Packaging unit and transportation container

A packaging unit that packs storing objects into a box-shaped container, the storing objects being cases storing semiconductor wafers and being arranged in two rows spaced from each other in a width direction and in double deck in a vertical direction in the container, the packaging unit comprising:

• a lower cushioning material configured to support lower parts of the storing objects in the two rows in a lower deck;
• middle cushioning materials, each one of the middle cushioning materials being interposed between the storing objects in corresponding one of the two rows in an upper deck and the storing objects in corresponding one of the two rows in the lower deck;
• upper cushioning materials, each one of the upper cushioning materials being provided on the storing objects in corresponding one of the two rows in the upper deck and configured to hold upper parts of the storing objects in the corresponding one of the two rows;
• and
• a vibration absorbing unit provided on a bottommost portion of the container, the vibration absorbing unit being configured to support the lower cushioning material from below, wherein
• the vibration absorbing unit comprises:
• a first flat plate;
• a second flat plate provided below the first flat plate to be parallel to the first flat plate;
• and
• elastic bodies interposed between the first flat plate and the second flat plate, the number of the elastic bodies being the same as the number of the storing objects in each of the decks, and
• wherein:
• the elastic bodies are provided in positions corresponding to the storing objects arranged in the box-shaped container,
• each elastic body is arranged at a planar position corresponding to a respective one of the storing objects,
• a center of each elastic body is positioned substantially at a center position of the corresponding storing object in a row direction,
• and wherein the center of each elastic body is displaced outward from a center position of the corresponding storing object in a width direction with respect to a centerline between the two rows and a distance between the center of each of the elastic bodies and a centroid of the corresponding one of the storing objects in the width direction is in a range from 2% to 8% of a maximum outer diameter of each of the elastic bodies.