JP4949128B2 - Solder melting equipment - Google Patents

Description

 The present invention relates to a solder melting apparatus that melts solder by heating a predetermined heating target portion to a normal set temperature with a heater.

For example, Japanese Patent No. 3670072 discloses a normal operation mode in which solder is melted by heating a tip (heating target portion) to a normal set temperature with a heater, and when the use of the tip is interrupted. A soldering iron device having a sleep mode that lowers the tip to a sleep set temperature is disclosed. According to such a soldering iron device, it is possible to reduce power consumption when the tip is not used, and to prevent the tip from being oxidized, thereby extending its life.
Japanese Patent No. 3670072

 By the way, in the soldering operation, if the soldering time (the time for applying the tip to the soldering object) is too long, the soldering object is damaged due to thermal damage. Conventionally, such a soldering time is left to the judgment of a soldering worker, and an appropriate judgment cannot be made by a skilled worker. Also, even if a manual for soldering time is created so that the soldering work can be performed uniformly regardless of the skill level of the worker, the manual is inadvertently inadvertent as long as the work is done manually. There is a possibility that the prescribed soldering time will be exceeded and the soldering object will be destroyed.

 The present invention has been made in view of the above-described circumstances, and an object of the present invention is to prevent destruction of an object to be soldered in a soldering operation regardless of the skill level or carelessness of the operator.

In order to achieve the above object, in the present invention, as a first solution means for a solder melting apparatus,
A solder melting apparatus that melts solder by heating a predetermined heating target portion to a normal set temperature by a heater, the temperature detecting means for detecting the temperature of the heating target portion, and the temperature of the heating target portion is the normal temperature And a notification control means for notifying the outside that a predetermined soldering time has elapsed from the soldering start time when a predetermined temperature drop from the set temperature is set as the soldering start time. .

  Further, in the present invention, as a second solving means relating to the solder melting apparatus, in the first solving means, the notification control means starts counting the soldering time from the soldering start time, and the solder It has control means for outputting an alarm generation signal when an attachment time has elapsed, and notification means for generating an alarm outward in response to the alarm generation signal.

 Further, in the present invention, as a third solving means relating to the solder melting apparatus, in the second solving means, the control means is configured to apply the heating object before the soldering time elapses from the soldering start time. When the temperature of the part returns to the normal set temperature, the time measurement of the soldering time is terminated.

 Further, in the present invention, as a fourth solving means relating to the solder melting apparatus, in the second or third solving means, the control means is configured such that the temperature of the heating target portion is the temperature after the soldering time has elapsed. The output of the alarm generation signal is continued until the temperature returns to the normal set temperature.

 Further, in the present invention, as a fifth solving means relating to the solder melting apparatus, in the first solving means, the notification control means starts measuring the soldering time from the soldering start time and generates an alarm. A control means for outputting a signal and stopping the output of the alarm generation signal when the soldering time has elapsed, and an informing means for generating an alarm outward in response to the alarm generation signal. Features.

 Further, in the present invention, as a sixth solving means relating to the solder melting apparatus, in the fifth solving means, the control means is configured to apply the heating object before the soldering time elapses from the soldering start time. When the temperature of the part returns to the normal set temperature, the time measurement of the soldering time is terminated and the output of the alarm generation signal is stopped.

 Further, in the present invention, as a seventh solving means relating to the solder melting apparatus, in any one of the second to sixth solving means, the control means, after the elapse of the soldering time, When a predetermined time elapses without the temperature returning to the normal set temperature, heating of the heating target portion by the heater is stopped.

  According to the solder melting apparatus according to the present invention, by notifying the outside that a predetermined soldering time has elapsed from the start of soldering, the operator is informed of the end of soldering and is alerted. be able to. Therefore, according to the present invention, the worker only needs to separate the heating target part from the soldering object in accordance with the above notification, and the destruction of the soldering object is prevented regardless of the skill level or carelessness of the worker. Is possible.

 Hereinafter, an embodiment of the present invention will be described with reference to the drawings. As an example of the solder melting apparatus, a soldering iron apparatus that melts solder for mounting electronic components and the like on a substrate will be described.

 FIG. 1 is a configuration block diagram of a soldering iron device according to an embodiment of the present invention. As shown in this figure, this soldering iron device includes a one-chip microcomputer (control means) 1, a tip (heating target part) 2, a heater 3, a first temperature sensor (temperature detection means) 4, and a power transformer 5. , Thyristor 6, zero cross detector 7, power supply circuit 8, first amplifier 9, second temperature sensor 10, second amplifier 11, multiplexer 12, A / D converter 13, switch 14, buzzer (notification means) 15, buffer amplifier 16, an operation panel 17, a display 18, an operation switch 19, a buffer 20, a transistor 21, an oscillation circuit 22, a reset switch 23, and an EEPROM (Electronically Erasable and Programmable Read Only Memory) 24.

 The one-chip microcomputer 1 controls the operation of each component described below according to a control program stored in a ROM (Read Only Memory) provided therein. As this one-chip microcomputer 1, in addition to the ROM, a microcomputer provided with a RAM (Random Access Memory), various timer input / output interfaces and the like is used.

 The tip 2 is a tip provided in a soldering iron portion of the present soldering iron device, and includes a heater 3 and a first temperature sensor 4. One end of the heater 3 is connected to one end of the secondary winding of the power transformer 5, and the other end of the secondary winding of the power transformer 5 is connected to the other end of the heater 3 via a thyristor 6 whose ON / OFF is controlled by the one-chip microcomputer 1. It is connected to the. That is, the heater 3 heats the tip 2 to a predetermined temperature in accordance with the output current control of the power transformer 5 by the thyristor 6. The first temperature sensor 4 detects the heating temperature of the tip 2 and outputs a first temperature detection signal indicating the heating temperature to the first amplifier 9.

 The power transformer 5 lowers the commercial power supplied from the outside and outputs the AC voltage after the low voltage to the heater 3, the zero cross detector 7 and the power circuit 8. The thyristor 6 controls the output current of the power transformer 5 flowing through the heater 3 by ON / OFF control by the one-chip microcomputer 1. The zero cross detector 7 detects the zero cross position of the AC voltage input from the power transformer 5 and outputs it to the one-chip microcomputer 1. The one-chip microcomputer 1 performs ON / OFF control of the thyristor 6 based on the zero-cross position detected by the zero-cross detector 7.

 The power supply circuit 8 rectifies the AC voltage input from the power supply transformer 5 and supplies a DC power supply voltage such as ± 5 V and +3 V to each part in the soldering iron device. The first amplifier 9 amplifies the first temperature detection signal input from the first temperature sensor 4 and outputs the amplified signal to one selection terminal of the multiplexer 12.

 The second temperature sensor 10 detects the cold junction temperature of the first temperature sensor 4 and outputs a second temperature detection signal indicating the cold junction temperature to the second amplifier 11. The second amplifier 11 amplifies the second temperature detection signal and outputs it to the other selection terminal of the multiplexer 12. The multiplexer 12 alternatively outputs the first temperature detection signal or the second temperature detection signal to the A / D converter (analog / digital converter) 13 according to the request of the one-chip microcomputer 1. The A / D converter 13 converts an input signal (first temperature detection signal or second temperature detection signal) that is an analog signal into a digital signal and outputs the digital signal to the one-chip microcomputer 1.

 The switch 14 alternatively outputs either the power supply voltage + 5V or + 3V to the buzzer 15 according to the request of the one-chip microcomputer 1. The buzzer 15 sends an alarm sound to the outside based on the alarm generation signal input from the one-chip microcomputer 1 through the buffer amplifier 16 and the volume defined by the power supply voltage alternatively input from the switch 14. Output. The buffer amplifier 16 amplifies the alarm generation signal input from the one-chip microcomputer 1 and outputs it to the buzzer 15.

 The operation panel 17 is provided in an operation box of the soldering iron apparatus, and includes a plurality of indicators 18 and operation switches 19. Each operation terminal of the display 18 is connected to the one-chip microcomputer 1 through the buffer 20, and the common terminal is connected to the collector terminal of the transistor 21. Each base terminal of the transistor 21 is connected to the one-chip microcomputer 1 so that a power supply voltage of, for example, +5 V is supplied to the common terminal of each display 18 in accordance with the base signal output from the one-chip microcomputer 1. It has become. The operation switch 19 is inserted between each collector terminal and the one-chip microcomputer 1 and outputs the switching operation information to the one-chip microcomputer 1. The buffer 20 buffers the display signal input from the one-chip microcomputer 1 and outputs the display signal to the display 18 via each operation terminal. That is, the display 18 displays information corresponding to the display signal.

 FIG. 2 shows the configuration of the operation panel 17. In this figure, reference numeral 19a denotes a numerical value input switch for inputting various setting values to be described later. The setting value input from the numerical value input switch 19a is displayed on the setting numerical value display 18a. 19b is a display digit shift switch for operating the digit shift of the numerical value displayed on the set numerical value display 18a, 19c is a parameter selector switch for switching the input mode of the numerical value input from the numerical value input switch 19a, and 19d is the above-mentioned various set values. This is a key lock switch for switching between the key lock setting to be held and the release thereof. When the key lock switch 19d is operated and the soldering iron device is set to the key lock setting state, the key lock setting lamp 18b is turned on. Also. Reference numeral 18c is a measurement temperature indicator for displaying the heating temperature of the tip 2 detected by the first temperature sensor 4, 18d is a heater energizing lamp that is turned on when the heater 3 is energized, and 18e is an alarm from the one-chip microcomputer 1. This is an alarm lamp (notification means) that is lit while a generation signal is being output.

 Further, in FIG. 1, the oscillation circuit 22 generates a basic clock signal of the one-chip microcomputer 1 and outputs the basic clock signal to the one-chip microcomputer 1. The reset switch 23 is for initializing the one-chip microcomputer 1 by the switching operation. The EEPROM 24 stores the setting state of the soldering iron device such as various setting values inputted from the numerical value input switch 19a and the key lock setting state by the key lock switch 19d.

 Next, the operation of the soldering iron device configured as described above will be described with reference to the flowchart of FIG. In the following, as shown in FIG. 4, an electronic component (for example, a transistor or a capacitor) 100 with a lead wire 101 is inserted into the through hole 201 from one surface of the printed circuit board 200 and the other surface of the printed circuit board 200. In the following description, it is assumed that the electronic component 100 is mounted on the printed circuit board 200 by bonding the wiring pattern 202 formed on the lead wire 101 and the lead wire 101 of the electronic component 100 with solder.

 FIG. 5 shows the temperature change of the tip 2 and the temperature change of the electronic component 100 as the soldering object in the soldering operation as shown in FIG. When using this soldering iron device, as shown in FIG. 5, the normal set temperature TM3 of the tip 2 in the soldering iron device, the soldering start time t1 (that is, the tip 2 is soldered or soldered). It is assumed that the tip temperature decrease amount ΔTM and the appropriate soldering time T1 used for detecting the electronic component 100 that is the target object) are input in advance by operating the numerical input switch 19a or the like. The one-chip microcomputer 1 is assumed to store these setting information in the EEPROM 24.

 Here, as shown in FIG. 5, the soldering time T1 is shorter than the time from the soldering start time t1 to the time when the electronic component 100 reaches the destruction temperature TM2, that is, the time T2 until the electronic component 100 is destroyed. And it is set longer than time T3 when the electronic component 100 reaches the solder melting temperature TM1. The soldering time T1 is the normal set temperature TM3 of the tip 2, the type of the electronic component 100 that is the soldering object, the configuration of the base printed circuit board 200 (the thermal structure of the substrate layer structure and the wiring pattern). Therefore, it is desirable to change the setting appropriately according to these conditions.

 In FIG. 3, when power is supplied to the soldering iron device, the one-chip microcomputer 1 reads the normal set temperature TM3 from the EEPROM 24, sets it to the control temperature of the tip 2, and turns on the thyristor 6. / OFF control is performed to control energization of the heater 3 so that the temperature of the tip 2, that is, the temperature detected by the first temperature sensor 4 becomes the normal set temperature TM3 (step S1). In the present embodiment, as shown in FIG. 5, the heater 3 is controlled so that the temperature of the tip 2 reaches the normal set temperature TM3 at time t0, and thereafter the temperature of the tip 2 is kept constant. It is assumed that

 Subsequently, the one-chip microcomputer 1 reads the tip temperature decrease amount ΔTM from the EEPROM 24, and the temperature of the tip 2, that is, the temperature detected by the first temperature sensor 4 is changed from the normal set temperature TM3 to the tip temperature. It is monitored whether or not the amount has decreased by the amount of decrease ΔTM (step S2). When soldering is started, the temperature of the tip 2 decreases when the tip 2 comes into contact with the solder or the electronic component 100 that is the soldering target. Thus, the tip 2 is moved from the normal set temperature TM3. It is possible to detect the time point when the temperature is decreased by the amount of the previous temperature decrease ΔTM (the time point when the predetermined temperature is decreased) as the soldering start time point.

 As described above, when the one-chip microcomputer 1 detects that the temperature of the tip 2 has decreased by the tip temperature decrease amount ΔTM, that is, detects the soldering start time (step S3), soldering from the EEPROM 24 is performed. The time T1 is read, and the time measurement of the soldering time T1 is started (step S4). In the present embodiment, as shown in FIG. 5, it is assumed that time t1 is detected as the soldering start time, and the time measurement of the soldering time T1 is started from the time t1.

 As shown in FIG. 5, the temperature of the tip 2 decreases to a certain temperature from the soldering start time t1, but the heater 3 is controlled so that the tip 2 is maintained at the normal set temperature TM3 during this time. Therefore, the temperature of the tip 2 gradually rises and is maintained at a temperature lower than the normal set temperature TM3. This is because the temperature does not completely reach the normal set temperature TM3 while the tip 2 is in contact with the solder or the electronic component 100 (that is, during soldering).

 Then, the one-chip microcomputer 1 determines whether or not the soldering time T1 has elapsed from the soldering start time (step S5), and when it is determined that the soldering time T1 has not elapsed (NO), the trowel It is determined whether or not the previous temperature has returned to the normal set temperature TM3 (step S6). That is, as described above, while the tip 2 is in contact with the solder or the electronic component 100 (that is, during soldering), the temperature does not completely reach the normal set temperature TM3, but this is reversed. In other words, when the worker finishes soldering and separates the tip 2 from the electronic component 100, it means that the temperature of the tip 2 returns to the normal set temperature TM3. Therefore, by determining whether or not the temperature of the tip 2 has returned to the normal set temperature TM3, it is possible to determine whether or not the worker has finished soldering.

 In such a step S6, when the temperature of the tip 2 has not returned to the normal set temperature TM3 (NO), the one-chip microcomputer 1 proceeds to the process of step S5, while the temperature of the tip 2 is When the temperature has returned to the normal set temperature TM3, that is, when the worker finishes the soldering (YES), the time-keeping process is finished because the soldering time T1 no longer needs to be timed (step S7). Transition to processing.

 On the other hand, when it is determined in step S5 that the soldering time T1 has elapsed from the soldering start time (YES), the one-chip microcomputer 1 outputs an alarm generation signal to the buzzer 15 via the buffer amplifier 16. An alarm sound is generated and the alarm lamp 18e on the operation panel 17 is turned on (step S8). Thereby, it is possible to notify the worker of the end of soldering, call attention, and prompt the end of soldering. Then, the one-chip microcomputer 1 determines whether or not the temperature of the tip 2 has returned to the normal set temperature TM3 (step S9). If the temperature of the tip 2 has not returned to the normal set temperature TM3, that is, When the worker keeps the tip 2 in contact with the electronic component 100 despite the end of soldering (NO), the process of step S8 is continued. That is, until the operator finishes soldering and the temperature of the tip 2 returns to the normal set temperature TM3, the alarm generation signal is continuously output and the alarm sound is generated from the buzzer 15 and the alarm lamp 18e is turned on. to continue. In step S9, if the temperature of the tip 2 has returned to the normal set temperature TM3, that is, if the worker has finished soldering (YES), the one-chip microcomputer 1 proceeds to the processing in step S2. .

 As described above, according to the present soldering iron device, the worker only needs to separate the tip 2 from the electronic component 100 that is the object to be soldered according to the alarm of the buzzer 15 or the alarm lamp 18e. It is possible to prevent the soldering object from being destroyed regardless of carelessness.

In addition, this invention is not limited to the said embodiment, For example, the following modifications can be considered.
(1) In the above embodiment, when the predetermined time has passed without the temperature of the tip 2 returning to the normal set temperature TM3 after the soldering time T1, the heating of the tip 2 by the heater 3 is stopped. The function may be given to the one-chip microcomputer 1. This prevents the tip 2 from being kept in contact with the electronic component 100 for some reason and preventing the electronic component 100 from being destroyed for some reason despite the fact that the alarm has occurred after the soldering time T1 has elapsed. be able to. Of course, the predetermined time here is set shorter than the time T3 when the electronic component 100 is destroyed. Further, after the heating of the tip 2 is stopped as described above, when the reset instruction is input by the operation of the operation panel 17 by the operator, the state may return to the state of step S1 in FIG. .

(2) In the above embodiment, an alarm is generated when the soldering time T1 has elapsed, so that the worker is notified that the soldering time T1 has elapsed (that is, the end of soldering). In addition to this, as a method of notifying the worker that the soldering time T1 has elapsed, the time of the soldering time T1 is started from the soldering start time t1 and an alarm signal is output, and the soldering time T1 has elapsed. In this case, the one-chip microcomputer 1 may have a function of stopping the output of the alarm generation signal. That is, the alarm is continuously generated during the soldering operation, and when the soldering time T1 has elapsed, the alarm is stopped to notify the worker of the end of the soldering.

  The operation of the one-chip microcomputer 1 in such a modification will be specifically described with reference to the flowchart of FIG. 6 are the same as the processes in steps S1 to S3 in FIG. 3, and thus the description thereof will be omitted. Hereinafter, the processes in and after step S13 will be described.

 In step S12, the one-chip microcomputer 1 detects that the temperature of the tip 2 has dropped by the tip temperature drop amount ΔTM, that is, when the soldering start time is detected, reads the soldering time T1 from the EEPROM 24. Then, the timing of the soldering time T1 is started, and an alarm sound is generated by outputting an alarm generation signal to the buzzer 15 via the buffer amplifier 16, and the alarm lamp 18e on the operation panel 17 is turned on (step S13). . Note that the volume of the alarm sound in this modification is preferably smaller than that in the above embodiment, and the sound pattern is preferably set to a pattern that does not give the operator a great discomfort. The reason is that in this modified example, an alarm sound is continuously generated during the soldering operation, so that the alarm sound prevents the worker from concentrating on the soldering operation.

  Then, the one-chip microcomputer 1 determines whether or not the soldering time T1 has elapsed from the soldering start time (step S14), and if it is determined that the soldering time T1 has not elapsed (NO), the trowel It is determined whether or not the temperature of the first 2 has returned to the normal set temperature TM3 (step S15). In step S15, if the temperature of the tip 2 has not returned to the normal setting temperature TM3 (NO), the one-chip microcomputer 1 proceeds to the processing of step S14, while the temperature of the tip 2 is set to the normal setting. When the temperature has returned to TM3, that is, when the worker finishes the soldering (YES), it is no longer necessary to time the soldering time T1, so the timing process is terminated and the output of the alarm generation signal is stopped ( Step S16), and then the process proceeds to Step S2.

 On the other hand, if it is determined in step S14 that the soldering time T1 has elapsed from the soldering start time (YES), the one-chip microcomputer 1 stops outputting the alarm generation signal (step S17). As a result, the alarm sound of the buzzer 15 is stopped and the alarm lamp 18e is extinguished, so that it is possible to notify the operator of the end of soldering and alert the operator to end the soldering. Then, the one-chip microcomputer 1 determines whether or not the temperature of the tip 2 has returned to the normal set temperature TM3 (step S18). If the temperature of the tip 2 has returned to the normal set temperature TM3, that is, When the worker finishes soldering (YES), the process proceeds to step S2.

 On the other hand, in step S18, the one-chip microcomputer 1 moves the tip 2 to the electronic component 100 when the temperature of the tip 2 has not returned to the normal set temperature TM3, that is, although the worker has finished soldering. (NO), it is determined whether or not a predetermined time has elapsed after the soldering time T1 has elapsed (step S19). In this step S19, if the predetermined time has not elapsed since the soldering time T1 has elapsed (NO), the one-chip microcomputer 1 proceeds to the processing of step S18, while the soldering time T1 has elapsed. If a predetermined time has passed since the start of the heating (YES), the heating of the tip 2 by the heater 3 is stopped (step S20). By the processing of these steps S19 and S20, as in the modification described in (1), it is possible to prevent the electronic component 100 from being destroyed due to the tip 2 being kept in contact with the electronic component 100 for some reason. Can do. Of course, the predetermined time here is set shorter than the time T2 when the electronic component 100 is destroyed. Further, after the heating of the tip 2 is stopped as described above, when the reset instruction is input by the operation of the operation panel 17 by the operator, the state may return to the state of step S10 in FIG. .

(3) In the said embodiment, the case where the 1st temperature sensor 4 and the heater 3 which are temperature detection means were provided in the tip 2 was illustrated and demonstrated. The first temperature sensor 4 and the heater 3 may be provided separately in the tip 2 as shown in FIG. 1, or the first temperature sensor 4 and the heater 3 are integrally formed using, for example, a thermocouple. A configuration may be adopted. Furthermore, a configuration in which the first temperature sensor 4 is provided outside the tip 2 may be employed.

(4) In the above embodiment, the soldering iron device has been described as an example of the solder melting device. However, the present invention is not limited to this, and the tip 2 is configured in a nozzle shape and melted from the nozzle-shaped tip 2. The present invention can also be applied to a solder removing device that sucks and removes solder in a state.

1 is a configuration block diagram of a soldering iron device according to an embodiment of the present invention. It is a figure which shows the structural example of the operation panel 17 in the soldering iron apparatus which concerns on one Embodiment of this invention. 6 is a flowchart showing the operation of the soldering iron device according to the embodiment of the present invention. It is the 1st explanatory view about operation of the soldering iron device concerning one embodiment of the present invention. It is the 2nd explanatory view about operation of the soldering iron device concerning one embodiment of the present invention. It is a modification of the flowchart which shows operation | movement of the soldering iron apparatus which concerns on one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... One-chip microcomputer, 2 ... Tip, 3 ... Heater, 4 ... 1st temperature sensor, 5 ... Power supply transformer, 6 ... Thyristor, 7 ... Zero cross detector, 8 ... Power supply circuit, 9 ... 1st amplifier, 10 2nd temperature sensor, 11 ... 2nd amplifier, 12 ... multiplexer, 13 ... A / D converter, 14 ... switch, 15 ... buzzer, 16 ... buffer amplifier, 17 ... operation panel, 18 ... display, 19 ... operation switch 20 ... buffer, 21 ... transistor, 22 ... oscillation circuit, 23 ... reset switch, 24 ... EEPROM

Claims (4)

A solder melting apparatus that melts solder by heating a predetermined heating target portion to a normal set temperature with a heater,
Temperature detecting means for detecting the temperature of the heating target part;
A notification control means for notifying the outside that a predetermined soldering time has elapsed from the soldering start time when a temperature at which the temperature of the heating target part has decreased by a predetermined temperature from the normal set temperature is set as a soldering start time; ,
Equipped with,
The notification control means includes
Control means for starting time measurement of the soldering time from the soldering start time point, and outputting an alarm signal when the soldering time has elapsed;
Informing means for generating an alarm toward the outside according to the alarm generation signal,
Have
The control means terminates the time measurement of the soldering time when the temperature of the heating target portion returns to the normal set temperature before the soldering time elapses from the soldering start time point. Solder melting equipment. 2. The solder melting apparatus according to claim 1 , wherein, after the soldering time has elapsed, the control means continues outputting the alarm generation signal until the temperature of the heating target portion returns to the normal set temperature . A solder melting apparatus that melts solder by heating a predetermined heating target portion to a normal set temperature with a heater,
Temperature detecting means for detecting the temperature of the heating target part;
A notification control means for notifying the outside that a predetermined soldering time has elapsed from the soldering start time when a temperature at which the temperature of the heating target part has decreased by a predetermined temperature from the normal set temperature is set as a soldering start time; ,
Comprising
The notification control means includes
Control means for starting time measurement of the soldering time from the soldering start time point and outputting an alarm generation signal, and stopping the output of the alarm generation signal when the soldering time has elapsed;
Informing means for generating an alarm toward the outside according to the alarm generation signal,
Have
When the temperature of the heating target portion has returned to the normal set temperature before the soldering time has elapsed from the soldering start time, the control means ends the time measurement of the soldering time and generates the alarm. A solder melting apparatus , wherein output of a signal is stopped . The control means stops heating of the heating target portion by the heater when a predetermined time has passed without the temperature of the heating target portion returning to the normal set temperature after the soldering time has elapsed. The solder melting apparatus according to any one of claims 1 to 3 .

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