34 Replies Latest reply on May 9, 2019 6:17 AM by andrewj

    First attempt at SMD soldering

    andrewj

      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

       

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

        • Re: First attempt at SMD soldering
          Fred27

          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.

          10 of 10 people found this helpful
            • Re: First attempt at SMD soldering
              andrewj

              I can do you a photo, I'm not ashamed .  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. 

               

              7 of 7 people found this helpful
                • Re: First attempt at SMD soldering
                  genebren

                  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

                  6 of 6 people found this helpful
                    • Re: First attempt at SMD soldering
                      luislabmo

                      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.

                      Luis

                      6 of 6 people found this helpful
                        • Re: First attempt at SMD soldering
                          shabaz

                          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.

                          • Re: First attempt at SMD soldering
                            andrewj

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

                              • Re: First attempt at SMD soldering
                                luislabmo

                                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

                                5 of 5 people found this helpful
                                  • Re: First attempt at SMD soldering
                                    andrewj

                                    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

                                    1 of 1 people found this helpful
                            • Re: First attempt at SMD soldering
                              14rhb

                              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

                              6 of 6 people found this helpful
                                • Re: First attempt at SMD soldering
                                  andrewj

                                  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!

                            • Re: First attempt at SMD soldering
                              14rhb

                              Hi Andrew,

                               

                              Well done for your exploits into the SMT field - I'm sure in time you'll get more confident and start to expand on your equipment required to make things a bit easier (like David suggests a microscope). To answer your questions:

                               

                                   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.

                                   Not in my opinion, but it will cause the tip to deteriorate quicker....not that you'll probably notice much if you only solder occasionally.

                               

                                   2.     Would I fair better with a thinner tip? 

                                   Always handy to make sure you only get the heat onto the required pad, in which case keeping the tip temperature up is probably a good thing.

                               

                                   3.     I used flux but my experience was it burnt off immediately and seemed to do nothing - related to questions 1 and 2?

                                   A flux pen does definitely help the solder flow; it cleans off impurities and helps prevent solder bridging between tracks.

                               

                              I find the best way to solder the smallest resistors is to:

                              • apply flux to the pads
                              • heat and apply the slightest dab of solder (a thin solder wire helps here)
                              • if too much solder is applied then use de-soldering braid to remove the excess
                              • holding the components on the long sides with some fine tweezers, position with one hand and heat the pre-tinned pad to make the initial solder joint
                              • I then use the tweezers to push lightly on the top of the component and reheat that first joint to get the component to sit down flush onto the pad
                              • I then apply solder to the second end
                              • Once that has solidified I often give the first side another quick touch of the soldering iron to ensure a better joint

                               

                              As you have found, it can still go wrong: the tweezers ping the component off to oblivion, the 0603 gets wicked into the solder on the end of your iron, solder bridges remain hidden....all part of the fun

                               

                              Rod

                              9 of 9 people found this helpful
                                • Re: First attempt at SMD soldering
                                  andrewj

                                  All those things happened Rod! 

                                   

                                  The approach you you laid out is, essentially, what I did except the 5th bullet (press on top), I shall remember that.  I did use a flux pen but it just seemed to burn off immediately.  I also think I could do with some thinner solder which is a shame as it isn’t cheap.

                                   

                                  if I give it another go (get another practice kit), I may try a smaller tip and experiment with the temperature.  If only it was as easy as they make it look on YouTube

                                  • Re: First attempt at SMD soldering
                                    genebren

                                    Rod,

                                     

                                    I would second all of your suggestions (almost like you looked over my shoulder when I was soldering.

                                     

                                    Gene

                                    4 of 4 people found this helpful
                                  • Re: First attempt at SMD soldering
                                    shabaz

                                    Hi Andrew,

                                     

                                    That's a good first attempt! I agree with the comments from everyone too. By the way it's almost inevitable that there will be a lot of solder on each component with 0.46mm solder, incidentally that's the thickest size I own too. It's pricey, but this 0.274mm really helps with 0603 and 0402: https://cpc.farnell.com/omega/62s-32swg-lr-250g/omega-62s-low-res-1-250g-32swg/dp/SD00160 otherwise 0.38mm solder is ok for 0603.

                                    350 degrees with your 1.2mm tip sounds reasonable but depends on the iron power. I use a similar ballpark with leaded solder, about 330 degrees C, with a 1mm tip (slice off conical tip) for nearly all SMD work.

                                    7 of 7 people found this helpful
                                      • Re: First attempt at SMD soldering
                                        andrewj

                                        I think I will have to invest in some of that as well.  I have a Hakko Fx-888D with official tips, but the smallest chisel tip is 1.2mm.  I’ll look for someone a smidgen smaller.

                                         

                                        I’m sort of geared up for another try now after all these comments.  This is a great site.

                                          • Re: First attempt at SMD soldering
                                            tooki

                                            The IMHO, smaller tips are rarely helpful for improving SMD. Instead, invest in:

                                            • Thinner solder (0.02”ish happens to be the sweet spot for me) of high quality, like Multicore/Loctite/Stannol or Kester, so that you can feed solder in a more controlled fashion.
                                            • Good paste flux (I use the no-clean paste flux from MG Chemicals)
                                            • A drag soldering tip

                                             

                                            What’s the latter, you ask? It’s a bevel tip with a hollowed out, concave face that holds onto solder. So it actually drags away excess solder from the joint. If you were going to spend money on a tip, I’d get one of these instead. I use one and it’s great for this kind of thing. (Also, I’ve found it handy for other non-SMD uses, like tinning thin wire, or cleaning up some through-hole stuff.)

                                             

                                            Now, Hakko doesn’t officially make one in the T18 series your FX888 uses. But on this discussion, people say that the ones in the 900M series fit anyway (in which case I’d get the 3mm one, the 900M-T-3CM900M-T-3CM Shape-3C), and there’s a reputable third party that makes compatible tips (the “SMD flow” tips).

                                             

                                            I also highly recommend watching some videos on how to solder SMD, namely those from EEVblog (episodes 186, 434, and 997) and John Gammell. (Don’t bother looking at any other YouTube videos on SMD soldering; none come even close to these, regardless of video production quality. Too many show awful technique.)

                                             

                                             

                                            As for your questions, I’d go down with the tip temperature a bit. This will slow oxidation and give you more time to work before the flux burns off. Once you’re more experienced with SMD, you won’t need as long and this won’t matter as much.

                                             

                                            Use good tweezers and keep them clean. SMD components weigh so little that just a bit of sticky flux can grab your component away.

                                             

                                            Use good light and magnification. You will be shocked at how much less your hands shake when using magnification.

                                             

                                            Go lighter on the solder. As others have said, your first attempt wasn’t actually too bad. The positioning is ok for a first try. The biggest thing I observe is just way too much solder on the joints. The videos I linked to show what good joints should look like. (The Gammell ones are gold standard.)

                                             

                                            I’d suggest getting some SMD LED clock kits on eBay/Banggood/AliExpress for practice. Look for “DIY LED clock  kit DS3231” (that’s the model number of an accurate clock chip used in the good kits) and choose ones that use a bunch of SMD LEDs. At $7-20 a pop, depending on how fancy a model, they’re cheap practice, fun to build, and produce something you might actually use in the end! I have a few around the house now.

                                             

                                            Good luck! You’ll get comfortable with SMD in no time!

                                            6 of 6 people found this helpful
                                              • Re: First attempt at SMD soldering
                                                andrewj

                                                Thanks Antonio.

                                                 

                                                I’ve got the thinner solder on order and will pick up a tip as you suggest.  I was also, this month, going to acquire a microscope and another kit to give it a go, specifically with solder paste (also on order) and a lower temperature: my latest project I’ve designed with mostly SMD components so want to get more practice in.

                                                 

                                                Thanks

                                                 

                                                Andrew

                                                  • Re: First attempt at SMD soldering
                                                    Jan Cumps

                                                    andrewj  wrote:

                                                     

                                                    Thanks Antonio.

                                                     

                                                    ....  I was also, this month, going to acquire a microscope ...

                                                    One could also keep on practicing with the bigger SMD parts (e.g.: 1206), where you don't need a microscope. It will help you to fully get the hang of it without frustration.

                                                    And then invest in a microscope ... ?

                                                     

                                                    I learned more from doing SMD soldering often (very often) than from using smaller parts.

                                                    1 of 1 people found this helpful
                                            • Re: First attempt at SMD soldering
                                              fmilburn

                                              Hi Andrew,

                                               

                                              I will chime in with everyone else.  It looks quite good.  I am pretty new to SMD soldering myself but I can promise you will get better, it just takes practice.  Like you, 0805 is what I feel comfortable with manually soldering although I can go 0603 in a pinch.  Kind of repeating what others have said but try some flux on the pads especially with cheap PCBs.   I use 0.3 mm rosin core solder.  My technique is very similar to 14rhb.  Sometimes I use solder paste instead of solder with an iron and that works too.  Great start!  I actually prefer SMD to through hole now if the parts are 0805 or larger.

                                              5 of 5 people found this helpful
                                                • Re: First attempt at SMD soldering
                                                  andrewj

                                                  Thanks Frank. 

                                                   

                                                  Actually, I might try solder paste - that seems like it might be a good start with tinning the first pad.  I did that with the solder but it wasn't easy - I could actually use my magnifying glass with paste.  Clearly I need to work with the flux more because that just didn't seem to help.  It is MG Chemicals as well, so not a bad brand.

                                                    • Re: First attempt at SMD soldering
                                                      Jan Cumps

                                                      If you tin all pads first, they become wobbly. It is then hard to keep your component in place.

                                                      Tinning one pad of each component, and use that pad as the first one to solder, is an option.

                                                      Push the component down with something (I use a pincet), then heat that single pre-tinned path.

                                                      Your component can now no longer run away and you can solder the remaining pads.

                                                       

                                                      Don’t go easy on the flux. I use a lot.

                                                      6 of 6 people found this helpful
                                                      • Re: First attempt at SMD soldering
                                                        14rhb

                                                        I've never used solder paste either (perhaps I should give it a go?) but I am aware it has a shelf life of typically 3-6 months at room temperatures. I'm not sure what happens to it after that and whether you can still use it. Maybe it dries into a solid block in time so you cannot get it out of the syringe.

                                                         

                                                        Rod

                                                          • Re: First attempt at SMD soldering
                                                            andrewj

                                                            As I understand it, it does have a shelf life - people seem to keep it in the fridge.  I read somewhere it goes off because of the IPA in it but I haven't really looked into it; I've also read that people have re-activated it by mixing IPA back into it but who knows. 

                                                             

                                                            You can buy it in tins as well as syringes - I guess it would depend on the amount you used as to what you got.  Anecdotally, I've read that syringes can be awkward as it tends to drag it around, but again I have no experience - I expect it's like all the other YouTube videos where people make it look dead easy!  With a tin, you could use a cocktail stick or craft knife.  I suppose you could syringe a blob out and then apply it the same way.

                                                             

                                                            Anyway, I guess if you never try it, you'll never know; it's always a learning experience

                                                            2 of 2 people found this helpful
                                                            • Re: First attempt at SMD soldering
                                                              fmilburn

                                                              I am no expert but have kept it in use for up to about a year at room temperature.  The problem is that it dries out and becomes hard to apply with time even though the joints look OK.  I had one syringe where I noticed separation after a year or so.  Note that this is my hobby, not for commercial use. I have always bought it in a syringe.  I usually squirt some out until it looks fresh and then apply it with a plastic toothpick if not using a stencil. I have a friend who always uses stencils and buys it in small tins. He has also kept it in use up for a year or so.  I keep it sealed up tight by capping the syringe and then putting it in a sealed plastic bag with air expelled.

                                                              4 of 4 people found this helpful
                                                        • Re: First attempt at SMD soldering
                                                          jw0752

                                                          Hi Andrew,

                                                          I think you did a pretty good job too. With respect to the LEDs I always use a small analog multimeter set to R X 1 to test and verify polarity on small difficult LEDs. In the case of my analog meter I have tested it and I know that when it is on Ohms scale the black lead is positive and the red lead is negative. Here is a picture of the polarity test of a small SMD LED. The only trick is, once identified, not loosing the orientation on the way to the board. You should be able to test and verify the polarity of your LEDs using the same trick as the test usually works very well even for LEDs that are mounted and in circuit.The procedure doesn't work with digital auto ranging meters just the cheap analog meters that use (2) AA batteries for the Ohm ranges.

                                                           

                                                           

                                                          John

                                                          10 of 10 people found this helpful
                                                          • Re: First attempt at SMD soldering
                                                            colporteur

                                                            Are you able to share the product name and number for the kit?

                                                             

                                                            What did it contain or not contain you would recommend in a practice kit?

                                                             

                                                            My solder skills were developed well over 35 years ago. I never had the opportunity to work in SMD. I recently purchased a ruler guide to help me understand terminology. Using the ruler made it easy for me to follow the discussion.

                                                             

                                                            Sean

                                                              • Re: First attempt at SMD soldering
                                                                andrewj

                                                                Hi Sean,

                                                                 

                                                                if you search on Amazon for 'SMD practice kit' you get loads of hits (co.uk and .com sites) so take your pick.  I'm not sure I can recommend any one over the other as I suspect they are pretty much all much-of-a-muchness.  If I was doing it again, which I might, I'd avoid the ones with anything smaller than 0603 (on the other hand, it's just practice so what's the worst that can happen??)  You'll have read the comments above, all of which are essential-to-very-useful to take on board.  You will need a magnifying glass minimum but it's a bit hit or miss as you can use it to line things up, but need to put it down to actually solder!  A microscope or at least some form of hands-free magnification would be useful - given the price, I won't buy a microscope for a kit but will do when I get around to my project which I'll probably use SMD parts for.

                                                                 

                                                                Sorry, to specifically answer your question: it contained components that could be soldered with an iron, i.e. no hidden pads like a QFN package.  The smallest component was 0603 which I didn't particularly like, but it's practice so you may feel differently.  You'd want something with one or two ICs in it as well.  There are some that might produce something useful, like light up icicles for christmas decorations but these seem to be a little expensive.  I wouldn't worry too much about Chinese-only instructions as there should be a schematic and at least a list of the components and sizes, but you will need to do some figuring out.

                                                                 

                                                                Hope that helps and good luck.