Preparation process of high-temperature-resistant dispersion type TLPS soldering lug

Abstract

The invention discloses a preparation technology of a high-temperature-resistant dispersion type TLPS soldering lug. The technology comprises the steps that firstly, raw materials are prepared and inspected; 2, dispersion treatment of the copper powder; step 3, preparing and inspecting mixed powder; step 4, forming and inspecting a soldering lug; step 5, sintering treatment and inspection; and step 6, post-treatment and inspection. The rigidity of the soldering lug is effectively reduced through dispersion treatment of the copper layer in the Sn-CuTLPS soldering lug, and the dispersed copper layer structure enables the soldering lug to better adapt to thermal stress change in a high-temperature environment, so that the high-temperature stability of the soldering lug is remarkably improved, and meanwhile, by improving the stress distribution of a welding spot, the welding quality of the soldering lug is improved. The welding spots can bear stress more uniformly in the repeated thermal cycle process, the welding spot failure caused by stress concentration is avoided, the thermal cycle life of the welding spots is remarkably prolonged, the durability of an electronic device is improved, and the fragmented microstructures enable the rigidity of the soldering lug to be reduced and the uniformity to be improved.

Description

Technical Field

[0001] This invention relates to the field of TLPS solder pad technology, specifically a high-temperature resistant dispersion-type TLPS solder pad preparation process. Background Technology

[0002] TLPS solder pads, also known as transient liquid phase sintered solder pads, are a new type of welding material. Through their characteristics of low-temperature melting and high-temperature service, they achieve highly reliable electronic packaging interconnects. The solder pads contain mixed powders of low-melting-point metals and high-melting-point metals. During welding, the low-melting-point components melt to form a liquid phase, which reacts with the high-melting-point particles to generate intermetallic compounds, ultimately forming a stable high-melting-point connection.

[0003] Existing TLPS solder pads have the following drawbacks: First, the traditional Sn / Cu / Sn "sandwich" structure solder pads are prone to stress concentration at the solder joints due to their high stiffness under high-temperature environments, posing a serious threat to the stability and long-term reliability of the welded joints. Second, in SiC power device applications, solder joints often need to withstand repeated thermal cycling. Traditional solder pads often cannot withstand such repeated thermal stress tests, and their stiffness characteristics and stress concentration problems greatly shorten the thermal cycle life of the solder joints, affecting the durability of the devices. Third, from the perspective of welding process, traditional solder pads are also prone to stress concentration at the weld joints due to their own structural inhomogeneity or excessive stiffness during the welding process. This undoubtedly increases the risk of welding failure and adversely affects production efficiency and product quality. Summary of the Invention

[0004] The purpose of this invention is to provide a high-temperature resistant dispersion-type TLPS solder pad preparation process to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a high-temperature resistant dispersion-type TLPS solder sheet preparation process, comprising: step one, raw material preparation and inspection; step two, copper powder dispersion treatment; step three, mixed powder preparation and inspection; step four, solder sheet forming and inspection; step five, sintering treatment and inspection; and step six, post-treatment and inspection.

[0006] In step one above, high-purity Sn and Cu powders are selected, dried, sieved, and then tested for purity and particle size.

[0007] In step two above, Cu powder is pulverized by airflow to form a fragmented microstructure, and the particle size distribution and morphology are examined.

[0008] In step three above, Sn and Cu powders are mixed in proportion, additives are added and then mixed again, and the composition and morphology are tested.

[0009] In step four above, a mold is prepared, mixed powder is filled and pressed into shape, and the appearance and dimensions are inspected.

[0010] In step five above, the pre-sintered blank is sintered at high temperature to form an intermetallic compound, and its appearance, phase composition and mechanical properties are inspected.

[0011] In step six above, the solder pads are cooled, cleaned, polished, inspected and packaged, and stored in a dry and ventilated environment.

[0012] As a further technical solution of the present invention, in step one, Sn powder and Cu powder with a purity higher than 99.9% are selected to ensure that there are no impurities and oxides, so as to ensure the uniformity and density of the solder sheet. The raw materials are pretreated, specifically, the Sn powder and Cu powder are placed in a drying oven and dried at 100-150°C for 2-4 hours to remove moisture. The dried powder is then sieved using a vibrating sieve to remove oversized or undersized particles to ensure uniform particle size distribution. Then, the pretreated Sn powder and Cu powder are subjected to chemical composition analysis to ensure that the purity meets the requirements. The particle size distribution of the powder is detected using a laser particle size analyzer to ensure that it meets the process requirements.

[0013] As a further technical solution of the present invention, in step two, an air jet mill is selected, using high-purity nitrogen as the medium, with a pressure of 0.8–1.2 MPa and a flow rate of 50–80 m³ / s. 3 The pressure was 0.9 MPa per hour, the nozzle pressure was 0.9 MPa, and the impact angle was 60° to ensure that the Cu was pulverized to a D50 of 2–5 μm. The temperature of the pulverizing chamber was controlled below 40°C. The pulverized Cu powder was confirmed to be multi-faceted with an aspect ratio ≥3 by scanning electron microscopy, and the specific surface area was determined to be ≥2.5 m² by the BET method. 2 / g.

[0014] As a further technical solution of the present invention, in step two, the surface of the broken Cu powder is modified to prevent oxidation or adsorption of impurities on the surface of the Cu powder from hindering atomic diffusion. The Cu powder is coated with silane coupling agent KH-550 and ultrasonically dispersed for 30 minutes to improve the Cu-Sn interface bonding. 0.1% benzotriazole vapor is introduced in a vacuum environment to form a passivation film on the surface of the Cu powder to inhibit oxidation.

[0015] As a further technical solution of the present invention, in step three, Sn powder and fragmented Cu powder are mixed in proportion and placed in a three-dimensional mixer at a speed of 45-50 rpm for 2 hours. The mixer is eccentrically rotated to avoid segregation, and flux and leveling agent are added at the same time.

[0016] As a further technical solution of the present invention, in step three, the flux is: 3wt% active rosin (RMA grade) and 40% hydrogenated rosin acid (HIPA), and the leveling agent is: 0.5wt% polydimethylsiloxane (PDMS) with a dynamic viscosity of 100 cSt.

[0017] As a further technical solution of the present invention, in step four, according to the shape and size requirements of the welding sheet, a corresponding mold is designed and manufactured. The mold should have good wear resistance and corrosion resistance to ensure the forming quality of the welding sheet. The mixed powder is filled into the mold and vibrated and pressed using a vibrating table or press to make the powder tightly arranged. The appearance of the formed welding sheet blank is inspected to ensure that there are no cracks or missing corner defects.

[0018] As a further technical solution of the present invention, in step five, the formed welding sheet blank is placed in a sintering furnace for pre-sintering. The sintering curve is: 200℃→300℃, heating rate 5℃ / min, holding time 30 minutes, H2 atmosphere, dew point ≤-40℃, reducing oxides, so that the powder particles initially form a connection and improve the overall strength of the welding sheet.

[0019] As a further technical solution of the present invention, in step five, the TLPS reaction is as follows: Stage 1: 300℃→450℃ (10℃ / min), Sn liquid phase is formed; Stage 2: 450℃ isothermal for 1 hour, Cu6Sn5 (η phase) is generated; Stage 3: 600℃ / 10MPa hot pressing, holding for 30~60min, and the density is detected to be ≥98%.

[0020] As a further technical solution of the present invention, in step six, the sintered solder sheet is taken out from the sintering furnace and placed on a cooling platform for natural cooling. During the cooling process, the solder sheet is protected from rapid temperature changes to prevent cracking. The surface of the solder sheet is cleaned to remove residual flux and oxide impurities. Then, the surface of the solder sheet is polished to improve surface smoothness and welding performance. The processed solder sheet is subjected to final inspection, including visual inspection, dimensional measurement and performance testing. The qualified solder sheet is packaged and placed in a dry and ventilated environment to avoid moisture and oxidation.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention effectively reduces the stiffness of the solder sheet by dispersing the copper layer in the Sn-CuTLPS solder sheet. This dispersed copper layer structure enables the solder sheet to better adapt to thermal stress changes in high-temperature environments, thereby significantly improving the high-temperature stability of the solder sheet. At the same time, by improving the stress distribution of the solder joint, the solder joint can bear stress more evenly during repeated thermal cycling, avoiding solder joint failure caused by stress concentration, significantly extending the thermal cycle life of the solder joint, and improving the durability of electronic devices. The fragmented microstructure reduces the stiffness of the solder sheet and improves its uniformity, allowing the solder sheet to better fuse with the weld joint during the welding process, reducing the risk of stress concentration at the solder joint, improving the stability and reliability of the weld joint, reducing the risk of welding failure, and providing strong guarantees for production efficiency and product quality. Attached Figure Description

[0022] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] Please see the appendix Figure 1 The present invention provides an embodiment of a high-temperature resistant dispersion-type TLPS solder sheet preparation process, comprising: Step 1, raw material preparation and inspection; Step 2, copper powder dispersion treatment; Step 3, mixed powder preparation and inspection; Step 4, solder sheet forming and inspection; Step 5, sintering treatment and inspection; Step 6, post-treatment and inspection.

[0025] In step one above, Sn powder and Cu powder with a purity higher than 99.9% are selected to ensure the absence of impurities and oxides, thereby guaranteeing the uniformity and density of the solder sheet. The raw materials are pretreated by placing Sn powder and Cu powder separately in a drying oven and drying them at 100-150℃ for 2-4 hours to remove moisture. The dried powder is then sieved using a vibrating sieve to remove oversized or undersized particles, ensuring uniform particle size distribution. The pretreated Sn powder and Cu powder are then subjected to chemical composition analysis to ensure that the purity meets the requirements. Finally, a laser particle size analyzer is used to detect the particle size distribution of the powder to ensure that it meets the process requirements.

[0026] In step two above, Cu powder is pulverized using air jet milling to form a fragmented microstructure. The particle size distribution and morphology are then examined. An air jet mill is selected, using high-purity nitrogen as the medium, with a pressure of 0.8–1.2 MPa and a flow rate of 50–80 m³ / h. 3 The pressure was 0.9 MPa per hour, the nozzle pressure was 0.9 MPa, and the impact angle was 60° to ensure that the Cu was pulverized to a D50 of 2–5 μm. The temperature of the pulverizing chamber was controlled below 40°C. The pulverized Cu powder was confirmed to be multi-faceted with an aspect ratio ≥3 by scanning electron microscopy, and the specific surface area was determined to be ≥2.5 m² by the BET method. 2 / g, the surface of the crushed Cu powder is modified to prevent oxidation or adsorption of impurities on the surface of Cu powder from hindering atomic diffusion. The Cu powder is coated with silane coupling agent KH-550 and ultrasonically dispersed for 30 minutes to improve the Cu-Sn interface bonding. 0.1% benzotriazole vapor is introduced in a vacuum environment to form a passivation film on the surface of Cu powder to inhibit oxidation.

[0027] In step three above, Sn powder and fragmented Cu powder are mixed in proportion and placed in a three-dimensional mixer at a speed of 45-50 rpm for 2 hours. The mixer is eccentrically rotated to avoid segregation. At the same time, flux and leveling agent are added. The flux consists of 3 wt% active rosin (RMA grade) and 40% hydrogenated rosin acid (HIPA). The leveling agent consists of 0.5 wt% polydimethylsiloxane (PDMS) with a dynamic viscosity of 100 cSt.

[0028] In step four above, according to the shape and size requirements of the welding sheet, the corresponding mold is designed and manufactured. The mold should have good wear resistance and corrosion resistance to ensure the forming quality of the welding sheet. The mixed powder is filled into the mold and vibrated and pressed using a vibrating table or press to make the powder tightly arranged. The appearance of the formed welding sheet blank is inspected to ensure that there are no cracks or missing corners.

[0029] In step five above, the formed weld sheet blank is placed in a sintering furnace for pre-sintering. The sintering curve is: 200℃→300℃, heating rate 5℃ / min, holding time 30 minutes, H2 atmosphere, dew point ≤-40℃, reducing oxides, so that the powder particles can initially form a connection and improve the overall strength of the weld sheet. TLPS reaction: stage 1: 300℃→450℃ (10℃ / min), Sn liquid phase is formed; stage 2: 450℃ isothermal for 1 hour, Cu6Sn5 (η phase) is generated; stage 3: 600℃ / 10MPa hot pressing, holding time 30~60min, and the density is tested to be ≥98%.

[0030] In step six above, the sintered weld sheet is removed from the sintering furnace and placed on a cooling platform for natural cooling. During the cooling process, the weld sheet is protected from rapid temperature changes to prevent cracking. The surface of the weld sheet is cleaned to remove residual flux and oxide impurities. Then, the surface of the weld sheet is polished to improve surface smoothness and welding performance. The treated weld sheet undergoes a final inspection, including visual inspection, dimensional measurement, and performance testing. Qualified weld sheets are packaged and placed in a dry, ventilated environment to avoid moisture and oxidation.

[0031] Based on the above, the advantages of this invention are as follows: By dispersing the copper layer in the Sn-CuTLPS solder pad, this invention effectively reduces the stiffness of the solder pad. This dispersed copper layer structure allows the solder pad to better adapt to thermal stress changes in high-temperature environments, thereby significantly improving the high-temperature stability of the solder pad. This is undoubtedly an important performance improvement for electronic devices that need to operate in high-temperature environments for extended periods. Furthermore, it improves the stress distribution of the solder joints, enabling them to bear stress more evenly during repeated thermal cycling, avoiding solder joint failure caused by stress concentration, significantly extending the thermal cycle life of the solder joints, and improving the durability of electronic devices. By designing a fragmented microstructure, this invention significantly alleviates the overall stiffness of TLPS solder pads. This microstructure allows the solder pads to better fuse with the weld joint during the welding process, reducing the risk of stress concentration at the solder joint. This not only improves the stability and reliability of the weld joint but also reduces the risk of welding failure, providing strong assurance for production efficiency and product quality. In summary, this invention, through an innovative dispersion-type TLPS solder pad preparation process, effectively solves the problems of high stiffness, stress concentration, and short thermal cycle life of traditional TLPS solder pads under high-temperature environments, providing high-performance and high-reliability welding materials for the field of electronic packaging interconnection.

[0032] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A high-temperature resistant dispersion-type TLPS solder pad preparation process, comprising: Step 1, raw material preparation and inspection; Step 2, copper powder dispersion treatment; Step 3, mixed powder preparation and inspection; Step 4, solder pad forming and inspection; Step 5, sintering treatment and inspection; Step 6, post-treatment and inspection; characterized in that: In step one above, high-purity Sn and Cu powders are selected, dried, sieved, and then tested for purity and particle size. In step two above, Cu powder is pulverized by airflow to form a fragmented microstructure, and the particle size distribution and morphology are examined. In step three above, Sn and Cu powders are mixed in proportion, additives are added and then mixed again, and the composition and morphology are tested. In step four above, a mold is prepared, mixed powder is filled and pressed into shape, and the appearance and dimensions are inspected. In step five above, the pre-sintered blank is sintered at high temperature to form an intermetallic compound, and its appearance, phase composition and mechanical properties are inspected. In step six above, the solder pads are cooled, cleaned, polished, inspected and packaged, and stored in a dry and ventilated environment.

2. The process for preparing a high-temperature resistant dispersion-type TLPS solder sheet according to claim 1, characterized in that: In step one, Sn powder and Cu powder with a purity higher than 99.9% are selected to ensure the absence of impurities and oxides, thereby guaranteeing the uniformity and density of the solder sheet. The raw materials are pretreated by placing Sn powder and Cu powder separately in a drying oven and drying them at 100-150°C for 2-4 hours to remove moisture. The dried powder is then sieved using a vibrating sieve to remove excessively large or small particles, ensuring uniform particle size distribution. The pretreated Sn powder and Cu powder are then subjected to chemical composition analysis to ensure that the purity meets the requirements. Finally, a laser particle size analyzer is used to detect the particle size distribution of the powder to ensure that it meets the process requirements.

3. The process for preparing a high-temperature resistant dispersion-type TLPS solder sheet according to claim 1, characterized in that: In step two, an air jet mill is selected, using high-purity nitrogen as the medium, with a pressure of 0.8–1.2 MPa and a flow rate of 50–80 m³ / s. 3 The pressure was 0.9 MPa per hour, the nozzle pressure was 0.9 MPa, and the impact angle was 60° to ensure that the Cu was pulverized to a D50 of 2–5 μm. The temperature of the pulverizing chamber was controlled below 40°C. The pulverized Cu powder was confirmed to be multi-faceted with an aspect ratio ≥3 by scanning electron microscopy, and the specific surface area was determined to be ≥2.5 m² by the BET method. 2 / g.

4. The process for preparing a high-temperature resistant dispersion-type TLPS solder sheet according to claim 3, characterized in that: In step two, the fragmented Cu powder is surface modified to prevent oxidation or adsorption of impurities on the Cu powder surface from hindering atomic diffusion. The Cu powder is coated with silane coupling agent KH-550 and ultrasonically dispersed for 30 minutes to improve the Cu-Sn interface bonding. 0.1% benzotriazole vapor is introduced under vacuum to form a passivation film on the Cu powder surface to inhibit oxidation.

5. The process for preparing a high-temperature resistant dispersion-type TLPS solder sheet according to claim 1, characterized in that: In step three, Sn powder and fragmented Cu powder are mixed in proportion and placed in a three-dimensional mixer at a speed of 45-50 rpm for 2 hours. The mixer is eccentrically rotated to avoid segregation. At the same time, flux and leveling agent are added.

6. The high-temperature resistant dispersion-type TLPS solder sheet preparation process according to claim 5, characterized in that: In step three, the flux consists of 3wt% activated rosin (RMA grade) and 40% hydrogenated rosin acid (HIPA), and the leveling agent consists of 0.5wt% polydimethylsiloxane (PDMS) with a dynamic viscosity of 100 cSt.

7. The process for preparing a high-temperature resistant dispersion-type TLPS solder sheet according to claim 1, characterized in that: In step four, according to the shape and size requirements of the welding sheet, a corresponding mold is designed and manufactured. The mold should have good wear resistance and corrosion resistance to ensure the forming quality of the welding sheet. The mixed powder is filled into the mold and vibrated and pressed using a vibrating table or press to make the powder tightly arranged. The formed welding sheet blank is visually inspected to ensure that there are no cracks or missing corners.

8. The process for preparing a high-temperature resistant dispersion-type TLPS solder sheet according to claim 1, characterized in that: In step five, the formed weld sheet blank is placed in a sintering furnace for pre-sintering. The sintering curve is: 200℃→300℃, heating rate 5℃ / min, holding time 30 minutes, H2 atmosphere, dew point ≤-40℃, reducing oxides, so that the powder particles can initially form a connection and improve the overall strength of the weld sheet.

9. The process for preparing a high-temperature resistant dispersion-type TLPS solder sheet according to claim 8, characterized in that: In step five, the TLPS reaction is as follows: Stage 1: 300℃→450℃ (10℃ / min), Sn liquid phase is formed; Stage 2: 450℃ isothermal for 1 hour, Cu6Sn5 (η phase) is generated; Stage 3: 600℃ / 10MPa hot pressing, holding for 30~60min, density is detected as ≥98%.

10. The process for preparing a high-temperature resistant dispersion-type TLPS solder sheet according to claim 1, characterized in that: In step six, the sintered weld sheets are removed from the sintering furnace and placed on a cooling platform for natural cooling. During the cooling process, the weld sheets are protected from rapid temperature changes to prevent cracking. The surface of the weld sheets is cleaned to remove residual flux and oxide impurities. Then, the surface of the weld sheets is polished to improve surface smoothness and welding performance. The treated weld sheets undergo final inspection, including visual inspection, dimensional measurement, and performance testing. Qualified weld sheets are packaged and placed in a dry, ventilated environment to prevent moisture and oxidation.

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