Designing/Populating PCB's with SMD components on BOTH sides-How?

[djsb]

I'm a total newbie when it comes to making and populating prototype PCB's with SMD components. One thing I'm wondering about is how to solder SMD components onto a DOUBLE sided PCB? I'm guessing it's fairly easy if using HAND soldering with a soldering iron. What is the technique required if using solder paste and a hot plate or reflow oven? It would make sense to put as many components as possible onto just one side of the PCB. But it would be a shame to not make use of both sides if possible.
I'm primarily interested in a pragmatic way to work with one-off prototype PCB's. However, I need to have in mind how to design a PCB for possible larger volume production. How would a double-sided PCB be populated on a production line? Thanks.

[mariush]

I would guess  a common practice would be to use drops of glue under components, and do wave soldering or spread solder paste using stencil before the parts are glued down and then run the circuit board through an infrared oven or some other way of flowing the solder.

see https://www.nexpcb.com/blog/how-to-use-smt-red-glue

[barshatriplee]

For double-sided PCBs with SMD components, the board will need to go through sequential reflow soldering unless you opt for hand assembly. Reflow soldering will be used on high-volume runs/low-cost prototyping runs, so designers should plan for reflow soldering during assembly.

https://resources.altium.com/p/best-design-practices-double-sided-pcb-soldering-smd-parts

[KaneTW]

I'm a total newbie when it comes to making and populating prototype PCB's with SMD components. One thing I'm wondering about is how to solder SMD components onto a DOUBLE sided PCB? I'm guessing it's fairly easy if using HAND soldering with a soldering iron. What is the technique required if using solder paste and a hot plate or reflow oven? It would make sense to put as many components as possible onto just one side of the PCB. But it would be a shame to not make use of both sides if possible.
I'm primarily interested in a pragmatic way to work with one-off prototype PCB's. However, I need to have in mind how to design a PCB for possible larger volume production. How would a double-sided PCB be populated on a production line? Thanks.

You do not need to do anything. Most parts will be held in place by surface tension (I forgot the weight/solder contact area threshold).

For the parts that don't, you can glue them or use a lower-temp solder paste for the second pass.