Ceramic substrate, preparation method of ceramic substrate, microwave device and packaging shell structure of microwave device

The invention discloses a ceramic substrate and a preparation method thereof, a microwave device and a packaging shell structure thereof. The preparation method of the ceramic substrate comprises the following steps: preparing a ceramic plate of which a signal shielding through hole is filled with a conductor material by adopting an HTCC process, grinding the ceramic plate to a set thickness to serve as the ceramic substrate, and punching a hole in the ceramic substrate to serve as a signal transmission through hole; sequentially sputtering a titanium layer and a palladium layer on the ceramic substrate; then shielding a preset hydrogen absorption region, wherein an unshielded region is an etching region; and copper is plated in the etching region until the signal transmission through hole is filled with the copper conductor, and then a nickel layer and a gold layer are sequentially formed on the plated copper layer in an electroplating or sputtering mode. According to the invention, the hydrogen absorption a