The accelerator of the silicon carbide power semiconductor revolution: the rise of domestic sintered silver

The packaging revolution of silicon carbide power semiconductors: the rise of domestic sintered silver technology

When a new energy vehicle completes a "cup of coffee time" next to an 800V high-voltage fast charging pile, when a photovoltaic inverter injects 12% of the additional power generation into the grid under the scorching sun, and when the RF module of a 5G base station maintains stable operation in extreme temperature differences - behind these scenarios, it is inseparable from the breakthrough of third-generation power semiconductors with silicon carbide as the core. What supports these high-performance chips to realize their ultimate potential is the sinteredsilver packaging technology from behind the scenes to the front of the stage. This innovative process of converting silver nanoparticles into "electronic joints" is redefining the reliability standards of power devices with a high temperature resistance limit of 961°C and an ultra-high thermal conductivity of 260W/m・K, and has become a key starting point for China to achieve corner overtaking in the field of high-end electronic materials.

1. Sintered silver technology: the art of atomic-level connection in the microscopic world

The magic of sintered silver technology lies in its qualitative change from "particle accumulation" to "atomic fusion", a microscopic level of precision manipulation that allows electronic connections to jump from "glue bonding" to a new height of "metal bonding".

The self-assembly mechanism of the nano-silver particles forms the core of the technology. In a temperature field of about 250°C, silver particles with a diameter of only 50-100nm seem to be given life, and "self-welding" is completed through surface diffusion and grain boundary migration. This process can be clearly observed under high-resolution electron microscopy: in the initial stage, adjacent particle contact points form a "sintered neck" with a diameter of about 10 nm; As the insulation time increases, the neck continues to thicken, eventually forming a continuous structure with a density of more than 95%. This connection is much stronger than conventional solder – the shear strength can be more than 30MPa, which is 3 times that of tin-based solders, and is strong enough to withstand the constant vibration and temperature shock of the automobile's engine compartment. The essential breakthrough of high-temperature resistance comes from the characteristics of the material itself. Unlike traditional solders, which typically have a melting point below 250°C, the melting point of the sintered silver structure is consistent with that of sterling silver, up to 961°C, meaning that the connecting layer maintains the stability of the solid metal even at the silicon carbide chip's operating temperature of 175°C. Extreme tests in an automotive electronics lab showed that after 1,000 hours of continuous operation at 300°C at 300°C, the resistance of power modules increased by only 5%, while conventional solder had long since softened and failed at this temperature. The generational difference with traditional solder is reflected in multiple dimensions. If traditional solder is compared to "building blocks bonded with glue", then sintered silver is a "poured alloy structure": Thermal cycling stability: In 1000 cycles of -65°C to 150°C, sintered silver has a resistance change rate of <10%, while tin-based solder will crack due to thermal fatigue, and the resistance will soar by more than 50%; Thermal conductivity: 260W/m・K The thermal conductivity is the same as that of SAC305 solder (60W/m・). K), which can quickly export the heat generated by the chip; Service life: Under new energy vehicle conditions, the life expectancy of sintered silver modules can reach 15 years/300,000 kilometers, which is 5 times that of traditional solutions. This performance jump just matches the application needs of silicon carbide power devices - when the chip power density is increased from 50W/cm² for silicon to 300W/cm² for silicon carbide, only sintered silver can solve the core problem of "reliable heat dissipation at high heat flux density".

2. The heat dissipation revolution of power devices: from "small stove" to "highway"

The high-efficiency performance of silicon carbide chips is inseparable from the "thermal management highway" built by sintered silver, which brings not only the reduction of temperature, but also the comprehensive upgrade of electric vehicle range, charging speed and space utilization. The significant reduction in chip temperature creates multiple values. In the motor controller of new energy vehicles, the silicon carbide module connected by sintered silver can reduce the chip junction temperature by more than 50°C. Real vehicle tests by a car company show that this temperature optimization brings three direct benefits: 12% increase in range: the same 60kWh battery pack extends the range from 500 to 560 km, which is due to the increase in module efficiency from 96% to 97.5%; Fast charging capability breakthrough: supports continuous high power output of 800V high-voltage platforms, reducing charging time from 40 minutes (30%-80%) to 20 minutes; Significantly reduced size: The cooling system is reduced by 1/4 of the size, freeing up more space for the battery compartment and indirectly improving battery life. Optimization of heat conduction paths is a key mechanism. The continuous metal network formed by sintered silver transfers the heat generated by the chip directly to the heat dissipation base, with a thermal resistance as low as 0.05°C/W, which is only 1/3 of that of conventional solder. In PV inverters, this efficient heat dissipation reduces the operating temperature of IGBT modules by 30°C and increases conversion efficiency by 0.5 percentage points – for a 1GW PV plant, this translates to 5 million kWh more electricity per year, equivalent to 3,000 tons of CO2 emissions saved. Increased power density drives device miniaturization. According to the test data of a charging pile company, the size of the 30kW module using sintered silver technology has been reduced from 4L to 2.5L in the traditional scheme, and the power density has been increased by 60%, which makes the installation of charging piles more flexible and the cost of a single pile is reduced by 20%. In 5G base stations, the miniaturization of RF modules means that more channels can be integrated in a limited space and signal coverage can be increased by 30%.

3. The ultimate guarantee of reliability: the technical confidence of ten years of warranty

When Tesla dared to promise a "10-year unlimited mileage warranty for motor controllers", when BYD's power module life increased by 5 times, behind these quality upgrades was the excellent performance of sintered silver technology in extreme environments, which changed the reliability of electronic devices from "probability guarantee" to "inevitable result". The extreme test of hot and cold cycling verifies the toughness of the material. In temperature cycling tests from -65°C to 150°C, the sintered silver junction shows a unique ability to "self-heal" – tiny cracks created with each cycle are partially repaired by the diffusion of silver atoms during subsequent high-temperature phases. After 1000 cycles, its shear strength remains above 80% of its initial value, while traditional solder has experienced significant delamination at this stage, losing more than 50% of its strength. According to a report from a third-party testing agency, the failure probability of silicon carbide modules using sintered silver is only 0.1% in the test simulating the whole life cycle of automobiles, which is far lower than the 5% of traditional solutions. Comprehensive protection for vibration and shock is suitable for complex working conditions. In vibration tests (20-2000Hz, 20g acceleration) in automotive electronics, the sintered silver connection layer also performed well. Through finite element analysis, it is found that its nanoscale polycrystalline structure can effectively absorb vibration energy, and the stress concentration coefficient is 40% lower than that of traditional solder. A field test by a commercial vehicle company showed that after driving 100,000 kilometers of bumpy road sections, the failure rate of the electronic control system using sintered silver was only 0.3%, compared with 3.5% of the traditional solution. Long-term resistance to humidity and corrosion expands the boundaries of application. After 1000 hours of humid and hot environment at 85°C/85% RH, the resistance change rate of the sintered silver layer <3%, which is due to its high density and low porosity (<1.2%), which effectively prevents the intrusion of water vapor and pollutants. In offshore wind inverters, this corrosion resistance extends equipment maintenance intervals from 1 to 3 years and reduces O&M costs by 60%.

Fourth, the breakthrough road of domestic substitution: from technology to global leadership

In the past, companies such as Alpha in the United States and Heraeus in Germany monopolized the global sintered silver market, and the price of materials was as high as tens of thousands of yuan per kilogram, which became a "bottleneck" link restricting the development of China's silicon carbide industry. Today, Chinese enterprises represented by Wuxi Dike Paitai have broken the monopoly through technological innovation, so that domestic sintered silver not only has a performance comparable to imports, but also forms unique advantages in cost and service.

The technological breakthrough of DECA610-02T silver paste is a milestone. This domestic silver paste has achieved three major innovations: low-temperature sintering characteristics: sintering can be completed at 230°C, which is 20°C lower than imported products, and is more suitable for substrate materials that are not resistant to high temperatures; Low porosity control: By optimizing the particle size distribution of silver powder (D50=1μm, Span=1.2) and organic carrier formulation, the porosity of the sintered layer was < to 1.2%, and the density reached 98%.

Batch Stability: Batch-to-batch resistance fluctuates < 3%, far exceeding the industry standard of 5%, meeting the stringent requirements of automotive electronics.

A comparative test by a silicon carbide module manufacturer showed that the product using DECA610-02T was on par with Heraeus products in Germany in various performance indicators, but the procurement cost was reduced by 30%, and the lead time was shortened from 12 weeks to 4 weeks. The industrialization of large-area sintering technology has promoted cost reduction. The "pressureless sintering process" developed by Dike Paitai successfully solves the uniformity problem of sintering large areas above 50mm × 50mm, and improves the sintering yield from 60% to 95%. This technological breakthrough directly reduces the cost of silicon carbide modules by 30% and accelerates its popularization in new energy vehicles - NIO ET7 became the first mass-produced model equipped with domestic sintered silver modules, with an electric drive system efficiency of 97.5% and support 4.5 seconds of acceleration to 100 kilometers per hour. Collaborative innovation in the industrial chain builds ecological advantages. Domestic enterprises are forming a complete industrial chain from silver powder preparation to sintering equipment: the performance of spherical silver powder (purity 99.99%, particle size 50nm) developed by an enterprise in Ningbo has reached the international advanced level; The pressure sintering equipment of a manufacturer in Shenzhen has a temperature control accuracy of ±1°C and a pressure uniformity of <2%. This independent and controllable whole chain has increased the number of patents in China in the field of sintered silver technology from less than 100 in 2018 to more than 500 in 2023, accounting for 40% of the world.

5. The future picture of cross-border applications: the material revolution from automobiles to space

The application boundaries of sintered silver technology are constantly expanding, which is not only the "best partner" for silicon carbide devices, but also creates new possibilities in photovoltaic, aerospace, energy storage and other fields, and promotes the technological upgrading of multiple industries. The efficiency leap of photovoltaic inverters reflects significant value. In the 1500V photovoltaic inverter, the IGBT module connected with sintered silver is used to increase the conversion efficiency by 0.3 percentage points, which means that a 100MW photovoltaic power plant can generate 600,000 kWh more electricity per year. What's more, its high-temperature reliability increases the upper operating temperature limit of the inverter from 70°C to 90°C, reducing the investment in the cooling system and reducing the cost per unit by 15%. Aerospace adaptation to extreme environments shows unique advantages. After using domestic sintered silver devices, the power controller of the Chinese space station has continued to operate stably for more than 3 years in the alternating high and low temperatures (-100°C to 120°C) and strong radiation environments in space, and there is no significant drift in various parameters. In the commercial satellite sector, this reliability extends the design life of satellites from 5 to 8 years and increases payload per unit weight by 20%. The safety upgrade of the energy storage system provides a new solution. In liquid-cooled energy storage converters, the high-temperature resistance of sintered silver modules reduces the risk of thermal runaway. Tests of an energy storage power station showed that the thermal diffusion time of the system using this technology was extended from 10 minutes to 30 minutes in the event of overcharging, short circuit, and other faults, buying valuable time for safety protection. At the same time, its long-life characteristics enable the energy storage system to exceed 15,000 cycles, which is close to the service life of the battery, reducing intermediate replacement costs.

Conclusion: The industrial leap behind the material revolution

The rise of sintered silver technology is not only a material substitution, but also an innovation in manufacturing concepts - it has changed the design of power devices from "accommodating material performance" to "unleashing chip potential", clearing obstacles for the large-scale application of third-generation semiconductors such as silicon carbide. As the performance and cost advantages of domestic sintered silver continue to be highlighted, China's competitiveness in the field of power semiconductors is undergoing qualitative changes: from relying on imported chips to achieving independent control of the whole chain from materials to devices. The impact of this change will be far-reaching: the endurance and safety of new energy vehicles will reach a new level, the cost of photovoltaic and energy storage will continue to decline, and the coverage and capacity of 5G communication will continue to increase. Just as lithium batteries have promoted the mobile Internet revolution, sintered silvertechnology is laying the "material cornerstone" for the development of new energy and intelligent manufacturing, and the leading position of Chinese companies in this material revolution will contribute unique oriental wisdom to the progress of the global electronics industry.