When digital signals are transmitted on the board, the characteristic impedance value of the PCB must match the electronic impedance of the head and tail components; once mismatched, the transmitted signal energy will be reflected, scattered, attenuated or delayed; in this case, impedance control must be performed so that the characteristic impedance value of the PCB matches the components.
2, HDI blind buried holes
Blind holes are only visible in the one of the top or bottom layer; buried holes are in the inner layer, the upper and lower sides of the hole are in the internal layer of the board. The application of blind buried holes, greatly reduce the size and quality of HDI (High Density Interconnect) PCB, reduce the number of layers, improve electromagnetic compatibility, reduce costs, while also making the design work easier and faster.
3, Thick copper board
Bonding a layer of copper foil in the FR-4 outer layer, when the finished copper thickness ≥ 2oz, defined as a thick copper board. Thick copper PCB has excellent extension performance, high and low temperature resistance, corrosion resistance, so that electronic products have a longer service life, and the volume of the product is greatly helped to minimize.
4，multi-layer special laminated structure
Laminated structure is an important factor affecting the EMC performance of the PCB board, but also an important means of suppressing electromagnetic interference. The more the number of signal networks, the greater the device density, the greater the PIN density, the higher the frequency of the signal design, should try to use multi-layer special laminated structure.
5， electroplated nickel gold / gold finger
Electroplated nickel gold, refers to the electroplating of gold particles attached to the PCB board, because of the strong adhesion, known as hard gold; use of this process, can greatly increase the hardness and wear resistance of the PCB, effectively prevent the spreading of copper to other metals, and adapt to the requirements of soldering and pressing. The plating is uniform， low void ratio, low stress, and good ductility.
Chemical nickel palladium gold, is in the PCB prototyping, using chemical methods immersion a layer of nickel and palladium on the surface of copper. Palladium and gold sink, is a non-selective surface processing. It is through 10 nm thick gold plating layer and 50 nm thick palladium plating layer, so that the PCB surface can achieve good electrical conductivity, corrosion resistance and anti-friction properties.
PCB production is often encountered in the production of non-circular holes, called shaped holes. Including 8-hole, diamond-shaped holes, square holes, serrated holes, etc., mainly divided into holes with copper (PTH), no copper in the hole (NPTH) two.
8，Control deep slot
With the development of diversification of electronic products, special concave fixed components are gradually used in PCB design, resulting in the control of the depth of the slot.