(September 20, 2026) As production expansions in domestic industries such as semiconductors, vacuum coating, commercial aerospace, and precision metallurgy continue to progress, vacuum diffusion pump oil – a key component in high-vacuum systems – faces both market demand and technological opportunities. Domestic high-performance diffusion pump oils are rapidly replacing imported products, addressing issues like thermal decomposition of the oil, backflow contamination, and short service life in high-vacuum conditions.

Vacuum diffusion pump oil is a crucial medium used by diffusion pumps to achieve high vacuum levels. It works through heating and vaporization, as well as high-speed injection, to remove gases. This oil is widely used in applications such as optical coating, photovoltaic cell manufacturing, electron microscopes, vacuum smelting, and aerospace environment simulation. There are two main types of products in this industry: mineral-based diffusion pump oil and synthetic silicone-based diffusion pump oil. Traditional mineral-based oil has lower costs, but it tends to decompose and produce carbon deposits at high temperatures, with a high risk of oil return. It is mainly used in basic vacuum processes. On the other hand, phenyl-synthetic diffusion pump silicone oil has a very low saturation vapor pressure and strong thermal stability; it does not produce carbon deposits during high-temperature operation, and it causes little contamination in the chamber. It can achieve high vacuum levels of 10⁻⁷Pa, making it the preferred choice for high-cleanliness environments such as semiconductors and precision research.

According to industry reports, the demand for diffusion pump oil in China will increase steadily in 2026. Customers’ purchasing criteria have changed significantly: they now focus on the oil’s ability to maintain high vacuum levels, its anti-oxidation properties, oil change intervals, and total cost of ownership. New production lines for photovoltaic HJT and TOPCon battery cells, as well as display panel coating facilities, continue to be built. Additionally, increased investment from domestic research institutions and aerospace testing platforms has led to rapid growth in demand for high-quality synthetic diffusion pump oil. In the past, high-level ultra-high vacuum applications relied heavily on imported oils. However, domestic silicone material manufacturers have made significant progress in improving oil purity, molecular weight control, and anti-backflow properties. Many domestic 704/705 series diffusion pump silicons have been tested for long-term stability by various vacuum equipment manufacturers, coating factories, and research institutions. Some products have already been supplied in bulk, effectively reducing the costs associated with material procurement and maintenance for domestic vacuum equipment manufacturers.

Technical experts in the industry say that the selection of diffusion pump oil directly affects the stability of the entire vacuum system. If the oil oxidizes or decomposes, it can lead to a decrease in the vacuum pressure and contamination of the chamber. This can result in a reduction in product quality or even the shutdown of the vacuum equipment. In semiconductor and optical coating processes where strict requirements are set, there are high standards for the metal impurities in the oil, its resistance to high-temperature evaporation, and its anti-aging properties. Domestic manufacturers are currently focusing on developing formulations that reduce oil return and create longer-lasting, anti-oxidizing systems, thereby narrowing the gap with international leading products.

Industry experts note that vacuum consumables represent a “small but critical” part of the high-end equipment industry. Continued advancements in domestic production of diffusion pump oil help to fill the gaps in supporting materials for vacuum equipment. In the future, as domestic precision manufacturing industries continue to develop, the market will further diversify: general-purpose mineral-based diffusion pump oil will remain in steady demand, while high-performance synthetic diffusion pump oil for ultra-high vacuum and long-term continuous operation will become the main source of growth. At the same time, manufacturers will also provide additional services such as oil testing, system maintenance, and technical support, shifting from simply selling consumables to offering comprehensive solutions for vacuum systems.

However, there are still challenges. In some highly clean ultra-high vacuum applications, there is room for further improvement in the long-term stability of domestic diffusion pump oil. The purification process for high-quality raw materials needs further refinement. With continued investment in the domestic silicone fine chemical industry, the rate of domestic production of vacuum diffusion pump oil is expected to increase, helping to ensure the autonomy of China’s entire vacuum equipment industry.