I need Soldering training

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Gillespie1983, Dec 2, 2017.


  1. HotBluePlates

    HotBluePlates Member

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    As said before, the first thing to do with a new iron is melt plenty of solder on the tip the first time you plug it in. That's "tinning the tip".

    Some Weller irons used to have a large copper tip with a tinned coating. If you had one of those you could file the oxidation off, get back to bare copper, and tin the tip again. But most often, you can't file tips and must replace them. Wherever you bought the old iron has new tips (last time I bought a Weller was a home improvement store, and they had a package of replacement tips).

    Forget lead-free solder, you want 60/40 as mentioned earlier. Lead-free needs more flux, more heat, and is more hassle if you don't need to meet RoHS regulations.

    If you get flux, get a liquid type. There are flux pens. At one place I worked, we had liquid flux in a small bottle with a needle-tip on the end. Very handy!
     
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  2. viejo

    viejo Member

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    Get some junk electronics take them apart them and then solder them back
     
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  3. Coolidge

    Coolidge Member

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    I emailed this to someone last week who is thinking of building a kit amp...

    Soldering Like a Pro – The trick to soldering like a pro is you go in with a hot iron and punch it right in the face with heat, then quickly pull the iron off. The longer you have to hold the iron on the component leads and turret the more heat rapidly races up the component lead to the resistor or cap, or down the turret to the turret board.

    So an iron that can deliver a lot of heat quickly, check! Next is your technique. Clean your iron tip before each soldering attempt on a wet sponge to wipe off the crud, then dab a bit of fresh solder onto the tip. While the tip is tinned, its this little blob of fresh solder that is the conduit that heat rapidly travels through from the iron to the component lead and turret, bang. Without the little blob of solder it takes much longer to transfer heat from the iron and you end up cooking the component or turret board.
     
  4. zenas

    zenas Member

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    Totally agree with the hot clean iron Coolidge is talking about.
    I don't use an iron nearly much as since I got my uncles vintage Weller gun. Didn't think I'd ever use it but actually love the thing. (no worries about forgetting it plugged in with the trigger) Guns aren't generally recommend for amp work!
    For chassis grounds and cap cans my life got way better after paying 5 bucks for a big old 200 watt iron. It just melts the solder so much faster than the 100 and 80 watters I used to use. And that is key, get it done quick so the heat doesn't spread.
     
  5. wall_of_sleep

    wall_of_sleep Member

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    Just use basic rules.

    -Get the parts to hold themselves together first. If all the mechanical connections were strong enough, we wouldn't even need solder.
    -Melt the solder you're flowing with the parts, not the iron tip.
    -Shiny soldering is good, dull is bad.

    Do yourself a favor and use small diameter with lead.
     
  6. TimmyP

    TimmyP Member

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    With a gun, make sure that the device you are working on is disconnected from the mains - grounding the tip of a gun makes it very unhappy, as I learned about 45 years ago.
     
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  7. zenas

    zenas Member

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    Always good advice to unplug something whilst soldering on it. :)
     
  8. HotBluePlates

    HotBluePlates Member

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    Agreed that you must get a good mechanical connection first. As for holding the connection together, solder does that but also keeps that mechanical connection from oxidizing (and becoming intermittent/failing over time).
     
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  9. TimmyP

    TimmyP Member

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  10. John Coloccia

    John Coloccia Cold Supporting Member

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    Thanks for the plug. I don't pretend that there's just one way to do it, but most of the guys that have slugged their way through my videos come away with at least an idea of what they're trying to achieve, however you get there.

    re: soldering iron watts...

    er...whats? If you want to make soldering easy, forget about soldering "irons" and get a proper solder station. I don't even know what a 15w soldering "iron" means. 15 watts of what? How hot does it get? What's the thermal mass? It's like saying you have a 15w television set. OK...so how loud does it get...how bright? It's a meaningless figure on it's own.

    Something like a Hakko FX-888D with some reasonable tips (conical tips are generally not reasonable). Watts shouldn't = temperature. With a proper station, watts = how big a thing you can solder, and temperature = what you set it to. With cheap soldering irons, all you get is an iron that is too hot to start with, and that cools down too quickly after you touch the part to make a good joint. Yeah, people solder with junk irons, and some people also solder with mini butane torches. I'm just telling you what will make it easy and enjoyable.

    Soldering with decent equipment is easy, and soldering with junk equipment when you're skilled and know what you're doing is doable. Soldering with junk equipment when you're a beginner just winging it will drive crazy. :)
     
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  11. ctreitzell

    ctreitzell Member

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    hmmmmm...I don't see those YT embeds in that thread....will have to dig deeper into it
    also, there are a lot of missing photobucket images :-/
     
  12. Jeff Gehring

    Jeff Gehring Silver Supporting Member

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    Just do like this guy...

    [​IMG]
     
  13. Coolidge

    Coolidge Member

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    That is so wrong on so many levels lmao!
     
  14. Kyle B

    Kyle B Supporting Member

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    I don't agree

    Mechanical connection is irrelevant for a good solder joint. The only purpose (IMHO) of seeking a solid mechanical connection first is to keep the parts stationary while the solder cools. If you have any motion during the cooling process, the metal doesn't crystallize properly and you don't get a good intermetallic layer. That said, whenever possible, I do indeed go for a solid mechanical connection first - but if that can't be done, I don't sweat it.

    I'm lead EE in a major consumer electronics company (that shall remain nameless). In the majority of the products we make, the wires are just 'tacked' on the boards... No holes, just a blob of solder keeping the wire down. I'm not talking a few dozen items... i'm talking tens to hundreds of millions of products being soldered either by robots or by very young Asian women, all done with sh*t ROHS solder. If this were an issue, we'd know it. What I do see fail frequently is the wire breaking at the joint because it fatigues, but the joint itself is fine. In fact, can't recall EVER seeing evidence that one of them 'came loose'.


    If you think about ---- The majority of electronic equipment you currently own is chock full of thousands of solder joints that have zero mechanical strength. If you could somehow remove all the solder from this board, what do you think would happen to all the parts??? They'll all fall off first time you touched it, or even breathed on it. (Well, not entirely true... the really tiny ones often get a dab of glue to hold 'em steady during reflow)


    [​IMG]








    One bit of technique almost everybody misses....

    When you are done soldering any given joint, do NOT clean the tip!!!!! Leave the crud on it!!!! That seals the tip and prevents oxidation, making your tips last longer. Further, when you are done soldering for the day, tin the hell out of the tip and then shut off the iron... don't clean it first. The ONLY time you clean the tip is within about 3 seconds of soldering a joint. Do this and your tips will last a very very long time indeed.
     
    Last edited: Jan 17, 2018
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  15. HotBluePlates

    HotBluePlates Member

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    It's been a long time, but I once worked at a p.c. board manufacturer. Which makes it ironic that you had a photo of chips on a p.c. board. Plenty of boards would come from wave soldering, pass a power-on test, then fail on a functional test.

    The problem? A leg on the chip would only be connected to the solder pad by the solder. The fix? Add some flux, heat the leg, press down so the leg firmly contacts the solder pad below.

    My point was never rely on solder to make the electrical connection for you. It will work many times... until it doesn't work & you can't figure out why.

    I'm not suggesting the connection needs strength, only that the best rule is to insure the conductors touch each other and would work in the absence of solder.

    Now, I do know there are times when one can break the rules and form connections with solder bridges, etc. It's just not the place to start for anyone needing to ask about beginning soldering.
     
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  16. Kyle B

    Kyle B Supporting Member

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    With due respect, I'd propose that what you saw was real, but your explanation for the physics behind it are not quite on point. You were probably fixing cold solder joints, or joints that LOOKED like they were 'soldered together' but if examined under high magnification, they weren't . My method of finding bad reflow joints is look at pins with a microscope, and then wiggle them with the tip of an exacto. It becomes really easy to find the bad ones because they break free with little force. Or something else was going on - I wasn't there to view these issues to render a valid opinion. I guess to believe it, I'd have to watch (again, under magnification) a quick touch-up being done to the pin w/o bending it down, have that fail function test, then bend the pin down and reflow again, this time passing the test. And I'd probably need to see that same thing repeated about a dozen times before I buy into it.

    Consider that if what you say were true "A leg on the chip would only be connected to the solder pad by the solder" then the pin would have worked electrically and not required repair because solder is conductive. That you'd need to fix them indicates something else going on. If you could spot these because they're lifted, then perhaps the issue generally was insufficient paste to bridge the gap???

    I believe it's normal actually, that after a reflow, NONE of the components will have their pins touching the PCB. The surface tension of the solder will lift them up and fill the space underneath. BGA's certainly aren't making a positive contact. I mean - How hard could a typical SMT pin be pressing into the substrate??? No way a row of 40 pins are all gonna be so accurately positioned such that every single one makes a positive connection with the PCB.

    Certainly I'd agree forcing a direct connection can't hurt. ;)
     
  17. John Coloccia

    John Coloccia Cold Supporting Member

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    I don't know why it suddenly started doing that. I changed all the links and they're showing up again.
     
  18. John Coloccia

    John Coloccia Cold Supporting Member

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    re: mechanical connections

    No mechanical connection here. Just a good soldered lap joint. I'm REALLY abusing it too...notice how much the cable stretches. BTW, I'm still using that cable as my main cable. My main rule of thumb is if you're worried about it breaking, then you must immobilize it somehow, whether it's a wire, a heavy cap or whatever else. If it can't move, it can't break. The strain relief on the cable does just enough that it keeps the wire from wiggling at the joint. All I can do is pull straight, and it ain't ever going to break like that. If the strain relief wasn't there, the wire would flex at the joint and either fail the joint at the stress riser (and basically peel/crack the solder right off) or the wire itself would break. Once's it's immobilized, it's going NOWHERE. :)

    For through hole, I believe the testing has shown that even an imperfect joint (not a cold joint, but just one that doesn't have 100% fill, nice fillets, etc) is stronger than the substrate. For surface mount, the joint quality is more critical because an imperfect joint is actually quite weak, and stress will easily pop leads off pads. I've also seen SMT joints where it looks like it's making contact, but it's really not. Just a little pressure with a probe suddenly makes the thing work.

    But back to your excellent point, the mechanical connection usually has pretty high resistance when talking about surface mount stuff. The solder is basically making the electrical connection.

    BTW, the wiggle test is a great idea. A tech showed me that some years ago. How much time it would have saved me if I'd known that sooner!

     
    Last edited: Jan 18, 2018
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  19. Kyle B

    Kyle B Supporting Member

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    Thanks brother : )

    When I get some time, I'll have to watch your videos. Sure you'd like me to point out all your errors and inconsistencies... er... I mean see what I can learn from them ;)
     

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