Abstract: A stem includes a base member and a block member. The base member includes a main body portion and a columnar portion that rises from one surface of the main body portion. The block member incudes a device mounting surface, on which a semiconductor device is able to be mounted, and is fixed to the one surface of the main body portion in a state in which the block member is pressed against the columnar portion.

Abstract: A stem for a semiconductor package includes an eyelet including a flat plate having a first surface and a second surface opposite to the first surface, a cavity opening to the first surface of the flat plate, and a metal block protruding from the second surface of the flat plate, and a lead extending through the flat plate from the first surface to the second surface, wherein a volume of the metal block is substantially the same as a volume of the cavity.

Abstract: A header for a semiconductor package, includes an eyelet having a through hole penetrating the eyelet from an upper surface to a lower surface of the eyelet, a first lead inserted inside the through hole, and an insulating substrate disposed on the upper surface of the eyelet, and provided with a first through hole at a position overlapping one end of the first lead in a plan view. The insulating substrate has a thermal conductivity lower than a thermal conductivity of the first lead. A first conductive layer is formed on an inner wall defining the first through hole, and the first conductive layer extends to an upper surface of the insulating substrate. The one end of the first lead is electrically connected to the first conductive layer, and a space is provided above the one end of the first lead inside the first through hole.

Abstract: A stem for a semiconductor package includes an eyelet having a through hole formed therethrough, a lead extending through the through hole, and a sealing part configured to seal the through hole around the lead, wherein a main material of the eyelet is 45% Ni—Fe, and wherein a thermal expansion coefficient of the eyelet is greater than a thermal expansion coefficient of the sealing part.

Abstract: A stem includes a base member that includes a main body, a raised portion raised from the top surface of the main body, and a through-hole through the main body, a lead that is inserted into the through-hole of the base member and is fixed to the through-hole with a fixing material such that one end of the lead juts out of the top surface of the main body of the base member, and a substrate that is inserted into a gap between the raised portion of the base member and one end of the lead and is attached to the raised portion to be electrically connected to the one end. The lead has a curved surface curving in a direction widening the gap into which the substrate is inserted, or an inclined surface inclined in a direction widening the gap, on a tip of the one end.

Abstract: A stem includes a base member that includes a main body, a raised portion raised from the top surface of the main body, and a through-hole through the main body, a lead that is inserted into the through-hole of the base member and is fixed to the through-hole with a fixing material such that one end of the lead juts out of the top surface of the main body of the base member, and a substrate that is inserted into a gap between the raised portion of the base member and one end of the lead and is attached to the raised portion to be electrically connected to the one end. The lead has a curved surface curving in a direction widening the gap into which the substrate is inserted, or an inclined surface inclined in a direction widening the gap, on a tip of the one end.

Abstract: A package for an optical semiconductor device includes an eyelet, a signal lead inserted in a through hole formed in the eyelet, and sealing glass sealing the signal lead in the through hole. The signal lead includes a first portion, a second portion and a third portion that are greater in diameter than the first portion and on opposite sides of the first portion, a first tapered portion extending from the second portion to the first portion, and a second tapered portion extending from the third portion to the first portion. The first portion and the first and second tapered portions are buried in the sealing glass. The total length of a part of the second portion in the sealing glass and a part of the third portion in the sealing glass is 0.2 mm or less.

Abstract: A package for an optical semiconductor device includes an eyelet, a signal lead inserted in a through hole formed in the eyelet, and sealing glass sealing the signal lead in the through hole. The signal lead includes a first portion, a second portion and a third portion that are greater in diameter than the first portion and on opposite sides of the first portion, a first tapered portion extending from the second portion to the first portion, and a second tapered portion extending from the third portion to the first portion. The first portion and the first and second tapered portions are buried in the sealing glass. The total length of a part of the second portion in the sealing glass and a part of the third portion in the sealing glass is 0.2 mm or less.

Abstract: A semiconductor device header is provided with a base including a main body and a heat sink. A lead is inserted through a through hole extending through the main body. The is defined by a first opening and a second opening that opens in the upper surface of the main body. The second opening is in communication with the first opening and is smaller than the first opening in a plan view. The first opening is filled with an encapsulant that seals the lead. The second opening is filled with a covering material having a smaller relative permittivity than the encapsulant. The heat sink is located at a position partially overlapped with the first opening in a plan view and separated from the second opening in a plan view.