Sintered silver is smelted into a record

Noble flower Sintered Silver: A Breakthrough from Laboratory Innovation to Industrial Innovation

In the evolution of electronic packaging materials, every material innovation has been accompanied by the reshaping of the industrial pattern. The sintered silver series products developed by Noble flower New Materials are rewriting the supply chain choices of 319 global leading companies with their disruptive performance - from power modules of new energy vehicles to superconducting chips for quantum computing, this connection material made of low-temperature sintering of nano-silver particles is at a high temperature limit of 961°C, 260W/m・K's ultra-high thermal conductivity, redefining the reliability standards of electronic devices. Exploring the refining trajectory of Noble flower sintered silver can not only see the breakthrough path of materials science, but also touch the innovative pulse of China's high-end electronic materials to achieve import substitution.

1. Industry pain points: the performance ceiling of traditional packaging materials

When the power density of silicon carbide chips exceeds 300W/cm² and the operating temperature of the RF module of 5G base stations climbs to 150°C, the performance shortcomings of traditional packaging materials become more and more prominent. In a 2015 market survey, the R&D team of Noble flower New Materials found that the field of electronic packaging is facing three irreconcilable contradictions:

The paradox between heat dissipation efficiency and temperature tolerance is particularly prominent in power devices. Conventional tin-based solder has a thermal conductivity of only 30-60W/m·K, which cannot export the heat generated by high-power chips in time, resulting in a 1°C increase in junction temperature that can shorten the device life by 10%. Test data from a new energy vehicle company shows that the chip temperature of the motor controller using SAC305 solder will rise by 20°C every 15 minutes when running at high load, and eventually fail due to thermal runaway. Although high-temperature brazing can withstand temperatures above 400°C, the process temperature of 600°C will cause irreversible damage to precision chips.

The contradiction between process temperature and material compatibility constrains sensitive device packaging. In products such as lidar and MEMS sensors, silicon-based and gallium nitride materials are extremely sensitive to temperature, and welding processes above 200°C may lead to component performance drift. Experiments by an optical module manufacturer have confirmed that traditional high-temperature soldering will reduce the coupling efficiency of silicon optical chips by 15%, which directly affects the transmission performance of 400G optical modules.

The imbalance between connection strength and reliability plagues complex applications. Automotive electronics During a temperature cycle of -40°C to 125°C, the shear strength of conventional solder can plummet from 30MPa to less than 5MPa, causing frequent joint failure in vibrating environments. Statistics show that the failure rate of in-vehicle electronic systems using traditional materials is as high as 8% per 100,000 kilometers, which is far from meeting the safety requirements of intelligent driving.

Behind these industry pain points are the inherent limitations of traditional materials at the atomic level - the low melting point characteristics of tin-based solder, the polymer insulating phase of conductive adhesives, and the risk of thermal damage from high-temperature brazing, which together constitute the performance ceiling of electronic packaging technology. The doctoral team of Noble flower New Materials realized that in order to break through this bottleneck, it is necessary to start from the essence of the material and find new connection materials with high thermal conductivity, high temperature resistance and low temperature process characteristics.

2. Technological breakthroughs: size effect and process innovation of nano-silver particles

The core breakthrough of Noble flower sintered silver lies in taming the "surface energy" characteristics of silver nanoparticles, transforming this nanomaterial, which is easily aggregated in nature, into an industrial-grade packaging material with stable performance. This process involves multi-dimensional innovation in material preparation, process development, and formulation optimization.

(1) Synergistic effect of mixed-size nano-silver

In the laboratory of Noble flower New Materials, the nano-silver particles under transmission electron microscopy show a carefully designed size distribution - large particles of 80nm and small particles of 20nm form a "gradient structure" in a ratio of 1:9. This innovative design stems from the team's deep understanding of sintering mechanisms:

Low-temperature activity of small-sized particles: 20nm silver particles account for up to 20% of surface atoms, and significant surface diffusion can occur at 150°C, powering low-temperature sintering;

Skeletal support for large-sized particles: 80nm particles form a rigid network to avoid volume shrinkage caused by excessive sintering of small particles (precise control from 60μm to 40μm);

Increased density due to gradation effect: Gap filling of two size particles results in density over 99%, which is 15% higher than that of single-size particles.

To solve the problem of silver nano-agglomeration, the team developed a "molecular-level coating" technology that forms a 3.3nm thick organic protective layer on the surface of silver particles, extending the stability period of the silver paste at 4°C to 6 months through steric hindrance. This protective layer will gradually decompose at 150°C, which will not hinder the sintering process and avoid the influence of residual carbon on the conductivity, and finally control the volume resistivity of the sintered layer below 5×10⁻⁸Ω・m.

(2) Paradigm revolution of low-temperature and pressure-free technology

The 150°C pressureless sintering process of Noble flower AG-100 has revolutionized the industry's perception of silver sintering. While traditional processes require high temperatures above 250°C and 10MPa pressure, the AG-100 can be sintered with a normal oven alone.

Surface energy-driven self-densification mechanism: The high surface energy of the nano-silver particles allows them to generate spontaneous diffusion dynamics at 150°C, forming a continuous conductive network through three-stage evolution of "neck growth-pore filling-grain boundary fusion". High-resolution electron microscopy showed that after 30 minutes of sintering, a sintered neck with a diameter of 10 nm was formed between the particles, and after 60 minutes, a connection layer with a density of more than 95% was formed.

A 100-fold jump in production efficiency: From a capacity of 30 pieces per hour with traditional silver sintering technology to a breakthrough of 3,000 pieces per hour with the AG-100, this is not only due to process simplification, but also due to the development of automated coating systems. The squeegee printing equipment independently designed by Noble flower New Materials can control the thickness of silver paste to 50±2μm and the line width accuracy of ±5μm, providing a stable process foundation for large-scale mass production.

According to the production line data of an optical module manufacturer, after using the AG-100 pressureless sintering process, the product yield has increased from 78% to 99.5%, the annual production capacity of a single production line has been expanded from 100,000 to 1 million pieces, and the unit manufacturing cost has been reduced by 40%.

(3) Scenario-based adaptation of formula design

Noble flower New Materials has built a product matrix covering different application scenarios, and each formula has been optimized through hundreds of orthogonal experiments:

AS9376's ultra-high thermal conductivity formulation: through the directional arrangement of 85% flake silver powder (diameter-to-thickness ratio 20:1), the high-efficiency thermal conductivity path is constructed, and the thermal conductivity of 260W/m・K is close to that of copper metal, which is especially suitable for high-power chips above 300W;

AS9335's low-temperature co-firing system: 10% modified epoxy resin is added to reduce the sintering temperature to 150°C while maintaining a shear strength of 25MPa, which is perfectly compatible with silicon-based and gallium nitride materials;

AS9385's pressurized sintering formulation: Active silver paste developed for bare copper substrates can form an Ag-Cu interdiffusion layer at 25MPa pressure, with a contact resistance as low as 5×10⁻⁵Ω·cm², breaking the dependence on precious metal coatings.

This scenario-based design has continuously expanded the application boundaries of Noble flower sintered silver - from a liquid helium environment (quantum chip) at -269°C to an automotive engine compartment at 200°C, from micron-sized sensor packaging to a large substrate of 100mm², showing strong environmental adaptability.

3. Product matrix: from laboratory samples to industrial-grade solutions

Noble flower New Materials has built a complete sintered silver product system in eight years, and each series corresponds to clear market demand, forming an accurate match between technical characteristics and application scenarios.

(1) Unpressurized semi-sintered silver: a cost-effective choice for large-area packaging

The AS9330 series works synergistically with resin and silver powder to provide reliable connections at 150-200°C pressure-free conditions. An application case of a photovoltaic inverter manufacturer shows that after using AS9335 to package 100mm×150mm IGBT substrates:

35% higher heat dissipation efficiency, increasing inverter conversion efficiency from 96.5% to 97.5%;

100°C reduction in process temperature avoids thermal distortion of the substrate (from 50μm to 5μm);

The material cost is reduced by 30% compared with imported products, and the annual procurement cost is saved by 12 million yuan.

This series is especially suitable for low- and medium-power scenarios such as optical communication modules and consumer electronics, and currently occupies 40% of the domestic pressureless sintered silver market.

(2) Unpressured fully sintered silver: a benchmark for reliability in the field of high performance

The AS9375 series relies entirely on the diffusion of silver particles to form connections, and although the process temperature is slightly higher (200-250°C), the performance indicators are better:

The volumetric resistivity < 5×10⁻⁸Ω·m, which is close to the conductivity level of bulk silver.

Shear strength exceeds 30MPa, and retention rate reaches 90% after 1000 temperature cycles (-55°C to 150°C);

The temperature resistance is up to 961°C, which is more than 5 times that of conventional solder.

In the field of quantum computing, the superconducting quantum chip of the University of Science and Technology of China adopts AG-100, which increases the resistance stability at liquid helium temperature by 10 times, providing a guarantee for the long coherence time of qubits. Tests by a quantum technology company have confirmed that the material's electromagnetic shielding properties reduce quantum state

manipulation errors by 60%.

(3) Pressurized sintered silver: a connection solution for extreme environments

The AS9385 series further increases density with pressure assistance (10-30MPa), making it superior in extreme environments. In the lidar of new energy vehicles, this product shows three advantages:

The chip junction temperature is reduced by 10°C, which improves the ranging accuracy of LiDAR from ±5cm to ±2cm;

The failure probability after vibration test (20-2000Hz, 20g) was reduced from 10% to 0.1%;

50% longer life, matching the 15-year / 300,000-kilometer service life of the car.

At present, the series has entered the supply chain of many leading car companies, and shipments in the automotive field will increase by 300% year-on-year in 2023.

4. Quality control: quality link from atomic level to industrial level

Noble flower New Materials has established a quality control system covering the whole life cycle, which perfectly combines the microscopic characteristics of nanomaterials with the consistency requirements of the industrial level.

The "silver powder ID card" system is implemented in the raw material screening process - each batch of nano silver powder needs to pass:

Dynamic light scatterometer (DLS) particle size distribution detection (CV value<5%);

X-ray fluorescence spectroscopy (XRF) purity analysis (silver content ≥99.99%);

Topography observation by scanning electron microscopy (SEM) (sphericity > 0.9).

A batch of silver powder was judged to be unqualified and recycled due to a standard deviation of particle size distribution exceeding the standard by 3%, which made the raw material qualification rate stable at more than 99.5%.

The production process uses a "digital twin" monitoring system to control key process parameters in real time:

The grinding gap of the three-roller machine is controlled at 5±0.1μm to ensure that the silver paste is evenly dispersed.

The stirring speed is maintained at 1500±50rpm to avoid secondary agglomeration of particles;

The temperature field uniformity of the curing furnace is controlled at ±2°C, ensuring consistent performance from batch to batch.

This system reduces the batch-to-lot variance rate from 5% to less than 1%, providing stable quality assurance for large-scale mass production.

The "performance pyramid" test system is constructed in the finished product testing process:

Base layer: resistivity (four-probe method), thermal conductivity (laser flash method);

Intermediate layer: shear strength (push-pull test), density (metallographic analysis);

Top layer: temperature cycling (-55°C to 150°C, 1000 times), moist-heat aging (85°C/85% RH, 1000 hours).

Only products that pass all 28 tests leave the factory, an almost demanding testing standard that has resulted in a customer complaint rate of less than 0.1% for Noble flower sintered silver for three consecutive years.

5. Market breakthrough: from technical recognition to ecological co-construction

The market expansion path of Noble flower sintered silver shows the typical paradigm of China's high-end materials from the laboratory to industrialization - winning reputation with technical performance, driving popularization with application cases, and finally realizing import substitution.

The breakthrough in the domestic market began in the field of third-generation semiconductors. In 2018, a test by a silicon carbide device manufacturer showed that a  1200V SiC module using AG100 had a power cycle life of 100,000 cycles, which is five times that of traditional solutions. This result prompted the manufacturer to include Nophiel sintered silver in the list of main suppliers, which subsequently led to a demonstration effect in the industry. At present, 80% of domestic SiC module manufacturers have adopted Noble flower's new materials products, promoting the reliability of domestic silicon carbide devices to reach the international leading level.

The penetration of the international market relies on the combination of "technology benchmarking + cost advantage". In a comparative test of an internationally renowned car company, Nophiel sintered silver showed that the performance indicators were the same as similar products in Japan, but the price was 20% lower and the delivery cycle was shortened by 50%. This cost-effective advantage has allowed it to successfully enter the company's global supply chain, with products now exported to 12 countries, increasing its share of the global sintered silver market from 1% in 2018 to 15% in 2023.

More strategic is the construction of industrial ecology. Noble flower New Materials, the Chinese Academy of Sciences, Tsinghua University and other institutions jointly established the "Nano Connection Technology Joint Laboratory" to promote the formulation of sintered silver standards; Cooperate with equipment manufacturers to develop special sintering furnaces to control process temperature fluctuations at ±1°C; Provide customers with full-process technical support from material selection to process optimization, and this "material + process + service" model shortens the customer's introduction cycle from 6 months to 2 months.

6. Future prospects: from material innovation to scene reconstruction

Noble flower's R&D pipeline has been extended to more cutting-edge application fields, and the next generation of technological breakthroughs is brewing:

The path to cost optimization is clearly visible. Through the development of a silver-clad copper core-shell structure (silver layer thickness of 5nm), material costs are reduced by 40% while maintaining 80% conductivity; The application of continuous sintering processes has reduced energy consumption by 50% per unit, and these innovations will drive the widespread adoption of sintered silver in mass markets such as consumer electronics.

The boundaries of performance continue to expand. The thermal conductivity of graphene-enhanced sintered silver under development is expected to exceed 300W/m·K; Antioxidant formula with rare earth elements can increase corrosion resistance by 10 times, providing solutions for extreme environments such as marine engineering and aerospace.

Scenario innovation leads new applications. In the field of flexible electronics, the stretchable sintered silver developed by Nophiel New Materials maintains its conductive path under 100% strain. In the field of biomedicine, antibacterial sintered silver provides a new option for implantable electronic devices. For ultra-high frequency modules for 6G communication, the research and development of ultra-low loss formulas has achieved phased results.

Behind these innovations is Noble flower New Materials' practice of the concept of "materials change the world". From the first nano silver sample in the laboratory to the mass production capacity of 3,000 pieces per hour on the production line, the refining of Noble flower sintered silver is not only a breakthrough history in material technology, but also a microcosm of China's high-end electronic materials to achieve independent and controllable results. In the future, with the unlocking of more application scenarios, this innovative material originating from China is expected to write a more brilliant chapter in the field of global electronic packaging.