The material that made Sora a success! How good is BMI resin?

Recently, the US Open AI Research Center released the first video generation model "Sora". The model can generate a 60-second short video by receiving text instructions. Chinese companies followed closely, and recently, the domestic Sora came! On March 5, at the Super Communication X Seven Volcanoes Conference, a high-definition 4K video of Wen Sheng amazed the audience.

Source: Weibo video screenshot

Do you know what is one of the core materials that has made great contributions to the manufacturing of Sora's servers? It is bismaleimide (BMI) resin.

01 What is BMI resin?

BMI resin is a type of polyimide (PI) resin . According to the synthesis method , PI resin can be divided into condensation type and addition type . BMI resin is a widely used addition type PI resin . BMI has a high content of benzene rings and imide heterocyclic rings and a high crosslinking density . The special structure of BMI gives it good heat resistance - the decomposition temperature is greater than 420°C, the long-term use temperature is 177-232°C, as well as high strength and modulus and high tolerance to various solvents, acids and water [1]. It is widely used in various fields, especially in the manufacture of artificial intelligence (AI) servers, playing the role of interconnection, insulation and support .

02 Wherever there is AI and big data models, there is BMI resin

So how does this material serve the high-frequency calculation of signals? First of all, Sora's model training requires large computing power support, and AI algorithms cannot be separated from AI servers.

Figure 1 Industrial chain diagram of printed circuit boards (created by the author)

As shown in the figure: Printed circuit board is one of the core components of AI server. It is a substrate for assembling electronic parts. It is mainly used to connect various electronic parts to form a predetermined circuit. It is known as the " mother of electronic products ". Printed circuit board is produced by copper clad laminate, ink, etching liquid, etc. Copper clad laminate is the basic material of the electronics industry and undertakes the three major functions of conductive, insulating and supporting printed circuit boards.

BMI resin is a high-frequency and high-speed resin with low dielectric constant, low dielectric loss, low thermal expansion coefficient and high thermal conductivity . It is often used as a raw material together with glass fiber cloth, wood pulp and copper foil to produce high-frequency and high-speed copper clad laminates, and its preparation process technology threshold is relatively high.

Figure 2: Finger-sized printed circuit board (copyrighted image from the gallery; reprinting may lead to copyright disputes)

Therefore, wherever AI and big data models are needed, BMI resins are present! For example, in the fields of computers, autonomous driving, intelligent machinery, intelligent medical devices, and aerospace . These fields are driving the rapid development of printed circuit boards, and at the same time, they are also driving the huge demand for high-frequency and high-speed resins.

From a cost perspective, high-frequency and high-speed resin accounts for about 25-30% of the production cost of copper clad laminates [2]. Given the rapid growth in demand for high-frequency and high-speed copper clad laminates, the cost of high-frequency and high-speed resin will also increase further!

03 Application in other fields

At the same time, BMI resin is also widely used in various fields:

1. Aerospace materials

Figure 3 C919, China's first civil aircraft with independent intellectual property rights (Source: Xinhuanet)

BMI resin can form carbon fiber reinforced composite materials with carbon fiber. This reinforced composite material is lighter than general traditional materials at the same strength. It is also adaptable to the surface temperature of the aircraft during flight and has a longer fatigue life. Among them, the domestically produced C919 passenger aircraft is the first domestic civil aircraft model to use T800-grade carbon fiber reinforced composite materials.

2. High temperature resistant insulation materials

Figure 4 Firefighters wearing fire suits participating in the 100-meter obstacle rescue competition (Source: Xinhuanet)

BMI resin can also be used as a raw material to make flame-retardant protective clothing with high temperature resistance. The flame-retardant mechanism is that when the protective clothing comes into contact with flames or high-temperature objects, it can slow down the spread of flames and form a carbonized isolation layer, thereby protecting personal safety and health. And it can quickly extinguish itself after leaving the flame, thus achieving the purpose of flame retardancy. Since the burning part will carbonize quickly and will not melt, drip or pierce, it is also beneficial for the user to quickly take off the protective clothing to avoid secondary injuries. The flame-retardant protective clothing is widely used in high-temperature industries such as firefighting, metallurgy, oil and gas .

Figure 5 Special adhesive resistant to high temperatures (copyrighted image from the gallery, reprinting may lead to copyright disputes)

BMI resin is widely used in the production of special adhesives due to its high temperature resistance. The adhesive can be used continuously at 260°C and also has good moisture and heat resistance, radiation resistance and insulation properties . In the fields of aviation, aircraft manufacturing and transportation machinery, it is widely used as a structural adhesive for connecting various alloy materials such as titanium alloys, aluminum alloys and inorganic non-metallic materials such as ceramics. The high-speed aircraft currently being developed in China also uses a large number of BMI resin-based composite materials, such as engine compartment skins and engine compartment longitudinal beam structures. The manufacture of these structural parts requires matching high-temperature resistant BMI adhesives, and the proportion of parts that need to be bonded is as high as 50%~60% (volume fraction) [4].

BMI resin can also be used as a raw material to prepare conductive adhesives with conductive particles, dispersing additives and additives . After curing, BMI resin will form a molecular network skeleton of the conductive adhesive, providing good mechanical support and ensuring bonding performance for the conductive adhesive. Conductive adhesive can connect a variety of conductive materials together to form an electrical path between the materials [3]. Based on this principle, efficient and reliable solar cells can be designed and prepared.

Figure 6 Solar photovoltaic panels (Source: Xinhua News Agency)

3. Insulation coating

Figure 7 Paints of different colors (copyrighted images from the gallery, reprinting may lead to copyright disputes)

In the field of coatings, BMI resin is mainly used as a base material component of insulating varnish. Insulating varnish is an insulating material based on high molecular polymers that can be cured into insulating films under certain conditions. It is composed of base materials, flame retardants, curing agents, pigments, and solvents [5]. This insulating varnish can undergo chemical reactions at room temperature to undergo cross-linking and curing, and has good properties such as heat resistance, chemical corrosion resistance, and mechanical impact resistance. In addition, the insulating varnish prepared from BMI resin is coated on the surface of the conductor to achieve an insulating effect, and electromagnetic wire can be prepared. Electromagnetic wire refers to an insulated wire used to make coils or windings, which can achieve energy conversion between electrical energy and magnetic energy through the principle of electromagnetic induction. It is generally used in electrical equipment such as transformers, various instruments, and motors.

4. Friction material

Using BMI resin as raw material, a series of new materials are introduced into the resin matrix as lubricating fillers to prepare BMI resin composite materials. This composite material has a low friction coefficient and excellent wear resistance. Some new graphene lubricating fillers can be combined with BMI resin to prepare BMI composite materials with good tribological properties, and can form a high-quality self-lubricating transfer film during the friction process, while having excellent bending strength and impact strength [6]. This new type of BMI composite material has certain potential in the field of friction and can be used in various automotive and aerospace parts.

summary

Nowadays, the demand for artificial intelligence, chips, 5G and even 5.5G base station construction is accelerating, driving a new round of scientific and technological revolution and industrial transformation, and driving the rapid development of the new materials industry. New materials represented by BMI resin are achieving "cross-border" integration and innovation with AI at an unprecedented speed. I believe that with the advancement of science and technology, these new materials will have greater potential in the AI ​​industry or cutting-edge industries such as deep space exploration and network security.

References:

1. Zhao Q, Li X, Tian Z, et al. Controlling degradation and recycling of carbon fiber reinforced bismaleimide resin composites via selective cleavage of imide bonds. Composites Part B: Engineering 2022; 231: 109595. https://doi.org/https://doi.org/10.1016/j.compositesb.2021.109595.

2. Wang Minghui et al. Electronic resin industry report 2: optimistic about the development of high-frequency and high-speed resins; Guojin Securities Co., Ltd.

3. Li Heping. Fine Chemical Technology (4th Edition). Science Press. 2023.

4. Yang Haidong, Wang Dezhi, Qu Chunyan, et al. Research progress of bismaleimide adhesives for aerospace applications[J]. New Chemical Materials, 2021, 49(10): 10-14. DOI: 10.19817/j.cnki.issn1006-3536.2021.10.003.

5. Zhou Yuqing. Composition, classification and use of insulating varnish[J]. Meishan Science and Technology, 2004(S2):20-24.

6. Shen Liangen, Shi Lei, Han Xiangpeng, et al. Tribological properties of modified graphene nanoribbon/bismaleimide composites [J/OL]. Fine Chemicals: 1-13 [2024-03-04]. https://doi.org/10.13550/j.jxhg.20230299.

Author: Gao Huang, PhD student in Materials Science, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences

Reviewer: Yuan Zhiqin, Professor of the School of Chemistry, Beijing University of Chemical Technology

Produced by: Science Popularization China

Produced by: China Science and Technology Press Co., Ltd., China Science and Technology Publishing House (Beijing) Digital Media Co., Ltd.