Solder pastes - Which to buy for first time smd soldering? - Page 1
Forum section: electronics / beginners

author: Gpanos
author_rank: Newbie
timestamp: July 08, 2013, 11:34:53 am
content: Hi all,[Forgive me for any mistakes, but this is my first post in this forum!]I am very new to smd soldering with solder paste and hot air stations. I want to start making some prototype smd/smt boards with several fine-pitched componentsthat, from what I have read, require reflow soldering (especially those QFN packages). I will not use any BGA ones.So, I have been searching on ebay and digikey for the various components and tools that I'll need, yet I have know idea which of all those solder pastes to select.I have found some cheap Chinese ones on ebay for 4$ the 50g (or 35g as it turns out to be), and also some more expensive ones on digikey.I am skeptical on whether the cheap ones will do the job or I am better off buying the more expensive one.Has anyone use those before ? Are they recommend ? Any alternatives/recommendations ?(I am probably going to use the ATTEN AT-858D+ that Dave has reviewed in one of his videos and seems like a good choice)Thanks in advance !

author: Krzysztof Szymiczek
author_rank: Newbie
timestamp: July 08, 2013, 11:55:52 am
content: Hi,At the begining - welcome to forum.As you are a beginner, and you own some basic hot-air station, you'll probably not want to spend more for the paste as for your station.Stick to one brand at the begin, I'm using some Polish brand AG PASTY, ex. ESN62PB36AG/8 which is not lead-free.Thus it will be probably hard to obtain abroad of Poland - choose something popular like AMTECH.I used to use AMTECH 223-ASM which is also not lead-free. Be aware that you'll probaby use to much of the paste at the beginning, so really don't go for the expensive ones...

author: Psi
author_rank: Super Contributor
timestamp: July 08, 2013, 12:17:27 pm
content: Remember to keep your solder paste in the fridge.Don't buy it if the shop is just storing it on a shelf.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: July 08, 2013, 12:25:39 pm
content: Anything with lead in will probably be fine. Some silver is also good.

author: ddavidebor
author_rank: Super Contributor
timestamp: July 08, 2013, 02:04:29 pm
content: Quote from: Gpanos on July 08, 2013, 11:34:53 amBuy a crap hot air station (i suggest the one with the pump inside the case, not the fan in the "pen"... Is more handy)And a hight quality professional solder paste, of some big brand name.For flux, stay with big brand too. Just search on their catalog for the one right for you.

author: woodchips
author_rank: Frequent Contributor
timestamp: July 08, 2013, 06:17:19 pm
content: Looks easy, but it isn't. Don't even think of using non-tin/lead solder, the tin only stuff is useless, with or without silver in it. You will find that a tiny syringe of paste will solder hundreds of components, you will throw away far more than you ever use. In the end I bought a hot plate rather than the hot air gun, temperature is more controllable which is important because over 232C there starts to form an intermetallic layer in the solder joint. There can also be soldered joints inside the component as well. See Smith, Optimising Quality in Electronics Assembly.In fact I would suggest you spend a few hours trying to unsolder surface mount devices from scrap boards first, gives some idea of just how much heat is needed, and therefore how big hot air gun, and therefore the temperature being wound up to 450C just to get some action.

author: trophosphere
author_rank: Frequent Contributor
timestamp: July 08, 2013, 06:42:56 pm
content: I haven't used any of the cheap Chinese ones before so can't help you there. However, I have been usingthisone and have gotten pretty good results even about a year and a half out from date of purchase.

author: Gpanos
author_rank: Newbie
timestamp: July 09, 2013, 12:32:14 pm
content: Thank you all for your replies !!I think I'll just buy some cheap leaded solder in the begging for practice (soldering & desoldering old pcbs) and then I'll try the more expensive ones.Quote from: ddavidebor on July 08, 2013, 02:04:29 pmAs for the hot air station, I want an inexpensive one and the best I could find was the Atten 858D. I hope the fan in the pen won't turn out to be a major issue (for start).Quote from: Psi on July 08, 2013, 12:17:27 pmThanks for the tip !!

author: 8086
author_rank: Super Contributor
timestamp: July 09, 2013, 12:49:23 pm
content: Quote from: Gpanos on July 08, 2013, 11:34:53 amI'm guessing you're talking about this kindhttps://www.eevblog.com/forum/reviews/some-solder-paste-to-avoid/While it may not be the weight you expect, it does work pretty well. I've used it for a few boards and had no problems. For a first try or a few boards it's probably your best option.

author: ddavidebor
author_rank: Super Contributor
timestamp: July 09, 2013, 12:51:50 pm
content: Quote from: Gpanos on July 09, 2013, 12:32:14 pmNo it's fine with the fan too, just a bit less handy.No problem at all for occasional use.

author: Corporate666
author_rank: Unknown
timestamp: July 09, 2013, 11:44:06 pm
content: I've used tons of different types.Stay away from lead free, unless you really need it. Total pain in the ass to use.Personally I highly recommend Kester R276. You can get it in small tubes for Stanley Supply/Contact East for $14 per tube. It will last longer and be more forgiving than anything else I've tried.The Chinese stuff, I have had mixed results. Solder paste is just the alloyed balls + the paste/carrier fluid. The Chinese stuff I've had some be pretty decent (not as good as R276 but not bad), and some that was total shite. Meaning - even when new, it flowed badly, and it lasted a week or two. The Kester stuff, I've opened a tube and still been using it 9 months later.If you are not specifically trying to save a buck or two (which you shouldn't be for a hobbyist), just save yourself a lot of hassle and get a tube of R276 from Contact East. Once you know more about how much you will use and if you need special features (no clean, water soluble, etc), then you can experiment.

author: Selectech
author_rank: Regular Contributor
timestamp: July 10, 2013, 12:08:04 am
content: I would recommend R276 as well. I use it with a shot dispenser { ebay special } and in a CNC dispensing system I made for myself.Easy to use, good solder joints.I've tried a few others, but this works best for me.

author: Corporate666
author_rank: Unknown
timestamp: July 10, 2013, 12:11:15 am
content: Quote from: Selectech on July 10, 2013, 12:08:04 amWell now that sounds interesting. Can you show us or tell us about this CNC dispensing system?I am very interested in such a thing. We have a lot of boards that aren't high volume and worth screens for and doing in volume, but are a PITA to do with a manual/pneumatic shot dispenser.

author: nukie
author_rank: Frequent Contributor
timestamp: July 10, 2013, 10:34:50 am
content: Since this is your first time, the consistency of the paste you buy should be creamy honey like. If it cakes or look dry you should return it.