What are the semiconductor chip packaging materials?

Semiconductor chip packaging materials refer to materials used for semiconductor chip packaging. Its main function is to protect the chip from erosion by the external environment and provide support, heat conduction, insulation and other functions for the chip.

There are many types of semiconductor chip packaging materials. According to their main materials, they can be divided into metal materials, plastic materials, ceramic materials, glass materials, etc.

Metallic material

Metal materials have good thermal conductivity, strength and corrosion resistance, and are a common choice for semiconductor chip packaging materials. Commonly used metal packaging materials include aluminum, copper, silver, gold, etc.

Aluminum

Aluminum is a lightweight, highly thermally conductive metal that is cost-effective and is the preferred packaging material for semiconductor chips. Aluminum packaging materials are mainly used for low-power, small, and thin chip packaging.

Aluminum as a semiconductor packaging material has the following advantages:

• It is light in weight and has a density of 2.7g/cm3, which is only 1/3 of copper, which helps reduce the weight and volume of the chip.
• It has good thermal conductivity, with a thermal conductivity of 200W/(m·K), second only to silver and 2/3 of copper.
• Low cost, the price is only 1/5 of copper.

Aluminum as a semiconductor packaging material also has the following disadvantages:

• Low strength, the tensile strength is 90MPa, which is only 1/4 of copper.
• It has poor corrosion resistance and is easily corroded by acids, alkalis, etc.

Copper ( Cuprum )

Copper has higher thermal conductivity and strength, but also costs more. Copper packaging materials are mainly used for high-power and high-power chip packaging.

Copper has the following advantages as a semiconductor packaging material:

• It has good thermal conductivity and the thermal conductivity is 400W/(m·K), which is twice that of aluminum.
• High strength, the tensile strength is 200MPa, which is 2.2 times that of aluminum.
• It has good corrosion resistance and can resist acid, alkali and other corrosion.

Copper as a semiconductor packaging material also has the following disadvantages:

• It is heavier and has a density of 8.9g/cm3, which is 3 times that of aluminum.
• The cost is high, the price is only 2 times that of aluminum.

Silver ( Argentum )

Silver has the highest thermal conductivity, but is also the most expensive. Silver packaging materials are mainly used for chip packaging that require extremely high thermal conductivity, such as power amplifiers, radio frequency chips, etc.

Silver has the following advantages as a semiconductor packaging material:

• It has good thermal conductivity, with a thermal conductivity coefficient of 430W/(m·K), which is 1.07 times that of copper.
• High conductivity, 63.5S/m, 1.62 times that of copper.
• High gloss and good decorative properties.

Silver also has the following disadvantages as a semiconductor packaging material:

• It is heavier and has a density of 10.5g/cm3, which is 4 times that of aluminum.
• The cost is high, the price is only 10 times that of aluminum.

Gold ( Aurum )

Many people know the chemical symbol for gold is “Au”, but not as many people know the origin of the term, or why the atomic number for gold is 79, or where the word gold comes from.

Gold has good electrical conductivity, corrosion resistance and aesthetics, and is mainly used for high-end, high-performance chip packaging.

Gold has the following advantages as a semiconductor packaging material:

• It has good electrical conductivity, with a conductivity of 41.7S/m, which is 1.67 times that of copper.
• It has good corrosion resistance and can resist acid, alkali and other corrosion.
• It has good aesthetics and good decorative properties.

Gold also has the following disadvantages as a semiconductor packaging material:

• The cost is high, the price is only 100 times that of aluminum. Gold is expensive due to its reserves and difficulty in mining, which increases the cost of semiconductor packaging.
• Difficulty in processing: Gold has a high hardness, which makes it prone to wear and scratches during processing, resulting in a reduction in packaging yield.
• Poor heat dissipation performance: Gold is a poor conductor with poor thermal conductivity, which is not conducive to heat dissipation of semiconductor devices.
• Insufficient ductility: Gold is prone to deformation when subjected to high temperatures or external forces, affecting the accuracy and reliability of packaging.

Although gold has some shortcomings as a semiconductor packaging material, it still has irreplaceable advantages in some fields, such as high conductivity, high chemical stability and good corrosion resistance. In practical applications, appropriate packaging materials need to be selected according to specific needs to achieve optimal performance and cost-effectiveness.

Plastic material

Plastic materials have good insulation, mechanical strength and processability and are another common choice for semiconductor chip packaging materials. Commonly used plastic packaging materials include epoxy resin, polyimide, polytetrafluoroethylene, etc.

Epoxy resin

Epoxy resin is a commonly used plastic packaging material with good insulation, mechanical strength and processability. Epoxy resin packaging materials are mainly used for low-power, small, and thin chip packaging.

Polyimide

Polyimide is a high-performance plastic packaging material with good heat resistance, corrosion resistance and high-frequency performance. Polyimide packaging materials are mainly used for high-power, high-frequency, and high-reliability chip packaging.

PTFE

PTFE is a plastic packaging material with good corrosion resistance, high temperature resistance and low friction. PTFE packaging materials are mainly used for chip packaging that require extremely high corrosion resistance and high temperature resistance, such as power amplifiers, radio frequency chips, etc.

Ceramic material

Ceramic materials have good heat resistance, corrosion resistance and mechanical strength, and are an important choice for semiconductor chip packaging materials. Commonly used ceramic packaging materials include alumina, silicon nitride, Si3N4, etc.

Alumina

Aluminum oxide is a commonly used ceramic packaging material with good heat resistance, corrosion resistance and mechanical strength. Alumina packaging materials are mainly used for high-power, high-frequency, and high-reliability chip packaging.

silicon nitride

Silicon nitride is a ceramic packaging material with higher heat resistance, corrosion resistance and mechanical strength. Silicon nitride packaging materials are mainly used for chip packaging that require extremely high heat resistance and corrosion resistance, such as power amplifiers, radio frequency chips, etc.

Si3N4

Si3N4 is a ceramic packaging material with good heat resistance, corrosion resistance and mechanical strength. Si3N4 packaging materials are mainly used for high-frequency, high-reliability chip packaging.

Glass material

Glass material has good heat resistance, corrosion resistance and light transmittance, and is a special choice for semiconductor chip packaging materials. Commonly used glass packaging materials include quartz glass, borosilicate glass, etc.

Quartz glass

Quartz glass is a glass packaging material with good heat resistance, corrosion resistance and light transmittance. Quartz glass packaging materials are mainly used for chip packaging that require extremely high heat resistance, corrosion resistance and light transmittance, such as optical chips, lasers, etc.

Borosilicate glass

Borosilicate glass is a glass with low thermal expansion coefficient, high heat resistance, high chemical stability and high optical transmittance. Its main components are silicon dioxide (SiO2), boron oxide (B2O3) and sodium oxide (Na2O). Among them, the content of boron oxide is between 6% and 15%, which is the main factor that determines the performance of borosilicate glass.
Low thermal expansion coefficient is one of the distinctive features of borosilicate glass. Its thermal expansion coefficient is about 1/3 of ordinary glass, so it has good thermal shock resistance and can withstand large temperature changes. This allows borosilicate glass to maintain its shape and properties at high temperatures, making it ideal for applications that need to withstand high temperatures, such as electric heaters, cookware, optical instruments, etc.
High heat resistance is another important feature of borosilicate glass. Its softening point temperature is about 1000°C, which is much higher than the softening point temperature of ordinary glass. Therefore, borosilicate glass can be used at high temperatures for a long time and has good corrosion resistance.
High chemical stability is one of the important properties of borosilicate glass. It has good corrosion resistance to chemicals such as acids, alkalis, and salts, so it can be used in various chemical environments.
High optical transmittance is another advantage of borosilicate glass. Its optical transmittance can reach over 90%, making it very suitable for optical applications.
Borosilicate glass has the above-mentioned excellent properties, so it has been widely used in semiconductor chip packaging. It is mainly used in the following areas:
High temperature packaging: Borosilicate glass has good heat resistance and can be used for high temperature packaging, such as power device packaging, LED packaging, etc.
Chemical packaging: Borosilicate glass has good chemical stability and can be used for chemical packaging, such as liquid crystal display packaging, optoelectronic device packaging, etc.
Optical packaging: Borosilicate glass has good optical transmittance and can be used for optical packaging, such as optical fiber packaging, laser packaging, etc.
In recent years, with the continuous development of semiconductor technology, the performance requirements for chip packaging materials have become increasingly higher. Borosilicate glass will continue to maintain its important position in the field of semiconductor chip packaging due to its excellent properties.