Crest height correction method for wave soldering

Abstract

The invention relates to the technical field of wave soldering, and discloses a wave soldering wave crest height correction method which comprises the following steps: S1, simulation model establishment: determining preset welding process parameters; s2, preparation before correction is conducted, wherein fault-free operation and normal wave-soldering operation of welding equipment are guaranteed; s3, wave soldering debugging: determining the depth of the PCB simulation board immersed in the soldering flux wave crest; s4, wave-soldering test welding: correcting the height of the wave crest of the welding flux; s5, formal wave-soldering: correcting the wave crest of the soldering flux; and S6, welding quality monitoring and evaluation. The method comprises the following steps: determining preset welding process parameters; determining the depth of the soldering flux wave crest immersed in the PCB analog board; the preheating temperature is continuously adjusted for adjustment, so that the height of the wave crest of the correction solder is corrected; the height, the width and the outline shape of the soldering flux wave crest are monitored in real time, and the soldering flux wave crest is corrected in real time; the wave-soldering quality can be greatly improved, and the reliable and stable soldering quality is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of wave soldering, in particular to a wave soldering crest height correction method. Background Art

[0002] Wave soldering refers to the process of jetting molten soft solder into a solder wave peak as required by the design through an electric pump or electromagnetic pump. It can also be formed by injecting nitrogen into the solder pool, so that a printed circuit board pre-installed with components passes through the solder wave peak, achieving soft soldering of the mechanical and electrical connections between the component terminals or pins and the printed circuit board pads. The adjustment of the wave peak height of wave soldering plays a vital role in the soldering process. The wave peak height directly affects the wetting effect of the solder and the quality of the solder joints. The appropriate wave peak height can ensure that the solder fully wets the metal surface, flows into the small holes, and forms a round and full solder joint. Therefore, the wave peak height needs to be calibrated.

[0003] A Chinese patent discloses a wave soldering device that can automatically adjust the jet height (authorization announcement number CN208528270U). The patented technology controller controls the speed of the variable frequency motor based on the tin level in the tin pot detected by the tin level detection sensor and the change value of the wave crest jet height collected by the collection sensor, thereby changing the jet height. Since the controller knows the tin level in the tin pot and the change value of the wave crest jet height in real time, it can adjust the speed of the motor in real time to ensure the real-time consistency of the jet height and ensure the continuous stability of the welding quality. However, the accuracy of its adjustment of the wave crest height is not high, and it cannot effectively guarantee the quality of wave soldering. Summary of the Invention

[0004] The object of the present invention is to provide a wave soldering crest height correction method to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A wave soldering crest height correction method comprises the following steps:

[0007] S1. Simulation model establishment: According to the welding materials and welding equipment, the corresponding welding process is selected and a three-dimensional finite element network model is established. The wave soldering is simulated using historical process parameters to determine the preset welding process parameters.

[0008] S2. Preparation before calibration: First, check the status of the welding equipment to ensure that it can operate without any faults; then, run the welding equipment idle and debug the process parameters of the welding equipment to ensure that the welding equipment can perform wave soldering operations normally;

[0009] S3. Wave soldering debugging: Insert the soldering simulation component into the PCB simulation board and use the soldering process parameters preset in step S1. Make the soldering ends between the PCB simulation board and the soldering simulation component pass through the solder wave crest to perform simulated soldering. Adjust the distance between the solder wave crest and the PCB simulation board according to the soldering area of ​​the soldering ends, and determine the depth of the PCB simulation board immersed in the solder wave crest.

[0010] S4, wave soldering test: insert the soldering component to be soldered into the PCB board, and solder the soldering component to the PCB board according to the depth of the solder wave crest determined in step S3 and the soldering process parameters preset in step S1. During the soldering process, adjust the preheating temperature and correct the solder wave crest height;

[0011] S5, wave soldering formal welding: According to the depth of the solder wave crest determined in step S3, the soldering process parameters preset in step S1 and the solder wave crest height corrected in step S4, wave soldering production is formally carried out, and the solder wave crest height, width and contour shape are monitored in real time and compared with the parameter values ​​preset in step S1; the solder wave crest is corrected in real time;

[0012] S6. Welding quality monitoring and evaluation: Real-time recording, storage, and analysis of welding record data, evaluation of welding quality, and early warning in the event of abnormal conditions.

[0013] As a further solution of the present invention: in the step S1, the welding raw materials include tin solder, flux, welding components and PCB boards; the welding equipment includes a transportation system, a flux system, a preheating system, a welding system and a cooling system.

[0014] As a further solution of the present invention: in the step S1, the welding process parameters include conveying speed and tilt angle, flux amount, preheating temperature, soldering furnace temperature, tinning temperature, peak height, peak width, peak profile shape and cooling rate.

[0015] As a further solution of the present invention: in the step S3, the specific method of wave soldering debugging is as follows:

[0016] S31, installing a PCB simulation board with scale lines on a transport system in the welding equipment, and inserting a welding simulation component into the PCB simulation board;

[0017] S32, delivering the PCB simulation board and the welding simulation component to the top of the solder wave crest of the welding system through the transportation system, and using the welding process parameters preset in step S1, so that the welding ends of the PCB simulation board and the welding simulation component pass through the solder wave crest at the preset conveying speed and inclination angle, thereby achieving soft soldering of the PCB simulation board and the welding component;

[0018] S33. Observe the soldering area of ​​the soldering end, and then adjust the distance between the solder wave crest and the PCB simulation board until the depth of the PCB simulation board immersed in the solder wave crest is determined.

[0019] As a further solution of the present invention: in the step S4, the specific method of wave soldering trial soldering is as follows:

[0020] S41, inserting the soldering components to be soldered onto the PCB, and then mounting the PCB on the transport system at the tilt angle preset in step S1; and sending the PCB to the flux system to evenly spray a preset amount of flux;

[0021] S42, after being sent to the preheating system for preheating according to the preset preheating temperature, the PCB board is sent to the soldering system for trial soldering according to the soldering furnace temperature, tinning temperature, and wave height, width, and profile preset in step S1, based on the depth of the immersion solder wave determined in step S2;

[0022] S43, then send it to the cooling system for cooling according to the cooling speed preset in step S1;

[0023] S44, repeating steps S41 to S43, and continuously adjusting the preheating temperature in step S42, checking the quality of the solder joints, and determining the optimal preheating temperature;

[0024] S45. Repeat steps S41 to S43 again according to the optimal preheating temperature, and continuously adjust the wave crest height in step S42 to check the quality of the solder joints, thereby determining the optimal solder wave crest height and achieving solder wave crest height correction.

[0025] As a further solution of the present invention: the method for optimal preheating temperature control is as follows:

[0026] S441, collecting the temperature in the welding furnace of the welding system at time N and storing it in the sampling value module;

[0027] S442, using an external device to input a temperature setting value at time N, i.e., a preset preheating temperature, and storing it in a setting value unit;

[0028] S443, inputting the given temperature value and the sampled temperature value at time N into the single chip microcomputer, calculating the deviation value at time N and the deviation value increment compared to time (N-1);

[0029] S444. An incremental PID control algorithm is used to calculate the control value increment at time N, thereby achieving precise control of the temperature in the welding furnace of the welding system.

[0030] As a further solution of the present invention: welding quality monitoring and evaluation includes a data recording unit, a data analysis unit, a welding quality evaluation unit and an abnormality alarm unit, wherein:

[0031] The data recording unit is used to automatically record and store the operating data of the welding equipment and perform visual processing to facilitate subsequent analysis and tracing;

[0032] The data analysis unit is used to analyze the stored welding data, discover the operating rules and potential problems of the welding equipment, and optimize the welding production process;

[0033] The welding quality assessment unit is used to assess the quality of welding and set the lower limit of the quality level to ensure the welding quality.

[0034] The abnormal alarm unit is used to issue an alarm via WeChat, SMS, or email when the operating parameters of the welding equipment exceed the set range or the welding quality is lower than the lower limit of the quality grade.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The present invention first determines preset welding process parameters by establishing a three-dimensional finite element network model; then simulates welding according to the preset welding process parameters to determine the depth of a PCB simulation board immersed in a solder wave crest; then conducts trial welding according to the depth of the immersion in the solder wave crest and the preset welding process parameters, and continuously adjusts the preheating temperature to achieve correction of the solder wave crest height; then, according to the depth of the immersion in the solder wave crest, the preset welding process parameters and the corrected solder wave crest height, formally carries out wave soldering production, and through real-time monitoring of the solder wave crest height, width and contour shape, corrects the solder wave crest in real time to ensure that the crest height remains stable; thus, the wave soldering quality can be greatly improved, and reliable and stable welding quality can be guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The schematic diagram of the structure of a wave soldering crest height correction method is shown in FIG. DETAILED DESCRIPTION

[0038] See also Figure 1 In an embodiment of the present invention, a wave soldering crest height correction method includes the following steps:

[0039] S1. Simulation model establishment: According to the welding materials and welding equipment, the corresponding welding process is selected and a three-dimensional finite element network model is established. The wave soldering is simulated using historical process parameters to determine the preset welding process parameters.

[0040] S2. Preparation before calibration: First, check the status of the soldering equipment, such as whether each soldering equipment can be started normally, and whether the nozzle, tin pump, and tin bath in the soldering system are blocked or oxidized to ensure that the soldering equipment can operate without any problems. Then, run the soldering equipment idle and debug the process parameters of the soldering equipment, such as whether the transportation system can operate at the set speed and inclination; whether the flux system can spray the flux accurately and evenly; whether the preheating system can quickly and accurately heat the soldering material to the set temperature; whether the solder wave sprayed by the tin pump in the soldering system is stable and without turbulence; and whether the cooling system can dissipate the heat on the soldering material within the specified time to ensure that the soldering equipment can perform wave soldering operations normally.

[0041] S3. Wave soldering debugging: Insert the soldering simulation component into the PCB simulation board and use the soldering process parameters preset in step S1. Make the soldering ends between the PCB simulation board and the soldering simulation component pass through the solder wave crest to perform simulated soldering. Adjust the distance between the solder wave crest and the PCB simulation board according to the soldering area of ​​the soldering ends, and determine the depth of the PCB simulation board immersed in the solder wave crest.

[0042] S4, wave soldering test: Insert the soldering component to be soldered into the PCB board, and solder the soldering component to the PCB board according to the depth of the solder wave crest determined in step S3 and the soldering process parameters preset in step S1. During the soldering process, adjust the preheating temperature and calibrate the solder wave crest height. For example, the crest height should be 1 / 2 to 2 / 3 of the PCB board thickness. If the crest is too high, the molten solder will flow to the surface of the PCB board, forming bridge information. If the crest is too low, it is easy to cause solder leaks and cold solder joints.

[0043] S5. Wave soldering: According to the depth of the solder wave crest determined in step S3, the soldering process parameters preset in step S1, and the solder wave crest height corrected in step S4, wave soldering production is officially carried out. The height, width, and contour of the solder wave crest are monitored in real time. The sensor can use a laser displacement sensor, infrared thermal imager, and high-speed industrial camera, and then compared with the parameter values ​​preset in step S1. The solder wave crest is corrected in real time to ensure that the crest height remains stable.

[0044] S6. Welding quality monitoring and evaluation: Real-time recording, storage, and analysis of welding record data, evaluation of welding quality, and early warning in the event of abnormal conditions.

[0045] Preferably, in step S1, the welding raw materials include tin solder, flux, welding components and PCB boards; the welding equipment includes a transportation system, a flux system, a preheating system, a welding system and a cooling system; wherein the transportation system is used to realize the loading and transportation of the PCB boards in the welding furnace;

[0046] The flux system is used to remove the oxide layer of PCB boards and soldered components, keep the soldering surface clean, affect the balance of surface tension, reduce the contact angle and promote solder flow. By applying flux, heat can be effectively transferred to the soldering area.

[0047] The preheating system is used to preheat the PCB board and soldering components, such as preheating to 130-150°C for 1-3 minutes;

[0048] The soldering system uses dual-wave soldering. The first wave is a turbulent wave, ejected from a narrow nozzle with a fast flow rate, allowing the solder to penetrate the solder ends of small, high-density components well. The second wave is a smooth wave, which is used to solve the problems of solder short circuits and insufficient interface strength after tinning during the turbulent wave stage.

[0049] The cooling system is used to cool the temperature of the PCB board after it passes through the welding mechanism, which helps to enhance the bonding strength of the solder joints and facilitates subsequent processing on the production line.

[0050] Preferably, in step S1, the soldering process parameters include conveying speed and tilt angle, flux amount, preheating temperature, soldering furnace temperature, tinning temperature, wave peak height, wave peak width, wave peak profile shape and cooling rate; the tilted conveying angle can control the contact time between the PCB board and the solder wave peak surface, such as setting it to 4°~12°.

[0051] Preferably, in step S3, the specific method of wave soldering debugging is as follows:

[0052] S31, installing a PCB simulation board with scale lines on a transport system in the welding equipment, and inserting a welding simulation component into the PCB simulation board;

[0053] S32, delivering the PCB simulation board and the welding simulation component to the top of the solder wave crest of the welding system through the transportation system, and using the welding process parameters preset in step S1, so that the welding ends of the PCB simulation board and the welding simulation component pass through the solder wave crest at the preset conveying speed and inclination angle, thereby achieving soft soldering of the PCB simulation board and the welding component;

[0054] S33. Observe the soldering area of ​​the soldering end, and then adjust the distance between the solder wave crest and the PCB simulation board until the depth of the PCB simulation board immersed in the solder wave crest is determined.

[0055] Preferably, in step S4, the specific method of wave soldering trial soldering is as follows:

[0056] S41, inserting the soldering components to be soldered onto the PCB, and then mounting the PCB on the transport system at the tilt angle preset in step S1; and sending the PCB to the flux system to evenly spray a preset amount of flux;

[0057] S42, after being sent to the preheating system for preheating according to the preset preheating temperature, the PCB board is sent to the soldering system for trial soldering according to the soldering furnace temperature, tinning temperature, and wave height, width, and profile preset in step S1, based on the depth of the immersion solder wave determined in step S2;

[0058] S43, then send it to the cooling system for cooling according to the cooling speed preset in step S1;

[0059] S44, repeating steps S41 to S43, and continuously adjusting the preheating temperature in step S42, checking the quality of the solder joints, and determining the optimal preheating temperature;

[0060] S45. Repeat steps S41 to S43 according to the optimal preheating temperature, and continuously adjust the wave crest height in step S42, check the quality of the solder joints, and thus determine the optimal soldering wave crest height to achieve soldering wave crest height correction; if the solder joints are pointed or the number of solder bridges increases, it is necessary to lower the wave crest height by 0.12 to 0.2 mm each time to reduce the solder flow; if there are cold solder joints or incomplete solder joints, it is necessary to increase the wave crest height by 0.2 to 0.3 mm each time to increase the solder pressure; if adjustment is required, the solder wave crest height can be adjusted by adjusting the tin pump speed or the opening degree of the wave crest height regulating valve.

[0061] Preferably, in step S44, the method for optimal preheating temperature control is as follows:

[0062] S441, collecting the temperature in the welding furnace of the welding system at time N and storing it in the sampling value module;

[0063] S442, using an external device to input a temperature setting value at time N, i.e., a preset preheating temperature, and storing it in a setting value unit;

[0064] S443, inputting the given temperature value and the sampled temperature value at time N into the single chip microcomputer, calculating the deviation value at time N and the deviation value increment compared to time (N-1);

[0065] S444. An incremental PID control algorithm is used to calculate the control value increment at time N, thereby achieving precise control of the temperature in the welding furnace of the welding system.

[0066] Preferably, in step S6, the welding quality monitoring and evaluation includes a data recording unit, a data analysis unit, a welding quality evaluation unit and an abnormality alarm unit, wherein:

[0067] The data recording unit is used to automatically record and store the operating data of the welding equipment and perform visual processing to facilitate subsequent analysis and tracing;

[0068] The data analysis unit is used to analyze the stored welding data, discover the operating rules and potential problems of the welding equipment, and optimize the welding production process;

[0069] The welding quality assessment unit is used to assess the quality of welding and set the lower limit of the quality level to ensure the welding quality.

[0070] The abnormal alarm unit is used to issue an alarm via WeChat, SMS, or email when the operating parameters of the welding equipment exceed the set range or the welding quality is lower than the lower limit of the quality grade.

[0071] The above is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A wave soldering crest height correction method, characterized in that: The following steps are involved: S1. Simulation model establishment: According to the welding materials and welding equipment, the corresponding welding process is selected and a three-dimensional finite element network model is established. The wave soldering is simulated using historical process parameters to determine the preset welding process parameters. S2. Preparation before calibration: First, check the status of the welding equipment to ensure that it can operate without any faults; then, run the welding equipment idle and debug the process parameters of the welding equipment to ensure that the welding equipment can perform wave soldering operations normally; S3, wave soldering debugging: insert the welding simulation components into the PCB simulation board and use the welding process parameters preset in step S1; The soldering ends between the PCB simulation board and the welding simulation components are passed through the solder wave crest to perform simulated welding. The distance between the solder wave crest and the PCB simulation board is adjusted according to the welding area of ​​the soldering ends, and the depth of the PCB simulation board immersed in the solder wave crest is determined; S4, wave soldering test: insert the soldering component to be soldered into the PCB board, and solder the soldering component to the PCB board according to the depth of the solder wave crest determined in step S3 and the soldering process parameters preset in step S1. During the soldering process, adjust the preheating temperature and correct the solder wave crest height; S5. Wave soldering: According to the depth of the solder wave crest determined in step S3, the soldering process parameters preset in step S1, and the solder wave crest height corrected in step S4, wave soldering production is officially carried out. The height, width, and contour of the solder wave crest are monitored in real time and compared with the parameter values ​​preset in step S1. Correct solder wave peaks in real time; S6. Welding quality monitoring and evaluation: Real-time recording, storage, and analysis of welding record data, evaluation of welding quality, and early warning in the event of abnormal conditions.

2. A wave soldering crest height correction method according to claim 1, characterized in that: In the step S1, the welding raw materials include tin solder, flux, welding components and PCB boards; the welding equipment includes a transportation system, a flux system, a preheating system, a welding system and a cooling system.

3. A wave soldering crest height correction method according to claim 1, characterized in that: In the step S1, the soldering process parameters include conveying speed and tilt angle, flux amount, preheating temperature, soldering furnace temperature, tinning temperature, wave peak height, wave peak width, wave peak profile shape and cooling speed.

4. A wave soldering crest height correction method according to claim 1, characterized in that: In the step S3, the specific method of wave soldering debugging is as follows: S31, installing a PCB simulation board with scale lines on a transport system in the welding equipment, and inserting a welding simulation component into the PCB simulation board; S32, delivering the PCB simulation board and the welding simulation component to the top of the solder wave crest of the welding system through the transportation system, and using the welding process parameters preset in step S1, so that the welding ends of the PCB simulation board and the welding simulation component pass through the solder wave crest at the preset conveying speed and inclination angle, thereby achieving soft soldering of the PCB simulation board and the welding component; S33. Observe the soldering area of ​​the soldering end, and then adjust the distance between the solder wave crest and the PCB simulation board until the depth of the PCB simulation board immersed in the solder wave crest is determined.

5. A wave soldering crest height correction method according to claim 1, characterized in that: In the step S4, the specific method of wave soldering trial soldering is as follows: S41, inserting the soldering components to be soldered onto the PCB, and then mounting the PCB on the transport system at the tilt angle preset in step S1; and sending the PCB to the flux system to evenly spray a preset amount of flux; S42, after being sent to the preheating system for preheating according to the preset preheating temperature, the PCB board is sent to the soldering system for trial soldering according to the soldering furnace temperature, tinning temperature, and wave height, width, and profile preset in step S1, based on the depth of the immersion solder wave determined in step S2; S43, then send it to the cooling system for cooling according to the cooling speed preset in step S1; S44, repeating steps S41 to S43, and continuously adjusting the preheating temperature in step S42, checking the quality of the solder joints, and determining the optimal preheating temperature; S45. Repeat steps S41 to S43 again according to the optimal preheating temperature, and continuously adjust the wave crest height in step S42 to check the quality of the solder joints, thereby determining the optimal solder wave crest height and achieving solder wave crest height correction.

6. A wave soldering crest height correction method according to claim 5, characterized in that: In the step S44, the method for controlling the optimal preheating temperature is as follows: S441, collecting the temperature in the welding furnace of the welding system at time N and storing it in the sampling value module; S442, using an external device to input a temperature setting value at time N, i.e., a preset preheating temperature, and storing it in a setting value unit; S443, inputting the given temperature value and the sampled temperature value at time N into the single chip microcomputer, calculating the deviation value at time N and the deviation value increment compared to time (N-1); S444. An incremental PID control algorithm is used to calculate the control value increment at time N, thereby achieving precise control of the temperature in the welding furnace of the welding system.

7. A wave soldering crest height correction method according to claim 1, characterized in that: In the step S6, the welding quality monitoring and evaluation includes a data recording unit, a data analysis unit, a welding quality evaluation unit and an abnormality alarm unit, wherein: The data recording unit is used to automatically record and store the operating data of the welding equipment and perform visual processing to facilitate subsequent analysis and tracing; The data analysis unit is used to analyze the stored welding data, discover the operating rules and potential problems of the welding equipment, and optimize the welding production process; The welding quality assessment unit is used to assess the quality of welding and set the lower limit of the quality level to ensure the welding quality. The abnormal alarm unit is used to issue an alarm via WeChat, SMS, or email when the operating parameters of the welding equipment exceed the set range or the welding quality is lower than the lower limit of the quality grade.

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