Packaging unit and transport container

Abstract

To suppress a tilting of stored objects and to stably take out the stored objects and a cushioning material.SOLUTION: There is provided a packaging unit 10 for packaging stored objects 80A into a box-shaped container 200 in two rows spaced apart in a width direction and in two tiers in a vertical direction, the packaging unit including: a lower cushioning material 1 that supports two rows of the storage objects 80A in a lower tier, and a middle cushioning material 3 that is interposed between each of the storage objects in upper and lower tiers; an upper cushioning material 5 that holds an upper part of the stored object; and a vibration absorption unit 20 installed at a bottom of the container, the vibration absorption unit 20 including a first flat plate 21, a second flat plate 22, and an elastic body 23 disposed between the first flat plate 21 and the second flat plate 22, in which a center of the elastic body 23 is outside a center of gravity of the stored objects, relative to the middle of the two rows of the stored objects, and a distance D in a width direction between the center of the elastic body 23 and the center of gravity of the stored object is 2% or more of a maximum outer diameter of the elastic body 23 and 8% or less of a maximum outer diameter of the elastic body 23.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a packaging unit for packing an object to be stored in a container and a transport container.

Background Art

[0002] In recent years, the requirements for the quality of semiconductor wafers have become strict, and problems such as scratches on semiconductor wafers caused by vibration and impact during transportation and adhesion of resin materials used for wafer fixing parts have become issues. As a method of transporting semiconductor wafers, a method is known in which a plurality of storage containers storing semiconductor wafers are prepared, these plurality of storage containers are packed in a container, and then the container is transported by a transport device.

[0003] Thus, in order to pack a storage container in a container, there is known one having a cushioning material interposed between the container and the storage container and a vibration absorption unit installed under the cushioning material (referred to as a packaging unit). The cushioning material is mainly formed of foamed polyurethane or the like, and the vibration absorption unit is known to have a configuration including a pair of plastic plates and a plurality of elastic bodies sandwiched between the pair of plastic plates.

[0004] This vibration absorption unit is a unit that suppresses vibration of the storage container during transportation by an elastic body. For example, Patent Document 1 describes a unit constituted by a pair of synthetic resin corrugated papers and an elastic body sandwiched between the pair of synthetic resin corrugated papers.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Incidentally, the elastic body that constitutes the vibration absorption unit has the function of absorbing vibration and impact by elastically deforming. However, depending on the position of the elastic body, the plastic plate may bend significantly, and accordingly, phenomena such as the storage container tilting or the cushioning materials coming into contact with each other may occur. Regarding the number of elastic bodies, although the deflection of the plastic plate can be suppressed by arranging many of them, on the other hand, since the effect of absorbing vibration and impact decreases, it is necessary to arrange them to the minimum necessary extent.

[0007] In particular, in the case of a configuration where the storage containers are arranged to be stacked in two levels vertically in the container, there is a problem that the upper storage container is more significantly inclined than the lower storage container. Also, a problem has occurred in that the interval between the cushioning material and the container has widened, and the cushioning effect at the time of impact during transportation has decreased.

[0008] An object of the present invention is to suppress the inclination of an object to be stored and to stably take out the object to be stored and the cushioning material in a packaging unit for packing an object to be stored in a container and a transport container in which the packaging unit is accommodated in the container.

Means for Solving the Problems

[0009] The packaging unit of the present invention is a packaging unit for packaging an object to be stored, which is a container containing a semiconductor wafer, in a box-shaped container in two rows with a space in the width direction and in two stages in the vertical direction. The packaging unit includes a lower cushioning material that supports the lower portions of the two rows of the objects to be stored in the lower stage, a middle cushioning material that is interposed one by one between the upper and lower objects to be stored in each row of the objects to be stored, an upper cushioning material that is arranged one by one in each row of the two rows of the objects to be stored in the upper stage and holds the upper portions of the objects to be stored, and a vibration absorption unit that supports the lower cushioning material from below and is installed at the bottom of the container. The vibration absorption unit has a first flat plate, a second flat plate that is parallel to the first flat plate and is arranged below the first flat plate, and elastic bodies that are arranged between the first flat plate and the second flat plate and have the same number as the objects to be stored in each stage. In a plan view, the center of the elastic body is outside the middle of the two rows of the objects to be stored with respect to the center of gravity of the objects to be stored, and the distance in the width direction between the center of the elastic body and the center of gravity of the objects to be stored is 2% or more and 8% or less of the maximum outer diameter of the elastic body.

[0010] In the above packaging unit, when the distance between the centers of the adjacent elastic bodies in the column direction is Gx and the distance between the centers of the adjacent elastic bodies in the width direction is Gy, the ratio Gy / Gx of Gy to Gx may be 1 or more and 1.3 or less.

[0011] In the above packaging unit, the bending strength of the first flat plate may be 2 times or more and 3 times or less the bending strength of the second flat plate.

[0012] In the above packaging unit, at least the first flat plate may have a notch formed therein among the first flat plate and the second flat plate.

[0013] The transport container of the present invention is characterized by including the above packaging unit and a box-shaped container that houses the packaging unit.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Mode for Carrying Out the Invention

[0015] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The packing unit 10 of the present invention is a unit for packing a plurality of storage containers 80 in a container 200. A configuration including the packing unit 10 and a box-shaped container 200 in which the packing unit 10 is accommodated is called a transport container 200A. The storage container 80 stores a plurality of semiconductor wafers W. Hereinafter, the storage container 80 in which the semiconductor wafers W are stored is referred to as a storage object 80A.

[0016] The packaging unit 10 includes a cushioning material group 100 composed of an upper cushioning material 5, a middle cushioning material 3, and a lower cushioning material 1, and a vibration absorption unit 20 that supports the lower cushioning material 1 from below and is installed at the bottommost part of the container 200. The cushioning material group 100 is disposed between a plurality of storage objects 80A and the container 200 when the storage object 80A is packaged in the container 200.

[0017] First, the container 200 in which a plurality of storage objects 80A are packaged will be described. As shown in FIG. 1, the container 200 has a rectangular parallelepiped-shaped storage space and is a box for packaging a plurality (12 in this embodiment) of storage objects 80A together with the cushioning material group 100.

[0018] The container 200 includes a container body 201 with an open top surface and a container lid 204 that closes the top surface of the container body 201, and the container body 201 and the container lid 204 together form a box shape as a whole. The container body 201 is composed of four side plates 203 that are connected to each other to form a rectangular tube shape and a bottom plate 202 that closes the bottom. The container 200 can be formed of a material that can withstand transportation by a truck or the like, such as cardboard, plastic, a metal such as aluminum, or wood.

[0019] Next, the arrangement of the cushioning material group 100 and the storage object 80A will be described. As shown in FIGS. 1 to 3, rows in which three storage objects 80A are arranged are arranged in two horizontal rows and two vertical rows, and a total of 12 storage objects 80A are arranged in the container 200. That is, the packaging unit 10 packages the storage object 80A in the container 200 in two rows with a gap in the width direction and two stages in the vertical direction. The number of the objects 80A to be stored in the column of the objects 80A to be stored is not limited to this. For example, two columns in which two objects 80A are arranged may be arranged in two rows vertically. In the following description, the direction in which the column of the objects 80A to be stored extends is referred to as the X direction (column direction), the direction orthogonal to the X direction is referred to as the Y direction (width direction), and the vertical direction is referred to as the Z direction.

[0020] The buffer material group 100 buffer-stores these two columns and two rows of the objects 80A to be stored. The buffer material group 100 includes one lower buffer material 1 that supports the lower parts of the two columns of the objects 80A in the lower row, middle buffer materials 3 that are respectively interposed between the upper row of the objects 80A and the lower row of the objects 80A in each column of the objects 80A to be stored, and upper buffer materials 5 that are respectively arranged in each column of the two columns of the objects 80A in the upper row and hold the upper parts of the objects 80A to be stored. In the following description, the state in which twelve objects 80A to be stored, two upper buffer materials 5, two middle buffer materials 3, and one lower buffer material 1 are arranged in the container 200 is referred to as the packaging state.

[0021] Next, the storage container 80 that constitutes the object 80A to be stored will be described. The storage container 80 is a container for storing the semiconductor wafer W, and is, for example, a FOSB (Front Opening Shipping Box). As shown in FIG. 4, the storage container 80 has a container body 81 that is open at the top and a container lid 82 that closes the top of the container body 81. The container body 81 integrally includes a pair of first wall portions 83, a pair of second wall portions 84 that form the side surface of the container body 81 together with the pair of first wall portions 83, and a bottom portion 85 that closes the bottom of the container body 81. The container body 81 includes a plurality of leg portions 86. The leg portions 86 are legs that protrude downward from the bottom portion 85.

[0022] As shown in FIG. 2, in the container body 81 of the storage container 80, a comb-shaped wafer storage portion 87 in which storage grooves for storing a plurality of semiconductor wafers W at intervals are formed is provided. The wafer storage part 87 is composed of a side storage part 87A that contacts the outer edge side part of the semiconductor wafer W and a bottom storage part 87B that contacts the outer edge bottom part of the semiconductor wafer W.

[0023] The side storage parts 87A are provided in one row each inside the opposing second wall parts 84. Two bottom storage parts 87B are provided directly above the bottom 85. The two side storage parts 87A are arranged parallel to each other in the groove arrangement direction, that is, the direction perpendicular to the plane of FIG. 2, in each second wall part 84.

[0024] The container lid 82 is a plate-shaped member with a rectangular planar shape and has a pair of lock parts 89 on the front surface side and a holding part 91 on the back surface (inner surface) side as shown in FIGS. 4 and 5. The lock part 89 is a member for fixing the container lid 82 to the container body 81 and has lock bars 89A, 89B and a latch mechanism 89C as shown in FIG. 5(A). The lock bars 89A, 89B are members provided along the opposing sides of the container lid 82 and can move in the direction of FIG. 5 L1, L2 and are movable.

[0025] By rotating the latch mechanism 89C, the lock bar 89A can be operated in the L1 direction and the lock bar 89B can be operated in the L2 direction by a cam mechanism. As a result, the tips of the lock bars 89A, 89B engage with the recess 81A of the container body 81, and the container lid 82 is fixed to the container body 81. By returning the position of the latch mechanism 89C to its original position with the container lid 82 fixed to the container body 81, the lock bars 89A, 89B are pulled back inside the container lid 82, and the fixation of the container body 81 is released.

[0026] As shown in FIG. 5(B), the holding part 91 is a vertically long comb-shaped member provided on the back surface side of the container lid 82 and is provided between the lock parts 89. The holding part 91 regulates the axial movement or radial rotation of the semiconductor wafers W by inserting and abutting the upper peripheral edges of the semiconductor wafers W accommodated in the container body 81 between the teeth of the comb, and holds the semiconductor wafers W so that they do not contact each other. In FIG. 5(B), the holding portion 91 is provided in the central portion of the container lid 82 parallel to the array direction of the semiconductor wafers W so as to be parallel to one of the sides constituting the rectangle of the container lid 82.

[0027] Next, the cushioning materials 1, 3, and 5 that make up the cushioning material group 100 will be described. The cushioning materials 1, 3, and 5 are each made of any one of polyurethane foam, polyethylene foam, polypropylene foam, or polystyrene foam. The lower cushioning material 1 that makes up the cushioning material group 100 is a cushioning material that supports the lower part of the storage object 80A in the row of the lower-stage storage objects 80A. The lower cushioning material 1 has a rectangular shape. The lower cushioning material 1 is formed so as to cover substantially the entire bottom plate 202 of the container 200. The lower cushioning material 1 has six lower storage portions 11 in which the lower part of the storage container 80 is stored. Three lower storage portions 11 are formed in the X direction and two lower storage portions 11 are formed in the Y direction.

[0028] The lower storage portion 11 is a portion having a shape into which the lower part of the storage container 80 fits. In the center of the lower storage portion 11, a lower opening 12, which is a rectangular hole formed in the bottom surface of the lower cushioning material 1, is formed.

[0029] The upper cushioning material 5 that makes up the cushioning material group 100 is a cushioning material that holds the upper part of the storage object 80A in the row of the upper-stage storage objects 80A. The upper cushioning material 5 has a rectangular shape. The upper cushioning materials 5 are used in pairs of two in the packed state, and each upper cushioning material 5 is formed so as to cover approximately half of the opening of the container 200.

[0030] The upper cushioning material 5 has three upper storage portions 51. Each upper storage portion 51 holds the container lid 82 of the storage container 80.

[0031] As shown in FIGS. 1 and 2, two upper cushioning materials 5 are arranged side by side and stored in the container body 201 in the packed state. In the upper storage portion 51, at the center of the upper storage portion 51, an upper opening portion 52, which is a rectangular hole penetrating between the upper surface and the lower surface of the upper cushioning material 5, is formed.

[0032] The middle cushioning material 3 is a cushioning material that holds the upper part of the object to be stored 80A in the row of the objects to be stored 80A in the lower stage and supports the lower part of the object to be stored 80A in the row of the storage containers 80 in the upper stage. The middle cushioning material 3 has a rectangular shape. Similar to the upper cushioning material 5, the middle cushioning material 3 is used in pairs of two in the packaged state. On the upper surface of the middle cushioning material 3 (the surface facing upward in the packaged state), three middle main body storage portions 31 similar to the lower storage portion 11 of the lower cushioning material 1 are formed. On the lower surface of the middle cushioning material 3 (the surface facing downward in the packaged state), a middle lid storage portion 41 similar to the upper storage portion 51 of the upper cushioning material 5 is formed.

[0033] The position of the object to be stored 80A in the packaged state is determined by the shape of the cushioning material. The objects to be stored 80A are symmetrically arranged with respect to the center CL in the Y direction.

[0034] Next, with reference to FIGS. 2 and 3, the structure of the vibration absorption unit 20 will be described. The vibration absorption unit 20 is a unit that absorbs vibrations generated when packaging the object to be stored 80A, and includes a first flat plate 21, a second flat plate 22, and a plurality of elastic bodies 23. The vibration absorption unit 20 is disposed between the lower cushioning material 1 and the bottom plate 202 of the container 200.

[0035] The first flat plate 21 and the second flat plate 22 are rectangular plate-like members that are slightly smaller than the bottom plate 202 of the container 200. The second flat plate 22 is disposed on the bottom plate 202 of the container 200, and the first flat plate 21 is disposed on the second flat plate 22 via a plurality of elastic bodies 23. The second flat plate 22 is parallel to the first flat plate 21 and is disposed below the first flat plate 21. The elastic bodies 23 are disposed so as to be sandwiched between the first flat plate 21 and the second flat plate 22.

[0036] The first flat plate 21 and the second flat plate 22 are preferably plastic plates with a thickness of 3 mm or more and 25 mm or less, and more preferably plastic plates with a thickness of 8 mm or more and 20 mm or less. The first flat plate 21 and the second flat plate 22 are preferably formed of plates with a hollow structure made of plastic, such as plastic corrugated cardboard. The first flat plate 21 and the second flat plate 22 are not limited to plastic plates, and other plate-like members that are lightweight and excellent in vibration absorption can be adopted.

[0037] As shown in FIG. 7, notches 24 are formed in the first flat plate 21 and the second flat plate 22. The notch 24 of the present embodiment is formed substantially at the center in the X direction of the long side of the flat plates 21 and 22. The notch 24 may be formed on the short side of the flat plates 21 and 22. The shape of the notch 24 is preferably a semi-circular shape, but may also be a rectangular shape or the like.

[0038] In the present embodiment, the notches 24 are formed in the first flat plate 21 and the second flat plate 22, but the present invention is not limited thereto, and at least the first flat plate 21 may have the notch 24 formed therein among the first flat plate 21 and the second flat plate 22.

[0039] The bending strength of the first flat plate 21 is 2 times or more and 3 times or less the bending strength of the second flat plate 22. The first flat plate 21 of the present embodiment can be formed of a plastic plate with a bending strength of 2 MPa or more and 8 MPa or less. The second flat plate 22 of the present embodiment can be formed of a plastic plate with a bending strength of 1 MPa or more and 4 MPa or less. The thickness of the first flat plate 21 and the thickness of the second flat plate 22 are the same, and different bending strengths are obtained by using plastic plates of different materials.

[0040] Note that the first flat plate 21 and the second flat plate 22 may be plastic plates of the same material, and the bending strength of the first flat plate 21 may be 2 times or more and 3 times or less the bending strength of the second flat plate 22 by making the thickness of the first flat plate 21 thicker than the thickness of the second flat plate 22.

[0041] The elastic body 23 is a member that has a cylindrical shape and absorbs vibration by elastically deforming against vibration. The diameter of the elastic body 23 is 45 mm or more and 85 mm or less. The height of the elastic body 23 is 25 mm or more and 35 mm or less. The elastic body 23 can be formed of, for example, polyurethane resin, synthetic rubber, polyethylene, etc., but it is preferably formed of polyurethane resin. The upper and lower surfaces of the elastic body 23 are adhered to the flat plates 21 and 22. The number of the elastic bodies 23 is the same as the number (6) of the storage objects 80A in each stage.

[0042] Next, the details of the position where the elastic body 23 is arranged will be described. FIG. 6 is a cross-sectional view of the vibration absorption unit 20, and FIG. 7 is a plan view of the vibration absorption unit. As shown in FIGS. 6 and 7, each elastic body 23 is arranged between a pair of flat plates 21 and 22 at a position corresponding to the storage object 80A (in a plan view, at substantially the same position as the storage object 80A). That is, the elastic body 23 is arranged symmetrically with respect to the center CL in the Y direction, similarly to the storage object 80A. The position of the center C1 of the elastic body 23 in the X direction is substantially the same as the position of the center of gravity C2 of the storage object 80A in the X direction.

[0043] In a plan view, the position of the center C1 of the elastic body 23 in the Y direction is not the same as the position of the center of gravity C2 of the storage object 80A. The center C1 of the elastic body 23 is outside with respect to the middle of the two rows of storage objects 80A, compared to the center of gravity C2 of the storage object 80A. That the center C1 of the elastic body 23 is outside the center of gravity C2 of the storage object 80A means that the distance D1 between the center CL in the Y direction and the center C1 of the elastic body 23 is larger than the distance D2 between the center CL in the Y direction and the center of gravity C2 of the storage object 80A.

[0044] When viewed from the column direction (X direction), the distance D in the Y direction (horizontal direction) between the center C1 of the elastic body 23 and the center of gravity C2 of the object 80A to be stored is 2% or more and 8% or less of the diameter of the elastic body 23. When the diameter of the elastic body 23 is 65 mm, the horizontal distance between the center of the elastic body 23 and the center of gravity of the object 80A to be stored is about 1.3 mm or more and 5.2 mm or less. When the elastic body 23 is cylindrical, the diameter of the elastic body 23 is the maximum outer diameter of the elastic body 23.

[0045] In addition, when the elastic body 23 is not cylindrical but has a polygonal cross-section, the horizontal distance between the center of the elastic body 23 and the center of gravity of the object 80A to be stored is 2% or more and 8% or less of the maximum outer diameter of the elastic body 23. The maximum outer diameter is the diameter of the circumscribed circle of the polygon.

[0046] Also, if the interval between adjacent elastic bodies in the X direction is Gx and the interval between adjacent elastic bodies in the Y direction is Gy, the ratio Gy / Gx of Gy to Gx is in the range of 1 or more and 1.3 or less.

[0047] 〔Optimization of the position and number of elastic bodies, bending strength of flat plates, etc.〕 Next, an analysis performed to optimize the position and number of the elastic bodies 23, the bending strength of the flat plates 21 and 22, and the ratio Gy / Gx of the interval Gy between adjacent elastic bodies in the Y direction to the interval Gx between adjacent elastic bodies in the X direction will be described.

[0048] 〔Examination of the position and number of elastic bodies〕 The inventors considered that the position of the elastic body 23 affects the deflection of the first flat plate 21 and the inclination of the object 80A to be stored. In particular, since the upper buffer material 5 and the middle buffer material 3 are divided in the Y direction, it is considered that the position of the elastic body 23 in the Y direction greatly affects the deflection of the first flat plate 21 and the inclination of the object 80A to be stored. The position of the elastic body 23 was changed in the Y direction, and the displacement amount (deflection amount) of the first flat plate 21 was analyzed. The position of the elastic body 23 was changed in the Y direction with the center of gravity C2 of the object 80A to be stored as a reference. The position of the elastic body 23 in the X direction was the same as the position of the object 80A to be stored in the X direction and was not changed. Also, the diameter of the elastic body 23 was set to 65 mm.

[0049] Also, in order to examine the number of elastic bodies 23, as shown in FIG. 8, two elastic bodies 23 were added to the center CL in the Y direction, and analysis was also performed when the number of elastic bodies 23 was eight.

[0050] FIG. 9 is a graph showing the displacement amount of the first flat plate 21 when the position of the elastic body 23 in the Y direction is changed when six elastic bodies 23 are arranged as shown in FIG. 7. The horizontal axis of FIG. 9 is the position (mm) in the Y direction on the first flat plate 21, and the vertical axis is the displacement amount in the vertical direction of the first flat plate 21. Note that 0 mm in the Y direction is the left end LS in FIG. 7, and 950 mm in the Y direction is the right end RS in FIG. 7. As shown in FIG. 9, when the distance D between the center C1 of the elastic body 23 and the centroid C2 of the object 80A to be stored was 5 mm, the displacement amount of the first flat plate 21 became the smallest. That is, when the position of the center C1 of the elastic body 23 was 5 mm outside the position of the centroid C2 of the object 80A to be stored, the amount of deflection of the first flat plate 21 was the smallest.

[0051] Since the diameter of the elastic body 23 is 65 mm, even if the position of the center C1 of the elastic body 23 is 5 mm outside the position of the centroid C2 of the object 80A to be stored, since the elastic body 23 exists directly below the centroid C2 of the object 80A to be stored, it is considered that the first flat plate 21 is stably supported.

[0052] On the other hand, when the distance D was 44.5 mm, the amount of deflection of the first flat plate 21 became the largest. Since the diameter of the elastic body 23 is 65 mm, the elastic body 23 no longer exists directly below the centroid C2 of the object 80A to be stored, so it is considered that the first flat plate 21 is likely to deflect. Specifically, as the distance D increased to 9.9 mm, 19.9 mm, 23.9 mm, and 44.5 mm, the deflection of the first flat plate 21 increased.

[0053] Also, when the position of the center C1 of the elastic body 23 is set inside the position of the center of gravity C2 of the object 80A to be stored, when the distance D is -0.1 mm, that is, when the elastic body 23 exists directly below the center of gravity C2 of the object 80A to be stored, compared with the case where the distance D is 5 mm, the result is that the deflection becomes larger. When the distance D is -2.5 mm, and when the distance D is -5.1 mm, the deflection becomes even larger.

[0054] FIG. 10 is a graph showing the displacement amount of the first flat plate 21 when the position of the elastic body 23 in the Y direction is changed when eight elastic bodies 23 are arranged as shown in FIG. 8. The horizontal axis of FIG. 10 is the position (mm) in the Y direction on the first flat plate 21, and the vertical axis is the displacement amount in the vertical direction of the first flat plate 21.

[0055] As shown in FIG. 10, when the distance D between the center C1 of the elastic body 23 and the center of gravity C2 of the object 80A to be stored is 53 mm, the displacement amount of the first flat plate 21 becomes the smallest. By arranging two elastic bodies 23 at the center CL in the Y direction, it is considered that the first flat plate 21 is less likely to deflect even when the elastic body 23 does not exist directly below the center of gravity C2 of the object 80A to be stored.

[0056] According to the above analysis, when six elastic bodies 23 are arranged, the optimal distance D between the center C1 of the elastic body 23 and the center of gravity C2 of the object 80A to be stored is 5 mm, and when eight elastic bodies 23 are arranged, the optimal distance D is 53 mm.

[0057] Next, in order to examine the number of elastic bodies 23, a container 200 in which the object 80A to be stored and the packaging unit 10 are set was fixed on a vibration testing machine, vibration sensors were attached to predetermined positions of the storage container, the pallet, and the vibration table, and a vibration test was conducted. The vibration frequency was 5 to 500 Hz, the vibration condition was 0.5 G, and the vibration time was 5 minutes.

[0058] Figure 11 shows the results of the vibration test, which is a graph representing the results of the vibration test under Condition 1 where the number of elastic bodies 23 is 6 and the distance D is 44.5 mm, Condition 2 where the number of elastic bodies 23 is 6 and the distance D is 5 mm, and Condition 3 where the number of elastic bodies 23 is 8 and the distance D is 53 mm. In the vibration test, excitation was applied in the Z direction, and the vibration intensity in the Z direction in the storage container was compared. The "lower part" in Figure 11 is the vibration intensity detected in the lower storage container, and the "upper part" is the vibration intensity detected in the upper storage container.

[0059] As shown in Figure 11, when eight elastic bodies 23 were arranged, even in an arrangement where the displacement amount of the first flat plate 21 could be reduced, the result was that the vibration excitation speed in the Z direction increased. This is presumably because when the number of elastic bodies 23 increased, the rigidity of the entire vibration absorption unit 20 became too high, resulting in a decrease in the vibration absorption ability. As a result, it was concluded that six elastic bodies are preferable. Note that in Condition 1, although the displacement amount was large in the graph showing the displacement amount of the first flat plate 21 in Figure 9, it was confirmed that even when the displacement amount was large, the vibration excitation speed in the Z direction was not greatly affected, and the influence of the number was significant.

[0060] Figure 12 shows the results of the vibration test under Condition 1, Condition 2, and Condition 3, which is a graph comparing the vibration intensity in the X direction in the storage container when excitation was applied in the Z direction.

[0061] As shown in Figure 12, when eight elastic bodies 23 were arranged, even in an arrangement where the displacement amount of the first flat plate 21 could be reduced, particularly the vibration excitation speed in the X direction of the upper part increased. This is also presumably because when the number of elastic bodies 23 increased, the rigidity of the entire vibration absorption unit 20 became too high, resulting in a decrease in the vibration absorption ability. Even with this result, it was concluded that six elastic bodies are preferable. Regarding Condition 1 as well, it was confirmed that the vibration excitation speed in the X direction was not greatly affected, and the influence of the number was significant.

[0062] When six elastic bodies 23 are arranged, when the distance D is expressed as a ratio to the diameter of the elastic body 23, the distance D is optimally 8% of the diameter of the elastic body 23 (≒5 mm / 65 mm), and this was set as the upper limit value. As can be seen from FIG. 9, when the distance D becomes 9.9 mm, the deflection becomes large, so an upper limit value was set to exclude this.

[0063] On the other hand, the lower limit of the distance D was set to 2% of the diameter of the elastic body 23. It is preferable that the center C1 position of the elastic body 23 is outside the position of the center of gravity C2 of the object 80A to be stored, in order to eliminate the possibility that the center C1 position of the elastic body 23 becomes inside the position of the center of gravity C2 of the object 80A due to manufacturing errors. As can be seen from FIG. 9, when the distance D becomes -0.1 mm, the deflection becomes large, so a lower limit value was set to exclude this.

[0064] 〔Examination of the bending strength of the flat plate〕 Next, in order to examine the strength of the flat plate, a vibration test was conducted using two types of first flat plates 21 with different bending strengths. FIG. 13 shows the results of the vibration test. It is a graph showing the results of the vibration test under Condition 2 where the number of elastic bodies 23 is six, the distance D is 5 mm, and the bending strength of the first flat plate is 1.5 Mpa (the same bending strength as the second flat plate), and Condition 4 where the number of elastic bodies 23 is six, the distance D is 5 mm, and the bending strength of the first flat plate is 3 Mpa (twice the bending strength of the second flat plate). In the vibration test, vibration was applied in the Z direction, and the vibration intensity in the X direction in the storage container was compared.

[0065] As shown in FIG. 13, when the bending strength of the first flat plate was twice that of the second flat plate, although the vibration intensity in the upper stage became slightly higher, it was possible to improve the amount of deflection while improving the vibration intensity in the lower stage. As a result, it was concluded that it is preferable to set the bending strength of the first flat plate 21 to be twice that of the second flat plate.

[0066] 〔Optimization of the ratio Gy / Gx of the interval Gy between adjacent elastic bodies in the Y direction and the interval Gx between adjacent elastic bodies in the X direction〕 Regarding the ratio Gy / Gx of the interval Gy between adjacent elastic bodies in the Y direction and the interval Gx between adjacent elastic bodies in the X direction, a vibration analysis model was constructed for the container, the packaging unit, the object to be stored, and the pallet that supports these from below, and optimization was performed by conducting frequency response analysis using finite element analysis software. Specifically, in the frequency response analysis, a sine-wave acceleration with an amplitude of ±0.5G was applied to the pallet that supports the container from below, and the response of each member to external vibration was evaluated by calculating the acceleration. The frequency range was set to 10 Hz to 200 Hz, and the frequency interval was set to 1 Hz.

[0067] The evaluation index was set as the root mean square (RMS) value calculated by the following mathematical formula (1). RMS = √(the mean of the squares of the accelerations at each frequency) ··· (1) In other words, RMS is the square root of the mean of the squares of the accelerations at each frequency. From the analysis results of the vibration experiments on the objects to be stored conducted in the past, it has been found that there is a correlation between the amount of resin adhesion to the wafer edge due to vibration during transportation and RMS.

[0068] FIG. 14 is a graph showing the correlation between the ratio Gy / Gx and RMS. As shown in FIG. 14, it was confirmed that the RMS tends to decrease when the ratio Gy / Gx is 1 or more and 1.3 or less.

[0069] According to the above embodiment, by setting the distance D between the center C1 of the elastic body 23 and the center of gravity C2 of the object to be stored 80A to be 2% or more and 8% or less of the diameter of the elastic body 23, the amount of deflection of the first flat plate 21 can be reduced. As a result, in the packaging unit 10 for packaging the object to be stored 80A in the container 200, the inclination of the object to be stored 80A can be suppressed, and the object to be stored 80A and the cushioning material can be stably taken out.

[0070] Further, assuming that the interval Gx between adjacent elastic bodies in the X direction and the interval Gy between adjacent elastic bodies in the Y direction, by setting the ratio Gy / Gx of Gy to Gx in the range of 1 or more and 1.3 or less, for example, vibrations during transportation of the object 80A to be stored can be suppressed, and the amount of resin adhesion to the wafer edge can be reduced.

[0071] Further, by setting the bending strength of the first flat plate 21 to be 2 times or more and 3 times or less the bending strength of the second flat plate 22, it is possible to reduce the vibration strength when excited.

[0072] Further, by forming the notch 24 in the first flat plate 21 and the second flat plate 22, when taking out the vibration absorption unit 20, it can be taken out using the notch 24. Thereby, the vibration absorption unit 20 can be easily taken out.

[0073] In addition, in the above embodiment, the elastic body 23 is cylindrical, but it is not limited thereto. For example, it may have a prismatic shape such as a rectangular parallelepiped shape, or a frustum shape.

[0074] Further, in the above embodiment, the position of the elastic body 23 in the X direction is substantially the same as the position of the center of gravity C2 of the object 80A to be stored in the X direction, but it is not limited thereto, and it may be displaced in the X direction. However, it is preferable that the elastic body 23 at the center in the X direction is substantially the same as the position of the center of gravity C2 of the object 80A to be stored in the X direction.

[0075] Further, in the above embodiment, the bending strength of the first flat plate 21 is set to be 2 times or more and 3 times or less the bending strength of the second flat plate 22, but it is not limited thereto. If the amount of deflection of the first flat plate 21 can be suppressed by optimizing the position of the elastic body 23, for example, the bending strength of the first flat plate 21 may be the same as the bending strength of the second flat plate 22.

[0076] Further, the lower buffer material is integrated, but like the upper buffer material and the middle buffer material, it may be divided in the width direction. Further, the middle buffer material may be divided in the vertical direction.

Explanation of reference numerals

[0077] 1… Lower buffer material, 3… Middle buffer material, 5… Upper buffer material, 10… Packing unit, 20… Vibration absorption unit, 21… First flat plate, 22… Second flat plate, 23… Elastic body, 80… Storage container, 80A… Object to be stored, 81… Container body, 100… Buffer material group, 200… Container, 200A… Transport container, 201… Container body, 202… Bottom plate, C1… Center, C2… Center of gravity, D… Distance, W… Semiconductor wafer.

Claims

1. A packaging unit for packing an object to be stored, which is a container containing a semiconductor wafer, in a box-shaped container in two rows with a space in the width direction and in two stages in the vertical direction, comprising: a lower cushioning material that supports the lower portions of the two rows of the objects to be stored in the lower stage; a middle cushioning material interposed one by one between the objects to be stored in the upper stage and the objects to be stored in the lower stage in each row of the objects to be stored; an upper cushioning material arranged one by one in each row of the two rows of the objects to be stored in the upper stage to hold the upper portions of the objects to be stored; a vibration absorption unit that supports the lower cushioning material from below and is installed at the bottommost part of the container; The vibration absorption unit includes: a first flat plate; a second flat plate parallel to the first flat plate and arranged below the first flat plate; elastic bodies arranged between the first flat plate and the second flat plate and having the same number as the objects to be stored in each stage; In a plan view, the center of the elastic body is outside the middle of the two rows of the objects to be stored with respect to the center of gravity of the objects to be stored, and the distance in the width direction between the center of the elastic body and the center of gravity of the objects to be stored is 2% or more and 8% or less of the maximum outer diameter of the elastic body. A packaging unit.

2. In the packaging unit according to Claim 1, When the distance between the centers of the adjacent elastic bodies in the column direction is Gx and the distance between the centers of the adjacent elastic bodies in the width direction is Gy, the ratio Gy / Gx of Gy to Gx is 1 or more and 1.3 or less. A packaging unit.

3. In the packaging unit according to Claim 1 or Claim 2, The bending strength of the first flat plate is 2 times or more and 3 times or less the bending strength of the second flat plate. A packaging unit.

4. In the packaging unit according to Claim 1 or Claim 2, Among the first flat plate and the second flat plate, at least the first flat plate has a notch formed therein. A packaging unit.

5. A transport container comprising the packaging unit according to Claim 1 or Claim 2, and a box-shaped container in which the packaging unit is accommodated.

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