PCB版设计主要步骤是什么？

First, the circuit board design work PCB design system

1, the use of schematic design tools to draw schematics, and generate the corresponding network table. Of course, in some special cases, such as the circuit board is relatively simple, there is already a network table and other cases can not be schematic design, direct access to PCB design system, the PCB design system, you can directly access the parts package, Manually generated network table.

2, manually change the network table will be some of the components such as pin fixed on the principle of the map is not defined on the interconnection to the network, there is no physical connection can be defined or protected and so on. Will be some schematic and PCB package library pin name inconsistent with the pin into the same package and PCB library, in particular, two, transistor and so on.

Second, draw your own definition of the non-standard package library

Proposed to put their own devices are placed in a PCB design library created their own dedicated design documents.

Third, set the PCB design system environment and draw the circuit version of the box with the middle of the hollow and so on

1, into the PCB design system PCB system after the first step is to set the PCB design environment, including setting grid size and type, the cursor type, layer parameters, wiring parameters and so on. Most of the parameters can use the system default values, and these parameters are set, in line with personal habits, no need to modify later.

2, planning circuit version, mainly to determine the circuit version of the border, including the circuit version of the size and so on. Place pins of appropriate size where the holes need to be placed. For 3mm screws available 6.5 ~ 8mm OD and 3.2 ~ 3.5mm ID pad for the standard board can be transferred from other boards or PCB izard.

Caution - Be sure to set the current layer as the Keep Out layer before drawing the border of the circuit board, that is, disabling the wiring layer.

Fourth, open all the PCB library files to be used, transferred to the network table file and modify the parts package

This step is a very important step, the network table is the soul of PCB automatic routing, but also the schematic design and the impression of the circuit board design interface, only after the network table is loaded, to the circuit version of the wiring.

During the schematic design, the ERC inspection did not involve the packaging of the part. Therefore, the schematic design, parts package may be forgotten, the introduction of the network table can be modified according to the design situation or supplement parts package.

Of course, you can create network tables manually in the PCB and specify the parts package.

Fifth, the location of the parts package, also known as part layout

Protel99 can be automatic layout, you can also manually layout. If you are auto-layouting, run "Auto Place" under "Tools" and you will need to be patient enough with this command. The key is the layout of the layout, most designers use manual layout form. Use the mouse to select a component, hold down the left mouse button, drag the component to its destination, release the left button, the component fixed. Protel99 added some new layout skills. The new interactive layout options include automatic selection and automatic alignment. With automatic selection, packages of similar packaging can be quickly collected, then rotated, unwrapped and organized into groups to move to the desired location on the board. When the simple layout is complete, use a self-aligning neatly expand or contract a group of similar package components.

Tip - Use Shift X or Y and Ctrl X or Y to expand and contract X, Y directions for the selected component when auto-selected.

Note - Part layout should be considered from the mechanical structure of heat, electromagnetic interference, future wiring convenience and so on. The first thing to do is to arrange the devices that are related to the mechanical size and lock these devices, then the large, central components of the device and circuit, and then the small peripheral components.

Six, according to the situation and then make appropriate adjustments and then lock all the devices

If the board space allows you can put some board on the board similar to the experimental board layout. For large board, should be more in the middle of fixed screw holes. Board heavy devices or larger connectors and other force devices should also be added to the edge of the fixed screw holes, if necessary, put some test pads in place, it is best to add in the schematic. Will be too small pad vias to large, all the fixed screw hole pad network to the ground or protection and so on.

Take a look at the actual effect with VIEW3D function save the disk.

Seven, wiring rules set

Routing rules are the rules for setting the routing (such as the usage level, the width of each group, the spacing of vias, the topology of the routing and some other rules, which can be imported from other boards at Design-Rules Menu and then imported into this board ) This step does not have to be set every time, according to personal habits, set once.