dear sir, please giving the answer .
In the new metalliser I’m listen there is moving source of evaporation for drum distance we can change according to the product specification . is this system is successful or not?
please reply or thanks in advance.
Answer
In general the source to substrate distance is set at a distance to optimise the collection efficiency of the evaporant onto the drum at the deposition pressure. Some machines do allow you to alter the source height. If you move the source closer to the deposition drum the evaporant will deposit onto a shorter distance and so the heat load will be higher. Also as the boat separation is the same the thickness variation is likely to be larger than at the set source to substrate distance. If you move the source further away the evaporant will deposit over a larger area and so the evaporation shields will need to be repositioned. It is likely that the yield may fall as the collection efficiency may fall. The heat load will be reduced as the depositing material is spread over a larger area as well as possibly a slightly lower flux. If the source to substrate distance is altered then any uniformity shields will need to be changed to compensate. Unless you have a very specific reason for altering the source to substrate distance it always appears, to me, like a lot of work for little advantage. I hope this answers your question.
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