After making this PCB, I learnt the importance of ground plane. Besides ground plane, there is considerable amount of theory behind PCB designing which can provide immunity against ESD, surge, EMI, RFI etc.
After reading some articles and following the suggestions on my previous post, I am trying to make another PCB.
I haven't routed whole board yet because I am not very sure about the robustness of this layout against EMI, RFI, ESD etc. Since this takes experience, I need suggestions from you.
Here is what I am planning to do next:
1) Route most of the PCB on top layer so that I can provide a huge GND pour on the bottom layer in DC zone. (No GND pour in ac zone)
2) Route the remaining board, making sure that decoupling capacitors are as close to micro-controller as possible.
3) Use smd caps and resistors so that I can provide a bigger and continuous ground plane.
4) Keep current loops smaller so as to reduce internal EMI development.
5) Provide ferrite bead at incoming ac power lines to suppress sparks.
Besides this, what other improvements do you suggest for increased stability of this circuit? Any constructive suggestions from your side will be very appreciable.