Matrix user forums

Hi
I experimented a bit with surface mount parts and I got to like it.
But with normal solder wire it is quite a Job to solder all the parts.
Now I am thinking of using soldering paste.
It seems solder paste is usually shipped with a cold pack.
Till it reaches me it will take about 3 week. About two weeks it will be exposed to temperatures of about 38° celsius.
What will the heat do to the solder paste? Will it become unusable or do I just have to mix it nicely?
What are your experiences?
To you keep it always in the fridge?

Best Regards:
Uli

Hi Uli
I keep mine in the fridge, even just getting it out the fridge to use after 1/2 hour or so it does get noticeably runnier im in the uk but where you are I don't know how the heat will affect it, have you any electronics repairers or manufacturers localish,if so try ringing them and asking how they handle paste, they may even be able to supply you some, you can get very fine solder wire online (try ali express or rapid online) which is good for smd parts I tend to add a bit of solder to each pad then add the component touch each end with your iron(you may need just a smidge of flux on the component, then keep the iron on the last side for just a second longer this should heat the solder at both ends and allow the component to centeralise on the pad, the best thing about paste is you can add a bit to each pad place each component then bake for a few minutes or even touch with a soldering iron

Regards
Dazz

Hi Dazz
Thanks for the info.
If it is just a issue of getting runny, and can be used again after being in a fridge then I could take the risk of ordering online.
But if it is an issue of the paste getting permanently changed then I would have to look into that.

Best Regards:
Uli

Hi Uli

Check out this video, might be helpful.

http://www.eevblog.com/2013/01/25/eevbl ... -tutorial/

Forgot to say always wear gloves when using paste it gets everywhere, there are some fairly cheap smd rework stations online, which combine an iron and a hotair blower, theres also lots of stuff on using tabletop ovens
Regards
Dazz

Hi
Thanks for all the replies.
Unfortunately I could not watch the video, my internet connection is too slow.
But I got some useful Information on the forum link.
Apparently it is a issue of the solder particles starting to separate and float on the top.
So I guess for me the best would be if I get some paste that is in a tin.
Best Regards:
Uli

Hi Uli,

This is quite a good guide on how to use a SMD oven and solder paste.

http://www.001tech.co.uk/index.php?p=proj&f=18&topic=60

The paste I buy does not come with a cool bag and I always generally just keep my paste at room temperature but the stuff I use has lead in it so it melts easier but not ideal for commercial applications. Longest I have had an open syringe is about 6 months.

http://uk.farnell.com/edsyn/cr44/solder ... /dp/876768

Hi I am just about to order some solder paste.
This will be my first time trying solder paste.
I can get a 35ml syringe, or a 250g Tin.
What can be kept longer a syringe or in a tin?
How much can I do with a 35ml syringe?

Just wonder if the solder tin will become unusable before I can ever finish it.

The other question is water soluble vs no clean what are your experiences?

Best Regards:
Uli

There are many types of solder pastes so it really depends upon whether or not it'll get damaged if exposed to higher temperatures. Mostly they work fine; in my lab they are not kept in any fridge or anything and they can be used for weeks. The lab is air conditioned when we are working but we leave them on the table after work without any worries. SMD soldering is easy if we're not talking about soldering DSPs or FPGAs or such. Also, the solder pastes are kept in tins here, I don't know about your working environment though.

turnkey pcb assembly

For future reference...

We use a variety of solder pastes at work, though all internal boards and prototypes are commonly soldered with leaded (i.e. NOT Lead-Free) paste.

For all prototyping applications I would strongly recommend avoiding lead-free paste, both for optimal reflow wetting and possible rework/modifications.


All the best,

Brendan