PCB production process

Circuit design skills PCB design process The general basic PCB design process is as follows: preliminary preparation->PCB structural design->PCB layout->wiring->wiring optimization and silk screen->network and DRC inspection and structural inspection->plate making.

First: preliminary preparation.

This includes preparing component libraries and schematics.

"If a worker wants to do his job well, he must first sharpen his tools." To make a good board, in addition to designing the principles well, you must also draw well.

Before designing the PCB, you must first prepare the component library of the schematic SCH and the component library of the PCB.

The component library can use peotel's own library, but it is generally difficult to find a suitable one. It is best to make your own component library based on the standard size data of the selected device.

In principle, make the PCB component library first, and then make the SCH component library.

PCB component library requirements are relatively high, which directly affects the installation of the board; SCH component library requirements are relatively loose, as long as you pay attention to defining the pin attributes and the corresponding relationship with PCB components.

PS: Pay attention to the hidden pins in the standard library.

After that comes the design of the schematic diagram. Once completed, you are ready to start PCB design.

Second: PCB structure design.

In this step, based on the determined circuit board size and various mechanical positioning, the PCB board surface is drawn in the PCB design environment, and the required connectors, buttons/switches, screw holes, assembly holes, etc. are placed according to the positioning requirements.

And fully consider and determine the wiring area and non-wiring area (such as how much area around the screw hole belongs to the non-wiring area).

Third: PCB layout.

To put it simply, layout means placing devices on the board.

At this time, if all the preparations mentioned above are done, you can generate the network list on the schematic diagram (Design->CreateNetlist), and then import the network list on the PCB diagram (Design->LoadNets).

I saw the devices piled up all over the place, and there were flying wires between each pin to indicate connection.

Then the device can be laid out.

The general layout is carried out according to the following principles: ①.

According to the reasonable zoning of electrical performance, it is generally divided into: digital circuit area (that is, fear of interference and interference), analog circuit area (fear of interference), and power drive area (source of interference); ②.

Circuits that complete the same function should be placed as close as possible, and components should be adjusted to ensure the simplest connection; at the same time, the relative positions between functional blocks should be adjusted to ensure the simplest connection between functional blocks; ③.

For components with large mass, the installation location and installation strength should be considered; heating components should be placed separately from temperature-sensitive components, and heat convection measures should be considered if necessary; ④.

Place the I/O driver device as close to the edge of the printed board and the lead-out connector as possible; ⑤.

The clock generator (such as crystal oscillator or clock oscillator) should be as close as possible to the device that uses the clock; ⑥.

A decoupling capacitor needs to be added between the power input pin of each integrated circuit and ground (usually a monolithic capacitor with good high-frequency performance is used); when the circuit board space is dense, a decoupling capacitor can also be added around several integrated circuits.

Tantalum capacitor.

⑦.

A discharge diode (1N4148 is enough) should be added to the relay coil; ⑧.

The layout needs to be balanced, dense and orderly, and cannot be top-heavy or too heavy - special attention needs to be paid. When placing components, the actual size of the components (area and height) and the relative relationship between the components must be considered.

position to ensure the electrical performance of the circuit board and the feasibility and convenience of production and installation. At the same time, on the premise of ensuring that the above principles can be reflected, the placement of the components should be appropriately modified to make them neat and beautiful. For example, if the same components are to be placed

They should be neat and in the same direction, and should not be placed "at random".

This step is related to the overall image of the board and the ease of wiring in the next step, so you need to put a lot of effort into it.

When laying out, you can do preliminary wiring first and give full consideration to areas that you are not sure about.