EDA > General PCB/EDA/CAD Discussions

Is It OK for Upside Down PCB/Circuit?

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Mechatrommer:
currently i'm placing parts on pcb software, and i'm running out of space from specification. so i think i have to split the parts, some on the bottom and some on above. parts on the above is directly interfacing to the user, pots and switches, and all of them are through hole. for the smd parts, i think i cannot split sides since to make reflow or such (diy and soldering) process later to become easier. so they all have to go to the bottom since i cannot put UI parts on the bottom. so most functionality (mcu, radio, amplifier) will be at the bottom, facing the plastic housing below, when assembled, we will see the large ground plane, with other UI parts on the top, hence "upside down pcb". my concern is, the circuit is detecting EMF pulse (with varying magnitude, max recorded around 30Vpp) from below, may it interfere with circuit functionality? will it corrupt/degrade mcu signal, radio signal and amplifier? if so, how do i overcome this? will just placing an aluminium foil in the housing (below) can avoid this emf interference? is this a common or bad practice? the space (housing) constraint is around 6 x 5 x 1.5 cm as pictured (with its pcb inside) below. hope to get some advice.

Kiriakos-GR:
Shielding with out earth ground it works as antenna.

I can not imagine if you are talking for a portable device or bench type?
Even so to avoid interference you can use coaxial cables and feed thru capacitors. 

Mechatrommer:
its not fun at all! err, its not you kiri my friend. i'm talking about routing that pcb. i have to further split the smd parts on both side, so now they mixed up i dont know how to reflow later. currently reading pcb tutorial rev a 29th june 2004, intro section. i have to agree with the author.
--- Quote ---But for many others the process of designing and laying out a PCB can be a very daunting task
--- End quote ---
and thats me even with this simple pcb.

Mechatrommer:
printing...

IanB:

--- Quote from: Mechatrommer on August 27, 2011, 07:11:33 pm --- i have to further split the smd parts on both side, so now they mixed up i dont know how to reflow later
--- End quote ---
I think you put all the small parts on the underside and reflow that, then you flip the board over and hand solder the bigger parts on the other side, then lastly you hand solder any through hole parts. So in your layout you would try to put the big SMT parts and the through hole parts on the opposite side from the smaller SMT parts.

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