Composite Materials for Electronic Packaging

Release time:


Composite materials are composed of two or more different materials, which can have the comprehensive properties of different materials. At present, there are three main types of composite materials in the field of electronic packaging.

(1) Polymeric matrix composites.

The thermal conductivity of the polymer is low, and the thermal conductivity of the polymer can be improved by filling the inorganic filler with high thermal conductivity. Epoxy resin has poor thermal conductivity, and its thermal conductivity can be improved by adding high thermal conductivity fillers. In addition to fillers, coupling agents and curing agents are also important additives in epoxy resin-based composites.

(2) Ceramic matrix composites.

The advantages of this type of material are:

Low dielectric constant, high frequency application performance is stable;

② Good insulation performance;

High mechanical strength and good heat resistance;

④ Low thermal expansion coefficient and high thermal conductivity;

⑤ Good air tightness, good chemical stability and high reliability;

The moisture absorption rate is low, more difficult to occur micro-cracking phenomenon. However, the ceramic process is complex and the cost is high, and it is suitable for advanced microelectronic device packaging, as well as high reliability, high temperature resistance, and strong air tightness.

(3) Metal matrix composites (MMC).

Metal materials have excellent thermal conductivity, adding low expansion coefficient of reinforced phase materials to metal matrix materials, complementary advantages, can be obtained to meet the thermal conductivity requirements and meet the thermal expansion coefficient matching requirements of composite materials, expand the application range of materials in the field of packaging. The thermal conductivity of metal W and Mo-based composites can reach 150~230W/(m · K), and the thermal expansion coefficient is 5.7 × 10-6~10 × 10-6/K, which belongs to the traditional metal-based electronic packaging materials, but its high cost, poor solderability and high density are not conducive to the application scenarios that require quality. Al,Cu,Ag matrix composites not only have relatively low density, but also have higher thermal conductivity than W,Mo matrix composites. Al,Cu,Ag-based electronic packaging composites are mainly divided into Si C, Si, carbon fiber and diamond according to the reinforcement. The high volume fraction Si Cp/ Al composite has excellent comprehensive properties: higher thermal conductivity, adjustable thermal expansion coefficient, higher strength and hardness, and lower density. This makes it an ideal material in the field of electronic packaging, especially in aerospace and optoelectronic devices where the application environment is more demanding. However, the high volume fraction of Si Cp/Al composite material also has the disadvantage of restricting its development: high cost, difficult process (especially difficult to carry out secondary machining), which limits the wide application of the material. Since diamond has the highest thermal conductivity of all substances (700~2000W/(m · K)), the density is only 3.48~3.54g/cm3; the use of diamond particles and Cu or Al composite, through a specific process can be produced by the volume fraction of R & D. For electronic packaging composite materials, improving the interfacial bonding between the reinforcing phase and the matrix and reducing the thermal resistance between the two are always issues that need to be studied in depth. The thermal conductivity of Si Cp/ Al composites is 150~200W/(m · K) and the density is only about 3.0g/cm3, while the thermal conductivity and thermal expansion coefficient of diamond/Cu composites can reach 600~700W/(m · K) and 6 × 10-6~8 × 10-6/ K, respectively.

Metal matrix composites can effectively match metal materials and ceramic materials, which not only meet the requirements of thermal conductivity but also meet the requirements of thermal expansion coefficient matching, so as to obtain the comprehensive performance of the components of composite materials, which is a kind of composite materials with earlier research and more perfect theoretical explanation. Metal matrix composites include Si C /Al particle reinforced composites, W/Cu and C /Cu composites, and flat plate composites CIC (Cu /Invar/Cu), CMC (Cu/Mo /Cu), CPC (Cu/Mo Cu / Cu) and CKC (Cu /Kovar/Cu). Among them, the research of Si C /Al composites is earlier, and the theoretical explanation is more perfect.