Glass Frit Bonding

Anas Al-Azawi

05.03.2013

Principle of glass frit bonding

Using glass glass as a special intermediate layer

Advantages: Hermetic sealing, metallic lead - throughs,narrow bonding frames, and high bonding yield

Glass Frit Materials

Low melting point glass which allow reflow in the temperature range 400C- 450C

Main components of Ferro FX -11-036 glass frit paste

RoHS directive constrict the use of lead additves

Screen Printing

Bond frames are structured in silicon and printed with glas frit paste

Structurd film supported by the mesh

Thermal Conditioning

Organics from the binder and te solvents would cause large bubbles in the glass at the process temperature at which the glass compound melt and wet he surface

Three step thermal preprocess to burn out the primer and to transform the paste into real pre melted glass is essential for higj quality bond

Thermal Conditioning 1) Directly after printing, the glass paste has to be dried and stabillized at 120C. Solvents disappear and the binder is internally crosslinked and stabillized2) Binder is burned out at 360C. Glass is not melted but viscosity is reduced. Complete burn out takes 10 min.3) The glass particles are completely melt and fuse into glass at 450C. Filler particles are enclosed in the glass but not fused into it.

Wafer Bond Process

The bonding process, which is,from the physics, driven by temperature, has to be supported by mechanical pressureon the wafers, in order to compensate for wafer bow influences and screenprinting inhomogeneities

Wafer Bond Process