27 Apr
2015
27 Apr
'15
10:32 a.m.
Thirded; I spent a few summers doing prototype assembly ... mostly SMD but
some through-hole ... in my dad's lab when I was home from university and I
got good results with just a very fine-tip soldering iron and a good
variety of precision pliers (or sufficiently small and well-callused
fingers, LOL) especially on simple little two-lead parts like resistors and
caps ... my hint for these is to get a little bit of solder down on one of
the pads first, then heat that up and re-melt while you maneuver the
component into place; hold for a second to be sure you get a good bond,
then it'll be good and stuck there while you solder the other side down
more "traditionally"; heat the junction between pad and part lead and then
get the solder in there... You can take the same approach with SOICs ...
pre-solder a pad and remelt while you get the IC into place; that will hold
the part in there while you get all the other leads using common soldering
techniques. I've never done BGAs ... that's where you start to need the hot
air. Using flux can make it easier for you, but you don't necessarily need
it if you have a good iron and you're "in practice" :O
I've seen these SMD aluminum electrolytics everywhere ... Apple equipment
is full of them ... I've also seen them in SGIs, Suns and ... I will defer
to someone who's looked at their NeXT Cube logic board more recently than I
... although so far, knock-on-wood, I haven't had any trouble with them
across all vendors worth of gear that I've got stashed.
Best,
Sean
On Mon, Apr 27, 2015 at 2:22 AM, Tothwolf <tothwolf at concentric.net> wrote:
On Mon, 27 Apr 2015, TeoZ wrote:
You can do capacitor repair easily enough with just a soldering iron. I
have reworked dozens of mac and PC motherboards
over the years (and a few
video cards).
I suspect real hard SMD work (video chips and southbridges) might be
popular down the road to collectors.
Seconded. I don't own a hot air system (yet) and I do plenty of SMD work,
including 0402 stuff and sometimes smaller. The single most important thing
to have is liquid flux such as flux pen. You also really want a wide tip
(chisel, knife, or hoof) on the soldering iron to carry molten solder to
the joint. This is totally different from through-hole work since you are
applying flux directly to the joint before applying solder. With enough
flux, the right amount of solder just wicks right into the joint (yes,
really!). Even fine pitch QFPs don't give me any trouble.
The only thing I've yet to touch are BGA packages, and I'm really not
looking forward to the day when I have to...
Still...I see a lot of people using SMD tantalum parts to replace SMD
aluminum electrolytics, and after seeing so many of these SMD tantalums
burned to a crisp after they developed internal shorts, I certainly
wouldn't use them for general purpose bypass work. SMD solid polymers which
do not exhibit that type of failure mode are readily available in the same
case sizes (round cans) as the original aluminum electrolytics and are also
available in the same case sizes as SMD tantalums. Not only that, but solid
polymers are less expensive than tantalum parts.