High Current Pulse EM Coupling between Ground Planes

Thread Starter

ThermalEngineer

Joined Mar 23, 2020
1
Hi,

I am new to the PCB design game and I have a somewhat general question. If you have a multi-layer board as follows:

Layer 1: Misc
Layer 2: Component A Power/signal
Layer 3: Component A RTN Ground Plane
Layer 4: Sensor Power RTN
Layer 5: Sensor signals/Sensor power
Layers 6-8: Misc

If I am expecting a 5A (increase with respect to DC operation) transient pulse with a rise time of 100 ns to 1 microsecond in Layer 2, can the return current in layer 3 electromagnetically couple on to my sensor ground (layer 4) and thereby, induce ground noise? If so, aside from moving the sensor planes to different layers, are there other ways to mitigate this issue? Thanks in advance for any information or help. If chatting is something that would be better to help answer this question, I am most definitely open to chat with anyone who graciously offers a few minutes of their time!
 

Janis59

Joined Aug 21, 2017
1,178
5A / 0.1E-6 sec*10E-9 H/cm=500E-3=0,5 V/cm induced interference Happily it isn’t deadly much.
Yet the sore news are that responsible for speading it takes not an E field what is easy to ecranate, but H field what is much harder to kill. With idea that You shall not use any mju-metall because of price, solution may be the ferrite or the sandwich of regularly punched mild steel plates sequenced by aluminium platelets insulated both sides by som plastic film. If the punche-holes are about 1 mm or less like here https://images-na.ssl-images-amazon.com/images/I/61DWVTCN7IL._AC_SX466_.jpg (I am as much as possible using the TV kinescope mask screen) then the field ecranation effect is quite impressive. Firstly, every hole makes a nude poles into it inner perimeter, therefore each plate not forms clear concentration of field in own boarder (ends), but "suck-in" the field rather uniformly. Second, thoses multitude of small poles instead of one large serts the force according own distance, thus much nearer than non-punched. And aluminuim reflects, however mild but reflects, part of the field back. Those insulator must preserve the right distance let reflection happens in realm of weak fields not a strong fields. For example, if DC magnet have about 60 kilogram force in straight contact, then five-layer discussed structure makes the other magnet other side of this pie feels less than 10 miligrams force measured.
 
Top