01005 components and reflow profiles

I forgot to add that we are using a 3 mil stencil.
It seems like to me that may be there isn't enough flux left when we reach liquidous?? About half of the solder spheres do melt and wet on each pad, but the top half of each solder joint is just the solder spheres that will brush off easily.
I was thinking the next test board I run that I will keep the soak temperatures down and then hit it with the high reflow temps. I am concerned about tombstones then, among other issues that could arise.

Any suggestions would be appreciated.

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I haven't worked with anything as small as 01005s, but something you didn't mention is the %metal of your paste. I just switch from 90% to 89.5% (AIM NC257-2) and could tell the difference. Just an idea...

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you are seeing a typical issue that is caused when such small volumes of paste are printed....there are several reasons for it..the tiny amount of flux in the small deposit becomes exhausted much quicker then it does in a larger deposit ( the flux may bleed away from the powder when in the reflow oven). If you have no fluxing action left when the solder is above its melt temp then the solder spheres will not flow together.
The flux is the medium that transfers the reflow oven heat to the paste so if there is little flux and it is drying out fast then the solder powder doesn't get the heat transferred to it efficiently. Trying a paste with more flux may help reflow but will give issues with printing.
Ask your paste supplier for a paste with a thermally stable flux that is proven to reflow ultra small deposits.

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