Wafer container with overlapping wall structure
View Patent ↗Improvements in a semiconductor wafer container including improvements in side protection to the wafers, improved cover design to minimize rotation, a simplified top cover orientation mechanism and an improved bottom holding mechanism for automation. The side protection to the wafers is with multiple staggered inner and outer walls. The improved cover design improves alignment of the top and bottom housings and minimizes rotation of the housings in transit or motion. The housings have a recessed tab ramp feature with bi-directional locking that also increases the rigidity of the containment device when the two housings are assembled. The improved bottom holding mechanism for automation is an integrated feature that is molded into the bottom housing and not assembled in a secondary operation. The molded integration reduces tolerance errors that are present in assembling multiple pieces and joining multiple pieces.
1. A wafer container comprising:
a top housing and a bottom housing that nest together to form a clam shell housing with an inner cavity for storage for at least one semiconductor wafer;
said top housing having an essentially planar rectangular base with at least one rib that extends perpendicular from said base in an essentially circular orientation;
said bottom housing having an essentially planar rectangular base with a plurality of inner and outer arc sector ribs that extend perpendicular from said base wherein said inner and outer arc sectors ribs are arranged concentric with said at least one rib that extends perpendicular from said base of said top housing, and
said inner and outer arc sector ribs are formed such that the arc sector of at least one inner rib overlaps the arc sector of at least two outer ribs wherein said overlap of said at least one inner arc sector rib and said at least two outer arc sector ribs is an overlap of between 5 and 15 degrees when measured from a concentric origin of said arc sector ribs.
2. The wafer container according to claim 1 wherein said at least one inner rib and said at least one outer rib extend from said essentially planar rectangular base the same height.
3. The wafer container according to claim 1 wherein said at least one inner arc sector rib and said at least one outer arc sector rib extend from said essentially planar rectangular base different heights.
4. The wafer container according to claim 1 that further includes at least one additional rib that extends from said bottom of said essentially rectangular base that is orthogonal to at least one side of said bottom;
a bi-directional locking feature haying at least one set of locating ribs that extend from said essentially planar base of said bottom housing that locate and capture opposing sides of said at least one additional rib that extends from said bottom of said essentially rectangular base that is orthogonal to at least one side of said bottom, wherein
said locking feature creates a bi-directional lock of said top and said bottom housing to minimize rotation there between.
5. The wafer container according to claim 4 wherein said at least one additional rib that extends from said bottom of said essentially rectangular base that is orthogonal to at least one side of said bottom is U-shaped and is orthogonal to three sides of said bottom.
6. The wafer container according to claim 5 wherein there are four sets of said U-shaped rib.
7. The wafer container according to claim 5 wherein said bi-directional locking feature captures at least two sides of said U-shaped rib.
8. The wafer container according to claim 1 wherein said at least one rib on said top housing has an orientation tab that extends normal to said rib on an outward direction of said circular orientation, and
said at least one rib on said bottom housing is configured to only clear said orientation tab when said top housing and said bottom housing are placed in only one orientation.
9. The wafer container according to claim 8 wherein there are at least four orientation tabs.
10. The wafer container according to claim 8 wherein said orientation tabs prevent improper assembly of said top housing and said bottom housing members from being installed 90 degrees out of alignment.
11. The wafer container according to claim 8 wherein said orientation tab is protectively located adjacent to a U-shaped rib that extends from said essentially circular oriented rib.
12. The wafer container according to claim 1 wherein said bottom housing has an undercut recessed pocket with a latch surface for a retention mechanism wherein said latch surface exists below said wafer supporting wall;
said latch surface being formed in a molding process with the molding of said bottom housing.
13. The wafer container according to claim 12 wherein said latch surface is located at a height that is equal to or lower than the planar bottom surface of said bottom housing.
14. The wafer container according to claim 12 wherein said latch surface further has an angled or curved entry surface.
15. The wafer container according to claim 12 wherein said pocket further has at least two essentially vertical side walls to self-center said bottom housing on said retention mechanism.
16. The wafer container according to claim 1 wherein said bottom housing has at least one latch that engages in a corresponding notch located on said top housing, wherein said at least one latch surface exists below said wafer supporting wall, and
said a top surface of said latch is located at a height that is below a top surface of said at least one rib.
17. The wafer container according to claim 16 wherein said at least one latch includes at least four latches and four corresponding notches located in each corner region of said top housing or said bottom housing.
18. The wafer container according to claim 16 wherein said notch has a curve entry ramp and recess that elevates said latch above said entry ramp and lowers said latch into said recess to retain said latch in said recess when normal forces are applied to said top housing and said bottom housing.
19. The wafer container according to claim 16 wherein said notch is located in a pocket that protects said latch during handling and impact.
20. The wafer container according to claim 1 wherein said bottom housing having an outer annular lip;
said top housing having an outer annular lip that is configured to nest and fit within said outer annular lip of said bottom housing, and
said bottom housing further having a plurality of bearing ribs that extend from said essentially rectangular base to support said annular lip on said top housing.
21. The wafer container according to claim 20 wherein said plurality of bearing ribs exist in at least four per quadrant on said bottom housing.
22. The wafer container according to claim 20 wherein said plurality of bearing ribs create a bearing surface of at least 2.25 mm 2 .
23. The wafer container according to claim 20 wherein said plurality of bearing ribs reduce damage to at least one of stacking pads and the top rim of the housings.