[sdiy] Starting with SMT hand-soldering

[Elby Designs]

I think the question on the number of pencils falls down to how much work
you are doing and the variety. If all you are (mainly) doing is soldering
SMT parts then a single pen with a fine (I prefer chisel) tip is all you
need. It is useful to have a selection of tips so that you can handle bigger
(or even smaller) pins.

If you are also soldering a number of through-hole components, especially
the bigger stuff like connectors, power transistors, relays etc, then you
should also have a larger tip.

If you are doing rework then a tweezer pen is useful. Small tips for your
0508, 1206..... packages and wider blade tips for small ics and
semiconductors (SO-n, SOT....).

No it depends on the volume of work. For occasional changes of tips, 1 power
station is fine. If you can afford more than 1 pen/tweezer, then get them.
This will allow you to simply unplug and plug-in pens with different tips as
you need them. Modern day stations heat up very quickly so you are only
waiting for a few seconds between changes. Some more expensive system allow
you to change the tip in the pen. This is okay but I find this more
frustrating than changing pens because you have to handle hot tips. The
ultimate is a power station for each pen/tweezer, then you can go flat
out......

Remember, if working with lead-free (yuk) you must switch off or turn down
your irons when not using them. Always clean them and re-solder the tip when
turning off. With (good-ole) lead solder, just clean them. Helps to turn
down the heat but less important than with lead-free.

To remove larger chips like SO-14 and up, a pair of wide blade tweezers are
best for de-soldering. If you can afford a rework station then you can buy
`heads' that are designed for each package - this is where it gets expensive
because you really need a different head for each package and there are a
lot of varieties...... For 4-sided devices then you need the rework set-up.

0805 is the best size to work with and the more common for many components
although there seems to be a trend towards 0603 and smaller. 0603 are my
limit as I hate working with anything smaller. On that scale, the quality,
style and size of your tips is critical. There are dozens of styles to chose
form and you will need to experiment to find the best that works for you.
For 0805, SO-n, SOT and up, I find a small chisel tip works best, especially
if you are doing lead-free. With a small enough tip it is very easy to
solder individual legs of an SMT ic and I recommend that way over the flow
technique mentioned before. Components are temperature sensitive and unless
you are proficient and confident, I would not opt for the flow method.

A good magnifying lens with light is very useful and a great aid to good
soldering on these small beasties.

As mentioned by others, I too like to solder one leg of two leg devices
first, check for any that are not aligned squarely or centrally to their
footprint, and then return soldering the other leg. ICs are done by tack 2
diagonally opposite legs, checking for alignment of all pins and then
soldering them. I prefer to solder one leg at a time and can do this really
fast with the aid of a magnifier. Again, a good sized and shaped tip is the
clue.

If you can, stay with lead solder, EVERYTHING just flows and goes better....

Best Regards
Laurie Biddulph
Mobile: 0400 257 645
Web: www.elby-designs.com


-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl
[mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of Justin Owen
Sent: Friday, 29 October 2010 9:19 PM
To: Synth DIY
Subject: Re: [sdiy] Starting with SMT hand-soldering

Thanks to everyone that replied to this - very helpful, much appreciated.

Two follow up questions:

1) A couple of you mentioned multiple irons - is that for a variety of tips
or is there some mad two handed soldering technique you've got going. No -
I'm serious.

2) Temperature controlled iron - nice if you've got it or vital?

Thanks again.

Justin



-----Original Message-----
From: Barry Klein [Barry.L.Klein at wdc.com]
Received: 28.10.2010 18:53:42
To: Justin Owen; Synth DIY
Subject: RE: [sdiy] Starting with SMT hand-soldering

I do rework of small external storage boards with smaller parts than
1206.  Get two irons with hot pencil tips plus one iron that is heavier duty
with a wide blade tip.  Get some liquid rosin and find someone that sells
seringes that can hold it.  Get smallest solder you can find.  Lead based
will work best but you may be forced to use leadfree.
Get a stereo microscope if you can.  Cheap crap one is probably fine.
No need to bother with parts glues or pastes.
Get some good fine point stainless steel non magnetic tweezers.
At this point it is just go ahead and solder the stuff.
You'll be amazed at the control you have while looking through
a microscope.  Use the rosin ahead of time on multipin chips
and the solder will just flow where it needs to go.  Then clean off
with a flux cleaner spray.

Barry


-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl
[mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of Justin Owen
Sent: Thursday, October 28, 2010 10:41 AM
To: Synth DIY
Subject: [sdiy] Starting with SMT hand-soldering

Hey again,

I'd like to try my hand at laying out and hand-soldering an SMT board and
thought I'd stop in here to see what advice I could get from those that have
done it.

I figured I'd start with 1206 parts but I might get some 603 bits just to
check the form, I'll stick with my current iron until I know it's not
suitable but I might get a decent magnifying glass on a stand, I've checked
YouTube for a few tutorials...

...anything else? I'd be particularly interested in any advice with regards
to laying out the board - if there is any.

Ta much,

Justin

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