💾 Archived View for pwshnotes.flounder.online › gemlog › 2024-05-30-soldering.gmi captured on 2024-08-18 at 17:15:43. Gemini links have been rewritten to link to archived content
⬅️ Previous capture (2024-06-16)
-=-=-=-=-=-=-
I'm terrible at soldering. And, I ruined two soldering iron tips on my small project this week.
I did collect some useful information while researching. But, I don't have a complete set of advice that works.
Here's what I learned so far.
A soldering iron is a tool for heat transfer.
Much of the advice given about soldering technique relates to heat transfer. And, without understanding this, that advice can seem confusing or irrelevant.
For example, "tinning" the tip of the soldering iron does several things related to heat transfer. Tinning enhances heat transfer by creating a continuous bridge of metal to transfer heat from the iron into the joint. Tinning prevents oxidation by sealing the tip of the soldering iron with solder. Oxidation greatly reduces heat transfer. So, that's why we are interested in preventing oxidation. Oxidation turns the tip of the soldering iron dark as the soldering iron heats up and the metal interacts with the oxygen in the air.
The tip of the soldering iron can be thought of as the entire piece of metal sticking out of the heating element on your soldering iron.
But "tinning the tip" doesn't refer to this, so far as I can tell.
Instead, it is important to understand that the tip is made of a core of copper meant for heat transfer; the copper is clad in elemental iron, which is also meant for heat transfer; and, finally, the iron is then plated with nickel and chrome which is meant to keep the tip free of solder. Only the extreme edge of the tip exposes the iron cladding. My understanding is only this small, exposed area is used to transfer heat. In my experience, the plated sides of the tip are not a good conductor of heat.
When you attempt to tin the plating (as I did), the solder will run off as it is meant to. Where I did succeed in tinning the side of my soldering iron tip, I just ruined the tip by creating pits which exposed the iron and copper inside. You should replace a soldering iron tip when it becomes pitted.
Soldering iron tips are not a standardized size. And, especially, the cheap hobby irons I've bought are difficult to find replacement tips for. I found one iron at my hobby shop where replacement tips are for sale. That's the iron I bought after I ruined the tip on my first iron.
There are much higher quality irons like the ones from Hakko and Weller. I have no experience with these. I can only assume the higher quality translates into less frustration.
While I've focused on technique, there is also advice about the results.
On printed circuit board through holes, a good solder joint is described as a shiny volcano with the component lead sticking through the top of the volcano. Wire-to-wire solder joints should also be shiny. And the fibers of stranded wire should absorb solder during the tinning process and while being joined. (Yes, wires should be tinned before joining.)
Two common defects in soldered joints are cold joints and dry joints.
A cold joint is one which was never properly heated. The result is a fragile connection which will fail early. A simple fix is to heat the joint and melt the solder. Then, leave the iron applied for an extra second to give the metal a chance to properly bond (known as wetting). The solder should take on a smooth appearance and maintain its smoothness after cooling. Solder should flow into and fill any gaps in a joint.
A dry joint is just a connection without enough solder. On a PCB soldering pad, there might be a hole where the solder has not completely covered the pad. When connecting components or wires, there might not be enough solder to fill all the gaps in the joint and create a solid and reliable connection. A simple fix is to reheat the joint and to add a little solder at a time until these gaps are filled in. It is possible to add too much. In that case, you'll need to use desoldering braid or a desoldering pump to remove excess solder. These are extra tools that allow you to remove molten solder.
Another problem are disturbed joints where the solder was moved or vibrated while cooling. Apply heat to remelt the solder and avoid disturbing the joint while it cools.
Soldering is a useful skill which I aspire to learn. But, my experience with soldering has been discouraging. I've spent time trying to learn about soldering. But then that knowledge doesn't match up with my experience, or key details are missing or glossed over. And I appear to be disadvantaged by poor tools and training.
In my situation, I think I should set my expectations low and not expect to master soldering from books. I think I can get my projects to work. But, the process won't be as pretty as the ideal in my mind.
This is important because I think it is better to cope with setbacks and to make progress than to be permanently discouraged by conflicting information and poor results.
In the end, I got my project working. And that's more meaningful than trying to figure out all the ways in which things aren't working.
Soldering Iron Maintenance | HAKKO Corporation
Soldering Iron and Tip Care | Inland | PDF
Are Soldering Iron Tips Universal? | NerdyTechy
Cold and Dry Solder Joints | OurPCB
How To Solder: A Complete Beginners Guide | Makerspaces.com
Soldering Basics | Circuit Technology Center
Everything You Need to Know About Soldering Iron Tips | Scanditronic
Nelson, David Erik. Soldering. 21st Century Skills Innovation Library: Makers as Innovators, hoopla Digital, e-book, Cherry Lake Publishing, 2015, www.hoopladigital.com/ebook/soldering-david-erik-nelson/11415522. Accessed 30 May 2024.
Created: Thursday, May 30, 2024
Updated: Thursday, May 30, 2024