Substrate material is a base electronic component with good electrical insulation property, used for carrying electronic components and interconnecting wires. In general, substrate material should be equipped with excellent properties, such as good thermal conductivity, similar linear expansion rate to components, good high-frequency characteristics, high mechanical properties, good electrical insulation performance, stable chemical properties, and low cost. Besides, electrode materials are important components of electric devices, such as batteries, and can be seen in our daily life.
- Electronic packaging field: Electronic packaging is an important processing technology of integrated circuit, and substrate materials are essential constituent parts. With the acceleration of social informatization, the demands of substrate materials are rising.
- Electric devices field: Electrode materials are important parts of electric devices, which can convert chemical energy into electric energy. Electrode materials play an important role in our daily life, and are applied in most of the daily tools, such as mobile phones, computers, laptops and others.
- Ceramic substrates: Ceramic substrates have high insulation performance and excellent high frequency, similar linear expansion rate to components, high chemical stability and good thermal conductivity. This type of substrate materials, including Al2O3, AlN, SiC, and BeO, are widely applied in hybrid integrated circuit (HIC) and multi-chip module (MCM).
Figure 1 An example of ceramic substrates.
- Epoxy glass substrates: Epoxy glass is a composite material composed of epoxy resin and glass fiber. This type of material is often used in single-layer, double-layer or multi-layer printing plates.
- Diamond: Taking the advantages of high thermal conductivity, low dielectric constant, high resistivity and high breakdown voltage, diamond is an excellent substrate material for semiconductor device packaging.
- Insulating metal substrates: Insulating metal substrates have strengths in thermal conductivity, mechanical strength and processing performance, which mainly include Al (1100), Cu, Mo, W, invar and kovar.
- Metal matrix composites: In order to solve the shortcomings of single metal substrate materials, low expansion and high thermal conductivity metal matrix composites are researched and developed, mainly including copper matrix composites and aluminum matrix composites.
- LiCoO2 electrode materials: The discharge platform of LiCoO2 is about 4.2V, and theoretical discharge specific capacity is 272 mAh/g. The advantages of LiCoO2 is high working voltage, small self-discharge, excellent cycling performance. However, the main disadvantages of LiCoO2 cathode electrode materials are high cost, poor thermal stability, and circulatory capacity attenuation.
Figure 2 The crystal structure of LiCoO2.
- LiFePO4 electrode materials: Since olivine structure LiFePO4 was used as the electrode material, LiFePO4 has attracted much attention due to its advantages of stability, environmental protection and low price. Among them, the biggest advantage of LiFePO4 electrode materials is high safety.
Figure 3 The crystal structure of LiFePO4.
- LiMn2O4 electrode materials: LiMn2O4 crystal is spinel structure, belonging to cubic crystal system Fd3m space group. The three-dimensional ion channel structure is benefit to the rapid intercalation and de-intercalation of lithium ions. Moreover, due to the presence of manganese ions in each layer, the de-intercalation of lithium ions from the lattice structure will not cause structural changes, and the structural stability of the material is good.
Figure 4 The crystal structure of LiMn2O4.
- Carbon electrode materials: Carbon electrode materials are often used as anode material, mainly including graphene, carbon nanotubes. This type of material has the characteristics of heat resistance, corrosion resistance and large specific surface area, so it is an ideal electrode material.
- Metal-based electrode materials: The metal-based electrode materials mainly include metal, metal oxides, alloy materials, metal-carbon nanocomposite materials and alloy-carbon anode materials.
- Fei Liu, Shuyan Song, Dongfeng Xue, and Hongjie Zhang. Selective crystallization with preferred lithium-ion storage capability of inorganic materials[J] Nanoscale Research Letters. 2012, 7:149.