Novel dual layer electroformed stencils for high resolution LTCC circuit manufacture

This article reports the silver paste printing onto LTCC substrates at sub-100 μm linewidths using a microengineered electroformed dual layer stencil. It is demonstrated that such a stencil can serve as a screen replacement and print tracks of line widths down to 40 μms with a gap of 25 μm. Two commercially available Ag pastes designed for either screen printing tracks or stencil printing vias were analyzed to gain insight into what material properties are best suited for fine line printing using a dual layer stencil. It is shown that the same stencil and paste material can be used to fill in vias down to 200 μm diameter for ceramic green tapes of 50 μm thickness indicating that these line printing and via filling processes could be combined, allowing thereby increased throughput, resolution and registration benefit in LTCC manufacture.