Patent Publication Number: US-2010116623-A1

Title: Transmission device for thin and brittleness substrate

Description:
FIELD OF THE INVENTION 
     The present invention relates to a transmission device for thin and brittleness substrate, and more particularly, to a transmission device structured with greatly improved deformation buffering capability, capable of guiding a thin substrate to move smoothly without causing any damage to the substrate during the transmission, while the same time exerting a sufficient holding force and friction on the substrate for pushing the same to move without causing any damage to the surface of the substrate. 
     BACKGROUND OF THE INVENTION 
     In semiconductor or solar cell industry, substrates such as silicon sheet, silicon plate or wafer, are transported by conventional transmission devices, in which the substrate are pressed and hold by at least a pair of upper pinch roller and lower pinch roller for allowing the substrate to be move on a specific track defined in the transmission device by the fiction exerted from the rotating pinch rollers, and thus sending the substrate to move continuously passing a number of production stations in a manufacturing process, such as chemical soaking station, drying station, and so on. 
     Please refer to  FIG. 1  to  FIG. 4 , which show a conventional transmission device. In the figures, the conventional transmission device  100  comprises: a plurality of transportation rollers  10  and a plurality of pinch rollers  20 . In addition, each transportation roller  10  is further comprised of: a spindle  11 ; two radially extruding supporting wheels  12 , being mounted on the spindle  11  for supporting a substrate  30 ; two track wheels  13 , mounted on the spindle  11  at positions outside the two supporting wheels  12  for defining the substrate  30  to move in a specific track; in which the outer diameter D 13  of each track wheel  13  is larger than the outer diameter D 12  of its corresponding supporting wheel  12 . It is noted that the substrate  30  usually is a brittle device such as a silicon wafer, etc. The plural pinch rollers  20  are arranged above the plural transportation rollers  10  and each of which is composed of: a spindle  21 , arranged parallel with the spindle  11  at a specific distance d away; and a sleeve  22 , having two radially extruding pressing wheels  23  mounted thereon at positions corresponding to the two supporting wheels  12  on the transportation roller&#39;s spindle  11 . As the substrate  30  is sandwiched tightly between the pressing wheels  23  and the supporting wheels  12 , it can be pushed to move by the fiction exerted from the rotating rollers, as shown in  FIG. 4 . Moreover, as the pressing wheels  23  and the supporting wheels  12  are mostly made of rigid materials, the periphery of those wheels  23 ,  12  are covered by buffering tires  231 ,  121  which are usually made of an elastic material such as rubber. In addition, there are two elongated holes  222  formed on the sleeve  22  at two radially opposite positions relative to spindle  21  and each elongated hole  222  is characterized by a specific length L. As shown in  FIG. 2  and  FIG. 4 , the two elongated holes  222  are provided for a pin  24  to pass therethrough for allowing the two ends of the pin  24  to fit loosely therein. Thereby, the pressing wheels  23  of the sleeve  22  can press naturally on their corresponding supporting wheels  12 , and the same time that the sleeve  22  is prevented from moving axially by the restriction of the pin  24  but only allows to rotate about the axis thereof as the angular range of rotation of the sleeve  22  is defined by the specific length L of the two elongated holes  222 . 
     As shown in  FIG. 3  and  FIG. 4 , when the spindle  11  is driven to rotate by an external power source, the supporting wheels  12  and the track wheels  13  will be brought to rotate as well. Thus, the elastic buffering tires  121  will exert a friction on the substrate  30  which is placed on the supporting wheels  12  for pushing the substrate  30  to move forward along with the rotate of the supporting wheels  12 . When the substrate  30  approaches the pressing wheels  20 , the pushing from the forward moving substrate  30  will lift the pressing wheels  23  and the sleeve  22  for allowing the substrate  30  to be tightly sandwiched between the pressing wheels  23  and the baring wheels  12  by the elasticity and friction of the buffering tires  121 ,  231 . Thereby, the substrate  30  can be prevented from skewing by vibration as it is being driven to move, which is especially true for preventing the substrate from sliding and the consequent crush when the substrate  30  is moving on an inclined track for transporting the same to or away from a chemical soaking pool. 
     However, the aforesaid substrate transmission is short in that: despite that the periphery of those wheels  23 ,  12  are covered by buffering tires  231 ,  121 , the process of transmitting the substrate  30  continuously might not be carried out smoothly as the volumes of the elastic buffering tires  231 ,  121  are comparatively smaller in relative to those of the rigid wheels  23 ,  12  so that the buffering tires  231 ,  121  may not be sufficiently deformed for smoothing the substrate transmission. The above description is especially true when the track of the substrate is inclined. For instance, when a substrate, being brought to move on an inclined track, encounters a pressing wheel  12  while the pushing of moving substrate is unable to raise the pressing wheel  12 , the rigidity of the corresponding supporting wheel  23  with insufficiently deformed buffering tire  231  will hamper the substrate transmission in a way that the sequentially transmitted substrates may collide with one another and thus cause damage to the substrates by overly high clipping force, or by compressing and buckling resulting from the collision. 
     Therefore, the material selection as well as the resulting deformation design for the supporting wheels  12 , the pressing wheels  23 , and the buffering tires  121 ,  231  are becoming key issues for configuring a transmission device capable of exerting a sufficient holding force and friction on the substrate  30  for pushing the same to move without causing any damage to the surface of the substrate, and the same time capable of providing more sufficient deformation for guiding the thin substrate  30  to move smoothly without causing the sequentially transmitted substrates to collide with one another and thus causing the same to be damaged by overly high clipping force, or by compressing and buckling resulting from the collision. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a transmission device for thin and brittleness substrate that is a transmission device structured with greatly improved deformation buffering capability, capable of guiding a thin substrate to move smoothly without causing any damage to the substrate during the transmission, while the same time exerting a sufficient holding force and friction on the substrate for pushing the same to move without causing any damage to the surface of the substrate. 
     To achieve the above object, the present invention provides a transmission device for thin and brittleness substrate, primarily comprising a plurality of transportation rollers and a plurality of pinch rollers, in which each transportation roller further comprises: a spindle, made of a rigid material; and a plurality of supporting wheels, made of an elastic material such as rubber and being radially disposed on the spindle while protruding out therefrom; and each pinch roller comprises: a sleeve; a spindle, being ensheathed in the sleeve; and a plurality of pressing wheels, made of an elastic material such as rubber and being radially disposed on the sleeve while protruding out therefrom at positions corresponding to the supporting wheels mounted on the spindle of the transportation roller. 
     Further scope of applicability of the present application will become more apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention and wherein: 
         FIG. 1  is a schematic diagram showing a conventional transmission device. 
         FIG. 2  is a top view of a pinch roller used in the conventional transmission device of  FIG. 1 . 
         FIG. 3  is a cross sectional view of the conventional transmission device of  FIG. 1 . 
         FIG. 4  is a side view of the conventional transmission device of  FIG. 1 . 
         FIG. 5  is a cross sectional view of a transmission device according to a first embodiment of the invention. 
         FIG. 6  shows stress-deformation curves for the transmission device of  FIG. 5  and the conventional transmission device of  FIG. 1 . 
         FIG. 7  is a cross sectional view of a transmission device according to a second embodiment of the invention. 
         FIG. 8  is a cross sectional view of a transmission device according to a third embodiment of the invention. 
     
    
    
     DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
     For your esteemed members of reviewing committee to further understand and recognize the fulfilled functions and structural characteristics of the invention, several exemplary embodiments cooperating with detailed description are presented as the follows. 
     Please refer to  FIG. 5 , which is a cross sectional view of a transmission device according to a first embodiment of the invention. The transmission device  200  of  FIG. 5  includes a plurality of transportation rollers  40  and a plurality of pinch rollers  50 . Each transportation roller  40  is further comprised of: a rigid spindle  41 ; a rubber layer  411 , being formed wrapping on the exterior of the spindle  41  for covering the same; two radially extruding supporting wheels  42 , being formed on the rubber layer  411  while mounting on the spindle  11  for supporting a substrate  30 ; and two track wheels  43 , mounted on the spindle  41  at positions outside the two supporting wheels  12  for defining the substrate  30  to move in a specific track; in which the outer diameter D 43  of each track wheel  43  is larger than the outer diameter D 42  of its corresponding supporting wheel  42 . It is noted that the substrate  30  usually is a brittle device such as a solar wafer, etc. Moreover, the plural pinch rollers  50  are arranged above the plural transportation rollers  40  and each of which is composed of: a spindle  51 , arranged parallel with the spindle  41  at a specific distance d away; and a sleeve  52 , having two radially extruding pressing wheels  53  mounted thereon at positions corresponding to the two supporting wheels  42  on the transportation roller&#39;s spindle  41 . In this embodiment, there is an elastic buffering tire  531  disposed on the periphery of each pressing wheel  531  as the buffering tire  531  can be made of rubber. Moreover, there are two elongated holes  522  formed on the sleeve  52  at two radially opposite positions relative to spindle  51  and each elongated hole  522  is characterized by a specific length L, similar to those shown in  FIG. 2  and FIG.  4  As shown in  FIG. 5 , the two elongated holes  522  are provided for a pin  54  to pass therethrough for allowing the two ends of the pin  54  to fit loosely therein. Thereby, the pressing wheels  53  of the sleeve  52  can press naturally on their corresponding supporting wheels  42 , and the same time that the sleeve  52  is prevented from moving axially by the restriction of the pin  54  but only allows to move up and down along the pin  54 . As the substrate  30  is sandwiched tightly between the pressing wheels  53  and the supporting wheels  52 , it can be pushed to move by the fiction exerted from the rotating rollers while being tightly confined in between, as shown in  FIG. 5 . 
     The transmission device of the invention is characterized in that: its supporting wheels  42  are made of a rubber, such as NBR, HNBR, FPM, Silicone, PTFE, TFM, CR or AR, etc. In this embodiment, the supporting wheels  42  are integrally formed with the rubber layer  411 , and similarly the pressing wheels  53  are also integrally formed with the sleeve  52 . As for the type of rubber selected for making rubber layer  411 , it is dependent upon the sizes of the supporting wheels  42  and the pressing wheel  53  and also upon the material of the substrate that is being transmitted thereby and its size as well, so that there is no special restriction regarding to material of the rubber layer  411 . Moreover, the supporting wheels  42  and the pressing wheel  53  can either be made of the same or different materials, but they should all be made of a material with acid and alkali resistance so that they can be adapted for the substrate transmission operation in a manufacturing process with chemical soaking or etching procedures. In this embodiment, when the supporting wheels  42  are entirely made of rubber, their deformation, that is resulted from the pushing of the substrate  30  moving up on down by an inclined angle to be sandwiched between the supporting wheels  42  and the pressing wheels  53 , is about three times of that comparing with the conventional supporting wheels that are made of a rigid material. Thus, by the cooperation between the sufficient deformation of the supporting wheels  42  and the up-and-down mobility of the pressing wheels  53 , the substrate  30  can be move smoothly and thus preventing the same from being damaged by overly high clipping force, or by compressing and buckling resulting from the collision in the transmission. 
     Please refer to  FIG. 6 , which shows stress-deformation curves for the transmission device of  FIG. 5  and the conventional transmission device of  FIG. 1 . In the experiment described in  FIG. 6 , three kinds of baring wheels that are made of different materials are used for simulating how they are deformed by stress from a substrate carried thereby. In  FIG. 6 , the curve L 1  represents the deformation of a conventional rigid supporting wheel  12  that is warped with a buffering tire  121  as the one shown in  FIG. 3 ; and the curve L 2  represents the deformation of the supporting wheel  42  shown in  FIG. 5 , which is made of rubber. From the curve L 1  it is noted that when the deformation of the supporting wheel  12  increases from 1.0×10 −4  m to 1.7×10 −3  m, the stress for causing such deformation will increase from 6,500 kg/m 3  to 200,000 kg/m 3  that such stress will also act on the substrate and thus cause the same to break. On the other hand, from the curve L 2  it is noted that when the deformation of the supporting wheel  42  increases from 1.0×10 −4  m to 1.7×10 −3  m, the stress for causing such deformation will increase from 3,600 kg/m 3  to 25,000 kg/m 3  by that the stress acting on the substrate is greatly reduced and thus the substrate is less likely t be damaged. As for the curve L 3  in  FIG. 6 , it is resulting from a rigid supporting wheel  12  with buffering tire  121  similar to the conventional supporting wheel  12  shown in  FIG. 3 , but is different in that the diameter of the buffering tire  121  used in the supporting wheel of L 3  is about twice that of the one used in L 1 . For instance, the thickness of the buffering tire resulting the curve L 1  is 5 mm and the thickness of the buffering tire resulting the curve L 3  is 10 mm. Thus, in curve L 3 , when the deformation of the supporting wheel  12  increases from 1.0×10 −4  m to 1.7×10 −3  m, the stress for causing such deformation will increase from 5,500 kg/m 3  to 75,000 kg/m 3 , indicating that despite the increasing of thickness in buffering tire  121 , the stress acting on the substrate is still larger than that acting on the substrate carried by the supporting wheels of the present invention. Accordingly, the rubber supporting wheel  42  of the invention is the best for preventing the substrate from damaging by stress. However, by the use of thicker buffering tire, the conventional rigid baring wheel can perform better than those with thinner buffering wheel. 
     Please refer to  FIG. 7 , which is a cross sectional view of a transmission device according to a second embodiment of the invention. In  FIG. 7 , only a pair of transportation roller  40 A and its corresponding pinch roller  50  are shown, in which the pinch roller  50  includes a spindle  51 , a sleeve  52 , a pressing wheel  53  and a buffering tire  531 ; and the transportation roller  40 A includes: a rigid spindle  41 A; a rubber layer  411 A formed on the spindle  41 A for covering the same; and a radially extruding rubber supporting wheel  42 A, integrally formed with the rubber layer  411 A. The present embodiment is characterized in that: there is further a rubber buffering tire  421 A formed on the periphery of the rubber supporting wheel  42 A. Accordingly, in this embodiment, all the supporting wheel  42 A, the pressing wheel  53  along with their buffering tire  421 A,  531  are all made of a rubber, and the rubber can be NBR, HNBR, FPM, Silicone, PTFE, TFM, CR or AR. Similarly, the supporting wheel  42 A, the pressing wheel  53  along with their buffering tire  421 A,  531  can either be made of the same or different materials, but they should all be made of a rubber with acid and alkali resistance so that they can be adapted for the substrate transmission operation in a manufacturing process with chemical soaking or etching procedures. 
     Please refer to  FIG. 8 , which is a cross sectional view of a transmission device according to a third embodiment of the invention. Similar to that shown in  FIG. 7 , the present embodiment also only shows a pair of transportation roller  40 B and its corresponding pinch roller  50 , in which the pinch roller  50  includes a spindle  51 , a sleeve  52 , a pressing wheel  53  and a buffering tire  531 ; and the transportation roller  40 B includes: a spindle  41 B, a rubber layer  411 B, a supporting wheel  42 B and a buffering tire  421 B. The present embodiment is characterized in that: there is further a plastic buffer layer  422 B sandwiched between the buffering tire  421 B and the periphery of the supporting wheel  42 B. For instance, the second buffer layer  422 B can be made of PVC. Similarly, all the supporting wheel  42 B, the pressing wheel  53  along with their buffering tire  421 B,  531  are all made of a rubber, and the rubber can be NBR, HNBR, FPM, Silicone, PTFE, TFM, CR or AR. Moreover, the supporting wheel  42 A, the pressing wheel  53  along with their buffering tire  421 A,  531  can either be made of the same or different materials. 
     To sum up, the present invention relates to a transmission device for thin and brittleness substrate with greatly improved deformation buffering capability, capable of guiding a thin substrate to move smoothly without causing any damage to the substrate during the transmission, which is especially true even when the transmission track of the substrate is inclined and the pushing of moving substrate is unable to raise the pressing wheel, the deformation of the supporting wheel  42  is large enough for guiding the substrate to be correctly sandwiched between the supporting wheel and the pressing wheel  53  for preventing the substrate from being damaged by overly high clipping force, or by compressing and buckling resulting from the collision, while the same time exerting a sufficient holding force and friction on the substrate for pushing the same to move without causing any damage to the surface of the substrate. 
     With respect to the above description then, it is to be realized that the optimum dimensional relationships for the parts of the invention, to include variations in size, materials, shape, form, function and manner of operation, assembly and use, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present invention.