INVAR METAL INCREASES PASTE RELEASE ON LEAD FREE STENCILS

Due to the paste release characteristics and lower wetting forces of lead free alloys, manufacturers converting to lead free should evaluate the use of Invar metal for lead-free stencils.

The increased nickel content of Invar metal (compare 36% vs 6-8% on stainless steel) offers more lubrication (less friction), improving the paste release.

As a result of the higher nickel content, Invar offers the strength and durability of stainless steel, with lower thermal expansion to minimize dimensional changes. The fine grain structure also benefits the laser cutting process as it produces a cleaner and smoother cut under the laser head. 

It continues to be used successfully on fine pitch and BGA type configurations due to its paste release and transfer capabilities.

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