Steve,

If I encounter a syringe with a few random, large, air bubbles I will tamp it on the work surface with the syringe tip "UP" and tip cap "OFF".  I will then slowly push the piston and extrude some of the material and air out the tip.

This works for large[r] bubbles, but would be hopeless in your situation.  Retire that lot back to the vendor immediately!  If there is this much air along the inside of the syringe, just imagine the corresponding air within the bulk of the syringe.  The piston of the syringe is pushing on a sponge.  Dispense control will be difficult.

If like adhesives, will typically fill by pressurized transfer from a larger vessel through the tip of the finished-good syringe.  

I would not centrifuge solder paste ... too much density differential between constituents.  Even centrifuging of conductive & non-conductive adhesives can lead to problems if one gets carried away.

Bet your operators were about ready to throw the syringes at you!  Dispense needles still on??

Steve C

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Wednesday, February 22, 2012 7:52 PM
To: [log in to unmask]
Subject: [TN] Air Bubbles in Syringes of Solder Paste...

Hi All,

I have a question about syringes of dispensable solder paste. We purchase 10cc syringes of Type-4 dispensable solder paste for work that we do. It’s used much of the time to dispense paste for the stacked capacitors that we do, much of the time it’s for 0402 caps, so the dispensing has to be very precise.




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