Industrialization and technological breakthroughs of tin-based new materials

 Industrialization exploration and technological innovation of tin-based new materials

With the rapid development of microelectronic packaging technology, tin-based new materials have become a key link connecting microscopic circuits and macroscopic devices with their unique physical and chemical properties. From ultra-fine solder wires with a diameter of only 0.1 mm to precision solder balls that support chip interconnection, these seemingly tiny materials carry the core demands of high performance and reliability in electronic devices. Through more than ten years of technical research, Nofil New Materials has achieved a number of breakthroughs in the field of precision manufacturing of tin-based materials, and its developed Sn-Ag-Cu alloy system products have been widely used in high-end fields such as aerospace, medical care, and 5G communications, redefining the application boundaries of tin-based materials in advanced manufacturing.

1. Ultra-fine solder wire: the limit breakthrough of micron-level manufacturing

Walking into the tin wire production workshop of Nophiel New Materials, a special scenery catches the eye: in a relatively enclosed clean space, a precision machine is "spitting" out wires thinner than a hair at a steady rate - this is the ultra-fine solder wire production line with a diameter of only 0.1 mm. Logos on glass windows clearly display product specifications, while flashing indicators on the production line bear witness to the transformation from raw metal to precision wire.

1. Precision forging in ten processes

The production of φ0.1mm ultra-fine solder wire can be called the "Everest" in the field of metal precision processing, which needs to be quenched layer by layer through ten processes such as solder alloy ratio, ingot casting, extrusion, rough drawing, medium drawing, fine drawing, ultra-fine drawing, annealing, cleaning, and quality inspection. Each process has strict parameter control, and any slight deviation can lead to the performance failure of the final product.

Taking the alloy ratio as an example, Nofil's Sn-Ag-Cu ternary system (tin-silver-copper ratio of 63:37) is not a simple mixing of components, but a uniform distribution at the atomic level through vacuum melting technology to ensure consistent melting characteristics of the materials during the welding process. In the ingot stage, gradient temperature-controlled extrusion technology is used to accurately control the temperature within the range of 825±5°C, effectively eliminating grain boundary defects within the metal through slow heating and directional solidification, laying a solid foundation for the subsequent drawing process.

2. Innovative breakthroughs in three core technologies

(1) Gradient temperature-controlled extrusion: the key to eliminating microscopic defects

While the traditional ingot process often causes defects such as porosity and segregation inside the metal due to uneven temperature distribution, the gradient temperature-controlled extrusion technology uses computer simulation and real-time temperature monitoring to make the metal melt form a stable temperature gradient in the mold and achieve uniform cooling from the center to the edge. This process not only increases the density of the ingots to more than 99.9%, but also significantly reduces the risk of fracture during subsequent drawing.

(2) Nanoscale lubrication pull-out: the art of controlling the amount of deformation

In the process of fine drawing and ultra-fine drawing, the material needs to undergo multiple plastic deformations, and the control of the deformation of the pass directly affects the mechanical properties and dimensional accuracy of the wire. The molybdenum disulfide composite lubricant developed by Nofil can form a nanoscale lubricating film on the metal surface, which not only reduces frictional resistance, but also provides real-time feedback on the stress distribution during the deformation process. By tightly controlling the deformation of the pass at 18-22% of the safe range, the final result is a precise control of 0.1 mm diameter with less than 3 μm of wire roundness.

(3) Online diameter monitoring: control the dimensional accuracy throughout the process

To ensure product consistency, the line is equipped with a laser diameter gauge with an accuracy of up to ±0.5μm, capable of performing more than 1000 diameter measurements per meter of wire. The measurement data is transmitted to the central control system in real time, and once the deviation exceeds the preset range, the system will automatically adjust the pulling speed and tension to achieve closed-loop control. This online monitoring technology improves the dimensional qualification rate of products to more than 99.9%.

3. Application verification in high-end fields

The test data shows that the ultra-fine Сварная проволока has a soldering yield of 99.7% in a 0.3mm pitch QFP (Quad Flat Package), which is much higher than the industry average of 95%. In the thermal fatigue performance test, after 5,000 cycles of testing according to JIS Z3198, the resistance change rate of the solder joint was still controlled within 5%, demonstrating excellent reliability.

At present, the product has passed the international certification of IPC-J-STD-004B and is widely used in three high-end fields:

Aerospace electronics: high-density interconnection of multi-layer PCB boards for satellites, maintaining stable electrical performance in vacuum, high and low temperature alternating environments;

Medical devices: As a connection material for implantable sensor micropackages, meeting the requirements of biocompatibility and long-term reliability;

5G communication: Applied to the assembly of millimeter-wave RF modules, supporting low-loss transmission of high-frequency signals.

2. BGA solder ball array: precision manufacturing of tiny particles

In the sample room of Nofil New Materials, a glass jar the size of a household flavoring bottle caught our attention. According to the staff, this seemingly ordinary container is actually loaded with about 5 million solder balls, and its heavy weight can be clearly felt in your hand. These "tiny solder balls", ranging in diameter from 0.3 mm to 1.0 mm, are the core components of BGA (Ball Grid Array) packaging technology.

1. Technological leap from pin to solder ball

Traditional chip packages use the pins of the lead frame for electrical connection, but as chip integration increases, the problem of "pin bottlenecks" caused by the proliferation of pin count is becoming more prominent. BGA packaging technology not only achieves a significant increase in the number of pins (from hundreds to thousands) by placing array solder balls on the bottom of the chip instead of traditional pins, but also significantly shortens the signal transmission path and reduces parasitic parameters.

However, the manufacturing of BGA solderballs is not an easy task. "Each solder ball needs to go through strict size control, roundness screening and oxidation protection, and there is not much mature experience to learn from in China, and our production process and equipment parameters are accumulated through thousands of experiments." The technical director of Nofil said.

2. Performance comparison between traditional and optimized processes

Through continuous technological innovation, Nophiel has achieved a number of breakthroughs in the field of BGA solder ball manufacturing, and the optimized process has made a qualitative leap in key indicators compared to traditional processes:

Among them, the composite antioxidant coating technology is Nofil's original process: by forming a nanoscale organic-inorganic composite film on the surface of the solder balls, it does not affect the melting characteristics during the soldering process, and the oxygen content can be controlled below 50ppm (ASTM E1447 standard), effectively solving the oxidation problem of solder balls during storage and transportation.

3. Technical advantages of centrifugal atomization milling system

The centrifugal atomization milling system independently developed by the company is the core equipment to achieve the above performance breakthrough, which breaks the molten tin alloy into tin droplets through a high-speed rotating atomization disc, and forms spherical particles after cooling. Its technical advantages are mainly reflected in three aspects:

Concentrated particle size distribution: D10/D90≤1.2 (indicating that the ratio of 90% particle diameter to 10% particle diameter does not exceed 1.2), which is much better than the industry average of 1.5, ensuring melt consistency during welding;

Excellent roundness of the sphere: optimize the atomization disc structure through fluid dynamics simulation, so that the roundness error of the sphere is less than 2%, and ensure that the contact area is uniform during welding;

Efficient and stable production capacity: 1.2 million φ0.3mm solder balls can be produced per hour, and the performance fluctuation between batches is less than 3%.

4. Application cases in the field of automotive electronics

After a leading automotive electronics company adopted Nofil's Sn96.5Ag3.0Cu0.5 alloy solder balls, the reflow defect rate of its BGA packaging products dropped from 850ppm (parts per million) to 120ppm, a decrease of 86%. This improvement not only significantly reduces production costs, but also significantly improves the reliability of automotive electronic control units (ECUs) in high-temperature and vibration environments, providing an important guarantee for the safe operation of autonomous driving systems.

3. Industry-university-research collaboration: build an innovation ecosystem

The technological breakthrough of tin-based new materials is not accidental, but stems from the "trinity" industry-university-research collaborative innovation system built by Nofil. The system organically combines basic research, application development and skill practice, forming a complete chain from laboratory results to industrial application.

1. Basic research layer: build a solid technical foundation

Nofil and the Institute of Metals of the Chinese Academy of Sciences jointly established the "Joint Laboratory of Tin-based Materials", focusing on cutting-edge topics such as the relationship between microstructure and performance of tin-based alloys and the composition design of new lead-free solders. The laboratory is equipped with high-end equipment such as transmission electron microscope (TEM) and X-ray diffractometer (XRD), which provides strong support for basic research.

The postdoctoral workstation set up by the company currently has 8 doctoral students, who are engaged in the preparation of nano tin powder and the reaction mechanism of solder interface. In the past three years, the workstation has published 32 SCI papers, providing theoretical guidance for technological innovation of enterprises.

2. Application development layer: Accelerate the transformation of results

At the application development level, Nofil implements a dual-track system of "project manager + technical expert": the project manager is responsible for market demand research and project progress management, while the technical expert focuses on process optimization and product performance improvement. This mechanism ensures the precise alignment between R&D direction and market demand.

Companies invest 4.2% of their revenue in R&D each year, which is 1.8 times the industry average. In 2023, the company applied for 56 patents (including 23 invention patents), led the formulation of 3 industry standards, and the conversion rate of scientific and technological achievements reached 82% (an increase of 11 percentage points over the previous year), significantly higher than the industry average of 60%.

3. Skill practice layer: cultivate professional talents

In order to cultivate high-level skilled talents, Nofil has established a national skill master studio, led by technical experts who enjoy special allowances from the State Council, and carries out the "mentor-apprentice" training program. The studio has also introduced the German SIEMENS certified ME (Manufacturing Engineering) training system, covering precision machining, quality control and other fields, and trains more than 200 skilled talents every year.

This multi-level talent training mechanism enables enterprises to have both top R&D teams and high-quality industrial workers, providing a double guarantee for technological innovation and industrial application.

4. Future prospects: technology trends and industrial layout

As the global electronics manufacturing industry develops in the direction of green and intelligent, new tin-based materials are facing new opportunities and challenges. Based on deep insight into industry trends, Nophil is laying out three strategic directions:

1. Compliant material development: Responding to new international regulations

The EU SCIP (Substances of Concern In articles as such or in complex objects) database has increasingly strict restrictions on tin-containing products, making lead-free solder an inevitable trend in the development of the industry. Nofil is developing a new lead-free solder system with a melting point of ≤ 195°C, which adjusts the melting characteristics of the alloy by adding trace rare earth elements, so that it can meet environmental protection requirements while maintaining soldering performance comparable to that of traditional tin-lead solders.

2. Expansion of emerging application fields

(1) Application of tin-based flame retardants in lithium battery packs

The safety of lithium batteries has always been the focus of the industry, and the tin-based flame retardant developed by Nofil can effectively inhibit battery thermal runaway by forming a molten cover and trapping free radicals. In the needle punching experiment, the lithium battery pack with the flame retardant did not show open flame and explosion, which provided a new solution for improving the safety performance of new energy vehicles.

(2) AI-driven process parameter optimization

Enterprises are building an AI-based process parameter optimization system to establish a prediction model by collecting massive data in the production process (such as temperature, pressure, speed, etc.) to achieve independent adjustment of process parameters. The pilot application of the system has resulted in a 3.2 percentage point increase in production yield and a 15% increase in production efficiency for ultra-fine solder wires.

3. Industrial upgrading direction: from micron to submicron

To meet the miniaturization needs of next-generation electronic devices, Nofil is working to advance the processing accuracy of tin-based materials from the micron level to the sub-micron level. Through the introduction of atomic layer deposition (ALD) technology and ultra-precision mold processing equipment, it plans to achieve mass production of solder wires with a diameter of 0.05 mm in the next two years, and develop ultra-fine solder balls with a diameter of less than 50 microns, providing key material support for cutting-edge fields such as 3D stacked packaging and quantum chips.

At the same time, enterprises are formulating an Industry 4.0 upgrade roadmap, realizing the intelligent interconnection of production equipment through IoT technology, building digital factories, and further improving product consistency and stability.

The development process of tin-based new materials is a microcosm of China's electronic materials industry from following to running and then leading the way. Nofil's technological breakthrough not only breaks the monopoly of foreign companies in the field of high-end solder materials, but also promotes our country's electronics manufacturing industry to move towards the high end of the value chain. In the future, with the continuous deepening of technological innovation, tin-based new materials will surely shine in more fields and contribute to the development of the global electronics industry.