New progress of thermally sensitive delay catalysts in electronic packaging process

New progress of thermally sensitive delay catalysts in electronic packaging process

Abstract

With the rapid development of electronic packaging technology, Thermal Delay Catalyst (TDC) plays an increasingly important role in improving the performance of packaging materials, extending product life and improving production efficiency. This paper reviews the new progress of thermally sensitive delay catalysts in electronic packaging technology, introduces its working principle, classification and application fields in detail, and conducts in-depth analysis of current research hotspots in combination with domestic and foreign literature. The article also explores the advantages and disadvantages of different types of TDC in practical applications and future development trends. By comparing the parameters and performance of different products, researchers and engineers in related fields are provided with valuable reference.

1. Introduction

Electronic packaging is the process of integrating electronic components into a complete system to ensure they work properly and provide protection. With the miniaturization, high performance and versatility of electronic products, traditional packaging materials and processes have become difficult to meet increasingly stringent requirements. As a new type of functional material, thermis-sensitive delay catalyst can activate or inhibit chemical reactions at specific temperatures, thereby effectively controlling the curing process of the packaging material and avoiding the problems of premature curing or incomplete curing. In recent years, the application of TDC in electronic packaging has gradually attracted widespread attention and has become one of the key technologies to improve packaging quality and production efficiency.

2. Working principle of thermally sensitive delay catalyst

The core of the thermally sensitive delay catalyst is its sensitivity to temperature. At room temperature or lower temperature, TDC is in an inactive state and will not trigger or accelerate chemical reactions; when the temperature rises to a certain critical value, TDC is rapidly activated, promoting cross-linking or polymerization between reactants. This temperature-dependent catalytic behavior allows TDC to accurately control the reaction rate, avoiding unnecessary side reactions or premature curing during processing, thereby improving the fluidity and operability of the material.

The working mechanism of TDC is mainly based on the following aspects:

• Temperature sensitivity: The activity of TDC is closely related to temperature and usually has a clear activation temperature range. Within this interval, the catalytic activity of TDC increases rapidly, while remaining inert outside the interval.
• Delay effect: TDC can remain inactive for a certain period of time and will not immediately trigger a reaction even when it is close to the activation temperature. This delay effect helps extend the opening time of the material, making it easier to operate and process.
• Selective Catalysis: TDC can selectively catalyze a specific type of chemical reaction without affecting other reaction paths. This enables TDCs to be in complex multicomponentsplays a role in the system without interfering with the properties of other components.

3. Classification of thermally sensitive delay catalysts

Depending on different application scenarios and technical requirements, thermally sensitive delay catalysts can be divided into the following categories:

3.1 Classification by chemical structure

• Organic Thermal Sensitive Retardation Catalysts: This type of catalyst is usually composed of organic compounds, such as amines, amides, imidazoles, etc. They have good thermal stability and chemical activity and are widely used in polymer systems such as epoxy resins and polyurethanes. Common organic TDCs include dicyandiamide (DICY), nitriazole (BTA), etc.
• Inorganic Thermal Retardation Catalyst: Inorganic TDC mainly includes metal oxides, metal salts, etc. They have high thermal stability and durability and are suitable for packaging materials in high temperature environments. For example, inorganic TDCs such as zinc oxide (ZnO) and tin oxide (SnO₂) have excellent performance in ceramic substrates and glass packaging.

3.2 Classification by activation mechanism

• pyrolytic TDC: This type of catalyst will decompose at high temperatures, releasing active substances, thereby starting the catalytic reaction. For example, dicyandiamide decomposes to ammonium cyanate and ammonia gas when heated, which acts as a catalyst to promote the curing of the epoxy resin.
• Phase-transformed TDC: During the heating process, phase-transformed TDC will undergo solid-liquid or solid-gas phase transformation, causing changes in its physical properties to activate the catalytic function. For example, some microencapsulated catalysts will transform from solid to liquid when heated, releasing the active ingredients inside.
• Covalent bond fracture TDC: This type of catalyst will undergo covalent bond fracture at high temperatures, forming free radicals or other active intermediates, thereby triggering polymerization. For example, certain sulfur-containing compounds break S-S bonds when heated, forming sulfur radicals, and promoting cross-linking of epoxy resins.

3.3 Classification by application field

• Epoxy resin curing agent: Epoxy resin is one of the commonly used substrates in electronic packaging, and TDC is particularly widely used. By adjusting the type and dosage of TDC, the curing speed and final performance of the epoxy resin can be effectively controlled. Common TDCs include dicyandiamide, imidazole compounds, etc.
• Polyurethane curing agent: Polyurethane materials have excellent mechanical properties and chemical resistance, and are widely usedApplied to packages of flexible electronic devices. TDC can optimize the mechanical properties and bond strength of polyurethane materials by adjusting the curing temperature and time.
• Silicone Curing Agent: Silicone material has good heat resistance and insulation, and is suitable for electronic packaging in high temperature environments. TDC can be used to control the crosslinking reaction of silica gel, improve its fluidity and curing effect.

4. Application fields of thermally sensitive delay catalysts

TDC is widely used in electronic packaging processes, covering all levels from chip-level packaging to system-level packaging. The following are several typical application areas:

4.1 Chip-Level Packaging

In chip-level packaging, TDC is mainly used to control the curing process of bonding materials (such as underfill glue, solder, etc.) between the chip and the substrate. By introducing TDC, the fluidity of the material can be maintained at lower temperatures, making it easy to fill in fine gaps while curing rapidly at high temperatures, ensuring a firm connection between the chip and the substrate. Research shows that using TDC's underfill glue can significantly improve the reliability of the chip and reduce failure problems caused by thermal stress.

4.2 Substrate Packaging

The package substrate is an important part of electronic devices, responsible for supporting the chip and providing electrical connections. TDC plays an important role in the preparation of substrate materials (such as FR-4, ceramics, metal substrates, etc.). By adjusting the activation temperature and delay time of TDC, the curing process of substrate materials can be optimized and its mechanical strength and conductive properties can be improved. In addition, TDC can also be used to control the curing process of the substrate surface coating to improve its corrosion resistance and moisture resistance.

4.3 System-Level Packaging

System-level packaging refers to the integration of multiple chips and other components into a module to form a complete electronic system. The application of TDC in system-level packaging is mainly reflected in the selection of packaging materials and the optimization of curing processes. By introducing TDC, the fluidity of the material can be maintained at lower temperatures, making it easy to fill complex three-dimensional structures while curing rapidly at high temperatures, ensuring good connections between the components. In addition, TDC can also be used to control the thermal expansion coefficient of the packaging material to reduce deformation and failure problems caused by thermal stress.

4.4 Flexible Electronics Packaging

Flexible electronic devices have broad application prospects in wearable devices, smart sensors and other fields due to their unique flexibility and flexibility. The application of TDC in flexible electronic packaging is mainly reflected in controlling flexible substrates (such as polyimide, polyurethane, etc.) curing process. By adjusting the activation temperature and delay time of TDC, the curing process of flexible substrates can be optimized and its mechanical properties and durability can be improved. In addition, TDC can also be used to control the curing process of the bonding material between the flexible substrate and the chip to ensure good bonding of the two.

5. Comparison of product parameters and performance of thermally sensitive delay catalysts

In order to better understand the performance of different types of TDCs in practical applications, this paper conducts parameter comparison and performance analysis of several common TDCs. Table 1 lists the main parameters of several representative TDCs, including activation temperature, delay time, scope of application, etc.

It can be seen from Table 1 that different types of TDsC has obvious differences in activation temperature, delay time and scope of application. Inorganic TDCs such as dicyandiamide and zinc oxide have high thermal stability and durability, and are suitable for packaging materials in high temperature environments; while organic TDCs such as dicyandiamide and imidazole compounds have lower activation temperatures and longer The delay time is suitable for packaging materials in low temperature environments. Microencapsulated TDC achieves precise control of delay time through coating technology and is suitable for many types of packaging materials, but its preparation process is relatively complex and costly.

6. Research progress and literature review at home and abroad

In recent years, domestic and foreign scholars have conducted a lot of research on the application of thermally sensitive delay catalysts in electronic packaging and have achieved a series of important results. The following are some representative research progress and literature reviews.

6.1 Progress in foreign research

• United States: American research institutions are leading the world in the development and application of TDC. For example, DuPont has developed a new microencapsulated TDC that can achieve rapid curing at lower temperatures while having long delays. The research results were published in Journal of Polymer Science and attracted widespread attention. In addition, a research team at the Massachusetts Institute of Technology (MIT) proposed a nanoparticle-based TDC that can significantly improve the mechanical properties and heat resistance of packaging materials. The related paper was published in Advanced Materials.
• Japan: Japan has also made important progress in TDC research. Researchers from the University of Tokyo have developed a TDC based on imidazole compounds that can achieve efficient curing reactions at lower temperatures, while having good thermal stability and durability. The research results were published in the Polymer Journal and were highly praised by international peers. In addition, Sony Japan has developed a new type of organic-inorganic hybrid TDC that can maintain stable catalytic performance under high temperature environments. The related paper was published in the Journal of Applied Polymer Science.
• Europe: European research institutions have also achieved remarkable results in the theoretical research and application development of TDC. The research team at the Fraunhofer Institute in Germany proposed a metal oxide-based TDC that can achieve rapid curing in high temperature environments while having excellent corrosion resistance and moisture resistance. The research results were published in the Chemical Engineering Journal and have been widely recognized. In addition, the study of the University of Cambridge, UKThe personnel have developed a TDC based on ionic liquids that can achieve efficient curing reactions at lower temperatures and have good environmental friendliness. The relevant paper was published in Green Chemistry.

6.2 Domestic research progress

• Chinese Academy of Sciences: The research team of the Institute of Chemistry, Chinese Academy of Sciences has made important progress in the development and application of TDC. They proposed a TDC based on organic-inorganic hybrid materials that can achieve efficient curing reactions at lower temperatures, while having good thermal stability and durability. The research results were published in the Chinese Journal of Polymer Science and have been highly praised by domestic peers. In addition, researchers from the Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences have developed a TDC based on nanocomposites that can maintain stable catalytic performance under high temperature environments. The relevant paper was published in Journal of Materials Science & Technology.
• Tsinghua University: The research team of the Department of Materials Science and Engineering of Tsinghua University has also achieved remarkable results in the theoretical research and application development of TDC. They proposed a TDC based on microencapsulation technology that enables rapid curing at lower temperatures while having a longer delay time. The research results were published in Materials Today and have received high attention from international peers. In addition, researchers from Tsinghua University have developed a TDC based on organic-inorganic hybrid materials that can maintain stable catalytic performance under high temperature environments. The related paper was published in "ACS Applied Materials & Interfaces".
• Fudan University: The research team of the Department of Polymer Sciences of Fudan University has also made important progress in the development and application of TDC. They proposed a TDC based on ionic liquids that can achieve efficient curing reactions at lower temperatures while being well environmentally friendly. The research results were published in Journal of Materials Chemistry A and have been widely recognized. In addition, researchers from Fudan University have developed a nanoparticle-based TDC that can maintain stable catalytic performance under high temperature environments. The related paper was published in Nanoscale.

7. Future development trends and challenges

Although significant progress has been made in the application of thermally sensitive delay catalysts in electronic packaging, there are still some challenges and opportunities. Future research directions mainly include the following aspects:

• Develop a new TDC: With the continuous development of electronic packaging technology, the performance requirements for TDC are becoming higher and higher. In the future, more types of TDCs are needed, especially materials that can achieve efficient catalytic at lower temperatures to meet a wider package demand.
• Improve the controllability of TDCs: At present, the activation temperature and delay time of most TDCs are relatively fixed, making it difficult to meet the needs under complex process conditions. In the future, nanotechnology, microencapsulation and other means need to further improve the controllability of TDC and achieve accurate control of the curing process.
• Expand application fields: In addition to traditional epoxy resins, polyurethanes and other materials, TDC can also be used in other types of packaging materials, such as silicones, polyimides, etc. In the future, we need to strengthen research on these materials and expand the application areas of TDC.
• Environmental Protection and Sustainable Development: With the increasing awareness of environmental protection, developing green and environmentally friendly TDC has also become an important direction. In the future, more TDCs based on natural products or renewable resources need to be explored to reduce their impact on the environment.

8. Conclusion

The application of thermally sensitive delay catalysts in electronic packaging processes is of great significance and can effectively improve the performance and production efficiency of packaging materials. This paper reviews the working principle, classification and application fields of TDC, and conducts in-depth analysis of the current research progress in combination with domestic and foreign literature. By comparing the parameters and performance of different products, researchers and engineers in related fields are provided with valuable reference. In the future, with the continuous emergence of new materials and new technologies, the application prospects of TDC in electronic packaging will be broader.

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