Liquid ejection head and method of manufacturing liquid ejection head

A liquid ejection head comprising:

• a housing;
• an element substrate that is disposed on a first surface of the housing and comprises an energy generation element to eject a liquid, the element substrate including a first side surface and a second side surface;
• a relay wiring member disposed on a second surface of the housing that is positioned downstream of the first surface of the housing in a liquid ejection direction in which the liquid is ejected from the element substrate, the relay wiring member surrounding the element substrate as viewed along the liquid ejection direction;
• a lead that electrically connects the element substrate with the relay wiring member;
• a space including (i) a flow-in portion that is adjacent to the lead and at least a part of which is positioned upstream of the lead with respect to the liquid ejection direction and between the housing and the first side surface of the element substrate, and (ii) a connection portion, at least a part of which is positioned between the housing and the second side surface of the element substrate, the connection portion being connected with the flow-in portion;
• and
• a sealant provided in the flow-in portion and the connection portion of the space,
• wherein, as measured in a direction parallel to both the first surface of the housing and the first side surface of the element substrate, the connection portion has (i) a first width at a first position in the liquid ejection direction, and (ii) a second width at a second position that is upstream of the first position with respect to the liquid ejection direction, the first width being shorter than the second width.