[Coco] Run of RGB2VGA boards

[Zippster]

I usually use a tip like this one for drag soldering.  <https://drive.google.com/open?id=0B1sgl615FlGnRmFEQURPLXV4emc <https://drive.google.com/open?id=0B1sgl615FlGnRmFEQURPLXV4emc>>
I’ve seen ones in this shape that have the concave surface, I haven’t used used them, but they look like they’d
work well except they might have a tendency to carry too much solder.

I use Amtech 4300 flux in the 10cc syringes. It’s great for SMDs, and somewhat tacky which helps hold small parts
in place when positioning them.  Fantastic for cleaning up through-hole solder joints as well.

I tried the hot-air method when I first started trying SMT.  It worked ok, but you often have to clean things up with
a soldering iron afterward.  Also, there's the inconvenience and mess of using soldering paste (which expires and
becomes unusable).  After I found I could do everything with an iron, there was no contest.  I want nothing to
do with hot-air except for removing SMD ICs and shrink tubing (which it is perfect for).

I find that now I use only two types of tips for all my SMT and through-hole soldering, the type linked above,
and a chisel tip like this <https://drive.google.com/open?id=0B1sgl615FlGnVmROZmE3dnlnXzA <https://drive.google.com/open?id=0B1sgl615FlGnVmROZmE3dnlnXzA>>
Surprisingly, I don’t like the traditional conical type for anything anymore, the chisel tip gives me more control.

SMT soldering is different than through-hole, which is what I was used to as well before getting into it.
Mastering it basically boils down to being able to control that surface tension, or capillary action as Mark puts it,
which is done through a combination of temperature, flux, shape of the tip and how you move it.

It’s definitely worth learning, it will improve your through-hole soldering skills as well.
You can do everything but BGAs with a temp controlled iron, good flux, and the right tip (and any needed
magnification).

- Ed


> On Sep 15, 2015, at 6:51 AM, Steven Hirsch <snhirsch at gmail.com> wrote:
> 
> On Mon, 14 Sep 2015, Zippster wrote:
> 
>> You just have to touch the tip of the soldering iron to your solder to get a small amount on the tip.  It doesn’t take much.  The flux applied to the pins before hand keeps the solder from getting “sticky”, and the surface tension of the molten metal pulls the excess off of the pins.
> 
>> It’s actually surprisingly easy once you get used to it.  The hardest part ends up being aligning the chip before tacking the corners.  I found it nerve-wracking and frustrating at first, going with my first instinct, which was to try and precision solder individual pins.  But after learning drag-soldering it’s just as easy (or even easier) than through-hole pin-for-pin.
> 
> I have seen special tips with a concave area designed for "drag soldering".  Are those worthwhile?
> 
> Also, what brand and type of flux do you use?
> 
> I invested about $400 in a BlackJack hot-air reflow station about five years ago, but never had much luck with that either.  The YouTube videos always make it look so simple...  Other people slather on the solder paste, wave the tool over it and - bingo! - perfect solder flow.  When I do it, the solder ends up being blown underneath the chip in tiny little globs where it shorts out everything.  I'm guessing it's a matter of finding exactly the right combination of temperature and air-flow, but never can seem to dial it in.  At least part of my problem is a fear of damaging the parts and / or board by overheating.  But, I'm getting the impression that modern VLSI semiconductor components are not all that heat-sensitive.
> 
> Any, maybe it's a generational thing?  I grew up with a soldering iron in my hand and never had any issues with "traditional" soldering.  SMD just seems to be my nemesis.
> 
> 
>