Greetings all

I've a report regarding PCB manufacturing where i need to compare and contrast TH PCB to SMT PCB.

Assuming i need to create a 1 Layer Double side PCB, I understand for Through-Hole components the
board needs to be drilled and since it's a single layer board i can connect components on the top layer
easily with the bottom layer.

In the case of an SMT PCB, where the board doesn't need to be drilled and components can be mounted
on surface pads, how would smt components on the top layer connect to the bottom layer since SMT PCB's
don't need to be drilled?

 

Multi-layered PCBs are drilled to install vias between layers, regardless if SMT or thru-hole.

 

Who says that SMT PCBs don't need to be drilled? If you want continuity between traces on the top and on the bottom, you better be drillin' (and platin').

 

Who says that SMT PCBs don't need to be drilled? If you want continuity between traces on the top and on the bottom, you better be drillin' (and platin').

Ok makes sense, seems i've misinterpreted "no drilling required for the actually components on the board" but drilling is required for the traces and vias

 

yep.. The SMT components themselves do not need through holes like TH components do for attachment..
But if you have a multi-layer board and you need to connect traces from one side to the other then "vias" are drilled/plated holes that accomplish that need.

 

Ok makes sense, seems i've misinterpreted "no drilling required for the actually components on the board" but drilling is required for the traces and vias

My personal observation is that SMT boards have more vias than through-hole boards. This is because there are no "free" vias where a component lead goes through the board.

 

On very very tight SMT boards you will probably want to stack parts over each other front to back to make some room for the vias. I had this situation a few times.