PCB layout

Printed circuit board design process includes schematic design, electronic components database login, design preparation, block division, Electronic Components configuration, configuration confirmation, cabling and final Inspection. During the process, no matter in which process the problem is found, it must be returned to the previous process, for re-confirmation or Correction.

PCB layout rules: in general, All components should be placed on the same side of the circuit board, only the top-level components are too dense, can be some of the height of the limited and low heat, such as SMD resistors, chip capacitors, SMD IC, etc. on the lower layer. In the premise of guaranteeing the electrical performance, the components should be placed on the grid and parallel or vertical arrangement, in order to tidy, beautiful, in general, the elements are not allowed to overlap; the components are arranged in a compact, uniform distribution of components throughout the Layout. The minimum spacing between the different components of the circuit board and the adjacent pad graphics should be above 1MM. From the board edge is generally not less than 2MM. the best shape of the board is rectangular, and the aspect ratio is 3:2 or 4:3. when the board is larger than 200MM by 150MM, consider the mechanical strength that the board can withstand.

In the PCB layout design to analyze the circuit board unit, according to the function of the layout design, the circuit of all components of the layout, to conform to the following principles: according to the circuit flow arrangement of the various functional circuit unit position, so that the layout of the signal flow, and keep the signal as consistent as possible [1]. Focus on the core components of each functional unit and surround him with the Layout. Components should be evenly, integrally, and compactly arranged on the PCB, minimizing and shortening the leads and connections between the Components. The circuit that works at high frequency should consider the distribution parameters between Components. The general circuit should be as far as possible to make components parallel arrangement, so not only beautiful, and easy to install drought, easy to batch Production.

In the PCB, the special components refers to the high-frequency part of the key components, the core components of the circuit, vulnerable components, with high-pressure components, large heating components, as well as some of the Opposite-sex components, the location of these special components need careful analysis, to do with the layout of the circuit function requirements and production Requirements. Improper placement they may produce circuit compatibility problems, signal integrity problems, resulting in PCB design Failures.

How do you first consider the size of the PCB when placing special components in your layout? When the PCB size is too large, the printing line is long, the impedance increases, the anti-dryness ability drops, and the cost increases; over an hour, the heat dissipation is not good, and the adjacent lines are susceptible to interference. After determining the dimensions of the PCB, the positioning of the special components is Determined. Finally, according to the function unit, all the components of the circuit are laid out. The location of special components in the PCB layout generally follows these guidelines: as far as possible to shorten the connection between High-frequency components, and try to reduce their distribution parameters and electromagnetic interference between each other. The vulnerable components cannot be too close to each other, and the inputs and outputs should be kept as far away from each other. Some components or wires may have a higher potential difference, should increase their distance, so as not to cause an unexpected short-circuit discharge. High-voltage components should be placed as far as possible in the hand to reach the Place. Components weighing more than 15G can be fixed with brackets and Welded. Those heavy and hot components, should not be placed on the circuit board, should be placed on the bottom slab of the host box, and consider the thermal problem. Heat-sensitive components should be away from the heating components. The layout of adjustable components, such as potentiometers, adjustable inductors, variable capacitors, microswitch, etc., should consider the structural requirements of the whole block wrench, some frequently used switches, in the case of structure permitting, should be placed in the hand easily accessible to the Place. The components of the layout should be balanced and dense, not top-heavy.

The success of a product, one is to pay attention to the intrinsic quality. But to take into account the overall aesthetic, both are more perfect wrench, to become a successful product.