Circuit boards, known as printed circuit boards, high-tech signal communication between the bridge, which connects the switch with the mechanical industrial control board, in the circuit board production process, PCB circuit board manufacturers will always be in the industrial control board or RF boards around the circle of holes and copper bands, and even some RF boards will be in the board around the edges of the metallization of the edges, a lot of small partners do not understand why we have to do, is it the engineer in the Show technology, do useless work?
In fact, it is not Oh, this is a natural purpose. Nowadays, with the improvement of the system rate, not only is the timing of high-speed signals, signal integrity issues are prominent, and at the same time due to the system of high-speed digital signals generated by electromagnetic interference and power integrity of the EMC problem is also very prominent. High-speed digital signals generated by electromagnetic interference will not only cause serious interferences within the system, reducing the system's immunity to interference, but also produce strong electromagnetic radiation to the outside space, causing the system's electromagnetic radiation emission seriously exceeds the EMC standard, so that the circuit board manufacturer's products can not be certified by the EMC standard. Multi-layer PCB board edge radiation is a relatively common source of electromagnetic radiation.
Edge radiation occurs when unintended currents reach the edges of the ground and power layers and is characterized by: Ground and power noise from inadequate power bypass. Cylindrical radiated magnetic fields generated by inductive vias, which radiate between board layers and eventually converge at the board edge. Ribbon line return currents carrying high frequency signals too close to the board edge. To prevent this, a ring of grounded vias is punched around the PCB at 1/20 wavelength hole spacing to form a grounded vias shield that prevents the TME wave from radiating externally.
For microwave circuit boards, its wavelength further reduced, and because the PCB production process now, the spacing between the holes and holes can not be made very small, at this point has been 1/20 wavelength spacing around the PCB to play shielding over the holes for the microwave board has been less obvious, then you need to use the PCB version of the metallized edge wrapping process, the entire board edge with metal surrounded by microwave signals can not radiate out of the PCB. PCB board edge radiation out, of course, the use of board edge metallization process, will also lead to PCB manufacturing costs increased by many.
For RF microwave boards, some sensitive circuits, as well as circuits with a strong source of radiation can be designed to weld a shielding cavity on the PCB, PCB circuit boards in the design of the addition of "shielding wall over the holes", that is, in the PCB and shielding the cavity wall immediately adjacent to the part of the addition of grounding over the hole. This forms a relatively isolated area. After confirming that there is no error, to be sent to the multilayer circuit board manufacturers to evaluate the production!
Above is about the PCB circuit board around the circle of holes or the use of metal cladding, Shenzhen Jiubao Technology Co., Ltd. specializes in bulk manufacturing production of circuit boards, products mainly include multilayer boards, special boards. Support a variety of processes and production, in terms of technology with 15 years of experience team.