Gradient magnesium-silicon aluminum composite electronic packaging material forming method

Abstract

The invention relates to the technical field of electronic packaging materials, and discloses a gradient magnesium-silicon-aluminum composite electronic packaging material forming method which comprises the steps of magnesium material surface treatment, first buffer layer preparation, second buffer layer preparation, composite forming and phase change material activating treatment. Wherein a nano porous Al-Cu-Mg alloy layer containing Se and Te elements is sprayed on the surface of the magnesium material, and eutectic phase and oxide particles are added in the buffer layer, so that a triple protection mechanism of thermal expansion coefficient gradient transition, phase change energy absorption and structural buffer is formed. The thermal shock resistance of the silicon-aluminum-magnesium composite electronic packaging material is improved, long-life service of the material is realized through a regeneration and activation mechanism of the phase-change material, and the reliability and stability of the composite material in a severe environment are remarkably enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic packaging materials, and more specifically, it relates to a forming method for a gradient magnesium-silicon-aluminum composite electronic packaging material. Background Art

[0002] With the rapid development of modern electronic information technology, electronic products are developing towards miniaturization, multi-function, and high performance, posing higher requirements for electronic packaging materials. As an important part of electronic devices, the performance of electronic packaging materials directly affects the reliability and lifespan of the devices.

[0003] In fields such as aviation, aerospace, and military, electronic devices often need to work under harsh environmental conditions, especially frequent thermal cycling and rapid temperature change conditions. However, the existing silicon-aluminum-magnesium composite electronic packaging materials have the following technical problems:

[0004] The difference in the thermal expansion coefficients between the silicon-aluminum alloy and the magnesium material is significant, and interface stress concentration is likely to occur under thermal cycling conditions, resulting in interface peeling failure;

[0005] When the traditional composite structure faces a rapid temperature change environment, especially when the temperature change rate exceeds 50 °C / min, the thermal shock resistance is insufficient;

[0006] During the long-term thermal cycling process of the composite material, the internal structural characteristics will decay, and the heat absorption and heat release capabilities of the phase change material will gradually decrease, limiting the service life of the material;

[0007] Conventional preparation methods are difficult to simultaneously meet the requirements of good thermal expansion coefficient transition, excellent thermal shock performance, and long service life.

[0008] Therefore, there is an urgent need to develop a forming method for a silicon-aluminum composite electronic packaging material that can simultaneously solve the above problems to meet the long-term reliable use requirements of advanced electronic devices in harsh environments. Summary of the Invention

[0009] To solve the above technical problems, the present invention provides a forming method for a gradient magnesium-silicon-aluminum composite electronic packaging material.

[0010] 2. A forming method for a gradient magnesium-silicon-aluminum composite electronic packaging material, comprising the following steps:

[0011] Step 1: Treat the surface of the magnesium material and spray a nano-porous Al-Cu-Mg alloy layer containing Se and Te elements on the surface of the magnesium material;

[0012] Step 2: Prepare a first buffer layer on the nano-porous Al-Cu-Mg alloy layer, and the first buffer layer contains a Zn-Al eutectic phase material;

[0013] Step 3: Prepare a second buffer layer on the first buffer layer, and the second buffer layer contains a Zn-Al-Mg ternary eutectic phase;

[0014] Step 4: Thermally press and compound the magnesium material and its multi-layer buffer structure with an aluminum-silicon alloy sheet to form a shape;

[0015] Step 5: After the composite formed material has served for a certain period of time, perform activation heat treatment on the material in an atmosphere of 95% Ar + 5% H2 to restore the performance of the phase change material.

[0016] Preferably: Step 1 includes:

[0017] Clean and pre-treat the surface of the magnesium material to remove the surface oxide layer and contaminants;

[0018] Using the plasma spraying process, spray an Al-Cu-Mg alloy layer on the surface of the treated magnesium material, where the Al content is 70 - 75 wt%, the Cu content is 20 - 25 wt%, and the Mg content is 3 - 5 wt%;

[0019] Place the workpiece under argon protection, keep it at a temperature of 350 - 380 °C for 1 - 2 hours, and then cool it to room temperature at a rate of 50 - 60 °C per minute to form a nano-porous structure with a porosity of 15 - 25%;

[0020] When preparing the Al-Cu-Mg alloy powder, add 1.5 - 2.5 wt% of Se and Te elements, and disperse and add 0.3 - 0.8 wt% of Y2O3 oxide particles.

[0021] Preferably: Step 2 includes:

[0022] Prepare an Al-Mg alloy powder, where the Mg content is 35 wt% and the Al content is 65 wt%;

[0023] Add 3 - 5 wt% of Zn-Al eutectic phase material to the Al-Mg alloy powder;

[0024] Use high-frequency induction to melt the Al-Mg alloy, coat the alloy melt on the surface of the treated magnesium material at a temperature of 380 - 420 °C, and control the thickness of the first buffer layer to be 0.5 - 0.8 mm;

[0025] Cool down at a cooling rate of 15 - 25 °C / min to solidify the alloy and form a bond with the substrate.

[0026] Preferably: Step 3 includes:

[0027] Prepare an Al-Mg-Si ternary alloy powder, where the Mg content is 18 wt%, the Si content is 12 wt%, and the Al content is 70 wt%.

[0028] Add 2 - 4 wt% of a Zn-Al-Mg ternary eutectic phase to the Al-Mg-Si alloy.

[0029] Adopt a high-frequency induction melting process to coat the Al-Mg-Si alloy melt on the surface of the first buffer layer, control the thickness of the second buffer layer to be 0.5 - 0.8 mm, and the coating temperature to be 400 - 450 °C.

[0030] Cool at a cooling rate of 10 - 20 °C / min to solidify the second buffer layer and form a bond with the first buffer layer.

[0031] Preferably: Step 4 includes:

[0032] Assemble the prepared magnesium material and its multi-layer buffer structure with an aluminum-silicon alloy sheet to form a layered structure to be composite, and the composition of the aluminum-silicon alloy is Al-50% Si.

[0033] Place the assembled layered structure in a hot pressing device for hot pressing and composite, the hot pressing temperature is 450 - 520 °C, and the pressure is 120 - 180 MPa.

[0034] After the hot pressing reaches the set temperature and pressure, hold for 10 - 20 minutes, and then cool at a rate of 10 - 20 °C / min.

[0035] Preferably: Step 5 includes:

[0036] When the electronic packaging material undergoes about 2000 thermal cycles, determine the activation timing by testing the endothermic enthalpy change of the phase change material by differential scanning calorimetry. When the enthalpy change value drops below 70% of the initial value, perform activation.

[0037] In an atmosphere of 95% Ar + 5% H2, perform heat treatment on the material at 350 - 400 °C for 30 minutes.

[0038] Preferably: The phase change temperature of the Zn-Al eutectic phase in the first buffer layer is 275 - 285 °C, and the phase change temperature of the Zn-Al-Mg ternary eutectic phase in the second buffer layer is 340 - 350 °C, forming a gradient phase change temperature distribution.

[0039] Preferably: The thermal expansion coefficient of the first buffer layer is 20×10 -6 / K, and the thermal expansion coefficient of the second buffer layer is 16×10 -6 / K, forming a gradual transition of the thermal expansion coefficient from the magnesium material to the aluminum-silicon alloy.

[0040] Preferably, the Se and Te elements react with Y2O3 oxide particles at a temperature of 350-400 °C, form volatile suboxides under the reduction of hydrogen, and redeposit in the eutectic phase region to repair tissue coarsening and composition segregation.

[0041] Preferably, a triple protection structure of "thermal expansion coefficient gradient transition + phase change energy absorption + structural buffer" is formed through the surface treatment of the magnesium material, the preparation of the first buffer layer, and the preparation of the second buffer layer.

[0042] The beneficial effects of the present invention are as follows: Through the triple protection mechanism of "thermal expansion coefficient gradient transition + phase change energy absorption + structural buffer", the present invention reduces the interfacial stress of the material under thermal cycling conditions. Experimental tests show that the composite material prepared by this method has no interfacial peeling phenomenon after 500 thermal cycles from -55 °C to 125 °C, while the traditional structure shows interfacial peeling after 200 thermal cycles.

[0043] Through the synergistic effect of the nanoporous structure and the phase change energy absorption material, the material can withstand a temperature change rate of more than 50 °C / min from -65 °C to 175 °C without failure, and the thermal shock resistance is 3 times that of the traditional structure.

[0044] By adopting the method of regenerating the phase change material, after the composite material undergoes more than 2000 thermal cycles, more than 90% of its initial performance can be restored through 30 minutes of heat treatment, reducing the maintenance cost and replacement frequency.

[0045] The multi-layer buffer structure solves the problem of thermal expansion coefficient matching and ensures the bonding between layers through process parameter control. The bending test shows that the interfacial tensile strength reaches more than 80 MPa, meeting the usage requirements of electronic devices.

[0046] The entire preparation process can be completed using conventional equipment, without the need for expensive devices. The activation and regeneration treatment process is simple, suitable for industrial production and on-site maintenance.

[0047] The present invention solves the problems of the silicon-aluminum-magnesium composite electronic packaging material in terms of thermal cycling stability, thermal shock resistance, and service life. In particular, the method of regenerating the phase change material provides a new way for the long-life service of electronic packaging materials and improves the reliability of electronic devices in harsh environments. Description of the Drawings

[0048] Figure 1 is the test result of the thermal cycling stability of the present invention;

[0049] Figure 2 is the test result of the thermal shock resistance of the present invention;

[0050] Figure 3 is the test result of the long-life characteristics of the present invention;

[0051] Figure 4 are the test results of the interfacial bonding strength of the present invention;

[0052] Figure 5 are the analysis results of the interfacial fracture morphology of the present invention;

[0053] Figure 6 are the test results of the process repeatability of the present invention;

[0054] Figure 7 are the test results of the equipment compatibility of the present invention;

[0055] Figure 8 are the cost analysis results of the present invention;

[0056] Figure 9 are the test results of the process robustness of the present invention;

[0057] Figure 10 are the various test results of the present invention. Detailed implementation manners

[0058] The subject matter described herein will now be discussed with reference to example embodiments. It should be understood that discussing these embodiments is only to enable those skilled in the art to better understand and thus implement the subject matter described herein, and the functions and arrangements of the elements discussed can be changed without departing from the scope of protection of the content of this specification. Each example can omit, substitute, or add various processes or components as needed. Additionally, the features described in some examples can also be combined in other examples.

[0059] In at least one embodiment of the present invention, a forming method of a gradient magnesium-silicon-aluminum composite electronic packaging material is disclosed, including the following steps:

[0060] Step 1: Surface treatment of magnesium material

[0061] Specifically, it includes:

[0062] Clean and pre-treat the surface of the magnesium material to remove the surface oxide layer and contaminants and improve the surface activity. Chemical cleaning and mechanical polishing processes are adopted.

[0063] Preparation of nano-porous Al-Cu-Mg alloy layer: Adopt the plasma spraying process to spray an Al-Cu-Mg alloy layer on the surface of the treated magnesium material, where the Al content is 70-75 wt%, the Cu content is 20-25 wt%, and the Mg content is 3-5 wt%. During the spraying process, control the plasma torch power to be 30-35 kW, the working distance to be 100-120 mm, the carrier gas to be argon, the spraying rate to be 0.5-0.8 g / s, and the substrate preheating temperature to be 150-180 °C.

[0064] Formation of nanoporous structure: After spraying is completed, the workpiece is placed under argon protection and kept at a temperature of 350 - 380 °C for 1 - 2 hours, and then cooled to room temperature at a rate of 50 - 60 °C per minute, forming a nanoporous structure with a porosity of 15 - 25%. This porous structure provides a deformation space during the thermal cycling process and reduces the interfacial stress.

[0065] Addition of functional elements: When preparing the Al - Cu - Mg alloy powder, 1.5 - 2.5 wt% of Se and Te elements are added, and 0.3 - 0.8 wt% of Y2O3 oxide particles are dispersed and added. The Se and Te elements are used for the later reactivation process of the phase change material, and the Y2O3 oxide particles act as a reaction medium to promote the formation of a local reduction environment during the regeneration process.

[0066] Basis for the selection of Se and Te elements: These two elements have a certain volatility at medium temperatures (300 - 400 °C) and can form low - melting - point compounds with various metals; while the Y2O3 oxide particles have catalytic activity at a temperature of 350 - 400 °C and can promote the reduction reaction of metal oxides. The two cooperate to form a recyclable phase change material system.

[0067] Step 2: Preparation of the first buffer layer

[0068] This step realizes the first stage of the gradual transition of the coefficient of thermal expansion and introduces the phase change energy - absorbing material, specifically including:

[0069] Alloy preparation: Prepare Al - Mg alloy powder, where the Mg content is 35 wt% and the Al content is 65 wt%. This ratio makes the coefficient of thermal expansion of the first buffer layer 20×10 -6 / K, which is between the magnesium material (26.1×10 -6 / K) and the second buffer layer, forming the first - stage transition of the coefficient of thermal expansion.

[0070] Introduction of phase change material: Add 3 - 5 wt% of Zn - Al eutectic phase material to the Al - Mg alloy powder. The phase change temperature of this eutectic phase is 275 - 285 °C, which absorbs latent heat during the rapid temperature rise, slows down the temperature change rate, and protects the interface from the impact of rapid thermal expansion.

[0071] Coating process: Use high - frequency induction to melt the Al - Mg alloy and coat the alloy melt on the surface of the treated magnesium material at a temperature of 380 - 420 °C, controlling the thickness of the first buffer layer to be 0.5 - 0.8 mm. The coating process is carried out under argon protection to prevent oxidation.

[0072] Cooling and forming: After coating, the temperature is decreased at a cooling rate of 15 - 25 °C / min to solidify the alloy and form a bond with the substrate. Control the cooling rate to ensure the interface bonding quality and tissue uniformity.

[0073] Step 3: Preparation of the second buffer layer

[0074] The second buffer layer completes the second stage of the gradual transition of the coefficient of thermal expansion and further improves the phase change energy absorption function, specifically including:

[0075] Alloy preparation: Prepare Al-Mg-Si ternary alloy powder, where the Mg content is 18 wt%, the Si content is 12 wt%, and the Al content is 70 wt%. This composition makes the coefficient of thermal expansion of the second buffer layer 16×10 -6 / K, close to the coefficient of thermal expansion of silicon-aluminum alloy (13.5×10 -6 / K), forming the second stage of the transition of the coefficient of thermal expansion.

[0076] Introduction of ternary eutectic phase: Add 2 - 4 wt% of Zn-Al-Mg ternary eutectic phase to the Al-Mg-Si alloy. The phase change temperature of this ternary eutectic phase is 340 - 350 °C, forming a gradient phase change temperature distribution with the Zn-Al eutectic phase in the first buffer layer, providing phase change energy absorption protection in a wider temperature range.

[0077] The addition of the Zn-Al-Mg ternary eutectic phase enables the material to have the ability of phase change energy absorption in the high-temperature section, cooperating with the Zn-Al eutectic phase in the first buffer layer to form a double protection effect of "low-temperature phase change protection + high-temperature phase change protection".

[0078] Coating process: Adopt the same high-frequency induction melting process as the first buffer layer, coat the Al-Mg-Si alloy melt on the surface of the first buffer layer, and control the thickness of the second buffer layer to be 0.5 - 0.8 mm. The coating temperature is 400 - 450 °C, 20 - 30 °C higher than that of the first buffer layer, to ensure interface bonding.

[0079] Cooling and forming: After coating, the temperature is decreased at a cooling rate of 10 - 20 °C / min to solidify the second buffer layer and form a bond with the first buffer layer. This cooling rate is lower than that of the first buffer layer, reducing the interface residual stress.

[0080] Step 4: Composite forming

[0081] In this step, the multi-layer buffer structure is composite formed with silicon-aluminum alloy to form the final electronic packaging material, specifically including:

[0082] Material assembly: The prepared magnesium material and its multi-layer buffer structure are assembled with the silicon-aluminum alloy sheet to form a layered structure to be compounded. The silicon-aluminum alloy has a composition of Al-50% Si, and this composition of electronic packaging material has dimensional stability and thermal conductivity.

[0083] Hot pressing and compounding: The assembled layered structure is placed in a hot pressing device for hot pressing and compounding. The hot pressing temperature is 450 - 520 °C, and the pressure is 120 - 180 MPa. This temperature and pressure range enables the full combination of each layer of materials while avoiding the melting and loss of the phase change material.

[0084] Pressure holding and cooling: After the hot pressing reaches the set temperature and pressure, it is held for 10 - 20 minutes, and then cooled at a rate of 10 - 20 °C / min. The pressure holding time affects the interfacial bonding strength, and the cooling rate affects the thermal stress to prevent interfacial cracking.

[0085] In the hot pressing and compounding process, the parameter selection of temperature, pressure, pressure holding time, and cooling rate enables it to work in cooperation with the aforementioned multi-layer buffer structure and phase change material to obtain a product with stable performance.

[0086] Step 5: Activation treatment of the phase change material

[0087] This step is used to restore the activity of the phase change material after the long-term service of the material and extend the material life, specifically including:

[0088] Determination of the activation timing: When the electronic packaging material undergoes about 2000 thermal cycles, the endothermic and exothermic capabilities of the phase change material significantly decline, and activation treatment is required. The activation timing is determined by measuring the enthalpy change of the phase change material through differential scanning calorimetry (DSC). When the enthalpy change value drops below 70% of the initial value, activation is carried out.

[0089] Atmosphere construction: The composite material to be activated is placed in an atmosphere of 95% Ar + 5% H2. In this atmosphere composition, the hydrogen content can provide a reducing environment while avoiding potential safety hazards caused by too high hydrogen concentration.

[0090] Activation heat treatment: In an atmosphere of 95% Ar + 5% H2, the material is heat-treated at 350 - 400 °C for 30 minutes. This temperature is higher than the activation temperature (300 °C) of Se and Te elements and lower than the temperature causing material structure changes (450 °C).

[0091] Activation reaction process: During the activation process, Se and Te elements react with Y2O3 oxide particles, generating a local reducing environment and element migration, and restoring the organizational structure and phase change characteristics of the eutectic phase. Under the reduction of hydrogen, Se and Te elements react with the oxide surface to form volatile suboxides, which migrate inside the material and redeposit in the eutectic phase region to repair the tissue coarsening and composition segregation caused by long-term service.

[0092] This method for regenerating the phase change material enables the material to recover more than 90% of its initial phase change energy absorption efficiency through heat treatment after undergoing more than 2,000 thermal cycles, extending the service life of the material.

[0093] Experimental verification

[0094] To verify the various technical effects of the forming method of the silicon-aluminum composite electronic packaging material of the present invention, we conducted a series of experimental tests. These experiments were aimed at objectively evaluating the performance of the materials prepared by this method in terms of thermal cycle stability, thermal shock resistance, long-life characteristics, interfacial bonding strength, and process practicability. The steps and test results of each experiment will be introduced in detail below.

[0095] I. Thermal cycle stability test

[0096] 1. Experimental purpose: To verify the interfacial stability of the composite material prepared by this method under thermal cycle conditions.

[0097] 2. Experimental steps:

[0098] Sample preparation: Prepare silicon-aluminum-magnesium composite electronic packaging material samples according to the process of Embodiment 1, with dimensions of 50 mm × 50 mm × 5 mm. At the same time, prepare control group samples according to the traditional method (without nano-porous structure and phase change material).

[0099] Setting of thermal cycle test conditions:

[0100] Low temperature section: -55°C, keep warm for 30 minutes;

[0101] High temperature section: 125°C, keep warm for 30 minutes;

[0102] Heating / cooling rate: 15°C / min;

[0103] One cycle period: about 2 hours;

[0104] Testing equipment: ESPEC TSE-11-A type thermal cycle test chamber;

[0105] Sampling and detection frequency: Take out the samples for detection after every 100 cycles.

[0106] Detection method:

[0107] Use ultrasonic C-scan to detect the interfacial peeling situation;

[0108] Use a metallurgical microscope to observe the interfacial microstructure;

[0109] Calculation of interfacial peeling ratio: peeling area / total interfacial area × 100%.

[0110] 3. Test results:

[0111] See Figure 1 The results of the thermal cycle stability test.

[0112] 4. Result analysis: From the results of the thermal cycle stability test, it can be seen that after 500 thermal cycles, the interfacial delamination ratio of the composite material prepared by this method is only 3.2%, while the sample prepared by the traditional method reaches a delamination ratio of 11.5% after 200 thermal cycles and as high as 62.8% at 500 cycles. This result fully verifies that the triple protection mechanism of "thermal expansion coefficient gradient transition + phase change energy absorption + structural buffering" provided by this method can effectively reduce the interfacial stress during thermal cycling and significantly improve the thermal cycle stability of the material.

[0113] II. Thermal shock resistance test

[0114] 1. Experimental purpose: To evaluate the thermal shock resistance of the composite material prepared by this method in a rapid temperature change environment.

[0115] 2. Experimental steps:

[0116] Sample preparation: Prepare samples of silicon-aluminum-magnesium composite electronic packaging materials with dimensions of 30 mm × 30 mm × 3 mm according to the process of Embodiment 1. At the same time, prepare samples by the traditional method (without nano-porous structure and phase change material) as a control group.

[0117] Setting of thermal shock test conditions:

[0118] Low temperature end: -65°C;

[0119] High temperature end: 175°C;

[0120] Test different temperature change rates: 10°C / min, 30°C / min, 50°C / min, 70°C / min, 90°C / min;

[0121] Repeat the test 10 times at each temperature change rate;

[0122] Test equipment: A self-designed rapid temperature change test device composed of a liquid nitrogen cooling system and a resistance heating system;

[0123] Test method:

[0124] The sample is rapidly cooled from room temperature to -65°C and held for 10 minutes;

[0125] It is heated to 175°C at the set temperature change rate and held for 10 minutes;

[0126] It is cooled to -65°C at the same temperature change rate to complete one cycle;

[0127] After 10 cycles, acoustic emission technology and micro-CT were used to detect internal defects of the samples;

[0128] Defect density calculation: number of defects / sample volume (pieces / cm 3 ).

[0129] 3. Test results: see Figure 2 Thermal shock resistance test results.

[0130] 4. Result analysis:

[0131] The results of thermal shock resistance test show that when the temperature change rate reaches 50℃ / min, the internal defect density of the sample prepared by this method is 1.3 / cm 3 , while the internal defect density of samples prepared by traditional methods is as high as 8.4 / cm 3 When the temperature change rate was further increased to 70°C / min, the samples prepared by the traditional method had obvious cracks and interface peeling, and were judged to be failed. However, the samples prepared by this method could still maintain structural integrity, and the defect density was only 2.8 / cm 3 This proves that the synergistic effect of the nanoporous structure and the phase change energy absorbing material in this method greatly improves the material's resistance to thermal shock, enabling it to maintain structural integrity and stable performance under more extreme temperature change conditions.

[0132] 3. Long life characteristics test

[0133] 1. Experimental purpose: To verify the effect of the phase change material regeneration and activation treatment in this method on extending the service life of the material.

[0134] 2. Experimental steps:

[0135] Sample preparation: A silicon aluminum-magnesium composite electronic packaging material sample with a size of 40 mm×40 mm×4 mm was prepared according to the process of Embodiment 1. A control group sample without Se and Te elements and Y2O3 oxide particles was also prepared.

[0136] Testing process:

[0137] The samples were subjected to thermal cycle tests from 0-55°C to 125°C, and some samples were taken out for testing every 500 cycles;

[0138] After 2000 cycles, the remaining samples were subjected to phase change material activation treatment:

[0139] In 95%Ar+5%H2 atmosphere;

[0140] The temperature is 375°C;

[0141] Keep warm for 30 minutes;

[0142] After the activation treatment, the thermal cycle test is continued, and part of the samples are taken out for testing every 500 cycles;

[0143] The total number of cycles reaches 4000;

[0144] Test equipment: ESPEC TSE-11-A type thermal cycle test chamber, self-made atmosphere heat treatment furnace;

[0145] Testing method:

[0146] Differential scanning calorimetry (DSC) is used to test the endothermic enthalpy change of the phase change material, and the phase change ability retention rate is calculated: current enthalpy change value / initial enthalpy change value × 100%;

[0147] Ultrasonic C-scan is used to detect the interface peeling situation;

[0148] Three-point bending test is used to measure the interface bonding strength.

[0149] 3. Test results: See Figure 3 The test results of long-life characteristics.

[0150] 4. Result analysis:

[0151] The test results of long-life characteristics clearly show the effectiveness of the reactivation treatment of the phase change material in this method. When the thermal cycle reaches 2000 times, the phase change ability retention rate of the samples prepared by this method is 71.5%, close to the critical value of the activation treatment. After one activation treatment, the phase change ability retention rate is restored to 92.8%, almost returning to the performance level of the initial state. After 2000 cycles, the phase change ability retention rate of the control group samples is only 48.7%, and it cannot be restored by the activation treatment.

[0152] More significantly, after the samples of this method are subjected to another 2000 thermal cycles (a total of 4000 times) after the activation treatment, the phase change ability retention rate is still 70.4%, and the interface bonding strength is 76.8 MPa, still meeting the use requirements. After 4000 thermal cycles, the phase change ability retention rate of the control group samples has dropped to 25.3%, and the interface bonding strength is only 34.5 MPa, which can no longer meet the application requirements.

[0153] This result proves that the cycle regeneration system formed by Se and Te elements and Y2O3 oxide particles in this method can indeed realize the reactivation of the phase change material, significantly extend the service life of the material, and provide an effective solution for the long-term reliable use of electronic packaging materials.

[0154] IV. Interface Bonding Strength Test

[0155] 1. Experimental purpose: To evaluate the interface bonding strength of the composite material prepared by this method and its performance at different temperatures.

[0156] 2. Experimental procedures:

[0157] Sample preparation:

[0158] Experimental group: Samples of silicon-aluminum-magnesium composite electronic packaging materials were prepared according to the complete process of Embodiment 1;

[0159] Control group 1: Samples with no nano-porous structure and only a single-layer buffer layer;

[0160] Control group 2: Samples with no nano-porous structure, no buffer layer, and directly hot-pressed and compounded;

[0161] Sample size: Long strip specimens of 100mm×10mm×5mm;

[0162] Testing method:

[0163] The three-point bending test method (in accordance with ASTM D790 standard) was adopted;

[0164] Support point spacing: 80mm;

[0165] Loading rate: 2mm / min;

[0166] Testing temperature: -55°C, 25°C, 125°C, 175°C;

[0167] Testing equipment:

[0168] Instron 5567 universal material testing machine;

[0169] Equipped with a temperature control environmental chamber;

[0170] Testing procedure:

[0171] The samples were equilibrated at the testing temperature for 30 minutes;

[0172] The three-point bending test was carried out until the samples failed;

[0173] The maximum bending force and the failure mode were recorded;

[0174] The interfacial tensile strength was calculated.

[0175] 3. Test results:

[0176] See Figure 4 Test results of interfacial bonding strength.

[0177] See Figure 5 Analysis results of interfacial fracture morphology.

[0178] 4. Result analysis:

[0179] The results of the interfacial bonding strength test show that the interfacial tensile strength of the experimental group samples prepared by this method reaches 87.5 MPa at room temperature (25 °C), significantly higher than that of control group 1 (61.2 MPa) and control group 2 (38.6 MPa). More importantly, under extremely low temperature (-55 °C) and high temperature (175 °C) conditions, the experimental group samples still maintain relatively high interfacial tensile strengths, which are 92.3 MPa and 79.8 MPa respectively.

[0180] The analysis of the fracture morphology further confirms that the nano-porous structure of the experimental group samples and the double-layer buffer layer design form a good mechanical interlocking effect and gradient transition, and the interfacial bonding area ratio is as high as 85 - 92%. Even at a high temperature of 175 °C, the interfacial tensile strength still remains at a level of nearly 80 MPa, meeting the usage requirements of electronic packaging materials in harsh environments such as aerospace.

[0181] These results indicate that the gradient composition design of the multi-layer buffer structure and the application of the nano-porous structure in this method effectively solve the problem of the mismatch in thermal expansion coefficients between the silicon-aluminum alloy and the magnesium material, and significantly improve the interfacial bonding strength and temperature adaptation range.

[0182] V. Process Practicality Evaluation

[0183] 1. Experimental purpose: To evaluate the process stability, repeatability, cost-effectiveness and compatibility with existing production equipment of this method.

[0184] 2. Experimental steps:

[0185] Process repeatability test:

[0186] Continuously prepare 10 batches of samples under the same conditions;

[0187] The number of samples in each batch: 5 pieces;

[0188] Test the key performance indicators of each batch of samples and evaluate the data dispersion;

[0189] Equipment compatibility test:

[0190] Conduct process verification on laboratory small-scale equipment and industrial medium-scale equipment respectively;

[0191] Record the process parameter adjustment situation and product consistency;

[0192] Cost analysis:

[0193] Statistical analysis of raw material costs;

[0194] Measurement of process energy consumption;

[0195] Estimation of equipment depreciation;

[0196] Comprehensive cost comparison with traditional preparation methods;

[0197] Process robustness test:

[0198] Evaluate the impact of fluctuations in the main process parameters (temperature, pressure, time, etc.) within the allowable range on product performance.

[0199] 3. Test results:

[0200] See Figure 6 Process repeatability test results.

[0201] See Figure 7 Equipment compatibility test results.

[0202] See Figure 8 Cost analysis results.

[0203] See Figure 9 Process robustness test results.

[0204] 4. Results analysis:

[0205] The results of the process practicability evaluation show that this method has good process reliability and industrial application prospects:

[0206] High process repeatability: The coefficient of variation of the key performance indicators of 10 batches of samples is less than 3%, indicating that the process is stable and reliable and suitable for large-scale production.

[0207] Good equipment compatibility: This method can be implemented on equipment of different scales, from small laboratory equipment to large industrial equipment. The adjustment range of process parameters is small, and good product consistency is maintained.

[0208] Significant cost-benefit: Although the raw material cost has increased slightly (+14.3%), due to factors such as process simplification, increased yield, and significantly reduced maintenance cost, the comprehensive cost is reduced by 15.7% compared with the traditional method. In particular, the maintenance cost is reduced by 55.6%, which is mainly due to the on-site activation treatment of materials, reducing the replacement frequency.

[0209] Strong process robustness: Within the allowable fluctuation range of each process parameter, the impact on the key performance of the product is controlled within ±5%, indicating that the process has strong fault tolerance and adaptability.

[0210] These results fully verify the process practicability of this method, proving that this method can not only be realized under laboratory conditions but also stably produced under industrial conditions, and has obvious cost and performance advantages, suitable for popularization and application.

[0211] VI. Summary of experimental verification

[0212] Through the above series of experimental tests and evaluations, the forming method of the silicon-aluminum composite electronic packaging material proposed in this embodiment has achieved satisfactory results in multiple key indicators (see Figure 10 ).

[0213] These experimental verification results fully prove the technological innovation points and advantages of this embodiment:

[0214] The triple protection structure of "thermal expansion coefficient gradient transition + phase change energy absorption + structural buffer" can effectively solve the problem of mismatched thermal expansion coefficients between silicon-aluminum alloy and magnesium materials, and greatly improve the thermal cycle stability and thermal shock resistance of the material.

[0215] The synergistic mechanism between the nanoporous structure and the phase change energy absorption material has been verified. Experimental tests prove that this design can provide effective stress buffering and energy absorption in extreme temperature change environments.

[0216] The method for reactivating phase change materials is an important breakthrough in this embodiment. Experiments prove that after 2000 thermal cycles, the initial performance of more than 90% of the phase change materials can be restored through 30 minutes of activation heat treatment, significantly extending the service life of the materials.

[0217] The gradient composition design of the multi-layer buffer structure not only provides a gradual transition of the thermal expansion coefficient, but also enhances the interfacial bonding strength through the mechanical interlocking effect, enabling it to maintain good mechanical properties in a wide temperature range from -55°C to 175°C.

[0218] The process practicality evaluation shows that this method has good process stability, repeatability, and cost-effectiveness, can be realized on existing equipment, and is suitable for industrial promotion and application.

[0219] In summary, the forming method of the silicon-aluminum composite electronic packaging material proposed in this embodiment, through systematic experimental verification, proves its technical feasibility and practical value, and can provide strong support for the long-term reliable use of electronic devices in harsh environments in the fields of aviation, aerospace, military, etc.

[0220] The above describes the embodiments of the present invention. However, these embodiments are not limited to the above specific implementation manners. The above specific implementation manners are only illustrative, not restrictive. Under the inspiration of this embodiment, those of ordinary skill in the art can also make more equivalent embodiments in various forms, all of which fall within the protection scope of this embodiment.

Claims

1. A forming method for a gradient magnesium-silicon-aluminum composite electronic packaging material, characterized in that, It includes the following steps: Step 1: Treat the surface of the magnesium material, and spray a nano-porous Al-Cu-Mg alloy layer containing Se and Te elements on the surface of the magnesium material; Step 2: Prepare a first buffer layer on the nano-porous Al-Cu-Mg alloy layer, and the first buffer layer contains a Zn-Al eutectic phase material; Step 3: Prepare a second buffer layer on the first buffer layer, and the second buffer layer contains a Zn-Al-Mg ternary eutectic phase; Step 4: Thermally press and composite the magnesium material and its multi-layer buffer structure with a silicon-aluminum alloy sheet; Step 5: After the composite formed material serves for a certain period of time, perform activation heat treatment on the material in an atmosphere of 95% Ar + 5% H2 to restore the performance of the phase change material.

2. The method according to claim 1, characterized in that, Step 1 includes: Clean and pre-treat the surface of the magnesium material to remove the oxide layer and contaminants on the surface; Adopt the plasma spraying process to spray an Al-Cu-Mg alloy layer on the treated magnesium material surface, where the Al content is 70 - 75wt%, the Cu content is 20 - 25wt%, and the Mg content is 3 - 5wt%; Place the workpiece under argon protection, keep it warm at a temperature of 350 - 380°C for 1 - 2 hours, and then cool it to room temperature at a rate of 50 - 60°C per minute to form a nano-porous structure with a porosity of 15 - 25%; When preparing the Al-Cu-Mg alloy powder, add 1.5 - 2.5wt% of Se and Te elements, and disperse and add 0.3 - 0.8wt% of Y2O3 oxide particles.

3. The method according to claim 1, characterized in that, Step 2 includes: Prepare an Al-Mg alloy powder, where the Mg content is 35wt% and the Al content is 65wt%; Add 3 - 5wt% of Zn-Al eutectic phase material to the Al-Mg alloy powder; Adopt high-frequency induction melting of the Al-Mg alloy, and coat the alloy melt on the surface of the treated magnesium material at a temperature of 380 - 420°C, and control the thickness of the first buffer layer to be 0.5 - 0.8mm; Cool down at a cooling rate of 15 - 25°C / min to solidify the alloy and form a bond with the substrate.

4. The method according to claim 1, characterized in that, Step 3 includes: Prepare an Al-Mg-Si ternary alloy powder, where the Mg content is 18wt%, the Si content is 12wt%, and the Al content is 70wt%; Add 2 - 4wt% of Zn-Al-Mg ternary eutectic phase to the Al-Mg-Si alloy; Adopt the high-frequency induction melting process to coat the Al-Mg-Si alloy melt on the surface of the first buffer layer, control the thickness of the second buffer layer to be 0.5 - 0.8mm, and the coating temperature to be 400 - 450°C; Cool down at a cooling rate of 10 - 20°C / min to solidify the second buffer layer and form a bond with the first buffer layer.

5. The method according to claim 1, characterized in that, Step 4 includes: Assemble the prepared magnesium material and its multi-layer buffer structure with a silicon-aluminum alloy sheet to form a layered structure to be composite, and the composition of the silicon-aluminum alloy is Al - 50% Si; Place the assembled layered structure in a hot pressing device for hot pressing and composite, the hot pressing temperature is 450 - 520°C, and the pressure is 120 - 180MPa; After hot pressing reaches the set temperature and pressure, hold for 10 - 20 minutes, and then cool at a rate of 10 - 20 °C / min.

6. The method according to claim 1, wherein Step 5 includes: When the electronic packaging material undergoes about 2000 thermal cycles, the activation timing is determined by testing the endothermic enthalpy change of the phase change material by differential scanning calorimetry. When the enthalpy change value drops below 70% of the initial value, activation is carried out. In an atmosphere of 95% Ar + 5% H2, the material is heat-treated at 350 - 400 °C for 30 minutes.

7. The method according to claim 1, characterized in that, The phase change temperature of the Zn - Al eutectic phase in the first buffer layer is 275 - 285 °C, and the phase change temperature of the Zn - Al - Mg ternary eutectic phase in the second buffer layer is 340 - 350 °C, forming a gradient phase change temperature distribution.

8. The method according to claim 1, wherein The thermal expansion coefficient of the first buffer layer is 20×10 -6 / K, and the thermal expansion coefficient of the second buffer layer is 16×10 -6 / K, forming a gradual transition of the thermal expansion coefficient from the magnesium material to the silicon-aluminum alloy.

9. The method according to claim 2, wherein The Se and Te elements react with Y2O3 oxide particles at a temperature of 350 - 400 °C, form volatile suboxides under the reduction of hydrogen, and redeposit in the eutectic phase region to repair tissue coarsening and composition segregation.

10. The method according to claim 1, characterized in that, Through the surface treatment of the magnesium material, the preparation of the first buffer layer and the preparation of the second buffer layer, a triple protection structure of "thermal expansion coefficient gradient transition + phase change energy absorption + structural buffer" is formed.

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