One, the formation that slot opens in PCB design process

 

The formation that slot opens in PCB design process includes:

 

Break up a trough that cause to power source or ground level; When a variety of different power source or ground should existing on PCB board, it is network of power source of avery kind of and ground network impossibly to allocate a complete plane commonly, commonly used practice is in one or more plane aspirant travel power source is broken up or the ground is broken up. On same plane different break up between formed a chamfer.

 

Via is too concentrated form groove (via includes solder dish had mixed aperture) ; Via crosses layer or power source layer and when doing not have electric join to it, need is all round via so that undertake electric segregation,take a few spaces; But when the distance between via leans too nearly, segregation annulus rises with respect to meeting jackknife, form groove.

 

2, open the groovy influence to function of PCB edition EMC

 

Open groove to be opposite the EMC function of PCB board can cause certain effect, this kind of influence may be inactive, also may be active. Above all the face electricity that we need to understand high speed signal and low speed signal distributings. Below the circumstance of low speed, the method of lowest of voltaic edge resistor flows. Issueing what plan institute shows is low speed electric current from A flows to B, its circumfluence signal returns the state that the source carries from ground level. Right now, face electric current distributings wider.

 

 

Below high-speed circumstance, the action of the inductance on signal circumfluence method will exceed the action of resistor. Signal of high speed circumfluence flows the method of edge impedance lowest. Right now, of face electric current distributing very narrow, circumfluence signal is in into bunchy concentration the lower part of line.

 

 

Should put when antipathic circuit on PCB board, need undertakes “ distributes land the processing of ” , mix according to different power source voltage, number and imitate signal, high speed namely big electric current and signal of low speed signal, small electric current will set ground level respectively. Of the high speed signal that the face gave out once upon a time and circumfluence of low speed signal it is OK to distributing easily understanding distributes land the overlay of the circumfluence signal that can prevent antipathic circuit, prevent in all coupling of ground wire impedance.

 

But no matter high speed signal or low speed signal, span when line the when opening slot metropolis on power source plane or ground level brings a lot of serious problems, include:

 

Increase acreage of voltaic annulus road, increased annulus road inductance, make the weaveform of output allows easy oscillation;

 

Strict to need impedance control, press banding the high speed line that line model takes a line, because go up,still meet plane or a chamfer of next plane or fluctuation plane destroy banding line model, those who cause impedance is discontinuous, pose serious signal integrality problem;

 

The radiate that increases to the space blasts off, suffer the interference of dimensional magnetic field easily at the same time;

 

On annulus road inductance high frequency pressure fall form in all modular radiate source, cable is received to arise outside be being passed in all modular radiate;

 

Increase with board on the possibility that other circuit produces high frequency signal to string together faze (following graphs) .

 

 

3, PCB design runs from opposite directions groovy processing

 

Run from opposite directions groovy processing should follow the following principle:

 

Need line of firm impedance pilot high speed, its trajectory is forbidden cross break up a line, avoid to cause impedance discontinuous, pose serious signal integrality problem;

 

Should put when antipathic circuit on PCB board, should undertake the processing that distribute land, but distribute land to should not create high speed line cross break up a line, also do not want those who create low speed line to cross as far as possible break up a line;

 

Should cross groove to go when the line is inevitable, should undertake the bridge is received;

 

 

Receive plug-in unit (external) should not place lie between in layer meet on, if bigger voltage exists between the A dot on layer and B dot,pursue medium, cable is received to arise outside be being passed likely in all modular radiate;

 

 

High density receives plug-in unit when undertaking PCB is designed, unless have special demand, should make sure earth mat sth resembling a net surrounds commonly each cite a base, when also can undertaking the foot discharges cloth bringing, even ground arranges earth mat sth resembling a net, those who assure ground level is successional, prevent groovy generation;