Controller, program, bonding system, and bonding method

Abstract

The temperature of the workpiece during induction heating for soldering is kept within a desired temperature range. [Solution] The detection unit 92A of the controller 90 periodically detects the temperature of the workpiece W as a detected temperature Te using the camera 50 (temperature sensor). The processing unit 92B executes a control process that controls the coil current I based on the detected temperature Te periodically detected by the detection unit 92A. The control process is performed when the detected temperature Te is a predetermined first upper limit value (specifically, upper limit value T1 Hi or upper limit T2 Hi A first process that reduces the coil current I when the temperature rises to a predetermined first lower limit (specifically, the lower limit T1 Lo or lower limit T2 Lo This includes a second process of increasing the coil current I when it drops down to ).

Description

[Technical Field]

[0001] The present invention relates to a controller, a program, a bonding system, and a bonding method. [Background technology]

[0002] As disclosed in Patent Document 1, a technique is known in which a workpiece including a first component, a second component, and solder is heated by induction heating using a coil, and then soldered. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-59164 [Overview of the project] [Problems that the invention aims to solve]

[0004] In Patent Document 1, induction heating is stopped only when the workpiece temperature exceeds the overheat protection threshold, and it is not possible to keep the workpiece temperature within a desired temperature range during induction heating. If the workpiece temperature can be kept within a desired temperature range, for example, the probability of induction heating being stopped as described in Patent Document 1 will be reduced. In addition, the probability of workpiece abnormalities caused by heat during induction heating will also be reduced.

[0005] The present invention aims to maintain the temperature of a workpiece within a desired temperature range during induction heating for soldering. [Means for solving the problem]

[0006] In order to solve the above problem, a controller according to the present invention is a controller for controlling a coil current that causes induction heating to flow through a coil when heating a workpiece including a first component, a second component and solder by induction heating using the coil and soldering the first component and the second component with the solder, the controller comprising: a detection unit that periodically detects a temperature of the workpiece as a detected temperature by a temperature sensor; and a processing unit that executes a control process for controlling the coil current based on the detected temperature periodically detected by the detection unit, wherein the control process includes a first process of decreasing the coil current when the detected temperature rises to a predetermined first upper limit value, and a second process of increasing the coil current when the detected temperature falls to a predetermined first lower limit value.

[0007] A program according to the present invention causes a computer to function as the above controller.

[0008] A bonding system according to the present invention includes the controller, the coil, and the temperature sensor.

[0009] A bonding method according to the present invention is a bonding method for soldering a first component and a second component with solder by heating a workpiece including the first component, the second component and the solder through induction heating using a coil, the method comprising: a detection step of periodically detecting, by a temperature sensor, the temperature of the workpiece during heating by induction heating as a detected temperature; and a control step of controlling a coil current that causes the induction heating to flow through the coil based on the detected temperature periodically detected in the detection step, wherein the control step includes a first step of decreasing the coil current when the detected temperature rises to a predetermined first upper limit value, and a second step of increasing the coil current when the detected temperature falls to a predetermined first lower limit value. Effects of the Invention

[0010] According to the present invention, the temperature of the workpiece during induction heating for soldering can be maintained within a desired temperature range. [[Brief Description of Drawings]]

[0011] [Figure 1] Figure 1 is a schematic diagram showing the configuration of a bonding system according to an embodiment of the present invention. [Figure 2] Figure 2 is a block diagram showing the main configuration of a controller. [Figure 3] Figure 3 is a flowchart of a heating process. [Figure 4] Figure 4(A) is a graph showing the temporal change of detected temperature in the heating process. Figure 4(B) is a graph showing the temporal change of coil current. [Figure 5] Figure 5(A) is a graph showing the temporal change of detected temperature in another example of the heating process. Figure 5(B) is a graph showing the temporal change of coil current in another example of the heating process. [[Mode for Carrying Out the Invention]]

[0012] Hereinafter, a bonding system 10, a bonding method and the like according to an embodiment of the present invention will be described with reference to the drawings. Note that soldering described in the present specification is a concept that includes brazing. That is, solder includes brazing filler metal.

[0013] The bonding system 10 according to the present embodiment shown in Figure 1 heats a workpiece W including a component W1, a component W2, and solder S interposed therebetween by induction heating, melts the solder S, and solders (bonds) the components W1 and W2. The components W1 and W2 may be any arbitrary components. The components W1 and W2 may be any one of thermoplastic FPC (Flexible Printed Circuits) such as PET, liquid crystal polymer, and fluorine-based materials, LED elements, micro LED (OLED) elements, 3D-MID (Molded Interconnect Device), and the like. The solder S may be configured as a plurality of bumps that respectively bond a plurality of terminals of the component W1 and a plurality of terminals of the component W2.

[0014] The bonding system 10 comprises a stage 20, a coil 30, a power supply circuit 40, a camera 50, a moving mechanism 60, an input / output device 70, and a controller 90.

[0015] Stage 20 supports the workpieces W. Stage 20 may be configured as a belt conveyor that sequentially transports multiple workpieces W under the coil 30.

[0016] The coil 30 heats the workpiece W by electromagnetic induction, melting the solder S and soldering components W1 and W2 with the solder S. The coil 30 is supported by a support member (not shown). The method of heating the workpiece W by electromagnetic induction using the coil 30 may be either directly heating the solder S by induction heating, or heating component W1 or W2 by induction heating and then heating the solder S as a result.

[0017] The power supply circuit 40 generates induction heating to heat the workpiece W by passing a high-frequency alternating current through the coil 30 under the control of the controller 90. The alternating current flowing through the coil 30 is also called the coil current. The power supply circuit 40 is composed of a plurality of switching elements that generate the coil current, and the controller 90 controls the coil current (particularly the amplitude and / or frequency) by controlling the switching of the plurality of switching elements.

[0018] Camera 50 has the function of a temperature sensor and the function of a normal camera. Camera 50 is positioned above the workpiece W and coil 30 and, under the control of controller 90, images the workpiece W from above through the central cavity of coil 30. The temperature sensor here is a non-contact temperature sensor, and in this case, it is a radiation thermometer in particular. The temperature sensor may also be, for example, another non-contact temperature sensor such as a thermograph. As a non-contact temperature sensor, camera 50 captures a thermal image of the workpiece W by capturing the infrared radiation emitted by the workpiece W. As a normal camera (e.g., a visible light camera or an ultraviolet camera), camera 50 captures an image (visible image or ultraviolet image) of the workpiece W by capturing the visible light or ultraviolet light reflected by the workpiece W. Camera 50 supplies each captured image to controller 90. Controller 90 detects the temperature of the workpiece W by acquiring the thermal image from camera 50. The detected temperature is also called the detected temperature. Controller 90 detects the state of the workpiece W by acquiring the image (visible image, etc.) from camera 50.

[0019] The moving mechanism 60 consists of, for example, a 3-axis robot, and under the control of the controller 90, moves the coil 30 and camera 50 together relative to the stage 20 and the workpiece W. The moving mechanism 60 achieves the above relative movement by moving the coil 30 and at least one of the stage 20 and the workpiece W. By moving the coil 30 and camera 50 together relative to each other, the focal position of the camera 50 can be kept at a constant distance from the coil 30.

[0020] The input / output device 70 includes a display device, an input device, etc., and is connected to the controller 90. The input / output device 70 displays various images and accepts various operations from the user (for example, editing the heat treatment conditions described below, inputting learning data, etc.).

[0021] The controller 90 consists of various computers and controls the operation of the junction system 10 (particularly the coil current). The controller 90 includes a non-volatile storage 91 for storing programs and other data, and a processor 92 for executing the programs stored in the storage 91. The storage 91 also stores data used in the following processes, such as heating conditions, learning data sets, and inspection models. Details of the heating conditions and learning data sets will be described later. The processor 92 is composed of one or more CPUs (Central Processing Units), etc. The controller 90 further includes a main memory 93 that provides a workspace for the processor 92, and an I / O (Input / Output) 94 that relays electrical signals transmitted and received between the processor 92 and the outside of the controller 90. The I / O 94 may include a circuit that amplifies electrical signals from the outside (camera 50, input / output device 70, etc.) and converts them from analog to digital. Furthermore, I / O94 may include a circuit that converts control signals from processor92 from digital to analog and supplies them to the controlled object (power supply circuit 40, moving mechanism 60, input / output device 70, etc.).

[0022] The processor 92 operates as the detection unit 92A, processing unit 92B, and machine learning unit 92C, as shown in Figure 2, by executing the program stored in the storage 91.

[0023] The detection unit 92A periodically detects the temperature of the workpiece W as the detected temperature Te using the camera 50 (temperature sensor). The detection period of the periodic detection of the detected temperature Te by the detection unit 92A may be constant or it may vary.

[0024] The processing unit 92B executes a control process to control the coil current (hereinafter also referred to as coil current I) based on the detected temperature Te periodically detected by the detection unit 92A.

[0025] The detection unit 92A and the processing unit 92B work together to perform the heat treatment shown in Figure 3. The following parameters used in this treatment are included in the heat treatment conditions stored in the storage 91 and are used. The above parameters include the upper limit value T1 Hi And the lower limit T1 Lo And the target value T1c and the upper limit value T2 Hi And the lower limit T2 Lo This includes a target value T2c, currents I1 to I7, control parameters for controlling the power supply circuit 40 and the moving mechanism 60, a first heating period P1, and a second heating period P2.

[0026] In the heating process, first, the processing unit 92B controls the moving mechanism 60 to move the coil 30 and camera 50 to predetermined positions (step S11). These predetermined positions are positions where the workpiece W can be inductively heated by the coil 30 (for example, the position in Figure 1).

[0027] Subsequently, the processing unit 92B controls the power supply circuit 40 and starts supplying coil current I to the coil 30 (step S12). In step S12, current I1 is supplied first. This initiates induction heating of the workpiece W, and the solder S is heated.

[0028] Subsequently, the detection unit 92A detects the temperature of the workpiece W as the detected temperature Te using the camera 50 (temperature sensor) (step S13). The detection unit 92A detects the detected temperature Te based on the thermal image captured by the camera 50. The detected temperature Te can be, for example, the temperature of any region or position in the thermal image from the camera 50. Here, the detected temperature Te is the temperature in a predetermined annular region within the thermal image. The annular region is pre-set as the region in the thermal image where the annular portion of the solder S that extends beyond the component W1 is captured when the workpiece W is viewed from above by the camera 50. As a result, the temperature of the solder S is detected as the detected temperature Te of the workpiece W. Note that if the temperature shown in the thermal image differs depending on the position of the annular region, i.e., the annular portion of the solder S, the detected temperature Te may be any temperature such as the average temperature, minimum temperature, or maximum temperature.

[0029] After step S13, the processing unit 92B controls the coil current I based on the detected temperature Te detected by the detection unit 92A (step S14).

[0030] Thereafter, the processing unit 92B determines whether the end timing of the current heating processing has arrived (step S15). Until this end timing arrives (step S15; No), the processing of steps S13 to S14 is repeatedly performed.

[0031] The processing unit 92B performs the above control processing in repeatedly executed step S14. The detected temperature Te and the coil current I under this control processing change as shown in FIGS. 4(A) and 4(B). The processing unit 92B executes the above control processing to realize a temperature profile (two-stage heating) in which, as shown in FIG. 4, heating with the temperature of a workpiece W (solder S) set to a target value T1c is performed only for a first heating period P1, and then heating with the temperature of the workpiece W (solder S) set to a target value T2c is performed only for a second heating period P2.

[0032] The target value T1c shown in FIG. 4(A) is preset as a desired temperature of the workpiece W in the heating of the first heating period P1, that is, a target temperature. An upper limit value T1 Hi and a lower limit value T1 Lo are respectively preset as an allowable upper limit temperature and an allowable lower limit temperature when the target value T1c is used as the target temperature. The target value T2c is preset as a suitable temperature of the workpiece W (solder S herein) during heating in the second stage, that is, a target temperature. An upper limit value T2 Hi and a lower limit value T2 Lo are respectively preset as an allowable upper limit temperature and an allowable lower limit temperature when the target value T2c is used as the target temperature. The target value T1c is the upper limit value T1 Hi and the lower limit value T1 Lo may be an intermediate value (for example, an average value) of , or may be any other value between the upper limit value T1 Hi and the lower limit value T1 Lo The target value T2c is the upper limit value T2 Hi and the lower limit value T2 Lo may be an intermediate value (for example, an average value) of , or may be any other value between the upper limit value T2 Hi and the lower limit value T2Lo Any other value between those two is also acceptable.

[0033] In Figure 4(B), the coil current I is the effective value of the alternating current flowing through the coil 30. The processing unit 92B controls the coil current I to one of the currents I1 to I7, as described later. The processing unit 92B realizes the currents I1 to I7 by controlling the power supply circuit 40 according to the control pattern corresponding to each of the currents I1 to I7. As another example, the processing unit 92B may use the value of the coil current I detected by an ammeter (not shown) (which may be the integral value of the coil current I during the sampling period, etc.) as a feedback value, and use the coil current I as a target value indicating one of the target currents I1 to I7, thereby realizing the currents I1 to I7.

[0034] In the above control process, the processing unit 92B first maintains the coil current I at current I1 until the detected temperature Te reaches the target value T1c (timing t1~t3). In particular, the processing unit 92B maintains the coil current I at current I1 until the detected temperature Te reaches the lower limit value T1c. Lo From the point where the temperature rises to the target value T1c, the coil current I is controlled to current I1, thereby increasing the temperature of the workpiece W (solder S) (which can also be called the detected temperature Te) (timing t2~t3).

[0035] When the detected temperature Te rises to the target value T1c, the processing unit 92B controls the coil current I to a current I2 (I1>I2>I4) which is smaller than current I1 (timing t3~t4). As a result, the temperature of the workpiece W (solder S) (detected temperature Te) continues to rise, but the rate of increase is lower than at timings t2~t3.

[0036] The processing unit 92B determines that the detected temperature Te is above the upper limit T1 HiWhen the temperature rises to a certain point, the coil current I is controlled to a current I3 (I4 > I3) which is smaller than current I2 (timing t4~t5). As a result, the temperature of the workpiece W (solder S) (detected temperature Te) begins to decrease. Note that current I3 may be 0. In other words, the supply of coil current I may be stopped during timing t4~t5. Current I3 may be greater than 0. In other words, the supply of coil current I may be continued.

[0037] When the detected temperature Te drops to the target value T1c, the processing unit 92B controls the coil current I to a current I4 (I2>I4>I3) which is greater than the current I3 (timing t5~t6). As a result, the temperature of the workpiece W (solder S) (detected temperature Te) continues to decrease, but the rate of decrease is slower than when timing t4~t5.

[0038] The processing unit 92B determines that the detected temperature Te is lower than the lower limit T1 Lo When it has decreased to this point (timing t6), the coil current I is increased to current I1, and the processing from timings t2 to t3 onwards is restarted.

[0039] From this point onward, the processes at timings t2 to t6 are repeatedly performed until the end of the first heating period P1.

[0040] The processing unit 92B determines that the detected temperature Te is lower than the lower limit T1 Lo The elapsed time from the first time the temperature was reached (timing t2) is measured, and when the elapsed time reaches the first heating period P1 (timing t7), the coil current I is increased to current I5 in order to transition to the second heating period P2.

[0041] Subsequently, the processing unit 92B maintains the coil current I at current I5 until the detected temperature Te reaches the target value T2c (timing t7~t9). In particular, the processing unit 92B maintains the coil current I at current I5 until the detected temperature Te reaches the lower limit T2c. Lo From the point where the temperature rises to the target value T2c, the coil current I is controlled to current I5, thereby increasing the temperature of the workpiece W (solder S) (which can also be called the detected temperature Te) (timing t8~t9).

[0042] When the detected temperature Te rises to the target value T2c, the processing unit 92B controls the coil current I to a current I6 (I5 > I6 > I7) which is smaller than the current I5 (timing t9~t10). As a result, the temperature of the workpiece W (solder S) (detected temperature Te) continues to rise, but the rate of increase is lower than when timing t8~t9 occurs.

[0043] The processing unit 92B determines that the detected temperature Te is above the upper limit T1 Hi When the temperature rises to a certain point, the coil current I is controlled to a current I3 (I4 > I3) which is smaller than current I6 (timing t10~t11). As a result, the temperature of the workpiece W (solder S) (detected temperature Te) begins to decrease. Note that the current I3 at timings t10~t11 is the same as the current I3 at timings t4~t5, but the two currents may be different. Current I3 only needs to be smaller than current I7, which will be described later.

[0044] When the detected temperature Te drops to the target value T2c, the processing unit 92B controls the coil current I to a current I7 (I6>I7>I1) which is greater than current I3 (timing t11~t12). As a result, the temperature of the workpiece W (solder S) (detected temperature Te) continues to decrease, but the rate of decrease is lower than when timing t10~t11. Current I7 may be lower than current I1 and / or I2.

[0045] The processing unit 92B determines when the detected temperature Te is below the lower limit T2 Lo When it has decreased to this point (timing t12), the coil current I is increased to current I5, and the processing from timings t8 to t9 onwards is restarted.

[0046] From this point onward, the processing at timings t8 to t12 is repeated until the end of the second heating period P2.

[0047] The processing unit 92B determines when the detected temperature Te is below the lower limit T2 LoThe elapsed time from the first time the condition was reached (timing t2) is measured. When the elapsed time reaches the second heating period P2 (timing t13), the processing unit 92B determines in step S15 of Figure 3 that the timing for the end of the current heating treatment has arrived (step S15; Yes). At this time, the heating treatment ends.

[0048] The processing unit 92B in Figure 2 may, in parallel with the control processing described above, capture an image of the workpiece W using the camera 50, monitor the captured image (visible image or ultraviolet image), and inspect the presence or absence of abnormalities in the workpiece W captured in the image using a predetermined inspection model. The inspection model (more specifically, the model parameters that characterize the model) is stored in the storage 91. Examples of abnormalities in the workpiece W include melting of component W1 or W2, deformation of component W1 or W2, deterioration of component W1 or W2, shape defects of solder S, and the appearance of signs thereof. If the processing unit 92B detects any of the abnormalities, it may discontinue the control processing described above. The camera for image inspection may be separated from the camera 50 and positioned to capture the workpiece W from the side so as to capture the solder S.

[0049] The machine learning unit 92C may construct the inspection model by performing machine learning with correct answers based on an image of the workpiece W in which an abnormality (e.g., a faulty solder joint) has occurred due to the heat treatment (especially the control treatment described above) and an image of the workpiece W in which the heat treatment has been completed normally and no abnormality has occurred. The image used in the machine learning may be an image of the workpiece W after the heat treatment captured by the camera 50.

[0050] The processing unit 92B may store the heating conditions and the processing results of the heating under those conditions (presence or absence of abnormalities in the workpiece W, particularly the solder S) as training data in the storage unit 91. This collection of training data is stored in the storage unit 91 as a training data group. In order to obtain diverse training data, the processing unit 92B may slightly change the heating conditions (upper limit, lower limit, target value, heating period, etc.) in each of the multiple heating processes (multiple control processes). The processing unit 92B may consider the processing result to be abnormal when the control process is stopped as described above, and to be normal when the process is not stopped. The machine learning unit 92C performs machine learning based on this training data group to determine the heating conditions (especially the upper limit T1 Hi Target value T1c, lower limit T1 Lo Upper limit T2 Hi Target value T2c, lower limit T2 Lo ) Update.

[0051] As described above, the controller 90 according to this embodiment is configured to control the coil current I that flows through the coil 30 to generate the induction heating when a workpiece W including component W1, component W2, and solder S is heated by induction heating using the coil 30 to solder component W1 and component W2 with solder S. Furthermore, the detection unit 92A of the controller 90 periodically detects the temperature of the workpiece W as a detected temperature Te using the camera 50 (temperature sensor). The processing unit 92B executes a control process to control the coil current I based on the detected temperature Te periodically detected by the detection unit 92A. The control process is performed when the detected temperature Te is a predetermined first upper limit value (specifically, upper limit value T1 Hi or upper limit T2 Hi A first process that reduces the coil current I when the temperature rises to a predetermined first lower limit (specifically, the lower limit T1 Lo or lower limit T2 Lo This includes a second process of increasing the coil current I when it drops down to ).

[0052] With the above configuration, the temperature of the workpiece W can be controlled between a first upper limit and a first lower limit during the first and second processes. Therefore, the temperature of the workpiece W can be controlled within a desired temperature range. This also reduces the probability of abnormalities occurring in the workpiece W due to heat during induction heating. Furthermore, even if at least one of the components W1 and W2 is a low heat-resistant component, high-quality soldering can be performed without contact, suppressing thermal damage.

[0053] Furthermore, as described above, the processing unit 92B states that the above control processing includes the following (1) to (5). (1) When the detected temperature Te is lower limit T1 Lo (or T2 Lo The first control process (timing t2~t3 (or t8~t9)) raises the temperature of the workpiece W (solder) (detected temperature Te) by controlling the coil current I to current I1 (or I5) until it rises from ) to the target value T1c (or T2c). (2) When the detected temperature Te rises to the target value T1c (or T2c), a second control process (timing t3~t4 (or t9~t10)) is performed to raise the temperature of the workpiece W (solder) (detected temperature Te) at a slower rate than in the first control process by controlling the coil current I to a current I2 (or I6) that is smaller than the current I1 (or I5). (3) When the detected temperature Te is above the upper limit T1 Hi (or T2 Hi A third control process (timing t4~t5 (or t10~t11)) is performed to lower the temperature of the workpiece W (solder) (detected temperature Te) by controlling the coil current I to a current I3 that is smaller than current I2 (or any current lower than current I7) when the temperature rises to ). (4) A fourth control process (timing t5~t6 (or t11~t12)) is performed to lower the temperature of the workpiece W (solder) (detected temperature Te) at a slower rate than in the third control process by controlling the coil current I to a current I4 (or I7) that is greater than current I3 (or any current lower than current I7) when the detected temperature Te has fallen to the target value T1c (or T2c). (5) When the detected temperature Te is lower limit T1 Lo (or T2Lo When the current drops to ), the fifth control process (timing t6 or t12) increases the coil current I to current I1 (or I5) and starts the first control process.

[0054] Through the control process described above, the coil current I is varied starting from the target value T1c or T2c, thereby achieving stable temperature control of the workpiece W while suppressing overshoot and undershoot of the detected temperature Te during each of the heating periods P1 and P2. In other words, the temperature of the workpiece W can be kept within the desired temperature range. As the control process described above, instead of the first to fifth control processes, binary control using currents I11 and I12 (or I12 and I13) as shown in Figure 5 may be used for each of the heating periods P1 and P2, but the first to fifth control processes enable more accurate temperature control than the binary control. Furthermore, the first to fifth control processes and binary control do not require complex control algorithms such as PID control. It should also be noted that the first to fifth control processes may be executed during one of the first heating period P1 and the second heating period P2, while binary control may be executed during the other. Furthermore, when binary control is performed during both the first heating period P1 and the second heating period P2, the lower currents for both binary controls may be a common current I13 as shown in Figure 5, or they may be different.

[0055] As described above, the control process is performed when the detected temperature Te is set to a predetermined first upper limit (upper limit T1 Hi A first process that reduces the coil current I when the temperature rises to a predetermined first lower limit (lower limit T1 Lo The control process includes a second process of increasing the coil current I when the temperature drops to a predetermined second upper limit (upper limit T2) which is different from the first upper limit. Hi A third process that reduces the coil current I when it rises to ) and a third process that changes the detected temperature Te to a predetermined second lower limit (lower limit T2) which is different from the first lower limit. LoThe system may further include a fourth process of increasing the coil current I when the temperature drops to a certain level. The first and second processes are performed during a first heating period P1, and the third and fourth processes are performed during a second heating period P2 following the first heating period P1. With this configuration, even if the first heating period P1 and the second heating period P2 have different heating temperatures, the temperature of the workpiece W can be kept within a desired temperature range during each of these periods.

[0056] As described above, the current I3 or I12 may be 0. This creates a period during which induction heating does not occur, further suppressing the rise in temperature of the workpiece W.

[0057] Furthermore, as described above, the processing unit 92B may acquire an image of the workpiece W (especially the solder S) during the heating process, and may stop the heating process when it detects an abnormality in the workpiece W (especially the solder S) based on the acquired image. This prevents the heating process from continuing in the event of an abnormality.

[0058] Furthermore, in the above control process, the processing unit 92B determines the upper limit (T1) based on the detected temperature Te. Hi (etc.) and lower limit (T1 Lo The above control process is executed according to the heat treatment conditions, including (etc.). The machine learning unit 92C may update the heat treatment conditions by machine learning based on the heat treatment conditions when the workpiece W after soldering is normal and a good product, and the heat treatment conditions when the workpiece W after soldering is abnormal and a defective product. This improves the heat treatment conditions and makes the temperature control of the workpiece W more suitable.

[0059] Furthermore, as shown in Figure 1, the camera 50, acting as a non-contact temperature sensor (particularly a radiation thermometer), faces the workpiece W through the central cavity of the coil 30 and captures a thermal image of the workpiece W. This reduces blind spots in the thermal image captured by the temperature sensor of the workpiece W compared to, for example, when the temperature sensor is placed diagonally above the workpiece W. Specifically, as shown in Figure 1, when the workpiece W is viewed from the side (above) of the coil 30, if the edge of the solder S appears as an annular portion around the component W1, and the temperature sensor is placed diagonally above the workpiece W, the end of the edge of the solder S on the opposite side of the temperature sensor will be hidden by the component W1. However, the above structure reduces such blind spots. As a result, a thermal image showing the entire annular portion of the solder S is obtained, and the detection unit 92A can appropriately detect the temperature (particularly the temperature distribution) of the entire annular portion of the solder S based on this thermal image, thereby obtaining an appropriate detected temperature Te. The non-contact temperature sensor may be provided separately from the camera 50 and face the workpiece W via a cavity in the center of the coil 30.

[0060] The number of heating periods is not limited to two, such as the first heating period P1 and the second heating period P2; it can be one or more. The relative values ​​of the workpiece temperature (target value, upper limit, lower limit) during multiple heating periods are also arbitrary, and the temperature may be high initially and then decrease.

[0061] (modified version) Various modifications are possible to the above embodiment. For example, the various configurations described in the above embodiment are arbitrary and can be changed as appropriate. For example, the processor 92 may consist of at least one or more combinations of one or more CPUs, one or more ASICs (Application Specific Integrated Circuits), and one or more FPGAs (Field-Programmable Gate Arrays). The processor 92 can also be called a processing unit. The program may be stored in a non-temporary storage medium that can be read by a computer, such as a non-volatile storage 91. The coil 30 should be formed in a structure suitable for heating the workpiece W by induction heating (a structure capable of heating the workpiece W). The shape of the workpiece W is also arbitrary.

[0062] (Note) Configurations based on the above embodiments and modifications are provided as examples. The provided configurations are interchangeable. (Note 1) A controller for controlling the coil current that flows through a coil to generate induction heating when a workpiece including a first component, a second component, and solder is heated by induction heating using a coil to solder the first component and the second component together with the solder, A detection unit periodically detects the temperature of the workpiece as the detected temperature using a temperature sensor, The system includes a processing unit that performs a control process to control the coil current based on the detected temperature periodically detected by the detection unit, The control process includes a first process of reducing the coil current when the detected temperature rises to a predetermined first upper limit, and a second process of increasing the coil current when the detected temperature falls to a predetermined first lower limit. controller. (Note 2) A target value is set between the first upper limit and the first lower limit. The aforementioned control process is A first control process to raise the temperature of the solder by controlling the coil current to a first current while the detected temperature rises from the first lower limit to the target value, When the detected temperature rises to the target value, a second control process is performed in which the coil current is controlled to a second power that is smaller than the first current, thereby increasing the temperature of the solder at a slower rate than during the first control process. When the detected temperature rises to the first upper limit, a third control process is performed to lower the temperature of the solder by controlling the coil current to a third current smaller than the second current, When the detected temperature drops to the target value, a fourth control process is performed to control the coil current to a fourth current that is larger than the third current, thereby lowering the temperature of the solder at a slower rate than during the third control process. A fifth control process is included, in which, when the detected temperature falls to the lower limit, the coil current is increased to the first current and the first control process is started. The controller described in Appendix 1. (Note 3) The control process further includes a third process of reducing the coil current when the detected temperature rises to a predetermined second upper limit different from the first upper limit, and a fourth process of increasing the coil current when the detected temperature falls to a predetermined second lower limit different from the first lower limit. The first process and the second process are executed in the first period. The third and fourth processes are executed in the second period following the first period. The controller described in Appendix 1 or 2. (Note 4) The control process reduces the coil current to 0 in both the first process and the second process. The controller described in Appendix 3. (Note 5) The processing unit acquires an image of the workpiece taken during the control process, and when it detects an abnormality in the workpiece based on the acquired image, it stops the control process. The controller described in any of the appendices 1-4. (Note 6) With an additional machine learning department, The processing unit executes the control process based on the detected temperature and in accordance with the heating conditions including the upper and lower limits. The machine learning unit updates the heat treatment conditions by machine learning based on the heat treatment conditions when the workpiece W after soldering is a good product and the heat treatment conditions when the workpiece W after soldering is a defective product. The controller described in any of the appendices 1-5. (Note 7) A program that causes a computer to function as a controller as described in one of the appendices 1 to 6. (Note 8) A controller as described in any of the appendices 1 to 6, The aforementioned coil, The temperature sensor and, A joining system equipped with the following features. (Note 9) The temperature sensor is a non-contact type temperature sensor that faces the workpiece through a cavity in the center of the coil and captures a thermal image of the workpiece. The joining system described in Appendix 8. (Note 10) A joining method comprising heating a workpiece including a first component, a second component, and solder by induction heating using a coil, thereby soldering the first component and the second component together with the solder, A detection step in which the temperature of the workpiece during heating by induction heating is periodically detected as the detected temperature by a temperature sensor, The system includes a control step that controls the coil current that flows through the coil to produce the induction heating, based on the detected temperature periodically detected by the detection step, The control step includes a first step of decreasing the coil current when the detected temperature rises to a predetermined first upper limit, and a second step of increasing the coil current when the detected temperature falls to a predetermined first lower limit. Joining method. (Note 11) A target value is set between the first upper limit and the first lower limit. The control step described above is: A first control step involves controlling the coil current to a first current to raise the temperature of the solder while the detected temperature rises from the first lower limit to the target value, When the detected temperature rises to the target value, a second control step is performed in which the coil current is controlled to a second power that is smaller than the first current, thereby increasing the temperature of the solder at a slower rate than in the first control step. A third control step is performed to lower the temperature of the solder by controlling the coil current to a third current smaller than the second current when the detected temperature rises to the first upper limit, A fourth control step is performed in which, when the detected temperature drops to the target value, the coil current is controlled to a fourth current that is larger than the third current, thereby lowering the temperature of the solder at a slower rate than in the third control step. A fifth control step includes, when the detected temperature drops to the lower limit, increasing the coil current to the first current and starting the first control step, The joining method described in Appendix 10. (Note 12) The control step further includes a third step of reducing the coil current when the detected temperature rises to a predetermined second upper limit different from the first upper limit, and a fourth step of increasing the coil current when the detected temperature falls to a predetermined second lower limit different from the first lower limit. The first and second steps are performed in the first period. The third and fourth steps are performed in the second period following the first period. The joining method described in Appendix 10 or 11. (Note 13) The processing step includes acquiring an image of the workpiece taken during the control process, and stopping the control process when an abnormality of the workpiece is detected based on the acquired image. The joining method described in any of the appendices 10 to 12. (Note 14) With further machine learning steps, The processing step is performed based on the detected temperature and in accordance with heating conditions including the upper and lower limits. The machine learning step updates the heat treatment conditions by machine learning based on the heat treatment conditions when the workpiece W after soldering is a good product and the heat treatment conditions when the workpiece W after soldering is a defective product. The joining method described in any of the appendices 10 to 13.

[0063] (Scope of the present invention) The present invention has been described above with reference to embodiments and modifications, but the present invention is not limited to the above embodiments and modifications. For example, the present invention includes various modifications to the above embodiments and modifications that can be understood by those skilled in the art within the scope of the technical concept of the present invention. Each of the components listed in the above embodiments and modifications can be combined as appropriate to the extent that they do not contradict each other. Furthermore, each component can be omitted at will. [Explanation of symbols]

[0064] 10...Joining system, 20...Stage, 30...Coil, 40...Power supply circuit, 50...Camera, 60...Movement mechanism, 70...Input / output device, 90...Controller, 91...Storage, 92...Processor, 92A...Detection unit, 92B...Processing unit, 92C...Machine learning unit, 93...Main memory, S...Solder, W...Workpiece, W1...Component, W2...Component.

Claims

1. A controller for controlling the coil current that flows through a coil to generate induction heating when a workpiece including a first component, a second component, and solder is heated by induction heating using a coil to solder the first component and the second component together with the solder, A detection unit periodically detects the temperature of the workpiece as the detected temperature using a temperature sensor, The system includes a processing unit that performs a control process to control the coil current based on the detected temperature periodically detected by the detection unit, The control process includes a first process of reducing the coil current when the detected temperature rises to a predetermined first upper limit, and a second process of increasing the coil current when the detected temperature falls to a predetermined first lower limit. controller.

2. A target value is set between the first upper limit and the first lower limit. The aforementioned control process is: A first control process is performed to raise the temperature of the solder by controlling the coil current to a first current while the detected temperature rises from the first lower limit to the target value, When the detected temperature rises to the target value, a second control process is performed in which the coil current is controlled to a second power smaller than the first current, thereby increasing the temperature of the solder at a slower rate than during the first control process. When the detected temperature rises to the first upper limit, a third control process is performed to lower the temperature of the solder by controlling the coil current to a third current that is smaller than the second current, When the detected temperature drops to the target value, a fourth control process is performed to control the coil current to a fourth current that is larger than the third current, thereby lowering the temperature of the solder at a slower rate than during the third control process. A fifth control process is included, in which, when the detected temperature falls to the lower limit, the coil current is increased to the first current and the first control process is started. The controller according to claim 1.

3. The control process further includes a third process of reducing the coil current when the detected temperature rises to a predetermined second upper limit value different from the first upper limit value, and a fourth process of increasing the coil current when the detected temperature falls to a predetermined second lower limit value different from the first lower limit value. The first process and the second process are executed in the first period. The third and fourth processes are performed in the second period following the first period. The controller according to claim 1.

4. The control process reduces the coil current to zero in both the first and second processes. The controller according to claim 3.

5. The processing unit acquires an image of the workpiece taken during the control process, and when it detects an abnormality in the workpiece based on the acquired image, it stops the control process. The controller according to claim 1.

6. With an additional machine learning unit, The processing unit executes the control process based on the detected temperature and in accordance with the heating conditions including the upper and lower limits. The machine learning unit updates the heat treatment conditions by machine learning based on the heat treatment conditions when the workpiece W after soldering is a good product and the heat treatment conditions when the workpiece W after soldering is a defective product. The controller according to claim 1.

7. A program that causes a computer to function as the controller described in claim 1.

8. The controller according to claim 1, The aforementioned coil, The temperature sensor and, A joining system equipped with the following features.

9. The temperature sensor is a non-contact type temperature sensor that faces the workpiece through a cavity in the center of the coil and captures a thermal image of the workpiece. The joining system according to claim 8.

10. A joining method comprising heating a workpiece including a first component, a second component, and solder by induction heating using a coil, thereby soldering the first component and the second component together with the solder, A detection step in which the temperature of the workpiece during heating by induction heating is periodically detected as the detected temperature by a temperature sensor, The system includes a control step that controls the coil current that flows through the coil to produce the induction heating, based on the detected temperature periodically detected by the detection step, The control step includes a first step of decreasing the coil current when the detected temperature rises to a predetermined first upper limit, and a second step of increasing the coil current when the detected temperature falls to a predetermined first lower limit. Joining method.

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