Solder for SMD. - Page 1
Forum section: electronics / beginners

author: rounsmith
author_rank: Contributor
timestamp: February 18, 2012, 08:26:34 am
content: Hello eevblog community !I am Chris , a guy that his hobby is building electronics circuits(i am graduating as an Computer Engineer).I just start setting up my lab lately , and i am ordering things around so i can complete my lab(and maybe post some pictures here when it is done). I will be propably be doing a lot of projects around ?C so yeahAnyhow ! Enough with the talking , lets get into business. So here is my question !I want to buy locally some good solder (outside from greece is really hard to find that diameter i am seeking for , like 0.8mm or less, and i am not trusting those pesky chinese sellers on ebay). So yeah...Ishttp://www.acdcshop.gr/soldercynelalloylc60025kg-p-6098.htmla good leaded solder?it's 0.25mm , doesn't say in description and has 5 cores of flux ( I will be avoiding using lead-free since from what i saw from Dave's videos it's kinda not recommended even if it's enviromental friendly).

author: IanB
author_rank: Super Contributor
timestamp: February 18, 2012, 09:13:00 am
content: Yes, that solder looks fine. You might want to get some solder of different thicknesses for different kinds of job. For example the thicker wire like 0.8 mm will be good for bigger joints like wiring or solder lugs.

author: rounsmith
author_rank: Contributor
timestamp: February 18, 2012, 01:00:26 pm
content: Oki thank you very much for the replies ! then it is one spool of 0.25mm and one 0.8mm

author: Randall W. Lott
author_rank: Regular Contributor
timestamp: February 28, 2012, 01:48:04 am
content: I have a $20 toaster oven that has a controllable temperature and I use it to solder all of my SMD parts.I read all of my components' datasheets and look for the most sensitive component.Solder paste is applied. I use a kind that does not need to be refrigerated.The components are placed with tweezers.I place a thermocouple on the most sensitive component so I can monitor it.Ding! Dinner is ready!Solder joints are inspected and touched up based on their adequacy.Through-hole components are placed and soldered.I recommend this process as it saves time and it's been quite reliable for me. It's extremely important to monitor the temperature as the dial on the oven doesn't correlate to the exact temperature. The actual temperature was 20ohigher than its claimed value! Good luck on your SMD soldering.

author: rounsmith
author_rank: Contributor
timestamp: February 29, 2012, 12:14:03 pm
content: Thank you very much for your answer , might try it

author: sacherjj
author_rank: Frequent Contributor
timestamp: February 29, 2012, 02:25:18 pm
content: The easiest way I've found to solder SMD is to pick up a hot air iron. (Useful for so many things.) And then get some solder paste. Dab of paste on each pad. Drop a component with tweezers. Hit with the hot air and watch it flow into place. Run a thin line along ic pin pads, heat and watch the solder ball up and fall off the solder mask. The biggest problem is using too much paste.

author: T4P
author_rank: Super Contributor
timestamp: February 29, 2012, 06:26:54 pm
content: Quote from: sacherjj on February 29, 2012, 02:25:18 pmYep , you can never have not enough paste .Maybe using those medicinal syringes would do it's job

author: olsenn
author_rank: Frequent Contributor
timestamp: February 29, 2012, 06:53:38 pm
content: For SMD's, I've always just completely coated the pins with solder and soaked up the excess with a fine solder wick. It works well, it's easy, and it's cheap

author: sacherjj
author_rank: Frequent Contributor
timestamp: February 29, 2012, 07:13:40 pm
content: Quote from: Dave.S on February 29, 2012, 06:26:54 pmWell you can, but it seems to be harder. At least in my experience. Components really require a tiny amount. Looking at the thickness of a typical solder paste template, it doesn't put much on each pad.The problem is that the medical syringe is trying to push a high viscosity liquid through a thin syringe. Control is poor while pushing hard and I typically get too much.

author: T4P
author_rank: Super Contributor
timestamp: February 29, 2012, 07:30:28 pm
content: Quote from: sacherjj on February 29, 2012, 07:13:40 pmI usually just put more flux in it .

author: markus_b
author_rank: Regular Contributor
timestamp: February 29, 2012, 07:52:36 pm
content: Quote from: Randall W. Lott on February 28, 2012, 01:48:04 amDo you have a reference for this solder paste ?The need to refrigerate (and the limited time you could keep it) have driven me away from solder paste for now.

author: sacherjj
author_rank: Frequent Contributor
timestamp: February 29, 2012, 08:18:49 pm
content: Quote from: markus_b on February 29, 2012, 07:52:36 pmSeconded. I think that is part of my viscosity problem is that I pull it out of the fridge 15 minutes before I need to solder.

author: nanofrog
author_rank: Super Contributor
timestamp: March 01, 2012, 12:49:02 am
content: Might be AIM solder paste (http://www.aimsolder.com/), which has a 6 month shelf-life non-refridgerated (@ 22C/72F), or 1 year if it is stored in the fridge (@ 4C/40F).

author: markus_b
author_rank: Regular Contributor
timestamp: March 01, 2012, 06:36:53 pm
content: Quote from: nanofrog on March 01, 2012, 12:49:02 amThat is exactly my problem with solder paste: I'll probably use it once a year. That means I'll have to plan ahead and buy fresh ration every time I use some. I'm looking for something with a shelf life of 10 years, without refrigeration !

author: nanofrog
author_rank: Super Contributor
timestamp: March 02, 2012, 12:24:40 am
content: Quote from: markus_b on March 01, 2012, 06:36:53 pmSame here.So I'll stick with drag soldering. At least I can add more flux with old solder instead of tossing it.

author: robrenz
author_rank: Super Contributor
timestamp: March 02, 2012, 02:01:08 am
content: Quote from: Dave.S on February 29, 2012, 07:30:28 pmI have found that adding Isopropyl alcohol works great. The don't think the flux itself goes anywhere, I think the solvent in the flux slowly evaporates through the syringe wall. I have had like new performance on old solder so stiff it would not dispense.

author: Randall W. Lott
author_rank: Regular Contributor
timestamp: March 02, 2012, 03:54:51 am
content: Quote from: markus_b on February 29, 2012, 07:52:36 pmSMD291AX. It lasts over a year and needs no refrigeration.I use a very small nail to place it on the pads after squirting a glob onto a piece of paper. The tip that comes with it doesn't provide enough precision for me. Applying too much is the biggest problem you can have. It works very well if you take the time to apply the correct amount. I suggest a grain of salt size for 0603 pads. You can always touch it up after.

author: robrenz
author_rank: Super Contributor
timestamp: March 02, 2012, 04:27:48 am
content: Quote from: Randall W. Lott on March 02, 2012, 03:54:51 am1 year is refrigerated 6 months @ room temphttp://www.chipquick.com/smd291ax.htm

author: electroguy
author_rank: Regular Contributor
timestamp: March 02, 2012, 04:41:32 am
content: Quote from: robrenz on March 02, 2012, 04:27:48 ami have used this on its own, and it is pretty good.However, it works much better together with the flux SMD291NL

author: T4P
author_rank: Super Contributor
timestamp: March 02, 2012, 12:08:42 pm
content: I buy some real and cheap solder paste from dealextreme (3$ for 50g , NO JOKE! )So if it expires it's not much of a loss anywayhttp://www.dealextreme.com/p/mechanics-soldering-paste-50g-7952When it hardens just mix some flux of your own ... RMA/Noclean anything .

author: metalphreak
author_rank: Frequent Contributor
timestamp: March 02, 2012, 01:11:05 pm
content: Quote from: robrenz on March 02, 2012, 02:01:08 amI've found adding isopropyl alcohol to usually be a bad idea, unless you let the alcohol fully evaporate from the paste before reflowing it. Otherwise, if your ramp up the heat quickly (ie short or no heat soaking phase) the paste tends to "pop" and "spit" blowing small components off the board (I assume this is the alcohol boiling off). Best thing I've found to use is the greasy/waxy paste type of soldering flux you can get off dealextreme in small tubs.Edit: this stuffhttp://www.dealextreme.com/p/high-intensity-soldering-paste-150g-7923

author: robrenz
author_rank: Super Contributor
timestamp: March 02, 2012, 02:42:03 pm
content: I havent used oven reflow, I am using a iron so I havent see that occur but good to know.

author: metalphreak
author_rank: Frequent Contributor
timestamp: March 02, 2012, 03:24:34 pm
content: It could just be that my paste was too far gone, and a lack of proper flux is what caused it. I had the same thing happen when hand soldering but to a much lesser extent. Desperate measures when its the last tub of paste left

author: T4P
author_rank: Super Contributor
timestamp: March 02, 2012, 03:33:58 pm
content: Quote from: metalphreak on March 02, 2012, 03:24:34 pmNot so desperate if you buy cheap pasteAnd yes , i don't know what alcohol i'm using ... But it doesn't spray everywhere .

author: Randall W. Lott
author_rank: Regular Contributor
timestamp: March 02, 2012, 04:32:50 pm
content: Quote from: robrenz on March 02, 2012, 04:27:48 amDigi-Key datasheet fail. There are corrupted characters in the PDF which most likely explain the recommended refrigeration. Thank you for mentioning this to me.

author: metalphreak
author_rank: Frequent Contributor
timestamp: March 02, 2012, 04:39:49 pm
content: Quote from: Dave.S on March 02, 2012, 03:33:58 pmHaha yeah I get the mechanics stuff from DX, but when the next batch is 2 to 8 weeks away in the HK post system...

author: T4P
author_rank: Super Contributor
timestamp: March 02, 2012, 04:49:55 pm
content: Quote from: metalphreak on March 02, 2012, 04:39:49 pmThen sit back and relax

author: nukie
author_rank: Frequent Contributor
timestamp: March 04, 2012, 12:09:32 am
content: plenty of suppliers who will ship you the same stuff at slightly higher price you don't have to go with DX all the time. Since its cheap why not order in advance? I find lonestar and mechanics brand works pretty well. They are water based flux.

author: nukie
author_rank: Frequent Contributor
timestamp: March 05, 2012, 11:39:04 pm
content: My suggestion is for people who don't want long lead times or MIA. I have been waiting for my DX thin hdmi cable for 3 months now. There are a lot of BGA work suppliers they charge slightly higher price for the reason being registered post. And by slightly higher prices I mean 1 or 2 more bucks. Shop around, DX is not the only place and not the most suitable place for PCB work supplier. Some of these specialist are based in HK and they have been around long before DX. I am not going to advertise for them you can search around using common keyword.

author: metalphreak
author_rank: Frequent Contributor
timestamp: March 06, 2012, 02:10:20 am
content: http://ultrakeet.com.au/index.php?id=1Haven't bought any from them yet, but it seems like very good value