How to solve the pain points of sintering large ceramic parts and nitride substrates? ——Interview with Wei Guowen, general manager of Jiangsu Ruibang High-Temperature Products Co., Ltd.

In the semiconductor industry chain, key components represented by advanced ceramics are an important carrier to support the advanced manufacturing of semiconductor equipment, and are also an important area for domestic substitution. At the same time, the third generation of semiconductor materials represented by silicon carbide has shown extremely important strategic application value, among which silicon carbide single crystal preparation occupies the core position of the value chain. On April 25, the “Third Ceramic Materials Technology Seminar for the Semiconductor Industry and Third Generation Semiconductor SiC Crystal Growth Technology Exchange Conference” hosted by  Cnpowder was grandly opened in Suzhou, Jiangsu Province. During the meeting, we invited many experts and scholars to be guests in the "Dialogue" column and conducted interviews and exchanges around the application research of advanced ceramics in the semiconductor industry and silicon carbide single crystal growth technology and industrialization. What we share with you in this issue is an exclusive interview with Wei Guowen, general manager and technical director of Jiangsu Ruibang High-Temperature Products Co., Ltd.

Cnpowder: Hello, Mr. Wei, could you please briefly introduce Jiangsu Ruibang High-Temperature Products Co., Ltd.?

Mr. Wei: Our Jiangsu Ruibang High-Temperature Products Co., Ltd. is a company controlled by Suzhou Ruibang New Materials Co., Ltd., which was established in 2007. It is mainly engaged in the research and development, production and sales of high-tech porous ceramic kiln furniture. These ceramic kiln furniture are mainly used for the sintering of advanced ceramics. In 2009, we were attracted investment in Dafeng District, Yancheng, and established Jiangsu Ruibang High-Temperature Products Co., Ltd., still focusing on ceramic kiln furniture. By 2013, we began to develop sintering equipment.

Currently, our company has two workshop divisions. The first is the Ceramic Kiln Furniture Division, which mainly produces large ceramic pieces. The second division mainly produces atmosphere furnaces and electric-heated gas furnaces for sintering large ceramic pieces.

Cnpowder: Mr. Wei, would you highlight several distinctive equipment used in the advanced ceramics industry?

Mr. Wei: We have quite a lot of unique equipment. In the semiconductor field, we currently have two devices that are quite distinctive.
The first is an electric gas furnace for sintering large semiconductor parts. This electric furnace is different from ordinary electric furnaces. It was developed based on the sintering environment of gas furnaces. First, it has sufficient debinding power, and second, it has sufficient sintering efficiency. Third, it has the same capacity as a gas furnace. Therefore, this furnace has been used in many large-scale ceramic companies, and the demand for orders is very strong.
The second furnace serves the debinding of aluminum nitride and silicon nitride substrates. In the past, nitride debinding in our country used a vacuum method, which was detrimental to the cleanliness of the debinding and difficult to control. Cracking and warping problems often occurred. Based on the characteristics of organic molecules, we have developed an atmosphere thermal dehydration furnace. It is driven by hot air and active oxygen molecules at the front end and volatilized at the back end. It has been successfully used for debinding of silicon nitride substrates.

Cnpowder: Mr. Wei, you just mentioned the problem of cracking in large ceramic pieces. So what is the cause of cracking?

Mr. Wei: This is a systematic question, and it is also relatively professional. We have made some summaries based on 20 years of experience.
The first reason is of course the powder factor. There is no problem with the powder itself. The main reason is that after physical modification, the plasticity of the powder is required to be relatively high, and the granulated powder formed after modification is often hollow, very fine, and hard. This poses significant challenges for subsequent forming processes. For instance, the high hardness of the pellets necessitates substantial forming pressure. When pressure is released, the stress relaxation process becomes constrained. Compared to standard components, this stress release is inevitably slower. According to traditional Chinese ceramic experience, it is generally believed that isostatic pressure can be used to release the pressure directly after pressing. In fact, through numerous experiments, we have discovered that rapid pressure relief affects stress release in the product differently. There will be many invisible cracks on the oversized parts. If it is not discovered that cracking will occur if placed directly into the furnace, then many users will wonder whether there is something wrong with the furnace or the sintering curve? In fact, a good furnace can alleviate some of the defects that occur before entering the furnace, but it cannot absolutely solve them.
The furnace can only solve three problems. After an embryo body enters, it is divided into three steps: the first is for organic molecules, how to crack them and eliminate them to ensure that they will not crack during debinding. The second is the preheating process of ceramics, which must be completed before 1200°C. The third one is slow heating. The electric gas furnaces made by our company are completely configured for these three processes. For example, the most important process is debinding with slight negative pressure, which facilitates the volatilization of organic matter. This is akin to giving you a cup of boiling water that needs to evaporate. If I apply a force, it will evaporate more quickly. This furnace is currently widely used in the market and relatively successful. Compared to gas stoves, its advantages lie in its sufficient efficiency, high qualification rate, and highly flexible functionality and configuration.

Cnpowder: May I ask Mr. Wei how the company’s after-sales service is carried out?

Mr. Wei: Our after-sales service is actually relatively comprehensive and user-friendly. We primarily visit clients on-site to conduct thorough inspections and work with them to analyze why large parts crack and how to resolve the issue. Many problems arise before entry, such as how to select granulated powder, how to determine granulation powder, how to isostatically press some relatively large parts, how to change its program to obtain a complete embryo, and how to remove organic matter from our electric water and gas furnace, how to sinter it, and how to control the temperature?
voices of complaints. As an equipment manufacturer, we cannot guide a company to complete the production of the entire ceramic from scratch, so we understand and respect our customers. The company has always emphasized not to confront or deny customers, and to do our best to provide after-sales service.

Cnpowder: ‌ Alright, thank you for accepting our interview, Mr. Wei.