Calibration system and method for radiation thermometer in laser soldering device, and manufacturing method for calibration thermometer

Abstract

To enable a radiation thermometer to be calibrated easily in a short time without using a black body furnace.SOLUTION: A calibration system 25 is composed of an irradiation head 6 for radiating laser light, a radiation thermometer 7 for contactlessly measuring the temperature of a solder 20 for temperature measurement, a thermometer 15 for calibration which is installed to a soldering device, and a controller 10 to which a program for calibration is inputted. The thermometer 15 for calibration includes a body 16, a measurement chamber 17 formed on the upper surface of the body 16, the solder 20 for temperature measurement which is accommodated inside the measurement chamber 17, a temperature sensor 19 for directly measuring by contact the temperature of the solder 20 for temperature measurement, and a transparent and heat-resistant oxidation prevention glass 23 for preventing the oxidation of the solder 20 for temperature measurement by contact with the atmospheric air, with the solder 20 for temperature measurement adhered tightly without gaps to the underside of the oxidation prevention glass 23.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a calibration system and a calibration method for a radiation thermometer in a laser soldering device. and a method for manufacturing a calibration thermometer It is related to. [Background technology]

[0002] In laser soldering devices that use laser light to solder electronic components and the like to printed circuit boards, the temperature of the molten solder is measured with a radiation thermometer, and the temperature information is fed back to adjust the output of the laser light. Therefore, the solder temperature measured by the radiation thermometer is directly linked to the output of the laser light, which has a significant impact on the accuracy of the soldering. Therefore, it is important to manage the measurement accuracy of the radiation thermometer and regularly calibrate it to maintain constant measurement accuracy.

[0003] The calibration of the radiation thermometer is usually performed using a blackbody furnace, as described in Patent Document 1, for example. When using a blackbody furnace in this way, the blackbody furnace needs to be installed in an appropriate position on the soldering device during calibration, but selecting the installation location and installing it are not easy, and after installation, it takes 30 minutes or more to heat the blackbody furnace to the required temperature. Therefore, if it becomes necessary to calibrate the radiation thermometer during the soldering process, the soldering must be interrupted for a long time, resulting in a decrease in production efficiency. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-81816 Summary of the Invention [Problem to be solved by the invention]

[0005] A technical object of the present invention is to enable calibration of a radiation thermometer to be performed easily and quickly without using a blackbody furnace. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the present invention provides a calibration system for calibrating the radiation thermometer in a laser soldering apparatus having an irradiation head that irradiates a soldering portion with laser light, a radiation thermometer that measures the temperature of the solder by receiving infrared light radiated from the solder that has been supplied to the soldering portion and melted by heating, and a controller that controls the entire apparatus, the calibration system comprising the irradiation head and the radiation thermometer, a calibration thermometer installed in the laser soldering apparatus, and the controller into which a calibration program has been input, The calibration thermometer has a body, a measurement chamber formed on the upper surface of the body, a temperature measurement solder that is the temperature measurement object housed in the measurement chamber, and a temperature sensor that is connected to the temperature measurement solder to directly measure the temperature of the temperature measurement solder, the temperature sensor being made up of a thermocouple in which two different metal wires are connected to each other and the connection point is made into a temperature measurement part for temperature measurement, the temperature measurement solder is joined to the temperature measurement part, and transparent, heat-resistant, oxidation-resistant glass is attached to the measurement chamber so as to cover the temperature measurement solder in order to prevent oxidation of the temperature measurement solder due to contact with the atmosphere. and the laser light output from the irradiation head of the laser soldering device is irradiated onto the temperature-measuring solder through the oxidation-resistant glass, The temperature measuring solder is tightly adhered to the lower surface of the oxidation resistant glass without any gaps.

[0007] In the present invention, A partition plate on which the temperature-measuring solder is placed is provided within the measurement chamber, and the lower surface of the anti-oxidation glass and the upper surface of the partition plate are formed of a material that is not wettable by the temperature-measuring solder. In addition, a hole is formed in the partition plate at the location where the temperature-measuring solder is placed, and the temperature-measuring portion of the temperature sensor is bonded to the bottom surface of the temperature-measuring solder through the hole.

[0008] In the present invention, the temperature-sensing solder is bonded to the glass plate by ultrasonic soldering. The calibration thermometer is installed in the vicinity of the soldering area of ​​the laser soldering apparatus where the soldering portion is arranged.

[0009] Furthermore, according to the present invention, there is provided a method for calibrating the radiation thermometer using the calibration system, comprising: irradiating the temperature-measuring solder of the calibration thermometer with laser light from the irradiation head to melt the temperature-measuring solder; measuring the temperature of the melted temperature-measuring solder with the temperature sensor and inputting the measured value to the controller; and receiving infrared light emitted from the temperature-measuring solder with the radiation thermometer, thereby measuring the temperature of the temperature-measuring solder with the radiation thermometer and inputting the measured value to the controller; calculating an emissivity offset amount in the controller according to the difference between the value measured by the temperature sensor and the value measured by the radiation thermometer; and offsetting the emissivity of the radiation thermometer based on the calculated emissivity offset amount. [Effects of the Invention]

[0010] According to the present invention, by using the calibration thermometer, calibration of a radiation thermometer can be performed very simply and in a short time (about 20-30 seconds) without using a blackbody furnace. Moreover, the calibration thermometer can be permanently installed in an appropriate location of the laser soldering device, for example, near the soldering area, so installation is simple. Furthermore, the output of the laser light irradiated on the calibration thermometer during calibration can be as low as a few watts, so power consumption is low and it is economical. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a front view of a soldering robot equipped with a calibration thermometer according to the present invention. [Figure 2] FIG. 2 is a plan view of FIG. [Figure 3] FIG. 1 is a perspective view of a calibration thermometer according to the present invention. [Figure 4] FIG. 4 is a central longitudinal cross-sectional view of FIG. 3. [Figure 5] FIG. 1 is a configuration diagram of a calibration system for a radiation thermometer. [Figure 6] 10 is a flowchart illustrating a method for calibrating a radiation thermometer. DETAILED DESCRIPTION OF THE INVENTION

[0012] An embodiment of a calibration thermometer according to the present invention will be described in detail below with reference to the drawings. Figures 1 and 2 show an example of a laser soldering apparatus equipped with a radiation thermometer calibration system according to the present invention. The soldering apparatus 1 is a gantry-type soldering robot, and includes a board-shaped base 2, left and right support columns 3, 3 extending from the base 2, first guides 4a disposed at the upper ends of the left and right support columns 3, 3 so as to extend in the front-to-rear direction (Y direction) of the apparatus, a second guide 4b spanning between the left and right first guides 4a, 4a and displaceable in the front-to-rear direction along the first guide 4a, a slide member 5 displaceable in the left-to-right direction (X direction) along the second guide 4b, an irradiation head 6 supported by the slide member 5, a radiation thermometer 7 supported by the irradiation head 6 or the slide member 5, a table 8 on which a printed circuit board 9 to be soldered is placed, and a controller 10 for controlling the entire soldering apparatus 1. The irradiation head 6 is connected to a laser oscillator 12 through an optical fiber 11, and the laser oscillator 12 and the radiation thermometer 7 are connected to the controller 10 through electric cables 12a and 7a, respectively.

[0013] When the soldering device 1 is used to solder a soldering target placed in the soldering area 8a on the table 8, i.e., a printed circuit board 9 and an electronic component 13, the irradiation head 6 irradiates the soldering portion with laser light L, melting the solder supplied from a solder supply nozzle (not shown). At this time, the temperature of the soldering portion, i.e., the temperature of the molten solder, is measured by the radiation thermometer 7, and the measurement result is fed back to the controller 10. The laser oscillator 12 is controlled in accordance with the measurement result, thereby adjusting the output of the laser light L irradiated from the irradiation head 6. The emissivity of the radiation thermometer 7 is set to that of tin, which is the main component of solder.

[0014] The measurement accuracy of the radiation thermometer 7 has a significant effect on the accuracy of soldering, so it is necessary to maintain a constant accuracy by periodically calibrating it. For this reason, the soldering apparatus 1 is provided with a calibration thermometer 15, which is used when calibrating the radiation thermometer 7, installed near the soldering area 8a on the table 8.

[0015] 3 and 4, the calibration thermometer 15 has a square block-shaped body 16. The body 16 can be made of a non-metallic inorganic material such as fine ceramics that is heat-resistant and non-conductive.

[0016] A measurement chamber 17 consisting of a square depression is formed on the upper surface of the body 16, and a thin, narrow partition plate 18 is attached inside the measurement chamber 17 so as to span between the left and right chamber walls, a temperature sensor 19 is attached to the underside of the partition plate 18, and temperature-measuring solder 20, the temperature of which is to be measured by the temperature sensor 19, is placed on the upper surface of the partition plate 18. However, the partition plate 18 may have a width approximately the same as the width of the measurement chamber 17, and may completely separate the measurement chamber 17 into upper and lower parts.

[0017] The temperature sensor 19 is made up of a thermocouple in which two dissimilar metal wires 19a, 19b are connected to each other, with the connection point serving as a temperature measuring part 19c for measuring temperature. The temperature measuring part 19c is exposed on the upper surface of the partition plate 18 through a hole 18a formed in the partition plate 18, and the temperature measuring solder 20 is attached to this temperature measuring part 19c by soldering. The member designated by the reference numeral 21 in the figure is a connector for connecting a lead wire 19d connected to the temperature sensor 19 to the controller 10 (see FIG. 2). The partition plate 18 is made of a material that is not wettable by solder, so even if the temperature-measuring solder 20 is heated and melted by laser light when calibrating the radiation thermometer 7 (see Figure 2), the melted temperature-measuring solder will not wet and spread over the partition plate 18.

[0018] A transparent, heat-resistant oxidation-resistant glass 23 is attached to the upper opening 17a of the measurement chamber 17 so as to cover the temperature-sensing solder 20 in order to prevent oxidation of the temperature-sensing solder 20 due to contact with the atmosphere, and the temperature-sensing solder 20 is tightly adhered to the underside of the oxidation-resistant glass 23 by ultrasonic soldering so that no gaps are formed between the temperature-sensing solder 20 and the oxidation-resistant glass 23. Because the surface of the oxidation-resistant glass 23 is not wettable by solder, even if the temperature-sensing solder 20 is heated and melted by laser light during calibration of the radiation thermometer 7, the temperature-sensing solder 20 will not wet and spread along the underside of the oxidation-resistant glass 23. The oxidation-resistant glass 23 may be airtightly attached to the opening 17a so as to isolate the measurement chamber 17 from the atmosphere.

[0019] When the radiation thermometer 7 is calibrated using the calibration thermometer 15, the following steps are performed: to In this case, the irradiation head 6 and the radiation thermometer 7 move from the soldering position shown in the figure to the position (calibration position) where the calibration thermometer 15 is placed. This constitutes a calibration system 25 for the radiation thermometer shown in Fig. 5. This calibration system 25 is composed of the irradiation head 6 and the radiation thermometer 7, the calibration thermometer 15, and the controller 10 into which a calibration program has been input.

[0020] The calibration of the radiation thermometer 7 by the calibration system 25 is carried out, for example, before the start of a soldering operation, as follows: The calibration method will be described with reference to FIGS. 6, when calibration is started in step S1, in step S2, laser light L is irradiated from the irradiation head 6 onto the temperature-measuring solder 20 of the calibration thermometer 15 through the oxidation-resistant glass 23. The intensity (output) of the laser light L at this time is set to a low output of, for example, about several watts.

[0021] Subsequently, the temperature-measuring solder 20 is heated and melted by irradiation with the laser light L (step S3), and the temperature of the melted temperature-measuring solder 20 is directly measured by the temperature sensor 19, whose temperature measuring unit 19c is connected to the temperature-measuring solder 20 (step S4), and the measured value T1 (first measured value) is input to the controller 10. At the same time, the temperature of the temperature-measuring solder 20 is also measured by the radiation thermometer 7 when infrared light emitted from the temperature-measuring solder 20 is received by the radiation thermometer 7 through the oxidation-resistant glass 23 (step S5), and the measured value T2 (second measured value) is input to the controller 10. It is desirable that the first measured value T1 and the second measured value T2 be displayed on a display unit (not shown) provided in the controller 10 or provided in a position separate from the controller 10 so that the operator can confirm them.

[0022] Furthermore, even if the temperature-measuring solder 20 is heated and melted by the laser light L, the surface of the partition plate 18 and the surface of the antioxidant glass 23 are not wettable by the solder, so the solder does not spread along the surfaces of the partition plate 18 and the antioxidant glass 23, but remains in the position it was in before it melted.

[0023] Next, after the irradiation of the laser light is stopped in step S6, the first measurement value T1 from the temperature sensor 19 and the second measurement value T2 from the radiation thermometer 7 are compared in step S7 in the controller 10, and if the second measurement value T2 is smaller than the first measurement value T1, an emissivity offset amount according to the difference between the two (measured temperature difference) is calculated (step S8), and then, in step S9, the emissivity of the radiation thermometer 7 is automatically offset according to the calculated emissivity offset amount. That is, the emissivity of the radiation thermometer 7 is rewritten to an emissivity such that the second measurement value T2 from the radiation thermometer 7 is equal to the first measurement value T1 from the temperature sensor 19, thereby completing the calibration of the radiation thermometer 7. If there is no difference between the first measurement value T1 from the temperature sensor 19 and the second measurement value T2 from the radiation thermometer 7, the emissivity of the radiation thermometer 7 is not rewritten and the calibration ends. When the calibration of the radiation thermometer 7 is completed, the irradiation head 6 and the radiation thermometer 7 are returned to the soldering position shown in FIGS. 1 and 2, and the soldering operation is started.

[0024] Here, in step S7, if the second measurement value T2 from the radiation thermometer 7 is smaller than the first measurement value T1 from the temperature sensor 19 by a certain value or more, it is assumed that the protective glass attached to the front of the radiation thermometer 7 is contaminated with fumes or flux adhering thereto during soldering. Therefore, the calibration process can be temporarily interrupted, and the protective glass can be wiped to remove the contamination, and then the calibration process can be resumed from step S2.

[0025] In this way, by calibrating the radiation thermometer 7 using the calibration thermometer 15, the calibration can be easily performed in a very short time (about 20 to 30 seconds) compared to when a blackbody furnace is used. Therefore, even during the soldering process, the radiation thermometer 7 can be calibrated without interrupting the soldering work, such as when replacing the printed circuit board 9 or when one batch process is completed and the next batch process is started. Moreover, the calibration thermometer 15 can be installed constantly near the soldering area 8a where the printed circuit board 9 is placed during soldering, making installation easier than when a blackbody furnace is used.

[0026] Furthermore, by knowing that there is a difference between the first measurement value T1 from the temperature sensor 19 and the second measurement value T2 from the radiation thermometer 7, it is possible to know if there is an abnormality in the radiation thermometer 7 or if there is dirt on the protective glass attached to the front of the radiation thermometer 7 to prevent fumes, flux, etc. from adhering, thereby improving maintainability. Furthermore, the output of the laser light L irradiated onto the calibration thermometer 15 can be as low as a few watts, which reduces power consumption and is economical. [Explanation of symbols]

[0027] 1 Soldering equipment 6 irradiation head 7 Radiation thermometer 8a Soldering area 15 Calibration thermometer 16 Body 18 Divider 18a hole (hole) 19 Temperature Sensor 19a,19b Metal wire 19c Temperature measuring part 20 Temperature measuring solder 23 Anti-oxidation glass 25 Calibration System

Claims

1. A calibration system for calibrating the radiation thermometer in a laser soldering apparatus having an irradiation head that irradiates a soldering portion with laser light, a radiation thermometer that measures the temperature of the solder by receiving infrared light emitted from the solder that has been supplied to the soldering portion and melted by heating, and a controller that controls the entire apparatus, comprising: the calibration system is composed of the irradiation head and the radiation thermometer, a calibration thermometer installed in the laser soldering apparatus, and the controller into which a calibration program is input, The calibration thermometer has a body, a measurement chamber formed on the upper surface of the body, a temperature measurement solder that is the temperature measurement target accommodated in the measurement chamber, and a temperature sensor that is connected to the temperature measurement solder to directly measure the temperature of the temperature measurement solder, The temperature sensor is made of a thermocouple in which two different metal wires are connected to each other, and the connection point serves as a temperature measuring part for measuring temperature, and the temperature measuring solder is joined to the temperature measuring part, a transparent, heat-resistant, oxidation-resistant glass is attached to the measurement chamber so as to cover the temperature-measuring solder to prevent the temperature-measuring solder from being oxidized due to contact with the atmosphere; The laser light output from the irradiation head of the laser soldering device is irradiated onto the temperature-measuring solder through the oxidation-resistant glass, The temperature measuring solder is tightly adhered to the lower surface of the oxidation-resistant glass without any gaps. A calibration system for a radiation thermometer in a laser soldering device, comprising:

2. A partition plate on which the temperature-measuring solder is placed is provided in the measurement chamber, the lower surface of the oxidation-resistant glass and the upper surface of the partition plate are formed of a material that is not wettable by the temperature-sensing solder; 2. The calibration system of claim 1.

3. A hole is formed in the portion of the partition plate where the temperature measuring solder is placed, The temperature measuring portion of the temperature sensor is bonded to the bottom surface of the temperature measuring solder through the hole.

3. The calibration system of claim 2.

4. A method for manufacturing the calibration thermometer in the calibration system according to any one of claims 1 to 3, comprising: A method for manufacturing a calibration thermometer, wherein the temperature measuring solder is bonded to the anti-oxidation glass by ultrasonic soldering.

5. 4. The calibration system according to claim 1, wherein the calibration thermometer is installed in the vicinity of a soldering area of ​​the laser soldering apparatus in which the soldering portion is arranged.

6. A method for calibrating the radiation thermometer using the calibration system according to any one of claims 1, 2, 3 and 5, characterized in that the temperature measurement solder of the calibration thermometer is melted by irradiating the temperature measurement solder with laser light from the irradiation head, the temperature of the melted temperature measurement solder is measured by the temperature sensor and the measured value is input to the controller, and infrared light emitted from the temperature measurement solder is received by the radiation thermometer, the temperature of the temperature measurement solder is measured by the radiation thermometer and the measured value is input to the controller, the controller calculates an emissivity offset amount corresponding to the difference between the measured value by the temperature sensor and the measured value by the radiation thermometer, and offsets the emissivity of the radiation thermometer based on the calculated emissivity offset amount.

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