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Pre-purchase considerations: SMD stencil specifications.
There are several important factors to consider before purchasing an SMD stencil.
- Stencil Thickness: Stencil thickness is a key factor in determining the amount of solder paste that will be applied to the board. Too much solder paste coverage will result in solder bridges, and too little paste will result in weak solder joints. Packing density also dictates a certain film thickness
- Size of openings: The stencil aperture size should be designed smaller than the PCB pad size to avoid problems such as bridging and solder balls. Otherwise, solder paste may stick to the walls of the opening when the stencil comes off. Therefore, to avoid such problems, the inner area of the aperture walls should be designed 2/3 smaller than the PCB pad area.
- Stencil material: The most commonly used material is stainless steel, but some PCB designs with fine pitch devices require the use of other materials such as FineGrain or nickel.
- Stencil Alignment: Proper SMD stencil alignment is critical to obtaining accurate solder paste printing. Alignment marks should be added to both the PCB and the stencil to achieve a perfect printing effect. These fixed points ensure correct alignment between SMD stencil and PCB.
Our experts will be happy to advise you on this!
