Method for welding and packaging laser array of external heat dissipation type photon passive integrated array

Abstract

The invention relates to the technical field of laser array packaging, in particular to a laser array welding and packaging method for an external heat dissipation type photon passive integrated array, which comprises the following steps: acquiring temperature data, stress data and a heat dissipation path of each monitoring point in a current welding spot area; according to the temperature data change trend of each monitoring point in the current welding spot area, a welding spot risk index is obtained in combination with the overall distribution condition of the temperature data; according to the fluctuation distribution of the temperature data of the adjacent monitoring points on the heat dissipation path and the welding spot risk index, combining the temperature difference between the current welding spot area and the surface of the radiator to obtain a heat conduction efficiency index; according to the fluctuation condition of the collaborative change of the temperature data and the stress data of each monitoring point in the current welding spot area, combining the difference condition of the stress data to obtain a coupling anomaly index; and finally, technological parameters in the laser array welding and packaging process are adjusted. According to the invention, the welding spot stability and the optical coupling precision in the welding and packaging process can be effectively improved.

Description

TECHNICAL FIELD

[0001] The present 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 photonic passive integrated array. BACKGROUND

[0002] At present, the mainstream optical chip integration platform materials, such as silicon, lithium niobate and silicon nitride, are all indirect band gap materials, which are difficult to meet the demand of high-power light on chip, so the introduction of III-V materials into the photonic integration platform becomes the research focus; but III-V materials, especially InP materials, will generate a lot of heat during light emission, and when integrated on a silicon photonic chip, it is very easy to reach saturation without additional heat dissipation structure, thereby reducing the light emission efficiency and reducing the wall plug efficiency.

[0003] The welding process itself needs a relatively high temperature to realize the firm combination of the chip and the substrate, which will further aggravate the local heat accumulation of the laser; on the other hand, the traditional packaging method mainly depends on passive heat dissipation devices (such as metal bottom plate or external heat sink), the heat dissipation path is long, the thermal resistance is large, and it is difficult to meet the heat dissipation demand of high-power density laser array. Due to the uneven distribution of thermal stress, it is easy to cause chip offset, welding point failure or packaging structure deformation, thereby reducing the optical coupling precision and device life. Therefore, the welding parameters with fixed values are adopted in the prior art, which cannot adapt to the local heat accumulation of the welding points in the welding process, so that the welding effect is poor. SUMMARY

[0004] In order to solve the technical problem that the welding parameters with fixed values are adopted in the prior art, which cannot adapt to the local heat accumulation of the welding points in the welding process, so that the welding effect is poor, the purpose of the present application is to provide a laser array welding packaging method of an external heat dissipation type photonic passive integrated array, and the technical scheme adopted is as follows: In the current monitoring time window, the temperature data and stress data of the current welding point area in the laser array at different monitoring points are obtained, and the heat dissipation path between the current welding point area and the heat sink is obtained. According to the change trend of the temperature data of each monitoring point in the current welding point area at each time, and the overall distribution of the temperature data of different monitoring points at the same time, the welding point risk index of the current welding point area is obtained. According to the fluctuation distribution of the temperature data of the adjacent monitoring points on the heat dissipation path in the time window and the welding point risk index, and the temperature difference between the current welding point area and the surface of the heat sink, the heat conduction efficiency index is obtained. According to the fluctuation of the temperature data and the stress data of each monitoring point in the current welding point area at the same time, and the difference of the stress data of different monitoring points at the same time, a coupling abnormal index between the thermal stress and the deformation is obtained. According to the heat dissipation efficiency index and the coupling abnormal index, the process parameters in the laser array welding packaging process are adjusted.

[0005] Preferably, the welding point risk index of the current welding point area is obtained according to the change trend of the temperature data of each monitoring point in the current welding point area at each time, and the overall distribution of the temperature data of different monitoring points at the same time, specifically including: Based on the temperature data of the same monitoring point in the current welding point area within a time window, a temperature fitting curve of each monitoring point is constructed; the temperature data of all monitoring points of the current welding point area at each time within the time window is constructed into a temperature distribution sequence at each time; According to the change trend of the temperature fitting curve of each monitoring point and the temperature distribution difference between adjacent time points, a thermal accumulation characteristic value of the current welding point area is obtained. Based on the ratio between the information amount of the temperature distribution sequence at each time and the information amount of the temperature distribution sequence of the adjacent previous time, an uneven characteristic value of the current welding point area is determined. The welding point risk index of the current welding point area is determined according to the thermal accumulation characteristic value and the uneven characteristic value, and the thermal accumulation characteristic value and the uneven characteristic value are positively correlated with the welding point risk index.

[0006] Preferably, the welding point risk index of the current welding point area is obtained according to the change trend of the temperature fitting curve of each monitoring point and the temperature distribution difference between adjacent time points, specifically including: The range of the temperature data in the temperature distribution sequence at each time is obtained as the temperature range value at each time; Based on the ratio between the temperature range values between each time and the adjacent previous time, a first distribution coefficient is determined; the average slope of the temperature fitting curves of all monitoring points is taken as a second distribution coefficient; the product of the first distribution coefficient and the second distribution coefficient is the thermal accumulation characteristic value of the current welding point area.

[0007] Preferably, the heat dissipation efficiency index is obtained according to the fluctuation distribution of the temperature data of adjacent monitoring points on the heat dissipation path within a time window, and the welding point risk index, in combination with the temperature difference between the current welding point area and the surface of the heat sink, specifically including: According to the fluctuation of the temperature fitting curves of adjacent monitoring points on the heat dissipation path, in combination with the welding point risk index of the current welding point area, a heat conduction stability factor is obtained. According to the difference between the temperature data of all monitoring points of the current solder joint area at each time and the temperature data of the surface of the heat sink, and in combination with the heat conduction stability factor, a heat conduction efficiency index is obtained.

[0008] Preferably, the heat conduction stability factor is obtained according to the fluctuation of the temperature fitting curve of the adjacent monitoring points on the heat dissipation path, in combination with the solder joint risk index of the current solder joint area, and specifically includes: Based on the ratio between the fluctuation coefficients of the temperature fitting curves of each monitoring point and the adjacent next monitoring point on the heat dissipation path, the heat conduction coefficient of the heat dissipation path is determined. The product between the negative correlation coefficient of the solder joint risk index of the current solder joint area and the heat conduction coefficient is taken as the heat conduction stability factor.

[0009] Preferably, the heat conduction efficiency index is obtained according to the difference between the temperature data of all monitoring points of the current solder joint area at each time and the temperature data of the surface of the heat sink, in combination with the heat conduction stability factor, and specifically includes: The temperature mean value of the temperature data of all monitoring points at each time in the current solder joint area is obtained. Based on the difference between the temperature mean value at each time of the current solder joint area and the temperature data of the surface of the heat sink, the heat dissipation temperature difference is determined. The product between the heat conduction stability factor and the negative correlation coefficient of the heat dissipation temperature difference is taken as the heat conduction efficiency index.

[0010] Preferably, the coupling abnormal index between thermal stress and deformation is obtained according to the fluctuation of the cooperative change of the temperature data and the stress data of each monitoring point in the current solder joint area at the same time, in combination with the difference of the stress data of different monitoring points at the same time, and specifically includes: According to the fluctuation of the cooperative change of the temperature data and the stress data of each monitoring point in the current solder joint area at the same time, a first abnormal coefficient is obtained. According to the difference of the stress data between each two monitoring points of the current solder joint area at the same time, a second abnormal coefficient is obtained. The product of the first abnormal coefficient and the second abnormal coefficient is taken as the coupling abnormal index between stress and deformation.

[0011] Preferably, the first abnormal coefficient is obtained according to the fluctuation of the cooperative change of the temperature data and the stress data of each monitoring point in the current solder joint area at the same time, and specifically includes: The ratio between each two adjacent stress difference values and temperature difference values of each monitoring point is taken as each cooperative data value of each monitoring point. The variance of the rate of change of all cooperative data values of each monitoring point over time is accumulated to obtain the first abnormal coefficient.

[0012] Preferably, the second abnormality coefficient is obtained according to the difference of stress data between each two monitoring points of the current welding spot area at the same time, and specifically comprises: The absolute value of the difference between the stress data of each two different monitoring points at each time is obtained to obtain each stress difference value at each time; and the mean value of all stress difference values at all times is taken as the second abnormality coefficient.

[0013] Preferably, the process parameters in the laser array welding packaging process are adjusted according to the heat conduction efficiency index and the coupling abnormality index, and specifically comprises: The Euclidean norm between the negative correlation coefficient of the heat conduction efficiency index and the normalized value of the coupling abnormality index is normalized to obtain a guidance factor; and the power in the laser array welding packaging process is reduced by using the guidance factor.

[0014] The embodiments of the present application have at least the following beneficial effects: The present application firstly selects the temperature data and stress data of the welding process in the current monitoring time window to provide a data basis for the subsequent feature analysis process. Then, the heat accumulation of the current welding spot area is evaluated according to the temperature change of the corresponding monitoring point at each monitoring position and the change of the temperature gradient in the current welding spot area, and the welding spot risk degree of the current welding spot area is further obtained by combining the temperature distribution of the current welding spot area with the change of time; secondly, the heat conduction stability in the current welding process is analyzed according to the temperature fluctuation between adjacent monitoring points in the heat dissipation path and the welding spot risk degree, and the heat dissipation efficiency of the heat sink in the current welding process is evaluated by combining the difference between the temperature of the current welding spot area and the temperature of the heat sink; further, the response relationship between the detected temperature change and the strain change in the welding process is analyzed, the coupling state between the thermal-mechanical deformation is analyzed, and finally the guidance factor in the welding packaging process is obtained by combining the evaluated heat dissipation efficiency of the heat sink, so as to optimize the related process parameters, effectively improve the welding spot stability and the optical coupling precision in the welding packaging process, and improve the welding effect of the laser array. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, and the advantages thereof, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without any creative effort.

[0016] Figure 1 is a step flow chart of the laser array welding packaging method of the external heat dissipation type photon passive integrated array provided by the present application; Figure 2 is a structural schematic diagram of the external heat dissipation type photonic passive integrated array provided by the present application; Figure 3 is another structural schematic diagram of the external heat dissipation type photonic passive integrated array provided by the present application; Figure 4 is a structural schematic diagram of the heat dissipation integrated laser array provided by the present application; Figure 5 is a step flowchart of the method for obtaining the solder joint risk index of the current solder joint area provided by the present application; Figure 6 is a step flowchart of the method for obtaining the heat conduction efficiency index provided by the present application; wherein, Figures 2-4 the reference sign of the drawing is: 1, substrate layer, 2, insulating layer, 3, waveguide array, 4, metal layer, 5, heat dissipation integrated laser array, 51, heat dissipation heat sink, 52, laser. DETAILED DESCRIPTION

[0017] In order to further illustrate the technical means and effects taken by the present application to achieve the predetermined invention purpose, the following describes the laser array soldering packaging method of the external heat dissipation type photonic passive integrated array according to the present application, its specific implementation, structure, features and effects in detail in combination with the drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics in one or more embodiments can be combined in any suitable form.

[0018] 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 the present application belongs.

[0019] The specific scheme of the laser array soldering packaging method of the external heat dissipation type photonic passive integrated array provided by the present application is described in detail below in combination with the drawings.

[0020] Please refer to Figure 1 which shows the step flowchart of the laser array soldering packaging method of the external heat dissipation type photonic passive integrated array provided by one embodiment of the present application, which includes the following steps: Step S100, in the current monitoring time window, the temperature data and stress data of the current solder joint area in the laser array at different monitoring points are obtained, as well as the heat dissipation path between the current solder joint area and the heat sink.

[0021] The current welding point area refers to the area of a welding point being welded by the laser array. Temperature sensors and stress sensors are arranged at different positions in the current welding point area to collect temperature data and stress data of corresponding monitoring points at each position in the current welding point area in real time. It should be noted that the temperature data and stress data in the embodiment are standardized data to avoid the influence of different dimensions on the data analysis process. The data is standardized, and details are not repeated here.

[0022] The heat dissipation path refers to the complete path of heat generated in the welding point area to the external heat sink. A plurality of monitoring points are arranged on the heat dissipation path, and a temperature sensor is arranged at the position of each monitoring point to collect temperature data and analyze the heat dissipation on the heat dissipation path corresponding to the single welding point area in the laser array welding process.

[0023] The current monitoring time window represents the time window of the temperature stable heating stage, and the time length is 30 seconds. The implementer can set it according to the specific implementation scene. More specifically, by monitoring the change rate of temperature data at each time, when the change rate at a certain time is less than the preset change threshold, it indicates that the temperature data change is relatively stable at this time, and it is in the temperature stable heating stage. A time window of 30 seconds from this time is used for feature analysis of the embodiment.

[0024] The change rate at each time can be calculated by the difference between the temperature data at this time and the adjacent previous time changing with the time difference. This is a known technology, and details are not repeated here. The value of the change threshold needs to be set by the relevant staff according to the specific implementation scene.

[0025] It should be noted that the welding process usually includes a transient heating stage and a stable heating stage. In the transient heating stage, the surface temperature usually rises rapidly because the welding heat source just contacts the chip. The rapid temperature rise in the welding moment is inevitable and belongs to the normal heat input response, which has limited reference value for process optimization. The temperature and heat in the stable heating maintenance stage reach a relatively stable state. At this time, the local heat accumulation, thermal gradient and thermal stress distribution have shown the real performance difference of the material, welding point structure and heat dissipation path. In other embodiments, the stable heating stage can also be continuously monitored for each time window through system marking.

[0026] As a specific example, the embodiment gives a specific structure diagram of an external heat dissipation type photon passive integrated array, as shown in Figure 2 and Figure 3 It includes a substrate layer 1, an insulating layer 2, a waveguide array 3, a metal layer 4, and a heat-dissipatable integrated laser array 5.

[0027] The substrate layer 1 has a groove on one side; the insulating layer 2 is arranged on the substrate layer 1 and has the same area as the substrate layer 1; the waveguide array 3 is arranged on the insulating layer 2 and is connected to the groove and located on one side of the groove; the metal layer 4 is arranged in the groove of the substrate layer 1 and on the substrate layer 1; the heat-dissipating integrated laser array 5 is located on the metal layer 4 and serves as an on-chip light source; the heat-dissipating integrated laser array 5 is aligned with the waveguide array 3 and inputs laser into the waveguide array 3. The metal layer 4 is imaged into an array, each small block has an area less than or equal to the area of a single laser, and the thickness of the metal layer 4 enables the flip-chip heat-dissipating integrated laser array 5 to be highly aligned with the waveguide array 3, and simultaneously serves as a dielectric medium to provide electrical driving for the heat-dissipating integrated laser array 5.

[0028] As shown in Figure 4 The heat-dissipating integrated laser array 5 is composed of a heat sink 51 and a laser 52. The laser array is packaged on the heat sink 51 by a normal mounting method through indium-tin solder, the pitch of the laser array is the same as that of the waveguide array 3, and the front cavity of the laser 52 is flush. The heat-dissipating integrated laser array 5 is aligned and bonded with the metal layer 4 by flip-chip mounting, the positive electrode is led out by the metal layer 4, and the negative electrode is the heat sink.

[0029] The contact interface between the bottom of a single laser (which belongs to the laser 52) and a single block of the array in the metal layer 4. The interface is bonded by indium-tin solder and is the core node of electrical signal transmission (the metal layer 4 provides electrical driving for the laser) and initial heat conduction (heat generated by the laser is transmitted to the metal layer). The metal layer 4 is imaged into an array, each small block has an area less than or equal to the area of a single laser, so the single soldering point area is completely overlapped with the solder coverage area of a single block of the array.

[0030] The heat dissipation path refers to the complete path of heat generated by the soldering point area to the external heat sink, which is the soldering point area, the metal layer 4 (each soldering point area corresponds to a solder coverage area), the substrate layer 1, and the external heat sink (including the heat sink 51 for auxiliary heat conduction), and is the key transmission link of heat from the heat source (laser) to the heat dissipation terminal.

[0031] More specifically, for a soldering point area, there is a heat dissipation path from the soldering point to a single block of the metal layer, to a local part of the substrate layer, and to the heat sink, forming a matching relationship of one soldering point and one path, avoiding interference between heat of different soldering point areas in the heat dissipation path, and 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 soldering point area, the center point of the solder coverage area of a single block of the metal layer, and the position of the substrate layer on the same straight line as the two center points. In other embodiments, according to different implementation scenarios, the corresponding heat dissipation path is different, and different monitoring points can be set on the heat dissipation path in the direction from the soldering point area to the heat sink.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] Specifically, for any one monitoring point in the current solder joint area, the temperature data of the monitoring point at all time points in the time window is fitted to obtain the temperature fitting curve of the monitoring point. The data fitting method can use the least square method, which will not be described here.

[0039] For any one time point in the time window, the temperature data of all monitoring points in the current solder joint area forms a temperature distribution sequence at the corresponding time point. It should be understood that the temperature data at the corresponding position in the temperature distribution sequence at each time point belongs to the same monitoring point, that is, the arrangement of the temperature data in the temperature distribution sequences at different time points is the same. The temperature distribution sequence at each time point represents the temperature distribution of different monitoring points at the same time.

[0040] Step S202, according to the change trend of the temperature fitting curve of each monitoring point and the temperature distribution difference between the temperature distribution sequences of adjacent time points, the heat accumulation characteristic value of the current solder joint area is obtained.

[0041] In the first aspect, the heat accumulation degree of the current solder joint area is evaluated mainly from the coupling relationship between the temperature change trend and the temperature unevenness degree.

[0042] Specifically, the range of the temperature data in the temperature distribution sequence at each time point is obtained as the temperature range value at each time point; the ratio of the temperature range values between each time point and the adjacent previous time point is used to determine the first distribution coefficient; 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.

[0043] It should be understood that on the temperature fitting curve of any one monitoring point, first the average value of the slope values corresponding to all data points, and then the average value of the average slope values corresponding to all monitoring points is calculated to obtain the average slope, that is, the second distribution coefficient. The calculation method of the slope value of a single data point on the fitting curve is a known technology, which will not be described here.

[0044] As a specific example, the heat accumulation characteristic value of the current solder joint can be represented by the formula: wherein, represents the heat accumulation characteristic value of the current solder joint, represents the second distribution coefficient, that is, the average slope of the temperature fitting curves of all monitoring points, represents the number of time points contained in the current monitoring time window; represents the temperature range value at the i+1th moment, that is, the difference between the maximum value and the minimum value of the temperature data in the temperature distribution sequence at the i+1th moment. represents the temperature range value at the i+1th moment, that is, the difference between the maximum value and the minimum value of the temperature data in the temperature distribution sequence at the i+1th moment. is the first distribution coefficient.

[0045] is the second distribution coefficient. represents the balance of the temperature change trend of all the monitoring points in the time window, and the greater the value, the more the current solder region continues to heat up and the heat continues to accumulate in the local range. The temperature range value represents the temperature distribution size range of the current solder region at a moment, and the greater the value, the more uneven the temperature distribution of the current solder region at the corresponding moment. The ratio between the temperature distribution ranges of adjacent moments reflects the ratio change of the temperature difference with time, and the greater the ratio, the more the temperature difference gradually increases and the spatial thermal gradient gradually expands.

[0046] Further, the greater the value of the product , the more obvious the local heating trend of the current solder region in the current monitoring time window, and the more the spatial non-uniformity continues to increase, and the greater the value of the corresponding heat accumulation feature value.

[0047] In step S203, the non-uniform feature value of the current solder region is determined based on the ratio between the information amount of the temperature distribution sequence at each moment and the information amount of the temperature distribution sequence at the adjacent previous moment.

[0048] As a specific example, first, the information entropy of the temperature distribution sequence at each moment is calculated, which reflects the information amount of the temperature distribution in the temperature distribution sequence at the corresponding moment, and essentially represents the non-uniformity degree of the temperature distribution at the corresponding moment.

[0049] When the temperatures of all the monitoring points in the current solder region are relatively close, the discrete degree of the temperature data is low, the uncertainty is small, and the value of the information entropy of the temperature distribution sequence at the corresponding moment is smaller. When the temperature difference of all the monitoring points in the current solder region is significant, the discrete degree of the temperature data is high, the uncertainty is large, and the value of the information entropy of the temperature distribution sequence at the corresponding moment is greater. Further, in this embodiment, the information entropy is used to quantify the non-uniformity degree of the temperature distribution of all the monitoring points in the current solder region at each moment.

[0050] Further, first, the ratio between the information entropies of the temperature distribution sequences of adjacent two moments is calculated , and then the average value of all the ratios an uneven characteristic value of the current solder region, wherein, an information entropy of the temperature distribution sequence at the i+1th moment, an information entropy of the temperature distribution sequence at the ith moment.

[0051] reflects the change of the temperature uniformity characteristic with time, and the greater the value, the greater the temperature unevenness characteristic in the current solder region continues to increase with time, and the greater the possibility of local heat accumulation.

[0052] Step S204, determining a solder risk index of the current solder region according to the heat accumulation characteristic value and the uneven characteristic value, both of which are positively correlated with the solder risk index.

[0053] Specifically, the product of the heat accumulation characteristic value and the uneven characteristic value is taken as the solder risk index of the current solder region. 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 solder region, but also local unevenness, and thus it indicates that the solder has a high risk degree at this time, and at this time, the heat dissipation in the welding process should be focused on.

[0054] Step S300, obtaining a heat conduction efficiency index according to the fluctuation distribution of the temperature data of the adjacent monitoring points on the heat dissipation path within the time window and the solder risk index, and combining the temperature difference between the current solder region and the surface of the heat sink.

[0055] The purpose of this step is to further observe the heat conduction state in the heat dissipation path to analyze the transmission efficiency and balance of heat between the chip, the solder, the substrate and the external heat sink, so as to locate the thermal resistance bottleneck and realize targeted optimization of the welding process parameters and the packaging structure.

[0056] In the first aspect, the solder risk index quantifies the heat accumulation degree of the current solder region and the local risk of the solder, and further needs to measure the source of the risk. If the heat accumulation of the current solder region exceeds the standard, it may be that there is a thermal resistance bottleneck in the heat dissipation path (such as poor contact between the metal layer and the substrate layer), or the heat dissipation device itself may have insufficient heat conduction capacity. In order to locate the core problem in the heat conduction process, it is necessary to analyze the stability of the heat transfer path from the solder to the heat sink, that is, whether each layer of the heat dissipation path can continuously and uniformly conduct heat to avoid the aggravation of heat accumulation due to local heat fluctuation. Therefore, the heat conduction stability characteristic analysis process is introduced, the attenuation law of temperature fluctuation in the heat dissipation path is quantified, and it is judged whether the heat conduction process is smooth, which provides a basis for subsequent positioning of the thermal resistance bottleneck. The specific analysis process is shown in the following step S301.

[0057] In a second aspect, the actual heat dissipation capacity of the heat sink is further quantified. For example, the temperature fluctuation of a certain heat dissipation path decays quickly, but the temperature difference between the solder joint and the heat sink is always large, indicating that the heat sink can stably conduct heat, but cannot efficiently absorb and dissipate heat, which still leads to heat accumulation in the soldering area. To evaluate the characteristic performance of the absolute heat dissipation capacity, the heat dissipation efficiency of the heat sink is introduced in this embodiment, which comprehensively judges whether the heat sink can timely take away the heat of the solder joint area to avoid thermal failure by combining the heat conduction stability and the temperature difference between the solder joint and the heat sink. The specific analysis process is shown in the following step S302.

[0058] To this end, as shown in Figure 6 , the heat dissipation efficiency index can be obtained by steps S301 and S302.

[0059] In step S301, a heat conduction stability factor is obtained according to the fluctuation of the temperature fitting curve of adjacent monitoring points on the heat dissipation path, combined with the solder joint risk index of the current solder joint area.

[0060] Specifically, in the first step, the heat conduction 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 adjacent next monitoring point on the heat dissipation path.

[0061] In this embodiment, the variance is used to measure the fluctuation degree of the temperature data. More specifically, the variance of all temperature data on the temperature fitting curve of each monitoring point is taken as the fluctuation coefficient, which represents the temperature fluctuation degree at the position of the corresponding monitoring point. Further, the ratio between the fluctuation coefficients of each monitoring point and the adjacent next monitoring point on the heat dissipation path from the current solder joint area to the heat sink is calculated . This ratio focuses on the dissipation capacity of heat conduction in the heat dissipation channel. The larger the ratio, the more the temperature fluctuation amplitude gradually decays when heat is transferred from the solder joint to the heat sink (more stable near the heat sink), indicating that the heat conduction dissipation capacity is strong. The smaller the ratio, the larger the fluctuation amplitude, indicating that there is local interference in the heat dissipation path (such as poor contact leading to interruption and then recovery of heat conduction), and the heat conduction stability is poor.

[0062] Further, the average of all ratios is taken as the heat conduction coefficient of the heat dissipation path, reflecting the overall fluctuation decay level of the entire heat dissipation system. Wherein, represents the fluctuation coefficient corresponding to the xth monitoring point on the heat dissipation path, represents the fluctuation coefficient corresponding to the x+1th monitoring point on the heat dissipation path.

[0063] In the second step, the product between the negative correlation coefficient of the solder joint risk index of the current solder joint area and the heat conduction coefficient is taken as the heat conduction stability factor.

[0064] If the risk of the welding point itself is high (heat accumulation is serious), even if the path fluctuation attenuation ratio is high, the overall heat conduction may still be in an unstable state. Therefore, as a specific example, the calculation formula of the heat conduction stability factor may be expressed as: wherein, represents the welding point risk index of the current welding point area, represents the heat conduction coefficient of the heat dissipation path, represents the exponential function with the natural constant e as the base.

[0065] The greater the value of the heat conduction stability factor , the lower the risk of the welding point, and the stronger the path fluctuation attenuation, and the more stable the heat conduction process. The smaller the value of the heat conduction stability factor , the higher the risk of the welding point, or there is a thermal resistance bottleneck in the path, and the connection problem of the heat dissipation path can be prioritized.

[0066] In step S302, the heat conduction efficiency index is obtained according to the difference between the temperature data of all monitoring points of the current welding point area at each time and the temperature data of the surface of the heat sink, combined with the heat conduction stability factor.

[0067] The heat conduction stability factor measures the heat conduction stability and the stability of the fluctuation on the heat dissipation path through the attenuation of the temperature fluctuation on the heat dissipation path. On this basis, considering that if a path has a very fast fluctuation variance attenuation, but the overall heat flow may still be small, resulting in ineffective elimination of heat accumulation, the temperature difference between the current welding point area and the heat sink is further analyzed to evaluate the absolute heat conduction capacity.

[0068] First, the temperature mean value of the temperature data of all monitoring points of the current welding point area at each time is obtained.

[0069] It should be understood that for the current welding point area, one time corresponds to one temperature mean value. In the embodiment, there is a center point of the monitoring point on the surface of the heat sink, that is, for the surface of the heat sink, one time corresponds to one temperature data. In other embodiments, if multiple monitoring points are set on the surface of the heat sink to monitor temperature changes, it should be understood that the temperature mean value can also be used to obtain one temperature characteristic performance of the surface of the heat sink at one time.

[0070] Second, based on the difference between the temperature mean value of the current welding point area at each time and the temperature data of the surface of the heat sink, the heat dissipation temperature difference is determined, and the product of the negative correlation coefficient between the heat conduction stability factor and the heat dissipation temperature difference is taken as the heat conduction efficiency index.

[0071] As a specific example, the absolute value of the difference between the temperature mean value of the current solder region at each time and the temperature data of the heat sink surface at the same time is calculated, and then the mean value of the absolute value of the difference at all times is taken as the heat dissipation temperature difference at each time.

[0072] The heat dissipation temperature difference reflects the balance degree of the temperature difference between the current solder region and the heat sink at adjacent times. The smaller the value is, the faster the heat can be conducted along the heat dissipation path to the heat sink, and the higher the heat dissipation efficiency is. Then, the product of the negative correlation coefficient between the heat conduction stability factor and the heat dissipation temperature difference quantifies the heat conduction efficiency index. The larger the product is, the more it indicates that the heat dissipation path of the welding temperature is unobstructed and the heat sink can timely absorb the heat, and then it indicates that the heat conduction efficiency of the heat sink in the current welding process is high.

[0073] At this point, the heat conduction efficiency index corresponding to the current solder region represents the ability of heat conduction from the solder core to the heat sink along the heat dissipation path in the current welding process.

[0074] Step S400, according to the fluctuation of the temperature data and the stress data of each monitoring point in the current solder region at the same time, and combining the difference of the stress data of different monitoring points at the same time, the coupling abnormal index between thermal stress and deformation is obtained.

[0075] In the welding process, local temperature rise will cause material thermal expansion. If the heat dissipation is uneven or the heat conduction efficiency is low, non-uniform thermal stress will be generated. It is necessary to further evaluate the thermal stress distribution and potential deformation risk of the welding structure to guide the welding process optimization and packaging reliability design.

[0076] The main purpose of this step is to analyze the coupling state between the thermal stress generated by welding and the deformation of the mechanism in the welding process. Through coupling analysis, the micro deformation trend in the welding process can be quantified, and process or structure compensation measures can be taken to ensure the relative position accuracy of the chip in the array, thereby improving the optical coupling efficiency.

[0077] Specifically, in the first step, according to the fluctuation of the temperature data and the stress data of each monitoring point in the current solder region at the same time, a first abnormal coefficient is obtained.

[0078] More specifically, the ratio between each two adjacent stress difference and temperature difference of each monitoring point is taken as each collaborative data value of each monitoring point; the variance of the rate of change of all collaborative data values of each monitoring point with time is accumulated to obtain the first abnormal coefficient.

[0079] ​As a specific example, taking any one monitoring point as an example, the difference value of the temperature data is calculated to obtain the temperature difference value, the difference value between the stress data is calculated to obtain the stress difference value, and then the ratio between the stress difference value and the temperature difference value is taken as the cooperative data value. It should be understood that each two adjacent time points correspond to a cooperative data value, which reflects the sensitivity of local thermal stress to structural response. The larger the ratio, the more significant the strain change caused by unit temperature change, and the more intense the thermal-mechanical response.

[0080] Then, for the monitoring point, all the cooperative data values are arranged in time sequence, the slope value of the adjacent two cooperative data values is calculated, and then the variance of the slope values of all the adjacent two cooperative data values is taken as the abnormal factor of the monitoring point. The average of the abnormal factors of all the monitoring points is the first abnormal coefficient.

[0081] The calculation method of the slope value is a known technology, for example, the slope value can be obtained by calculating the ratio of the difference value between the adjacent two cooperative data values and the corresponding time interval, which reflects the dynamic change rate of the thermal stress response sensitivity. The larger the slope value, the more intense the fluctuation of the sensitivity with time, and the more unstable the thermal-mechanical coupling state.

[0082] Further, the abnormal factor of each monitoring point quantifies the fluctuation degree of the thermal stress response sensitivity with time, judges the stability of the thermal-mechanical coupling state, and finally quantifies the stability balance of all the monitoring points in the current solder point area in the form of average value.

[0083] The second step is to obtain the second abnormal coefficient according to the difference between the stress data of each two monitoring points in the current solder point area at the same time.

[0084] Specifically, the absolute value of the difference between the stress data of each two different monitoring points at each time is obtained to obtain each stress difference value at each time; and the average of all the stress difference values at all times is taken as the second abnormal coefficient.

[0085] It should be understood that at the same time, the current solder point area contains multiple monitoring points, and each two different monitoring points correspond to a stress difference value, which reflects the difference in stress distribution at different positions at the same time node. The second abnormal coefficient reflects the balance of the stress difference distribution between different positions in the current solder point area, and can measure the consistency of the overall structure deformation. The larger the value of the second abnormal coefficient, the greater the degree of uneven stress distribution and inconsistent structure response.

[0086] The third step is to take the product of the first abnormal coefficient and the second abnormal coefficient as the coupling abnormal index between stress and deformation.

[0087] Finally, by combining the feature analysis results from both aspects, the coupling feature analysis results of the current solder joint area are quantified.

[0088] 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.

[0089] Step S500: Adjust the process parameters of the laser array welding and packaging process according to the thermal conductivity index and coupling anomaly index.

[0090] 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.

[0091] 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.

[0092] 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: 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).

[0093] 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. represents the thermal stress-mechanism deformation coupling, which represents the mechanical coordination of the structure; then the fusion result is greater, the more obvious the abnormal contradiction of the heat dissipation bottleneck and the coupling is, prompting the need to adjust the process parameters, such as reducing the welding heating rate, welding power and the like, to reduce the abnormal performance in this regard. The smaller the fusion result is, the better the heat dissipation effect is, and the structure is relatively stable, and the coupling abnormality is smaller, and thus the degree of adjustment is smaller, that is, the process parameters can be fine-tuned.

[0094] When the value of the guide factor is greater, the corresponding process parameter needs to be reduced by a greater amplitude, and in the embodiment, the adjustment process of the laser power is taken as an example for description. When the value of the guide factor is smaller, the corresponding process parameter needs to be reduced by a smaller amplitude.

[0095] It should be understood that the preset laser power is the actual power originally operated in the welding process, which can be directly obtained by the welding system, and will not be described in detail here. Finally, after obtaining the adjusted laser power, the welding system is input to complete the welding adjustment.

[0096] 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 parameter. As a specific example, after the power adjustment coefficient is added, the adjusted laser power can be represented as: Wherein, L is the power adjustment coefficient, which can be set to 0.1-0.2, which essentially represents the maximum power reduction ratio corresponding to a unit guide factor. For example, when L=0.2, it means that when the highest risk , the maximum power reduction is 20%, which not only avoids the risk of being unable to alleviate the risk due to the small reduction, but also prevents welding failure due to the large reduction, which is a verified safe adjustment threshold.

[0097] It should be further noted that in other embodiments, the welding process after power adjustment can also be continuously monitored, and the same method of the present application can be used to collect various data, calculate relevant indicators, and update the guide factor value. When the updated guide factor is less than the updated guide factor, it means that the process parameter adjustment is effective, the risk is reduced, and the current adjusted process parameter If the updated guide factor is greater than the updated guide factor, it means that the adjustment operation has not alleviated the risk, and the relevant staff can be notified to perform troubleshooting operations on the welding process of the laser array, and the like.

[0098] In summary, the application first selects a short observation window in the stable heating and maintaining stage of the welding process, evaluates the heat accumulation index of the current solder region according to the temperature change at each monitoring position and the change of the temperature gradient in the current solder region, then obtains the risk degree of the solder in the welding process in combination with the phenomenon that whether the temperature gradient of the current solder region as a whole changes synchronously with time, then analyzes the variance trend of the temperature fluctuation amplitude between the adjacent layer monitoring points in the heat dissipation path to calculate the heat conduction stability in the current welding process, evaluates the heat dissipation efficiency of the heat sink in the current welding process in combination with the difference between the temperature of the current solder region and the temperature of the heat sink, then analyzes the response relationship between the detected temperature change and the strain change in the welding process, analyzes the coupling state between the thermal-mechanical deformation, and finally obtains the guidance factor in the welding packaging process in combination with the evaluated heat dissipation efficiency of the heat sink, optimizes the related process parameters, so as to effectively improve the solder stability and the optical coupling precision in the welding packaging process.

[0099] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A method of laser array solder packaging for an externally cooled photonic passive integrated array, characterized by, The method comprises the following steps: In the current monitoring time window, the temperature data and stress data of the current solder joint area in the laser array at different monitoring points, and the heat dissipation path between the current solder joint area and the heat sink are obtained; According to the change trend of the temperature data of each monitoring point in the current solder joint area at each time, and the overall distribution of the temperature data of different monitoring points at the same time, the solder joint risk index of the current solder joint area is obtained; According to the fluctuation distribution of the temperature data of the adjacent monitoring points on the heat dissipation path in the time window and the solder joint risk index, and the temperature difference between the current solder joint area and the heat sink surface, the heat conduction efficiency index is obtained; According to the fluctuation of the temperature data and stress data of each monitoring point in the current solder joint area at the same time, and the difference of the stress data of different monitoring points at the same time, the coupling abnormal index between thermal stress and deformation is obtained; According to the heat conduction efficiency index and the coupling abnormal index, the process parameters in the laser array welding packaging process are adjusted.

2. The laser array die bonding method of the externally heat-sinking photonic passive integrated array according to claim 1, wherein, According to the change trend of the temperature data of each monitoring point in the current solder joint area at each time, and the overall distribution of the temperature data of different monitoring points at the same time, the solder joint risk index of the current solder joint area is obtained, specifically including: Based on the temperature data of the same monitoring point in the current solder joint area in the time window, the temperature fitting curve of each monitoring point is constructed; the temperature data of all monitoring points of the current solder joint area at each time in the time window is constructed to form a temperature distribution sequence at each time; According to the change trend of the temperature fitting curve of each monitoring point and the temperature distribution difference between adjacent time distribution sequences, the thermal accumulation characteristic value of the current solder joint area is obtained; Based on the ratio between the information amount of the temperature distribution sequence at each time and the information amount of the temperature distribution sequence of the adjacent previous time, the uneven characteristic value of the current solder joint area is determined; According to the thermal accumulation characteristic value and the uneven characteristic value, the solder joint risk index of the current solder joint area is determined, and the thermal accumulation characteristic value and the uneven characteristic value are positively correlated with the solder joint risk index.

3. The laser array die bonding method of the externally heat-sinking photonic passive integrated array according to claim 1, wherein, According to the change trend of the temperature fitting curve of each monitoring point and the temperature distribution difference between adjacent time distribution sequences, the thermal accumulation characteristic value of the current solder joint area is obtained, specifically including: The range of the temperature data in the temperature distribution sequence at each time is obtained as the temperature range value at each time; Based on the ratio of the temperature range values between each time and the adjacent previous time, a first distribution coefficient is determined; the average slope of the temperature fitting curve of all monitoring points is taken as a second distribution coefficient; the product of the first distribution coefficient and the second distribution coefficient is the thermal accumulation characteristic value of the current solder joint area.

4. The laser array die bonding method of the externally heat-sinking photonic passive integrated array according to claim 2, wherein, According to the fluctuation of the temperature fitting curve of the adjacent monitoring points on the heat dissipation path, and the solder joint risk index of the current solder joint area, a heat conduction stability factor is obtained; ​ According to the difference between the temperature data of all monitoring points of the current solder joint area at each time and the temperature data of the surface of the heat sink, and in combination with the heat conduction stability factor, a heat conduction efficiency index is obtained.

5. The laser array soldering packaging method of the external heat dissipation type photonic passive integration array according to claim 4, characterized in that, The heat conduction stability factor is obtained according to the fluctuation of the temperature fitting curve of adjacent monitoring points on the heat dissipation path, in combination with the solder joint risk index of the current solder joint area, and specifically includes: Based on the ratio between the fluctuation coefficients of the temperature fitting curves of each monitoring point and the adjacent next monitoring point on the heat dissipation path, the heat conduction coefficient of the heat dissipation path is determined. The product of the negative correlation coefficient of the solder joint risk index of the current solder joint area and the heat conduction coefficient is taken as the heat conduction stability factor.

6. The laser array die bonding method of the externally heat-sinking photonic passive integrated array according to claim 4, wherein, The heat conduction efficiency index is obtained according to the difference between the temperature data of all monitoring points of the current solder joint area at each time and the temperature data of the surface of the heat sink, in combination with the heat conduction stability factor, and specifically includes: The temperature mean value of the temperature data of all monitoring points at each time in the current solder joint area is obtained. Based on the difference between the temperature mean value of the current solder joint area at each time and the temperature data of the surface of the heat sink, the heat dissipation temperature difference is determined. The product of the heat conduction stability factor and the negative correlation coefficient of the heat dissipation temperature difference is taken as the heat conduction efficiency index.

7. The laser array die bonding method of the externally heat-sinking photonic passive integrated array according to claim 1, wherein, The coupling abnormal index between thermal stress and deformation is obtained according to the fluctuation of the cooperative change of the temperature data and the stress data of each monitoring point in the current solder joint area at the same time, in combination with the difference of the stress data of different monitoring points at the same time, and specifically includes: A first abnormal coefficient is obtained according to the fluctuation of the cooperative change of the temperature data and the stress data of each monitoring point in the current solder joint area at the same time. A second abnormal coefficient is obtained according to the difference of the stress data between each two monitoring points of the current solder joint area at the same time. The product of the first abnormal coefficient and the second abnormal coefficient is taken as the coupling abnormal index between stress and deformation.

8. The laser array soldering packaging method of the external heat dissipation type photonic passive integration array according to claim 7, characterized in that, The first abnormal coefficient is obtained according to the fluctuation of the cooperative change of the temperature data and the stress data of each monitoring point in the current solder joint area at the same time, and specifically includes: The ratio between each two adjacent stress difference values and temperature difference values of each monitoring point is taken as each cooperative data value of each monitoring point. The first abnormal coefficient is obtained by accumulating and averaging the variance of the rate of change of all cooperative data values of each monitoring point over time.

9. The laser array soldering packaging method of the external heat dissipation type photonic passive integration array according to claim 7, characterized in that, The second abnormal coefficient is obtained according to the difference of the stress data between each two monitoring points of the current solder joint area at the same time, and specifically includes: The absolute value of the difference of the stress data between each two different monitoring points at each time is obtained to obtain each stress difference value at each time. The mean value of all stress difference values at all times is taken as the second abnormal coefficient.

10. The laser array soldering package method of the externally heat-sinking photonic passive integrated array according to claim 1, wherein, The process parameters in the laser array soldering packaging process are adjusted according to the heat conduction efficiency index and the coupling abnormal index, and specifically include: The Euclidean norm between the negative correlation coefficient of the heat conduction efficiency index and the normalized value of the coupling abnormal index is normalized to obtain a guidance factor. The guidance factor is used to reduce the power in the laser array soldering packaging process.

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