Classification and Applications of FR - 4 Material

General Classification of Substrate Applications:

Applications of Substrates:

1.Paper - based Phenolic Board
It includes XPC, XXXPC, FR - 1 and FR - 2, and is composed of phenolic resin and fiber paper.
XPC is usually applied in low - voltage/low - current consumer electronic products that do not cause fire sources, such as toys, portable radios, telephones, remote controls, etc.
The electrical properties and flame - retardancy of FR - 1 are better than those of XPC and can reach UL94V - 0 level. It can be widely used in electrical appliances with slightly higher voltage/current than XPC, such as color TVs, home stereos, washing machines, vacuum cleaners, etc.
XXXPC and FR - 2 have relatively better electrical properties and are used in roughly the same application fields.
The manufacturing process of the paper - based board is relatively simple. Through - holes can be processed by hot - punching or cold - punching methods, and copper plating can be achieved by printing silver paste or carbon ink.

2.CEM - I/CEM - 3
Glass cloth is used on the surface. The core of CEM - 1 is fiber paper, and the core of CEM - 3 is glass felt.
They are used in situations where phenolic paper - based boards cannot meet the requirements. Their electrical properties are better than those of phenolic paper - based boards, but worse than those of FR - 4 substrates.
For example, they are used in monitors, low - voltage power supplies, high - end stereos, game consoles, and some automotive circuits.
The manufacturing processes of CEM - 1 and CEM - 3 are similar to that of FR - 4, and even the cold - punching method can be used when the requirements are not high.

3.FR - 4 Material
It generally refers to the substrate with glass cloth base impregnated with epoxy resin.
White Material: Di - functional, with a Tg (glass - transition temperature) of about 125°C. Its electrical and mechanical properties are relatively weak and it is being phased out gradually.
Yellow Material: Multi - functional, with a Tg of about 135°C. It is widely used in civilian electronic equipment.
High Tg: FR - 4 with a Tg exceeding 155°C is generally called High Tg. Its reliability is higher than that of materials with ordinary Tg.
Modified FR - 4: Based on the conventional FR - 4 resin, higher electrical, mechanical properties and reliability are achieved by changing the formula or adding fillers. Under the premise of considering cost, it can be provided for higher - end products.
In addition, materials using other types of resins usually mix a certain proportion of epoxy resin to improve processability.

4.High - Performance Substrate
Other special/non - phenolic/non - FR - 4 resin - based substrates also include newly - developed materials such as Aramid and RCC.
It mainly refers to substrates composed of high - performance resins such as BT, PPO, Polyimide, Cyanate Ester, Hydrocarbon, Polyester, PTFE, etc. Usually, such substrates are added with ceramic fillers such as Ceramic and Kaolin.
They are mainly used in military or civilian communication equipment.
These substrates have excellent electrical, mechanical properties and high reliability, but their processability is worse than that of FR - 4.
With the development of HDI (High - Density Interconnect) technology, Aramid and RCC are widely used in the construction layers of Microvia.