Solder paste reflow without stencil?

Thread Starter

Razor Concepts

Joined Oct 7, 2008
214
Is it feasible to do reflow with hand-applied solder paste instead of a stencil? I want to solder a adxl335 package accelerometer (no pins, just pads on bottom like QFN). It may not be ideal, but it would work good enough, right? Thanks.
 

SgtWookie

Joined Jul 17, 2007
22,230
Sure. Use a syringe with solder paste in it. You can order them online. I think they have a shelf life of about 6 months.
 

achilez

Joined Mar 23, 2010
6
I'm not sure a stencil has any inherent advantages over using a syringe/dispenser type except when the number of pads that need solder is large, and there is a need to get things done quickly.

I'm inclined to think that, for a small-pitched package like yours, a stencil might smear the paste, and that doing it manually would be more accurate (unless your hands are shaking from too much caffeine!).

BUT I don't have any evidence to back this up, so please, those of you with layout experience, correct me if this is wrong.
 

Tobias

Joined May 19, 2008
158
I have alot more luck with a syringe than the stencils. On a PCB board with around 20 components, a few of them small pitch, I could do the syringe faster and with better results. I had problems with the solder not sticking to some pads and smearing on others. I am sure with more practice it would have gotten better yet I really took to the syringe route quickly.

I keep my solder syringe in the freezer. Its atleast a year old and works great.
 
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