Electroformed stencils provide excellent performance for SMT boards that require printing of fine pitch components, BGAs, Ultra fine pitch QFPs, QFNs, and 0201 components. Electroforming is also a proven process technology for component applications requiring wafer bumping. As more soldering processes move to lead-free manufacturing electroformed stencils with its excellent paste release characteristics are well suited for lead free paste formulations.
Stencils are formed by a process of attaching nickel atoms to a conductive mandrel surface. The mandrel surface then has the negative photoresist image of the stencil aperture patterns applied. The photoresist coating is polymerized by light exposure through a photo mask of the broad pattern. While developing, a negative image is created on the mandrel surface. This causes only the aperture locations to be covered by the photoresist. The nickel atoms are then attached to the remaining areas of the mandrel surface. When the correct foil thickness has been achieved, the photoresist is cleared and the mandrel is removed from the foil. Electroformed stencils are available on mesh mounted standard frame or foil.
AGIs Electroformed Stainless Steel Stencils are manufactured from, 302/304 Stress Relief Annealed (SRA) Stainless Steel, Fine Grain, <25 microns, Full Hardened, Certified Material. SRA materials reduce internal stresses introduced by prior manufacturing processes. Stress relief annealing is performed at temperatures below the phase transformation temperature and is not designed to produce significant changes in microstructure or mechanical properties. SRA SS material is ideally suited for stencil fabricators, chemical etching, and laser cutting applications.
Lower cost alternative to Invar and other controlled expansion alloys
Prevents cracking and distortion from heat
Increases resistance to brittle fracture
Minimizes stress corrosion cracking in service environments
Features and Benefits
Available thickness 1 mil to 12 mil in .01 mil increments
Aperture capability: from 1 mil
Component pitch 4 mil onwards
Available foils: VAHT, Mid-seal, Low-seal, VectorGuard
Smooth trapezoidal sidewalls for maximum paste release
High seal capability for 1:1 aperture to pad for lead-free processes
Improved paste release performance, excellent for lead-free formulations
Stencils are formed by a process of attaching nickel atoms to a conductive mandrel surface. The mandrel surface then has the negative photoresist image of the stencil aperture patterns applied. The photoresist coating is polymerized by light exposure through a photo mask of the broad pattern. While developing, a negative image is created on the mandrel surface. This causes only the aperture locations to be covered by the photoresist. The nickel atoms are then attached to the remaining areas of the mandrel surface. When the correct foil thickness has been achieved, the photoresist is cleared and the mandrel is removed from the foil. Electroformed stencils are available on mesh mounted standard frame or foil.
Stencil Data Sheet.pdf
AGI Stencil Order Form (right click to download form)
