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Is soldering by hand still needed?

I’ll confess: I really enjoy making a well-crafted solder join between two wires or soldering a component onto a PC board. There’s something very satisfying about the smell of the rosin (we won’t talk about the lead fumes, of course) and the crisp eutectic transition of the solder between its solid and liquid states at 183 o C (for tin 63% /lead 37% solder), Figure 1 , and the shiny end-product of the well-formed connection.

Figure 1

A eutectic material goes from solid to liquid phase and reverse without an intermediate 'plastic' state; for solder, the eutectic formula is a composition of 63% tin and 37% lead. (Image source: FCT Solder)

A eutectic material goes from solid to liquid phase and reverse without an intermediate “plastic” state; for solder, the eutectic formula is a composition of 63% tin and 37% lead. (Image source: FCT Solder)

Being able to solder in various situations has saved me in tough spots many times, such as when doing a smart-thermostat installation (see Simple Schematic, Challenging Installation) or replacing a $3 failed capacitor in a $50 TV-converter box. Way back in the day, soldering even let me build all sorts of experimental circuits with discrete transistors, passive components, switches, and more, and these circuits were both reliable (if soldered well) and low cost (no prototyping board needed).

But I am also a realist: that was then, while this is now. I don’t see much need or opportunity for basic soldering for students, advanced hobbyists, or even project engineers. Let’s face it: most components are too small to solder (yes, I know it can be done in some cases with a fine-tipped iron, good eyes, steady eyes, and a magnifier, but still…) and many ICs simply can’t be hand-soldered due to connection bumps that are under their packages. It is possible to convert a toaster oven into a home wave-solder machine – lots of web sites show how – but that’s another soldering story altogether. Even analog sensors and specialty components now often come complete with miniature connectors thus eliminating the need to solder leads, and have you ever tried to solder those hair-thin wires used in earbuds when trying to replace a bad connector?

That’s why I was truly surprised, pleased, and slightly mystified to see the sign of Figure 2 outside our local library. I’m not sure if soldering is a skill for 10-year-olds, but maybe it’s at least OK to get them started. Unfortunately, I was not able to drop in and see what the class was actually like, how it was taught, and if the basics were being presented properly.

Figure 2

This library sign advertising a soldering class for 10-year-olds was definitely not expected. (Image source: author)

This library sign advertising a soldering class for 10-year-olds was definitely not expected. (Image source: author)

Coincidentally, a few weeks after I saw that sign, there was a very brief one-column piece “How to Use a Soldering Iron” in the April 2019 issue of Popular Mechanics (scanned as Figure 3 ).

Figure 3

This column from Popular Mechanics is mistitled; it should be 'How NOT to Solder.' (Image source: Hearst Corp./Popular Mechanics)

This column from Popular Mechanics is mistitled; it should be “How NOT to Solder.” (Image source: Hearst Corp./Popular Mechanics)

Hey, I thought, perhaps the “maker” movement is helping basic wire and board soldering make a comeback. But when I read the column, I was shocked. It would have been better if it were placed in the “what’s wrong with this picture?” item which was on the back page of that same issue. Look at the column and review the oversights and outright mistakes:

  • no mention of use of rosin flux (yes) versus acid flux (a big no-no);
  • no mention of use of rosin-core solder which applies just the right amount of flux, rather than brushed-on paste. Most beginners who use paste flux use too much, which then interferes with the soldering process and also becomes a mess to clean off;
  • never use sandpaper to clean and prep the iron’s tip; most tips are plated to improve “wetting” of the solder with the tip. It’s like cleaning tarnished silver-plate utensils with sandpaper;
  • no mention of the need for cleaning any residue, oil, varnish, or other substances from the wires being soldered (very important!);
  • perhaps most worrisome: while it is unclearly written, it implies that you heat the solder until melts, and let it drip onto the wires. That’s the classic recipe for a cold-solder joint which is both mechanically and electrically unsound. (Best is to heat the bare joint you are making, apply the solder to the other side, and let the heated joint melt the solder);

Pretty much the only point that is right in this column is the warning to be careful, as the iron will be hot.

What puzzles me is that even if the anonymous author commissioned to do the article didn’t know anything about soldering, he or she could do a web search on “How to Solder Wires” and tens of credible sites would pop up with detailed text and hands-on videos. It’s almost as if the author just imagined soldering as an abstract construct.

Do you still see a need for hand-soldering skills? To what extent? Has your ability to properly solder wires and PC-board components (assuming you can) ever been a real plus, either personally or professionally?

Also of interest

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Analog Circuits Give Boost to STEM Reality

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Product Review: Weller LED soldering iron

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6 comments on “Is soldering by hand still needed?

  1. MWagner_MA
    March 27, 2019

    Bill I have to assume you were just “baiting” us EE's with this article 🙂  Yes, hand soldering is still needed in the professional realm.  If you are building prototypes (like I am now for an intrinsic safety product), and using TO-220 pkgs, yes.  Pkgs like this take up less board space than the equivalent SMT device with its requisite copper area.  I agree some processor projects are too small a pitch to hand solder, but for power devices, we'll need it for the forseeable future, especially for small batch prototypes.

  2. DaveR1234
    March 27, 2019

    Absolutely hand soldering is still needed.  In fact I just ran into a most unusual problem.  I had a Kitchen Aid food mixer that didn't work.  I found it had a failed MOV (blown to smithereens) on the PCB and assumed there was a voltage transient so I replaced the TO220 Triac.  Further debugging discovered the 5 volt supply for the uP was 0 volts, so I spent many hours tracing out the circuit to hopefully find the failed component(s).  I never did figure out how the 5 volts was derived (anyone with a clue, please post a schematic and explanation), but discovered that there was no continuity between the leaded switch and the PCB traces it was soldered to.  The solder fillets looked OK, but I thought I'd reflow them to be sure.  Still no continuity.  I had to scrape away the solder mask around each pad so I could get a connection between the switch lead and the copper trace.  Apparently the transient fractured a ring around the existing solder pad resulting in the open circuit.  I guess if you live long enough you see everything.  To see the PCB go to:

    https://www.youtube.com/watch?v=qxA6qSOXgXI

  3. Bill_Jaffa
    March 27, 2019

    No, I am NOT baiting–and yes yo do have a point. But I have met a surprising number of circuit EEs (not software types) in the last few years who have never soldered (or have done it once or twice, were not sure what they were doing, but “it worked” so they moved ahead) –and they are gainfully employed. That's why I raised the question, I suspect only a modest subset of EEs (mostly powe & analog) do soldering anymore as part of the job, or they call a “tech” in to do it!

  4. MWagner_MA
    March 27, 2019

    The problem you will see is there will likely not be “Tech's” any more as they are not respected nor paid well.  I started out as a “tech” and a good friend is one and struggling as the industry doesn't think what they do requires skills.  Its ok if everyone goes “hands off” the hardware.  It will insure I have a job until retirement :-).  Thanks for the article – get's people thinking.

  5. raj_at_anasim_dot_com
    March 27, 2019

    A parallel to what you ask, @Bill_Jaffa, can be the question: “Is handwriting skill important, anymore, in these days of omnipresent printed documents?” The initial two days of my first industrial job as an electronics line supervisor were spent – wholly – on soldering and desoldering all sorts of electrical interconnections. Thin traces, thick traces, through-holes, pads, connectors, wires, …I learnt enough to be able to communicate sensibly with the more experienced (and skilled, likely) line personnel. The fine motor control, the details of the process, the quality of a good handmade electrical joint, the artistic skill…I think there's so much one gains from doing this specific activity that could reflect on one's whole work philosophy. Just as one applies Graphology (the science of handwriting analysis) to evaluate someone's psychological makeup, I'd go so far as to judge any electrical engineer, in part, by his or her ability to make a good electrical joint! 🙂 

     

  6. MelBrandle
    April 18, 2019

    I think it is indeed still necessary if we wish to create a flawless setup. We know that soldering somehow binds 2 ends together strongly so your setup becomes more durable. It is a simple yet very practical way to make our products last much longer.

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