A variable polarity seam welding power source for device packaging and a welding quality monitoring method

Abstract

The application discloses a variable polarity seam welding power supply for device packaging and a welding quality monitoring method. The variable polarity seam welding power supply comprises a power main circuit module and a control system module. The power main circuit module comprises a power input module, a power conversion module, an energy storage capacitor group module, an H-bridge chopper module and an output module. The method comprises the following steps: turning on the variable polarity seam welding power supply to weld a device packaging workpiece, obtaining an average dynamic resistance sequence of the device packaging workpiece after welding, determining a Spearman correlation coefficient of the device packaging workpiece after welding based on the average dynamic resistance sequence of the device packaging workpiece after welding, and setting a threshold value of the Spearman correlation coefficient to determine the quality of the device packaging workpiece after welding. The application can improve the welding quality of the device packaging workpiece by precisely controlling the welding quality monitoring method software. The application can be widely applied to the technical field of device packaging welding.

Description

Technical Field

[0001] This application relates to the field of device packaging and welding technology, and in particular to a variable polarity seam welding power supply and welding quality monitoring method for device packaging. Background Technology

[0002] Packaging is the process of assembling integrated circuits into a final product. The packaging process requires a reliable connection between the outer casing and cover plate of the package to protect the internal integrated circuit and achieve a hermetic seal. Resistance seam welding, a type of resistance welding, is one of the mainstream processes for device packaging connections. It typically involves continuous operation with multiple overlapping weld points, one pulse of current corresponding to one solder joint, forming a weld seam. Device packaging involves the simultaneous formation of two weld seams. The welding current flows through multiple interfaces—electrode-molten zone-cover plate-molten zone-electrode—leading to uneven heat distribution between the two molten zones due to polarity effects.

[0003] Currently, the power supplies used in resistance seam welding for device packaging are typically inverter-type power supplies, i.e., inverter seam welding power supplies, which complete power conversion through an inverter-centric topology. Regarding quality monitoring, the current resistance spot welding field mostly employs offline quality monitoring methods such as statistical analysis or machine learning. The shortcomings of existing inverter seam welding power supplies are twofold: firstly, DC inverters often use 4kHz PWM control, and the low control frequency is not conducive to precise heat control; unidirectional current output cannot solve the problem of uneven heat distribution. Secondly, AC inverters use PFM control, which has low efficiency under heavy loads, and to prevent transformer magnetic saturation, strict requirements are placed on the positive and negative symmetry of the output waveform, making waveform control inflexible. The shortcomings of existing quality monitoring methods are twofold: firstly, existing statistical analysis methods have not been integrated with the characteristics of the seam welding process, resulting in unreliable accuracy; secondly, offline quality monitoring methods require a large amount of data to accurately match features and cannot identify welding process anomalies in real time.

[0004] In summary, the technical problems existing in the relevant technologies need to be improved. Summary of the Invention

[0005] The main objective of this application is to propose a variable polarity seam welding power supply and a welding quality monitoring method for device packaging, which can improve the welding quality of device packaged workpieces through precise control and the built-in welding quality monitoring software.

[0006] To achieve the above objectives, one aspect of this application proposes a variable polarity seam bonding power supply for device packaging. The variable polarity seam bonding power supply includes a power main circuit module and a control system module. The power main circuit module includes a power input module, a power conversion module, an energy storage capacitor bank module, an H-bridge chopper module, and an output module. The output terminal of the control system module is connected to the H-bridge chopper module of the power main circuit module, and the output module of the power main circuit module is connected to the input terminal of the control system module. Wherein:

[0007] The power main circuit module is used to provide welding current to the output module;

[0008] The control system module is used to control the operation of the variable polarity seam welding power supply.

[0009] In some embodiments, the power main circuit module includes a power input module, a power conversion module, an energy storage capacitor bank module, an H-bridge chopper module, and an output module. The output terminal of the power input module is connected to the input terminal of the power conversion module, the output terminal of the power conversion module is connected to the input terminal of the energy storage capacitor bank module, the output terminal of the energy storage capacitor bank module is connected to the input terminal of the H-bridge chopper module, and the output terminal of the H-bridge chopper module is connected to the input terminal of the output module.

[0010] The power input module is used to obtain power input from the power grid;

[0011] The power conversion module is used to convert the power input to AC or DC.

[0012] The energy storage capacitor bank module is used to receive the DC power input and store it in the form of electrical energy.

[0013] The H-bridge chopper module is used to control the output of the electrical energy to generate welding current;

[0014] The output module is used to output the welding current to the device packaging workpiece.

[0015] In some embodiments, the H-bridge chopper module includes a first MOSFET, a second MOSFET, a third MOSFET, a fourth MOSFET, a first welding cable inductor, and a second welding cable inductor, wherein the first MOSFET includes a first parasitic diode, the second MOSFET includes a second parasitic diode, the third MOSFET includes a third parasitic diode, and the fourth MOSFET includes a fourth parasitic diode.

[0016] In some embodiments, the control system module includes a main control chip module, a drive circuit module, a sampling module, a human-machine interaction module, a digital quantity module, a data storage module, and a data communication module. The first output terminal of the main control chip module is connected to the input terminal of the drive circuit module; the second output terminal of the main control chip module is connected to the input terminal of the human-machine interaction module; the third output terminal of the main control chip module is connected to the input terminal of the digital quantity module; the fourth output terminal of the main control chip module is connected to the input terminal of the data storage module; the fifth output terminal of the main control chip module is connected to the input terminal of the data communication module; the output terminal of the sampling module is connected to the first input terminal of the main control chip module; the output terminal of the human-machine interaction module is connected to the second input terminal of the main control chip module; the output terminal of the digital quantity module is connected to the third input terminal of the main control chip module; the output terminal of the data storage module is connected to the fourth input terminal of the main control chip module; and the output terminal of the data communication module is connected to the fifth input terminal of the main control chip module. Wherein:

[0017] The main control chip module is used to control the operation of the variable polarity seam welding power supply;

[0018] The drive circuit module is used to amplify the power of the PWM signal emitted by the main control chip module.

[0019] The sampling module is used to perform signal conditioning processing on the output current and output voltage of the main control chip module and convert them into digital quantities.

[0020] The human-computer interaction module is used to acquire welding parameters and display the current welding status;

[0021] The digital input module is used to read the start signal;

[0022] The data storage module is used to store welding data;

[0023] The data communication module is used to exchange information with external devices.

[0024] To achieve the above objectives, another aspect of this application proposes a method for monitoring soldering quality in device packaging, the method comprising:

[0025] The variable polarity seam welding power supply is turned on to perform welding on the workpiece to be packaged, and the average dynamic resistance sequence of the workpiece after welding is obtained.

[0026] Based on the average dynamic resistance sequence of the device packaged workpiece after welding, the Spearman correlation coefficient of the device packaged workpiece after welding is determined.

[0027] Set a threshold for the Spearman correlation coefficient to determine the quality of the device packaged components after soldering;

[0028] If the Spearman correlation coefficient is less than the Spearman correlation coefficient threshold, then the quality of the device packaged workpiece after welding is unqualified.

[0029] If the Spearman correlation coefficient is greater than the Spearman correlation coefficient threshold, then the quality of the device packaged workpiece after welding is qualified.

[0030] In some embodiments, the step of activating the variable polarity seam welding power supply to perform welding on the device package workpiece and obtaining the average dynamic resistance sequence of the device package workpiece after welding includes:

[0031] The electrode lifespan of the variable polarity seam welding process for device packaging is specified according to actual requirements.

[0032] During the electrode lifecycle of the aforementioned variable polarity seam welding process for device packaging, the device packaging workpiece is welded.

[0033] The data storage module of the variable polarity seam welding power supply reads the pulse current data and pulse voltage data of the device packaged workpiece after welding.

[0034] The pulse current data and the pulse voltage data of a preset proportion are selected and their arithmetic average is calculated to obtain the average dynamic resistance sequence of the device packaged workpiece after welding.

[0035] In some embodiments, the expression for calculating the arithmetic mean is specifically as follows:

[0036]

[0037] In the above formula, m represents the solder joint number of a certain device package workpiece, n represents the number of pulse current or voltage data points corresponding to solder joint number m, k represents the sequence number of the pulse current or voltage data point corresponding to the solder joint, and AVG represents calculating the average value. This refers to the solder joint with serial number m on a component package for a certain device, where n values ​​are obtained using pulse current or voltage data. Calculate the average value.

[0038] In some embodiments, determining the Spearman correlation coefficient of the device package workpiece after welding based on the average dynamic resistance sequence of the device package workpiece includes:

[0039] The average dynamic resistance sequence of the device packaged workpiece after welding is converted to obtain a two-dimensional average dynamic resistance sequence.

[0040] The two-dimensional average dynamic resistance sequence is selected and sorted according to the first value of each element to construct a first index number;

[0041] The second value of each element after sorting the two-dimensional average dynamic resistance sequence is selected to construct the second index number;

[0042] Extract all the second index numbers to obtain an index array;

[0043] The Spearman correlation coefficient is calculated on the index array to determine the Spearman correlation coefficient of the device packaged workpiece after welding.

[0044] In some embodiments, the expression for calculating the Spearman correlation coefficient is as follows:

[0045]

[0046] In the above formula, p i This represents the Spearman correlation coefficient, where j represents the j-th value in each element, and i represents the i-th device package component. This represents the square of the difference between the indices of the j-th value in the dynamic resistance sequence of workpiece i and workpiece i-1 in their respective sequences.

[0047] In some embodiments, the method further includes a correction process for the Spearman correlation coefficient threshold, specifically including:

[0048] Based on the aforementioned uncorrected Spearman correlation coefficient threshold, the device package workpieces are classified as qualified and unqualified.

[0049] The average value and standard deviation of the Spearman correlation coefficients for the qualified device packaging workpieces and the average value and standard deviation of the Spearman correlation coefficients for the unqualified device packaging workpieces are obtained respectively.

[0050] Weighting coefficients are set based on the tolerance levels in actual production for two scenarios: a workpiece with abnormal quality is judged as normal and a workpiece with normal quality is judged as abnormal.

[0051] The Spearman correlation coefficient threshold is corrected based on the mean and standard deviation and the weighting coefficient.

[0052] The embodiments of this application include at least the following beneficial effects: This application provides a variable polarity seam welding power supply and a welding quality monitoring method for device packaging. This scheme integrates an energy storage capacitor bank module and an H-bridge chopper module into a power main circuit module, making full use of the voltage regulation characteristics of the energy storage capacitor and the high-frequency switching characteristics of the MOSFET, ensuring excellent output current rise speed and low output ripple. The H-bridge chopper module ensures a complete low-impedance current path in all four modes and improves the welding quality of the device package workpiece through precise control. Further welding quality detection is performed on the device package workpiece to obtain the average dynamic resistance sequence after welding. The main factors related to seam welding quality are attributed to the dynamic resistance of the seam welding process. The original data is extracted by calculating the average value. Based on the average dynamic resistance sequence after welding, the Spearman correlation coefficient of the device package workpiece is determined. The Spearman correlation coefficient is used to measure the similarity of the average dynamic resistance sequences of adjacent workpieces in time as a feature for anomaly detection. The welding quality of the device package workpiece is improved by incorporating quality monitoring software into the power supply. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of a variable polarity seam welding power supply for device packaging provided in an embodiment of this application;

[0054] Figure 2 This is a schematic diagram of the power main circuit module provided in an embodiment of this application;

[0055] Figure 3 This is a schematic diagram of the waveform control output of the power main circuit module provided in the embodiment of this application;

[0056] Figure 4 This is a schematic diagram illustrating the steps of a welding quality monitoring method for device packaging provided in an embodiment of this application;

[0057] Figure 5 This is a schematic diagram illustrating the specific implementation process of the welding quality monitoring method provided in the embodiments of this application.

[0058] Figure descriptions: ① AC pulse mode; ② Positive pulse mode; ③ Variable polarity mode. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit it. In the following description, when referring to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with those of this application; they are merely examples of power supplies and methods consistent with some aspects of the embodiments of this application as detailed in the appended claims.

[0060] It is understood that the terms “first,” “second,” etc., used in this application may be used herein to describe various concepts, but unless otherwise stated, these concepts are not limited by these terms. These terms are only used to distinguish one concept from another. For example, without departing from the scope of the embodiments of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the words “if,” “when,” or “in response to a determination” as used herein may be interpreted as “when…” or “when…” or “in response to a determination.”

[0061] As used in this application, the terms "at least one", "multiple", "each", "any", etc., "at least one" includes one, two or more, "multiple" includes two or more, "each" refers to each of the corresponding multiples, and "any" refers to any one of the multiples.

[0062] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.

[0063] Reference Figure 1 , Figure 1 This is a schematic diagram of a variable polarity seam bonding power supply for device packaging provided in an embodiment of the present invention, with reference to... Figure 1 The power supply includes a main power circuit module and a control system module. The main power circuit module includes a power input module, a power conversion module, an energy storage capacitor bank module, an H-bridge chopper module, and an output module. The output terminal of the control system module is connected to the H-bridge chopper module of the main power circuit module, and the output module of the main power circuit module is connected to the input terminal of the control system module.

[0064] The main power circuit module is used to provide welding current to the output module;

[0065] Specifically, the power main circuit module includes a power input module, a power conversion module, an energy storage capacitor bank module, an H-bridge chopper module, and an output module. The output terminal of the power input module is connected to the input terminal of the power conversion module, the output terminal of the power conversion module is connected to the input terminal of the energy storage capacitor bank module, the output terminal of the energy storage capacitor bank module is connected to the input terminal of the H-bridge chopper module, and the output terminal of the H-bridge chopper module is connected to the input terminal of the output module.

[0066] The H-bridge chopper module includes a first MOSFET, a second MOSFET, a third MOSFET, a fourth MOSFET, a first welding cable inductor, and a second welding cable inductor. The first MOSFET includes a first parasitic diode, the second MOSFET includes a second parasitic diode, the third MOSFET includes a third parasitic diode, and the fourth MOSFET includes a fourth parasitic diode.

[0067] More specifically, such as Figure 2 As shown, the 220V AC power input from the power input module is converted into stable DC power by the AC-DC conversion module (i.e., the power conversion module) to charge the energy storage capacitor group C. The H-bridge chopper module consists of two pairs of MOSFETs: the first MOSFET Q1 and the fourth MOSFET Q4, and the second MOSFET Q2 and the third MOSFET Q3. The first MOSFET Q1 and the second MOSFET Q2 are high-frequency switching transistors, and the output is controlled by chopping in PWM mode with a working frequency of 100kHz. The third MOSFET Q3 and the fourth MOSFET Q4 are current direction control transistors; the MOSFET pair is only in working state when the transistor is turned on. The parasitic diodes of the first MOSFET Q1, the second MOSFET Q2, the third MOSFET Q3, and the fourth MOSFET Q4 are denoted as the first parasitic diode D1, the second parasitic diode D2, the third parasitic diode D3, and the fourth parasitic diode D4, respectively. La and Lb are the first welding cable inductance and the second welding cable inductance, respectively.

[0068] Furthermore, the working mode of the H-bridge chopper module in this application embodiment is described. When the third MOSFET Q3 is turned off and the fourth MOSFET Q4 is turned on, the first MOSFET Q1 and the fourth MOSFET Q4 are working, which can be divided into the following two states: When the fourth MOSFET Q4 and the first MOSFET Q1 are turned on, the current path flows sequentially through the energy storage capacitor group C, the first MOSFET Q1, the first welding cable inductor La, the device package workpiece, the second welding cable inductor Lb, the fourth MOSFET Q4, and the energy storage capacitor group C; if the fourth MOSFET Q4 is turned on and the first MOSFET Q1 is turned off, the current path is the first welding cable inductor La, the device package workpiece, the second welding cable inductor Lb, the fourth MOSFET Q4, the third parasitic diode D3, and the first welding cable inductor La. When the fourth MOSFET Q4 is off and the third MOSFET Q3 is on, the second MOSFET Q2 and the third MOSFET Q3 operate, which can be divided into the following two states: When the third MOSFET Q3 and the second MOSFET Q2 are on, the current path is: energy storage capacitor group C, second MOSFET Q2, second welding cable inductor Lb, device package workpiece-first welding cable inductor La, third MOSFET Q3, energy storage capacitor group C; if the third MOSFET Q3 is on and the second MOSFET Q2 is off, the current path is: second welding cable inductor Lb, device package workpiece, first welding cable inductor La, third MOSFET Q3, fourth parasitic diode D4, second welding cable inductor Lb.

[0069] Furthermore, such as Figure 3 As shown, the complete waveform in the figure corresponds to the formation of a complete weld seam on a single workpiece. Each pair of positive and negative pulses (configurable to three modes: ①, ②, and ③) corresponds to a weld point. The duration (i.e., heating time) is set with a minimum resolution of 10µs according to actual needs. During this period, the control system uses a PWM chopping control at a control frequency of 100kHz to maintain stable output and saves the sampled data to the SD data acquisition card at the same frequency. 1ms of welding time corresponds to 100 current and 100 voltage data points. The interval between pairs of positive and negative pulses is called the cooling time. During this period, the electrode rolls to the next weld point of the weld seam. Within the rectangular area including the shaded area, the pulse amplitude and the number of pulses can be adjusted arbitrarily. The positive and negative pulse pairs can be configured as positive pulses only or negative pulses only to meet diverse welding requirements.

[0070] In this embodiment, the power input module is used to obtain power input from the power grid; the power conversion module is used to convert the power input to AC or DC; the energy storage capacitor bank module is used to receive DC power input and store it in the form of electrical energy; the H-bridge chopper module is used to control the output of electrical energy and generate welding current; and the output module is used to output welding current to the device packaging workpiece.

[0071] The control system module is used to control the operation of the variable polarity seam welding power supply.

[0072] Specifically, the control system module includes a main control chip module, a drive circuit module, a sampling module, a human-machine interface module, a digital input / output module, a data storage module, and a data communication module. The first output terminal of the main control chip module is connected to the input terminal of the drive circuit module, the second output terminal of the main control chip module is connected to the input terminal of the human-machine interface module, the third output terminal of the main control chip module is connected to the input terminal of the digital input / output module, the fourth output terminal of the main control chip module is connected to the input terminal of the data storage module, the fifth output terminal of the main control chip module is connected to the input terminal of the data communication module, the output terminal of the sampling module is connected to the first input terminal of the main control chip module, the output terminal of the human-machine interface module is connected to the second input terminal of the main control chip module, the output terminal of the digital input / output module is connected to the third input terminal of the main control chip module, the output terminal of the data storage module is connected to the fourth input terminal of the main control chip module, and the output terminal of the data communication module is connected to the fifth input terminal of the main control chip module.

[0073] In this embodiment, the main control chip module is used to control the operation of the variable polarity seam welding power supply; the drive circuit module is used to amplify the PWM signal emitted by the main control chip module; the sampling module is used to perform signal conditioning processing on the output current and output voltage of the main control chip module and convert them into digital quantities; the human-machine interaction module is used to acquire welding parameters and display the current welding status; the switch module is used to read the start signal; the data storage module is used to store welding data; and the data communication module is used to exchange information with external devices.

[0074] It should be noted that the drive circuit module amplifies the PWM signal emitted by the chip to control the switching devices—transistors—in the main circuit; the sampling module is responsible for acquiring the output current of the power supply and the voltage signal between the two rollers, which are then converted into digital quantities by the chip's ADC after signal conditioning and scaling. The human-machine interaction module is responsible for reading welding parameters and displaying the current welding status; the switching module is responsible for interacting with external signals such as the start signal; the data storage module stores welding process information through an SD data acquisition card as a removable storage medium; and the data communication module interacts with other devices based on an RS485 unit using a predetermined communication protocol.

[0075] In summary, the main power circuit fully utilizes the voltage regulation characteristics of the energy storage capacitor and the high-frequency switching characteristics of the MOSFET to ensure excellent output current rise speed and low output ripple. The H-bridge high-frequency switching + current direction control drive method ensures a complete low-impedance current path in all four modes, simplifies commutation during mode switching, and makes it easy to control the polarity of the output current. The hardware and software are completely decoupled, providing a high degree of freedom in waveform control. Data is stored directly in the control system using an SD card, providing a high-sampling-rate data acquisition and storage method at minimal cost.

[0076] It should be noted that the existing online quality assessment of the welding process has the following problems: First, electrode wear occurs during the welding process, and in actual production, electrodes are often replaced periodically by counting the number of workpieces; second, the surface precision and quality of different workpieces vary; third, the overlap of weld points on a single workpiece varies at different locations in the weld, resulting in inconsistent welding current shunting; fourth, the workpiece accumulates heat during the continuous formation of the weld, eventually reaching a state where the heat generated by weld point formation and the overall continuous heat dissipation are balanced; and fifth, there are contact and welding pressure fluctuations during the relative movement of the roller and the workpiece.

[0077] Based on this, the changes can be attributed to the dynamic resistance of the welding area: electrode wear, pressure fluctuations, and differences in workpiece surface quality affect the contact between the electrode and the workpiece, thus leading to changes in contact resistance; welding current shunting can be considered as a reduction in the overall resistance of the area; material resistance is positively correlated with temperature, and heat accumulation will lead to an increase in area resistance. Therefore, the dynamic resistance of the welding process can serve as an information source for quality assessment. In actual production, it can be found that for a stable welding process, the characteristics of its dynamic resistance should not exhibit significant abrupt changes. Therefore, quality assessment is based on the following ideas: the phenomena described in points three and four of the existing online quality assessment of the welding process are attributed to inherent characteristics in the weld formation process, that is, under stable process conditions, the dynamic resistance characteristic curves of any two workpieces should be similar; the phenomena described in points one and two are characteristics that change over time, but under stable process conditions, i.e., without abnormal conditions such as spatter that significantly wear down the electrode, the electrode wear is considered to be gradual. At the same time, if there is no contamination on the workpiece surface, the differences in surface quality between different workpieces are considered to be within a controllable range, that is, the changes in the characteristics described in points one and two should all be within a controlled range. Fifthly, random factors are considered, but controllability is ensured by the rational design of the electrodes and their motion control mechanisms.

[0078] Please see Figure 4 and Figure 5 This application also provides a welding quality monitoring method for device packaging, which can realize the above-mentioned variable polarity seam welding power supply for device packaging. The method includes:

[0079] S100: Turn on the variable polarity seam welding power supply to perform welding on the device package workpiece and obtain the average dynamic resistance sequence of the device package workpiece after welding.

[0080] It should be noted that in some embodiments, step S100 may include: S110, specifying the electrode usage cycle of the variable polarity seam welding process for device packaging according to actual needs; S120, performing welding processing on the device packaging workpiece within the electrode usage cycle of the variable polarity seam welding process for device packaging; S130, reading the pulse current data and pulse voltage data of the device packaging workpiece after welding through the data storage module of the variable polarity seam welding power supply; S140, performing arithmetic mean calculation processing on the pulse current data and pulse voltage data with a preset amount ratio to obtain the average dynamic resistance sequence of the device packaging workpiece after welding.

[0081] In some specific embodiments, the electrodes are replaced every fixed number of welded workpieces in actual production. Therefore, data processing and subsequent quality assessment are based on the electrode's lifespan, hereinafter referred to as the electrode usage cycle. After each workpiece (weld) is welded within the electrode usage cycle, the MCU first reads the pulse current and voltage data corresponding to each weld point from the SD card and calculates the dynamic resistance. To prevent inconsistencies in current and voltage phases during output current rises and falls, which could lead to abnormal dynamic resistance calculations, only the middle 90% of the data is used for dynamic resistance calculation. Assume the dynamic resistance value corresponding to the m-th weld point of a certain workpiece is... Where n is the number of valid data points remaining after taking 90%, the expression for calculating their arithmetic mean is:

[0082]

[0083] In the above formula, m represents the solder joint number of a certain device package workpiece, n represents the number of pulse current (voltage) data points corresponding to solder joint number m, k represents the sequence number of the pulse current (voltage) data points corresponding to the solder joint, and AVG represents calculating the average value. This represents the solder joint with serial number m in the package of a certain device, for n solder joints obtained using pulse current (voltage) data. Calculate the average value.

[0084] All of the obtained from the packaged workpiece of a certain device Its average dynamic resistance sequence can be expressed as: Let it be denoted as x (i) =(y1,y2,…,y l In the formula, l represents the number of solder joints of the device package workpiece, and i is the serial number of the workpiece in the electrode usage cycle.

[0085] S200. Based on the average dynamic resistance sequence of the device package workpiece after welding, determine the Spearman correlation coefficient of the device package workpiece after welding.

[0086] It should be noted that in some embodiments, step S200 may include: S210, performing conversion processing on the average dynamic resistance sequence after welding of the device packaging workpiece to obtain a two-dimensional average dynamic resistance sequence; S220, selecting and sorting the two-dimensional average dynamic resistance sequence according to the first value of each element to construct a first index number; S230, selecting the second value of each element after sorting the two-dimensional average dynamic resistance sequence to construct a second index number; S240, extracting all the second index numbers to obtain an index array; S250, calculating the Spearman correlation coefficient for the index array to determine the Spearman correlation coefficient after welding of the device packaging workpiece.

[0087] In some specific embodiments, according to step S1, the average dynamic resistance sequences of all N workpieces within the current electrode usage cycle are obtained. Calculate the Spearman correlation coefficient for workpiece i (2 ≤ i ≤ N), that is, the correlation coefficient is:

[0088]

[0089] In the above formula, p i represents the Spearman correlation coefficient, j represents the j-th value in each element, i represents the i-th device packaging workpiece, represents the square of the difference in the indices of the j-th value in the dynamic resistance sequences of workpiece i and workpiece i - 1 in their respective sequences.

[0090] To quickly obtain the indices corresponding to each point in the dynamic resistance sequence of workpiece i, the following method is adopted: First, convert the dynamic resistance sequence x (i) =(y1, y2, …, y n ) into a two-dimensional x (i) =((y1, 1), (y2, 2), …, (y n , n)), then sort the two-dimensional data unit according to the first value of each element, and then sequentially read the second value of each element after sorting the two-dimensional data unit, and extract this value as a new array to become the index array According to this method, all N - 1 index difference arrays can be obtained.

[0091] Calculate N - 1 correlation coefficients according to the Spearman correlation coefficient calculation formula, and take p i as the quality evaluation feature of workpiece i. When p i is closer to 1, the correlation is stronger. At this time, it is considered that the process stability is good and no obvious quality abnormality has occurred. Under experimental conditions, the correlation coefficient threshold p0 of normal-quality workpieces is measured as the initial boundary for anomaly detection. When p i < p0, it is considered that workpiece i is unqualified. If workpiece i - 1 is unqualified, then take workpiece i - 2 for calculation, and so on.

[0092] S300: Set the Spearman correlation coefficient threshold to determine the quality of the device packaged workpiece after welding;

[0093] S400. If the Spearman correlation coefficient is less than the Spearman correlation coefficient threshold, the quality of the device packaged workpiece after welding is unqualified.

[0094] S500. If the Spearman correlation coefficient is greater than the Spearman correlation coefficient threshold, then the quality of the device packaged workpiece after welding is qualified.

[0095] It should also be noted that the embodiments of this application also include a correction process for the Spearman correlation coefficient threshold, specifically as follows:

[0096] Based on the uncorrected Spearman correlation coefficient threshold, device packaged parts are classified into qualified and unqualified. The mean and standard deviation of the Spearman correlation coefficient for qualified device packaged parts and the mean and standard deviation of the Spearman correlation coefficient for unqualified device packaged parts are obtained respectively. Based on the tolerance for two situations in actual production—a qualified part being judged as normal and a normal part being judged as abnormal—weighting coefficients are set. The Spearman correlation coefficient threshold is corrected based on the mean and standard deviation of the Spearman correlation coefficient and the weighting coefficients.

[0097] Specifically, after acquiring a certain amount of data, the correlation coefficient threshold will be automatically adjusted. The mean μ and standard deviation σ of the existing data will be calculated. Based on production experience, it is assumed that the correlation coefficients between workpieces of normal quality and those of abnormal quality both follow a normal distribution, denoted as follows: And has μ a >μ b Let p be the threshold for the corrected correlation coefficient. Then there are two cases:

[0098] 1) When μ a -3σ a ≥μ b +3σ b When the correlation coefficients of normal and abnormal workpieces do not overlap, let:

[0099]

[0100] This refers to the threshold value of the correlation coefficient between workpieces with normal quality and workpieces with abnormal quality.

[0101] 2) When μ a -3σ a <μ b +3σ b When the correlation coefficient of a workpiece with normal quality falls within (p, μ) a +3σ a) range, or when the correlation coefficient of the workpiece with abnormal quality falls within (μ b -3σ b , p), the system can make a correct judgment, that is, the probability of correctly discriminating the quality of the workpiece is:

[0102]

[0103] In the above formula, X a represents the random variable corresponding to the correlation coefficient of the workpiece with normal quality, and X b represents the random variable corresponding to the correlation coefficient of the workpiece with abnormal quality, μ a represents the average value of the correlation coefficients of the workpieces with normal quality, μ b represents the average value of the correlation coefficients of the workpieces with abnormal quality, σ a represents the standard deviation of the correlation coefficients of the workpieces with normal quality, and σ b represents the standard deviation of the correlation coefficients of the workpieces with abnormal quality.

[0104] At this time, by using the standard normal distribution table to traverse and calculate in the interval (μ a -3σ a , μ b +3σ b ), the p value corresponding to P(A) = P(A) max can be obtained as the new Spearman correlation coefficient threshold. In addition, according to the tolerances of the two situations of "abnormal-quality workpieces being judged as normal" and "normal-quality workpieces being judged as abnormal" in actual production, a weight coefficient can be set, that is, let P(A) = K a P(X a >p) + K b P(X b <p) to calculate and obtain the p value to match the process conditions with different yields.

[0105] In summary, the welding quality monitoring method of the embodiment of the present application normalizes the main factors related to the seam welding quality to the dynamic resistance in the seam welding process, extracts the original data by calculating the average value; uses the Spearman correlation coefficient to measure the similarity of the average dynamic resistance sequences of adjacent workpieces in time as the feature for anomaly detection; infers the distribution of the Spearman correlation coefficients of normal workpieces and abnormal workpieces as a normal distribution, and uses its characteristics to adopt a simple method to calculate and update the threshold of quality classification.

[0106] Therefore, the differences between the embodiment of the present application and the prior art are:

[0107] 1) Variable polarity transistor power supply and its application scheme for device package seam welding; The embodiments of this application adopt a capacitor energy storage + transistor H-bridge output stage to design a variable polarity power supply suitable for resistance welding process; The power supply scheme is applied to the device package seam welding scenario, which provides higher control accuracy and time resolution to accurately control heat compared with other power supply schemes, and adds bidirectional current output to balance the formation of double weld seams, which is a new solution for device package seam welding.

[0108] 2) Implementation plan for online quality monitoring of seam welding in device packaging; In the absence of research and specific solutions for quality monitoring in this welding scenario, the embodiments of this application simplify and abstract the seam welding process, select dynamic resistance as the original data for quality evaluation, use the Spearman correlation coefficient of adjacent workpieces as features, and utilize the universal normal distribution and its features to achieve self-correction of the anomaly detection threshold. The method includes a complete quality monitoring process of process analysis, feature extraction and classification, with low computational load, and can be deployed to the embedded platform on which the welding power supply is mounted.

[0109] It is understood that the content of the above method embodiments is applicable to this power supply embodiment. The specific functions implemented in this power supply embodiment are the same as those in the above method embodiments, and the beneficial effects achieved are also the same as those achieved in the above method embodiments.

[0110] The preferred embodiments of the present application have been described above with reference to the accompanying drawings, but this does not limit the scope of the claims of the present application. Any modifications, equivalent substitutions, and improvements made by those skilled in the art without departing from the scope and substance of the embodiments of the present application shall be within the scope of the claims of the present application.

Claims

1. A variable polarity seam bonding power supply for device packaging, characterized in that, The variable polarity seam welding power supply includes a power main circuit module and a control system module. The power main circuit module includes a power input module, a power conversion module, an energy storage capacitor bank module, an H-bridge chopper module, and an output module. The output terminal of the control system module is connected to the H-bridge chopper module of the power main circuit module, and the output module of the power main circuit module is connected to the input terminal of the control system module. The power main circuit module is used to provide welding current to the output module; The control system module is used to control the operation of the variable polarity seam welding power supply. The main power circuit module includes a power input module, a power conversion module, an energy storage capacitor bank module, an H-bridge chopper module, and an output module. The output terminal of the power input module is connected to the input terminal of the power conversion module, the output terminal of the power conversion module is connected to the input terminal of the energy storage capacitor bank module, the output terminal of the energy storage capacitor bank module is connected to the input terminal of the H-bridge chopper module, and the output terminal of the H-bridge chopper module is connected to the input terminal of the output module. The power input module is used to obtain power input from the power grid; The power conversion module is used to convert the power input into AC / DC power; The energy storage capacitor bank module is used to receive the DC power input and store it in the form of electrical energy. The H-bridge chopper module is used to control the output of the electrical energy to generate welding current; The output module is used to output the welding current to the device packaging workpiece.

2. The variable polarity seam welding power source according to claim 1, characterized in that, The H-bridge chopper module includes a first MOSFET, a second MOSFET, a third MOSFET, a fourth MOSFET, a first welding cable inductor, and a second welding cable inductor. The first MOSFET includes a first parasitic diode, the second MOSFET includes a second parasitic diode, the third MOSFET includes a third parasitic diode, and the fourth MOSFET includes a fourth parasitic diode. The drains of the first MOS transistor and the second MOS transistor are both connected to the positive terminal of the energy storage capacitor bank module; The source of the first MOSFET is connected to the first end of the inductor of the first welding cable, and the source of the second MOSFET is connected to the first end of the inductor of the second welding cable. The source of the third MOS transistor and the source of the fourth MOS transistor are both connected to the negative terminal of the energy storage capacitor bank module. The drain of the third MOS transistor is connected to the first end of the inductor of the first welding cable, and the drain of the fourth MOS transistor is connected to the first end of the inductor of the second welding cable. The second end of the first welding cable inductor and the second welding cable inductor are respectively connected to different ends of the device package workpiece.

3. The variable polarity seam welding power source according to claim 1, characterized in that, The control system module includes a main control chip module, a drive circuit module, a sampling module, a human-machine interaction module, a switch quantity module, a data storage module, and a data communication module. The first output terminal of the main control chip module is connected to the input terminal of the drive circuit module; the second output terminal of the main control chip module is connected to the input terminal of the human-machine interaction module; the third output terminal of the main control chip module is connected to the input terminal of the switch quantity module; the fourth output terminal of the main control chip module is connected to the input terminal of the data storage module; the fifth output terminal of the main control chip module is connected to the input terminal of the data communication module; the output terminal of the sampling module is connected to the first input terminal of the main control chip module; the output terminal of the human-machine interaction module is connected to the second input terminal of the main control chip module; the output terminal of the switch quantity module is connected to the third input terminal of the main control chip module; the output terminal of the data storage module is connected to the fourth input terminal of the main control chip module; and the output terminal of the data communication module is connected to the fifth input terminal of the main control chip module. Wherein: The main control chip module is used to control the operation of the variable polarity seam welding power supply; The drive circuit module is used to amplify the power of the PWM signal emitted by the main control chip module. The sampling module is used to perform signal conditioning processing on the output current and output voltage of the main control chip module and convert them into digital quantities. The human-computer interaction module is used to acquire welding parameters and display the current welding status; The digital input module is used to read the start signal; The data storage module is used to store welding data; The data communication module is used to exchange information with external devices.

4. A method for monitoring the welding quality of device-oriented packages using a variable polarity seam welding power source as described in any one of claims 1 to 3, characterized in that, The method includes: The variable polarity seam welding power supply is turned on to perform welding on the device package workpiece, and the average dynamic resistance sequence of the device package workpiece after welding is obtained. Based on the average dynamic resistance sequence of the device packaged workpiece after welding, the Spearman correlation coefficient of the device packaged workpiece after welding is determined. Set a threshold for the Spearman correlation coefficient to determine the quality of the device packaged components after soldering; If the Spearman correlation coefficient is less than the Spearman correlation coefficient threshold, then the quality of the device packaged workpiece after welding is unqualified. If the Spearman correlation coefficient is greater than the Spearman correlation coefficient threshold, then the quality of the device packaged workpiece after welding is qualified.

5. The method according to claim 4, characterized in that, The step of connecting the variable polarity seam welding power supply to perform welding processing on the device package workpiece and obtaining the average dynamic resistance sequence of the device package workpiece after welding includes: The electrode lifespan of the variable polarity seam welding process for device packaging is specified according to actual requirements. During the electrode lifecycle of the aforementioned variable polarity seam welding process for device packaging, the device packaging workpiece is welded. The data storage module of the variable polarity seam welding power supply reads the pulse current data and pulse voltage data of the device packaged workpiece after welding. The pulse current data and the pulse voltage data of a preset proportion are selected and their arithmetic average is calculated to obtain the average dynamic resistance sequence of the device packaged workpiece after welding.

6. The method according to claim 5, characterized in that, The specific expression for calculating the arithmetic mean is shown below: In the above formula, This indicates the solder joint number of a specific component in the device package. This indicates the number of pulse current or voltage data points corresponding to the solder joint with serial number m. This indicates the sequence number of the pulse current or voltage data point corresponding to the solder joint. This indicates calculating the average value. This indicates the serial number of the packaged workpiece for a certain device. The solder joints, for which pulse current or voltage data is obtained. indivual Calculate the average value.

7. The method according to claim 4, characterized in that, The determination of the Spearman correlation coefficient of the device packaged workpiece after welding, based on the average dynamic resistance sequence of the workpiece after welding, includes: The average dynamic resistance sequence of the device packaged workpiece after welding is converted to obtain a two-dimensional average dynamic resistance sequence. The two-dimensional average dynamic resistance sequence is selected and sorted according to the first value of each element to construct a first index number; The second value of each element after sorting the two-dimensional average dynamic resistance sequence is selected to construct the second index number; Extract all the second index numbers to obtain an index array; The Spearman correlation coefficient is calculated on the index array to determine the Spearman correlation coefficient of the device packaged workpiece after welding.

8. The method according to claim 7, characterized in that, The specific expression for calculating the Spearman correlation coefficient is as follows: In the above formula, This represents the Spearman correlation coefficient. Represents the first element in each element. One value, Indicates the first Individual component packaging workpiece, Indicates workpiece With workpiece The first in the dynamic resistance sequence The square of the difference between the indices of the values ​​in their respective sequences.

9. The method according to claim 4, characterized in that, It also includes a correction process for the Spearman correlation coefficient threshold, specifically including: Based on the uncorrected Spearman correlation coefficient threshold, the device package workpieces are classified as qualified and unqualified. The average value and standard deviation of the Spearman correlation coefficients for the qualified device packaging workpieces and the average value and standard deviation of the Spearman correlation coefficients for the unqualified device packaging workpieces are obtained respectively. Weighting coefficients are set based on the tolerance levels in actual production for two scenarios: a workpiece with abnormal quality is judged as normal and a workpiece with normal quality is judged as abnormal. The Spearman correlation coefficient threshold is corrected based on the mean and standard deviation and the weighting coefficient.

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