Hello, I am new to SMT layout. Where I work we are taking everything to SMT
in the future. I have experience with PTH, and I am sure some of that will
carry over, but I need to learn more about SMT layout so that I am prepared
if and when the time comes to go to SMT.
I am doing some SMT layouts in eagle just to get the hang of things. Simple
low frequency analog circuits that do not need more then 2 layers.
My intuition was to have the bottom be a GND pour, and to route most of the
board on the top layer. Run power on the bottom, via up to the power pins.
By PTH habit I have my ICs in line with each other so that power maybe run
to them in straight lines. Decoupling caps near power pins, via down to the
GND pour.
Again, by habit, I have all resistors aligned the same direction. This made
much difference in PTH layout, as it allowed a "tunnel" to run traces
through. With SMT, it does not seem so necessary...
Using smaller traces too, as the pads are smaller. I see that some people
run traces between the pins of a SOIC (typical SMT opa) chip! This seems
hazardous. I guess I need to trust the fabrication process more?
I hope this post is not too much of a ramble. Is there a good resource for
SMT layout guidelines? That might answer some of my questions.
THanx,
Tony