Electronic device including housing and method for manufacturing the housing

An electronic device comprising:

• a front plate;
• a rear plate facing away the front plate;
• a side member disposed to surround a space defined between the front plate and the rear plate, wherein the side member is coupled to the front plate and the rear plate to define a housing, wherein the side member is at least partially made of a metallic material, and wherein the side member comprises:
• a first surface facing the front plate,
• a second surface facing the rear plate, and
• a trench defined in the second surface and facing the first surface;
• a polymer structure located in the space, wherein the polymer structure defines at least a portion of a sidewall defining the trench, wherein the polymer structure is disposed on the first surface of the side member and includes a polymer material;
• a mechanical button structure disposed in the side member and disposed away from the polymer structure;
• and
• a display arranged in the space to be viewable through the front plate,
• wherein the rear plate is seated on the second surface.