+86-13725088886  sales@olinktek.com

BLOG

pcb multilayer board manufacturer design over hole considerations

Time:2021-08-23 15:52

The most important design of the production of multilayer PCB circuit board is the design of the hole and line alignment design, on the current PCB multilayer board mostly used in communications, medical and other fields, multilayer board manufacturers to meet the needs of various industries on dense precision multilayer circuit board, hole design is an important link, the hole is usually divided into blind, buried holes, through-hole three categories, in the design of multilayer PCB circuit board process by the parasitic capacitance of the hole and parasitic inductance analysis, summarized on the PCB multilayer board production and processing design over the hole specific matters needing attention which are a few!  
pcb multilayer board
① over-hole parasitic capacitance: PCB over-hole itself has a parasitic capacitance to ground, when the over-hole in the layered isolation hole diameter D2, over-hole pad diameter D1, PCB board thickness away from T, PCB substrate dielectric constant ε, the size of the parasitic capacitance of the over-hole approximated by C = 1.41εTD1/(D2-D1), over-hole parasitic capacitance will cause the main impact on the circuit is to extend the signal The smaller the capacitance value, the smaller the impact, and the larger the capacitance value, the greater the impact. 
 
The parasitic inductance of the over-hole: In addition to the parasitic capacitance itself, there is also a parasitic inductance, multilayer circuit board in high-speed operation, the harm caused by the parasitic inductance of the over-hole is much greater than the impact of the parasitic capacitance, the parasitic series inductance of the over-hole will weaken the role of the bypass capacitor, weakening the filtering utility of the entire power supply system, if: L refers to the over-hole inductance, H refers to the length of the over-hole, D refers to the diameter of the center hole, over-hole parasitic inductance Approximate L=5.08h[ln(4h/d)+1], from the number of formula, the diameter of the hole has a small impact on the inductance, the biggest impact on the inductance is the length of the hole.

document.write ('');