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First attempt at SMD soldering

Andrew J

I bought a practice kit that, in theory at least, lights up LEDs in some sequence.  I say in theory, but as all the instructions (presumably) are in Chinese, who knows??  Anyway, it has components in a number of sizes: 1206, 0805, 0603, 3528, not sure for the ICs.

 

I've spent the afternoon soldering away - 76 components - and what can I take away from the experience?  Well:

  1. forget 0603, I'm not going there again.  Just too small for hand soldering.  I did of course lose a 0603 capacitor to the God of Misery and the kit had no spares.  One day, I expect to find it. Or not.
  2. forget resistor arrays as well (I think that's what they are), especially in 0603.  Seriously, what sadist invents such a thing??
  3. 0805 is likely to be the minimum I go with.
  4. I need a microscope to do this stuff.  At my age, my eyes aren't good enough and I have a bit of handshake too.  See also (1)!
  5. I need more practice at (a) soldering; and (b) keeping care of my tip.
  6. 0.46mm solder is still a bit thick, but just about do-able.  I dare say if I was better at 5a then it would be ok
  7. Still unsure of the best tip to use.  I had a 1.2mm chisel tip which is the smallest that I have, bar a pointy one
  8. Solder wick (decent stuff) is very useful
  9. It's not clear what the markings on a LED are - there were two variants (green marks on one lot, cut corner on the other lot.)  I did search but found the information results confusing: I assumed the marks referred to the Cathode.
  10. The ICs weren't too bad: I can't detect bridging, solder wick helped
  11. I don't think I'd be too worried about it in the future, at least I've taken the plunge right!  I'm not convinced I'd do better with paste and a hot-air gun either.

 

Questions I have:

  1. Is 350c too hot?  I used leaded solder: Sn 62, Pb 36, 2Ag with 505 rosin cores from Multicore.  It has a melting temperature of 179C.
  2. Would I fair better with a thinner tip?
  3. I used flux but my experience was it burnt off immediately and seemed to do nothing - related to questions 1 and 2?

 

I suppose the question on everyone's lips is "did it do anything?"  Well, in short, no.  I tested the resistors and they seemed ok, the ICs were getting voltage to the correct pins so I know they are the right way around.  Perhaps the LEDs are on the wrong way, perhaps the soldering isn't right, perhaps components are not in the right place (no markings on the tapes so I may have deduced incorrectly), perhaps it doesn't do anything anyway, perhaps, perhaps.  I'm not too bothered: it was a test/practice of soldering SMDs which it achieved.

 

I could definitely do with more practice but I expect I'll get better over time.  I also think that these practice kits are a good idea and I would recommend one to someone whose not done this before.

 

Thanks for listening image

 

EDIT: I have a follow up thread as well - https://www.element14.com/community/message/275494/l/second-attempt-at-smd-soldering#275494

Parents

  • No photos? Maybe best not for your first attempt! Of course you can now practice some rework until either the LEDs light up or you destroy it by lifting a track. It won't take long to get used to SMD. I must admit I was scared at first but soon found I prefer it to through hole - at least until I get to QFN packages!

     

    I can thoroughly recommend a microscope. I went with a non-branded eBay version of the usual Amscope one and I'm glad I did. Review here if you're interested.

     

    Solder paste and hot air is definitely your friend if you're planning on more SMD work. I've also found that the low end (Yihua 898D+ in my case) does a reasonable job for without spending loads on something you're not sure you'll need yet.

  • in reply to Fred27

    I can do you a photo, I'm not ashamed image.  Don't look too closely at the Capacitors though - those were (some of) the evil 0603s, one of which has gone on holiday.  This was all done by eyesight as well. 

     

    image

Reply Children
  • in reply to Andrew J

    Andrew,

     

    If you did the above work with eyesight (no magnification) then your vision is not too bad (I don't think that I could that well without my microscope).  David is right, a microscope (even a relatively cheap one) is the way to go.  I bought mine, used, off of ebay and I have not looked back.  Also, with a microscope, good lighting is very important (I ended up building my own light ring, but before that I used a halogen desk lamp).

     

    Practice makes perfect, or at least better.  I find that 0603 is doable, but 0402 was absolutely crazy (I could do it, but it was not always pretty).

     

    Well done and good luck on your future attempts.

     

    Gene

  • in reply to Andrew J

    Wow, are you sure this is your first go at SMT? It is really good.

     

    Sometimes a dab of flux on the couple of ragged joints and a quick touch of the soldering iron and they pull back into a nice 'wetted' joint. Sometimes it is possible to burn the flux/rosin and with other board contamination you end up with a horrible joint that never seems to want to take solder properly. The small brass brush or fibreglass cleaning pens plus some Isopropyl Alcohol help clean the area up for a new attempt (some of the joints along the top edge may have gone down that route ? ).

     

    Rod

  • in reply to 14rhb

    Thanks for the encouragement, appreciate it.

     

    I’ll remember you’re point about flux touch up.  I struggled with it to be honest as it didn’t seem to help - everything I saw on YouTube showed it ‘flowing into place’ but I just didn’t find that.  I expect I just need more practice and a better view of what I’m doing!

  • in reply to genebren

    I think a microscope for this kind of job is an excellent idea -or any sort of magnification-. I personally use a head magnifier which is a good and cheap starting point before investing in a microscope.

    image

    Luis

  • in reply to luislabmo

    Nice looking magnifier : ) I hope to try a head-mounted unit sometime.

    Despite having an old microscope, and camera, I still sometimes like just to use a small magnifier lying around on the desk for inspection, simply because that is within easy reach.

    I now have a nicer glass lens, but for its low price this plastic ultra optix magnifier with LED is surprisingly good, I've had it for years.

  • in reply to luislabmo

    I’ll give one of those a go Luis.  What sort of magnification do you use and how close do you end up getting?

  • in reply to Andrew J

    Hello Andrew,

     

    In short, I use the maximum stereo-lens magnification combination when inspecting my solder joints or when I need to find/verify the SMT components marks and I use the lowest stereo-lens magnification when applying my solder paste (I do it with a syringe) or when hand soldering SMT. Distance is about 10in for the lowest magnification and 5in for the highest  -from surface in focus to my face-.

     

    I currently own these, there is a magnification combination you can check there:

    • 1.9X (the fixed 1.9X stereo lens alone).
    • 3.8X (two 1.9 stereo lenses combined).
    • 6.4X (fixed 1.9 lens with 4.5X loupe).
    • 8.3X (both 1.9X lenses with 4.5X loupe).

     

    Luis

  • in reply to luislabmo

    Thanks Luis.  I purchased a (different) set with glass lenses to give it a go: 1.5x, 2x, 2.5x, 3.5x.  My first impression is that I would want the 3.5x to actually hand solder SMD but that gives me about 5" or so from my nose to the board; also it feels like a minimum magnification I would need.  2x and 2.5x gives a bit more room but the magnification isn't good enough.  In all cases I was hunched over and could see that being uncomfortable.  I've also got another test soldering kit to give it a go so I'll work out some way of raising the soldering surface and see how I get on.  On the plus side, it felt comfortable to wear and I could keep my glasses on.  It was also about 10% the price of a microscope so that's a bonus.  Even if I can't get on with it for actual soldering it will definitely be useful for inspecting etc.

     

    Andrew