What would be a good way to set up a board for soldering of 48-pin QFN package? Is there something special that should be done to allow for hand soldering of such parts (is it even possible?). Could this kind of part be mounted using the toaster oven or with one of those hot air rework units? What do you recommend? If I am designing a board in Eagle, would I use a standard QFN part component or would it be better to use some other layout like vias where the pins are?
TIA,
Doug
You can try to do the toaster oven method, depending on the pitch between the pins on the chip. I know one guy who soldered a 144 pin QFP package, but he does that kind of work at his current job, he told me he used a really fine iron, and a microscope heh.
This is QFN … N meaning no leads … there are no leads sticking out. They are 5mm pitch. I know that 5mm QFP can be hand soldered, but this is trickier because they are basically just contacts on the bottom of the IC.
– Doug
I expect you mean .5mm :)wearable:
This is QFN … N meaning no leads … there are no leads sticking out. They are 5mm pitch. I know that 5mm QFP can be hand soldered, but this is trickier because they are basically just contacts on the bottom of the IC.– Doug
I’m in the process of figuring out how to solder some DFN chips - which are just like QFNs except that they have pins only on two sides. I am probabaly going to get a hot air station to solder them. What you can do though, if you are feeling adventurous, is to make the pads on the PCB long enough that they stick out past the QFN chip and then you can heat up each pad individually.
I meant to say .5mm yes :lol:
I am pondering the hot air idea also, would that be done with solder paste?
Yes.wearable:
I meant to say .5mm yes :lol:I am pondering the hot air idea also, would that be done with solder paste?
I must admit though - I’ve never done it myself - I’ve just been recently looking into it.
it is possible.
If you extend the leads past the end of the package by 2 or 3mm (enough for a tip + solder) u might be able to do it buy putting a small amount of solder on every pad before you place the components and then getting all the pads hot enough to melt all the solder at the same time.
Gonna be difficult tho.
Perhaps you could try using via’s at every pad an ‘fill’ a via to solder it? lol. might not work.
are TQFP’s a possbile package? for them u just put solder on one pin and place the componenet, head that solder and line it up. The on the opposite side flood it with solder and then heat up 2 or 3 pins worth of solder and sucker it away ;).
I have soldered several QFN packages using FLUX and a flat solder tip. Soldering this kind of devices using flux is pretty fast and easy when you get used to it.
…u might be able to do it buy putting a small amount of solder on every pad before you place the components and then getting all the pads hot enough to melt all the solder at the same time.
I have done this with the ADXL320, a LFCS 16 package, in a toaster oven. I put a SMALL bit of solder on each pad on the board (SFE’s ADXL breakout board), slopped on some flux and cooked it. The package centered when the solder reached liquidous temp (I followed the recommended reflow profile as close as possible by hand) and it works great.
I don’t think it is “precisely” level, but good enough for my (hobby) purposes.
I just did this a couple of days ago.
Use a 22 gauge syringe to put down solder paste on easy side, wipe off about half of it, place the component, then use a hot-air gun to solder it. The solder paste is very visible at the edges of the chip so you can see when it melts.
No worries. 
What exactly is a hot air gun? Is that like what is used for shrinkwrapping? What kind of solder paste did you use?m:
I just did this a couple of days ago.Use a 22 gauge syringe to put down solder paste on easy side, wipe off about half of it, place the component, then use a hot-air gun to solder it. The solder paste is very visible at the edges of the chip so you can see when it melts.
No worries.
Is LQFP possible with SparkFun’s soldering iron station? A hot-air gun would be so much easier but are a little pricey for me. 
TSPRAP:
Is LQFP possible with SparkFun’s soldering iron station? A hot-air gun would be so much easier but are a little pricey for me.
Professional solderers tell me that QFP can be easily soldered manually, by applying flux and swiping the iron across the leads. They do not attempt to solder each lead, instead a motion across the leads apparently works. So I think the answer is yes, QFP can be soldered with an iron.
wearable:
TSPRAP:
Is LQFP possible with SparkFun’s soldering iron station? A hot-air gun would be so much easier but are a little pricey for me.Professional solderers tell me that QFP can be easily soldered manually, by applying flux and swiping the iron across the leads. They do not attempt to solder each lead, instead a motion across the leads apparently works. So I think the answer is yes, QFP can be soldered with an iron.
and that would be with solder paste?
just curious;
What does the L in LQFP stand for?
No solder paste, just flux. L means low profile (height).
and don’t forget solder wick to clean up the bridges.
I just did the following with a 28-pin QFN:
The PCB must have copper on the opposite side of where the chip is going to be. Put solder on each pad where the chip is going to lie on. Don’t skimp on it, you need a decent amount (but don’t overlap, just don’t put too little). Then get solder flux and smear it all over the pads, a pretty decent amount of this too. Put the chip on top and then use a large-tip soldering iron to heat up the copper on the opposite side of the chip. Keep the soldering iron there and after a while the solder will start melting onto the chip. At some point when it’s hot enough the chip will suddenly fall flat onto the pcb and a little solder will probably stick out the sides, this is ok. The chip should now be soldered on. The solder flux helps a lot, you could probably do it without but it wouldn’t be a good contact.
wearable:
No solder paste, just flux. L means low profile (height).
Do I use ANY solder (regular) or JUST flux. Sorry for alll the questions i’m use to thru-hole and the first surface mount chip that I need to use is tight spacing and expensive (would it be hard to remove if I messed-up?)
It would be nice if sparkfun sold solder paste, flux…
wearable:
TSPRAP:
Is LQFP possible with SparkFun’s soldering iron station? A hot-air gun would be so much easier but are a little pricey for me.Professional solderers tell me that QFP can be easily soldered manually, by applying flux and swiping the iron across the leads. They do not attempt to solder each lead, instead a motion across the leads apparently works. So I think the answer is yes, QFP can be soldered with an iron.
You have described ‘drag soldering’. Metcal makes a special mini-hoof tip for drag-soldering with their MX-500 soldering station (I actually use it with a much cheaper second-hand STSS system). It works very well with 0.5 mm QFP packages, but I haven’t tried it with QFN devices. It ought to work.
Leon
My own two cents:
Assembling proto boards with the CP2102/3 QFN devices - the stencil rarely works. We add what I would call solder balls to the PCB - by taking a little solder on the end of your iron and running hot solder over all the pads, this will in effect add flux to the board, and raise the pads with a hair’s width of solder. Take the QFN device and hold it in place. Use a hot-air gun and heat the whole thing up. The ‘solder balls’ should go molten and the IC should now hold in place.
The great thing about hot air: heat everything up, and once you think the IC is in the right place, push it ever so slightly from one side with a pair of tweezers and then release. The surface tension of the molten solder will pull the IC back into place - centered. Now remove the hot-air and everything should be soldered nicely.
-Nathan