Dear netters on the cheering section( special attn to Aussilek, who is a very sensitive person),
the clogging mystery is not ended yet, but the end is near: Camalot's own specialists are soon landing in our line. During waiting we tried the idea to make a mathematical model of the system: paste cartridge, inlet, auger, pumphouse, syringe and paste. The modeller has a lot of NASTRAN/ANSYS stuff as tools, which we thought would make the whole thing a one week job, but forget that! There are so many unknown material parameters and such complex a matrix, that it would take one year to gather all inputs before calculation could begin, said our physicist. He recommended a way to find solutions based upon good empirical tests instead.

We have found that the paste has from 0.1um  to 25um large flakes, and according to the theories, the flakes stop sliding over each other at approximately 2um. Much over 2um the flakes will instead starting agglomerations, therefore some say, that a modern silver epoxy for high speed, 150um dot precision dispensing, should have a distribution of something like 0.2um to 2um. The paste manufacturer may not be to excited to assist in finding the best solution, not if you calculate how much paste will be sold when the dots are in the size  of what the fly left on your plate.

I have made an investigation of the pump and the auger, and I found a lot of interesting things that will certainly help. I doubt that even Camalot themselves have done a SEM examination on inside of the pump, we have! Now I understand better, what it is like to be a silver paste in a pump.....
To be cont'd and finished very soon
CU
Ingemar Hernefjord
Ericsson Microwave Systems

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