| Electronics > Beginners |
| SMD soldering fine pitch |
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| Lusu:
While THT soldering is OK for me, is is possible (within reason) for an SMD soldering noob like me to solder a fine pitch IC like Wiznet W5100 or W5100S? I keep staring at an arduino ethernet shield (W51000) and I don't see any way to solder this by hand without proper tools (microscope, hot air gun etc.) and a ton of SMD soldering experience. I would like to build my own boards (ATMEGA328P +W5100S + lots of other stuff) but while I can use the -PU PDIP version of ATMEGA, there is no real alternative package for W5100S... I can of couse use a pre-made ethernet board, but I want PoE and there sheems to be quite a shortage of those... Edit: Should I use an socket such as one of those https://www.aliexpress.com/w/wholesale-lqfp48-socket.html ? Are those reliable enough for a "permanent" installation or just for brief programing type scenarios? |
| KL27x:
Doesn't really matter how fine the pitch is. A QFP can be soldered to the proper PCB footprint with just an iron. If you're soldering 1 a week/month, a microscope is not really necessary. You can inspect your work with a magnifier or a loupe if you are farsighted. Half the forum probably insists to solder something like this with a needle tip, pin by pin. And using angle hair solder wire. But SMD IC's are all universally designed so they really don't bridge unless you get too much solder on there (can be removed with wick if this happens). As long as the PCB footprint is properly adhered to, you should not have any major problem. You should put plenty of liquid flux on the pads. Most all you have to worry about is making sure the pins line up with the pads after your first tack. Then zip it up by, say, carefully cleaning off the iron tip and putting just a tiny amount of solder on it, then touching it to the pins. Rinse repeat as needed. If the first few pins bridge, just spread it along and it will be fine. (And if not? Again - solderwick will fix anything). You can carefully dab multiple pins at a time then slide out off the pin ends, rather than dragging along the pins, until you feel more comfortable. If you are ham-handed you could bend a pin while drag soldering, and now you have a problem if you ahve already soldered more than one row... it will be hard to remove with just an iron. A conical is not ideal, and you might need to use solderwick, at worst, if you get too much solder on there. But just about any tip can do this. If you wanted to "make a job of it," a largish bevel/hoof or variant of such is pretty much the best. The difference between a good and bad tip for drag soldering: a good tip will be faster at heating the pins, efficiently, it might work with a greater degree of slop without having to get the angle just so, and it will be more forgiving of the amount of solder applied on it. With a conical, you might need to use a tiny bit of solder and reapply that amount for each row of legs. With a "good tip," you might be able to put a bigger dollop on there and drag solder 2-3 of these chips without stopping. A microscope will reduce the eye strain of doing something like this regularly and/or for long stretches. The big problem with designing your own stuff with SMD IC like this is when you make a mistake and have to rework it with bodge wire. But if you're just buying a dev board, you stand a good chance to get it on there fine, as long as you have flux and solderwick. But sure. Buy that chip socket, too, if it strikes your fancy. Let us know how well it works, or doesn't. |
| rbm:
Agree with KL27x. The Wiznet 5100 uses a 0.5mm pin pitch. That is possible to hand solder with moderate care and with your through hole experience you should be fine. Lots of flux as suggested. |
| Lusu:
Thank you for encouraging me. It is just for few ICs/boards, so far I'm at design & prototyping stage and had success with THT version of it and knock-off ethernet shiedls with bodged wires... I will definetely get a better iron and tips, what I have is like a hammer used to brush your hair :) ... But a full SMD rework station with microscope it's a little overkill. I'm not in favor of the socket, because there are diferential pairs going in&out and this calls for trouble... plus, they are huge. I plan to go with the new variant, W5100S... smaller, firmware compatible, still 0.5 mm pitch and better of all, less heat output. |
| TheHolyHorse:
I soldered a LQFP48 a few days ago for the first time ever with no prior experience with smd soldering. The first two rows got a bit messy but the last two was a no problem at all. As people have already mentioned, lots of flux and and make sure you have solder mask between the pads. As long as you have some feeling and don't go butcher on the thing you'll no doubt handle it just fine. :) |
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