PCB Blog - Common PCB board design knowledge questions and answers

Question 1: what is part packaging and what is the difference between it and parts?

(1) Part packaging refers to the appearance and solder spot position indicated when the actual part is welded to the printed circuit boards.

(2) Part packaging is only part appearance and solder spot position, pure part packaging is only the concept of space, so different parts can share the same part packaging; On the other hand, the same parts can also have different packaging, such as RES2 on behalf of resistance, its packaging form has AXAIL0.4, AXAIL0.3, AXAIL0.6 and so on, so when taking welding parts, we should not only know the name of the part but also know the packaging of the part.

(3) The package of parts can be specified in the design of the circuit diagram, can also be specified in the introduction of the network table. You can specify the Footprint setting in the Part Properties dialog when designing the circuit diagram, or you can specify the part package when importing the network table.

Question 2: What is the difference between wire, fly wire and network?

Wire, also known as copper film wire, wire for short, is used to connect each solder joint, is an important part of the printed circuit boards, printed circuit board design is around how to arrange wire. Another type of wire related to a conductor, often called a flying wire or a predrawn wire. After the introduction of the network table, the system according to the rules generated, used to guide the wiring of a wire. There is an essential difference between flying wire and conducting wire. Flying wire is only a form of connection, it is only the form of the connection between the solder joints, there is no electrical connection significance. The wire is arranged according to the connection relation between solder joints indicated by the flying wire, which is a connection line with the significance of electrical connection. A network is different from a wire, which also includes solder joints, so referring to a network includes not only the wire but also the solder joints connected to the wire.

Question 3: What is the difference between inner layer and middle layer?

Middle layer and inner layer are two confusing concepts. Intermediate layer refers to the intermediate plate layer used for wiring, the layer is distributed in the wire; The inner layer refers to the power supply layer or ground layer, the layer is generally not wired, it is composed of the whole piece of copper film.

Q4: What is an internal network table and an external network table, and what is the difference between them?

Network tables are classified into external network tables and internal network tables. External network table indicates the network table, namely the schematic network table generated by Sch or other schematic design software; Internal network table is based on the imported external network table, after modification, used in the PCB system for wiring. Strictly speaking, these two types of nettables are completely different concepts, but readers need not distinguish them strictly.

Question 5: What does the nettable manager do?

First, the introduction of network table, the introduction of this network table is actually the process of loading the schematic design data into the PRINTED circuit board design system PCB. All data changes in the PCB design system can be accomplished by using Netlist Macro, which is automatically generated by comparing and analyzing network table files with the internal data of the PCB system. Secondly, the network table manager can be used to edit the connection relation between each component of the circuit board directly in the PCB system to form the network table.

Question 6: What is a class and what are the benefits of introducing the concept of a class?

A class is a collection of units with the same meaning. The class definition in PCB is open to users, who can define the meaning and composition of the class by themselves. The introduction of classes in a PCB serves two main purposes:(1) Facilitate wiring F In the circuit board wiring process, some networks need special processing, such as some important data lines in order to avoid the interference of other components on the circuit board, in the wiring often need to increase the safety distance between these data lines and other components. These data lines can be classified into a class, and this class can be added to the rule when setting the automatic wiring safety spacing rule, and the safety spacing can be appropriately increased, so when automatic wiring, the safety spacing of all data lines in this class will be increased; The power supply and ground cable should be bolded to ensure the reliability of the connection. The power supply and ground cable can be grouped into one category. When setting the WidthConstraint rule, you can add this category to the rule and increase the wire width appropriately. Both the power and ground wires in this class will be wider.

(2) easy to manage circuit board components F for a large circuit board, it has a lot of parts package, there are thousands of networks, very messy, the use of class can be very convenient to manage the circuit board. For example, to classify all input networks in the circuit board, when looking for an input network, you only need to look in this input network class. The circuit board can also be classified by the finite voltage resistance, when looking for a voltage limiting resistance, just look in this voltage limiting resistance class.

Q7: How to add additional solder joints to the network?

You can first add the solder joint to the circuit board, and then double click the solder joint, open the solder joint property setting dialog box, in Advaced Net items to select the appropriate network, you can complete the placement of the solder joint.

Question 8: What is the use of inner segmentation?

The inner layer can be used to connect some important circuits, which can improve the anti-interference ability and also play a protective role on important circuits.

Question 9: what effect does copper pack have, what should notice?

The main role of copper coating is to improve the anti-interference ability of the circuit board. If you want to wrap the wire or fill the tear drops on the line, then copper coating should be carried out on PCB board.