Abstract: In high-speed PCB design, through hole design is an important factor, it is composed of hole, the pad around the hole and POWER layer isolation area, usually divided into blind hole, buried hole and through hole three types. Through the analysis of parasitic capacitance and parasitic inductance in PCB design, some points for attention in high-speed PCB design are summarized.

Key words: through hole; Parasitic capacitance; Parasitic inductance; Non-penetrating hole technology

The high-speed PCB design in communication, computer, image processing applications, all high-tech value-added electronic product design in the pursuit of low power consumption, low electromagnetic radiation, high reliability, miniaturization, light-duty etc, in order to achieve these goals, in high-speed PCB design, through hole design is an important factor.

Through hole is an important factor in multi-layer PCB design, a through hole is mainly composed of three parts, one is the hole; The second is the pad area around the hole; Third, the isolation area of POWER layer. The process of the hole is to plating a layer of metal on the cylindrical surface of the hole wall by means of chemical deposition to connect the copper foil that needs to be connected in the middle layer. The upper and lower sides of the hole are made into a common shape of the pad, which can be directly connected with the upper and lower sides of the line, or not connected. Through holes can be used for electrical connection, fixation or positioning of devices.

High-speed PCB through hole design

Through holes are generally divided into three categories: blind hole, buried hole and through hole.

Blind hole: a hole located on the top and bottom surfaces of a printed circuit board with a certain depth for connecting the surface circuit to the inner circuit below. The depth of the hole usually does not exceed a certain ratio of the aperture.

Buried hole: a connection hole in the inner layer of the printed circuit board that does not extend to the surface of the printed circuit board.

Blind hole and buried hole two types of holes are located in the inner layer of the circuit board, laminating using through hole molding process to complete, in the formation process may also overlap several inner layers.

Through-holes that run through the entire circuit board and can be used for internal interconnections or as mounting and locating holes for components. Because the through hole in the process is easier to achieve, the cost is lower, so the general printed circuit board are used.