PCB Multilayer Board High Density
PCB tracking process requirements
Generally, the signal line width is 0.3mm(12mil), and the power line width is 0.77mm(30mil) or 1.27mm(50mil).The distance between track and track,track and the solder pad should be greater than or equal to 0.33mm(13mil). In practical applications, the distance should be increased when conditions permit.
When the tracking density is high, it can be considered (but not recommended) to use IC foot to walk two tracks, the width of the line is 0.254mm(10mil), the track spacing is not less than 0.254mm(10mil).
The basic requirements of PAD and VIA are: the PAD diameter should be 0.6mm greater than that of hole; for example, universal pin resistance, capacitance and integrated circuit, etc. use pad/hole size 1.6mm/0.8mm, socket, pin and diode 1N4007, etc. use 1.8mm/1.0mm.In practical application,the actual components size should be determined according to actual size, if OK can increase the size of the welding pad appropriately;
The mounting hole of components designed on PCB board should be about 0.2~0.4mm larger than the actual size of component pins.
Generally via diameter is 1.27 mm/0.7 mm;
When the lining density is high, the size of through-hole can be appropriately reduced, but not too small, 1.0mm/0.6mm can be considered.
(4).Requirements for spacing of welding pad, track and VIA
PAD and VIA: greater than or equal to 0.3mm
PAD and PAD: greater than or equal to 0.3mm
PAD and TRACK: greater than or equal to 0.3mm
TRACK and TRACK: no less than 0.3mm(12mil)
When the density is high:
PAD and VIA: greater than or equal to 0.254mm(10mil)
PAD and PAD: greater than or equal to 0.254mm(10mil)
PAD and TRACK: greater than or equal to 0.254mm(10mil)
TRACK and TRACK: no less than 0.254mm(10mil)
Tracking optimization and screen printing.
"there is no best, only better"! No matter how hard you try to design, after you finish painting, you will still feel that there are many places that can be modified. General design experience is: optimizing tracking time is twice than the first time. After feel no need to modify, it's time to laid copper (Place-> polygon Plane). Copper is generally laid on the ground line (pay attention to the separation of analog ground and digital ground), multi-layer pcb may also need to lay power. For screen printing, pay attention to not be blocked by the device or be removed by the hole and welding pad.At the same time, when design face up to component surface, the underlying legend should do mirror processing, so as not to confuse the level.
Network and DRC check and structure check
Firstly, on the premise of making sure that the circuit schematic diagram design is correct, the generated PCB network file and schematic diagram network file should be netchecked for the physical connection relationship, and the design should be revised in time according to the output file results to ensure the correctness of tracking connection relationship.
After the network check is passed correctly, DRC check for the PCB design, and correct the design in time according to the output file results, so as to ensure the electrical performance of PCB tracking. At last, it is necessary to further check and confirm PCB mechanical installation structure.
PCB making. Before doing it, it is better to have a review process.