On Thu, Mar 26, 2009 at 3:06 PM, solarwind <x.solarwind.x@gmail.com> wrote:
> I recently read an article on the Sparkfun website regarding reflow
> soldering for surface mount components that can be done at home on any
> form of hot plate (stove top frying pan, skillet, etc...).
>
> I have several questions regarding this (that were unanswered in the
> article, and for which I was unable to find answers on the Internet).
>
> * I thought heat damages components. I was consistently cautioned not
> to overheat components during hand soldering. If the idea is to heat
> up the solder just enough to melt (and maybe a bit more so as not to
> form a "cold soldered" joint), then wouldn't reflow soldering do the
> same damage to components?
>
> * One of my DIP chips came with a notice saying that it should be
> "cooked" at 125 degrees Celsius prior to reflow soldering. I would
> never reflow solder a DIP chip, but this is interesting. Why do they
> have such requirements? Is it because of any possibility of trapped
> moisture in the chip that could rapidly expand in high heat and damage
> internals? What's the worst case for not obeying this notice?
>
> * I've also heard of reflow soldering "profiles". What exactly are
> these profiles? Is it a requirement that I adhere to them for homebrew
> reflow soldering projects?
>
> * How do I apply solder paste on pads? Do I just squeeze it out of the
> tube and rub it consistently over the pads so that all of it is
> connected? Does a very precise amount need to be applied discretely on
> each individual pad? How is this done?
>
> * Where to buy solder paste, are there different types, what brand,
> what type? Should I use flux? Should I pre-flux the pads or apply flux
> and then solder paste?
>
> * I've also heard that it is wise to calibrate or know where your
> skillet/stove reaches a certain temperature. What temperature is good
> for reflow soldering? How do I measure this temperature?
>
> * How long should the PCB be on the skillet/frying pan during the
> reflow soldering process?
>
> I know these are a lot of questions, but I am very interested in this
> cost-effective do-it-yourself technique to solder surface mount and
> fine pitch components on PCBs with ease.
>

Short answers cause I'm busy today:

Solder paste:
http://www.dealextreme.com/details.dx/sku.7952

Kapton stencil:
http://ohararp.com/Stencils.html

(you can buy better solder and better stencils, but these work).

Toaster oven:
http://www.goodwill.org

Profile:
bake on "broil" until the solder melts, then open the door until it
freezes again.

Overall:  this method isn't worth the trouble and mess for single
boards, and isn't economic for large quantities (>50 boards).  For
just a few boards, it works fine.  It turns out that most components
aren't super-sensitive to heat.  Connectors, etc. made with plastic
are the most susceptible.

Solder paste is more dangerous than solder wire: it would be easy to
get some on your hand (it's sticky) and then ingest it.

Regards,
Mark
markrages@gmail
-- 
Mark Rages, Engineer
Midwest Telecine LLC
markrages@midwesttelecine.com
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