In an embodiment, the second portion 232 of the polymer part 230 may be formed on areas around the openings 250-1 and 250-2. For example, the second portion 232 of the polymer part 230 may include portion 2-1 232-1 formed adjacent to the first end portion (e.g., the end portion facing the—Y-axis direction) of the first opening 250-1, portion 2-2 232-2 formed adjacent to the second end portion (e.g., the end portion facing the Y-axis direction) of the second opening 250-2, and portion 2-3 232-3 extending from portion 2-1 232-1 to portion 2-2 232-2. In various embodiments, portion 2-1 232-1, portion 2-2 232-2, and portion 2-3 232-3 may extend along the peripheries of an inner surface of the first opening 250-1 and an inner surface of the second opening 250-2. However, the position of the second portion 232 of the polymer part 230 is not limited to that illustrated in