PCB News - World SMB technology development trend, China is unstoppable

World SMB technology development trend, China is unstoppable

1. Use a new type of substrate
High-quality PCB substrates mainly have relatively large advantages in terms of heat resistance, size temperature, and electrical performance. This advantage can well meet the requirements of high-density mounting of electronic products. Chip-level substrates, that is, SMB substrates, can now be adapted to bare chip F.C mounting. These SMB substrates all improve its performance by modifying the original material or adding specific materials to it. Several new types of copper clad laminates for glass cloth machines will be introduced below.

New materials with low dielectric constant

As the current wireless communication is developing towards high frequency, all technologies require higher performance SMB boards. How to obtain SMB with low dielectric constant? The following will introduce two methods commonly used today.

(1) Use alkali-free glass fiber cloth: When using alkali-free glass fiber cloth, we will find that its low dielectric constant is only 60% of the CCL of ordinary glass fiber cloth.

(2) The use of new resins: It is understood that Japan has developed polyphenylene ether resin as the material for the insulating layer of the multilayer board. According to the test, the multilayer board has stable performance, low dielectric constant, and the maximum heating temperature is also significantly increased. Therefore, the polyphenylene ether substrate has been widely used in high-density packaging technology. For example, the substrate can be applied to automotive communications in the GHz field and mobile phones with high-frequency circuits.

2. FR-4 with high heat resistance
Due to the excellent comprehensive performance of FR-4 substrates, especially the high pass rate of metallized holes in the SMB manufacturing process, it has been widely used. The FR-4 base material that has appeared at present has the heat resistance of the polyimide base plate, but its processing technology is far better than that of the polyimide base plate, and it is cheaper.

(1) New substrate materials with thermal expansion coefficient: With the large-scale use of BGA, CPS, and FC, the thermal matching between PCB and device becomes more and more important. If the CTE difference between the two is large, it will cause cracks in the package connection, which reduces Installation quality and reliability. The company’s product MCL-E-679 developed in Japan and CEL-541 of New Kobe Click Co., Ltd. all use polyaramide fiber non-woven fabric as a reinforcing material to reduce the surface roughness of the substrate and contribute to CTE and low dielectric constant., And it is also suitable for laser drilling.

(2) Green substrates that meet the requirements of environmental protection: With the improvement of human environmental awareness, people pay more and more attention to the disposal of waste electronic products, because PCB substrates contain a large amount of bromine compounds, which will release harmful substances after burning --Dioxins are harmful to human health, so the environmental protection requirements for PCBs are getting higher and higher.

The flame retardants in SMB no longer use bromine compounds and antimony compounds, but instead use nitrogen and phosphorus compounds as flame retardants;
SMB production reduces low-molecular free phenols and free aldehydes to reduce volatiles and reduce CO2 emissions;
In the development of green substrate material products, it is necessary to maintain the environmental protection requirements of the substrate, but also to maintain the heat resistance, mechanical processability, mechanical strength and dimensional stability of the substrate, and the cost should not be greatly increased. .