What size dispensing tip for 0402 SMD?

[peps1]

Hey guys, 

I'm new to SMD but have some Arduino Mini Pro boards coming with a couple of 0402 package components that need to be soldered (got very frightened when those components came today and I saw just how small they are!!!)

I was just wondering what gauge dispensing tips I should order to give me a fighting chance!

(any other tips on dealing with such tiny packages would be very welcome too)

[Corporate666]

We use 15 gauge (luer lock) nozzles for all dispensing - they are predictable.  Much smaller and you need a ton of pressure to get any flow.

We control the dot size with air pressure and dispense time. 

I'm guessing you are using a pneumatic dispenser since you're asking about this? I'd start around 50psi.. the lower the pressure, the more leeway you have in dispense time.

[peps1]

I'm guessing you are using a pneumatic dispenser since you're asking about this?

Nope, just using a normal syringe....but, the one I got didn't come with any form of tip or nozzle, just a rubber stopper. 

[mazurov]

You don't need paste - just tin the pads making sure not to pour too much, apply small amount of liquid flux to the tinned surface and hot air. If you still want to use paste, thin it with IPA to almost liquid state and apply with a toothpick. You can also apply paste to the part itself.

For 0402 I wouldn't even bother with reflow, it's big enough to be soldered with an iron. Tin one pad, solder one side by melting the tin on the pad and placing the part. Remove iron, turn the board around and solder other side. Liquid flux is your friend.

[peps1]

Thanks for the tips.

Unfortunately I have a tremor in my right hand that may make hand soldering such small packages hard.....hence why I quite liked the idea of SMD, as the parts tend to get dragged into place with the reflow if a bit wonky.

[metalphreak]

You are really limited to what size will actually allow solder paste through especially when doing it by hand. Compressed air makes things easier but there is still a limit to how small you can go. I find that the paste tends to stick to the nozzle rather than the pads sometimes as well.

You'll need larger tips doing it by hand than with a dispenser. Trying to push the plunger with enough force AND keep a steady hand is impossible. Also, you'll find that paste will keep squeezing out even after you stop pressing the plunger. Going with the toothpick idea might not be such a bad thing?