Patent Publication Number: US-2015076273-A1

Title: Spooling process films

Description:
BACKGROUND 
     Process films (including substrates) find many applications in high-technology device manufacture. A process film typically has an active surface and a passive surface. The passive surface can be handled and manipulated with ease, but functional devices, layered coatings, and components may be formed or placed on the active surface, and as a result the active surface may easily be contaminated or damaged by any physical contact during processing. For this reason, various kinds of cassettes and track systems have been developed tier handling process films in ways that do not risk contaminating their active surfaces. In the semiconductor industry, the front-opening unified pod (FOUP) style of standardized wafer cassette handing is widely used to hold silicon wafers; a wafer can be removed from such a pod for processing or measurement as needed by special tools. Similar processes are used for handling thin-film transistor (TFT) glass substrates. In the plastic patterning industry disposable interleaves are sometimes used for handling such process films as touch-screen and membrane switch constituents. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The figures are not drawn to scale. They illustrate the disclosure by examples. 
         FIG. 1A  is a perspective view of an example of spooling apparatus. 
         FIG. 1B  is a perspective view of another example of spooling apparatus. 
         FIG. 1C  is a perspective view of another example of spooling apparatus. 
         FIG. 2A  is a sectional view of an interposer film and a process film rolled up around a core with the process film adjacent a back surface of the interposer film according to an example. 
         FIG. 2B  is a sectional view of an interposer film and a process film rolled up around a core with the process film adjacent a spacer surface of the interposer film according to an example. 
         FIG. 3  is a sectional view of an interposer film and a process film rolled up around a core according to another example. 
         FIG. 4  is a perspective view of an example of an interposer film with spacers formed as parallelepipeds. 
         FIG. 5  is a perspective view of an example of an interposer film with frusto-conical spacers. 
         FIG. 6  is a perspective view of an example of a gas-permeable interposer film with gas-permeable spacers formed as continuous strips. 
         FIG. 7  is a perspective view of an example of an interposer film formed as a mesh. 
         FIG. 8  is a perspective view of an example of an interposer film having a textured surface. 
         FIG. 9  is a perspective, partially cut away, of layers of process film separated by layers of interposer film. 
         FIG. 10  is a perspective of two strips of process film side-by-side between each layer of interposer film according to an example. 
         FIG. 11A  is a perspective view of an example of an interposer film carrying a plurality of supports on a spacer surface. 
         FIG. 11B  is similar to  FIG. 11A  and with a process film on the supports. 
         FIG. 12A  is a perspective view of an example of an interposer film carrying a plurality of supports on a back surface. 
         FIG. 12B  is similar to  FIG. 12A  and with a process film on the supports. 
         FIG. 13A  is a front-side schematic of an example of passive-surface process film spooling apparatus showing process film beginning to move from a full spool toward an empty spool. 
         FIG. 13B  is a back-side schematic of the spooling apparatus shown in  FIG. 13A . 
         FIG. 14  is a flowchart illustrating a method of processing process films according to an example. 
         FIG. 15  is a flowchart illustrating a method of processing process films according to another example. 
         FIG. 16  is a flowchart illustrating a method of processing process films according to another example. 
     
    
    
     DETAILED DESCRIPTION 
     Illustrative examples and details are used in the drawings and in this description, but other configurations may exist and may suggest themselves. Parameters such as voltages, temperatures, dimensions, and component values are approximate. Terms of orientation such as up, down, top, and bottom are used only for convenience to indicate spatial relationships of components with respect to each other, and except as otherwise indicated, orientation with respect to external axes is not critical. For clarity, some known methods and structures have not been described in detail. Methods defined by the claims may comprise steps in addition to those listed, and except as indicated in the claims themselves the steps may be performed in another order than that given. Accordingly, the only limitations are imposed by the claims, not by the drawings or this description. 
     Roll-to-roll fabrication of active surfaces on process films has been difficult. In complex processes there often are only limited stages in which a film can be rolled up. This is because rolling up the film results in the active side in one wrap of the roll contacting the passive side in a succeeding wrap. In a process involving coating the active surface with a sensitive or adhesive material such as photoresist or barrier coating, the process must continue in-line through cure and bake steps before the film can be rolled up. In addition, even in fabrication stages where rolling up is possible, contamination and mechanical damage introduced by rolling and re-roiling can damage the active surface or components on it. Even in processes where interleaves are used there is a risk of contamination. Moreover, interleaves can introduce static electric charges that not only can damage components on the active surface but also can attract dust and other forms of small particulate contamination. There has been a need for a way to roll up a process film at various fabrication stages without inflicting damage. 
     As shown in  FIG. 1A , an example of spooling apparatus includes an interposer film generally  100  having a spacer surface  102  and a back surface  104 . A first spacer  106  is carried by the interposer film  100  on its spacer surface  102  adjacent first edge  108  of the interposer film. A second spacer  110  is carried by the interposer film  100  on the spacer surface  102  adjacent a second edge  112  of the interposer film  100 . A process-film protective space  114  is defined between the first and second spacers. A rotatable core  116  is oriented to roll up the interposer film as indicated by an arrow  118  together with a process film (not shown) in the process-film protective space  114  with a passive surface of the process film adjacent a surface of the interposer film. In this example the interposer film  100  wraps around the core  116  with the spacer surface  102  facing the core, as indicated by an arrow  120  showing the core rotating about its axis  122  in an anticlockwise direction when viewed from a near end  124  of the core  116 . The protective space  114 , defined between the spacers  106  and  110 , extends from the spacer surface  102  to a back surface of an adjacent layer (or wrap) of the interposer film when the film is rolled up. 
     As shown in  FIG. 1B , in some examples the interposer film  100  wraps around the core  116  with the back surface  104  facing the core as indicated by an arrow  126 . 
     In the example of  FIG. 1A  the core is shown in the form of a solid shaft, but the core may take other forms.  FIG. 1C  gives an example of spooling apparatus that is similar to that shown in  FIG. 1A  except that a first flanged wheel  128  adjacent the first edge  108  of the interposer film  100  and a second flanged wheel  130  adjacent the second edge  112  of the interposer film  100  are used as a core rather than a solid shaft. 
     Referring now to  FIG. 2A , a length of interposer film  200  with spacers on either edge is shown rolled up around a core  202 . A first portion  204  of the interposer film  200  is closest to the core  202  and carries a first portion  206  of a spacer along one edge and a first portion  208  of a spacer along an opposite edge. The term “portion” refers to one layer (or wrap) of film or spacer extending all the way around the core. A first portion (layer or wrap) is adjacent the core and successive layers or wraps are wound one on top of the previous one as the film and spacers are wound up. The first portions  206  and  208  of the spacers are adjacent to, and in some examples rest on, the core  202 . 
     A second portion  212  of the interposer film  200  carries second portions  214  and  216  of spacers that rest on the first portion  204  of the interposer film. A third portion  218  of the interposer film  200  carries third portions  220  and  222  of spacers that rest on the second portion  212  of the interposer film. 
     A length of process film  224  is also rolled up around the core. A first portion  226  of the process film  224  is located in a portion  228  of protective space formed between the spacers. As with the interposer film, the first portion  226  of the process film may be considered as a first layer (first wrap) around the core. A first portion  230  of an active surface of the process film  224  carries various items such as features, coatings, functionalisations, patterns, or components  232 A,  232 B,  232 C, and  232 D. These items are installed on, formed in, or otherwise placed on the active surface of the process film. A first portion  234  of a passive surface of the process film  224  is adjacent a first portion  236  of a back surface of the interposer film  200 . The first portion  234  of the passive surface of the process film  224  is supported by the first portion  236  of the back surface of the interposer film  200 . As will be discussed in more detail presently, the process film is tensioned sufficiently to maintain contact between it and the back surface of the interposer film. 
     The first portion  228  of the protective space extends between the first portion  236  of the back surface of the interposer film and a second portion  238  of the spacer surface of the interposer film. The spacers are sized such that the protective space fully contains the process film without any contact between the spacer surface of the interposer film and the active surface of the process film. 
     A second portion  240  of the process film  224  is located in a second portion  242  of the protective space between the spacers. A second portion  24 . 4  of the passive surface of the process film is adjacent a second portion  246  of the back surface of the interposer film. 
     A spool thus formed may comprise fewer or more, in some examples many more, wraps than the three wraps of interposer film and two wraps of process film shown in  FIG. 2A . 
       FIG. 2B  is generally similar to  FIG. 2A  except that a process film is shown interleaved with an interposer film around a core with a passive surface of the process film adjacent a spacer surface of the interposer film. More particularly, a length of interposer film  248  with spacers on either edge is shown rolled up around a core  250 . A first portion  252  of the interposer film is closest to the core and carries a first portion  254  of a spacer along one edge and a first portion  256  of a spacer along an opposite edge. A second portion  258  of the interposer film carries second portions  260  and  262  of spacers that rest on the first portion  252  of the interposer film. A third portion  264  of the interposer film carries third portions  266  and  268  of spacers that rest on the second portion  258  of the interposer film. 
     A length of process film  270  is also rolled up around the core. A first portion  272  of the process film  270  is located in a portion  274  of protective space formed between the spacers. A first portion  276  of an active surface of the process film carries various items such as features, coatings, functionalisations, patterns, or components  278 A,  278 B,  278 C, and  278 D. These items are installed on, formed in, or otherwise placed on the active surface of the process film. A first portion  280  of a passive surface of the process film lies adjacent a first portion  282  of a spacer surface of the interposer film. The first portion  280  of the passive surface of the process film is supported by the first portion  282  of the back surface of the interposer film. 
     A second portion  284  of the process film is located in a second portion  286  of the protective space between the spacers. A second portion  288  of the passive surface of the process film is adjacent a second portion  290  of the spacer surface of the interposer film. Similarly, a third portion  292  of the process film is located in a third portion  294  of the protective space between the spacers with a third portion  296  of the passive surface of the process film adjacent a third portion  298  of the spacer surface of the interposer film. 
       FIG. 3  is generally similar to  FIG. 2A  except that in this example an interposer film  300  is wound up around a core  302  with a first portion  304  of a back surface of the interposer film adjacent to, and in some examples supported by, the core  302 . A first portion (or wrap, or layer)  306  of the interposer film  300  carries a first portion  308  of a first spacer and a first portion  310  of a second spacer. A second portion  312  of the interposer film lies on the first portions  308  and  310  of the spacers and in turn carries second portions  314  and  316  of the spacers. A third portion  318  of the interposer film lies on the second portions  314  and  316  of the spacers and in turn carries third portions  320  and  322  of the spacers. 
     A length of process film  324  is also rolled up around the core  302 . A first portion  326  of the process film  324  is located in a first portion  328  of a protective space formed between the spacers. Various features, coatings, functionatisations, patterns or components  330 A,  330 B,  330 C, and  330 D are installed or formed on a first portion  332  of an active surface of the process film. A first portion  334  of a passive surface of the process film is adjacent a first portion  336  of a spacer surface of the interposer film. The first portion  328  of the protective space is bounded by the first portion  336  of the spacer surface and a second portion  338  of the back surface of the interposer film. The process film is tensioned sufficiently to hold its passive surface against the spacer surface of the interposer film such that the active surface of the process film does not contact the back surface of the interposer film. 
     A second portion  340  of the process film  324  is located in a portion  342  of the protective space between the spacers. A second portion  344  of the passive surface of the process film lies on a second portion  346  of the spacer surface of the interposer film. Similarly, a third portion  348  of the process film  324  is located in a third portion  350  of the protective space. A third portion  352  of the passive surface of the process film lies on a third portion  354  of the spacer surface of the interposer film. As with the other portions of the protective space, the third portion  350  of the protective space lies between the back and spacer surfaces of the interposer film; in this instance, the third portion  350  of the protective space lies between the third portion  354  of the spacer surface of the interposer film and a portion of the back surface of a fourth portion (not shown) of the interposer film. 
     Returning to the example of  FIG. 1A , the first spacer  106  is shown as a segmented strip. The second spacer  110  is also shown as a segmented strip. The interposer film and the spacers are made of materials that are sufficiently compliant to roll up around the core  116 . In this example the spacers  106  and  110  are adjacent to, and in some examples are in contact with, the core as the rolling up begins. The elements in this and the other figures are not drawn to scale, and the core may actually be larger or smaller relative to the spacers than as depicted in the drawings. 
       FIG. 4  shows an example of an interposer film  400 , a plurality of individual spacer elements  402  located at intervals along a first edge  404  of the interposer, and a plurality of individual spacer elements  406  located at intervals along a second edge  408  of the interposer. in this example the spacer elements are shaped as parallelepipeds, but the shape is not critical and spacer elements having other shapes may be used. For example,  FIG. 5  shows an interposer  500  with frusto-conical spacers  502 . 
     The example of  FIG. 4  also includes a transverse stiffener  410  embedded in the interposer  400 . This stiffener extends from the first edge  404  to the second edge  408 , but in other examples the stiffener may not extend this far. A plurality of similar stiffeners may be disposed at intervals along the interposer. The stiffener  410  is shown at right angles to the edges, and therefore it does not interfere with rolling on the interposer onto a core. In other examples the stiffeners may be disposed across the interposer at other angles so long as the stiffeners do not interfere with rolling up the interposer. The interposer may also be formed of a material with anisotropic compliance, retaining transverse stiffness whilst capable of forming a longitudinal roll. 
       FIG. 6  is an example of an interposer film  600  with first and second spacers  602  and  604  each formed as a continuous strip of material. The spacer material must be sufficiently compliant as to permit rolling up onto a core. In this example the interposer film and the spacers have been made gas-permeable by a plurality of openings such as openings  606  in the interposer film, openings  608  in the first spacer, and openings  610  in the second spacer. Making one or more of the interposer film and the spacers gas-permeable facilitates escape of gases that may be emitted by a process film adjacent the interposer film  600  and ingress and flow of reactive gaseous materials to allow in-spool process changes to the process film. The openings may be formed by any convenient method. In other examples the interposer film and spacer materials may lack special openings but may be sufficiently porous as to be gas permeable. 
       FIG. 7  gives an example of an interposer film  700  formed of mesh material. As with the example of  FIG. 6 , the mesh facilitates movement of gases. In this example the interposer  700  carries first and second spacers  702  and  704  formed as segmented strips, and in other examples a mesh interposer film may carry any other suitable spacers. 
       FIG. 8  is an example of an interposer film  800  having a textured spacer surface  802 . The texturing may be in any suitable pattern to avoid or mitigate stiction between the textured surface and a process film that may contact the surface, or to facilitate access of gases or reactive gaseous materials to the process film. In other examples aback surface  804  of the interposer film  800  may be textured. In this example the interposer film  800  carries first and second spacers  806  and  808  formed as segmented strips, but the spacers may take other forms, for example as described above. 
       FIG. 9  shows wraps of process film separated from each other by wraps of interposer film. A first portion (layer or wrap)  900  of an interposer film carries first spacers  902  and second spacers  904 . A second portion  906  of the interposer film carries first spacers  908  and second spacers  910  defining therebetween a protective space  912 . A third portion  914  of the interposer film carries first spacers  916  and second spacers  918  defining therebetween a protective space  920 . A passive surface  922  of a first portion  924  of a process film is disposed adjacent a back surface  926  of the first portion  900  of the interposer film. An active surface  928  of the first portion  924  of the process film carries components, layers or features  930 A and  930 B. The active surface  928  resides in the protective space  912  and makes no contact with any other portion of the process film or any portion of the interposer film. A passive surface  932  of a second portion  934  of the process film is disposed adjacent a back surface  936  of the second portion  906  of the interposer film. An active surface  938  of the second portion  934  of the process film resides in the protective space  920  and makes no contact with any other portion of the process film or any portion of the interposer. The active surface  938  may carry components, layers or features (not shown). A passive surface  940  of a third portion  942  of the process film is disposed adjacent a back surface  944  of the third portion  914  of the interposer film. 
     More than one process film strip may be disposed adjacent a single interposer film. As shown in  FIG. 10 , a first portion  1000  of an interposer film carries a spacer  1002  adjacent a first edge of its spacer surface  1004 , a spacer  1006  adjacent a second edge, and a spacer  1008  in the middle. A second portion  1010  of the interposer film, disposed beneath a back surface  1012  of the first portion  1000  of the interposer film, carries a spacer  1014  adjacent a first edge of its spacer surface  1016 , a spacer  1018  adjacent a second edge, and a spacer  1020  in the middle. 
     A first portion  1022  of a first process film  102 . 4  is disposed in a protective space between the spacers  1014  and  1020 . A second portion  1026  of the first process film  1024  is disposed in a protective space between spacers (not shown) carried by a third portion (not shown) of the interposer film. A passive surface  1028  of the first portion  1022  of the first process film  1024  is adjacent the back surface  1012  of the first portion  1000  of the interposer film. A passive surface  1030  of the second portion  1026  of the first process film  1024  is adjacent a back surface  1032  of the second portion  1010  of the interposer film. 
     A first portion  1034  of a second process film  1036  is disposed in a protective space between the spacers  1018  and  1020 . A second portion  1038  of the second process film  1036  is disposed in a protective space between spacers (not shown) carried by the third portion (not shown) of the interposer film. A passive surface  1040  of the first portion  1034  of the second process film  1036  is adjacent the back surface  1012  of the first portion  1000  of the interposer film. A passive surface  1042  of the second portion  1038  of the second process film  1036  is adjacent the back surface  1032  of the second portion  1010  of the interposer film. 
     An active surface  1044  of the first portion  1022  of the first process film  1024  may carry components, layers or features (not shown) and is not touched by the interposer film or by any other portions of process film. Similarly, an active surface  1046  of the second portion  1026  of the first process film  1024 , an active surface  1048  of the first portion  1034  of the second process film  1036 , and an active surface  1050  of the second portion  1038  of the second process film  1036 , are untouched by the interposer film or any other portions of process film. For example a component  1052  is disposed on the active surface  1046 , a component  1054  is disposed on the active surface  1048 , and a component  1056  is disposed on the active surface  1050 . 
     As shown in  FIG. 11A , a plurality of supports  1100 ,  1102 ,  1104 , and  1106  may be carried by an interposer film  1108 . The supports are carried on a spacer surface  1110  of the interposer film  1108 , as are spacers  1112  along one edge of the interposer  1108  and spacers  1114  along another edge of the interposer  1108 .  FIG. 11B  is similar to  FIG. 11A  except that a process film  1116  is shown in a protective space between the spacers  1112  and  1114 . An active surface  1118  of the process film  1116  is in contact with the supports and has a component  1120 . The support  1100  contacts the active surface  1118  of the process film  1116  only along a first edge  1122  where it will not do any damage to components or other active elements in any active region of the process film. Similarly the support  1102  contacts the active surface  1118  only along a second edge  1124 , remote from any active region of the process film. 
     In  FIGS. 11A and 11B , the supports are carried on the spacer surface of the interposer. As shown in  FIGS. 12A and 12B , supports  1200  and  1202  may be carried on a back surface  1204  of an interposer film  1206 . Spacers  1208  are carried along one edge of a spacer surface  1210  of the interposer  1206  and spacers  1212  along another edge of the interposer  1206 . A portion  1214  of a process film  1216  is supported by the supports  1200  and  1202  in a protective space between spacers (not shown) of another portion (not shown) of the interposer film. As in the example of  FIGS. 11A and 11B , an active surface  1218  of the process film  1216  is supported by the supports  1200  and  1202  along edges that are remote from any components such as a component  1220  or any active region of the active surface  1218  of the process film  1216 . 
     In the foregoing two examples, the supports comprise spaced-apart parallelepipeds, but in other examples the supports may take the for of segmented strips, continuous strips, or other suitable shapes as desired. 
     An example of passive-surface process film spooling apparatus generally  1300  is shown in  FIGS. 13A and 13B . A first cassette  1302  contains a spool  1304  of a process film  1306  wound up in layers on a core  1308 . On the spool  1304 , each layer of the process film  1306  occupies a protected space formed by one or more layers of a first interposer film  1310  in a manner as described above. The process film  1306  unwinds from the spool  1304 , exits the first cassette  1302  through an opening  1312 , and passes through a process station  1314 . Any suitable process may be carried out on the process film  1306  in the process station  1314 . From the process station  1314 , the process film  1306  enters a second cassette  1316  through an opening  1318 . The process film  1306  is interleaved with a second interposer film  1320  and both films are wound up on a core  1322  to forma spool  1324  with the process film  1306  occupying protective spaces formed by layers of the second interposer film  1320  in a manner as described above. Eventually all of the process film  1306  has been transferred from the first cassette  1302  to the second cassette  1316 . Then the second cassette  1316  can be removed from the apparatus  1300  and used to safely store or transport the process film  1306 . 
     The process film  1306  may be guided from the first cassette  1302  through the process station  1314  to the second cassette  1316 , for example by a first tension roller  1326  between the first cassette  1302  and the process station  1314  and a second tension roller  1328  between the process station  1314  and the second cassette  1316 . The first and second tension rollers contact the process film  1306  only on a passive side  1330 . Other guides may also be used, such as a draw roller  1332  and a nip wheel  1334  between the tension roller  1326  and the process station  1314 , and a draw roller  1336  and a nip wheel  1338  between the process station  1314  and the tension roller  1328 . 
     As the process film unwinds from the spool  1304 , the first interposer film  1310  also unwinds and exits the first cassette through the opening  1312 . The first interposer film may be wound up to form a spool  1340  on a core  1342 . The first interposer film may pass over one or more guides such as a tension roller  1344  as it is unwound from the spool  1304  in the first cassette  1302  and is wound onto the spool  1340 . When the process film  1306  and the first interposer film  1310  have been unwound from the spool  1304  and the first interposer film  1310  has been wound onto the spool  1340 , the spool  1340  of interposer film may be removed from the apparatus  1300  and reused later, left in situ, or wound back into the cassette without process film for storage. 
     The second interposer film  1320  may be obtained by unwinding from a spool  1346  on a core  1348 . The second interposer film  1320  may pass over one or more guides such as a tension roller  1350  and enters the second cassette  1316  through the opening  1318 . 
     In some examples the opening  1312  may be sealed with a cover  1352  except when the films are being unwound from the spool  1304 . Similarly, the opening  1318  may be sealed with a cover  1354  except when the films are being wound up on the spool  1324 . 
     As the process film is wound onto the spool  1324 , it may be tensioned by a servo motor  1356  that drives the core  1322 . In some examples the process film is also tensioned by one or more of the tension roller  1328 , the tension roller  1326 , or any other components. In some examples a servo motor (not shown) may be mechanically coupled to the core  1308  and may be used to tension the process film as it is unwound. In some examples a friction brake  1358  applied to a drum  1360  coupled to the core  1308  may be used to tension the process film as it is unwound. Instead of the servo motor  1356 , some other kind of motor or a hand crank may be used to provide torque to wind the process and interposer films onto the core  1322 . 
     A servo motor  1362  or other suitable motive device may be used to wind the first interposer film  1310  onto the core  1342  as the process film  1306  and the first interposer film  1310  unwind from the spool  1304 . Another servo motor (not shown) or a friction brake  1364  applied to a drum  1366  carried by or coupled to the core  1348  may be used to tension the second interposer film  1320  as it unwinds from the spool  1346 . 
       FIG. 14  gives an example of a method of processing process films. The method. includes providing an interposer film having a spacer surface and a back surface, the spacer surface having a first spacer adjacent a first edge of the interposer film and a second spacer adjacent a second edge of the interposer film, and at least one protective space defined between the first and second spacers ( 1400 ); and winding a process film and the interposer film onto a core with the process film disposed in the protective space between the first and second spacers and a passive surface of the process film adjacent a surface of the interposer film ( 1402 ). 
       FIG. 15  gives another example of a method of processing process films. As in the previous example, a first interposer film having a spacer surface and a back surface is provided, the spacer surface having a first spacer adjacent a first edge of the interposer film and a second spacer adjacent a second edge of the interposer film with least one protective space defined between the first and second spacers ( 1500 ). The first interposer film is tensioned ( 1502 ). In some examples a process film is tensioned at less tension than the first interposer film ( 1504 ). The films are wound onto a core with the process film disposed in the protective space between the first and second spacers and with a passive surface of the process film adjacent a surface of the interposer film ( 1506 ). Tension in the interposer film, not tension in the process film, forms the spool. 
     In some examples a process is carried out on the process film as the film is being wound up ( 1508 ). This procedure has been discussed previously in connection with  FIGS. 13A and 13B , where the process film is fed through a process station and then wound up. 
     In other examples the process is carried out after the films have been wound up ( 1510 ). As one example, the spooled-up film may be placed into a process station and the process performed on the entire spool at once. An interposer film that is porous or perforated as described previously may be used in this instance. 
       FIG. 16  gives another example of a method of processing process films. An unprocessed process film spooled with a first interposer film is provided with a passive surface of the process film adjacent a surface of the interposer film ( 1600 ). The films are unwound ( 1602 ). The process film is fed through a process station ( 1604 ) and the first interposer film is spooled up ( 1606 ). 
     In some examples the method continues with providing a second interposer film ( 1608 ). The process film is spooled with the second interposer film, a passive surface of the process film adjacent a surface of the second interposer film ( 1610 ). The process film may be tensioned at a lesser tension than at least one of the first and second interposer films ( 1612 ). 
     In other examples, instead of spooling up the first interposer film, the process film is fed back to the first interposer film and is again spooled up with the first interposer film ( 1614 ), and no second interposer film is needed. 
     A spool of process film disposed in the protective spaces provided by the interposer film and its spacers, and with an active surface of the process film thereby protected from any contact with either the interposer film or other layers of the process film, may be enclosed in a cassette. A cassette containing such a spool can easily be transported without damaging the process film. 
     The interposer film may be fabricated of any thin compliant material, such as plastic, paper, metal, glass, composite, or the like. 
     During spooling, the interposer film can be tensioned to form the spool, and very little tension need be applied to the process film, further protecting it. The core may be rotated by a servo motor (for example, as shown in  FIG. 13B ) for precise control of speed and torque, by a hand crank (not shown) which also may offer good control of speed and torque, or some other suitable device. 
     Apparatus and methods as described make it possible to handle process films in such a way that active surfaces of the films are not touched during unwinding or winding up or white spooled. Wound-up spools of process film can easily be protected from contamination by dust and other damaging debris during transport or any time the process film is not being processed. This flexibility allows different processes to be run at different rates. Some processing, for example long-term low-temperature baking, may be done while the film is spooled up. If the spool of film is enclosed in a cassette, the cassette can readily be transported between facilities and processes outside of a clean environment. Fabrication processes can be broken down into a smaller granularity, allowing for optimization and easy process development at pilot scale or customization at volume scale. The same system can handle films of various widths, thicknesses, and moduli. Films can be spooled with independent tension between the spool formation and tension of the film, and films can be stored with low tension applied, leading to a reduction in mechanical deformation during storage. Cassettes can carry tracking, content, and process data any of which can be read without reference to the actual film, facilitating efficient process management and quality control.