Wafer retaining mechanism

Disclosed is a wafer retaining mechanism comprising a box, and more than one link unit affixed to appropriate locations of the box, the link units being operative in coordination with a wafer cassette and a chassis for retaining securely the wafers received within the cassette. The links each comprises a sliding link, a lower link, a front link, an upper link, and associated pins.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a wafer retaining mechanism, in particular 
to one including more than one link unit each of which has a sliding link, 
a lower link, a front link, an upper link, and associated pins, thereby 
the link units can urge, and retain securely, the wafers contained in a 
wafer cassette. 
2. Description of the Prior Art 
Conventionally various devices are provided for preventing the 
semiconductor wafers from being jarred or bumped when the wafers are 
transported or stored. Especially, particulate release may be caused when 
jarring occurs resulting in abrasion between the wafers and the contacted 
surfaces of a wafer cassette. To prevent wafer damage and particulate 
release, the wafers must be held securely within the wafer cassette. 
U.S. Pat. No. 5,452,795 issued to Gallagher et al. relates to an actuated 
rotary retainer for silicone wafer box. The rotary retainer is attached to 
the sidewall of a box to prevent movement of the wafers within a wafer 
cassette during transportation and storage. The rotary retainer consists 
of an elongated shaft, fingers, a coil spring, a first bearing, and a 
second bearing. The first and second bearings are attached to the box, and 
the elongated shaft is rotably coupled to the bores of the first and 
second bearings. The shaft is coupled to the first and second bearings, 
wherein the shaft bottom contacts a door as the box and the door are 
engaged. The shaft rotates through the bore from a first position to a 
second position when the box and the door are engaged. The first and 
second bearings are attached to the box inner sidewall, whereby a peg of 
the shaft first comes into slight contact with the bottom and of a sloped 
rotation member when the box and door are fully engaged. The fingers 
retain the semiconductor wafers within the semiconductor wafer cassette 
when the box is engaged with the door. The wafer retaining fingers are 
positioned on the shaft, whereby, when the box and door are engaged, the 
fingers align with wafers stored in individual slots of the wafer 
cassette. The wafer retaining fingers absorb force from the wafers when 
the box is jarred during transportation. 
Further, U.S. Pat. No. 4,815,912 issued to Maney et al. relates to a box 
door actuated retainer comprising a tongue, a box door member which 
extends along with the length of the tongue, a first parallelogram arm 
attached to the door member, two side arms attached to a box at two 
display locations which form a second parallelogram arm. The first and 
second arms are the same length as are the side arms. The side arms are 
pivotively connected to the first and second arms. When the box door is 
opened and lowered, the box door member is also lowered by the operation 
of gravity, causing the side arms to pivot. The pivoting of the side arms 
causes the tongue to travel not only downward, but also retracting away 
from the wafers contained in a cassette. As such, the cassette and the 
wafers are enabled to be easily withdrawn out of the box. When the 
cassette and the wafers are to be returned back into the box, the box door 
contacts the bottom of the box door member (though until the box door 
contacts the bottom position of the box door member, the retainer remains 
away from the wafers), the tongue moves toward and abutting upon the 
wafers contained in the cassette. Therefore, even if the box may be jarred 
or bumped, the wafers are restrained from any substantial movement. This 
restraint tends to reduce the movement of contamination particles. 
The present invention is intended to provide a wafer retaining mechanism 
having a structure quite different from that disclosed in the '795 patent, 
while somewhat similar to that disclosed in the '912 patent in the sense 
that a linkage is used, the present invention serves to improve the effect 
in retaining the wafers contained in a cassette. 
SUMMARY OF THE INVENTION 
It is thus a primary object of the present invention to provide a wafer 
retaining mechanism being provided with more than one link unit at 
appropriate locations inside and of a box, thereby the link unit retains 
the wafers when the box receives the wafer cassette and contacts a chassis 
attached to the bottom of the wafer cassette. 
It is still an object of the present invention to provide a wafer retaining 
mechanism in which two link units are respectively disposed at two 
neighboring corners inside and of the box, thereby the wafers contained in 
the cassette are retained in a more stable condition. 
It is a further object of the present invention to provide a wafer 
retaining mechanism including an urging plate mounted on an upper link of 
the link unit so as to produce a solid retaining effect against the 
wafers. 
Generally speaking, the wafer retaining mechanism of the present invention 
comprises a box and more than one link unit disposed at appropriate 
locations inside and of the box. The link unit is operative in 
coordination with a wafer cassette, wafers received within the wafer 
cassette, and a chassis attached to the bottom of the wafer cassette, such 
that the link unit may urge the wafers in place when the box receives the 
wafer cassette. The link unit includes a sliding link, a lower link, a 
front link, and an upper link.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Now referring to FIGS. 1 and 2, a wafer retaining mechanism of the present 
invention comprises a box 10 and a plurality of link units 20, wherein the 
box 10 is a hollow body formed with an opening at lower side thereof to 
receive a wafer cassette 30 for storing a plurality of wafers and the 
wafer cassette is affixed with a chassis 40 at the bottom thereof. The 
link units 20 are disposed at appropriate locations inside and of the box 
10. In this embodiment, two link units 20 are respectively disposed at two 
neighboring comers inside and of the box 10. 
As shown in FIGS. 3A to 3C, the link unit 20 includes a sliding link 26, a 
lower link 22, a front link 23, and an upper link 24; wherein the sliding 
link 26 is slidably, telescopically provided on a base link 21 affixed to 
the box 10, the left lower side of the sliding link 26, and the left upper 
side of the base link 21, being respectively provided with tongues 262, 
261 projecting outwards. The tongues 262 and 261 are each formed with 
openings for respectively pivoting the upper link 24 and the lower link 22 
at the right sides thereof, by means of pins 281 and 283. The upper link 
24 and the lower link 22 are pivotally connected with the front link 23 by 
means of pins 282 and 284, wherein the upper link 24 is formed with 
openings 241 and 242 at the pivots and the lower link 22 is formed with 
openings 221 and 222 at the pivots. Alternatively, the upper link 24 can 
be at the right side pivotally connected to the box 10, and the lower link 
22 at the right side to the sliding link 26. Tongues 262 and 261 may be 
provided on the box 10, and on the sliding link 26, for pivotally 
connecting the upper and the lower links 24 and 22. 
In this embodiment, the sliding link 26 is slidably received within the 
base link 21, which is affixed inside the box 10. In practice, the sliding 
rod 26 may be movably disposed inside the box 10 by any measures. In this 
embodiment, the upper end 26a of the sliding link 26 has a smaller 
diameter for receiving a spring 27, which urges against a limit portion 
211 of the base link 21. Therefore, the spring 27 constantly applies 
forces to the sliding rod 26 to urge the sliding link 26 downwards 
subjecting the entire link unit to assume a retracted position. 
When the box 10 covers the wafer cassette 30, the sliding link 26 of the 
link unit 20 undertakes contact with the chassis 40 (as shown in FIG. 3A). 
The sliding link 26 is then forced to move upwards subjecting the lower 
link 22 to move obliquely leftwards and upwards thereby causing the lower 
end of the front link 23 to move obliquely leftwards and upwards (as shown 
in FIG. 3B). When both the sliding link 26 and the lower link 22 urge 
against the chassis 40, the upper end of the front link 23 pivots about 
the upper link 24 to assume a fully expanded position so as to retain the 
wafers securely in the wafer cassette 30. 
Furthermore, the front link 23 may be equipped with a disposable liner 25 
at a front thereof so as to facilitate replacement of contaminated liners 
resulting from multiple contacts with the wafers to constantly maintain an 
uncontaminated contact. The upper link 24 may further be mounted with an 
urging plate 245 undertaking an appropriate angle for pressing against the 
base link 21 when the front link 23 is fully expanded so as to facilitate 
the front link 23 urging against the wafers 50. 
It should be noted that the aforementioned embodiment is not intended to 
limit the scope of the present invention. Various changes and 
implementations with respect to the present invention may be achieved 
without departing the spirit of the present invention. The scope of the 
present invention is defined in the appended claims.