Solder sucker to clear up SMD pads - Page 1
Forum section: electronics / general

author: bson
author_rank: Unknown
timestamp: November 18, 2017, 12:39:39 am
content: I'm looking for a recommendations for a self-contained sucker that can be used to remove solder bulges from SMD pads when replacing parts... Ideally it would have say a sharp hot point and just suck it up as it melts. Wick is a bit limited in how much it gets off, and it tends to be a wee bit awkward for 0.5/0.65 pin pitches, so I'm wondering if there's anything better out there... Maybe a plain old desoldering iron?

author: tautech
author_rank: Super Contributor
timestamp: November 18, 2017, 12:47:46 am
content: When working with SMD I like to use a Pb based solder, one, it lowers the melting point and therefore is easier on pads/tracks with a lesser risk of them lifting due to too long dwell times.Secondly, it's easier to suck Pb based solder to get the pads relatively clean with a plunger sucker.If you want to take this methodology to the extreme, then use a silver bearing solder to lower the solder melting point even further.

author: KL27x
author_rank: Super Contributor
timestamp: November 18, 2017, 04:32:05 am
content: Confused. Are you talking about sucking the solder up from unpopulated pads? Or for wicking out the solder from populated parts/pads?If empty pads, wick won't be beat by anything, IMO.If populated, wick won't be beat by anything, IMO. And IMO, you don't want to suck away that much of your joint. The filet is an important part of the structural integrity. If wick isn't good enough for this, it sounds like you're already past the point of reason.

author: progrock
author_rank: Contributor
timestamp: November 20, 2017, 07:26:46 pm
content: I didn't get it for SMD really... but bought a Hakko FR-300 recently... I love it, much better than I had expected. Seems a little pricey till you hold it in your hands (or compare it to those insanely expensive desoldering stations... then I suppose it;s not pricey at all). It definitely does a good job, and I almost don't want to admit this, but shortly after getting it, I left it on by accident for something like 5-6 hours on one of it's higher temp settings (luckily I did by the Hakko 633 stand to hold it, and had it in a relatively safe place). Anyway, there's practically no evidence of that happening, and definitely still works perfectly. BUT, while mostly my own fault, one reason this happened is that the "ON" LED is in the front, and when placed on a stand, it's not facing you, and very hard to notice. Still, not something that is too hard to keep track of normally.Again, didn't specifically get this for SMD (got it after dealing with a TON of solder on an ebike controller, when replacing some parts), but it could work. Though, my next soldering based purchase, specifically for SMD, will be a pair of tweezers (prob JBC micro tweezers... once I build this UniSolder 5.2)

author: bson
author_rank: Unknown
timestamp: November 25, 2017, 06:10:10 am
content: I meant for cleaning up pads after desoldering a chip, before pasting, placing and reflowing a replacement.

author: mrpackethead
author_rank: Super Contributor
timestamp: November 25, 2017, 06:17:02 am
content: Wick and flux is your go to for this job. If its not workign for, keep practicing.

author: nanofrog
author_rank: Super Contributor
timestamp: November 25, 2017, 08:08:16 am
content: Quote from: mrpackethead on November 25, 2017, 06:17:02 am+1Also, the best tip I've found for this is a hoof/bevel shape (works better than a chisel IME).

author: nctnico
author_rank: Super Contributor
timestamp: November 26, 2017, 05:43:15 pm
content: Quote from: bson on November 25, 2017, 06:10:10 amIf it is a regular chip with legs like SOIC, TQFP, QFN, etc I wouldn't bother with cleaning the pads. Way too much risk things go wrong and rubbing pads from the board. What I do is remove a chip with hot air, apply flux and then use hot air to solder (reflow) the replacement in place. Afterwards some pins may need extra solder but thats it.

author: kalel
author_rank: Frequent Contributor
timestamp: November 26, 2017, 08:00:17 pm
content: Quote from: nctnico on November 26, 2017, 05:43:15 pmI guess you also save on some solder paste that way? I've never worked with those packages, but that method seems easier.

author: nctnico
author_rank: Super Contributor
timestamp: November 26, 2017, 09:12:25 pm
content: Quote from: kalel on November 26, 2017, 08:00:17 pmI don't use solder paste at all. Never used it because I think it will be way too messy for me without a good system to apply it in even doses. Flux, solder, an iron with a big tip and hot air are all I need. For the real heavy duty jobs I throw in a hot plate but that is more for heat sensitive MOSFETs soldered onto a continuous copper area.

author: mrpackethead
author_rank: Super Contributor
timestamp: November 26, 2017, 09:14:27 pm
content: If you are replaceing by hand a component and resoldering it with an iron that you have removed, there are very very few cases where you should use solder paste. I can only think of one very odd ball job that it made sense for me.If you are going to hot air reflow it, then you might, if you have a way to get the paste on sensibly, but unless you do, you are just going to cause yourself a lot of extra work.

author: KL27x
author_rank: Super Contributor
timestamp: November 26, 2017, 09:34:10 pm
content: I'm with nctnico and mrpackethead, at least regarding no-lead parts. Pretty much clean and reflux the pads, and go over them with the iron to get an even bead of solid solder on the pads. Then pin the chip down while reflowing. For leaded parts, though, I tend to use an iron. Even here, I might just clean the pads as much as possible with a bevel tip, rather than wick, for DIL parts. QFP is probably the only IC where I would use wick to clean the old solder from the footprint. And there's nowhere I will personally use solder paste unless it's with a stencil.There are plenty of other reasons to use wick, though. You might accidentally get way too much solder on the center pad. (E.g. there's a solder spike/streak that you try to remove but you forgot to wipe the tip of your iron clean, first). Wicking this away can make the job easier.Also, for certain boards, such as homemade boards with no soldermask, it may be very helpful to wick the board off. Here, I agree with nanofrog. A stupid fat bevel tip is pretty hard to beat for heavy wicking jobs.But a good portion of the time I use wick, it's for little SMD connectors, where you can't easily reflow them without melting them. And no matter how you get them on, the over-tall pins/spring-contact-ends don't release their bridges to a soldering iron tip. These type of parts are practically the only reason I really need wick. Not that is it isn't helpful for lots of other things.While any brand of wick will work sufficiently with some flux added, I find there is a big difference between brands. A lot of people like chemwick, and I am also a believer. If you don't have to add flux, so much the better, methinks. I hear multlicore is also good, but chemwick is cheaper and better availability to me. The chemwick is also woven in a way you can cut it into a thinner strip, if you need to, and it doesn't fray or fall apart. There are least two different kinds of chemwick, though, IIRC. I don't know which one I have or what is the difference.

author: bson
author_rank: Unknown
timestamp: December 04, 2017, 04:50:53 am
content: Well, I can report a Hakko FR-300 works great with the stock nozzle. No need for flux, just tin the nozzle a little - it vacuums the pads super clean. Repaste, place, hot air and well, it can be repeated MANY times neatly and cleanly. It can also be used to remove excess HASL if it's uneven or heavy, so no need to pay for ENIG if you just have one or two parts that like to sit flat.

author: bson
author_rank: Unknown
timestamp: December 04, 2017, 04:53:14 am
content: Quote from: nctnico on November 26, 2017, 09:12:25 pmI use it for all SMD work.