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Ross77
16-08-2009, 12:40 PM
Following on from another thread I think that using smd components will be very usefull.

Anyone else use them? what are the advantages/ disadvantages?

Cheers

ptjw7uk
16-08-2009, 01:25 PM
Advantages are they are all of a uniform size for same value or component, have no leads to cut or bend and tend to lie nearly flush which gives most of the disadvantages they are not easy to solder on as they are small having very little in the way of packages or leads.
They are also designed to be flow soldered in that they are glued to the board and then flow soldered by machine but it can be done if you have the right tools and a steady hand.

peter

tumutbound
16-08-2009, 01:40 PM
As I have some SMD soldering to do soon (Shumatech DRO-350 upgrade), any information, pointers, warnings etc would be welcome.

ptjw7uk
16-08-2009, 01:59 PM
do a web search it will bring up some interesting ideas.
http://www.engadget.com/2006/03/07/how-to-make-a-surface-mount-soldering-iron/

This one is for the expert
http://hackedgadgets.com/2008/01/14/surface-mount-soldering-tutorial/

Run the video
Notice the extra equipment (microscope these bits can get small) if you are serious about smd but usually for the odd resistor or capacitor a good soldering iron will suffice.

Peter

Robin Hewitt
16-08-2009, 02:14 PM
You can hand solder .05" pitch.

I usually tack one pad in each corner then melt and jiggle until everything lines up. Finest soldering iron bit, 26swg multicore, wipe the bit regularly so the solder can't build up enough for a blob.

Finer pitches for hand assembly you need a hot air blow gun, not butane powered, and solder paste...

If it's small enough to melt all the pads simultaneously, tin the pads, remove any bridges then apply the component. Surface tension will pull it in to place when everything is molten.

Too big to melt all at once, tack two corners, apply paste and run the hot air gun down the line. If adjacent pins bridge apply excess solder then grab your recoil less solder sucker. You do have a recoil less solder sucker, don't you?

Tin lead solder, ROHS be blowed. It must measure something if it's CNC, measuring instruments are exempt :beer:

tribbles
16-08-2009, 05:16 PM
You can hand solder .05" pitch.

I hand-solder 0.5mm pitch (0.02") :tongue: I wouldn't want to go any lower than that (and it does involve desoldering braid). It can be a bit hit-and-miss without the braid (mainly miss), but I did manage it once.

I use the same technique as the 0.05" pitch (2nd video above is really using the same technique as wave soldering), but then the braid cleans up the shorts that you inevitably get (wave soldering's only really good for 0.8mm and above).

If you do use the 2nd video link, then it does take a bit of guts to do it the first time (best to practice!), and it works really well if you have solder resist on your board (I don't, but it's still okay - especially with desolder braid to clear up the mess!).

Robin Hewitt
16-08-2009, 07:08 PM
I do .025" but it ain't pretty :whistling:

Ross77
16-08-2009, 10:43 PM
Thanks All :beer:

That guy in the 2nd vid makes it look so easy.....

Has anybody made the hot air gun from the first link?


You do have a recoil less solder sucker, don't you?
No I dont. just a recoil one. I take it that a recoil less one is what they modded to make the hot air gun?

tribbles
16-08-2009, 10:53 PM
I do .025" but it ain't pretty :whistling:

Prettier than my 0.02" without solder resist (cheat!) though :smile:

Note that the two pins that look like they're shorted aren't - it just flux that didn't come off the third cleaning I did with it.

tribbles
16-08-2009, 10:55 PM
I take it that a recoil less one is what they modded to make the hot air gun?

I would imagine it's easier to reverse the direction of the airflow than a recoil sucker.

Ross77
17-08-2009, 12:52 AM
I would imagine it's easier to reverse the direction of the airflow than a recoil sucker.


Ok now i'm confused. Isnt a recoil sucker like a pen, Press the plunger down and then hit the release button to suck?

Robin Hewitt
17-08-2009, 11:01 AM
They look very different, the sucker has a trigger to turn on the pump, the blower is permanently on so you can set the flow and temp.

I got mine cheap on flea-bay :beer:

Ross77
17-08-2009, 07:43 PM
Cheers,:beer:

I'd better start looking then. Any makes to look for or avoid?