Intelligent temperature control soldering tin repair method, device and equipment and storage medium

Abstract

The invention relates to the technical field of intelligent temperature control, and discloses an intelligent temperature control soldering tin repairing method, device and equipment and a storage medium. The method comprises the steps that the preheating temperature of a working table, the real-time temperature of a soldering bit and the temperature of a PCB substrate are collected, and a first heat conduction coefficient between the table and the soldering bit and a second heat conduction coefficient between the soldering bit and a welding spot are calculated; adjusting the target temperature of the tabletop; the first PID controller outputs a first PID output signal according to the table-board target temperature to drive the workbench to heat, the second PID controller outputs a second PID output signal to drive the soldering bit to raise the temperature and calculates the current margin to modulate the second PID output signal to obtain a third PID output signal, the start of welding flux melting is determined, and the second PID controller outputs a second PID output signal according to the table-board target temperature to drive the workbench to heat. And the first PID output signal and the third PID output signal are frozen to maintain the preset welding time, and current limiting or heating turn-off is executed, so that the problem of non-uniform heating of a welding spot caused by independent temperature control of the solder tip and the table top in the prior art is solved, and accurate and controllable heating power is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of intelligent temperature control, and in particular to an intelligent temperature control rework soldering method, device, equipment and storage medium. BACKGROUND

[0002] In the process of rework soldering of electronic products, the components on the PCB substrate need to be disassembled and re-soldered, and the temperature control accuracy of this process is extremely high. In the traditional rework process, the temperature control of the soldering iron head and the preheating temperature control of the workbench are independent of each other, and each uses an independent temperature feedback loop for adjustment, which makes the heat source of the soldering point area unable to cooperate.

[0003] This independent control mode has the following technical problems: first, the soldering iron head and the workbench preheating temperature cannot be dynamically adjusted according to the actual heat flow distribution, which may cause the workbench to overheat and cause heat backflow or the soldering iron head to overcompensate due to insufficient workbench temperature, resulting in uneven heating of the soldering point; second, the heating current lacks an effective modulation mechanism, and transient current impact may cause thermal damage to sensitive components; third, the soldering process relies on the experience of the operator to judge, and cannot accurately identify the solder melting time and control the cooling rate. SUMMARY

[0004] The present application provides an intelligent temperature control rework soldering method, device, equipment and storage medium, thereby solving the problem of uneven heating of the soldering point caused by independent control of the soldering iron head and the workbench temperature in the prior art, and realizing accurate control of the heating power.

[0005] The first aspect of the present application provides an intelligent temperature control rework soldering method, which comprises: Collecting the workbench preheating temperature, the real-time temperature of the soldering iron head and the temperature of the PCB substrate, calculating the first heat conduction coefficient between the workbench and the soldering iron head and the second heat conduction coefficient between the soldering iron head and the soldering point; Adjusting the target temperature of the workbench based on the first heat conduction coefficient and the second heat conduction coefficient; A first PID controller outputs a first PID output signal to drive the workbench heating according to the target temperature of the workbench, a second PID controller outputs a second PID output signal to drive the soldering iron head to heat up and modulates the second PID output signal by calculating the current margin to obtain a third PID output signal; Monitoring the second heat conduction coefficient to determine the start of solder melting, freezing the first PID output signal and the third PID output signal to maintain a preset soldering time; Based on the cooling rate of the PCB substrate temperature, the target temperature of the workbench is adjusted to control the cooling process, and the heating is limited or turned off.

[0006] In combination with the first aspect, in a first implementation manner of the first aspect of the present application, the worktable surface preheating temperature, the real-time temperature of the soldering iron tip and the PCB substrate temperature are collected, and the first heat conduction coefficient between the worktable surface and the soldering iron tip and the second heat conduction coefficient between the soldering iron tip and the soldering point are calculated, including: collecting the worktable surface preheating temperature, the real-time temperature of the soldering iron tip and the PCB substrate temperature; calculating the first heat conduction coefficient according to the first temperature difference between the real-time temperature of the soldering iron tip and the worktable surface preheating temperature, the first contact thermal resistance between the worktable surface and the soldering iron tip and the sampling time interval; calculating the second heat conduction coefficient according to the second temperature difference between the real-time temperature of the soldering iron tip and the PCB substrate temperature, the second contact thermal resistance of the soldering layer and the sampling time interval.

[0007] In combination with the first aspect, in a second implementation manner of the first aspect of the present application, the adjustment of the worktable surface target temperature based on the first heat conduction coefficient and the second heat conduction coefficient includes: calculating a heat conduction fusion coefficient according to the ratio of the first heat conduction coefficient to the sum of the first heat conduction coefficient and the second heat conduction coefficient; determining that the worktable surface preheating temperature is too high when the heat conduction fusion coefficient is greater than a first threshold value, and determining that the worktable surface preheating temperature is insufficient when the heat conduction fusion coefficient is less than a second threshold value; calculating a worktable surface temperature adjustment amount based on the deviation of the heat conduction fusion coefficient from a preset ideal value and a preset adjustment coefficient, and adjusting the worktable surface target temperature according to the reference worktable surface temperature and the worktable surface temperature adjustment amount.

[0008] In combination with the first aspect, in a third implementation manner of the first aspect of the present application, the first PID controller outputs a first PID output signal to drive the worktable heating according to the worktable surface target temperature, and the second PID controller outputs a second PID output signal to drive the soldering iron tip to heat up and calculates a current margin to modulate the second PID output signal to obtain a third PID output signal, including: The first PID controller calculates a first control error of the worktable surface target temperature and the worktable surface preheating temperature, and outputs a first PID output signal to drive the worktable heating to the preheating temperature and stabilize based on the first control error; The second PID controller calculates a second control error of the soldering iron tip target temperature and the real-time temperature of the soldering iron tip according to the soldering iron tip target temperature determined by looking up the table according to the type of the element to be repaired; The second PID controller outputs a second PID output signal to drive the soldering iron tip to heat up based on the second control error, and monitors the soldering iron tip heating rate and controls it within a preset heating rate range; The first PID output signal and the second PID output signal are distributed according to the heat conduction fusion coefficient, the current margin is calculated based on the real-time heating current, the second PID output signal is modulated by a current limiting coefficient, and a third PID output signal is obtained.

[0009] With reference to the first aspect, in a fourth implementation manner of the first aspect, the first PID output signal and the second PID output signal are distributed according to the heat conduction fusion coefficient, the current margin is calculated based on the real-time heating current, the second PID output signal is modulated by a current limiting coefficient, and a third PID output signal is obtained, including: When the heat conduction fusion coefficient is greater than a first threshold value, the first PID output signal is adjusted by a first proportional coefficient, and when the heat conduction fusion coefficient is less than a second threshold value, the second PID output signal is adjusted by a second proportional coefficient; The real-time heating current of the iron tip heating loop is collected, and the current margin is calculated according to the real-time heating current and a peak current threshold value determined according to the iron tip power; A current limiting coefficient is determined according to the current margin, and the second PID output signal is modulated based on the current limiting coefficient, and a third PID output signal is obtained.

[0010] With reference to the first aspect, in a fifth implementation manner of the first aspect, the second heat conduction coefficient is monitored to determine that the solder starts to melt, and the first PID output signal and the third PID output signal are frozen to maintain a preset welding time, including: The difference between the second heat conduction coefficient of the current period and the second heat conduction coefficient of the previous period is calculated, and the difference and the second heat conduction coefficient of the previous period are calculated by ratio to obtain a heat conduction coefficient change rate; When the heat conduction coefficient change rate is greater than a preset change rate threshold value, it is determined that the solder starts to melt, and a control signal freezing instruction is triggered; The first PID output signal and the third PID output signal are locked as current values based on the control signal freezing instruction and maintained for a preset welding time.

[0011] With reference to the first aspect, in a sixth implementation manner of the first aspect, the target temperature control cooling process of the table top is regulated based on the cooling rate of the PCB substrate temperature, and the current limiting or the heating is turned off, including: The cooling rate of the PCB substrate temperature is calculated, and it is determined whether the cooling rate is within a preset cooling rate range to obtain a cooling rate deviation state; When the cooling rate deviation state is too fast, the first PID output signal is increased to raise the target temperature of the table top, and when the cooling rate deviation state is too slow, the first PID output signal is decreased. When the worktable static voltage exceeds the preset static threshold, the third PID output signal is current-limited, and when the leakage current exceeds the preset leakage current threshold, the heating is turned off.

[0012] The second aspect of the present application provides an intelligent temperature control repair soldering device, which comprises: The acquisition module is configured to acquire a worktable preheating temperature, a real-time temperature of an iron tip, and a PCB substrate temperature, and to calculate a first heat conduction coefficient between the table top and the iron tip and a second heat conduction coefficient between the iron tip and a soldering point. The adjustment module is configured to adjust a target temperature of the table top based on the first heat conduction coefficient and the second heat conduction coefficient. The driving module is configured to drive the worktable to heat up according to a first PID output signal output by a first PID controller based on the target temperature of the table top, to drive the iron tip to heat up according to a second PID output signal output by a second PID controller, and to calculate a current margin to modulate the second PID output signal to obtain a third PID output signal. The maintenance module is configured to monitor the second heat conduction coefficient to determine the start of solder melting, and to freeze the first PID output signal and the third PID output signal to maintain a preset welding time. The execution module is configured to control a cooling process by regulating the target temperature of the table top based on a cooling rate of the PCB substrate temperature, and to perform current limiting or turn off the heating.

[0013] The third aspect of the present application provides an electronic device, which comprises a memory and at least one processor, the memory has instructions stored therein, and the at least one processor invokes the instructions in the memory to enable the electronic device to perform the intelligent temperature control repair soldering method described above.

[0014] The fourth aspect of the present application provides a computer-readable storage medium, which has instructions stored therein, and when the instructions are run on a computer, the computer is enabled to perform the intelligent temperature control repair soldering method described above.

[0015] Compared with the prior art, the application has the following beneficial effects: by establishing a multi-point temperature acquisition system to obtain the workbench preheating temperature, the iron tip real-time temperature and the PCB substrate temperature, calculating the first heat conduction coefficient between the workbench and the iron tip and the second heat conduction coefficient between the iron tip and the solder joint, and then constructing the heat conduction fusion coefficient to quantify the contribution proportion of the workbench preheating to the solder joint temperature, the accurate characterization of the double heat source heat flow distribution is realized. Based on the heat conduction fusion coefficient, the target temperature of the workbench is dynamically adjusted, and the workbench heating and the iron tip heating are respectively driven through the cascade PID control structure, the power proportion of the two PID output signals is real-timely distributed according to the heat conduction fusion coefficient, and the problem of uneven heating of the solder joint caused by independent control of the iron tip and the workbench temperature in the prior art is solved. The peak current modulation mechanism is introduced, the current margin is calculated to obtain the current limiting coefficient for modulating the second PID output signal, and the thermal damage of sensitive elements caused by instantaneous current impact is effectively prevented. By monitoring the mutation characteristics of the second heat conduction coefficient, the solder melting start time is automatically determined, and the control signal is frozen to maintain a stable welding temperature. In the cooling stage, the target temperature of the workbench is closed-loop regulated based on the cooling rate of the PCB substrate temperature, so that the cooling rate is ensured to be in a reasonable range to avoid solder joint cracks, and the heating power is accurately controllable by combining the real-time monitoring of the static voltage and the leakage current to execute current limiting or heating shutdown. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0017] The structures, proportions, sizes, etc. shown in the drawings of the present specification are only used to cooperate with the content disclosed in the present specification, to enable those skilled in the art to understand and read, and are not used to limit the defined conditions under which the present application can be implemented, so they do not have technical significance. Any modification of structure, change of proportion relationship or adjustment of size, which does not affect the effects and purposes that can be achieved by the present application, should still fall within the scope of the technical content disclosed by the present application.

[0018] Figure 1 is a flowchart of the intelligent temperature control repair soldering method provided by the embodiment of the present application; Figure 2 is a structural schematic block diagram of the intelligent temperature control repair soldering device provided by the embodiment of the present application; Figure 3 is a structural schematic block diagram of the electronic device provided by the embodiment of the present application. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of the present application.

[0020] The flowcharts shown in the drawings are only exemplary and do not necessarily include all the contents and operations / steps, nor are they necessarily executed in the described order. For example, some operations / steps can be further decomposed, combined or partially merged, so that the actual execution order can be changed according to the actual situation.

[0021] It should also be understood that the terms used in this specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in the specification and the appended claims of the present application, the singular forms "a", "an" and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0022] It should be further understood that the term "and / or" used in the specification and the appended claims of the present application means any combination of one or more of the associated listed items and all possible combinations, and includes these combinations. Please refer to Figure 1 One embodiment of the intelligent temperature control repair soldering method in the embodiments of the present application includes: Step 100, collect the workbench preheating temperature, the real-time temperature of the soldering iron tip and the PCB substrate temperature, calculate the first heat conduction coefficient between the workbench and the soldering iron tip and the second heat conduction coefficient between the soldering iron tip and the soldering point; Specifically, a temperature monitoring network composed of three types of sensors is established, in which the preheating temperature of the workbench is collected in real time by a K-type thermocouple embedded 3 mm deep in the workbench, and a MAX6675 chip with a digital cold-end compensation circuit is used to realize high-precision conversion of the temperature signal, and the temperature resolution of the chip is 0.25 °C; the real-time temperature of the soldering iron tip is measured by a PT100 platinum resistance temperature sensor embedded in the tip 5 mm away, the sensor uses a four-wire connection method to suppress lead resistance errors, and a special RTD conditioning chip MAX31865 is used to convert the digital signal, and the temperature resolution reaches 0.03125 °C; at the same time, the PCB substrate temperature is collected by an MLX90614 infrared temperature measurement module 150 mm above the soldering area perpendicular to the PCB, the field angle of the infrared temperature measurement module is set to 90 degrees and the focal point is aligned with the welding area, and the output is corrected by the emissivity to reflect the true substrate surface temperature, and the emissivity coefficient of the FR-4 material PCB is 0.90; the three groups of sensors are sampled synchronously at a frequency of 100 Hz and the clock signal is provided by the timer TIM2 of the main control chip STM32F407, and the temperature data is transmitted to the circular buffer in real time through the DMA mode, ensuring the continuity and low delay characteristics of data acquisition. After completing the temperature sampling, the first thermal conductivity coefficient is calculated according to the first temperature difference between the real-time temperature of the soldering iron tip and the preheating temperature of the workbench and the first contact thermal resistance between the workbench and the soldering iron tip, wherein the first contact thermal resistance is set to 0.15 K / W by pre-calibration experiment, and the sampling time interval is 10 ms; the second thermal conductivity coefficient is calculated according to the second temperature difference between the real-time temperature of the soldering iron tip and the PCB substrate temperature and the second contact thermal resistance of the solder layer, and the second contact thermal resistance is determined according to the solder type table, and the lead-free solder SAC305 is 0.08 K / W, and the leaded solder SnPb63 / 37 is 0.12 K / W. The calculation results of the above two thermal conductivity coefficients are written into the dual-port RAM in real time, and are continuously updated every 10 ms control period.

[0023] Step 200, adjusting the target temperature of the workbench based on the first thermal conductivity coefficient and the second thermal conductivity coefficient; Specifically, by taking the ratio of the first thermal conductivity coefficient and the sum of the first thermal conductivity coefficient and the second thermal conductivity coefficient as the calculation basis, a real-time dynamically changing thermal conduction fusion coefficient is constructed as the core criterion of the temperature control logic. When the thermal conduction fusion coefficient is greater than the first threshold value, for example, more than 0.6, it is determined that the current table preheating temperature is too high, which means that the heat conduction from the table to the soldering iron head is too much, which will cause heat backflow, so that the soldering iron head may still have temperature overshoot in the low power state. At this time, the workbench heating power is reduced to avoid waste and local overheating; when the fusion coefficient is less than the second threshold value, for example, less than 0.3, it is determined that the table preheating is insufficient, and the support of the table to the soldering point temperature is weak. The workbench target temperature or the soldering iron head heating power is appropriately increased to maintain the thermal balance of the welding temperature zone. The deviation between the current thermal conduction fusion coefficient and the ideal value is taken as the adjustment reference, and the dynamic adjustment amount of the table temperature is calculated by combining the preset adjustment coefficient, and the dynamic adjustment amount is added or deducted to the preset reference table temperature to form the updated table target temperature value. The preset reference temperature is set to 180℃ as the initial reference value of the preheating control, and the adjustment coefficient is selected as an empirical parameter according to the thermal response characteristics, for example, 1℃ correction amplitude corresponds to 0.01 deviation.

[0024] Step 300, the first PID controller outputs a first PID output signal to drive the workbench heating according to the table target temperature, the second PID controller outputs a second PID output signal to drive the soldering iron head to heat up and calculates the current margin to modulate the second PID output signal to obtain a third PID output signal; Specifically, the first PID controller obtains the updated target temperature of the table top, and calculates a first control error in combination with the real-time collected preheating temperature of the table top. The first control error reflects the deviation between the current actual temperature of the table top and the preset temperature. The first PID controller performs proportional, integral, and differential calculations based on the first control error as an input quantity, and outputs a first PID signal for driving the nichrome heating wire to heat to the target temperature. The table top temperature is maintained within ±2°C of the target value through closed-loop control to form a continuous and uniform preheating environment. According to the packaging type of the electronic components to be repaired, the corresponding target temperature of the soldering iron tip is extracted from the preset temperature database, for example, 330°C for 0402 / 0603 packaged resistors, 310°C for QFP / BGA packaged integrated circuits, and 350°C for connector assemblies. Then, the second PID controller compares the target temperature with the real-time temperature of the soldering iron tip collected at present, calculates a second control error, and outputs a second PID signal based on the second control error to drive the IGBT power device to control the heating power of the soldering iron tip. During the heating process, the heating rate of the soldering iron tip is calculated in real time and limited. When the heating rate exceeds 18°C / s, the PID output is limited to 85% of the current value, and when it is lower than 12°C / s, the output is increased to 120% of the original value, to prevent temperature shock damage to the solder joints. To achieve coordinated control between heat sources, the heat energy distribution ratio is adjusted according to the real-time change trend of the heat conduction fusion coefficient. When the heat conduction fusion coefficient is higher than 0.6, the first PID output is reduced to reduce the table top power, while the second PID output remains unchanged; when the heat conduction fusion coefficient is lower than 0.3, the table top heating level is maintained unchanged and the second PID output is increased to ensure that the soldering iron tip obtains sufficient compensation heat. On the basis of the above soldering iron tip heating control, a current protection mechanism is integrated. The heating loop current is collected in real time and compared with the preset peak current threshold to calculate the current margin. The current margin is used to evaluate the distance between the current level and the safety threshold. The current limiting coefficient is divided according to the margin interval, for example, when the margin is between 0.05 and 0.10, the current limiting coefficient is set to 0.70. The second PID output signal is modulated by the third PID signal with the coefficient.

[0025] Step 400, monitor the second heat conduction coefficient to determine the start of solder melting, freeze the first PID output signal and the third PID output signal to maintain a preset welding time; Specifically, the second thermal conductivity coefficient is continuously calculated by a high-frequency sampling mechanism at a period of 10 milliseconds during the soldering stage. The second thermal conductivity coefficient is determined by the temperature difference between the real-time temperature of the soldering iron tip and the temperature of the PCB substrate, as well as the contact thermal resistance of the solder layer and the sampling interval, and can effectively reflect the change state of the thermal conductivity of the solder joint interface. To identify the physical characteristics of the solder during the transition from solid to liquid state, the second thermal conductivity coefficient calculated in each control period is recorded and compared with the second thermal conductivity coefficient of the previous period. After obtaining the difference between the two, the second thermal conductivity coefficient of the previous period is divided by the second thermal conductivity coefficient of the previous period to obtain the relative change rate of the thermal conductivity coefficient, which reflects the sudden change characteristics of the contact thermal resistance due to the filling of liquid solder in the air gap and the sharp increase in heat flow flux at the moment of solder melting. When the thermal conductivity coefficient change rate exceeds the preset change rate threshold, for example, more than 30%, it is determined by the system that the solder has reached the melting point and started to melt, indicating that the soldering process has entered the critical stage. At this time, the control signal freeze command is triggered to stabilize the current heating state, avoiding temperature field disturbance caused by control quantity fluctuations and affecting the solder wetting effect and solder joint forming quality. In response to the freeze command, the first PID controller output of the table heating signal and the third PID signal after current limiting modulation, which is used to drive the soldering iron tip heating control signal, are respectively locked as the current output value at the trigger time, and no longer respond to subsequent error updates or external disturbances, and remain in the locked state for a complete preset soldering time period, which is set to 5 seconds or adjusted according to the type of solder and components, so that the solder can be fully melted, wetted and complete the metal bonding process of the pad and pin in the controlled heat field.

[0026] Step 500, based on the cooling rate of the PCB substrate temperature, the target temperature of the table is controlled to control the cooling process, and the current limiting or heating is turned off.

[0027] Specifically, the PCB substrate surface temperature is continuously collected after entering the cooling phase, and the temperature difference between two consecutive sampling time points is calculated every second period to obtain the cooling rate, which reflects the dynamic change trend of the substrate heat dissipation. The current cooling rate is compared with the preset cooling rate range, for example, the ideal range is set to 5-8℃ / s, and the cooling rate deviation state is judged accordingly. When it is determined that the cooling is too fast, that is, the temperature drop rate exceeds 8℃ / s, the output signal of the first PID controller is actively increased to increase the target temperature of the workbench surface, so as to form a heat buffer through the heating of the surface to slow down the temperature drop of the soldering area, prevent the crack of the solder joint caused by excessive thermal stress, and prevent the false welding caused by uneven solder shrinkage; if it is determined that the cooling is too slow, that is, the temperature drop rate is lower than 5℃ / s, the first PID output signal is reduced, which is equivalent to reducing the heating power of the surface, so that the soldering area completes the heat retreat process in a shorter time, improves the repair efficiency and guarantees the process rhythm. While executing the cooling control, the electrostatic state of the workbench surface is monitored synchronously, and the electrostatic voltage between the workbench surface and the ground is collected. When the detection value exceeds the set electrostatic threshold value, for example, 200V, it is determined that there is a risk of excessive static accumulation. At this time, the heating is not directly turned off, but the third PID output signal is executed. For example, the original output signal is attenuated to 30% amplitude to reduce the power output, which can prevent the damage of sensitive components caused by electrostatic discharge while maintaining the basic heat control demand. By integrating the power supply protection module to detect the leakage current difference value in the loop in real time, when the leakage current continuously exceeds the set threshold value, for example, 30mA, and maintains more than 50 milliseconds, the emergency shutdown logic is executed, including pulling down the gate voltage of the IGBT power device to the cutoff state and disconnecting the solid-state relay, so as to interrupt the heating of the surface and the power supply path of the iron head.

[0028] In a specific embodiment, the process of step 100 can specifically include the following steps: Collecting the preheating temperature of the workbench surface, the real-time temperature of the iron head, and the temperature of the PCB substrate; Calculating the first heat conduction coefficient according to the first temperature difference between the real-time temperature of the iron head and the preheating temperature of the workbench surface, the first contact thermal resistance between the workbench surface and the iron head, and the sampling time interval; Calculating the second heat conduction coefficient according to the second temperature difference between the real-time temperature of the iron head and the temperature of the PCB substrate, the second contact thermal resistance of the solder layer, and the sampling time interval.

[0029] Specifically, the preheating temperature of the workbench surface is collected by a K-type thermocouple embedded in the workbench structure at a depth of 3 mm. The K-type thermocouple is connected to a MAX6675 digital temperature collection chip, which has integrated cold-end compensation and digital SPI communication capabilities. This allows for high-precision, digital acquisition of the surface temperature with a resolution of 0.25°C and a frequency of 100Hz. The data is transmitted to the DMA buffer of the main control chip. Meanwhile, the real-time temperature of the soldering iron tip is collected by a PT100 platinum resistance temperature sensor located 5 mm inside the heating tip. A four-wire connection method is used to effectively eliminate the interference of transmission lead resistance on measurement accuracy. The output signal is converted to a digital signal by a MAX31865 conversion chip, with a resolution of 0.03125°C and a sampling frequency matching the surface temperature collection system. The third key temperature collection point is located 150 mm above the PCB substrate, using an MLX90614 infrared non-contact temperature sensor with a field of view angle of 90 degrees and a focal point pointing to the welding site. The emissivity parameter is adjusted to adapt to different PCB materials. For common FR-4 board materials, the emissivity is set to 0.90. The temperature sensor also feeds back the infrared temperature measurement results to the main control system at a frequency of 100Hz. Based on the physical heat conduction process, the first heat conduction coefficient between the workbench surface and the soldering iron tip and the second heat conduction coefficient between the soldering iron tip and the welding point are calculated. The first heat conduction coefficient describes the rate of heat transfer from the workbench surface to the soldering iron tip. The relationship is as follows: the first heat conduction coefficient is directly proportional to the difference between the real-time temperature of the soldering iron tip and the temperature of the workbench surface, and inversely proportional to the product of the preset first contact thermal resistance and the sampling time interval. The larger the temperature difference, the faster the heat transfer. The larger the contact thermal resistance or the shorter the heat transfer time, the lower the transfer efficiency. The first contact thermal resistance is calibrated by experiment and fixed at 0.15K / W, and the sampling time interval is 10 milliseconds. The second heat conduction coefficient measures the ability of heat transfer from the soldering iron tip to the welding point. The larger the difference between the temperature of the soldering iron tip and the temperature of the PCB surface, the higher the heat absorption rate of the welding point. The second heat conduction coefficient is calculated by dividing the temperature difference by the product of the solder layer contact thermal resistance and the time interval. Unlike the surface part, the contact thermal resistance is preset according to the type of solder, with 0.08K / W for SAC305 solder and 0.12K / W for SnPb63 / 37 solder. The type of solder is automatically identified before welding and the corresponding resistance value is loaded, and the heat conduction rate is calculated in combination with the real-time temperature difference and the time interval of 10 milliseconds.

[0030] In a specific embodiment, the process of performing step 200 can specifically include the following steps: calculating a heat conduction fusion coefficient according to the ratio of the first heat conduction coefficient to the sum of the first heat conduction coefficient and the second heat conduction coefficient; determining that the table preheating temperature is too high when the heat conduction fusion coefficient is greater than a first threshold value, and determining that the table preheating is insufficient when the heat conduction fusion coefficient is less than a second threshold value; calculating a table temperature adjustment amount based on a deviation amount of the heat conduction fusion coefficient from a preset ideal value and a preset adjustment coefficient, and adjusting the table target temperature according to the reference table temperature and the table temperature adjustment amount.

[0031] Specifically, the heat conduction fusion coefficient is obtained by ratio operation according to the first heat conduction coefficient and the sum of the first heat conduction coefficient and the second heat conduction coefficient, which reflects the heat flow distribution trend under the current working condition. The ratio changes between 0 and 1, and when the value is close to 1, it indicates that the table has stronger dominance over the overall heat flow. The heat conduction fusion coefficient is compared with two empirical threshold values. When the fusion coefficient is greater than a first threshold value, for example, 0.6, it is determined that the current worktable is in a state of preheating too high, which indicates that the heat released by the table has been excessively conducted upward to the soldering iron head, which is easy to cause local temperature overshoot and cause instability of the welding temperature zone. At this time, the table target temperature is actively reduced to weaken the influence of its heat source, thereby avoiding power redundancy and energy waste; when the fusion coefficient is less than a second threshold value, for example, 0.3, it is determined that the current table preheating level is insufficient, which indicates that the table has weak support capability for heat flow, and the soldering iron head needs to bear more heating load, thereby affecting the timing stability of the solder joint temperature. At this time, the table temperature is increased to achieve heat field balance. In order to realize the continuity and responsiveness of temperature adjustment, the deviation amount between the current fusion coefficient and the ideal target value is used as the basis for dynamic adjustment, and the table temperature adjustment amount is calculated in combination with a preset adjustment coefficient. The preset adjustment coefficient is set to 1℃ temperature correction amplitude per 0.01 deviation according to historical experiments, for example, when the fusion coefficient deviates from the ideal value 0.45 by more than ±0.1, the table target temperature is increased or decreased by 5℃ to 10℃ or more. The table temperature adjustment amount is superimposed with the reference table temperature to form a new table target temperature. The reference table temperature is set to 180℃ and is used as a set point for closed-loop control in the outer ring PID controller.

[0032] In a specific embodiment, the process of performing step 300 can specifically include the following steps: The first PID controller calculates a first control error of the table target temperature and the worktable preheating temperature, and outputs a first PID output signal based on the first control error to drive the worktable to preheat to the preheating temperature and stabilize; The soldering iron head target temperature is determined according to the type of the element to be repaired, and the second PID controller calculates a second control error of the soldering iron head target temperature and the real-time temperature of the soldering iron head; The second PID output signal is output based on the second control error to drive the soldering iron head to heat up, and the soldering iron head heating rate is monitored and controlled within a preset heating rate range; The first PID output signal and the second PID output signal are distributed according to a heat conduction fusion coefficient, the current margin is calculated based on a real-time heating current to obtain a current limiting coefficient to modulate the second PID output signal, and a third PID output signal is obtained.

[0033] Specifically, the first PID controller obtains the dynamically adjusted target temperature of the table top, and continuously collects the current preheating temperature of the table top. A first control error is calculated based on the difference between the two, which is used as an input variable of an outer loop PID regulator. After proportional, integral and differential algorithm operations, a first PID control signal is output, which is used to drive the nickel-chromium alloy heating wire arranged inside the table top to perform constant power heating. A solid state relay is excited at a fixed frequency to perform power on-off, so that the temperature of the table top gradually approaches the target set value and is maintained stable, and the temperature stable range is controlled within ±2℃. At the same time, according to the packaging type or process requirement of the components to be welded in the current repair task, the matching iron tip target temperature value is obtained from the preset database, for example, 330℃ for 0402 resistor, 310℃ for BGA chip, and 350℃ for high-power connector. The target temperature is input into the second PID controller, compared with the real-time collected iron tip temperature to obtain a second control error, and the second PID control signal is calculated and output based on the second control error, which is used to adjust the conduction time and PWM duty cycle of the IGBT power switching device, control the dynamic change of the iron tip heating power, and realize closed-loop control in the heating process. In order to prevent local thermal shock or deformation of the welding point caused by rapid heating, the iron tip heating rate is continuously monitored, and the temperature change rate is calculated in real time. When the heating rate exceeds 18℃ / s, the second PID output is automatically reduced to 85% of the current value, and when the heating rate is lower than 12℃ / s, the output is increased to 120% of the original value, so as to ensure stable temperature rise. The first PID and the second PID output signals are dynamically distributed based on the real-time updated heat conduction fusion coefficient. When the fusion coefficient is greater than 0.6, it means that the table top heat output is excessive, the first PID signal is halved, and the second PID output remains unchanged. When the fusion coefficient is less than 0.3, it means that the table top heat is insufficient, and the second PID signal output is enhanced while the table top heating is maintained. While performing iron tip temperature control, a current protection mechanism is introduced, the actual current of the heating circuit is collected in real time, and the current margin is calculated by comparing with the rated peak current threshold of the equipment. When the margin is small, the second PID output is modulated by a current limiting coefficient, and the current limiting coefficient is divided into 0.85, 0.70 or 0.50 according to the margin interval. The third PID output signal is obtained by multiplying the second PID signal by the current limiting coefficient.

[0034] The second PID output signal is output based on the second control error to drive the bit head to heat up, and after monitoring the bit head heating rate and controlling it within a preset heating rate range, the method further comprises: determining whether the real-time temperature of the bit head reaches a preset proportional threshold of the target temperature of the bit head, and triggering a control mode switching signal when the preset proportional threshold is reached to switch from the rapid heating mode to the fine temperature control mode; adjusting the integral coefficient and the differential coefficient of the second PID controller based on the control mode switching signal, adjusting the integral coefficient from a first integral coefficient value to a second integral coefficient value to enhance the steady-state accuracy, and adjusting the differential coefficient from a first differential coefficient value to a second differential coefficient value to enhance the anti-interference ability; calculating a fusion coefficient deviation of the heat conduction fusion coefficient from a preset ideal value, and compensating and adjusting the second integral coefficient value and the second differential coefficient value according to the fusion coefficient deviation when the fusion coefficient deviation exceeds a preset deviation threshold; and recalculating the second PID output signal based on the compensated integral coefficient and differential coefficient to establish a temperature platform to provide a stable thermal environment for welding operation.

[0035] The monitoring of the bit head heating rate and the control of the bit head heating rate within a preset heating rate range comprises: performing time differentiation calculation on the real-time temperature of the bit head to obtain the bit head heating rate in the current period; determining the deviation state of the bit head heating rate from the preset target heating rate, determining that the heating rate is too fast when the bit head heating rate is greater than a preset upper limit heating rate threshold, and determining that the heating rate is too slow when the bit head heating rate is less than a preset lower limit heating rate threshold; when the heating rate is too fast, calculating an overshoot of the bit head heating rate from the preset upper limit heating rate threshold, and reducing the second PID output signal based on the overshoot according to a first power limitation proportion coefficient to prevent temperature shock; and when the heating rate is too slow, calculating an insufficient amount of the bit head heating rate from the preset lower limit heating rate threshold, and enhancing the second PID output signal based on the insufficient amount according to a second power enhancement proportion coefficient to accelerate the heating process.

[0036] In a specific embodiment, the execution step of distributing the first PID output signal and the second PID output signal according to the heat conduction fusion coefficient, calculating a current margin based on the real-time heating current to obtain a current limiting coefficient to modulate the second PID output signal, and obtaining the third PID output signal can specifically include the following steps: When the heat conduction fusion coefficient is greater than a first threshold, the first PID output signal is adjusted by a first proportion coefficient, and when the heat conduction fusion coefficient is less than a second threshold, the second PID output signal is adjusted by a second proportion coefficient; The real-time heating current of the bit head heating circuit is collected, and a current margin is calculated based on the real-time heating current and a peak current threshold determined according to the bit head power; The current margin is determined to determine the current limiting coefficient, and the second PID output signal is modulated based on the current limiting coefficient to obtain a third PID output signal.

[0037] Specifically, a heat conduction fusion coefficient is calculated in real time, which is used to dynamically evaluate the proportion of heat flow occupied by the workbench in the soldering head heat conduction path. When the heat conduction fusion coefficient is greater than a first threshold value, for example, greater than 0.6, it indicates that the workbench contributes too much to the entire welding heat field, and a down-regulation operation is performed. The output signal of the first PID controller is attenuated by a set first proportional coefficient, for example, multiplied by 0.5, so that the heat output power of the workbench is reduced, thereby avoiding heat backflow causing the soldering head to rise too fast or power redundancy waste; when the fusion coefficient is lower than a second threshold value, for example, less than 0.3, it is judged that the workbench is not heated enough, and the soldering head needs to bear more heating tasks. At this time, the output signal of the second PID controller is enhanced by a second proportional coefficient, for example, increased by 20% or more, to compensate for the overall heat flow shortage and maintain the welding point temperature in an effective range. In the process of PID signal distribution based on heat flow structure, the actual current value of the soldering head heating loop is synchronously collected. The current value is collected through a Hall current sensor connected in series in the soldering head power supply loop, and is fed back to the main control chip through an operational amplifier amplification and ADC digital conversion. At the same time of collecting the real-time heating current, the peak current threshold value is determined according to the rated power of the soldering head currently used, for example, 18A for a 60W soldering head, 23A for a 90W soldering head, and 28A for a 120W soldering head. The real-time current is compared with the peak current threshold value to calculate the current margin. The current margin reflects the margin of the actual current from the peak safety upper limit. If the current margin is small, it means that the power output has approached the limit that the device can withstand. The current margin is divided into multiple control intervals, and a current limiting coefficient is configured for each interval. For example, when the margin is between 10% and 15%, the current limiting coefficient is set to 0.85, when it is between 5% and 10%, the current limiting coefficient is set to 0.70, and when it is lower than 5%, the current limiting coefficient is set to 0.50, so as to gradually strengthen the protection. The current limiting coefficient is multiplied with the second PID output signal to obtain a third PID output signal for controlling the soldering head heating circuit.

[0038] In a specific embodiment, the process of step 400 can specifically include the following steps: The difference between the second heat conduction coefficient of the current period and the second heat conduction coefficient of the previous period is calculated, and the difference is compared with the second heat conduction coefficient of the previous period to obtain a heat conduction coefficient change rate; When the heat conduction coefficient change rate is greater than a preset change rate threshold value, it is determined that the solder melting starts, and a control signal freezing instruction is triggered; Based on the control signal freezing instruction, the first PID output signal and the third PID output signal are locked as current values and maintained for a preset welding time.

[0039] Specifically, in each control cycle, the second thermal conductivity coefficient calculated in the current cycle is recorded, and the second thermal conductivity coefficient in the current cycle is subtracted from the second thermal conductivity coefficient in the previous cycle to obtain a difference value, which is used to describe the mutation degree of the heat conduction ability per unit time. The difference value is divided by the second thermal conductivity coefficient in the previous cycle to construct a dimensionless thermal conductivity coefficient change rate, which reflects the degree of sharp change of the heat conduction characteristic of the solder joint interface during the transition from solid state to liquid state. When the thermal conductivity coefficient change rate exceeds a preset change rate threshold, for example, the change rate is greater than 0.30, it indicates that the second thermal conductivity coefficient has obviously jumped relative to the previous cycle, which is due to the solder reaching the melting point and starting to melt, and the liquid solder filling the original micro air gap, causing the contact thermal resistance of the solder joint to drop sharply, thereby improving the unit heat flow transfer efficiency. Based on this change rule, it is determined that the solder has started to melt, and a control signal freezing instruction is triggered. Based on the control signal freezing instruction, the output signal of the current first PID controller, that is, the workbench heating power, is kept at a fixed value at the freezing time, and no longer responds to the subsequent control error update; at the same time, the third PID output signal that has been subjected to current limiting modulation, that is, the actual heating signal of the iron head, is also locked to the output value at the freezing moment, maintaining the current heat power state, to provide a stable temperature environment for the solder to fully melt, flow, and wet the pads and pins. In the frozen state, the timing module starts to run, and the first PID and the third PID signal are kept in the frozen state until the preset welding time ends, for example, 5 seconds are set to ensure that the typical solder joint completes metal wetting diffusion and stable formation of liquid solder, and to avoid quality problems such as virtual welding, continuous welding or local solder condensation caused by unstable thermal field due to frequent fluctuations of the control signal. After the freezing time ends, the lock is automatically released, the PID controller resumes responding to the real-time error, and the heat flow scheduling and current limiting protection logic are restarted.

[0040] In a specific embodiment, the process of step 500 can specifically include the following steps: Calculate the cooling rate of the PCB substrate temperature, determine whether the cooling rate is within a preset cooling rate range, and obtain a cooling rate deviation state; When the cooling rate deviation state is too fast, increase the first PID output signal to raise the workbench target temperature, and when the cooling rate deviation state is too slow, decrease the first PID output signal; Collect the static voltage of the workbench, and when the static voltage of the workbench exceeds a preset static threshold, perform current limiting on the third PID output signal, and when the leakage current exceeds a preset leakage current threshold, turn off the heating.

[0041] Specifically, a cooling rate dynamic regulation mechanism based on the temperature change trend of the PCB substrate is introduced. The temperature of the PCB surface is continuously collected every second, and the instantaneous cooling rate is calculated by combining the temperature values at the previous and subsequent sampling times. The cooling rate is defined as the decrease amplitude of the PCB substrate temperature per unit time, and its value reflects the speed of the current cooling process. The cooling rate is compared with the preset ideal cooling rate interval, for example, the ideal cooling rate interval is set to 5-8°C / s, which is used to cover the cooling speed range required for uniform release of thermal stress during the typical solder solidification process. According to this, it is judged whether the current cooling rate is within the interval range. If it deviates from this range, it is marked as a cooling rate deviation state. When the cooling rate deviation state is determined to be too fast cooling, i.e. the temperature drop speed exceeds the upper limit of 8°C / s, it indicates that the heat loss is too fast, causing uneven solder shrinkage, solder joint structure rupture or internal residual stress accumulation of components. At this time, the output signal of the first PID controller is increased, and the target temperature of the workbench surface is correspondingly adjusted upwards, so that part of the heat is released again through the surface to slow down the overall cooling trend, and the heat field buffer is realized. If the cooling rate deviation state is determined to be too slow cooling, i.e. the temperature drop speed is lower than the lower limit of 5°C / s, it means that the heat retention time is too long, causing solder grain coarsening and disturbance of the solder solidification process. At this time, the output signal of the first PID controller is reduced, and the target temperature of the workbench surface is lowered, so as to speed up the heat dissipation process to restore a reasonable cooling channel. At the same time, the voltage value of the workbench surface to the ground is collected in parallel to detect the static electricity accumulation level in real time. The voltage sampling is fed back to the main control chip by the static electricity detection circuit at fixed time intervals. When the static voltage of the workbench surface exceeds the set threshold value, for example, 200V, it is determined that there is a high risk of static electricity. To avoid damage to sensitive devices caused by static discharge, the third PID output signal is subjected to current limiting processing, and the current heating control signal is attenuated to a safe output level, for example, multiplied by 0.3, so that the heating power of the iron head is maintained at a very low state to reduce the electrical field disturbance. The leakage current state is monitored by the integrated power supply protection module, and the current difference between the live wire and the zero line is continuously sampled. When the detection value exceeds 30mA and lasts for more than 50ms, the heating shutdown operation is performed, which specifically includes pulling the gate voltage of the control IGBT to the cutoff state, and simultaneously disconnecting the solid-state relay, so as to completely cut off the heating of the workbench surface and the power supply of the iron head, and the whole machine enters the forced shutdown protection state.

[0042] When the cooling rate deviation state is too fast, the first PID output signal is increased to raise the mesa target temperature; when the cooling rate deviation state is too slow, the first PID output signal is decreased. The method comprises: setting a multi-stage ladder cooling target temperature sequence, wherein the ladder cooling target temperature sequence comprises a first ladder target temperature, a second ladder target temperature and a natural cooling target temperature, and each stage of the ladder target temperature is configured with a ladder maintenance time; lowering the mesa target temperature of the first PID controller from a current preheating temperature to the first ladder target temperature, monitoring the PCB substrate temperature and calculating a first stage cooling rate, adjusting the first PID output signal when the first stage cooling rate exceeds a preset cooling rate range, and maintaining the first ladder target temperature until the ladder maintenance time ends; lowering the mesa target temperature from the first ladder target temperature to the second ladder target temperature, monitoring the PCB substrate temperature and calculating a second stage cooling rate, adjusting the first PID output signal when the second stage cooling rate exceeds the preset cooling rate range, and maintaining the second ladder target temperature until the ladder maintenance time ends; after completing the second ladder target temperature maintenance, turning off the first PID controller to enter a natural cooling stage, and continuously monitoring the cooling rate of the PCB substrate temperature to ensure that the cooling rate is always within the preset cooling rate range during the entire cooling process.

[0043] In this embodiment, before distributing the first PID output signal and the second PID output signal according to the heat conduction fusion coefficient, the following steps are further included: establishing a temperature prediction model based on a heat conduction equation, the temperature prediction model predicting an iron tip temperature evolution trajectory and a substrate temperature evolution trajectory within a future preset time window according to the first PID output signal, the second PID output signal, the heat conduction fusion coefficient and system thermal inertia parameters in a current period, the system thermal inertia parameters including a workbench thermal capacity, an iron tip thermal capacity and a heat conduction time constant; constructing a predictive optimization objective function including a tracking error term, an output smoothing term and a temperature constraint penalty term, the tracking error term being calculated according to cumulative deviations of the iron tip temperature evolution trajectory and an iron tip target temperature, the output smoothing term being calculated according to variation gradients of the first PID output signal and the second PID output signal, and the temperature constraint penalty term being calculated according to a penalty value when the substrate temperature evolution trajectory exceeds a component safety temperature range, and an incremental penalty weight being set according to an exceeding amplitude when the predicted substrate temperature exceeds the component safety temperature range; offline establishing a multi-working-condition parameter database, the multi-working-condition parameter database storing optimized parameter combinations corresponding to different heat conduction fusion coefficient intervals and different component types, the optimized parameter combinations including a prediction time window length, a control update period and a PID output limiting coefficient, and the optimized parameter combinations being obtained through multiple rounds of iteration optimization of the predictive optimization objective function by a genetic algorithm; querying a matched optimized parameter combination from the multi-working-condition parameter database according to the current heat conduction fusion coefficient and the type of the component to be repaired, performing interpolation calculation on adjacent optimized parameter combinations when the heat conduction fusion coefficient is between two stored intervals, setting the output limiting coefficient of the first PID controller and the second PID controller based on the optimized parameter combination obtained through the querying or interpolation, and performing PID output distribution adjustment according to the control update period.

[0044] The intelligent temperature control rework soldering method in the embodiments of the application is described above, and the intelligent temperature control rework soldering device in the embodiments of the application is described below. Please refer to Figure 2 An embodiment of the intelligent temperature control rework soldering device in the embodiments of the application includes: The acquisition module 11 is configured to acquire a workbench surface preheating temperature, an iron tip real-time temperature and a PCB substrate temperature, and calculate a first heat conduction coefficient between the workbench surface and the iron tip and a second heat conduction coefficient between the iron tip and a soldering point. The adjustment module 12 is configured to adjust a workbench surface target temperature based on the first heat conduction coefficient and the second heat conduction coefficient. The driving module 13 is configured to output a first PID output signal from the first PID controller to drive the workbench to heat, output a second PID output signal from the second PID controller to drive the iron tip to heat, and calculate a current margin to modulate the second PID output signal, so as to obtain a third PID output signal. The maintaining module 14 is configured to monitor the second thermal conductivity coefficient to determine the start of solder melting, freeze the first PID output signal and the third PID output signal to maintain the preset welding time; The executing module 15 is configured to control the cooling process based on the cooling rate of the PCB substrate temperature, execute current limiting or turn off the heating.

[0045] Please refer to Figure 3 , Figure 3 The structural schematic block diagram of the electronic device 300 provided by the embodiment of the present application is shown in FIG. 3. The electronic device 300 includes a processor 301 and a memory 302, and the processor 301 and the memory 302 are connected through a device bus 303. The memory 302 can include a non-volatile storage medium and an internal memory.

[0046] The non-volatile storage medium can store a computer program. The computer program includes program instructions, which, when executed by the processor 301, can cause the processor 301 to execute any of the above-mentioned intelligent temperature control repair soldering methods.

[0047] The processor 301 is configured to provide computing and control capabilities to support the operation of the entire electronic device 300.

[0048] The internal memory provides an environment for the execution of the computer program in the non-volatile storage medium. The computer program, when executed by the processor 301, can cause the processor 301 to execute any of the above-mentioned intelligent temperature control repair soldering methods.

[0049] Those skilled in the art can understand that Figure 3 The structure shown in FIG. 3 is only a block diagram of part of the structure related to the scheme of the present application, and does not constitute a limitation on the electronic device 300 related to the scheme of the present application. Specifically, the electronic device 300 can include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0050] It should be understood that the processor 301 can be a central processing unit (CPU), and the processor 301 can also be other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. Among them, the general-purpose processor can be a microprocessor or the processor can also be any conventional processor.

[0051] It should be noted that, for the convenience and brevity of description, the specific working process of the electronic device 300 described above can be referred to the corresponding process of the foregoing intelligent temperature control repair soldering method, and will not be described here.

[0052] The embodiment of the present application further provides a computer readable storage medium, which stores a computer program. The computer program is executed by one or more processors to enable the one or more processors to implement the intelligent temperature control repair soldering method provided by the embodiment of the present application.

[0053] The computer readable storage medium can be an internal storage unit of the electronic device 300, such as a hard disk or a memory of the electronic device 300. The computer readable storage medium can also be an external storage device of the electronic device 300, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc.

[0054] It should be noted that, for the convenience and brevity of description, the specific working process of the system, device and unit described above can be referred to the corresponding process in the foregoing method embodiments, and will not be described here.

[0055] The integrated unit, if realized in the form of a software function unit and sold or used as an independent product, can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application, essentially or say the part that makes contributions to the prior art or the whole or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium, and includes a number of instructions to make an electronic device (which can be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the methods described in the embodiments of the present application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and various program code storage media.

[0056] The above-described embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An intelligent temperature-controlled rework soldering method, characterized by, The method comprises the following steps: Collecting the preheating temperature of the workbench, the real-time temperature of the soldering iron head, and the temperature of the PCB substrate, calculating the first heat conduction coefficient between the workbench and the soldering iron head and the second heat conduction coefficient between the soldering iron head and the soldering point; Adjusting the target temperature of the workbench based on the first heat conduction coefficient and the second heat conduction coefficient; The first PID controller outputs a first PID output signal according to the target temperature of the workbench to drive the heating of the workbench, and the second PID controller outputs a second PID output signal to drive the heating of the soldering iron head and calculates the current margin to modulate the second PID output signal to obtain a third PID output signal; Monitoring the second heat conduction coefficient to determine the start of solder melting, and freezing the first PID output signal and the third PID output signal to maintain the preset welding time; Based on the cooling rate of the PCB substrate temperature, the target temperature of the workbench is adjusted to control the cooling process, and the heating is turned off or limited.

2. The intelligent temperature-controlled rework soldering method of claim 1, wherein, The method comprises the following steps: Collecting the preheating temperature of the workbench, the real-time temperature of the soldering iron head, and the temperature of the PCB substrate; Calculating the first heat conduction coefficient according to the first temperature difference between the real-time temperature of the soldering iron head and the preheating temperature of the workbench, the first contact thermal resistance between the workbench and the soldering iron head, and the sampling time interval; Calculating the second heat conduction coefficient according to the second temperature difference between the real-time temperature of the soldering iron head and the temperature of the PCB substrate, the second contact thermal resistance of the solder layer, and the sampling time interval.

3. The intelligent temperature-controlled rework soldering method of claim 1, wherein, The method comprises the following steps: Calculating the heat conduction fusion coefficient according to the ratio of the first heat conduction coefficient to the sum of the first heat conduction coefficient and the second heat conduction coefficient; When the heat conduction fusion coefficient is greater than a first threshold value, it is determined that the preheating temperature of the workbench is too high, and when the heat conduction fusion coefficient is less than a second threshold value, it is determined that the preheating temperature of the workbench is insufficient; Calculating the temperature adjustment amount of the workbench based on the deviation of the heat conduction fusion coefficient from the preset ideal value and the preset adjustment coefficient, and adjusting the target temperature of the workbench according to the reference temperature of the workbench and the temperature adjustment amount of the workbench.

4. The intelligent temperature-controlled rework soldering method of claim 3, wherein, The first PID controller outputs a first PID output signal according to the target temperature of the workbench to drive the heating of the workbench, and the second PID controller outputs a second PID output signal to drive the heating of the soldering iron head and calculates the current margin to modulate the second PID output signal to obtain a third PID output signal, comprising: The first PID controller calculates the first control error between the target temperature of the workbench and the preheating temperature of the workbench, and outputs a first PID output signal based on the first control error to drive the workbench to heat to the preheating temperature and stabilize; Determining the target temperature of the soldering iron head according to the type of the component to be repaired, and the second PID controller calculates the second control error between the target temperature of the soldering iron head and the real-time temperature of the soldering iron head; The second PID controller outputs a second PID output signal based on the second control error to drive the heating of the soldering iron head, monitors the heating rate of the soldering iron head, and controls the heating rate within a preset heating rate range; The first PID output signal and the second PID output signal are distributed according to the heat conduction fusion coefficient, a current margin is calculated based on a real-time heating current, a current limiting coefficient is obtained to modulate the second PID output signal, and a third PID output signal is obtained.

5. The intelligent temperature-controlled rework soldering method of claim 4, wherein, The first PID output signal and the second PID output signal are distributed according to the heat conduction fusion coefficient, a current margin is calculated based on a real-time heating current, a current limiting coefficient is obtained to modulate the second PID output signal, and a third PID output signal is obtained. When the heat conduction fusion coefficient is greater than a first threshold value, the first PID output signal is adjusted by a first proportional coefficient, and when the heat conduction fusion coefficient is less than a second threshold value, the second PID output signal is adjusted by a second proportional coefficient; A real-time heating current of the iron tip heating loop is collected, and a current margin is calculated according to the real-time heating current and a peak current threshold value determined according to the iron tip power; A current limiting coefficient is determined according to the current margin, and the second PID output signal is modulated based on the current limiting coefficient to obtain a third PID output signal.

6. The intelligent temperature-controlled rework soldering method of claim 5, wherein, The second heat conduction coefficient is monitored to determine that solder melting starts, and the first PID output signal and the third PID output signal are frozen to maintain a preset welding time, including: A difference between the second heat conduction coefficient of the current period and the second heat conduction coefficient of the previous period is calculated, and a ratio calculation is performed on the difference and the second heat conduction coefficient of the previous period to obtain a heat conduction coefficient change rate; When the heat conduction coefficient change rate is greater than a preset change rate threshold value, it is determined that solder melting starts, and a control signal freezing instruction is triggered; Based on the control signal freezing instruction, the first PID output signal and the third PID output signal are locked as current values and maintained for a preset welding time.

7. The intelligent temperature-controlled rework soldering method of claim 1, wherein, The cooling rate of the PCB substrate temperature is used to regulate the target temperature control cooling process of the table surface, and current limiting or heating shutdown is performed, including: The cooling rate of the PCB substrate temperature is calculated, and it is determined whether the cooling rate is within a preset cooling rate range to obtain a cooling rate deviation state; When the cooling rate deviation state is that the cooling is too fast, the first PID output signal is increased to increase the target temperature of the table surface, and when the cooling rate deviation state is that the cooling is too slow, the first PID output signal is decreased; The worktable surface static voltage is collected, and when the worktable surface static voltage exceeds a preset static threshold value, the third PID output signal is current limited, and when the leakage current exceeds a preset leakage current threshold value, the heating is shut down.

8. An intelligent temperature control rework soldering device, characterized in that, The intelligent temperature control repair soldering device is used to perform the intelligent temperature control repair soldering method as claimed in any one of claims 1-7, and the intelligent temperature control repair soldering device includes: A collection module is configured to collect a worktable surface preheating temperature, an iron tip real-time temperature, and a PCB substrate temperature, and calculate a first heat conduction coefficient between the table surface and the iron tip and a second heat conduction coefficient between the iron tip and a solder joint. An adjustment module is configured to adjust a target temperature of the table surface based on the first heat conduction coefficient and the second heat conduction coefficient. The driving module is configured to drive the workbench to heat according to a first PID output signal output by a first PID controller based on the workbench target temperature, drive the iron tip to heat according to a second PID output signal output by a second PID controller, and calculate a current margin to modulate the second PID output signal to obtain a third PID output signal; The maintaining module is configured to monitor the second heat conduction coefficient to determine the start of the solder melting, and freeze the first PID output signal and the third PID output signal to maintain a preset welding time; The executing module is configured to control the cooling process based on the cooling rate of the PCB substrate temperature, and execute current limiting or turn off the heating.

9. An electronic device, comprising: The electronic device comprises a memory and at least one processor, and the memory stores instructions. The at least one processor invokes the instructions in the memory to enable the electronic device to execute the intelligent temperature control repair soldering method according to any one of claims 1-7.

10. A computer-readable storage medium having stored thereon instructions, the instructions comprising, The instructions are executed by the processor to implement the intelligent temperature control repair soldering method according to any one of claims 1-7.

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