The Electrical Rules That Need To Be Noticed In PCB Design And Typesetting

1, processing of power supply and ground wire


Even though the wiring in the entire PCB board is done well, the interference caused by the inconsiderate power and ground wire will make the performance of the product decline, sometimes even affect the success rate of the product. So the wiring of electric and ground wire should be seriously treated, and the noise interference produced by electric and ground wire is reduced to a minimum to ensure the quality of the product.


For every engineer engaged in electronic product design, we know the cause of the noise between the ground wire and the power cord. Now we only need to describe the noise reduction mode: it is known that the coupling capacitance is added between the power supply and the ground wire. Try to widen the power and ground is better than the power supply wire width, line width, the digital circuit PCB available wide wire to form a loop, which constitute a network to use (analog circuit to not used) by a large area of copper layer with the ground, was not the place to use connected and as the ground used in printed circuit board. Or make multi-layer board, power supply, ground wire occupy one layer each.


2, the common ground processing of digital and analog circuits


Many PCB are no longer a single functional circuit (digital or analog), but are composed of digital and analog circuits. Therefore, it is necessary to consider the mutual interference between them, especially the noise interference on the ground line. The high frequency digital circuit, analog circuit is more sensitive to the signal lines, signal lines, high-frequency circuit device simulation as far as sensitive, to the ground, the entire PCB to the outside world only one node, so we must address the problem of total number, die within PCB, but in the internal digital and analog ground are actually separate them between each other, only in the PCB and external connection interface. There is a short connection between the digital and analog, please note that there is only one connection point. It is also not common on the PCB, which is determined by the system design.


3. The signal line is on the electric (ground) layer


In the multilayer wiring printed board, the signal line layer does not end the remaining cloth line is not much, more layers will be wasted will increase some work for the production cost also increases accordingly, in order to solve this contradiction, can be considered in the electrical wiring layer (ground). In the first place, the power layer should be considered, and the next is the formation.  Because it is best to preserve the integrity of the formation.


4. The place where the leg is connected in a large area of conductor


In a large area of grounding, the connection of common components and its connection to the connecting leg need to be considered comprehensively. For electrical performance, the pad of the component legs is well connected with the copper surface, but there are some hidden dangers for the assembly and welding of components, such as:


High power heaters are required for welding.


Easy to cause the weld point. So both the electrical properties and process requirements, made of cruciferous pads, called heat isolation (heat SHIELD) commonly known as thermal pad (THERMAL), it can make the possibility of resulting weld point due to excessive heat in the welding section is greatly reduced.  The handling of the floor legs of the multilayer board is the same.


5. The role of network system in wiring


In many CAD systems, wiring is determined according to the network system. Although the grid density is increasing, the step size is too small, and the data volume of the field is too large. This will inevitably have higher requirements for the storage space of the device, and at the same time, it also has a great influence on the computing speed of the object computer type electronic products. Some of the channels are ineffective, such as the occupancy of the welded plate of the leg of the element, or the occupancy of the installed holes and the fixed holes.


The grid is too sparse, too little pathway has a great influence on the efficiency of the. So there is a clear and reasonable grid system to support the routing. The distance between the two legs of a standard component is 0.1 inches, so the base of the grid system is generally defined as a 0.1 inch or less than 0.1 inch integer.


 

(Source: internal information)