Good soldering technique (or lack of it!)

[Bushbaby]

Hi All,
I'm on a roll with posts this morning.

I'm getting a wee bit concerned (maybe paranoid) about my soldering technique. I'm working on this wonderful Bush VHF90 soldering components to the tag strip that I've replaced. Unfortunately, the only replacement strip that I could get and would fit has just ONE tag (not two) along its length. The problem here is that there may be up to 3 components/leads that go to just the one tag.

I've had issues with solder (i'm using lead based solder) sticking to the tags although I've tinned each component lead or the end of the wire to be affixed.

I just hate it when the solder goes into a blob and doesnt stick (due to oxidation methinks!).

Any tips??

Thanks

Rob

[Andy M0FYA]

First I would rule out the solder (or more specifically, the flux), by trying another known good roll of a reputable make.

What sort of soldering iron are you using - is the temperature correct?

Andy

[Yorkie]

The first thing is that new old stock components - even if tinned, will be oxidised, so it's always a good idea to scrape tags and wire component ends and tin them. You're doing the right thing using 60/40 lead/tin solder rather than lead free. Always apply the iron to the tag to bring the tag up to temperature and apply the solder to the tag - never to the iron. The iron will always be hot enough to melt the solder, but it's the tags that need to be hot enough or you get a dry joint.

As to soldering several components to one tag, often you can solder them together first, just leaving one wire end to solder to the tag. Personally, when I can, I clip off the old component and leave 1/4" or so of wire left on the undisturbed tag. I then coil the end of the new component to slip snugly over that wire and solder them together. (you can use a sewing or darning needle to coil the end of the component wire).

I also have some non-corrosive liquid flux which I apply to stubborn joints to ensure that the solder flows well. I just apply it with a small artist's brush. (thats a small brush used by artists - not a brush used by small artists!). You find 50ml plastic bottles of liquid flux and sometimes syringes on t'internet. (It's water soluble, so any residue can easily be cleaned off with say a damp cotton bud).

Incidentally, when using stripboard it's most important to clean the tracks first with wire wool etc, or dry joints are a racing cert.

Hope that helps a bit Rob - glad to hear that you're finding some time for radio!!

[Bushbaby]

Hi Andy,
The solder is a 0.5kg reel of Multicore solder (I wouldn't think that its this). The soldering iron is an Aoyue 936 temp controlled running at 420C. Having look at the bit again its looking a wee bit blued and oxidised. Maybe I need a new tip for it.

Regards

Rob

[Bushbaby]

Yes, yes, yes of course the components and tag strip will be oxidisied due to age. Why didn't I think of this (doh!!).

Many thanks

R

[pwdrive]

Half the battle is a good clean tip in your soldering iron, keep the sponge nice and damp and run the tip over at very regular intervals to keep clean, new or NOS tag strips should take solder no problem, pre tin first, some original fluxes present in joints on old sets can be problematic, if that is the case then all original stuff should be sucked or wicked off, cleaned, then re tin everything with new solder, regarding getting several componet leads to one tag, most tags will take 2,3 or even 4 component leads when fully cleaned up, wrap the leads half a turn or so to the tag if you are looking for originallity, if not just poke 'em through by about 2 to 3 mm and solder up, the joint should be fine if everything is up to temp and a decent solder is used, I was taught to make both a mechanical joint as well as a soldered one ie: wrap components through tags, but in my experience this is not really needed if soldered correctly, to wrap or not to wrap is a personal choice.

Lawrence.

[Joe]

There's a special place in Hell for wrappers!

- Joe

[Skywave]

You have a good make & type of solder, so we can eliminate that as a possibility.

Apply fresh solder direct to the tip of the iron: does it 'wet' the surface of the iron, or just remain as a molten blob on the tip? If the latter, the tip of the iron needs cleaning or the iron is not to the required temperature. With those variables out of the way, examine the surface of all the metals that you want to solder together: all surfaces must be clean and bright. The lead-out wires of old components frequently fail to pass that test and sometimes reliance on the flux in the solder is insufficient to effect the required cleaning during the final soldering process. So if the surfaces to be soldered are heavily tarnished or corroded, take a piece of medium grade emery paper and scrape the surfaces to be soldered with that cloth until they are bright and clean. Then apply fresh solder to those surfaces, prior to any attempt to make the required final solder joint.

You are now able to assemble the final joint to be soldered with the knowledge that a sound soldered joint will ensue.

HTH.

Al.

[Steve_P]

Try doing it my way. Wind the wire round the junction (or the wire to one of the components) and cover the lot with Solder Paste. Then use the iron to melt the solder paste and make the join.

It works for me!

Cheers,

Steve P.

[AlanBeckett]

There's a special place in Hell for wrappers!

- Joe

'Fist make a sound mechanical joint'

Alan