I bought a Hot Air + Solder Station from Ebay for $100 shipped a while
ago. Search "852D solder*" and you will find it.
This device is amazingly good quality for the price. I think this
would probably cost $1000+ if it were made in the US. I set the hot
air at 300C and air setting 2 and I assemble every component in a few
seconds. You can set the soldering iron temperature at 250C and it
will reach that level in a few seconds also.
I've always subcontracted out assembly work but this device makes it
easy and economical to assemble and rework everything SMD yourself
quickly.
Previously, I've been experimenting with home assembly methods. The
best by far I've found has been:
1) Zeph paste in a syringe:
http://www.zeph. com/zephpaste. htm
2) hot air gun -> $100 from ebay
3) cheap hot plate -> $20 from walmart
4) solder flux
I read a lot of tutorials and thought assembly with a stencil was
crucial but actually it's a lot more hassle than it's worth because
you need to clean the stencil and work area.
Now my procedure is:
1) if I have a stencil, apply solder paste with the syringe, wipe with
razor blade -> application with syringe saves a lot of paste even with
a stencil
2) hit every pad with the hot air gun in my left hand to reflow, push
components around with a dental pick in my right hand if I need to
If I need to remove a device, apply some flux all over component, heat
with hot air and push components until it moves then clean up with
isopropyl alcohol.
Previously I used a hot plate but this had several disadvantages
namely it took forever to heat up/cool down and it was difficult to
work with. If you touch it you will burn yourself and if you get
close you to push around small components, you will sweat profusely.
Also if I wasn't careful sometimes I would burn the board and it was
difficult to remove the board without disturbing the components as the
hot plate doesn't cool down fast enough.
With the hot air gun, it's way better. It takes me maybe 10 minutes
for prototype boards. I understand if you are assembling a whole
batch for production but I would still outsource it at that point.
This is the best $100 I spent in a long time.
As a side note, I'm surprised how cheap volume assemble costs. Guys
in Thailand will assemble your components by hand (SMD and through
hole) for $3-8 a board with no minimum.
)