SMT Sizes and sources

FlyingFishFinger · 2007-10-20 23:29

Hi-
Can I do 0805 handsoldered? I've never done my own SMT board before, although I have done a little soldering (I think it was 1206, which wasn't too bad for me) at a summer job. And, where can I get small amounts of SMD resistors/caps/transistors (about 10 pcs)?
Thanks

Raf

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You've got to play the game.
You can't win.
You can't break even, except on a very cold day.
It doesn't get that cold.
~Laws of Thermodynamics~

parts-man73 · 2007-10-20 23:47

Mouser sells SMT resistor and Capacitors in small quantities. The smallest I've soldered by hand is 1206. I've not tried 0805, but I've heard that can be done by hand as well.

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Brian

uController.com - home of SpinStudio

FlyingFishFinger · 2007-10-20 23:49

Cool thanks I'll check with Mouser[noparse]:)[/noparse]

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You've got to play the game.
You can't win.
You can't break even, except on a very cold day.
It doesn't get that cold.
~Laws of Thermodynamics~

Phil Pilgrim (PhiPi) · 2007-10-21 01:52

0805s are easy if you have a steady hand, and 0603s aren't even that bad, once you get the hang of it. You'll need tweezers, of course. A good, lighted magnifier on a swivel arm is an asset, more for inspecting your joints than for doing the actual soldering. Solder wick will help suck up the big globs that invariably occur.

-Phil

uxorious · 2007-10-24 07:33

With the right tools for the job, you can handsolder 0201s. No that's not a typo and yes I have watched it done often with a Metcal iron and a scope. For the hobbyist, soldering SMT parts down to 0603 is usually the limits. Here's what you need:

1) The right size iron tip. A 700 degree fine point tip is typically what is used in PCB manufacturing houses to handsolder chip style passive components. The high temp is to minimize contact time to the part. Higher temp = less time to get the joint to reflow temp.

2) The right size solder. 0.015" diameter solder is the standard for 0805 and 0603. Using larger diameter solder wire will make it difficult to solder. However, you can cheat by applying extra solder to the tip and using that to create the joint on the part. This seems to be the common practice for hobbyists.

3) Proper tweezers. Don't use your wife's revlon tweezers. Buy a precision fine point pair.

4) Proper vision setup. Commonly this will be a microscope at 30x. For the hobbyist, it's typically a magnifying light. I have used the video output on my digital camera while in macro mode hooked up to a TV as well. This idea came from BGA rework machines that use cameras focused in at the side so you can see the balls collapse during reflow.

There are several sites that have good insight as to soldering smaller SMT components for the "average joe". One good one is:

http://www.circuitrework.com/guides/7-0.shtml

If I can find some of my links I will post them. One of my goals is to film one of the rework techs at my work doing all types of soldering so hobbyists can gain something from the knowledge readily available to people like me. It's a free time issue........

ps..
I hope no one takes offense to my use of the term hobbyist when comparing techniques. I am both a hobbyist (Basic Stamp junkie and keeper of an endless amount of cool-sounding ideas that I don't have the knowledge to make....yet) and a professional (Process Engineer in PCB Mfg, 17 yrs) so I mean no disrespect. It's just hard to bring tips to the table when I keep forgetting that most people don't have a $2000 microscope and $700 iron in front of them.

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~~ dRu ~~

uxorious · 2007-10-24 17:26

Here's a snapshot of one of my "prototypes" to show that you can handsolder small SMT parts. The SHT11 part is 0.2"x0.3"

It's a module using the Sensirion SHT11 temp/humidity sensor. I took a scrap piece of PCB material, notched it out for the SHT11 and 4 pin header, glued them onto it, soldered jumpers between them, added the pullup and 330 ohm inline resistor, and then added a 4 pin terminal block so I can try lengths of Cat5 cable. I did this for two reasons. One is to play with the SHT11 I happened to have without making an actual PCB and the other is to test how well the SHT11 communicates over long lengths of cable. My plan is to place 12 sensors at various locations in my house and a few will be the SHT11. The wires attached are "pluggable" wires like what Parallax sells that have a female on one end and a male on the other. Instead of plugging the module directly into my breadboard, these wires position it 15" away.

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~~ dRu ~~

Dave Paton · 2007-10-24 17:42

Raf-

I too have done everything from 2512 to 0201 by hand. I prefer to work with 0805s and 0603s though. The trick is practice, a small tip on your iron, a steady hand, good tweezers, and magnification. Oh yeah, tiny solder helps too. Really, that's the majority of the secret. dRu said it already, and I'm saying it again. It's not magic, just tedious.

-dave

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This is not a sig. This is a duck. Quack.

FlyingFishFinger · 2007-10-25 00:35

Ah this is good news people, thank you very much everyone. So is a Stamp done with 0603 parts?
I do not have the proper iron and magnification myself, but I do have access to a lab where they do have the tools.
Now I have to decide which size...>.<
By the way, what size does an SOT 23 correspond to in order of magnitude? (as opposed to, say, a SOT 223)
Thanks...forgive my lack of SMD knowledge[noparse]:)[/noparse]

Raf

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You've got to play the game.
You can't win.
You can't break even, except on a very cold day.
It doesn't get that cold.
~Laws of Thermodynamics~

uxorious · 2007-10-25 06:38

SOT= Small Outline Transistor. The SOT23 package is the typical SMT transistor package defined by a JEDEC standard. There are several variations now such as the SOT25 (a 5 pin device), the SOT223 you mention (a 3 pin and 1 tab device), and a SOT23-6 package which has 6 pins. Here is what I use for pictorials:

http://www.toplinedummy.com/SOT.html

Also, if you create a login with them, they have a really nice image library of parts for free.

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~~ dRu ~~

SMT Sizes and sources

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