AmScope has 15% off all of their scopes right now. The SM-4B series is a well built IMO. Be sure to add the led ring light.
https://amscope.com/collections/ste...stand_type=Filter_Stand+Type|Boom:+Double+Arm
https://amscope.com/collections/ste...stand_type=Filter_Stand+Type|Boom:+Double+Arm
I have a stereomicroscope I use for soldering SMT parts. As I get older, it seems I use it for more and more stuff! It also is great for pulling out splinters, too.
Regular rosin-core solder works fine for things like R's and C's. For the really small stuff it can be very helpful to use small-gauge solder. Trying to solder an SMT resistor whose pads are the size of a pencil tip isn't going to be easy if you are using solder whose diameter is equal to or greater than the entire resistor. You also can get SMT tweezers designed to grip capacitors and resistors. Their end is curved to make it easier to hold them in place while you solder them down. I have a couple with different angled ends if I need to accommodate adjacent (taller) parts. But on that subject: solder the shorter parts first before moving on to the tall ones. Whether they're SMT or thru-hole.
Choose a soldering iron tip that's appropriate for the stuff you are soldering.
Another thing that I have found useful is solder flux, when it comes to soldering parts in fine-pitch packages. Dry-soldering can be an exercise in frustration in terms of solder bridges, but applying solder flux beforehand helps confine the solder to regions it can wet. Like the pads/pins you want.
Depending on the package, pre-tinning the leads can be helpful. This is particularly true for QFN packages, where the "pins" only are on the bottom side of the package. BUT the pins usually are exposed on the sides of the package, too.....permitting some in-situ rework if your reflow process isn't all that great. I always pre-tin the SIDES of those pins, just because of that possibility. It's saved my bacon a few times.....
I also have a solder-sucker for situations where I need to remove a lot of solder, or in places where it's difficult to place solder wick. Different sizes of solder wick also can be handy.
Regular rosin-core solder works fine for things like R's and C's. For the really small stuff it can be very helpful to use small-gauge solder. Trying to solder an SMT resistor whose pads are the size of a pencil tip isn't going to be easy if you are using solder whose diameter is equal to or greater than the entire resistor. You also can get SMT tweezers designed to grip capacitors and resistors. Their end is curved to make it easier to hold them in place while you solder them down. I have a couple with different angled ends if I need to accommodate adjacent (taller) parts. But on that subject: solder the shorter parts first before moving on to the tall ones. Whether they're SMT or thru-hole.
Choose a soldering iron tip that's appropriate for the stuff you are soldering.
Another thing that I have found useful is solder flux, when it comes to soldering parts in fine-pitch packages. Dry-soldering can be an exercise in frustration in terms of solder bridges, but applying solder flux beforehand helps confine the solder to regions it can wet. Like the pads/pins you want.
Depending on the package, pre-tinning the leads can be helpful. This is particularly true for QFN packages, where the "pins" only are on the bottom side of the package. BUT the pins usually are exposed on the sides of the package, too.....permitting some in-situ rework if your reflow process isn't all that great. I always pre-tin the SIDES of those pins, just because of that possibility. It's saved my bacon a few times.....
I also have a solder-sucker for situations where I need to remove a lot of solder, or in places where it's difficult to place solder wick. Different sizes of solder wick also can be handy.
I'm trying that practice kit now. Darn, those parts are small! It's not too bad though. The cylindrical diodes are the worst. They keep rolling. I think I just need to find a technique that works for me.
Thus far I've been pre-tinning the pads and tacking them on for SMD stuff. Some of the YouTube videos talk about using paste and a heat station. For those of you that have used a soldering iron and solder wire but have done SMD work with paste and a heat station, which do you prefer and why?
The professionals at my old job would add a small amount of solder to one pad and hand solder the part to it first. This allows it to be placed solidly onto all other pads. This works well for re-soldering a replacement part (remove solder from all but one of the pads first). I do this and I recently bought a rework station and paste. The latter is my preferred method, but I still use the soldering iron as well. The rework station is well made and very useful for removing multi-pin parts: https://www.tequipment.net/Quick/861DW/Desoldering-Equipment/Rework-Stations/
They have sales pretty much all the time. If you miss this sale just wait for the next one.
Tom
I usually hand-solder all my SMD components. I have an AmScope stereomicroscope which helps quite a bit for getting accurate placement. I have some square-tip tweezers specifically designed to hold SMD parts like resistors and capacitors. With parts like R's, C's and individual transistors I pre-tin one of the pads and solder the part down to it, then solder the remaining leads.
Multi-pin SMT devices like opamps can be problematic in terms of solder bridging, but applying solder flux first greatly reduces bridging. Even so, sometimes I have to remove excess solder with some solder-removing braid. With these, I tack down one pin first and then adjust the package so it is aligned with the PCB footprint. I solder down a second pin on an opposite corner of the package and finish soldering the remaining pins. I use no-clean solder flux but usually remove it using isopropyl alcohol and a brush.
I have a cheap toaster oven I bought for doing things like reflow and annealing steel but so far haven't needed to use it for either task. I HAVE used it to regenerate desiccant packages for drying-out my 3D printing filaments.
If doing reflow be sure to pre-dry your IC packages first, if they have been exposed to ambient air for a day or more A several-hour bake at 50C-80C will make sure that your packages don't delaminate due to steam expansion inside your package. The larger the package, the worse the problem. The very worst are packages that have exposed paddles for heat sinking. Like voltage regulator chips. I'm paranoid about this problem because it killed a lot of parts my company was mounting on PCBs. It cost us plenty to figure out what was going on. There are very good reasons why some parts are shipped in sealed packages with a desiccant packet inside......
Also: Ffne-gauge solder wire is really helpful, in terms of using the least-possible amount. The normal stuff is just too big so you end up with too much solder on the tip of your soldering iron -- and solder bridges become much more likely as a result.
Multi-pin SMT devices like opamps can be problematic in terms of solder bridging, but applying solder flux first greatly reduces bridging. Even so, sometimes I have to remove excess solder with some solder-removing braid. With these, I tack down one pin first and then adjust the package so it is aligned with the PCB footprint. I solder down a second pin on an opposite corner of the package and finish soldering the remaining pins. I use no-clean solder flux but usually remove it using isopropyl alcohol and a brush.
I have a cheap toaster oven I bought for doing things like reflow and annealing steel but so far haven't needed to use it for either task. I HAVE used it to regenerate desiccant packages for drying-out my 3D printing filaments.
If doing reflow be sure to pre-dry your IC packages first, if they have been exposed to ambient air for a day or more A several-hour bake at 50C-80C will make sure that your packages don't delaminate due to steam expansion inside your package. The larger the package, the worse the problem. The very worst are packages that have exposed paddles for heat sinking. Like voltage regulator chips. I'm paranoid about this problem because it killed a lot of parts my company was mounting on PCBs. It cost us plenty to figure out what was going on. There are very good reasons why some parts are shipped in sealed packages with a desiccant packet inside......
Also: Ffne-gauge solder wire is really helpful, in terms of using the least-possible amount. The normal stuff is just too big so you end up with too much solder on the tip of your soldering iron -- and solder bridges become much more likely as a result.
I routinely solder SMD components as part of my job as an electrical engineering technician. Here is my advice:
- I agree that a stereo microscope is a good idea. Even if you can solder with only a magnifying glass or with glasses, you'll find it fatiguing. You'll be hunched over your bench with your eyes inches from your work inhaling solder fumes. A stereo scope will allow you to sit comfortably upright with plenty of clearance for your tools.
- The microscope you chose is not a good choice because it is monocular. Seeing in 3D is super important. I recommend any of these: https://amscope.com/collections/mic...cular&pf_v_brand=AmScope&sort=price-ascending
- Ring lights work really well. I outfitted every assembly microscope in our lab with this: https://amscope.com/products/led-144w-zk
- Heat wands are the best way to solder multi-pin ICs. But I can't advise you what to get because the one's our lab uses cost about $3000. I know you can spend less, but I have no idea how good they are. And heat wands are best with preheaters. Those are expensive also.
I bought a soldering station combo that has a standard soldering iron and a hot-air gun with a number of different-sized nozzles. Online videos using the hot air system looked pretty good but so far I haven't had a lot of luck with it. I think I've been too conservative in my temperature settings.
I'm wondering if your "heat wand" is the same thing or something different?
The analysis lab I worked in used a digitally-set hot plate and aluminum spacers/conductors to selectively heat the region directly underneath the IC we wanted to remove or re-solder. Re-soldering was interesting because if you did it right the molten solder's surface tension would more-or-less align the part to the PCB footprint. Solder flux was needed to get it to work.
The drawback of this approach was that it was incompatible with PCB designs that had SMT parts on the other side of the board, but that wasn't all that common. We mostly worked on RFIC's and I think designers were concerned about the added impedance introduced by vias (I was when I was designing test boards for those things). A vastly different world compared to audio circuits.....
Yes. We call them heat wands. They really look more like a wand than a gun. And "gun" sounds violent where "wand" is magical!
I, too, work in RF land, where a straight wire is an inductor.
^ +1 I've enjoyed mine. With the variety of tips/nozzles, excellent temperature and air speed ranges, and a flexible hose of 'reasonable' length; I haven't found anything missing.
For the OP - I've seen some excellent advice that I wish I'd read before starting my SMD adventures.
Small additions and my
For larger projects or anything with fairly tight spacing, some paste, a heating plate, and the wand are a must for me. For some reason, I haven't been brave enough to try a true reflow oven or even simulate one with a toaster oven or similar.
If the area around the part is reasonable enough to get a tip into place, I use fine wire and flux vs. hot air and paste. I like the liquid flux vs. the flux paste pens, but I've used both. For a board with only 4 SMD parts, I don't think you'll struggle.
I use an optivisor with DA-10 lens (10 diopter => 3.5X at 4" not 10X) lenses for fine work, and a DA-5 lens (2.5X at 8") for larger work with more space (1206 components, MELF resistors etc.). I use the DA-10 lens with the Optiloupe for all inspection. Age aside, I have fairly terrible vision and being able to wear my prescription lenses comfortably under the visor was a must. I find the optics excellent. I have good lighting at my bench, so I haven't had the need for the light kit.
The only thing I'd add to others' excellent suggestions is that if you choose to use a wand / gun, and if you do start to get into some projects where parts density is a little higher, you may like to have a roll of Kapton (or similar) tape on the bench. Why? If you use a wand/gun and don't populate the full board (or a big segment) all at once, you may want to cover any heat sensitive parts and/or parts you've already soldered before going back with the hot air.
Lastly, I don't think I've seen it mentioned, and it may go without saying, but my preferred sequence for boards with both SMD and through-hole is to place all the SMD components first.
Enjoy!
For the OP - I've seen some excellent advice that I wish I'd read before starting my SMD adventures.
Small additions and my
For larger projects or anything with fairly tight spacing, some paste, a heating plate, and the wand are a must for me. For some reason, I haven't been brave enough to try a true reflow oven or even simulate one with a toaster oven or similar.
If the area around the part is reasonable enough to get a tip into place, I use fine wire and flux vs. hot air and paste. I like the liquid flux vs. the flux paste pens, but I've used both. For a board with only 4 SMD parts, I don't think you'll struggle.
I use an optivisor with DA-10 lens (10 diopter => 3.5X at 4" not 10X) lenses for fine work, and a DA-5 lens (2.5X at 8") for larger work with more space (1206 components, MELF resistors etc.). I use the DA-10 lens with the Optiloupe for all inspection. Age aside, I have fairly terrible vision and being able to wear my prescription lenses comfortably under the visor was a must. I find the optics excellent. I have good lighting at my bench, so I haven't had the need for the light kit.
The only thing I'd add to others' excellent suggestions is that if you choose to use a wand / gun, and if you do start to get into some projects where parts density is a little higher, you may like to have a roll of Kapton (or similar) tape on the bench. Why? If you use a wand/gun and don't populate the full board (or a big segment) all at once, you may want to cover any heat sensitive parts and/or parts you've already soldered before going back with the hot air.
Lastly, I don't think I've seen it mentioned, and it may go without saying, but my preferred sequence for boards with both SMD and through-hole is to place all the SMD components first.
Enjoy!