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Paste Solder
- Thread starter SamR
- Start date
How steady are your hands? I don't like Solder Paste for DIY SMD soldering. I hand solder everything with a fine tip iron and a hot air gun, using magnification if needed.
https://forum.allaboutcircuits.com/...-pcb-what-is-the-best-way.182299/post-1672597
Funny you should mention that, which is why I'm asking. I can't hand solder size 6 or smaller due to what they call essential tremor (old age). What works best for me is paste flux the board and wiggle the component around until it's in the perfect spot. Then bake it. So, I got a nice but cheap soldering plate but it was way too large a space for the small boards I was making. Then I got a deal on a very small one. But I presoldered the attachment points on the board for the components. Which makes a very lumpy board to balance the components on. So... Which leaded paste are you using and I would prefer leaded.
This is one of those occasions I would actually recommend lead-free solder for safety reasons. We all know that lead is toxic, but that in the form of reel solder it is reasonably inert. However, the easiest route to ingestion is finely divided particles which is exactly what solder paste is. As it contains all the flux, and the right flux, that it needs to work, tin-lead doesn't have so much of an advantage in ease of use.
I use the tin-silver-copper alloy from Solder King https://solderking.com/solder-pastes/ I'll tell you the exact one when I'm at work, and keep it in the fridge, otherwise, it sets by itself if you don't use it.
I have used it on a hotplate (less successful) and with a hot air gun and in a modified table-top oven. If using the oven, the rate of temperature rise that it naturally achieves is about right, but it does like to remain a while at the preheat temperature before the final melt.
With hot air, I have soldered complete boards using a paint-stripper. Check the temperature before you start and don't use the maximum air flow (otherwise small things blow away). Put the board on something thermally conductive (I used an upside down baking tray) as that preheats other areas of the board as you go. Avoid formica benchtops - that stuff really stinks if you singe it!
I use the tin-silver-copper alloy from Solder King https://solderking.com/solder-pastes/ I'll tell you the exact one when I'm at work, and keep it in the fridge, otherwise, it sets by itself if you don't use it.
I have used it on a hotplate (less successful) and with a hot air gun and in a modified table-top oven. If using the oven, the rate of temperature rise that it naturally achieves is about right, but it does like to remain a while at the preheat temperature before the final melt.
With hot air, I have soldered complete boards using a paint-stripper. Check the temperature before you start and don't use the maximum air flow (otherwise small things blow away). Put the board on something thermally conductive (I used an upside down baking tray) as that preheats other areas of the board as you go. Avoid formica benchtops - that stuff really stinks if you singe it!
I have a hot air gun so I know about blown away parts. I've seen articles on ovens and using 3 stages, preheat, heat, and hold but never looked into buying one although I heard of folks using toaster ovens. I keep a silicone rubber mat on top of my plastic laminate benchtop along with a cutting mat that can be replaced. So far, no burns. Aha, the no-lead solder requires lower temps! I assumed it would be higher temp... Also, just how hard is it to apply without a stencil? Can it just be smeared on without a stencil?
Stencils are good, and fairly cheap from the usual pcb suppliers we all use. Without a stencil, you use the syringe and it’s like icing a tiny cake, one blob on each pad, and after you have done a few, you will have the strongest thumbs in the world. (Winding toroids with 2mm wire is good thumb exercise as well)
Smearing a load of it in the right general direction works, as it gathers itself together by surface tension and heads for the pads, but it is rather too easy to get too much of it or too little. Too little is the greater problem: too much is easy to see and the surplus can be removed with a desoldering pump. Too little and you can get resistors that are only soldered at one end, but look as though they are attached, only to lose contact at a later date due to flexing and thermal cycling.
Smearing a load of it in the right general direction works, as it gathers itself together by surface tension and heads for the pads, but it is rather too easy to get too much of it or too little. Too little is the greater problem: too much is easy to see and the surplus can be removed with a desoldering pump. Too little and you can get resistors that are only soldered at one end, but look as though they are attached, only to lose contact at a later date due to flexing and thermal cycling.
