Surface Mount Components question

[sirkut]

What size tip is suggested when using surface mount components or is there a special soldering iron for small components. I was curious about decreasing the size of something I'm building.

[Aharon]

I think a really fine tip would help.
Aharon

[Ansil]

weller makes a micro tip iron for this purpose it is like 40 bucks at my local electronics shop..  i have used one before and it makes a regular soldering iron i even the ratshack micro iron i usually use look like a baseball batt.

[Johan]

there are special tips made for soldering SMD's, but unless youre really shaky, you can probably do it with any smaller tip. I do a lot of soldering at work, both SMD and regular through-hole and I never bother to swap tips...always using the 2.4mm Weller standard.
what help though, is to use something called "rework solder flux". its just what you'd expect..solderflux....comes in a little sharpie-type pen and you just "paint" where you're going to solder..makes it esier and faster..

Johan

[gez]

The Feb edition of Everyday Practical Electronics had a nice little article on SMDs.  I think it comes out a month later in some parts of the globe so you might still be able to get a copy.  Plenty of advice on soldering etc.

www.epemag.wimborne.co.uk

[Ansil]

what bout one of those little pens we were talking about the ink that is conductive for smt's.  

use a dab of crzy glue to hold the thing on there and take the leads with the pen..???  feaseable???

[Johan]

what bout one of those little pens we were talking about the ink that is conductive for smt's.  

use a dab of crzy glue to hold the thing on there and take the leads with the pen..  feaseable???

...someone has to try it before we know, but my guess is that the "traces" would have higher resistance than what we want, since it is intended for very short distances in repair of traces... and also I am not sure it would be sturdy enough to be kicked around the way a stompbox sometimes gets...( my boxes often looks ten years old after about a month... :cry:  )

Johan

[R.G.]

What size tip is suggested when using surface mount components or is there a special soldering iron for small components.

There are special small irons, tips, etc. but I always just wind a bit of heavy solid copper wire (#12 or #18) around the tip of my iron after filing a point on the free end. Dope it well with solder and the free end makes a good low-wattage small point iron for SMD. It helps to get really fine wire gauge solder though to avoid loading too much on the connection and making shorts.

[Ansil]

what bout one of those little pens we were talking about the ink that is conductive for smt's.  

use a dab of crzy glue to hold the thing on there and take the leads with the pen..???  feaseable???

...someone has to try it before we know, but my guess is that the "traces" would have higher resistance than what we want, since it is intended for very short distances in repair of traces... and also I am not sure it would be sturdy enough to be kicked around the way a stompbox sometimes gets...( my boxes often looks ten years old after about a month... :cry:  )

Johan

actually the traces i was only talking about doing like a quareter inch or so. to some real traces..  but i see yoru point..

[Mike Burgundy]

I prefer a chisel-point tip, as small as you can find (I have a 2.4mm, and one even smaller), but I really prefer not to hand-solder SMD. Solderpaste (microscopic balls of solder in a solution of flux and something else, creating a paste) in a syringe - well-designed PCB, dab the appropriate spots, place components with tweezers, and bake in an oven is my hands-down fave. If the PCB is well-designed the components will even self-align on the surface tension of the drops of solder. Repairs and sloppy joints I take on with the iron.
Watch your temperature-control and timing though.

[javacody]

What would qualify as a well designed pcb for smd?

[puretube]

Peter (or else...) :
do you happen to know, whats the "liquid gold" inside that solder-paste,
which makes it "pasty",
and raises the price to 10$ per 10g for Sn62 Pb36 Ag2,
compared to "regular sodder" <1$ per 10g for Sn95 Ag3.8 Cu0.7 ?
(can`t be the silver, that`s why I compared these to prices/products
from a popular european mailorder - sure there are cheaper sources...).

wanna mix my own compound...


btw.: Elektor had a nice SMD oven article, last month:
http://www.elektor.de/default.aspx?tabid=107&ProductID=4073

[Peter Snowberg]

Sorry, I don't know anything about solder paste chemistry, but I'm sure the mechanical process of powdering the allow has sometthing to do with it. :?

[Paul Perry (Frostwave)]

I think the expense of that solder paste, is the difficulty of making the tiny (uniformly sized) alloy paricles, and then coming up with (relatively) non-toxic chemicals that will give the physical characteristics that let you screen print with it, plus bake it & have everyting work "just right". There are whole books on the formulation of SMT solder paste, plus countless patents.
Just using very fine 'ordinary' solder (lead or non-lead) is fine for DIY SMT work.