SMT printing has focused on the use of stainless steel and stainless steel derivative materials for stencil materials. The reasons for this choice are based on performance and cost. The 300 series of stainless steel was once the most common. There are a variety of different 300 series types as well as other alloys which are now the most commonly used materials. These materials have tended to give better release and cut and aperture wall qualities. Some of these new materials are better-suited for the laser machining process.
The one chosen by BEST as its standard material for SMT stencils is a high nickel content stainless derivative known as PHD. PHD material is a higher end material that provides several benefits to the SMT manufacturing process. This material has a smaller grain which results in better release properties as the aperture walls are smoother. This surface presents fewer places that the paste will remain “stuck” once the paste is released. This property results in better print quality for SMT printing operation.
Small Grain Structure Means Better Paste Release
The flatness of the PHD material and its heat withstand properties are better than standard grade 300 series stainless steel stencils. During laser machining the localized heating of th3e laser beam can bend and buckle the metal thereby not giving you a perfectly flat surface. A flatter stencil insures that co planarity between stencil and board is assured. Solder paste does not get smeared underneath the stencil BEST SMT stencils deliver these superior heat withstand properties meaning that the surface stays flat even after laser machining or printing.
Superior Side Walls Gives Better Paste Releae
Try one of the BEST stainless steel stencils and see for yourself.