PCB News - PCB board design: SPS PCB layout rules

SPS PCB Layout Rules
1. Drawing the circuit diagram:
a. Call up the corresponding component symbol, connect and draw; and assign the corresponding PCB board Decal to it;
b. Check whether there is any error in the network; whether the part number is repeated or missed; (Save)
c. Check if there is no error, go to net list to PCB; there should be no error report.

2.PCB drawing:
a. Check whether the package and the network with polar components are correct;
b. 1. Use AUTO-CAD to draw the PCB frame and convert it to *.dxf file to POWER PCB;
§ Note: When switching to POWER PCB, please note that the unit should be metric, if it is imperial, it needs to be converted in AUTO-CAD in advance.
2. After entering the POWER PCB, change its line width to 0.2mm, combine (combin), and store it in the library for use;
c. First call up the PCB file, then call up the PCB outline, set the PCB outline on the twenty-seventh layer, and use the outer frame to draw the PCB outline, mark the size, and then start the layout.
d. PCB parts layout; (only for SPS)
1. Layout according to the principle of first big and then small, vertical left to right, four circuits first;
2. Place the fixed position components first, and then put the INLET, X capacitor, common mode inductor, large capacitor, MOS tube and heat sink, transformer, output rectifier and filter capacitor of the input part;

Note: The choice of heat sink and the choice of transformer will determine the layout of the PCB to a large extent, so the selection of these components should be careful.
Note: For all plug-ins, horizontal components should be used as much as possible. (Because vertical components are not prone to short circuits) The pin holes of horizontal components should be ≧1mm. Vertical components should not be used as much as possible. The deflection appears as a short circuit.
Note: For SMT components, the SMT surface should first consider the direction of the tin furnace, because this determines the direction in which the SMT should be arranged.
Note: When placing the parts on the AI surface, pay attention to whether the "FG" PIN of the INLET will touch other components, such as X capacitors, and the fuse case is metal, so pay attention to the distance from other metal cases, such as electrolytic capacitors, High-voltage capacitors should be kept as far away from the radiator as possible; so as not to transfer heat to the capacitor and reduce the life of the capacitor;
When placing a vertical 2W resistor, peripheral components should be considered, and it is best to omit things such as conduits;
In terms of bridge stack, if space is available, it is best to use four diodes instead of bridge stack, yes;
When designing the radiator, a slightly larger radiator must be designed with more than two PIN pins; when placing the MOS tube, pay attention to the shortest connection between its "D" pole and the transformer; there are also "G", "S" Route, whether it is easy to go;
The PWM control part, this part should be arranged neatly, the IC PWM output line should be as short as possible, and this part should be as far away as possible from the AC input part; if there is space, the diode and the voltage regulator tube should be plugged in as much as possible, which can be Cost Down
With PFC, the PFC IC control part should be separated from the PWM IC control part, especially the respective GND should be separated to the common pin of the high-voltage capacitor. The PFC signal line should not be too thick.
SMT capacitors, especially high-voltage SMT capacitors, should use plug-ins as much as possible, which can be Cost Down; SMT components should be farther away from the AI component pads; in case of high-current traces, they should be necked-down traces;
The transformer is generally placed close to the MOT tube and the secondary components, and a distance of more than 3mm should be maintained. Pay special attention to the transformer without piping, which needs to be led out with three-layer insulated wire, and the transformer's wire package and iron core are regarded as the primary For components, special attention should be paid to the distance between the secondary components and the distance between them, and a distance of more than 4MM should be ensured. If possible, the PIN of the transformer should be retained as much as possible, so that the bulky transformer can be made stronger;
The TO-220 packaged rectifier tube should pay attention to the distance between the output filter capacitor and the output filter capacitor.The output capacitors should be arranged in order and easy to route.
When placing the parts to the side, keep a distance of at least 0.5~1.0mm from the edge, so as not to interfere with each other when connecting the pieces;
The distance between the output element and the SR, understand the size of the SR and the thickness of the line; make it sparse but not sparse, dense but not messy, and look compact and tidy;
When starting the wiring, set the trace width to 0.3mm and the spacing 0.3mm. This trace is mainly to lay the foundation for the subsequent copper paving.

The above is the introduction in the SPS PCB Layout rules. Ipcb is also provided to PCB manufacturers and PCB manufacturing technology.