Temperature prediction method, device and equipment for wave soldering

Abstract

The invention discloses a temperature prediction method, device and equipment for wave soldering, and relates to the technical field of electronic manufacturing, and the method comprises the steps: obtaining a thermal simulation model of a to-be-processed accessory; obtaining a digital twinborn model of the wave soldering process; wherein the digital twin model comprises a preheating stage in a wave soldering process and a thermal boundary condition of a wave soldering stage; performing wave-soldering transient temperature field simulation on the thermal simulation model by using a digital twinborn model, and performing calculation by using a solver to obtain temperature data of a preset temperature monitoring point in a simulation process; the temperature of the position needing to be monitored can be predicted in the whole preheating and welding process of wave soldering, the heating condition of the device can be known before physical furnace passing, a sensor does not need to be physically embedded, the manpower and material resource cost is reduced, and therefore pre-judgment of the over-temperature risk can be achieved; and the condition of device damage caused by over-temperature in batch production is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic manufacturing, in particular to a temperature prediction method, device and equipment for wave soldering. BACKGROUND

[0002] In the electronic manufacturing industry, wave soldering is the core soldering process of PTH (Plated Through Hole, insert type through hole) devices, and its temperature control directly affects the reliability of the devices. In related technologies, temperature monitoring during the wave soldering process is all in the form of post-monitoring, such as relying on physical experiments to obtain temperature parameters; using wave soldering equipment to record the furnace temperature curve, but it is difficult to reflect the actual temperature of the device; using embedded thermocouples for actual measurement, but it needs to pass through the furnace with the PCB (Printed Circuit Board), the position is fixed and the internal temperature of the device cannot be captured; using an infrared thermal imager to measure the surface instantaneous temperature. The above temperature monitoring methods are difficult to predict the risk of over-temperature (especially for small size devices), which makes it easy to cause device damage due to over-temperature during mass production, and there are problems such as material consumption, production line occupation, labor and material costs, etc.

[0003] Therefore, how to realize temperature prediction in the wave soldering process that breaks through the physical limit, reduce the labor and material costs, so that the device heating condition can be known without passing through the furnace before production, thereby realizing the prediction of the over-temperature risk and reducing the device damage due to over-temperature during mass production, is a problem that needs to be solved urgently. SUMMARY

[0004] The purpose of the present application is to provide a temperature prediction method, device and equipment for wave soldering, to realize temperature prediction in the wave soldering process that breaks through the physical limit, and reduce the labor and material costs.

[0005] To solve the above technical problems, the present application provides a temperature prediction method for wave soldering, comprising:

[0006] obtaining a thermal simulation model of a to-be-processed accessory; wherein the thermal simulation model comprises a three-dimensional model of a printed circuit board, a jig and a to-be-soldered device, and material thermal physical property parameters;

[0007] obtaining a digital twin model of a wave soldering process; wherein the digital twin model comprises thermal boundary conditions of a preheating stage and a wave soldering stage in the wave soldering process;

[0008] using the digital twin model to perform transient temperature field simulation of the wave soldering on the thermal simulation model, and using a solver to calculate temperature data of a preset temperature monitoring point in the simulation process; wherein the preset temperature monitoring point comprises a temperature monitoring point in the three-dimensional model of the printed circuit board and / or the to-be-soldered device.

[0009] On the other hand, obtaining the thermal simulation model of the part to be processed includes:

[0010] Obtain a three-dimensional model of the assembly; wherein, the three-dimensional model of the assembly is a three-dimensional model obtained by combining the three-dimensional models of the printed circuit board, the fixture and the device to be soldered;

[0011] Assign material thermal property parameters to each component in the 3D model of the assembly, and perform mesh subdivision to obtain the thermal simulation model.

[0012] On the other hand, obtaining the 3D model of the assembly includes:

[0013] Construct a three-dimensional model of the printed circuit board; wherein the three-dimensional model of the printed circuit board includes the flame retardant material grade and copper traces;

[0014] Construct a three-dimensional model of the fixture; wherein the three-dimensional model of the fixture includes a bottom opening;

[0015] Construct a three-dimensional model of the device to be soldered; wherein the three-dimensional model of the device to be soldered includes an internal core layer, a flow layer, pins, and a shell;

[0016] Based on the preset distance between the bottom of each of the components to be soldered and the printed circuit board, the three-dimensional models of the printed circuit board, the fixture, and the components to be soldered are combined to obtain the three-dimensional model of the assembly.

[0017] On the other hand, the calculation of temperature data at the preset temperature monitoring point during the simulation process using the solver includes:

[0018] Using the solver, the Navier-Stokes equations and energy equations are solved by the finite volume method to obtain the temperature data corresponding to each of the preset temperature monitoring points during the simulation process.

[0019] On the other hand, the preset temperature monitoring points include pin monitoring points and / or preset test points; wherein, the pin monitoring points are set at surface pins in the three-dimensional model of the printed circuit board, and the preset test points are set at given test point positions in the three-dimensional model of the device to be soldered.

[0020] On the other hand, the process of constructing the thermal boundary conditions during the preheating stage includes:

[0021] Establish the correspondence between the conveyor belt speed and the heating time in the preheating stage;

[0022] The target ambient temperature is obtained, and a coupled model of hot air convection and infrared radiation is constructed; wherein the coupled model of hot air convection and infrared radiation includes hot air flow rate and target thermal radiation model.

[0023] On the other hand, the hot air flow rate is 2 L / s, and the target thermal radiation model is the S2S thermal radiation model.

[0024] On the other hand, the process of constructing the thermal boundary conditions in the wave soldering stage includes:

[0025] The temperature field after the preheating stage is completed is used as the initial condition for the wave soldering stage.

[0026] Establish a correspondence between the heating time in the preheating stage and the solder spraying time in the wave soldering stage; wherein, the solder spraying time includes the first wave solder spraying time and the second wave solder spraying time, and the sum of the first wave solder spraying time and the second wave solder spraying time is less than 10 seconds;

[0027] Establish the heat flux density equation at the solder-pin interface; wherein, the heat flux density equation is: ; Solder temperature For device temperature, For contact thermal resistance, For pin thermal resistance, The convective heat transfer coefficient is... For surface emissivity, It is the Stefan-Boltzmann constant; Heat flux density;

[0028] A contact thermal resistance correction factor is established to adjust the contact thermal resistance; wherein, the contact thermal resistance correction factor is... , , and All are preset fitting coefficients. For conveyor belt speed, For welding time;

[0029] Establish the correspondence between the conveyor belt speed and the solder temperature.

[0030] The present invention also provides a temperature prediction device for wave soldering, comprising:

[0031] The first acquisition module is used to acquire the thermal simulation model of the part to be processed; wherein, the thermal simulation model includes a three-dimensional model of the printed circuit board, the fixture and the device to be soldered, as well as the material thermal property parameters;

[0032] The second acquisition module is used to acquire a digital twin model of the wave soldering process; wherein, the digital twin model includes the preheating stage and the thermal boundary conditions of the wave soldering stage in the wave soldering process;

[0033] The simulation prediction module is used to simulate the transient temperature field of wave soldering on the thermal simulation model using the digital twin model, and to calculate the temperature data of the preset temperature monitoring points during the simulation process using a solver; wherein, the preset temperature monitoring points include temperature monitoring points in the three-dimensional model of the printed circuit board and / or the device to be soldered.

[0034] The present invention also provides a temperature prediction device for wave soldering, comprising:

[0035] Memory, used to store computer programs;

[0036] A processor is used to implement the steps of the wave soldering temperature prediction method described above when executing the computer program.

[0037] The present invention provides a temperature prediction method for wave soldering, comprising: acquiring a thermal simulation model of the component to be processed; wherein the thermal simulation model includes a three-dimensional model of a printed circuit board, a fixture, and the component to be soldered, as well as material thermal property parameters; acquiring a digital twin model of the wave soldering process; wherein the digital twin model includes the thermal boundary conditions of the preheating stage and the wave soldering stage in the wave soldering process; using the digital twin model to simulate the transient temperature field of wave soldering on the thermal simulation model, and using a solver to calculate the temperature data of a preset temperature monitoring point during the simulation process; wherein the preset temperature monitoring point includes temperature monitoring points in the three-dimensional model of the printed circuit board and / or the component to be soldered.

[0038] As can be seen, this invention utilizes a digital twin model to simulate the transient temperature field of wave soldering using a thermal simulation model, and uses a solver to calculate the temperature data of preset temperature monitoring points during the simulation process. This allows for the prediction of the temperature at the required monitoring locations throughout the preheating and soldering process of wave soldering, enabling understanding of the device's heating status before physical reflow. It eliminates the need for physically embedded sensors, reducing manpower and material costs, and thus enabling the prediction of overheating risks, reducing device damage due to overheating during mass production. Furthermore, this invention also provides a wave soldering temperature prediction device and equipment, which also possesses the aforementioned beneficial effects. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0040] Figure 1 A flowchart of a wave soldering temperature prediction method provided in an embodiment of the present invention;

[0041] Figure 2 This is a schematic flowchart of another wave soldering temperature prediction method provided in an embodiment of the present invention;

[0042] Figure 3 This is a schematic diagram of the model structure of a thermal simulation model provided in an embodiment of the present invention;

[0043] Figure 4 This is a diagram illustrating a temperature monitoring location on a PCB, provided as an embodiment of the present invention.

[0044] Figure 5 This is a diagram illustrating the temperature monitoring location on an R76TI2220SE40J capacitor, provided as an embodiment of the present invention.

[0045] Figure 6 This is a diagram illustrating a measured wave soldering furnace temperature profile provided in an embodiment of the present invention.

[0046] Figure 7 This is a diagram illustrating the comparison between measured and simulated values ​​for the wave soldering stage provided in an embodiment of the present invention.

[0047] Figure 8 This is a diagram illustrating the temperature simulation results on a PCB during the preheating stage, as provided in an embodiment of the present invention.

[0048] Figure 9 This is a diagram illustrating the temperature simulation results on capacitor X during the preheating stage, as provided in an embodiment of the present invention.

[0049] Figure 10 This is a diagram illustrating the second-level simulated temperature values ​​of a temperature monitoring point on a PCB under a preheating chain speed of 70 cm / min, provided by an embodiment of the present invention.

[0050] Figure 11 This is a diagram illustrating the temperature simulation results on a PCB during the wave soldering stage, as provided in an embodiment of the present invention.

[0051] Figure 12 This is a diagram illustrating the temperature simulation results (without leads) on an X capacitor during the wave soldering stage, as provided in an embodiment of the present invention.

[0052] Figure 13 This is a diagram illustrating a comparison table of measured and simulated values ​​during the preheating stage provided in an embodiment of the present invention.

[0053] Figure 14 This is a diagram illustrating a comparison table of simulation and actual measurements of wave soldering stages provided in an embodiment of the present invention.

[0054] Figure 15 This is a structural block diagram of a wave soldering temperature prediction device provided in an embodiment of the present invention;

[0055] Figure 16 This is a schematic diagram of the structure of a wave soldering temperature prediction device provided in an embodiment of the present invention. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] Please refer to Figure 1 , Figure 1 A flowchart illustrating a wave soldering temperature prediction method provided in an embodiment of the present invention. The method may include:

[0058] Step 101: Obtain the thermal simulation model of the part to be processed; wherein, the thermal simulation model includes the three-dimensional model of the printed circuit board, the fixture and the device to be soldered, as well as the material thermal property parameters.

[0059] It is understood that the component to be processed in this embodiment can be an integral component to be processed in the wave soldering process, that is, an integral component that enters the wave soldering process in related technologies, such as an assembly composed of a printed circuit board, a fixture, and the component to be soldered. The thermal simulation model in this embodiment (e.g. Figure 2 The multi-scale thermal simulation model in the model can be used as a model for thermal simulation (i.e. transient temperature field simulation) of the parts to be processed. By setting up the thermal simulation model of the parts to be processed, multi-scale thermal-structure coupled modeling can be achieved, breaking through the limitations of single-point temperature simulation. It can realize multi-scale heat conduction modeling from the device level (mm level) to the board level (cm level), thereby accurately predicting the internal temperature gradient of the device and providing data support for the thermal failure analysis of small capacitors.

[0060] Correspondingly, the specific content of the thermal simulation model for the parts to be processed in this step can be set by the designer according to the practical scenario and user needs. For example, the thermal simulation model can include the three-dimensional model of the printed circuit board (PCB), fixture, and device to be soldered (such as PTH device), as well as the material thermal properties parameters of each component in the three-dimensional model (such as thermal conductivity, specific heat capacity, and density); it can also include the three-dimensional model mesh subdivision information, such as subdividing the three-dimensional model of the printed circuit board, fixture, and device to be soldered (or the printed circuit board and device to be soldered) into a mesh (e.g. Figure 2 (Grid division in the example). This embodiment does not impose any limitations on this.

[0061] It should be noted that the specific method for obtaining the thermal simulation model of the part to be processed in this step can be set by the designer according to the practical scenario and user needs. For example, this step can directly receive or read the thermal simulation model of the part to be processed. This step can also create a thermal simulation model of the part to be processed. For example, this step can include obtaining a 3D model of the assembly; wherein, the 3D model of the assembly is a 3D model obtained by combining the 3D models of the printed circuit board, fixture, and the device to be soldered; and assigning material thermophysical parameters (such as...) to each component in the 3D model of the assembly. Figure 2 The process of assigning material values ​​in the model (and then subdividing the mesh) is used to obtain the thermal simulation model. This embodiment does not impose any limitations on this.

[0062] Correspondingly, the process of obtaining the 3D model of the assembly described above can be set by the designer, such as directly receiving or reading the 3D model of the assembly; or the 3D model of the assembly can be constructed, such as constructing a 3D model of a printed circuit board (PCB); wherein the 3D model of the PCB includes the flame retardant material grade and copper traces; constructing a 3D model of a fixture; wherein the 3D model of the fixture includes a bottom opening; constructing a 3D model of the device to be soldered; wherein the 3D model of the device to be soldered includes an internal core layer, a flow layer, pins, and a shell; and combining the 3D models of the PCB, fixture, and device to be soldered according to the preset distance between the bottom of each device to be soldered and the PCB to obtain the 3D model of the assembly.

[0063] Correspondingly, the process of assigning material thermal property parameters to each component in the 3D model of the assembly and subdividing the mesh to obtain the thermal simulation model can be achieved using thermal simulation software. For example, the 3D model of the assembly is input into the thermal simulation software; using the thermal simulation software, material thermal property parameters are assigned to each component in the 3D model of the assembly, and the 3D model of the assembly is subdivided into a mesh to obtain the thermal simulation model of the part to be processed.

[0064] For example, in this step, a 3D model can be created for a 4-layer test printed circuit board with dimensions l1×w1×h1=90mm×60mm×0.9mm, including FR4 (a code for a flame-retardant material grade) and copper traces; a 3D model for a fixture with dimensions l2×w2×h2=419.5mm×389.5mm×8mm and including a bottom opening (to facilitate solder spraying upwards to interconnect device leads and the PCB); and a 3D model for a standard X capacitor with part number R76TI2220SE40J, including an internal core layer, flow layer, leads, and shell. After assembling the above 3D models into an assembly (the distance from the bottom of the X capacitor's shell to the PCB is d=0.7mm), as shown... Figure 3As shown, the thermal simulation software is imported. The thermal simulation software can assign material thermal property parameters to each component in the 3D model of the assembly. For example, based on the Celsius EC Solver platform (a tool for analyzing electronic heat dissipation), differentiated settings of thermal property parameters for multiple materials can be achieved. Since this embodiment is a real-time monitoring transient thermal simulation, material thermal property parameters such as thermal conductivity (W / m·K), specific heat capacity (J / kg·℃), and density (kg / m³) can be assigned to each layer of the model. The 3D model is then meshed; for example, after mesh subdivision, the mesh accuracy in key areas can reach 0.1 mm.

[0065] Step 102: Obtain a digital twin model of the wave soldering process; wherein, the digital twin model includes the preheating stage and the thermal boundary conditions of the wave soldering stage in the wave soldering process.

[0066] It is understood that the digital twin model in this embodiment (such as...) Figure 2 The mathematical twin model of wave soldering process can be a digital twin model of the wave soldering process (i.e., the preheating stage + the wave soldering stage).

[0067] Correspondingly, the specific method for obtaining the digital twin model of the wave soldering process in this step can be set by the designer according to the practical scenario and user needs. For example, this step can directly receive or read the digital twin model of the wave soldering process. This step can also create the digital twin model of the wave soldering process. For example, this step can include the construction process of the thermal boundary conditions for the preheating stage and the wave soldering stage. For example, the construction process of the thermal boundary conditions for the preheating stage can include: constructing the correspondence between the conveyor belt speed and the heating time in the preheating stage; obtaining the target ambient temperature, and constructing a hot air convection and infrared radiation coupling model; wherein, the hot air convection and infrared radiation coupling model includes the hot air flow rate and the target thermal radiation model. For example, it can be done by using... This study establishes the correlation between conveyor belt speed and preheating time, quantifying "conveyor belt speed (v, unit: cm / min)" as an acceptable input for thermal simulation—heating time. (Unit: s), to realize the digital mapping of industrial parameters, thereby corresponding to the preset furnace temperature curve parameters (such as the furnace temperature curve parameters provided by the supplier), to realize the two-way mapping of the kinematic and thermodynamic parameters of the transmission system, L is the length of the preheating zone, unit: cm; set the ambient temperature (i.e. the target ambient temperature) to TA=220℃, and quantize the hot air heating temperature unit and infrared heating unit of the preheating stage, as the input parameters for the thermal simulation to construct the hot air convection and infrared radiation coupling model, such as after multiple NS (Navier-Stokes) equations and simulation and measurement calibration, the hot air flow rate Q v It can be set to Q v=2L / s (liters per second), hot air is simultaneously input from the bottom of the fixture and the top of the device (simulating a scenario of uniform preheating from top to bottom in a real physical environment), the thermal radiation module is turned on, and the S2S thermal radiation model (i.e., the target thermal radiation model) is selected. That is to say, the above hot air flow rate can be 2L / s, and the target thermal radiation model can be the S2S thermal radiation model.

[0068] Accordingly, the process of constructing the thermal boundary conditions for the wave soldering stage may include: using the temperature field after the preheating stage as the initial condition for the wave soldering stage; establishing the correspondence between the heating time of the preheating stage and the solder spraying time of the wave soldering stage; wherein, the solder spraying time includes the first wave solder spraying time and the second wave solder spraying time, and the sum of the first wave solder spraying time and the second wave solder spraying time is less than 10 seconds; establishing the heat flux density equation at the solder-pin interface; wherein, the heat flux density equation is... ; The solder temperature is (°C). The device temperature is in °C. The contact thermal resistance is (W / m·K). For pin thermal resistance, The convective heat transfer coefficient is... For surface emissivity, It is the Stefan-Boltzmann constant; Let the heat flux density be ; establish a contact thermal resistance correction factor to adjust the contact thermal resistance; where the contact thermal resistance correction factor is . , , and All are preset fitting coefficients. For conveyor belt speed, For welding time; establish the correspondence between conveyor belt speed and solder temperature.

[0069] For example, the temperature field results of each component after preheating at the end of the preheating stage can be coupled into the boundary condition construction of the wave soldering stage and used as the initial temperature of each component. Since the solder is sprayed twice in the wave soldering stage, the first wave of solder spraying lasts about 2-4 seconds and the second wave of solder spraying lasts 3-6 seconds, with a total duration of no more than 10 seconds, the corresponding solder spraying time can be determined by establishing a correspondence between the heating time in the preheating stage and the solder spraying time in the wave soldering stage, based on the input of the heating time converted from the chain speed.

[0070] Establish the heat flux density equation at the solder-pin interface: Among them, the pin thermal resistance ( Contact thermal resistance ( ) can be calculated from the parameters given in the datasheet. The following process can be used to derive: According to the law of conservation of energy, the device's contact time with solder (t)时 The heat Q absorbed internally w =m·C·(Tc-Tpre;where Tc can be the temperature at the preset temperature monitoring point after soldering, Tpre can be the initial temperature after preheating, m is the mass of the device (kg), and c is the specific heat capacity of the device (J / kg·K); according to the definition of heat flux density, q=Q w / A·t, where A is the cross-sectional area of ​​the pin and t is the temperature at which the solder contacts; from this, the contact thermal resistance can be derived ( ).

[0071] Introducing a correction factor for the contact thermal resistance between the solder and the PCB interface: The contact thermal resistance is dynamically adjusted based on the welding time, temperature, and chain speed. Specifically, a faster chain speed (v) results in a longer contact time with the solder (t). 时 The heat flux is reduced, thus requiring a reduction in Rc to increase the heat flow. The wave soldering stage is mainly based on heat conduction. Since the focus is on the highest temperature and location of the device during the soldering process after preheating, this stage does not involve the solder paste changing from a molten state to a solidified state, and therefore does not involve a phase change. The material parameters of the molten solder can be assigned to the solder amount SAC305.

[0072] Setting the solder temperature: Based on the measured solder temperature trend and the principle of heat transfer, it can be found that the faster the conveyor belt speed, the shorter the heating time, and the less heat is transferred from the solder to the pin. Therefore, the solder temperature can be dynamically assigned by utilizing the established correspondence between the conveyor belt speed and the solder temperature.

[0073] In other words, this step can establish a nonlinear mapping relationship between conveyor belt speed, preheating temperature, and welding time, enabling dynamic adjustment of process parameters and ensuring that the maximum temperature prediction error is less than 4%. Furthermore, considering the combined heating effect of hot air convection and infrared radiation, the S2S radiation model is introduced to calculate the angle coefficient, achieving an accurate simulation of the temperature difference between the upper and lower surfaces of the PCB, resulting in a maximum temperature prediction error of only about 6.3% during the preheating stage.

[0074] Step 103: Use a digital twin model to simulate the transient temperature field of wave soldering on the thermal simulation model, and use a solver to calculate the temperature data of the preset temperature monitoring points during the simulation process; wherein, the preset temperature monitoring points include the temperature monitoring points in the three-dimensional model of the printed circuit board and / or the device to be soldered.

[0075] Understandably, in this step, a digital twin model can be used to simulate the transient temperature field of wave soldering (preheating + welding) on ​​the thermal simulation model, so as to use a solver to calculate the temperature data of the preset temperature monitoring points during the simulation process and realize the temperature prediction of each preset temperature monitoring point.

[0076] Correspondingly, this step may also include the process of obtaining preset temperature monitoring points. The specific number and location of the preset temperature monitoring points in this embodiment can be set by the designer. For example, the preset temperature monitoring points may include pin monitoring points and / or preset test points; wherein, pin monitoring points are set at surface pins in the 3D model of the printed circuit board, and preset test points are set at given test point locations in the 3D model of the device to be soldered. For example, the number of preset temperature monitoring points can be two, with one preset temperature monitoring point set at a surface pin in the 3D model of the PCB, such as... Figure 4 The test point in the model has an X and Y coordinate accuracy of ±0.01mm; another preset temperature monitoring point is set at a preset test point on the 3D model of the device to be soldered, such as... Figure 5 Set the corresponding temperature monitoring point based on the sensor position of the R76TI2220SE40J capacitor provided by the supplier.

[0077] It should be noted that the specific method used in this step to calculate the temperature data of the preset temperature monitoring points during the simulation process can be set by the designer according to the practical scenario and user needs. For example, the solver can be used to solve the Navier-Stokes (NS) equations and energy equations using the finite volume method (FVM) to obtain the temperature data of each preset temperature monitoring point during the simulation process. For instance, the solver can use FVM (finite volume method) to solve the NS equations (based on the law of conservation of momentum) and energy equations (based on the law of conservation of energy), and the time step can be set. =0.5s, convergence residual The temperature distribution (i.e., temperature data) of each preset temperature monitoring point during the simulation process can be obtained by distribution calculation; alternatively, the temperature data of each preset temperature monitoring point during the simulation process can be calculated and solved using a solver in other ways. This embodiment does not impose any restrictions on this.

[0078] Furthermore, in this embodiment, after obtaining the temperature data of the preset temperature monitoring points during the simulation process, the temperature data of each preset temperature monitoring point can be analyzed to obtain temperature analysis information. For example, the temperature analysis information may include the highest temperature value and occurrence time of each preset temperature monitoring point, thereby realizing the simulation analysis of the highest temperature value, occurrence time and specific location of each part of the PTH device and PCB.

[0079] Correspondingly, in this embodiment, after obtaining the temperature data of the preset temperature monitoring points during the simulation process, the temperature data of each preset temperature monitoring point can be used to predict the risk of overheating in wave soldering in advance. For example, the temperature data of each preset temperature monitoring point can be compared with its corresponding overheating risk threshold to determine the target temperature data of the target temperature monitoring point. The target temperature monitoring point is a preset temperature monitoring point in which the temperature data contains a temperature value greater than the corresponding overheating risk threshold. The target temperature data includes temperature values ​​greater than the corresponding overheating risk threshold. Based on the target temperature monitoring point and / or the target temperature data, overheating risk alarm information is output.

[0080] For example, a thermocouple is embedded on the side of the R76TI2220SE40J capacitor casing. After the entire board passes through the furnace, the furnace temperature curve is obtained as follows: Figure 6 As shown, extract the required measured parameters. See details below. Figure 7 The temperature field distribution cloud map of the device and PCB during the preheating stage is shown below. Figure 8 and Figure 9 As shown; the temperature distribution on a second-level scale is as follows Figure 10 The example shown illustrates the second-level temperature distribution at a PCB monitoring point under a preheating chain speed of 70 cm / min. During the preheating phase, a comparison of simulation and measured data shows that the temperature prediction error on the device is ≤6.31%, and the temperature prediction error at the monitoring point on the PCB is ≤3.46%. See details... Figure 13 .

[0081] It should be noted that in the physical experiment, the core control objective during the preheating stage is to ensure that the PCB temperature is maintained within the process range of 100℃ to 150℃. Since the real-time PCB temperature may fluctuate in actual production (e.g., locally higher temperatures), the equipment will automatically adjust the hot air flow or heating unit output power through a PID dynamic control mechanism to keep the temperature stable within the target range. Therefore, even under the same chain speed, the measured temperature during the preheating stage is not a fixed value, but rather dynamically changes within a specific range. To simplify the simulation calibration process, this embodiment uses the average value of the measured preheating temperatures at the same chain speed as the calibration benchmark for the simulation model.

[0082] Correspondingly, the temperature field distribution cloud map of the device and PCB during the wave soldering stage is as follows: Figure 11 and Figure 12 As shown. By optimizing simulation parameters using the Design of Experiments (DOE) method and comparing simulation and measured data during the soldering stage, the temperature prediction error on the device can be ≤3.62%, and the temperature prediction error on the PCB can be ≤3.44%. See details. Figure 14 ; Figure 14The measured data in group 4 of the table do not conform to the common sense that the slower the chain speed, the more heat is generated. Considering that the measurement error is the cause, this group of data is excluded from the comparison. The error of the remaining 8 groups is less than 3.44%.

[0083] In this embodiment, the present invention uses a digital twin model to simulate the transient temperature field of wave soldering on a thermal simulation model, and uses a solver to calculate the temperature data of the preset temperature monitoring point during the simulation process. This allows for the prediction of the temperature at the required monitoring location throughout the preheating and soldering process of wave soldering, enabling the understanding of the device's heating status before physical reflow. It eliminates the need for physically embedded sensors, reducing manpower and material costs, thereby enabling the prediction of overheating risks and reducing device damage due to overheating during mass production.

[0084] Corresponding to the above method embodiments, this invention also provides a wave soldering temperature prediction device. The wave soldering temperature prediction device described below and the wave soldering temperature prediction method described above can be referred to each other.

[0085] Please refer to Figure 15 , Figure 15 This is a structural block diagram of a wave soldering temperature prediction device provided in an embodiment of the present invention. The device may include:

[0086] The first acquisition module 10 is used to acquire the thermal simulation model of the part to be processed; wherein, the thermal simulation model includes a three-dimensional model of the printed circuit board, the fixture and the device to be soldered, as well as the material thermal property parameters;

[0087] The second acquisition module 20 is used to acquire a digital twin model of the wave soldering process; wherein, the digital twin model includes the preheating stage and the thermal boundary conditions of the wave soldering stage in the wave soldering process.

[0088] The simulation prediction module 30 is used to simulate the transient temperature field of wave soldering on the thermal simulation model using a digital twin model, and to calculate the temperature data of the preset temperature monitoring points during the simulation process using a solver; wherein, the preset temperature monitoring points include temperature monitoring points in the three-dimensional model of the printed circuit board and / or the device to be soldered.

[0089] In some embodiments, the first acquisition module 10 may include:

[0090] The model acquisition submodule is used to acquire the 3D model of the assembly; the 3D model of the assembly is a combination of the 3D models of the printed circuit board, the fixture and the device to be soldered.

[0091] The material assignment submodule is used to assign material thermal property parameters to each component in the 3D model of the assembly and to perform mesh subdivision to obtain a thermal simulation model.

[0092] In some embodiments, the model acquisition submodule may include:

[0093] The first building unit is used to build a three-dimensional model of the printed circuit board; wherein, the three-dimensional model of the printed circuit board includes the flame retardant material grade and copper traces;

[0094] The second building unit is used to build a three-dimensional model of the fixture; wherein, the three-dimensional model of the fixture includes a bottom opening;

[0095] The third building unit is used to build a three-dimensional model of the device to be soldered; wherein, the three-dimensional model of the device to be soldered includes an internal core layer, a flow layer, pins, and a shell;

[0096] The model assembly unit is used to combine the three-dimensional models of the printed circuit board, the fixture, and the components to be soldered according to the preset distance between the bottom of each component and the printed circuit board, so as to obtain the three-dimensional model of the assembly.

[0097] In some embodiments, the simulation prediction module 30 may include:

[0098] The solver submodule is used to solve the Navier-Stokes equations and energy equations using the solver and the finite volume method, and to obtain the temperature data of each preset temperature monitoring point during the simulation process.

[0099] In some embodiments, the preset temperature monitoring point includes a pin monitoring point and / or a preset test point; wherein the pin monitoring point is set at the surface pin in the three-dimensional model of the printed circuit board, and the preset test point is set at a given test point position in the three-dimensional model of the device to be soldered.

[0100] In some embodiments, the second acquisition module 20 may include a first construction submodule for constructing the thermal boundary conditions during the preheating stage; the first construction submodule may include:

[0101] The first relationship construction unit is used to construct the correspondence between the conveyor belt speed and the heating time in the preheating stage;

[0102] The model building unit is used to obtain the target ambient temperature and build a coupled model of hot air convection and infrared radiation; the coupled model of hot air convection and infrared radiation includes hot air flow rate and target thermal radiation model.

[0103] In some embodiments, the hot air flow rate is 2 L / s, and the target thermal radiation model is the S2S thermal radiation model.

[0104] In some embodiments, the second acquisition module 20 may include a second construction submodule for constructing thermal boundary conditions for the wave soldering stage; the second construction submodule may include:

[0105] An initial determination unit is used to take the temperature field after the preheating stage ends as the initial condition for the wave soldering stage.

[0106] The second relationship building unit is used to establish the correspondence between the heating time in the preheating stage and the solder spraying time in the wave soldering stage; wherein, the solder spraying time includes the first wave solder spraying time and the second wave solder spraying time, and the sum of the first wave solder spraying time and the second wave solder spraying time is less than 10 seconds;

[0107] The equation-setting unit is used to establish the heat flux density equation at the solder-pin interface; where the heat flux density equation is: ; Solder temperature For device temperature, For contact thermal resistance, For pin thermal resistance, The convective heat transfer coefficient is... For surface emissivity, It is the Stefan-Boltzmann constant; Heat flux density;

[0108] A correction unit is used to establish a contact thermal resistance correction coefficient, which is then used to adjust the contact thermal resistance; wherein, the contact thermal resistance correction coefficient is... , , and All are preset fitting coefficients. For conveyor belt speed, For welding time;

[0109] The third relationship building unit is used to establish the correspondence between the conveyor belt speed and the solder temperature.

[0110] In this embodiment, the present invention uses a digital twin model to simulate the transient temperature field of wave soldering using a simulation prediction module 30, and uses a solver to calculate the temperature data of the preset temperature monitoring point during the simulation process. This allows for the prediction of the temperature at the required monitoring location throughout the preheating and soldering process of wave soldering, enabling the understanding of the device's heating status before physical reflow. It eliminates the need for physically embedded sensors, reducing manpower and material costs, thereby enabling the prediction of overheating risks and reducing device damage due to overheating during mass production.

[0111] Corresponding to the above method embodiments, this invention also provides a wave soldering temperature prediction device. The wave soldering temperature prediction device described below and the wave soldering temperature prediction method described above can be referred to each other.

[0112] Please refer to Figure 16 , Figure 16This is a schematic diagram of a wave soldering temperature prediction device provided in an embodiment of the present invention. The device may include:

[0113] Memory D1 is used to store computer programs;

[0114] Processor D2 is used to implement the steps of the wave soldering temperature prediction method provided in the above method embodiments when executing a computer program.

[0115] The temperature prediction device for wave soldering provided in this embodiment can specifically be a host device or a server.

[0116] Corresponding to the above method embodiments, this invention also provides a computer program product. The computer program product described below can be referred to in conjunction with the wave soldering temperature prediction method described above.

[0117] A computer program product includes a computer program / instructions that, when executed by a processor, implement the steps of the wave soldering temperature prediction method provided in the above-described method embodiments.

[0118] Corresponding to the above method embodiments, this invention also provides a computer-readable storage medium. The computer-readable storage medium described below and the wave soldering temperature prediction method described above can be referred to each other.

[0119] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the wave soldering temperature prediction method provided in the above-described method embodiments.

[0120] The computer-readable storage medium can specifically be a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk, or any other readable storage medium capable of storing program code.

[0121] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatuses, devices, computer-readable storage media, and computer program products disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant parts can be referred to the method section.

[0122] The above provides a detailed description of the wave soldering temperature prediction method, apparatus, and equipment provided by this invention. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make various improvements and modifications to this invention without departing from its principles, and these improvements and modifications also fall within the protection scope of this invention.

Claims

1. A method for predicting the temperature of wave soldering, characterized in that, include: Obtain a thermal simulation model of the part to be processed; wherein, the thermal simulation model includes a three-dimensional model of the printed circuit board, the fixture and the device to be soldered, as well as the material thermal property parameters; Obtain a digital twin model of the wave soldering process; wherein the digital twin model includes the preheating stage and the thermal boundary conditions of the wave soldering stage in the wave soldering process; The transient temperature field of wave soldering is simulated on the thermal simulation model using the digital twin model, and the temperature data of the preset temperature monitoring points during the simulation process is calculated using a solver; wherein, the preset temperature monitoring points include temperature monitoring points in the three-dimensional model of the printed circuit board and / or the device to be soldered.

2. The wave soldering temperature prediction method according to claim 1, characterized in that, The process of obtaining the thermal simulation model of the part to be processed includes: Obtain a three-dimensional model of the assembly; wherein, the three-dimensional model of the assembly is a three-dimensional model obtained by combining the three-dimensional models of the printed circuit board, the fixture and the device to be soldered; Assign material thermal property parameters to each component in the 3D model of the assembly, and perform mesh subdivision to obtain the thermal simulation model.

3. The wave soldering temperature prediction method according to claim 2, characterized in that, The process of obtaining the 3D model of the assembly includes: Construct a three-dimensional model of the printed circuit board; wherein the three-dimensional model of the printed circuit board includes the flame retardant material grade and copper traces; Construct a three-dimensional model of the fixture; wherein the three-dimensional model of the fixture includes a bottom opening; Construct a three-dimensional model of the device to be soldered; wherein the three-dimensional model of the device to be soldered includes an internal core layer, a flow layer, pins, and a shell; Based on the preset distance between the bottom of each of the components to be soldered and the printed circuit board, the three-dimensional models of the printed circuit board, the fixture, and the components to be soldered are combined to obtain the three-dimensional model of the assembly.

4. The wave soldering temperature prediction method according to claim 1, characterized in that, The temperature data of the preset temperature monitoring point during the simulation process, calculated using the solver, includes: Using the solver, the Navier-Stokes equations and energy equations are solved by the finite volume method to obtain the temperature data corresponding to each of the preset temperature monitoring points during the simulation process.

5. The wave soldering temperature prediction method according to claim 1, characterized in that, The preset temperature monitoring points include pin monitoring points and / or preset test points; wherein, the pin monitoring points are set at the surface pins in the three-dimensional model of the printed circuit board, and the preset test points are set at a given test point position in the three-dimensional model of the device to be soldered.

6. The wave soldering temperature prediction method according to any one of claims 1 to 5, characterized in that, The process of constructing the thermal boundary conditions during the preheating stage includes: Establish the correspondence between the conveyor belt speed and the heating time in the preheating stage; The target ambient temperature is obtained, and a coupled model of hot air convection and infrared radiation is constructed; wherein the coupled model of hot air convection and infrared radiation includes hot air flow rate and target thermal radiation model.

7. The wave soldering temperature prediction method according to claim 6, characterized in that, The hot air flow rate is 2 L / s, and the target thermal radiation model is the S2S thermal radiation model.

8. The wave soldering temperature prediction method according to any one of claims 1 to 5, characterized in that, The process of constructing the thermal boundary conditions for the wave soldering stage includes: The temperature field after the preheating stage is completed is used as the initial condition for the wave soldering stage. Establish a correspondence between the heating time in the preheating stage and the solder spraying time in the wave soldering stage; wherein, the solder spraying time includes the first wave solder spraying time and the second wave solder spraying time, and the sum of the first wave solder spraying time and the second wave solder spraying time is less than 10 seconds; Establish the heat flux density equation at the solder-pin interface; wherein, the heat flux density equation is: ; Solder temperature For device temperature, For contact thermal resistance, For pin thermal resistance, The convective heat transfer coefficient is... For surface emissivity, It is the Stefan-Boltzmann constant; Heat flux density; A contact thermal resistance correction factor is established to adjust the contact thermal resistance; wherein, the contact thermal resistance correction factor is... , , and All are preset fitting coefficients. For conveyor belt speed, For welding time; Establish the correspondence between the conveyor belt speed and the solder temperature.

9. A temperature prediction device for wave soldering, characterized in that, include: The first acquisition module is used to acquire the thermal simulation model of the part to be processed; wherein, the thermal simulation model includes a three-dimensional model of the printed circuit board, the fixture and the device to be soldered, as well as the material thermal property parameters; The second acquisition module is used to acquire a digital twin model of the wave soldering process; wherein, the digital twin model includes the preheating stage and the thermal boundary conditions of the wave soldering stage in the wave soldering process; The simulation prediction module is used to simulate the transient temperature field of wave soldering on the thermal simulation model using the digital twin model, and to calculate the temperature data of the preset temperature monitoring points during the simulation process using a solver; wherein, the preset temperature monitoring points include temperature monitoring points in the three-dimensional model of the printed circuit board and / or the device to be soldered.

10. A temperature prediction device for wave soldering, characterized in that, include: Memory, used to store computer programs; A processor for executing the computer program to implement the steps of the wave soldering temperature prediction method as described in any one of claims 1 to 8.

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