Abstract: A substrate includes: a first insulating layer; a second insulating layer disposed on the first insulating layer; and a via hole including a lower hole formed in the first insulating layer, and an upper hole formed in the second insulating layer and connected to the lower hole, in which a width of an upper side of the lower hole is larger than a width of a lower side of the lower hole, and a width of an upper side of the upper hole is larger than a width of a lower side of the upper hole.

Abstract: A substrate including: an insulation layer; a conductive layer disposed on the insulation layer; and a via hole configured to include a lower hole disposed in a first portion of the insulation layer and an upper hole disposed in a second portion of the insulating layer and connected to the lower hole, wherein a width of the upper hole is greater than that of the lower hole, at least a portion of the upper hole of the insulation layer has a width that is substantially equal to that of the upper hole of the conductive layer, and a first angle formed between a first direction that is parallel to a lower surface of the insulating layer and a sidewall of the lower hole and a second angle formed between the first direction and a sidewall of the upper hole are different from each other.

Abstract: An electronic device includes an antenna board configured for massive MIMO. The antenna board is coupled to a filter board using signal contacts with elasticity and ground contacts with elasticity. The configuration of the signal contacts and the ground contacts permits a satisfactory accumulated tolerance in terms of component precision.

Abstract: Disclosed is a carbon dioxide indicator using chitosan and a food package comprising the same. The carbon dioxide indicator senses variation in partial pressure of carbon dioxide present in a head space of the package and thus visibly displays the result. The carbon dioxide indicator rapidly reacts at a specific critical point (pH 7.0) or less, thus being considerably highly sensitive.