Ceramic Preparation

Tech-Ceram multilayer packages are produced utilizing a co-fire process. Ceramic powders are prepared via a milling process of precise amounts of raw materials into a homogeneous mix or slurry. The slurry is comprised of ceramic powders of controlled particle sizes with added amounts of organic binder materials and solvents. The slurry is transferred on to a Mylar carrier and then passed under a tightly controlled blade to produce a uniform thickness of ceramic “green tape”. After drying the tape is cut into rolls or sheets for additional processing.

Metal Deposition

Packages requiring via holes, edge castellations and cavities are punched out in the green state via special tooling and automated punching equipment. Via holes are filled with a refractory metal (Tungsten) paste to become vertical electrical interconnections between the layers. Precision screen printing is used to create conductive circuit patterns onto the ceramic “green tape” in a Clean Room environment using refactory metal pastes.

The ceramic tape layers are then stacked and laminated together using various techniques. Additional scoring may be done to facilitate snapping of individual parts from the array after post-fire, or individual packages may be punched out of the array prior to firing.

High Temperature Firing

The “green tape” ceramic with refactory metal deposition is co-fired at temperatures up to 1600 degrees C in a tightly a controlled atmosphere. The firing process will cause the ceramics to shrink approximately 18% in the X, Y and Z dimensions.

Post-Fire Brazing/Plating Processing

Ceramic packages requiring metal components to be attached such as leads, seal rings and heat sinks are plated with Nickel so that all exposed metal surfaces are covered to allow brazing and solderability. Metal components are attached by brazing with silver or a silver-copper eutectic alloy to form a hermetic joint.

Final package plating will be electrolytic gold. Electrolytic plating requires that all exposed circuits be temporarily electrically connected through a lead frame, internal tie bar or some combination of the two.