Homebrew PCBs

--- In Homebrew_PCBs@yahoogroups.com, "eeks123" <eeks123@...> wrote:
>
> 
> > Tacky enough that I have populated boards on both sides at the 
same
> > time then stuck in the oven. The parts that went on the bottom 
side
> > were smaller items like 0402 chip capacitors, but they did not go
> > anywhere.
> > 
> > Of course if you do that you will need to add feet to the board 
so it
> > is not resting on the bottom.
> >
> 
> 
> amazing! when solderpaste gets liquid components should drop.. 
that's
> a question i was making myself, is it possible to populate 
components
> on both sides when reflow-soldering? i thought you had to hand-
solder
> components on the second side, if not, bad things would happen..
>

Hi Eeks,
Yes! The smaller chip components will not fall off - surface tension 
holds them pretty tight. Even if you give the board a little jolt 
while the solder is molten, they will generally still not fall off.

You can even put larger components on the bottom of the board, such 
as quad flat packs, SOICs, SOTs, SMT electrolytic or tantalum 
capacitors etc. but to do that you need to put a tiny little dot of 
glue underneath the component before you place it.

It is a bit dicey doing this by hand though, because when you place 
the component it needs to be lined up perfectly - you can't use the 
surface tension to help you with pulling the component into alignment 
in this case.

I've done the glue dot method at a factory before. We made a stencil 
just for applying the glue. Then the board went into an automatic 
pick and place machine to place the components on top of the glue 
dots.

Anthony Burch http://www.SuperSolderingSecrets.com