First QFN removal with budget solder Huakko station 998D

[jondoe]

After lots of swearing and practice on scrap boards I've finally managed to remove a QFN IC using my budget Huakko 998D soldering station, without completely destroying it.

I had to crank the temp up to 420 °C, much higher than expected, but she did eventually come free. Judging by the close up attached picture I've slightly lifted one trace in the process and moved a couple of SMD's a little, but I think I could actually use this board again

Practice makes perfect as they say

[diif]

Re: First QFN removal with budget solder Huakko station 998D

Nice job, minimal work required to get those moved components back in place.
I recommend Amtech 559 flux, allows for plenty of reworking before it goes off. Be careful on ebay, there's loads of fakes. Insatint is the genuine seller.

[eccerr0r]

Re: First QFN removal with budget solder Huakko station 998D

speaking of removing SMD components, did you use square attachments or just used a regular circular nozzle?

The best luck I've had in desoldering board is using a heat gun, but it tends to rip off more than just the target device and destroys plastic connectors ...

[jondoe]

Re: First QFN removal with budget solder Huakko station 998D

Nice job, minimal work required to get those moved components back in place.
I recommend Amtech 559 flux, allows for plenty of reworking before it goes off. Be careful on ebay, there's loads of fakes. Insatint is the genuine seller.

I had some very thin watery flux, it wasn't much use. Thanks for the suggestions, I'll be getting some of that tacky Amtech stuff.

speaking of removing SMD components, did you use square attachments or just used a regular circular nozzle?

The best luck I've had in desoldering board is using a heat gun, but it tends to rip off more than just the target device and destroys plastic connectors ...

I used the smallest nozzle in the kit, bog standard kinda thing, quite low air speed (setting 2 of 8), spent plenty of time bringing the board up to temp.

Kapton tape on your plastic connectors should protect them from the worst of the heat.

[diif]

Re: First QFN removal with budget solder Huakko station 998D

I wouldn't worry about warming the board when doing SMD rework. It's only when doing large BGA work does it matter, far more heat needs to be put into a much larger area.
Nozzle up close, little waft for a few seconds and watch as the solder changes through the microscope.

When you say heat gun eccerr0r, do you mean paint stripping gun ?

[eccerr0r]

Re: First QFN removal with budget solder Huakko station 998D

Yes, and yes it has an extremely high chance of destroying the board...

[eccerr0r]

Re: First QFN removal with budget solder Huakko station 998D

BTW, fake rosin...what do you actually get? Is it not so great rosin or something that looks like rosin that doesn't even work like rosin?

[diif]

Re: First QFN removal with budget solder Huakko station 998D

BTW, fake rosin...what do you actually get? Is it not so great rosin or something that looks like rosin that doesn't even work like rosin?

What's fake rosin ? Amtech 559 is rosin based tacky flux that lasts flipping ages when reworking. There's a reason it's more expensive than normal flux.
Comes in a syringe and I stick a needle on it. Super easy to administer.
Being tacky it holds pieces in place. Used for BGA reworking and normal rework.

MG Chemicals also make a tacky flux, some say it lasts longer than 559 but I've no reason to change.

[eccerr0r]

Re: First QFN removal with budget solder Huakko station 998D

I'm sure someone has gotten fake rosin/flux from china. I just wanted to know what the characteristics are like... is it so bad that it doesn't work, or is does it work but poorly?

[momaka]

Re: First QFN removal with budget solder Huakko station 998D

Nice work jondoe!

Don't be afraid to crank the heat up. Hot air doesn't work exactly like a soldering iron, so you need hotter temperatures and longer exposure.

If you have a small bottom heater, though, you can often make your work a lot easier. I typically use the gas burner on my stove set on low. It actually does a perfect job of even heating on the bottom where I want to work.

Just keep this in mind if you have to remove bigger stuff with hot air.

I'm sure someone has gotten fake rosin/flux from china. I just wanted to know what the characteristics are like... is it so bad that it doesn't work, or is does it work but poorly?

One word: Kingbo
Apparently it's a cheap Chinese paste flux that varies in quality depending on where you get it from. It's also not regular rosin, but RMA (Rosin Mildly Activated). I think most re-work fluxes are RMA anyways, though.

In any case, I've tried several different Kingbo fluxes, and even the worst ones are not that bad. They just smell worse and smoke more. But they work.

As for Amtech fakes - there's a lot more variation. Apparently I have a small leftover in a syringe (picked up from the trash of a repair shop back in 2012), and it's fake, but it's not that bad. However, I have seen first hand how bad some of the fake Amtech fluxes can be - they literally leave a burned crust all over the board that is impossible to clean. They also dry out and crust way before reaching proper reflow temperatures. But mine seems okay for the most part. I use it for regular iron soldering sometimes and have no problems with that.

[eccerr0r]

Re: First QFN removal with budget solder Huakko station 998D

Does Rosin Mildly Activated need a Return Material Authorization?

Interesting. I did get some cheap china crap and ...well... I think it's crap or at least it doesn't seem to work very well at all. It's orange colored, waxy soft at room temperature. It easily melts but does not appear to "work" at least compared to the solder wire core rosin like Kester 44, etc. It smells like rosin, and does not crust over when heated. It returns to a waxy state if it gets to cool back down before it all gets vaporized.

Again I don't know if I'm expecting too much or not. Even Kester 44 rosin, if it cools back down, it becomes brown and crusty, but will readily remelt and reactivate when reflowed.

[stj]

Re: First QFN removal with budget solder Huakko station 998D

there was a vid on utube - it may have been marcoreps, testing some "flux"
the conclusion was some of it could make a good soldermask!!!

[eccerr0r]

Re: First QFN removal with budget solder Huakko station 998D

Lol

[Th3_uN1Qu3]

Re: First QFN removal with budget solder Huakko station 998D

Interesting. I did get some cheap china crap and ...well... I think it's crap or at least it doesn't seem to work very well at all. It's orange colored, waxy soft at room temperature. It easily melts but does not appear to "work" at least compared to the solder wire core rosin like Kester 44, etc. It smells like rosin, and does not crust over when heated. It returns to a waxy state if it gets to cool back down before it all gets vaporized.

The orange stuff is garbage. Kingbo is alright, but the quality control leaves to be desired - you never know what's gonna be in your next can. It also makes a lot of smoke. But it's still 10x better than the orange stuff so if you're looking for cheap flux, Kingbo is the way to go.

For quality, another vote for Amtech NC559 here.

[momaka]

Re: First QFN removal with budget solder Huakko station 998D

there was a vid on utube - it may have been marcoreps, testing some "flux"
the conclusion was some of it could make a good soldermask!!!

Yes, I think I remember seeing a video like that before.

Also, regular liquid rosin flux not meant for rework or lead-free solder can also do the same - it hardens up and then makes it impossible to solder on top of it until you chip it away. I have some MG Chemicals regular rosin flux like that. It's wonderful for leaded and lead-free through hole soldering and smells nice too. But for BGA or SMD work - pretty bad!

Kingbo is alright, but the quality control leaves to be desired - you never know what's gonna be in your next can. It also makes a lot of smoke. But it's still 10x better than the orange stuff so if you're looking for cheap flux, Kingbo is the way to go.

Well, now that my jar of Kingbo is nearly 6 or so years old, it has changed its color from "pasty white" to "dark-piss" yellow over the years. And it smokes a ton more than before. But it still works, lol. I just don't use it for BGA work anymore because it fogs up the whole house (And I pretty much have stopped doing BGA work anymore).

[clearchris]

Re: First QFN removal with budget solder Huakko station 998D

I'm quite happy with my kingbo flux. Fluxes great, yeah, lots of fumes, don't breathe it. Clean-up requires brake cleaner, I haven't found anything else that will dissolve it. Mine has also turned dark, but I stick my iron in the paste all the time, it would look a lot nicer if I didn't do that.

[eccerr0r]

Re: First QFN removal with budget solder Huakko station 998D

Any ideas what the kingbo stuff is made of? Not rosin, at least it doesn't look it? That "100g" jar looks huge...wonder what's a reasonable amount at a good price/quantity ratio.

I need to get some better flux sometime. I got some acid flux which is no good for electronics, but I figure I have other stuff to solder and that's for that.

[momaka]

Re: First QFN removal with budget solder Huakko station 998D

I'm quite happy with my kingbo flux. Fluxes great, yeah, lots of fumes, don't breathe it. Clean-up requires brake cleaner, I haven't found anything else that will dissolve it.

I have no problems cleaning it up with IPA / rubbing alcohol.

I would NOT suggest using break cleaner at all. I don't remember what chemical most brake cleaners had, but it will dissolve aluminum and sometimes other metals too - definitely something you shouldn't use on a motherboard or anything with electronic contacts. Even Acetone can be damaging - but that's mostly for the plastics. I only use Acetone for the most stubborn cleanups I have to do. And even then, I always clean up any leftover residue with IPA.

Mine has also turned dark, but I stick my iron in the paste all the time, it would look a lot nicer if I didn't do that.

Yes, I think heat is the reason Kingbo flux turns yellow over time. A fellow technicial told me if you keep it in the fridge, it won't do that as quickly. But I am doubtful and I also can't be bothered to walk to the fridge every time I need flux, lol.

As for sticking your iron in the flux jar... doesn't that damage your tip's coating? If I use too much flux, I find my copper tips get eaten up fast and my steel-plated brass tips (mostly T12/T15) get gunked up and solder won't stick to them anymore. So I tend to use my flux sparingly and also NEVER apply it on any of the tips.

[clearchris]

Re: First QFN removal with budget solder Huakko station 998D

I have no problems cleaning it up with IPA / rubbing alcohol.

Yes, I think heat is the reason Kingbo flux turns yellow over time. A fellow technicial told me if you keep it in the fridge, it won't do that as quickly. But I am doubtful and I also can't be bothered to walk to the fridge every time I need flux, lol.

As for sticking your iron in the flux jar... doesn't that damage your tip's coating? If I use too much flux, I find my copper tips get eaten up fast and my steel-plated brass tips (mostly T12/T15) get gunked up and solder won't stick to them anymore. So I tend to use my flux sparingly and also NEVER apply it on any of the tips.

My kingbo flux laughs at 98% rubbing alcohol. Also tried everclear, no love. Haven't tried acetone because it does dissolve a lot of plastic.

I have a real Hakko chisel tip, and no problem dipping it in flux. I dip it into the flux, clean with brass scrub pad, and it comes out perfectly tinned. I did have some aftermarket tips, and they were terrible. Couldn't transmit heat at all. So I haven't a clue how they perform dipped in flux, etc.

I have been tempted to get a T15 setup, but my experience with non-hakko tips has kept me away.

[momaka]

Re: First QFN removal with budget solder Huakko station 998D

I have been tempted to get a T15 setup, but my experience with non-hakko tips has kept me away.

T12/T15 tips are awesome! Or any other tip with built-in heating element and sensor for that matter (only mentioning this because I don't know what JBC calls theirs).

If you are using Hakko 900M tips, you'll never go back to them after going with T12. Granted genuine Hakko 900M tips are probably fine. But the aftermarket ones are a total disaster, as you noted. I have an iron/station with those, and I use it mostly for engraving wood and melting plastic - that's about all it's good for. Soldering? -HA! I can maybe solder two 22 AWG wires together if I crank the heat up to 400C, lol.