Decryption PROTEL DXP software PCB design skills

- Jul 27, 2017-

Protel DXP is the first board design system to integrate all design tools into one. Electronic designers can plan their products from the initial project module to the final production data. Protel DXP runs on the optimized design browser platform, and has all the advanced design features of today, and can handle a variety of complex PCB design processes. As a new circuit design software, Protel DXP has added many new functions on the basis of the previous version. New customizable design environment features include dual display support, fixed, floating and pop-up panels, powerful filtering and object positioning capabilities, and enhanced user interfaces. Through the design of input simulation, PCB drawing, editing, topology automatic routing, signal integrity analysis and design output, Protel DXP provides a comprehensive design solution.

PCB circuit board design principles include: circuit board selection, circuit board size, component layout, wiring, pad, filling, cross wiring, etc..

Flame retardant circuit boards are also required for flame-retardant electronic devices. These boards are laminated with flame retardant resin. The thickness of the circuit board shall be determined according to the function of the circuit board, the weight of the components to be installed, the specifications of the circuit board socket, the size of the circuit board and the mechanical load to be taken.

Considering the cost, the length of copper film and the noise resistance, the smaller the size of the circuit board, the better the plate size is, the poor heat dissipation and the adjacent wires are likely to cause interference. The cost of the circuit board is related to the area of the circuit board. The larger the area is, the higher the cost is. When designing a circuit board with a shell, the size of the circuit board is limited by the size of the case shell, and the size of the cabinet must be determined before determining the size of the circuit board. Otherwise, the size of the circuit board can not be determined.

Although Protel DXP can automatically layout, but in fact, the layout of the circuit board is almost complete by hand.

The following rules are generally followed when the layout is to be carried out:

The layout of special components is considered in the following aspects:

1) high frequency components: the shorter the connection between the high-frequency components, the better to reduce the distribution parameters of the line and the electromagnetic interference between each other, and the components that are susceptible to interference can not be too close. The distance between components that belong to the input and subordinate to the output should be as large as possible.

2) a component with high potential difference: it should increase the distance between the component with high potential difference and the connection so as to avoid accidental short circuit damage to the component. In order to avoid the phenomenon of creepage, it is generally required that the distance between the 2000V potential difference and the copper film line should be greater than 2mm. If the potential difference is higher, the distance should also be increased. Devices with high voltage should be located where the hands are hard to touch during debugging.

3) components with too heavy weight: such components should be fixed with brackets, but for large, heavy and heat generating components, it should not be installed on the circuit board.

4) heating and heat sensitive components: note that heating elements should be away from thermal components.

5) can be adjusted for components: potentiometer, adjustable inductor, variable capacitor, micro switch adjustable element layout should consider the requirements of the whole structure, if the machine is easy to adjust regulation, should be placed on the circuit board, if the machine adjust its position relative to the position should be with the adjusting knob at on the case panel.

According to circuit function layout

If there is no special requirement, the components can be arranged as far as possible according to the arrangement of the components of the schematic diagram. The signals are input from the left and output from the right, and input from above and output from below. According to the circuit process, the location of each functional circuit unit is arranged to make the signal flow more smoothly and keep the same direction. With each function circuit as the core, the layout of the core circuit is carried out, and the component arrangement should be uniform, neat and compact. The principle is to reduce and shorten the lead and connection between the components. The digital circuit part should be separated from the analog circuit.

The distance of the component from the edge of the circuit board

All the components are within plate edge should be placed in the 3mm position, or at least from the edge of the circuit board distance equal to the plate thickness, which is due to pipeline plug and wave soldering in mass production, to provide a guide groove, but also prevent the contour edge of the circuit board caused by damage caused by copper film line breaks lead to waste. If there are too many components on the circuit board and must not exceed 3mm, the 3mm auxiliary edge can be added to the edge of the circuit board, and the V slot on the auxiliary edge is broken by hand at the time of production.

Sequence of element placement

First, place fixed position components that are closely aligned with the structure, such as power outlets, lights, switches, and plug ins. Placing special components, such as heating elements, transformers, integrated circuits, etc.. Finally, put small components, such as resistors, capacitors, diodes, etc..

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