C-MAC developed different solutions to assure highest quality in hermetic solutions for it’s customers. A combination of ceramic substrate with a hermetic sealed solution to protect the circuit from its aggressive environment is a popular choice.

As ceramic is air and liquid tight, the substrate can be part of the enclosure; in that case a cap is soldered under specific conditions on the unit with an air & liquid tight solderjoint. This provides an economical and reliable solution. By doing this in a vacuum reflow oven, we can also assure an inert gas under the encloser which will avoid humidity and thus corrosion over time. In other applications, the circuit is glued or soldered in a housing which is closed hermetically with laser in a glove box after vacuum bake out. Inside the glove box, a mixture of noble gasses is guaranteed to assure a long lifetime of the circuit inside by avoiding any moisture that could degrade the part. A preferred solution for the enclosure is often stainless steel, as this material resists well to aggressive media. Other solutions such as aluminium and kovar are also possible. One more solution for hermetic seal with ceramic parts can be a glass-seal, which is cured at higher temperatures (400-600°C) to assure under extreme temperatures also a reliable interconnection. Typically, this is done to build economical and reliable pressure sensors or to seal a ceramic cap onto a substrate.

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