Shulou(Shulou.com)11/24 Report--

Manufacturing industry is not only an important engine of China's economic growth, but also the main field of carbon emissions. As an important part of the manufacturing industry, the low-carbon development of the electronics industry has an important impact on the realization of carbon peak and carbon neutralization in China as a whole. In 2022, the Ministry of Industry and Information Technology, the National Development and Reform Commission and the Ministry of Ecological Environment jointly issued the implementation Plan for carbon Peak in the Industrial sector, supporting leading enterprises in electronics and other industries to play a leading role in key areas such as supply chain integration and innovative low-carbon management. the green and low-carbon concept runs through the whole process of product design, raw material procurement, production, transportation, storage, use and recycling.

In recent years, due to the popularity of high performance computing and artificial intelligence calculus, facing the requirements of high efficiency and high bandwidth, low power consumption, multi-chip integration and spatial integration equipment, as well as the active implementation of environmental protection carbon neutralization related policies, the use of low-temperature solder and lead-free low-temperature welding process (Low Temperature Soldering, referred to as LTS) has become the focus of public attention. As soon as it was pushed out, it was adopted by the industry, effectively solving the "three high" problems of high heat, high energy consumption and high carbon dioxide emissions that plagued the manufacturing process of electronic products for more than ten years.

The lead-free booster low temperature welding process for electronic materials arises at the historic moment.

Alloy solder is the most critical electronic packaging material in the welding process of the electronic industry. It welds IC, discrete devices and passive components on the printed circuit board through solder to achieve the most basic functions of electronic products. Every day, a large amount of solder paste made of alloy solder is consumed in the production line of electronic products. at the same time, the heat, energy consumption and carbon emissions in this process can not be effectively controlled.

However, at the beginning of this century, the medium-temperature solder with tin and lead as the main composition is still in the mainstream manufacturing process in the electronic industry, but because of the high content of lead, it is harmful to health without protection for a long time, and it is not environmentally friendly. The WEEE (Directive on scrapping Electrical and Electronic equipment) and RoHS (Directive on restricting the use of certain harmful components in Electrical and Electronic equipment) issued by the European Union in 2003 came into effect, resulting in the first mandatory ban on the use of lead and limited use of halogen in electronic products. The measures for the Prevention and Control of pollution in the production of Electronic Information products drawn up by the Ministry of Information Industry of China proposes that from July 1, 2006, electronic information products in the key national regulatory catalogue put on the market should not contain lead. The welding process of electronic assembly is transferred from lead solder (SnPb) to lead-free solder. The change wave of lead-free electronic materials is also on the rise, at the same time, practitioners began to invest in the research and development of lead-free solder and mass production.

According to experts, at present, there are five series of lead-free alloy solders widely used in the world, namely, Sn-Ag series, Sn-Cu series, Sn-Bi series, Sn-In series and Sn-Zn series. It can be divided into three types according to the melting point: high temperature solder (melting point above 200 °C), medium temperature solder (melting point 180 °C-200 °C) and low temperature solder (melting point less than 180 °C).

In the process of transition from lead-free solder to lead-free solder, tin-silver-copper (Sn-Ag-Cu) alloy solder has the advantage of no nitrogen welding environment because of its high welding temperature, but its comprehensive cost is low. After nearly 10 years of application, tin-silver-copper alloy solder has been widely used in most enterprises.

In fact, as an important basic material of low temperature welding technology, low temperature solder has more than 20 years of industrial research and application history, and has become a widely recognized standardized alloy solder in the industry. As early as 2006, low temperature solders were clearly defined and required by IPC J-STD-006C-2013 of IPC, JIS Z 3282-2006 of JIS and ISO9453-2006 of ISO.

Requirements of IPC J-STD-006C-2013 for Sn-In series and Sn-Bi series low temperature solder alloys

Low temperature solder series specified by JIS Z 3282-2006

Requirements of ISO9453-2006 for Bi58Sn42 low temperature solder

The International Federation of Electronics Manufacturers (iNEMI- International) launched a research project on low temperature welding process and reliability based on tin and bismuth in 2015, and developed a series of evaluation and application standards. At the same time, many domestic tin paste manufacturers have also developed more low-temperature tin paste based on tin-bismuth alloy.

According to reports, after years of development, testing, evaluation and application in the industry, the commercial proportion of Sn-Bi low-temperature welding technology continues to expand and improve in the field of consumer electronics. More than 10 years ago, low-temperature welding technology has been widely used in the low-temperature assembly scene of heat-sensitive electronic components such as LCD / LED display screen, high-frequency head, lightning protection components, temperature control elements, flexible plates and so on.

Obvious advantages in low-temperature tin paste process to become a new force for carbon reduction

The 2009 climate summit in Copenhagen proposed the Greenhouse Gas (GHG) global greenhouse gas emissions inventory. The Chinese government promised at the United Nations Climate change Summit that "China will further integrate climate change into its economic and social development planning and continue to take strong measures." Under the circumstances that "carbon neutralization" has increasingly become a new global political identity and a game tool of international political and economic interests, the "3060" goal put forward by China in 2021 has brought about new and profound changes in the global political and economic pattern. On the one hand, the goal of "carbon neutralization" puts forward higher requirements for the transformation and development of carbon reduction of enterprises, on the other hand, it creates a huge new opportunity for green investment for the whole market.

In 2017, under the guidance of the Ministry of Industry and Information Technology, China Green Manufacturing Alliance was formally established. For dozens of the world's top 500 enterprises and more than 100 enterprises and institutions covering iron and steel, chemical, building materials, power, energy, machinery, light industry, electronic information and other industries, full affirmation and support for low temperature welding technology.

At present, the low temperature solder widely used in the market is tin bismuth Sn-Bi binary alloy. Compared with the melting point of 220C of high temperature solder, the melting point of low temperature solder Sn-Bi is 139 °C and can be welded below 185C, which reduces the welding peak temperature by 60 ℃, which greatly improves the welding reliability defects caused by thermal stress and chip warping risk during reflow soldering, and reduces the energy consumption in SMT assembly process by more than 20%. Reduced a lot of carbon dioxide emissions.

According to industry experts, the research and application of new welding technology is not limited to the replacement of welding materials, it is a very complex system engineering, it needs to meet the performance requirements of the product at the same time, according to the characteristics of the solder alloy to carry out all aspects of technical research, involving the development and research of welding basic materials, design changes of product design, selection and matching of various components, adjustment and optimization of manufacturing process. The formulation of test means / methods / standards (electrical performance, reliability) requires a lot of research and test work of many relevant researchers, designers and engineers. A large number of experimental results for many years show that the low temperature welding accords with the standard of IPC-A-610G / H version B and meets the reliability function requirements of the product, which ensures that the new welding technology can be applied smoothly and reliably.

With the popularity of carbon reduction actions, the electronics industry has begun to formulate low-carbon related strategies, comprehensively entering the era of energy saving and carbon reduction. In addition, according to the International Federation of Electronic Manufacturers (iNEMI), the market share of products using low-temperature welding processes will increase from about 1 per cent to more than 20 per cent by 2027. Effectively reducing carbon dioxide emissions in the production process, greatly improving the welding reliability defects caused by thermal stress in the welding process, and reducing production costs have become the three killer mace of low-temperature welding process. at the same time, it also adds a new force to slow down global warming and promote carbon neutralization.

The development and application of new technologies, new materials, new processes and new products are not only in line with people's pursuit of a better life, but also the driving force for the everlasting business of enterprises.

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