For what it is worth, we are purchasing a dispensing system including a Robotic Arm, Positive Displacement Valve (as opposed to volumetric displacement) and Controller. We have purchased this unit for doing lead free 20 mil dots at 30 mil pitch in small batches, to supplement the rework tools that are available to the operators.
20 mil dot size seems to be the limit in dispensing. The other consideration is the resolution and repeatability of the Robot itself. +/-.02mm is going to work for us. +/-.01mm is available but of course is far more costly.
I&J Fisnar http://www.ijfisnar.com has a nice video trial process for showing what their systems can do, this in lieu of having a salesman do a demo in house. We provided the paste samples and examples of the PCB we are working on, they provide the video as "proof of process", and do not ship without your approval of the video. Was very helpful for us. Best of luck to you.
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