Piezoelectric resonator unit

A piezoelectric resonator unit comprising:

• a first enclosure portion that includes a first principal surface portion and a substantially curtain-shaped portion which cooperate to define a recessed portion, the first principal surface portion having a first flat principal surface, the substantially curtain-shaped portion surrounding the first flat principal surface when viewed from a normal direction to the first flat principal surface;
• a second enclosure portion that cooperates with the recessed portion to define an enclosure;
• a brazing material that joins a distal end of the first enclosure portion to the second enclosure portion to hermetically seal the enclosure;
• and
• a piezoelectric resonator that is accommodated in the enclosure;
• wherein an inner peripheral surface of the substantially curtain-shaped portion includes a stepped portion including a thicker portion and a thinner portion as measured in a direction parallel to the first principal surface portion, the thinner portion being located at a position that is remote from the distal end of the substantially curtain-shaped portion, the thicker portion being located adjacent the distal end of the substantially curtain-shaped portion.