PCB design entry

- Aug 04, 2016-

1) printed circuit board structure in general, printed circuit board structure of single-sided, double-sided and multilayer three. 

(1) is a single-sided single-sided copper-clad one side, the other side there is no copper-clad circuit board, the user can only its copper wiring and left side elements. Single panel because of its low cost, without holes played is widely used. Since the single-panel wiring only on one side were, therefore, its design is often much more difficult than the double-sided or multilayer. 

(2) Double panel Double panel comprises a top layer (TopLayer) and the bottom (BottomLayer) two layers, the top layer is generally the component side, solder layer is generally level, double-sided panels have copper, can be wiring. Double-sided circuit generally higher than the single-sided circuit complexity, but the wiring is easier, is to produce a circuit board ideal choice. (3) MLB MLB is included LP2902N / NOPB plurality of working-level circuit board. In addition to the above-mentioned top, bottom, further comprising an intermediate layer color, internal power or ground layer. With the rapid development of electronic technology, more and more sophisticated electronic products, circuit boards will become increasingly complex, multi-layer circuit board applications are increasingly widespread. Multi-layer circuit board generally refers to three or more circuit boards.

2) End Part packages typically a printed circuit board design, you will get it Making the board unit exclusively of Making the board. After retrieving the prepared circuit board, to welding parts up, then how to ensure consistent weld pin and the printed circuit board access parts of it? We must rely on the part of the package. Part Encapsulation refers to the actual item soldered to the circuit board and solder joint appearance of the designated location. Since the package is only part of the appearance and location of solder joint parts, so pure parts package is only the concept of space, so different parts can be a part share the same packaging; on the other hand, the same species can have different parts of the package, such as RES2 on behalf of the resistance, its package has AXIALO.3, AXIALO.4, AXIALO.6 etc., so when access welding parts, not only to know the name of the part, but also know the parts of the package. Part of the package can be specified in the design of the circuit diagram, you can also specify in the introduction of the network table. 

(1) Part package package classification of parts can be divided into two categories, namely stitch parts packaging and STM (surface mount type) parts package. 

① stitch stitch parts package packaging parts as shown in Figure 7-1. Parts must first pin the parts pin inserted welding joints vias before soldering. Since the stitch part of the package lead solder larvae L throughout the circuit board, so the solder joint properties dialog box, Layer lamellar property must be MultiLayer. 

②STM Part Package STM parts package is limited to the surface of solder plate layer of solder joints Properties dialog box, Layer lamellar property must be a single surface, such as Toplayer or BottomLAyer. STM Part package shown in Figure 7-2. No part of the package number 

(2) Part of the package is generally part type from the ten joints (welding points) + part dimensions. We can package Part Number Part discriminated packaging specifications. As part of this package AXIALO.4 axis represents the distance like, two solder joints is 400mil (equal to about 10mm); DIP16 showing double-pin package parts, two rows of 16 pins; RB.2 /. 4 shows a polar capacitor type parts package, pin distance between 200mil, part diameter of 400mil. Here. 2 and 0.2 represents 200mil (l inch -25.4 mm).

3) copper film conductor copper film conductor traces also known copper film, referred to as conductors for connecting the respective pads, the printed circuit board is the most important part. Prostrate printed wiring board design revolves around how the wires are arranged to carry out. Another related with the wire line, we often referred to the fly line, namely the pre-cable. Fly line is the introduction of the network in the table, the system generated according to the rules for one kind of connection wiring guidelines. Fly line and wires are essentially different, fly line is only a formal connection, it just shows the connection relationship between the various forms solder joints, there is no sense electrical connection. Lead solder is based on the connection relation between the fly line and indicating arrangement is electrically connected with a connection line sense.

4) the role of pads and vias are placed solder joints, connecting wires and component pins. The role of the guide wire connection hole is different board layers, vias there are three kinds, namely, from top to bottom through the guide hole penetrating from the top or from the inner layer to pass through to the underlying inner layer vias and blind hidden between the inner guide hole. Pilot hole from the surface appears to have two dimensions, namely, through-hole diameter and the diameter of the guide hole. Hole wall through holes and vias between the conductor is the same material used for conductors connected to different plies.

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