PCB Fabrication

Tell you in detail the basic principles and important functions of Via holes

by:A-TECH      2021-03-18
How to make a Via hole, after reading this article, I hope it will be helpful to you. Here are some basic knowledge questions and answers. Under what circumstances should more ground holes be drilled? There is a saying: drilling more ground holes will destroy the continuity and integrity of the formation. The effect is counterproductive. Answer: First of all, if more holes are punched, the continuity and integrity of the power layer and stratum are caused. This kind of situation should be resolutely avoided. These vias will affect the power integrity, leading to signal integrity problems, which is very harmful. Ground holes usually occur in the following three situations: 1. Ground holes are used for heat dissipation; 2. Ground holes are used to connect the ground layer of a multilayer board; 3. Ground holes are used for high-speed signal transfer. The position of the hole; but all these situations should be carried out under the condition of ensuring the integrity of the power supply. That is to say, as long as the interval of ground holes is well controlled, is it allowed to drill more ground holes? Is it okay to drill ground holes at intervals of one-fifth of the wavelength? If I make more ground holes in order to ensure the ground connection of the multilayer board, although there is no partition, will it affect the integrity of the ground layer and the power layer? Answer: If the copper skin of the power supply layer and the ground layer is not separated, it will not be affected. In current electronic products, the general EMI test range is up to 1Ghz. Then the wavelength of 1Ghz signal is 30cm, and the wavelength of 1Ghz signal 1/4 is 7.5cmu003d2952mil. That is to say, if the spacing of the vias can be less than 2952 mils, it can meet the ground connection and play a good shielding effect. Generally, we recommend to punch ground vias per 1000mil. What is the function and principle of adding a ground via hole near the via hole of the trace? Answer: PCB vias can be classified according to their functions and can be divided into the following categories: 1. Signal vias (via structure requires the least impact on signals) 2. Power and ground vias (via structure requires vias) (Minimum distributed inductance) 3. Heat dissipation vias (the via structure requires the minimum thermal resistance of the vias). The vias mentioned above are grounded vias. The grounding Via hole is added near the via hole of the trace to feed the signal. Provide a shortest return path. Note: The via hole where the signal changes layer is a discontinuity point of impedance, and the signal return path will be disconnected from here. In order to reduce the area surrounded by the signal return path, some ground must be laid around the signal via hole. Vias provide the shortest signal return path and reduce the emi radiation of the signal. This radiation increases significantly with the increase of the signal frequency.
Custom message
Chat Online 编辑模式下无法使用
Chat Online inputting...
Please hold on and we will get back to you soon