Alkali-free glasses are disclosed having (in weight %) 50SiO.sub.280%, 2Al.sub.2O.sub.317%, 8B.sub.2O.sub.336%, and greater than or equal to 2% and less than or equal to 25% of at least one of CaO, MgO, BaO, SrO or ZnO. The alkali-free glasses can have a surface layer with greater than 0.2 weight % N. Such alkali-free glasses are achieved by nitriding processes and exhibit increased strength, scratch resistance and chemical durability.

According to the present disclosure, a substrate comprises a glass core. The glass core comprises a through via penetrating the glass core in a thickness direction. A diameter of the through via is 50 m to 100 m. A sum of a sulfur content (atomic %) and a nitrogen content (atomic %) of the glass core is 0.2 atomic % to 8 atomic %.

In this case, it may be possible to provide a substrate that achieves more stable electrical connection through the glass core and exhibits stable durability and electrical reliability even under a high-humidity environment.