2015年3月9日星期一

PCB wiring problems (D)

Processing of large area conductor connection in the leg.
In a large area of grounding (electric), commonly used components of the legs, they are connected to the connection of the leg of dealing with the need to make a comprehensive consideration,in terms of electrical performance, the element of the leg welding plate and copper surface full meet for good, but for the element of the welding assembly there are some bad hidden trouble, such as: (1) welding need high power heater. (2) easy to create virtual solder joints. So both electrical properties and technology needs, make a cross bonding pad, called Thermal isolation (heat shields) commonly known as Thermal bonding pad (Thermal), in this way, can make because of the cross section when welding the possibility of too much heat to generate virtual solder greatly reduced. Multilayer (ground) layer of jump leg at the same treatment

Wiring in the role of network system
In many CAD systems, wiring is determined on the basis of network system. Grid too close, path although increased, but the step is too small, figure the amount of data is too large, it will certainly has higher request to the storage space of the equipment, as well as computer object class has greatly influence the speed of PCB board. And some of the path is invalid, such as being components of bonding pad to take up the legs or occupied by installing hole, the hole, etc. Grid hydrophobic, pathways too little impact on completion rate greatly. So have to a reasonable density of grid system to support the wiring.

Standard components of the distance between two legs is 0.1 inches (2.54 mm), so the basis of grid system is generally 0.1 inches (2.54 mm) or less than 0.1 inch integer number, such as: 0.05 inches, 0.025 inches and 0.02 inches, etc.

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