What I want to share with you today is information related to EDA and IC design. Next, I will analyze the seven practical steps of PCB circuit board design and introduce the aspects of circuit board, circuit board and pcb.
(1) Circuit schematic design: The circuit schematic design is mainly based on the Advanced Schematic system of PROTEL099 to draw a circuit schematic. In this process, we need to fully utilize the various schematic drawing tools and editing functions provided by PROTEL99 to achieve our goal of obtaining a correct and exquisite circuit schematic.
(2) Generating a network table: A network table is a bridge between circuit schematic design (SCH) and printed circuit board design (PCB), and it is the soul of circuit board automation. The network table can be obtained from the circuit schematic or extracted from the printed circuit board.
(3) Printed Circuit Board Design: The design of printed circuit boards is mainly aimed at another important part of the PCB in PROTEL99. In this process, we use the powerful functions provided by PROTEL99 to achieve the layout design of the circuit board and complete high difficulty tasks.
But in practice, the specific steps are mainly divided into the following steps:
1、 Preliminary work for circuit board design: 1. Use schematic design tools to draw schematic diagrams and generate corresponding network tables. Of course, in some special cases, such as when the circuit board is relatively simple and there is already a network table, it is also possible to enter the PCB design system directly without designing the schematic. In the PCB design system, parts can be directly packaged and a network table can be manually generated. 2. Manually modify the network table to define some components with fixed pins or pads that are not on the schematic diagram to the connected network, and those without any physical connections can be defined to ground or protective ground. Change the pin names of some devices that do not match the schematic and PCB packaging library to match those in the PCB packaging library, especially for diodes and transistors.
2、 Draw your own packaging library for non-standard devices. It is recommended to include all the devices you have drawn in a dedicated PCB library design file that you have created.
3、 Set up the PCB design environment and draw the frame of the printed circuit, including the hollow in the middle.
1. The first step after entering the PCB system is to set up the PCB design environment, including setting grid size and type, cursor type, layout parameters, wiring parameters, and so on. Most parameters can be set with system default values, and after being set, they are in line with personal habits and do not need to be modified in the future.
2. Planning the circuit board mainly involves determining the border of the circuit board, including the size of the circuit board, and so on. Place appropriately sized solder pads where fixed holes need to be placed. For 3mm screws, pads with 6.5~8mm outer diameter and 3.2~3.5mm inner diameter can be used. For standard boards, they can be transferred from other boards or PCWizard. Attention - Before drawing the circuit board border, make sure to set the current layer as the KeepOut layer, which prohibits wiring layers.
4、 After opening all the PCB library files to be used, it is a very important step to call in the network table file and modify the part packaging. The network table is the soul of PCB automatic wiring, and is also the interface between schematic design and impression circuit board design. Only after the network table is loaded can the circuit board be wired. In the process of schematic design, ERC inspection will not involve packaging issues of parts. Therefore, during schematic design, the packaging of parts may be forgotten, and when introducing network tables, the packaging of parts can be modified or supplemented according to the design situation. Of course, a network table can be manually generated within the PCB and part packaging can be specified.
5、 The placement of part packaging, also known as part layout, Protel99 can be automatically or manually laid out. If performing automatic layout, run "AutoPlace" under "Tools" and use this command, you need to have enough patience. The key to wiring is layout, and most designers use manual layout. Select a component with the mouse, hold down the left mouse button, drag the component to the destination, release the left mouse button, and fix the component. Protel99 has added some new techniques in terms of layout. New interactive layout options