Soldering 101 for Audiophiles

Dear CWLondon,
I recently built my first kit, a KandK Phono Preamp, and I indeed Googled "Solder" and after hours of research here is a summary of my findings.

Like everything else in the world, nobody agrees on how to solder. I might summarize my findings, and of course others probably have different data, as the following two camps of theory.

Theory One: Affix the soldering iron tip to the component and don't ever touch it directly to the "solder" wire. This means: a) place the hot iron tip against the component lead or wire, b) place the solder wire also against the component wire or lead - very close to, but not against the iron tip itself, c) when the tip heats the component lead enough, the heat will pass through the component lead to the solder wire and it will begin to melt, and d) flow the amount of solder you want onto the joint or connection and remove the solder and the iron tip at the same time. If soldering the lead to a heat sensitive component, place a wire clip or similar "heat sink" on the component lead between the joint to be soldering and the body of the component to draw excess heat into the heat sink to preclude it from overheating the body of the component. I found this can slow the solder process, since the heat sink may draw some heat necessary to flow the solder into the heat sink itself.

Theory two: a) place the iron tip at the joint to be soldered, and b) touch the solder wire against the tip of the iron to cause it to flow onto or into the joint, and c) after flowing the solder remove the solder wire and iron tip at the same time. This theory places much less heat into the components and I found takes roughly 20% of the time to solder each joint compared to theory one.

Component Leads Theory One: Component leads do not need to be cleaned or treated with an abrasive before soldering the joint. The theory is that the soldering is sufficient to make the connection, that treating the leads with alcohol or some other cleaning material or abrasive strips them of a layer of protection, which exposes them to oxidation (rust).
Component Leads Theory Two: To make the best connect and allow the electrons to flow with the least resistance, strip the lead ends with an abrasive (such as sand paper) and wash them with alcohol. Exposing the unoxidized flesh of the component wire will allow for a better bond of the solder to the component wire, since dirt or oxidation will not sit between the component lead and the solder being applied to same.

I don't know which theories are better, but i went with the more heat solder theory and the clean with alcohol and abrasive theory and my KandK sounds great. I did use a heat sink just on those components that Kevin said were heat sensitive (maybe two in the whole kit). Is this the ideal way? I don't know.

Kevin suggested Cardas solder, which i found flows very well at about 680 to 700 degrees and i found a temperature controlled soldering iron to be vastly more user friendly than one with such control. If fact, as a beginner i would really not recommend trying the work without a temperature controlled iron. I found that Rat Shak solder, at the same temperatore, wants to crawl up the soldering iron tip (somebody else would have to explain this).

As a beginner, i bought two really cheap electronic kits (like $10 each) from Rat Shak for practice, which helped me out a lot before undertaking the kits. I am now building an Audio Note DAC. I also found a solder removal braid to be useful(Rat Shak's works fine) and a small tin of solder tip cleaner (also Rat Shak works fine) to be very helpful.

Each time you turn off the soldering iron or let the iron sit idle for a while, you should touch the solder wire to the tip of the hot iron and melt some solder all around the end of the iron tip to prevent oxidation of the iron tip.

Some people recommend that just before you touch the tip of the soldering iron to the component lead in either theory above, that you touch a smidgeon of solder to the hot tip in order to "pretin" the tip. They believe this shortens the time duration for which to put heat into the component lead, thereby causing the solder to flow faster with less risk to the component. Generally, I did not do this, but i did tin the soldering iron tip each time i set it aside and i cleaned it with a damp sponge every time before soldered a joint.

Hope this helps. I'm sure others will have better suggestions, but these are the things I learned from my Google search. I would love to hear suggestions in addtion to my rudimentary technique. Jeff

Much useful info here. I find I can do virtually any soldering job, from thick wire down to tiny surface-mount ICs, with two irons: 40W Radio Shack and Antex 15W mini-iron with .012" gold needle tip from www.telephoneparts.com. The gold needle needs little tinning & does not deteriorate with use.

Antex 15W mini soldering gun:

ANT-C/3U mini-iron with 3-prong grounding
ANT-8G .012" needle gold tip

Cardas no-lead solder sounds great but requires too much heat to use safely with surface mount components or when soldering directly to IC pins. Be aware that with no-lead solder a good joint looks dull just like a bad joint.

Good low temp silver-bearing solders include WBT and Radio Shack p/n 64-013. The RatShack solder is also a thin diameter .022", which can be essential for small components & PCB pads.

Finally, a good tractor lamp with an illuminated magnifying glass from Staples, a small table-top vice, a Ratshack mat with grounded wrist-wire, and a RatShack Helping-Hands arms with alligator clips to hold things in place.

jj2468

Nice post - your info has brought back memories of the man who helped me build my Hafler amp when I was in junior high school. I was hopelessly baffled by the instructions, and my Dad contacted him to help me out.

And yes, I now recall he showed me a few simple demonstrations where he would heat the wire with the tip of the iron, hold it there for some heat, and then stream the solder onto the joint by touching it simultaneously against the iron and the joint, and withdrawing the solder first, and then the iron.

He was the kind of guy who looked like he knew how to solder, while also looking like he didnt know how to tie a tie, which in this instance I took as a good thing.

He didnt seem to use any abrasives or solvents, but then again he was not an audiophile - just a regular electronics geek.

I think this thread is a great resource for someone like me starting to solder.
I'm glad cwoldon asked the question. I started watching the tangent video, read everything here, and I feel I'm much better about soldering.

1. Buy solder and flux and read the directions. "Michael Percy's" website has a good selection and reliable information. The 3 or 4 types that come up are all reputable and as usual folks have their preferences and reasons. If I were you I'd buy the solder with a low melting point as ease of use is what you obviously need; however any of them will provide a satisfactoty result-if used properly. Percy is reliable.
2. Prep the joint spot on the tweeter.First remove the old wire where it it attached to the tweeters by bringing the hot tip(preheat the tip) of your pencil/gun(hereafter called an 'iron') to the joint. Touching the joint heat it quickly until a gentle rub from a piece of cloth causes the old wire to be released. I like to remove the old solder at the same time rubbing the cloth on the hot spot. The old solder does not have to be fully removed or perfectly clean. (Your pencil/gun "must" be hot enough so this is accomplished in a few second or you risk heating areas nearby-which you'do not' want to do- this is what others are warning about. "If" your pencil will not heat the target quickly(i.e. to not heat up surrounding area) then I would obtain(rent) a gun with a hotter tip.) Quickly reheat the spot until a dab of the new solder wire melts onto it. This piece is now ready.
3. Now prep the wire end. Cut the insulation off the tip of your new wire - perhaps an inch. Preheat you iron. Heat the end of the wire quickly until touching the solder to it results in a drop of solder melting into the tip of the wire. Remove heat as soon as the drop melts into the wire.The wire is now ready.
4. Align and touch together the 2 items to be soldered exactly the way you want them to be permanent.
5. Bring the hot iron to heat the 2 items simultaneously until the solder wire touched to them melts a drop which fuses the 2 together. Immediately remove the iron and allow joint to cool naturally - without disturbing it for the 'say' 5 seconds it take to stabilize. You should now have a stable soldered joint. I hope this makes sense for you. Feel free to ask questions so we get you back to enjoying your system. Best wishes. Pete