2 to 0.3 mm. Therefore, the temperature measuring part 5 of the thermocouple 1 is sufficiently small even with respect to such a solder ball 25, and the temperature can be reliably measured.

  As described above, according to the present embodiment, it is possible to easily obtain a thermocouple having a minute temperature measuring unit on which a plane is formed. Moreover, since welding and crushing are performed simultaneously, the process is simple, and the temperature measuring unit 5 can be formed very minutely in combination with welding by a pulse current. Further, it is possible to reliably form a temperature measuring part having a flat part.

  Since the temperature measuring unit 5 is substantially the same in thickness as the thermocouple wire, the temperature measuring unit does not rise when installed in the temperature measured unit. In addition, since the temperature measuring unit is minute, the heat capacity is small, and furthermore, since it is in surface contact, it has excellent heat responsiveness and can be easily covered with a fixing member or the like, so that it is hardly affected by the atmosphere. For this reason, high-precision temperature measurement of about ± 1 ° C. is possible with respect to the conventional thermocouple accuracy (± 2 ° C.).

  Also. By forming the tip of the electrode to have a reduced diameter, it is possible to minimize energization to the welded part and to form a relief part at the contact part with the thermocouple wire that is the joined part , The flow of concentrated current can be suppressed. For this reason, the fusion | melting etc. of a thermocouple strand can be prevented.

  In addition, since the tip of the electrode is reduced in diameter, the welding state of the thermocouple wire can be easily visually confirmed. For this reason, for example, it is also possible to determine that the welding time is the time when the surplus length portion is moved by applying a pulse current while visually confirming the surplus length portion or the like of the thermocouple wire.

  As described above, the soldering condition (temperature) of the minute electronic component can be grasped more accurately by the temperature measuring unit having a fine and flat surface, and the defective soldering of the electronic component due to the temperature condition can be prevented. . In particular, it is easy to control the volume and shape of the temperature measuring unit because a pulse current is applied while applying pressure. Also, since the temperature measuring unit has a substantially rectangular plane, the temperature measuring unit and the temperature measuring unit are in contact with each other. If the area is the same, the entire width (full length) of the temperature measuring unit can be reduced with respect to the circular shape, and it is possible to deal with a finer temperature-measured unit.

  As mentioned above, although embodiment of this invention was described referring an accompanying drawing, the technical scope of this invention is not influenced by embodiment mentioned above. It is obvious for those skilled in the art that various modifications or modifications can be conceived within the scope of the technical idea described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

  For example, each step of the pulse current need not always be increased at a constant current width, and the increase width may be changed for each step. In addition, at a predetermined stage, a plurality of pulse currents may be applied with the same current value. Compared with the case where a constant current is continuously supplied, by using a pulse current, rapid heating and melting can be prevented, and the melting state can be controlled. Needless to say, the present invention can be applied not only to K type thermocouples but also to other types of thermocouples such as E type, J type, and T type.

1 ..... Thermocouple 3a, 3b ..... Thermocouple element 5 ..... Temperature measuring part 7 ..... Covering part 9 ..... Contact part 11a, 11b ..... Electrode 13 ....... Taper part 15 ... ... Escape part 16 ......... Excess length parts 17a, 17b ......... Electronic component 19 ......... Connection terminal 21 ......... Fixing member 23 ......... Temperature measured part 25 ......... Solder ball 30 ......... Thermoelectric Pairs 31a, 31b ......... thermocouple wire 33 ......... temperature measuring unit 35 ......... fixing member 37 ...... temperature-measured unit

Claims (9)

A method of manufacturing a thermocouple having a flat surface portion in a temperature measuring portion,
Contact the vicinity of the tip of a pair of thermocouple wires,
The contact portion between the thermocouple wires is sandwiched between a pair of electrodes,
A method of manufacturing a thermocouple, wherein a load is applied to the contact portion by the pair of electrodes, a pulse current is passed between the pair of electrodes a plurality of times, and the contact portion is welded while being pressed.   2. The method of manufacturing a thermocouple according to claim 1, wherein a plurality of stages of currents of one pulse or more are applied in each stage so that the current value of the pulse current increases in stages.   3. The method of manufacturing a thermocouple according to claim 2, wherein the contact portion is temporarily fixed before the final stage of the pulse current, and the entire cross section of the contact portion is welded at the final stage of the pulse current. .   The gap between the pair of electrodes for applying a load to the contact portion is controlled so as not to be narrower than the wire diameter of the thermocouple wire. The manufacturing method of the thermocouple in any one of.   The pair of thermocouple wires are brought into contact with each other in a direction substantially perpendicular to the holding direction of the pair of electrodes, and a gap between the pair of electrodes that applies a load to the contact portion is the thermocouple. The method of manufacturing a thermocouple according to any one of claims 1 to 3, wherein control is performed so that the wire diameter is narrower than a wire diameter.   The electrode on one side of the pair of electrodes is a plane electrode having a plane portion that is sufficiently wide with respect to the contact portion, and at least one side surface of the electrode on the other side is narrower toward the tip. 6. The relief portion having a curved cross-section is formed in at least a part of the edge portion of the electrode on the other side. 6. The manufacturing method of the thermocouple of description.   The contact portion is disposed between the pair of electrodes so that the thermocouple strand is positioned at the escape portion when the thermocouple strand is sandwiched between the pair of electrodes. Item 7. A method for manufacturing a thermocouple according to Item 6.   A thermocouple manufactured using the method of manufacturing a thermocouple according to claim 1, wherein the thermometer has a flat surface portion.   The thickness of the temperature measuring part of the thermocouple is substantially the same as the wire diameter of the thermocouple wire, and the width of the temperature measuring part is not more than twice the wire diameter of the thermocouple wire. The thermocouple according to claim 8.

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