This article deals with usage of low-temperature co-fired ceramic as a material for hermetic package of bare-dies. Two types of substrates are measured -Heraeus HeraLock2000 and DuPont GreenTape 951PT. For more accurate results, different arrays of vias are designed to imitate conductive joints in a package. An air-tightness of samples is determined based on Oxygen Transmission Rate measurement. Dependence of the air-tightness on a material thickness and on a count of vias was investigated. Design and fabrication of the samples and measurement description is also included. Results of this experiment compare mentioned types of ceramics and create a base of knowledge for design of an air-tight package.