Laser array solder package method for externally cooled photonic passive integrated array

Abstract

The application relates to the technical field of laser array packaging, in particular to a laser array welding packaging method of an external heat dissipation type photon passive integrated array, which comprises the following steps: acquiring temperature data and stress data of each monitoring point in a current welding point area and a heat dissipation path; obtaining a welding point risk index according to a temperature data change trend of each monitoring point in the current welding point area and in combination with overall distribution of the temperature data; obtaining a heat conduction efficiency index according to fluctuation distribution of temperature data of adjacent monitoring points on the heat dissipation path and in combination with a temperature difference between the current welding point area and a radiator surface; obtaining a coupling abnormality index according to fluctuation of the temperature data and the stress data of each monitoring point in the current welding point area in coordination with difference of the stress data; and finally adjusting process parameters in a laser array welding packaging process. The application can effectively improve welding point stability and optical coupling precision in the welding packaging process.

Description

Technical Field

[0001] This invention relates to the field of laser array packaging technology, and more specifically to a laser array welding and packaging method for an externally heat-dissipating passive photonic integrated array. Background Technology

[0002] Currently, mainstream optical chip integration platform materials, such as silicon, lithium niobate, and silicon nitride, are all indirect bandgap materials, which are difficult to meet the requirements of high-power light on the chip. Therefore, introducing III-V materials into photonic integration platforms has become a research focus. However, III-V materials, especially InP materials, generate a lot of heat during the light emission process. When integrated on photonic chips such as silicon, they are very easy to reach saturation without additional heat dissipation, thereby reducing luminous efficiency and wall insertion efficiency.

[0003] The welding process itself requires high temperatures to achieve a firm bond between the chip and the substrate, which further exacerbates localized heat accumulation in the laser. On the other hand, traditional packaging methods often rely on passive heat dissipation devices (such as metal substrates or external heat sinks), resulting in long heat dissipation paths and high thermal resistance, making it difficult to meet the heat dissipation requirements of high-power-density laser arrays. Uneven distribution of thermal stress can easily cause chip misalignment, solder joint failure, or package structure deformation, thereby reducing optical coupling accuracy and device lifespan. Therefore, the use of fixed welding parameters in existing technologies cannot adapt to the localized heat accumulation at weld points during the welding process, resulting in poor welding performance. Summary of the Invention

[0004] To address the problem that existing technologies using fixed welding parameters cannot adapt to the heat accumulation at local welding points during the welding process, resulting in poor welding performance, the present invention aims to provide a laser array welding and packaging method for an externally heat-dissipating photonic passive integrated array. The specific technical solution adopted is as follows:

[0005] Within the current monitoring time window, acquire temperature and stress data of the current solder joint area in the laser array at different monitoring points, as well as the heat dissipation path between the current solder joint area and the heat sink.

[0006] Based on the temperature data change trend of each monitoring point in the current welding area at each time, and combined with the overall distribution of temperature data of different monitoring points at the same time, the welding risk index of the current welding area is obtained.

[0007] Based on the temperature fluctuation distribution of adjacent monitoring points on the heat dissipation path within the time window and the solder joint risk index, combined with the temperature difference between the current solder joint area and the heat sink surface, the thermal conductivity index is obtained.

[0008] Based on the fluctuation of temperature and stress data at each monitoring point within the current weld joint area at the same time, and combined with the differences in stress data at different monitoring points at the same time, an abnormal coupling index between thermal stress and deformation is obtained.

[0009] Based on the thermal conductivity and coupling anomaly indices, the process parameters for laser array welding and packaging are adjusted.

[0010] Preferably, the step of obtaining the weld joint risk index of the current weld joint area based on the temperature data change trend of each monitoring point in the current weld joint area at each time moment, combined with the overall distribution of temperature data of different monitoring points at the same time moment, specifically includes:

[0011] Based on the temperature data of the same monitoring point within the current welding point area within the time window, a temperature fitting curve for each monitoring point is constructed; the temperature data of all monitoring points within the current welding point area at each moment within the time window are used to construct a temperature distribution sequence for each moment.

[0012] Based on the changing trend of the temperature fitting curve at each monitoring point and the temperature distribution difference between adjacent time intervals, the heat accumulation characteristic value of the current welding point area is obtained.

[0013] Based on the ratio between the information content of the temperature distribution sequence at each time moment and the information content of the temperature distribution sequence at the adjacent previous time moment, the non-uniformity characteristic value of the current solder joint region is determined.

[0014] The solder joint risk index of the current solder joint area is determined based on the heat accumulation characteristic value and the non-uniformity characteristic value. Both the heat accumulation characteristic value and the non-uniformity characteristic value are positively correlated with the solder joint risk index.

[0015] Preferably, obtaining the thermal accumulation characteristic value of the current solder joint area based on the changing trend of the temperature fitting curve of each monitoring point and the temperature distribution difference between adjacent time-series temperatures specifically includes:

[0016] The range of temperature data in the temperature distribution sequence at each time point is obtained as the temperature range value at each time point;

[0017] The first distribution coefficient is determined based on the ratio of the temperature range values ​​between each time point and the adjacent previous time point; the average slope of the temperature fitting curves of all monitoring points is used as the second distribution coefficient; the product of the first distribution coefficient and the second distribution coefficient is the heat accumulation characteristic value of the current solder joint area.

[0018] Preferably, the step of obtaining the thermal conductivity index based on the temperature fluctuation distribution of adjacent monitoring points on the heat dissipation path within a time window and the solder joint risk index, combined with the temperature difference between the current solder joint area and the radiator surface, specifically includes:

[0019] Based on the fluctuation of the temperature fitting curves of adjacent monitoring points along the heat dissipation path, and combined with the solder joint risk index of the current solder joint area, a heat conduction stability factor is obtained.

[0020] Based on the difference between the temperature data of all monitoring points in the current solder joint area at each moment and the temperature data of the radiator surface, and combined with the heat conduction stability factor, the thermal conductivity efficiency index is obtained.

[0021] Preferably, the step of obtaining the heat conduction stability factor based on the fluctuation of the temperature fitting curves of adjacent monitoring points along the heat dissipation path, combined with the solder joint risk index of the current solder joint area, specifically includes:

[0022] The thermal conductivity coefficient of the heat dissipation path is determined based on the ratio between the fluctuation coefficients of the temperature fitting curves of each monitoring point and the next adjacent monitoring point on the heat dissipation path.

[0023] The product of the negative correlation coefficient of the solder joint risk index in the current solder joint area and the thermal conductivity coefficient is used as the thermal conductivity stability factor.

[0024] Preferably, the step of obtaining the thermal conductivity efficiency index based on the difference between the temperature data of all monitoring points in the current solder joint area at each moment and the temperature data of the radiator surface, combined with the thermal conductivity stability factor, specifically includes:

[0025] Obtain the average temperature of all monitoring points in the current weld area at each time point;

[0026] The heat dissipation temperature difference is determined based on the difference between the average temperature of the current solder joint area at each time point and the temperature data of the heat sink surface.

[0027] The product of the thermal conductivity stability factor and the negative correlation coefficient between the heat dissipation temperature difference is used as the thermal conductivity efficiency index.

[0028] Preferably, the step of obtaining the coupling anomaly index between thermal stress and deformation based on the fluctuation of temperature and stress data at each monitoring point within the current weld joint area at the same time, combined with the differences in stress data at different monitoring points at the same time, specifically includes:

[0029] The first anomaly coefficient is obtained based on the fluctuation of temperature and stress data at each monitoring point within the current weld joint area at the same time.

[0030] The second anomaly coefficient is obtained based on the difference in stress data between every two monitoring points in the current weld area at the same time.

[0031] The product of the first anomaly coefficient and the second anomaly coefficient is used as the coupling anomaly index between stress and deformation.

[0032] Preferably, the step of obtaining the first anomaly coefficient based on the fluctuation of temperature and stress data at each monitoring point within the current weld joint area at the same time specifically includes:

[0033] The ratio between the stress difference and temperature difference between any two adjacent monitoring points is obtained as each collaborative data value for each monitoring point; the variance of the rate of change of all collaborative data values ​​for each monitoring point over time is accumulated and averaged to obtain the first anomaly coefficient.

[0034] Preferably, the step of obtaining the second anomaly coefficient based on the difference in stress data between every two monitoring points in the current weld area at the same time specifically includes:

[0035] The absolute value of the difference in stress data between every two different monitoring points at each time moment is obtained to obtain the stress difference value at each time moment; the mean of all stress difference values ​​at all times moment is used as the second anomaly coefficient.

[0036] Preferably, adjusting the process parameters during the laser array welding and packaging process based on thermal conductivity and coupling anomaly indices specifically includes:

[0037] The Euclidean norm between the negative correlation coefficient of the thermal conductivity index and the normalized value of the coupling anomaly index is normalized to obtain a guidance factor; the power in the laser array welding and packaging process is reduced using the guidance factor.

[0038] The embodiments of the present invention have at least the following beneficial effects:

[0039] This invention first selects temperature and stress data within the current monitoring time window of the welding process to provide a data foundation for subsequent feature analysis. Then, based on the temperature changes at each monitoring point and the temperature gradient changes in the current weld joint area, the heat accumulation in the current weld joint area is assessed. Furthermore, the overall temperature distribution of the current weld joint area over time is combined to determine the weld joint risk level. Next, the heat conduction stability during the current welding process is analyzed based on temperature fluctuations between adjacent monitoring points in the heat dissipation path and the weld joint risk level. The heat sink thermal conductivity efficiency during the current welding process is assessed by combining the temperature difference between the current weld joint area and the heat sink temperature. Further, the response relationship between detected temperature changes and strain changes during the welding process is analyzed, and the coupling state between thermo-mechanical deformation is analyzed. Finally, the assessed heat sink thermal conductivity efficiency is combined to obtain a guiding factor for the welding and packaging process, optimizing relevant process parameters to effectively improve weld joint stability and optical coupling accuracy during the welding and packaging process, thereby enhancing the welding effect of the laser array. Attached Figure Description

[0040] To more clearly illustrate the technical solutions and advantages 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a flowchart of the laser array welding and packaging method for an externally heat-dissipating passive photonic integrated array provided by the present invention.

[0042] Figure 2 This is a schematic diagram of the structure of the external heat dissipation passive photonic integrated array provided by the present invention;

[0043] Figure 3 This is another structural schematic diagram of the externally heat-dissipating passive photonic integrated array provided by the present invention;

[0044] Figure 4 This is a schematic diagram of the structure of the heat-dissipating integrated laser array provided by the present invention;

[0045] Figure 5 This is a flowchart of the steps for obtaining the solder joint risk index of the current solder joint area provided by the present invention;

[0046] Figure 6 This is a flowchart of the steps for obtaining the thermal conductivity index provided by the present invention;

[0047] in, Figure 2-4The reference numerals in the attached figures are: 1, substrate layer; 2, insulating layer; 3, waveguide array; 4, metal layer; 5, heat-dissipating integrated laser array; 51, heat dissipation element; 52, laser. Detailed Implementation

[0048] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of the laser array welding and packaging method for an externally heat-dissipating passive photonic integrated array proposed by the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0049] 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 invention pertains.

[0050] The following describes in detail, with reference to the accompanying drawings, the specific scheme of the laser array welding and packaging method of the external heat dissipation photonic passive integrated array provided by the present invention.

[0051] Please see Figure 1 The diagram illustrates a step-by-step flowchart of a laser array welding and packaging method for an externally heat-dissipating passive photonic integrated array according to an embodiment of the present invention. The method includes the following steps:

[0052] Step S100: Within the current monitoring time window, acquire the temperature and stress data of the current solder joint area at different monitoring points in the laser array, as well as the heat dissipation path between the current solder joint area and the heat sink.

[0053] The current solder joint area refers to the area where a solder joint is being welded by the laser array. Temperature sensors and stress sensors are set at several different locations within the current solder joint area to collect temperature and stress data at each monitoring point in real time. It should be noted that the temperature and stress data in this embodiment are standardized data to avoid the influence of different dimensions on the data analysis process. The standardization of the data is not described in detail here.

[0054] The heat dissipation path refers to the complete path through which the heat generated in the solder joint area is transferred to the external heat sink. Several monitoring points are set up along the heat dissipation path, and a temperature sensor is set up at each monitoring point to collect temperature data and analyze the heat dissipation situation on the heat dissipation path corresponding to a single solder joint area during the laser array welding process.

[0055] The current monitoring time window represents the time window for maintaining a stable temperature heating phase, with a duration of 30 seconds. Implementers can set this according to specific implementation scenarios. More specifically, by monitoring the rate of change of temperature data at each moment, when the rate of change at a certain moment is less than a preset threshold, it indicates that the temperature data is relatively stable and in a stable heating phase. The 30-second period starting from that moment constitutes a time window for feature analysis in this embodiment.

[0056] The rate of change at each moment can be calculated by the difference between the temperature data at that moment and the temperature data at the adjacent previous moment as the time difference changes. This is a well-known technique and will not be elaborated on here. The value of the change threshold needs to be set by relevant personnel according to the specific implementation scenario.

[0057] It should be noted that the soldering process typically includes a transient heating phase and a stable heating phase. During the transient heating phase, the surface temperature usually rises rapidly upon initial contact with the heat source, a phenomenon that is inevitable and a normal thermal input response, offering limited reference value for process optimization. In contrast, the stable heating phase maintains a relatively stable temperature and heat output. At this point, localized heat accumulation, thermal gradients, and thermal stress distribution reveal the true performance differences in materials, solder joint structures, and heat dissipation paths. In other embodiments, continuous monitoring can be performed for each time window after the stable heating phase is initiated by system marking.

[0058] As a specific example, this embodiment provides a schematic diagram of the structure of an externally heat-dissipating passive photonic integrated array, such as... Figure 2 and Figure 3 As shown, it includes a substrate layer 1, an insulating layer 2, a waveguide array 3, a metal layer 4, and a heat-dissipating integrated laser array 5.

[0059] A groove is located on one side of substrate 1; an insulating layer 2 is disposed on substrate 1, with the same area as substrate 1; a waveguide array 3 is disposed on insulating layer 2, connected to the groove, and located on one side of the groove; a metal layer 4 is disposed within the groove of substrate 1 on substrate 1; a heat-dissipating integrated laser array 5 is located on metal layer 4, serving as an on-chip light source. The heat-dissipating integrated laser array 5 is aligned with waveguide array 3, and laser light is input into waveguide array 3. The metal layer 4 is imaged as an array, with each small piece having an area less than or equal to that of a single laser. The thickness of the metal layer 4 allows for high alignment between the flip-chip heat-dissipating integrated laser array 5 and waveguide array 3, while also serving as a dielectric to provide electrical drive for the heat-dissipating integrated laser array 5.

[0060] like Figure 4As shown, the heat-dissipating integrated laser array 5 consists of a heat dissipation radiator 51 and a laser 52. The laser array is mounted on the heat dissipation radiator 51 by indium tin solder in a positive mounting manner. The spacing of the laser array is the same as that of the waveguide array 3, and the front cavity of the laser 52 is flush with the waveguide array 3. The heat-dissipating integrated laser array 5 uses flip-chip bonding to align and bond the laser 52 to the metal layer 4. Its positive electrode is led out from the metal layer 4, and its negative electrode is the heat dissipation radiator.

[0061] The contact interface between the bottom of a single laser (belonging to laser 52) and a single array block in metal layer 4 is bonded by indium tin solder. This interface is the core node for electrical signal transmission (metal layer 4 provides electrical drive for the laser) and initial heat conduction (heat generated by the laser is transferred to the metal layer). Metal layer 4 is imaged as an array, with each small block having an area less than or equal to that of a single laser. Therefore, the area of ​​a single solder joint is the solder-covered area that completely overlaps with the single array block of the metal layer.

[0062] The heat dissipation path refers to the complete path through which the heat generated in the solder joint area is transferred to the external heat sink. It consists of the solder joint area, metal layer 4 (each solder joint area corresponds to the solder coverage area), substrate layer 1, and external heat sink (including heat dissipation radiator 51 for auxiliary heat conduction). It is the key transmission link for heat from the heat source (laser) to the heat dissipation terminal.

[0063] More specifically, each solder joint area corresponds to a separate heat dissipation path, from solder joint → single metal layer → local substrate → heat sink, forming a one-path-one-solder-joint relationship. This avoids heat interference between different solder joint areas within the heat dissipation path, ensuring the independence and accuracy of heat conduction. It should be noted that the monitoring points on the heat dissipation path include the center point of the solder joint area, the center point of the solder-covered area of ​​the corresponding single metal layer, and the location of the substrate layer on the same straight line as these two center points. In other embodiments, depending on the implementation scenario, the corresponding heat dissipation path may differ; different monitoring points can be set along the heat dissipation path according to the direction from the solder joint area to the heat sink.

[0064] The heat sink, or external heat dissipation device, is in direct contact with the substrate layer 1 or the heat sink 51. It is the terminal heat absorption and dissipation unit of the heat dissipation path. It needs to dissipate the heat transferred from the solder joint area through efficient heat conduction to reduce the heat accumulation of the laser array.

[0065] Step S200: Based on the temperature data change trend of each monitoring point in the current solder joint area at each time, and combined with the overall distribution of temperature data of different monitoring points at the same time, obtain the solder joint risk index of the current solder joint area.

[0066] Firstly, during the welding process, high-temperature heating leads to localized heat accumulation in the laser, and the characteristics of this heat accumulation differ significantly across different heating stages. In the transient heating stage, the surface temperature rises rapidly upon initial contact with the chip, which is a normal thermal input response and has limited value for process optimization. In the stable heating maintenance stage, temperature and heat flow reach a relatively stable state. At this point, localized heat accumulation, thermal gradients, and thermal stress distribution reveal the true performance differences in materials, solder joint structures, and heat dissipation paths. To clarify the degree of heat accumulation in the welding area during this stage and identify potential overheating areas and areas of concentrated thermal stress, a heat accumulation index needs to be introduced. By quantifying the coupling relationship between temperature change trends and temperature non-uniformity, this provides a basis for subsequent heat dissipation design and welding parameter optimization.

[0067] Secondly, the heat accumulation index only reflects the coupled accumulation of temperature within the welding area over time and space, but it cannot directly explain how heat is converted into stress in the material structure, nor can it comprehensively assess the risks faced by the weld joint. During the welding process, the uniformity of temperature distribution changes over time. If the temperature non-uniformity continues to increase, it will lead to uneven heat distribution within the area, resulting in higher thermal stress and increasing the risk of weld joint failure. To comprehensively consider the impact of heat accumulation and temperature distribution stability on the weld joint, weld joint risk analysis needs to be introduced. By combining the heat accumulation index with changes in temperature distribution uniformity, the risks associated with the weld joint can be more accurately determined, providing a more comprehensive basis for subsequent process adjustments.

[0068] In this regard, such as Figure 5 As shown, the method for obtaining the solder joint risk index of the current solder joint area can be implemented by steps S201 to S204.

[0069] Step S201: Based on the temperature data of the same monitoring point within the time window in the current welding point area, construct the temperature fitting curve of each monitoring point; and construct the temperature distribution sequence of each time moment by taking the temperature data of all monitoring points in the current welding point area at each time moment within the time window.

[0070] Specifically, for any monitoring point within the current solder joint area, the temperature data of that monitoring point at all times within the time window is fitted to obtain the temperature fitting curve for that monitoring point. The data fitting method can employ the least squares method, which will not be elaborated upon here. Furthermore, the same method can be used to obtain the temperature fitting curve for each monitoring point within the current solder joint area. The temperature fitting curve characterizes the temperature change over time at the corresponding monitoring point.

[0071] For any given moment within the time window, the temperature data from all monitoring points within the current solder joint area are used to construct a temperature distribution sequence for that moment. It should be understood that the temperature data at corresponding locations within each moment's temperature distribution sequence belong to the same monitoring point; that is, the arrangement of temperature data in temperature distribution sequences at different moments is the same. Each moment's temperature distribution sequence represents the temperature distribution at different monitoring points at the same time.

[0072] Step S202: Based on the changing trend of the temperature fitting curve of each monitoring point and the temperature distribution difference between adjacent time intervals, the heat accumulation characteristic value of the current welding point area is obtained.

[0073] Firstly, the coupling relationship between the temperature change trend and the degree of temperature non-uniformity is mainly used to assess the degree of heat accumulation in the current solder joint area.

[0074] Specifically, the range of temperature data in the temperature distribution sequence at each time moment is obtained as the temperature range value at each time moment; the first distribution coefficient is determined based on the ratio of the temperature range value between each time moment and the adjacent previous time moment; the average slope of the temperature fitting curve of all monitoring points is used as the second distribution coefficient; the product of the first distribution coefficient and the second distribution coefficient is the heat accumulation characteristic value of the current solder joint area.

[0075] It should be understood that on the temperature fitting curve at any monitoring point, the average slope is obtained by first calculating the mean of the slope values ​​corresponding to all data points, and then calculating the average of the mean slope values ​​corresponding to all monitoring points. This average slope is also the second distribution coefficient. The method for calculating the slope value of a single data point on the fitting curve is a well-known technique and will not be elaborated upon here.

[0076] As a concrete example, the method for obtaining the thermal accumulation characteristic value of the current solder joint can be expressed by the formula:

[0077]

[0078] in, This represents the thermal accumulation characteristic value of the current solder joint. This represents the second distribution coefficient, which is the average slope of the temperature fitting curve for all monitoring points. This indicates the number of moments contained within the current monitoring time window; This represents the temperature range value at time i, which is the difference between the maximum and minimum values ​​of the temperature data in the temperature distribution sequence at time i. This represents the temperature range value at time i+1, which is the difference between the maximum and minimum values ​​of the temperature data in the temperature distribution sequence at time i+1. This is the first distribution coefficient.

[0079] Second distribution coefficient This indicates the equilibrium of temperature changes across all monitoring points within the time window. A larger value indicates a continuous rise in temperature in the solder joint area, with heat accumulating locally. Temperature range value This represents the range of temperature distribution in the current solder joint area at a given moment. A larger value indicates a more uneven temperature distribution in the current solder joint area at that moment. The ratio of the temperature distribution ranges at adjacent moments is used to determine the temperature distribution. The ratio reflects the relative change of temperature difference over time. The larger the ratio, the more the temperature difference gradually increases and the spatial thermal gradient gradually expands.

[0080] Furthermore, the product The larger the value of , the more obvious the local heating trend of the current solder joint area is within the current monitoring time window, and the spatial non-uniformity continues to increase. The heat accumulation characteristic will increase significantly, and the corresponding heat accumulation characteristic value will be larger.

[0081] Step S203: Based on the ratio between the information content of the temperature distribution sequence at each time moment and the information content of the temperature distribution sequence at the adjacent previous time moment, determine the non-uniformity characteristic value of the current solder joint region.

[0082] As a concrete example, we first calculate the information entropy of the temperature distribution sequence at each time point, which reflects the amount of information in the temperature distribution sequence at the corresponding time point and essentially characterizes the degree of non-uniformity of the temperature distribution at the corresponding time point.

[0083] When the temperatures of all monitoring points within the current solder joint area are relatively similar, the temperature data exhibits low dispersion and uncertainty, resulting in a smaller information entropy value for the temperature distribution sequence at the corresponding time. Conversely, when the temperatures of all monitoring points within the current solder joint area differ significantly, the temperature data exhibits high dispersion and uncertainty, leading to a larger information entropy value for the temperature distribution sequence at the corresponding time. Therefore, in this embodiment, information entropy is used to quantify the degree of non-uniformity in the temperature distribution of all monitoring points within the current solder joint area at each time.

[0084] Furthermore, the ratio of the information entropy between two adjacent time points of the temperature distribution sequence is first calculated. Then take the mean of all ratios. This serves as a non-uniform characteristic value for the current solder joint region. The information entropy represents the temperature distribution sequence at time i+1. Let entropy represent the information entropy of the temperature distribution sequence at time i.

[0085] It reflects the change of temperature uniformity characteristics over time. The larger the value, the more the temperature non-uniformity in the current solder joint area continues to increase with time, and the greater the possibility of local heat accumulation.

[0086] Step S204: Determine the solder joint risk index of the current solder joint area based on the thermal accumulation characteristic value and the non-uniformity characteristic value. The thermal accumulation characteristic value and the non-uniformity characteristic value are both positively correlated with the solder joint risk index.

[0087] Specifically, the product of the heat accumulation characteristic value and the non-uniformity characteristic value is used as the weld joint risk index for the current weld joint area. When the heat accumulation degree is high and the heat distribution stability and uniformity are poor, it indicates that there is not only local heat accumulation in the current weld joint area, but also local non-uniformity, which indicates that the weld joint has a high risk level. At this time, the heat dissipation during the welding process should be the focus of attention.

[0088] Step S300: Based on the temperature fluctuation distribution of adjacent monitoring points on the heat dissipation path within the time window and the solder joint risk index, combined with the temperature difference between the current solder joint area and the heat sink surface, the thermal conductivity index is obtained.

[0089] The purpose of this step is to further observe the heat conduction state in the heat dissipation path, in order to analyze the heat transfer efficiency and uniformity between the chip, solder joints, substrate and external heat sink, thereby locating the thermal resistance bottleneck and achieving targeted optimization of soldering process parameters and packaging structure.

[0090] Firstly, the solder joint risk index quantifies the current degree of heat accumulation and local risk in the solder joint area. Further assessment of the root causes of this risk is then necessary. If the heat accumulation in the current solder joint area exceeds the standard, it may be due to a thermal resistance bottleneck in the heat dissipation path (such as poor contact between the metal layer and the substrate layer), or it may be due to insufficient thermal conductivity of the heat sink itself. To pinpoint the core issues in the heat conduction process, it is necessary to first analyze the stability of the heat transfer path from the solder joint to the heat sink, i.e., whether each layer of the heat dissipation path can continuously and uniformly conduct heat, avoiding exacerbated heat accumulation due to local thermal fluctuations. Therefore, a heat conduction stability characteristic analysis process is introduced. By quantifying the attenuation law of temperature fluctuations in the heat dissipation path, the stability of the heat conduction process is determined, providing a basis for subsequently identifying thermal resistance bottlenecks. The specific analysis process is detailed in subsequent step S301.

[0091] Secondly, the actual thermal conductivity of the radiator is further quantified. For example, if the temperature fluctuation of a certain heat dissipation path decreases rapidly, but the temperature difference between the solder joint and the radiator remains large, it indicates that although the radiator can stably conduct heat, it cannot efficiently absorb and dissipate heat, still leading to heat accumulation in the soldering area. To evaluate the characteristic performance of absolute thermal conductivity, this embodiment introduces the radiator's thermal conductivity efficiency. By combining the thermal conduction stability with the temperature difference change between the solder joint and the radiator, a comprehensive judgment is made on whether the radiator can remove the heat from the solder joint area in time to avoid thermal failure. The specific analysis process is described in subsequent step S302.

[0092] In this regard, such as Figure 6 As shown, the method for obtaining the thermal conductivity index can be achieved through steps S301 and S302.

[0093] Step S301: Based on the fluctuation of the temperature fitting curves of adjacent monitoring points on the heat dissipation path, and combined with the solder joint risk index of the current solder joint area, the heat conduction stability factor is obtained.

[0094] Specifically, the first step is to determine the thermal conductivity of the heat dissipation path based on the ratio between the fluctuation coefficients of the temperature fitting curves of each monitoring point on the heat dissipation path and the next adjacent monitoring point.

[0095] In this embodiment, variance is used to measure the degree of temperature data fluctuation. More specifically, the variance of all temperature data on the temperature fitting curve of each monitoring point is used as the fluctuation coefficient to characterize the degree of temperature fluctuation at the location of the corresponding monitoring point. Further, along the heat dissipation path from the current solder joint area to the heat sink, the ratio of the fluctuation coefficient between each monitoring point and the next adjacent monitoring point is calculated. This ratio focuses on the heat dissipation capacity of heat conduction in the heat dissipation channel. The larger the value of this ratio, the more the temperature fluctuation amplitude gradually decreases when heat is transferred from the solder joint to the heat sink (more stable near the heat sink side), and the stronger the heat conduction dissipation capacity. The smaller the value of this ratio, the larger the fluctuation amplitude, the more local interference exists in the heat dissipation path (such as poor contact causing heat conduction to be interrupted and then restored), and the poor heat conduction stability.

[0096] Then all ratios The average value of is used as the heat transfer coefficient of the heat dissipation path, reflecting the overall fluctuation attenuation level of the entire heat dissipation system. Among them, This represents the fluctuation coefficient corresponding to the x-th monitoring point on the heat dissipation path. This represents the fluctuation coefficient corresponding to the (x+1)th monitoring point on the heat dissipation path.

[0097] The second step is to use the product of the negative correlation coefficient of the solder joint risk index of the current solder joint area and the thermal conductivity coefficient as the thermal conductivity stability factor.

[0098] If the solder joint itself has a high risk level (severe heat accumulation), even with a high path fluctuation attenuation ratio, the overall heat conduction may still be in an unstable state. Therefore, as a concrete example, the heat conduction stability factor... The calculation formula can be expressed as: ,in, This indicates the solder joint risk index for the current solder joint area. Indicates the thermal conductivity coefficient of the heat dissipation path. This represents an exponential function with the natural constant e as its base.

[0099] Thermal conductivity stability factor A higher value indicates a lower risk at the solder joint, stronger path fluctuation attenuation, and a more stable heat conduction process. Heat conduction stability factor The smaller the value, the higher the risk of the solder joint, or the presence of a thermal resistance bottleneck in the heat dissipation path. In such cases, the connection problem of the heat dissipation path should be investigated first.

[0100] Step S302: Based on the difference between the temperature data of all monitoring points in the current solder joint area at each moment and the temperature data of the heat sink surface, and combined with the heat conduction stability factor, the thermal conductivity efficiency index is obtained.

[0101] The thermal conductivity stability factor measures the stability of thermal conductivity and the stability of temperature fluctuations along the heat dissipation path by assessing the attenuation of temperature fluctuations along the path. Furthermore, considering that even if the variance of a path decays rapidly, its overall heat flux may still be small, leading to ineffective heat accumulation, the temperature difference between the solder joint area and the heat sink is further analyzed to evaluate the absolute thermal conductivity.

[0102] The first step is to obtain the average temperature of all monitoring points in the current solder joint area at each time point.

[0103] It should be understood that for the current solder joint area, there is a temperature average value at a given moment. In this embodiment, there is a monitoring point at the center of the heat sink surface, meaning that for the heat sink surface, there is a temperature data point at a given moment. In other embodiments, if multiple monitoring points are set on the heat sink surface to monitor temperature changes, it should be understood that the average temperature value can also be used to obtain a temperature characteristic of the heat sink surface at a given moment.

[0104] The second step is to determine the heat dissipation temperature difference based on the difference between the average temperature of the current solder joint area at each time and the temperature data of the heat sink surface; and to use the product of the thermal conductivity stability factor and the negative correlation coefficient of the heat dissipation temperature difference as the thermal conductivity efficiency index.

[0105] As a concrete example, the absolute value of the difference between the average temperature of the current solder joint area at each moment and the temperature data of the heat sink surface at the same moment is calculated, and then the average of the absolute values ​​of the differences at all moments is taken as the heat dissipation temperature difference at each moment.

[0106] The heat dissipation temperature difference reflects the degree of uniformity of the temperature difference between the solder joint area and the heat sink at adjacent moments. The smaller this value, the faster the heat can be conducted to the heat sink along the heat dissipation path, resulting in high heat dissipation efficiency. Therefore, the heat conduction stability factor and the heat dissipation temperature difference are used. negative correlation coefficient The product of the two values ​​quantifies the thermal conductivity index. The larger the product, the more it indicates that the heat dissipation path of the welding temperature is unobstructed and the heat sink can absorb heat in time, thus indicating that the heat sink has a high thermal conductivity in the current welding process.

[0107] Therefore, the thermal conductivity index corresponding to the current solder joint area characterizes the ability of heat from the solder joint core to the heat dissipation path during the current soldering process.

[0108] Step S400: Based on the fluctuation of temperature and stress data of each monitoring point in the current welding area at the same time, and combined with the difference of stress data of different monitoring points at the same time, the coupling anomaly index between thermal stress and deformation is obtained.

[0109] During the welding process, local temperature rise can cause thermal expansion of the material. If heat dissipation is uneven or the thermal conductivity is low, non-uniform thermal stress will be generated. Further evaluation of the thermal stress distribution and potential deformation risk of the welded structure is needed to guide the optimization of welding process and packaging reliability design.

[0110] The main purpose of this step is to analyze the coupling state between the thermal stress generated during welding and the deformation of the structure. Through coupling analysis, the micro-deformation trend during welding can be quantified, and process or structural compensation measures can be taken to ensure the relative position accuracy of the chip in the array, thereby improving the optical coupling efficiency.

[0111] Specifically, the first step is to obtain the first anomaly coefficient based on the fluctuation of temperature and stress data at each monitoring point within the current welding area at the same time.

[0112] More specifically, the ratio between the stress difference and temperature difference between any two adjacent monitoring points is obtained as each collaborative data value for each monitoring point; the variance of the rate of change of all collaborative data values ​​for each monitoring point over time is summed and averaged to obtain the first anomaly coefficient.

[0113] As a concrete example, taking any monitoring point as an example, the temperature difference is calculated between each time point and the adjacent previous time point, and the stress difference is calculated between the stress data points. Then, the ratio between the stress difference and the temperature difference is used as the co-current data value. It should be understood that there is a co-current data value between every two adjacent time points, which reflects the sensitivity of local thermal stress to the structural response. The larger the ratio, the more significant the strain change caused by a unit temperature change, and the stronger the thermo-mechanical response.

[0114] Then, for the monitoring point, all the collaborative data values ​​are arranged in time sequence, the slope value of two adjacent collaborative data values ​​is calculated, and the variance of the slope values ​​of two adjacent collaborative data values ​​is taken as the anomaly factor of the monitoring point. The mean of the anomaly factors of all monitoring points is the first anomaly coefficient.

[0115] The slope value is calculated using a known technique. For example, the slope value can be obtained by calculating the ratio of the difference between two adjacent coordinated data values ​​to the corresponding time interval. This reflects the dynamic rate of change of the thermal stress response sensitivity. The larger the slope value, the more drastic the fluctuation of the sensitivity over time, and the more unstable the thermo-mechanical coupling state.

[0116] Furthermore, the abnormal factors at each monitoring point quantify the degree of fluctuation of the thermal stress response sensitivity over time, determine the stability of the thermo-mechanical coupling state, and finally quantify the stability balance of all monitoring points in the current weld area by averaging.

[0117] The second step is to obtain the second anomaly coefficient based on the difference in stress data between every two monitoring points in the current weld area at the same time.

[0118] Specifically, the absolute value of the difference between stress data between every two different monitoring points at each time moment is obtained to obtain the stress difference value at each time moment; the mean of all stress difference values ​​at all times moment is used as the second anomaly coefficient.

[0119] It should be understood that at the same moment, the current weld joint area contains multiple monitoring points, and each pair of different monitoring points corresponds to a stress difference value, reflecting the difference in stress distribution at different locations at the same time node. The second anomaly coefficient reflects the balance of stress difference distribution at different locations in the current weld joint area, and can measure the consistency of overall structural deformation. The larger the value of the second anomaly coefficient, the greater the degree of uneven stress distribution and inconsistent structural response.

[0120] The third step is to use the product of the first and second anomaly coefficients as an index of the coupling anomaly between stress and deformation.

[0121] Finally, by combining the feature analysis results from both aspects, the coupling feature analysis results of the current solder joint area are quantified.

[0122] The larger the value of the coupling anomaly index, the worse the local response stability and global response consistency are for the current weld area. In other words, the coupling state between thermal stress and structural deformation is not good at the current stage.

[0123] Step S500: Adjust the process parameters of the laser array welding and packaging process according to the thermal conductivity index and coupling anomaly index.

[0124] By adjusting the process parameters during welding, a more stable coupling relationship between thermal stress and deformation is achieved, thereby improving the reliability of laser array packaging. The main purpose of this step is to effectively suppress adverse thermodynamic effects at the process level and improve the overall reliability of the laser array welding and packaging process by comprehensively analyzing the characteristics of both thermal conductivity efficiency and coupling anomaly indicators.

[0125] Specifically, the Euclidean norm between the negative correlation coefficient of the thermal conductivity index and the normalized value of the coupling anomaly index is normalized to obtain a guidance factor; the guidance factor is used to reduce the power in the laser array welding and packaging process.

[0126] As a concrete example, the process of adjusting the process parameters during the welding and packaging of laser arrays can be expressed by the following formula:

[0127]

[0128]

[0129] in, Indicates the guiding factor. This indicates the thermal conductivity efficiency index. Indicators of coupling anomalies This indicates the initial laser power setting. This indicates the adjusted laser power. This is the hyperbolic tangent function, used to normalize the range of values ​​to (0,1).

[0130] thermal conductivity index This indicates the heatsink's thermal conductivity during the welding process, characterizing the system's heat diffusion and conduction capabilities, and is a coupling anomaly index. This represents the coupling between thermal stress and structural deformation, characterizing the mechanical compatibility of the structure. The L2 norm is then used to fuse the results of these two aspects of the analysis. A larger fusion result indicates a more pronounced contradiction between the heat dissipation bottleneck and the coupling anomaly, suggesting the need to adjust process parameters, such as reducing the welding heating rate or welding power, to mitigate this anomaly. A smaller fusion result indicates relatively better heat dissipation and a more stable structure, with less coupling anomaly, thus requiring less adjustment—meaning only minor adjustments to process parameters are needed.

[0131] The larger the value of the guidance factor, the greater the reduction in the corresponding process parameters. In this embodiment, the adjustment process of laser power is used as an example for explanation. The smaller the value of the guidance factor, the smaller the reduction in the corresponding process parameters.

[0132] It should be understood that the preset laser power is the actual power during the initial operation of the welding process, which can be directly obtained from the welding system, and will not be elaborated further here. Finally, after obtaining the adjusted laser power, it is input into the welding system to complete the welding adjustment.

[0133] It should be noted that in other embodiments, a power adjustment coefficient can also be set to limit the maximum reduction ratio of the process parameters. As a specific example, after adding the power adjustment coefficient, the adjusted laser power can be expressed as:

[0134]

[0135] Where L is the power adjustment coefficient, which can be set from 0.1 to 0.2. Essentially, it represents the maximum power reduction percentage corresponding to a unit guidance factor. For example, when L = 0.2, it means that when the highest risk... At this time, the maximum power reduction is 20%, which avoids the risk of being unable to be mitigated due to too small a reduction, and also prevents welding failure due to too large a reduction. It is a verified safe adjustment threshold.

[0136] It should be further noted that in other embodiments, the welding process after power adjustment can be continuously monitored. Various data are collected using the same method as in this invention, relevant indicators are calculated, and the guidance factor value is updated. When the updated guidance factor is less than the previous guidance factor, it indicates that the process parameter adjustment is effective, the risk is reduced, and the current adjusted process parameters can be maintained. If the updated guidance factor is greater than the previous guidance factor, it means that the adjustment operation has not alleviated the risk. Relevant personnel can be notified to conduct troubleshooting operations on the welding process of the laser array, etc.

[0137] In summary, this invention first selects a short-term observation window during the stable heating maintenance phase of the welding process. Based on the temperature changes at each monitoring location and the temperature gradient changes in the current solder joint area, the heat accumulation index of the current solder joint area is evaluated. Then, the risk level of the solder joint during the welding process is obtained by combining the phenomenon of whether the overall temperature gradient of the current solder joint area increases synchronously over time. Next, the variance change trend of the temperature fluctuation amplitude between adjacent monitoring points in the heat dissipation path is analyzed to calculate the heat conduction stability state during the current welding process. The heat dissipation efficiency of the heat sink during the current welding process is evaluated by combining the difference between the temperature of the current solder joint area and the heat sink temperature. Then, the response relationship between the detected temperature changes and strain changes during the welding process is analyzed to analyze the coupling state between thermo-mechanical deformation. Finally, the guiding factor in the welding and packaging process is obtained by combining the evaluated heat sink heat dissipation efficiency. By optimizing relevant process parameters, the stability of the solder joint and the optical coupling accuracy during the welding and packaging process can be effectively improved.

[0138] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A laser array welding and packaging method for an externally heat-dissipating passive photonic integrated array, characterized in that, The method includes the following steps: Within the current monitoring time window, acquire temperature and stress data of the current solder joint area in the laser array at different monitoring points, as well as the heat dissipation path between the current solder joint area and the heat sink. Based on the temperature data change trend of each monitoring point in the current welding area at each time, and combined with the overall distribution of temperature data of different monitoring points at the same time, the welding risk index of the current welding area is obtained. Based on the temperature fluctuation distribution of adjacent monitoring points on the heat dissipation path within the time window and the solder joint risk index, combined with the temperature difference between the current solder joint area and the heat sink surface, the thermal conductivity index is obtained. Based on the fluctuation of temperature and stress data at each monitoring point within the current weld joint area at the same time, and combined with the differences in stress data at different monitoring points at the same time, an abnormal coupling index between thermal stress and deformation is obtained. Based on the thermal conductivity and coupling anomaly indices, the process parameters for laser array welding and packaging are adjusted. The step of obtaining the thermal conductivity index based on the temperature fluctuation distribution of adjacent monitoring points along the heat dissipation path within a time window, the solder joint risk index, and the temperature difference between the current solder joint area and the radiator surface, specifically includes: Based on the fluctuation of the temperature fitting curves of adjacent monitoring points along the heat dissipation path, and combined with the solder joint risk index of the current solder joint area, a heat conduction stability factor is obtained, including: determining the heat conduction coefficient of the heat dissipation path based on the ratio between the fluctuation coefficient of the temperature fitting curve of each monitoring point along the heat dissipation path and the next adjacent monitoring point; and using the product between the negative correlation coefficient of the solder joint risk index of the current solder joint area and the heat conduction coefficient as the heat conduction stability factor. Based on the difference between the temperature data of all monitoring points in the current solder joint area at each moment and the temperature data of the radiator surface, and combined with the heat conduction stability factor, the thermal conductivity efficiency index is obtained.

2. The laser array welding and packaging method for an externally heat-dissipating passive photonic integrated array according to claim 1, characterized in that, The process involves calculating the weld joint risk index for the current weld joint area based on the temperature data trends of each monitoring point within the current weld joint area at each time moment, combined with the overall distribution of temperature data from different monitoring points at the same time moment. Specifically, this includes: Based on the temperature data of the same monitoring point within the current welding point area within the time window, a temperature fitting curve for each monitoring point is constructed; the temperature data of all monitoring points within the current welding point area at each moment within the time window are used to construct a temperature distribution sequence for each moment. Based on the changing trend of the temperature fitting curve at each monitoring point and the temperature distribution difference between adjacent time intervals, the heat accumulation characteristic value of the current welding point area is obtained. Based on the ratio between the information content of the temperature distribution sequence at each time moment and the information content of the temperature distribution sequence at the adjacent previous time moment, the non-uniformity characteristic value of the current solder joint region is determined. The solder joint risk index of the current solder joint area is determined based on the heat accumulation characteristic value and the non-uniformity characteristic value. Both the heat accumulation characteristic value and the non-uniformity characteristic value are positively correlated with the solder joint risk index.

3. The laser array welding and packaging method for an externally heat-dissipating passive photonic integrated array according to claim 1, characterized in that, Based on the changing trend of the temperature fitting curve at each monitoring point and the temperature distribution difference between adjacent time intervals, the heat accumulation characteristic value of the current welding point area is obtained, specifically including: The range of temperature data in the temperature distribution sequence at each time point is obtained as the temperature range value at each time point; The first distribution coefficient is determined based on the ratio of the temperature range values ​​between each time point and the adjacent previous time point; the average slope of the temperature fitting curves of all monitoring points is used as the second distribution coefficient; the product of the first distribution coefficient and the second distribution coefficient is the heat accumulation characteristic value of the current solder joint area.

4. The laser array welding and packaging method for an externally heat-dissipating passive photonic integrated array according to claim 1, characterized in that, The thermal conductivity efficiency index is obtained by combining the temperature data of all monitoring points in the current solder joint area at each moment with the temperature data of the radiator surface, and the thermal conductivity stability factor. Specifically, this includes: Obtain the average temperature of all monitoring points in the current weld area at each time point; The heat dissipation temperature difference is determined based on the difference between the average temperature of the current solder joint area at each time point and the temperature data of the heat sink surface. The product of the thermal conductivity stability factor and the negative correlation coefficient between the heat dissipation temperature difference is used as the thermal conductivity efficiency index.

5. The laser array welding and packaging method for an externally heat-dissipating passive photonic integrated array according to claim 1, characterized in that, The method involves analyzing the fluctuations in temperature and stress data at each monitoring point within the current weld joint area at the same time, combined with the differences in stress data at different monitoring points at the same time, to obtain an abnormal coupling index between thermal stress and deformation. Specifically, this index includes: The first anomaly coefficient is obtained based on the fluctuation of temperature and stress data at each monitoring point within the current weld joint area at the same time. The second anomaly coefficient is obtained based on the difference in stress data between every two monitoring points in the current weld area at the same time. The product of the first anomaly coefficient and the second anomaly coefficient is used as the coupling anomaly index between stress and deformation.

6. The laser array welding and packaging method for an externally heat-dissipating passive photonic integrated array according to claim 5, characterized in that, The first anomaly coefficient is obtained based on the fluctuation of temperature and stress data at each monitoring point within the current weld joint area at the same time, specifically including: The ratio between the stress difference and temperature difference between any two adjacent monitoring points is obtained as each collaborative data value for each monitoring point; the variance of the rate of change of all collaborative data values ​​for each monitoring point over time is accumulated and averaged to obtain the first anomaly coefficient.

7. The laser array welding and packaging method for an externally heat-dissipating passive photonic integrated array according to claim 6, characterized in that, The second anomaly coefficient is obtained based on the difference in stress data between every two monitoring points in the current weld area at the same time, specifically including: The absolute value of the difference in stress data between every two different monitoring points at each time moment is obtained to obtain the stress difference value at each time moment; the mean of all stress difference values ​​at all times moment is used as the second anomaly coefficient.

8. The laser array welding and packaging method for an externally heat-dissipating passive photonic integrated array according to claim 1, characterized in that, The adjustment of process parameters during the laser array welding and packaging process based on thermal conductivity and coupling anomaly indices specifically includes: The Euclidean norm between the negative correlation coefficient of the thermal conductivity index and the normalized value of the coupling anomaly index is normalized to obtain a guidance factor; the power in the laser array welding and packaging process is reduced using the guidance factor.

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