How to design and process high-speed PCB microvia

- Aug 18, 2018-

How to design and process high-speed PCB microvia

Microvia is used by circuit makers on boards where different properties of the circuit have to be separated, but are best connected without electromagnetic interference.Generally, micro via holes are 0.05mm to 0.20mm in diameter, which are generally divided into three types, namely blind via, bury via and through via.The blind hole is located on the top and bottom surface of the printed circuit board and has a certain depth, which is used for connection between the surface circuit and the inner circuit below. The depth of the hole usually does not exceed a certain ratio (hole size).A buried hole is a hole in the inner layer of a printed circuit board that does not extend to the surface of the circuit board.Both of the above two types of holes are located in the inner layer of the circuit board. Before the lamination, it is completed by the through-hole molding process, and several inner layers may be overlapped in the process of through-hole formation.The third is called a through-hole, which passes through the entire circuit board and can be used for internal interconnection or as a component's adhesive locating hole.

When designing RF circuit boards, the high-power RF amplifier (HPA) and the low-noise amplifier (LNA) should be isolated as much as possible. In simple terms, the high-power RF emission circuit should be kept away from the low-noise receiving circuit.This can easily be done if there is a lot of space on the PCB board.But usually when there are many components, the PCB space becomes very small, so this is very difficult to achieve.You can put them on both sides of the PCB board or have them work interchangeably rather than simultaneously.High-power circuits may sometimes include RF buffers and VCO.

Design partitioning can be divided into physical partitioning and Electrical partitioning.Entity partition mainly involves the layout, orientation and shielding of components.Electrical partitions can continue to be divided into power distribution, RF routing, sensitive circuits and signals, grounding, and so on.

The zero component layout is the key to achieving an excellent RF design. The most effective technique is to fix the zero component on the RF path first and adjust its orientation to minimize the length of the RF path.Keep RF input away from RF output and as far as possible from high power circuits and low noise circuits.Friends with PCB design can add Q to discuss Q800058675 together

The most effective circuit board stack method is to arrange the main grounding under the surface layer of the second layer, and as far as possible to the RF line on the surface.Minimising the through-hole size on the RF path not only reduces path inductance, but also reduces virtual solder spots on the main grounding and reduces the chance of RF energy leakage to other areas within the laminate.

In physical space, linear circuits such as multistage amplifiers are usually sufficient to isolate multiple RF areas from each other, but diplexers, mixers, and intermediate frequency amplifiers always have multiple RF/IF signals interfering with each other, so this effect must be carefully minimized.RF and IF routing should cross as far as possible, and as far as possible between them a piece of ground area.The correct RF path is important for the performance of the entire PCB board, which is why the component layout usually takes most of the time in the PCB design of mobile phones.

On the PCB board of a mobile phone, it is usually possible to put a low-noise amplifier circuit on one side of the PCB board, while a high-power amplifier is placed on the other side and eventually connected to one end of the RF antenna and the other end of the baseband processor by a diplexer on the same side.This requires some skill to ensure that the RF energy is not transmitted through holes, from one side of the plate to the other, and a common technique is to use blind holes on both sides.The adverse effect of the through-hole can be minimized by placing the blind hole in an area where both sides of the PCB are free from RF interference.