i really made confused about this term. what is it looks like? anyone has a picture so i can mean it more correctly? i mean a solder cold joint aka dry joint.

btw: anyone know what LCO and LS term mean?

thanks
Posted on 2003-04-01 05:00:05 by dion
Hello,

Well, basically, a solder cold joint is something you get
when you didn't do the job properly.... it mean that the
solder have no propper contact with the pcb. Cold joint
are bad electrical contact, may result of a failure of the
circuit.

go check there, you'll some pics of what are a correct
soldering vs bad ones....

http://www.epemag.wimborne.co.uk/desolderpix.htm

regards
etherlord
Posted on 2003-04-01 07:29:11 by etherlord
Cold/Dry joint occurs when there is no 'wetting' between surfaces. Usually, failed to heat the joint long enough for the proper flow of solder between surfaces.

Regards, P1

I did teach this at one time ( along time ago ). You think I could found something. Well, don't let your spouse clean your stuff out.
Posted on 2003-04-01 08:46:01 by Pone
Soldering is FUN!!

A classmate of mine soldered his project so bad, he accidentally dropped it from his desk and half the joints broke!

A REALLY good solder will be so strong that if you try to tug the things soldered apart, they will break before the solder joint does. When you've reached this level, all you need to learn is how to solder to a low-quality PCB board whose copper will lift from the board if you heat it too much - this makes you solder faster and stops you from breathing while soldering.
Posted on 2003-04-03 20:21:31 by AmkG
Ya some quick tips here.. keep some soap-free steel wool on hand to clean up the copper surface your soldering to. I usually do thins once before i get started.

Copper oxidizes fairly rapidly. Oxidized copper acts more like a resistor, as well solder doesnt form and stay on the pads well. Before a big solder-a-thon its good to steel wool off the pads you intend soldering to (till it shines bright copper). Frome there. Try to aviod direct touching these areas excesively with your hands, as the oils from your skin will also hinder your soldering to some extent.

:NaN:
Posted on 2003-04-03 22:59:53 by NaN
After soldering, avoid blowing on the soldered joint.

Try to make sure that the place you are working in is well-ventilated but that there are no actual drafts/wind blowing your work. Have your desk fan target your head, not your work.

As much as possible, heat the items you are working on, NOT the solder. The wire should heat the solder, not the other way around - there is some weird chemical process at work here in which the solder actually melts the wire and forms a chemical bond with it, which won't work if the wire is too cold. When working with low-quality PCB's (such as what I described, where the copper layer disconnects from the actual board if you heat it too long), you better be fast, heat the wire, as soon as the solder melts, get the solder out and then the iron as soon as possible.

Add a *thin* layer of solder on your iron to 1) keep it clean and 2) facilitate the transfer of heat from iron to wire. DON'T try to leave the layer of solder on the wire, this increases the chance of cold solders.

Make sure the iron is VERY hot before starting to solder.
Posted on 2003-04-04 02:23:20 by AmkG
thanks a bunch guys, i really appreciate it :grin: :grin:
Posted on 2003-04-04 05:11:07 by dion
one more thing...

good solder looks like a volcano...

and bad solder looks like pumpkin (or something) ;)
Posted on 2003-04-04 12:29:45 by flotsam
If you're looking for a decent iron at a low cost, I suggest the Hakko Dash N452. For home I've got the N452-T-I tip. For work, where we occasionally install chips with 0.5mm pitch, I use the N452-T-1C.

I prefer using a wool tip cleaner. You'll want to get the stand to. Jameco #156777 The wool cleaner doesn't work to well for cheap irons.

If you can afford it, the $110 IPC solder standard IPC-610 has many usefully descriptions and pictures for Class I, II, and III solder work.

A bottle of liquid Rosin Flux can be handy the harder to solder wire and joints. If you need to clean rosin flux, Isopropanol usally works, Ethanol works a little better, and Methyl-Ethyl-Ketones always works.

A good solder joint will be shiney and have a nice fillet. Avoid excessive solder; a ball of solder over a pin can hide a bad joint.
Posted on 2003-04-09 03:50:46 by eet_1024
I know i repeat the already very good explaination :) Just a little draw i've done now, to help understand dry joint trouble...












In the picture you see a good joint (lead well attached to both pcb and terminal) and a bad dry one, similar to a ball.
If you heat at the same time component terminals and pcb pad you can have a good joint. As already said, solder flux help a good joint.
Posted on 2003-04-10 07:09:09 by Bit7
thanks a bunch again guys :grin:
Posted on 2003-04-13 00:56:17 by dion
Dion,

I learnt this much back when I had enough eyesight to work on analogue audio that a copper tipped iron that you cleaned and tinned gave safer faster solder joints that the temperature controled iron coated soldering irons.

A lot of later stuff is too small to do this way but if you are using discreet components and op amps, fast clean soldering reduces the heat transfer to the component and reduces damage to the circuit board.

Regards,

hutch@movsd.com

Shame actually, I still have a few grands worth of 10 year old op amps and components for making audio, I just never get the time to play with it any more. Its been that long that I turned my osciloscope on it probably does not work any longer.
Posted on 2003-04-13 08:04:12 by hutch--

Dion,

I learnt this much back when I had enough eyesight to work on analogue audio that a copper tipped iron that you cleaned and tinned gave safer faster solder joints that the temperature controled iron coated soldering irons.

A lot of later stuff is too small to do this way but if you are using discreet components and op amps, fast clean soldering reduces the heat transfer to the component and reduces damage to the circuit board.

Regards,

hutch@movsd.com

Shame actually, I still have a few grands worth of 10 year old op amps and components for making audio, I just never get the time to play with it any more. Its been that long that I turned my osciloscope on it probably does not work any longer.


Sell it to me for shipping and 1 ozi buck.
Posted on 2003-04-13 22:32:48 by IwasTitan