On Dec 7, 2008, at 12:07 PM, Wouter van Ooijen wrote:

>>
> I just got a solder paste stencil, so I tried a PCB using that method.
> Very easy, and a lot quicker. I used a paint stripper. Not ideal, but
> certainly doable. (I will probably either build or buy an oven, or  
> maybe
> a hot-plate.) The flip side has some larger SMD components (SOIC28 and
> some FETs), those were easy too. The main problem is how to use the
> stencil when the bottom side is already populated, so it isn't an even
> surface.
>

When I saw a stencil used, the board (usually several boards prior to  
separating at the scribe line) was placed in a frame, a blob of paste  
was placed over the stencil, and a squeegee was passed several times  
across the stencil.  Following this, the board was placed in a pick  
and place machine, though I imagine parts can be placed by hand.

I have seen in some magazines (Elektor, I believe) where a modified  
toaster oven is used for SMD soldering.  The lower and upper heating  
elements are individually controlled (a PIC-based thermostat  
control).  This apparently allows enough temperature control to solder  
the opposite side of the board without components falling off the top  
side.

It would be interesting to try the toaster oven approach.  As a  
hobbyist, I couldn't afford nor justify any professional grade SMD  
equipment.
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