Soldering paste....which one?

[boylesg]

I have never attempted surface mount soldering with solder paste so I need some guidance here.

I get the impression that they can have differing melting points.

Differ by a significant amount for different applications or it doesn't matter that much?

And what about the flux carrier? Is it better in some solder pastes than in others?

We will be soldering WS2812Ds and we will have a ***** at soldering some surface mount bypass caps.

 

[KlausST]

Hi,

for testing purpose you may use a leaded one. With a melting temperature of about 180°C.
It´s easy to use and gives good results.
I recommend a standard one which contains no_clean_flux.

Klaus

 

[boylesg]

Well I am totally confused!

What is the difference between all of these solder paste products?

https://www.banggood.com/search/solder-paste.html

 

[schmitt trigger]

I cannot over-emphasize how important is to have a correct reflow solder profile for SMT work.

How have you set up your reflow oven?

EDIT;
For fine pitch and BGA work, you require solder paste that flows easily thru the solder stencil.
This is accomplished many ways, which include smaller solder sphere size and the use of surfactants.

What size components are you planning to solder?

 

[boylesg]

I cannot over-emphasize how important is to have a correct reflow solder profile for SMT work.

How have you set up your reflow oven?

EDIT;
For fine pitch and BGA work, you require solder paste that flows easily thru the solder stencil.
This is accomplished many ways, which include smaller solder sphere size and the use of surfactants.

What size components are you planning to solder?

We were going to trial it with a small USB soldering iron.
Just a few WS2812s and a SMD bypass caps.
No good?

Were are not going to be attempting anythng like this:

For fine pitch and BGA work

 

[KlausST]

Hi,

you could do with a kitchen oven.
Two aluminum plates (1cm or thicker)
one thermometer for each plate
one for preheat
the other for soldering

****
Different types.
It depends on many things.
Use a higher melting temperature if your PCBs are for high ambient temperature.

Use two different metling temperature solder paste for two sided assemebled PCBs.
First assemble and solder one side with high temperature solder paste.
Then assemble the other side with low temperature solder paste. Choose a soldering temperature that the second one melts but not the first one.

Klaus

 

[boylesg]

Where dealing with single sided soldering here and what is probably more important is a paste that is quite sticky so that the components are less likely to slide around easily when we apply the soldering iron.

Are there any such solder pastes on the banggood site that you would recommend? Or ebay?

One of those temperature controlled hot plate things they use in chemistry labs would probably work OK for single sided stuff....and would be more portable.

- - - Updated - - -

For $30 to $40 au these hot plates should work perfectly fine for lower melting point pastes.....just a matter up upping the power until a test dob of solder paste melts.

https://www.ebay.com.au/itm/Portable-Single-Electric-Hot-Plate-Cooker-Hotplate-Cooktop-Stove-Caravan-AU-Plug/192288314763?epid=2205618030&hash=item2cc546d58b:g:LFwAAOSwridaFQ~I

For our purposes it seems to me that this one from banggood is the most appropriate: https://www.banggood.com/10g-Weak-A....html?rmmds=search&stayold=1&cur_warehouse=CN

Method of use :
1. Using the end of a match or toothpick, apply a little soldering paste to the leads that will be soldered.
2. Place the soldering iron tip over the leads. Contact the solder against these leads. Heat the solder till it flows freely, then quickly move the soldering iron and solder away.

Are there any reasons that you experts can think of why we shouldn't use this solder paste give we are soldering single WS2812s?

 

[c_mitra]

Important to remember that some soldering paste contains solder and flux while many soldering paste is ONLY flux and NO solder. You need to use one that has both flux and SOLDER (dark gray color).