Abstract:
An assembly for processing a flexible tape comprises a carrier frame having a slot and a cut-out region contiguous with one end of the slot for selectively transferring the flexible tape from the top surface of the carrier frame to the bottom surface of the carrier frame. An apparatus for processing the flexible tape is also disclosed and includes the carrier frame, a base having an aperture and a platform sized to fit within the aperture of the base. The base is pivotable around one end of the platform.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 09/012,590, filed Jan. 23, 1998, now U.S. Pat. No. 6,049,972 the disclosure of which is hereby incorporated by reference herein. This application claims benefit of U.S. Provisional Application Ser. No. 60/040,020 filed Mar. 4, 1997, the disclosure of which is incorporated by reference herein. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to microelectronic assemblies and more particularly relates to methods of mass producing semiconductor chip assemblies. 
     BACKGROUND OF THE INVENTION 
     A semiconductor chip is generally connected to an external circuit element through contacts on the front face of the chip. For example in the tape automated bonding process (hereinafter referred to as the “TAB” process), a dielectric sheet, such as a thin foil of polyimide, is provided with one or more bond windows and an array of metallic leads on one surface thereof. Each lead has one end integrally connected to terminals on the dielectric sheet and an opposite end extending outwardly from a central portion of the dielectric sheet so that the outermost ends of the leads project beyond the bond windows. The dielectric sheet is juxtaposed with the semiconductor chip so that the bond windows are aligned with the contacts on the chip and so that the outermost ends of the leads overlie the front face of the chip. The leads are then bonded to the contacts of the chip using bonding techniques such as ultrasonic or thermocompression bonding. After the bonding step, the terminals are connected to an external circuit element, such as a printed circuit board, which electrically interconnects the chip and the printed circuit board. 
     Commonly assigned U.S. Pat. No. 5,148,266, the disclosure of which is incorporated by reference herein, discloses a method of manufacturing semiconductor chip assemblies which are fabricated in a substantially continuous sheet or strip. A plurality of connection components are spaced lengthwise along a continuous tape, each connection component having terminals and flexible leads thereon. In one assembly method, semiconductor chips are connected to respective connection components on the tape and the assembled semiconductor chips are then carried downstream with the tape for further processing steps. 
     Commonly assigned U.S. Pat. No. 5,659,952, the disclosure of which is incorporated by reference herein, provides methods of fabricating a semiconductor chip assembly having a compliant interface. In preferred methods according to U.S. Pat. No. 5,659,952, a flexible, substantially inextensible dielectric film having a surface is provided and a plurality of compliant pads are attached to the first surface of the dielectric film, whereby any two adjacent compliant pads define a channel therebetween. Attaching the compliant pads to the dielectric film may be accomplished in a number of different ways. In one embodiment, a stencil mask having a plurality of holes extending therethrough is placed on top of the first surface of the dielectric film. The holes in the stencil mask are then filled with a curable liquid elastomer. Desirably, liquid elastomer has a thick enough consistency so that the mask may be removed before curing the elastomer. After the mask has been removed, the elastomer is at least partially cured using energy, such as heat or ultraviolet light. The holes in the mask are preferably filled with the liquid elastomer by screening the liquid elastomer across an exposed surface of the mask such that the elastomer is deposited into the holes of the mask. Thus, there is provided an assembly which includes an array or plurality of compliant pads defining channels therebetween, i.e. the channels run between adjacent compliant pads. 
     In further stages of the process disclosed in U.S. Pat. No. 5,659,952, the assembly including the array of compliant pads is assembled to a second support structure, such as a semiconductor chip having a front face with contacts. During the assembly step, the front contact bearing face of the chip is abutted against the array of compliant pads and the contacts are electrically connected to terminals on a second surface of the dielectric film remote from the chip. A compliant filler, such as a curable liquid elastomer, may then be injected into the channels between the semiconductor chip and the dielectric film and around the compliant pads while the chip and the dielectric film are held in place. The curable liquid elastomer may then be cured to form a substantially uniform, planar, compliant layer between the chip and the dielectric film. 
     However, further improvements in handling of the components during assembly processes, such as those described in U.S. Pat. No. 5,659,952, would be desirable. 
     SUMMARY OF THE INVENTION 
     In accordance with one aspect of the present invention, a method of making a microelectronic assembly includes the steps of providing a flexible tape having first and second surfaces and including a plurality or array of connection components in a central region thereof. The flexible tape typically includes a dielectric film, such as a polyimide, whereby each connection component includes a part of the dielectric film having electrically conductive parts. The flexible tape includes one or more border regions which surround the central region bearing the plurality of connection components. The electrically conductive parts typically comprise an array or plurality of conductive terminals accessible at one surface of the dielectric film and may also include flexible leads integrally connected to the terminals. Each connection component also includes an attachment region for receiving a resilient element, such as an array or plurality of compliant pads, as will be discussed in more detail below. The attachment region of each connection component are preferably provided at the first surface of the flexible tape with the terminals preferably accessible at the second surface of the flexible tape. 
     A carrier frame, having a top surface and a bottom surface, is typically provided for processing the flexible tape. The carrier frame is desirably between approximately 250-400 microns thick and comprises a rigid material, such as a metal or plastic. The carrier frame has one or more inner edges which define a slot extending between the top and bottom surfaces thereof. In certain preferred embodiments the slot is elongated and the carrier frame includes a cut-out region which is contiguous with one end of the slot, whereby the width of the cut-out region is greater than the width of the slot. 
     In further stages of preferred assembly methods, the flexible tape is placed on a top surface of a work holder and the carrier frame is placed over the flexible tape so that the second surface of the flexible tape (i.e., the terminal side) is in contact with the surface of the carrier frame. The width of the flexible tape is greater than the width of the slot. Therefore, when the flexible tape overlies the carrier frame and is substantially parallel to and in contact therewith, the side border regions of the tape preferably extend beyond the one or more of the inner edges of the carrier frame. However, the width of the cut-out region is greater than the width of the flexible tape so that portions of the flexible tape overlying the cut-out region are typically bounded by the cut-out region. 
     In further stages of the process, one end of the flexible tape is secured to the carrier frame and is preferably hingedly or pivotally secured thereto. In certain preferred embodiments, the portion of the flexible tape extending into the cut-out region is pivotally secured to the carrier frame by affixing flexible strips to the border regions of the flexible tape overlying the cut-out region. The flexible strips may be removed and desirably include an adhesive thereon which secures to the border region of the tape. In certain preferred embodiments, each flexible adhesive strip has a first end connected to the border regions of the flexible tape overlying or extending into the cut-out region and a second end connected to the carrier frame. 
     In the next stage of the process, during a first processing operation, a resilient element is provided over the attachment region of each connection component. The resilient element may be provided by forming a plurality or array of compliant pads on each attachment region, such as by using the methods described in the aforementioned U.S. Pat. No. 5,659,952. The compliant pads are preferably formed by stenciling or screen printing an array of individual pads on each attachment region, whereby the array includes channels running between adjacent pads. During the step of providing the resilient elements on the attachment regions of the connection components, the flexible tape is maintained in a substantially stationary position over the top surface of the carrier frame by supporting the underside of the flexible tape. This underside support may be provided using a supporting element, such as a support plate, which passes through the slot in the carrier frame and engages the second surface of the flexible tape to prevent the flexible tape from flexing or moving downward during the providing a resilient element step. Although the present invention is not limited by any particular theory of operation, it is believed that the formation of properly aligned and shaped resilient elements is greatly facilitated when the bottom of the stencil is in direct contact with the first surface of the flexible tape. This direct contact is not possible when the carrier frame lies between the bottom of the stencil and the flexible tape. For example, if the flexible tape was under the carrier frame, rather than overlying the top of the carrier frame, then it would be impractical to place the bottom of the stencil directly in contact with the first surface of the flexible tape because the stencil would be spaced from the first surface of the tape by the carrier frame. As mentioned previously, this could result in the formation of misaligned and improperly shaped compliant pads on the various attachment regions of the connection components. The compliant pads may then be at least partially cured, such as by using heat or ultraviolet light. In other embodiments, the compliant pads may not be cured until after die attach, as will be discussed in more detail below. 
     After the compliant pads are formed on the attachment regions of the flexible tape, the tape is preferably passed through the slot in the carrier frame by disengaging the borders of the tape from the top surface of the carrier frame, passing the tape through the slot and re-engaging the borders of the tape with the bottom surface of the carrier frame. In accordance with one preferred embodiment of the present invention, the flexible tape initially overlies the top surface of the carrier frame with the second surface of the tape in contact with the carrier frame and with one end of the tape pivotally connected to the carrier frame. Preferably, the portion of the flexible tape which is pivotally connected to the carrier frame is that portion which overlies the cut-out region of the slot. As the flexible tape is held in a substantially stationary position, one end of the carrier frame is rotated about the pivotally secured portion of the flexible tape. The carrier frame is rotated upward between approximately 15-60° and preferably between approximately 25-35° from the initial or first position toward a second position. As the carrier frame moves toward the second position, the second surface of the flexible tape disengages from the top surface of the carrier frame and passes through the slot. After the flexible tape has disengaged from the top surface and passed through the slot, the carrier frame is then rotated downward approximately 25-35° from the second position back toward the first position, and preferably all the way back to the first position, so that the bottom surface of the carrier frame engages or is in contact with the first surface of the flexible tape. During the passing the flexible tape step, the flexible nature of the tape permits the border regions of the flexible tape to move or flex toward one another so that the tape may pass freely through the slot. If the side borders of the tape were not capable of flexing inwardly, then the tape could not readily pass through the slot because, as mentioned above, the width of the flexible tape is greater than the width of the slot. After the passing step, the first surface of the flexible tape is in contact with the bottom surface of the carrier frame and the slot in the carrier frame overlies and is in substantial alignment with the central region of the flexible tape so that the slot overlies the connection components, which in turn are accessible through the slot. In this stage of the assembly process, the resilient elements on the respective connection components face upwardly in the slot. 
     In the next stage of the assembly process, during a second processing operation, microelectronic elements, such as semiconductor chips having contacts on a front face thereof, are assembled with the resilient elements of each connection component to provide microelectronic assemblies. The chips are preferably assembled to the resilient elements by abutting the chips against the resilient elements. During the assembling step, the flexible tape is maintained in a substantially stationary position, such as by using a supporting plate, to prevent the tape from flexing or moving. Supporting the underside of the flexible tape at this stage is important because if the tape flexed downward during assembly of the microelectronic elements, then the elements could possibly be misaligned over the connection components, thereby resulting in the production of defective chip assemblies. 
     After the die attach or assembly step, the microelectronic elements and the connection components are electrically interconnected, such as by bonding the flexible leads of the connection components to the contacts on the microelectronic elements, or by other known connecting processes. A curable liquid encapsulant, such as silicone elastomer, may then be provided between the microelectronic elements and the connection components. The curable liquid encapsulant preferably flows between the microelectronic element and the connection component, through the channels between the compliant pads and around the flexible leads. In certain embodiments, one or more coverlays may be used to prevent the liquid encapsulant from flowing into contact with the second surface of the connection components and/or surfaces of the chips, such as the back surfaces of the chips. The curable liquid encapsulant may then be cured using heat or ultraviolet light to provide a compliant interface for each microelectronic assembly. The cured encapsulant also protects the final assembly, including the flexible leads, from contamination. The assemblies may then be severed from the flexible tape by cutting around the perimeter of the assembly to provide individual microelectronic assemblies, or groups of two or more assemblies, capable of being interconnected with external circuit elements such as printed circuit boards. 
     In further preferred embodiments, the slot in the carrier frame is an elongated slot having first and second ends and first and second sides, and the cut-out region at one end of the slot is contiguous with either the first or second end of the slot. The flexible tape preferably includes an elongated strip having an array of connection components, such as an array of connection components aligned in a 3×10 matrix. The sides of the flexible tape are preferably bound by border regions on opposite sides thereof so that when the flexible tape overlies the carrier frame, and is substantially parallel thereto, the side border regions of the flexible tape extend beyond the sides of the elongated slot. However, the side border regions of the flexible tape extending into the cut-out region do not extend beyond the sides of the cut-out region because the width of the cut-out region is greater than the width of the flexible tape. Thus, during the pivotally securing steps described above, when the flexible strips are applied, to pivotally secure the tape to the carrier frame, the one or more strips are preferably attached to the portions of the side border regions extending into the cut-out region. Without the oversized cut-out region, it would be difficult to pass or transfer the flexible tape from one surface of the carrier frame to the opposite surface of the carrier frame while the flexible tape remained secured to the carrier frame. 
     Thus, by using a carrier frame having an elongated slot and a cut-out region as described above, it is possible to easily handle and manipulate the connection components and microelectronic assemblies through all of the assembly steps to the final severing operation. The flexible tape can be easily moved between the top and bottom surfaces of the carrier frame to provide unfettered access to the first and second surfaces of the flexible tape as required during different stages of the assembly process. The ability to quickly and easily transfer the tape from the top of the carrier frame to the bottom of the carrier frame simplifies the assembly process and minimizes handling of the flexible tape and the microelectronic elements. Moreover, the carrier frames can be readily manipulated (i.e. inverted) during the various assembly steps and are inexpensive to manufacture. 
     In another embodiment of the present invention, the carrier frame is substantially similar to that described above; however, the elongated slot includes teeth or projections which extend from opposite sides of the slot and toward the center of the slot. The side borders of the flexible tape contact the teeth to maintain the tape on the top or bottom surface of the carrier frame, as may be required during various stages of the assembly process. The flexible tape is pivotally connected to the carrier frame so that the tape can pivot between engagement with the top and bottom surfaces of the carrier frame as described above. 
     In another embodiment, an apparatus for processing flexible tape pivotally secured to a carrier frame which has a top surface and a bottom surface and a slot extending therebetween includes a base having a top surface and a bottom surface and including an aperture extending therebetween and a platform having a top surface and being sized to fit within the aperture in the base. The base is pivotally secured to one end of the platform and is movable between a first position wherein the top surface of the base is substantially parallel to the top surface of the platform and a second position wherein the top surface of the base has been pivoted between approximately 15-60°, and preferably between 25-35° above the top surface of the platform. The carrier frame includes alignment apertures and the top surface of the base includes alignment posts so that the carrier frame may be aligned over the top surface of the base, whereby the slot in the carrier frame is aligned over the aperture in the base and the platform. The apparatus also includes a clamp which has a perimeter which is sized to pass through the slot in the carrier frame and the aperture in the platform so that the clamp may secure the flexible tape to the top surface of the platform as the platform moves between the first and second positions. The platform includes a securing element at the top surface thereof, such as a plurality of vacuum holes. The clamp and the vacuum holes cooperatively secure the flexible tape to the top surface of the platform as the base pivots between the first and second positions. The top surface of the platform is approximately 500-700 microns higher than the top surface of the base when the base is in the first position. 
     The foregoing and other objects and advantages of the present invention will be better understood from the following detailed description of preferred embodiments taken together with the attached figures. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1A shows a top view of a first surface of a flexible tape including a plurality of connection components according to one embodiment of the present invention. 
     FIG. 1B shows a bottom view of FIG. 1A depicting a second surface of the flexible tape. 
     FIG. 1C shows a fragmentary side view of FIG.  1 A. 
     FIG. 2A shows a top view of a work holder for supporting the flexible tape shown in FIGS.  1 A- 1 C. 
     FIG. 2B shows a side view of FIG.  2 A. 
     FIG. 3A shows a top view of the flexible tape shown in FIGS.  1 A- 1 C on the work holder shown in FIGS.  2 A- 2 B. 
     FIG. 3B shows a side view of FIG.  3 A. 
     FIG. 4A shows a top view of a carrier frame used in one embodiment of a method of making microelectronic assemblies according to the present invention. 
     FIG. 4B shows a side view of FIG.  4 A. 
     FIG. 5A shows a top view of the carrier frame shown in FIGS.  4 A- 4 B overlying the flexible tape shown in FIGS.  1 A- 1 C and the work holder shown in FIGS.  2 A- 2 B. 
     FIG. 5B shows a side view of FIG.  5 A. 
     FIG. 6 shows a top view of FIG. 5A after the flexible tape has been pivotally connected to the carrier frame. 
     FIG. 7 shows a detailed fragmentary view of the end of the flexible tape pivotally connected to the carrier frame. 
     FIG. 8A shows a top view of the pivotally connected flexible tape shown in FIGS. 6 and 7 after the carrier frame has been inverted. 
     FIG. 8B shows a side view of FIG.  8 A. 
     FIG. 9A shows a front view of a storage magazine used for storing the pivotally connected flexible tape shown in FIGS. 8A and 8B 
     FIG. 9B shows a detailed fragmentary view of the storage magazine shown in FIG.  9 A. 
     FIG. 10A shows the orientation of the flexible tape and the carrier frame shown in FIG. 8B after the carrier frame has been removed from the storage magazine. 
     FIG. 10B shows a fragmentary side view of the flexible tape while compliant pads are being formed on the first surface thereof. 
     FIG. 10C shows a top fragmentary view of the flexible tape shown in FIG. 10B after the compliant pads have been formed thereon. 
     FIG. 11 shows a perspective view of a pivoting apparatus for processing the flexible tape shown in FIGS.  1 A- 1 C. 
     FIGS. 12A and 12B show respective top and side views of a work holder for the pivoting apparatus shown in FIG.  11 . 
     FIGS. 13A and 13B show respective side and end views of a clamp for the pivoting apparatus shown in FIG.  11 . 
     FIG. 13C shows the clamp shown in FIG. 13B in contact with the top surface of the flexible tape shown in FIGS.  1 A- 1 C. 
     FIG. 14A shows a top view of the flexible tape and carrier frame of FIG. 10A overlying the work holder shown in FIG.  12 A. 
     FIG. 14B shows a side view of FIG.  14 A. 
     FIG. 15A shows a top view of FIG. 14A including the clamp shown in FIGS. 13A and 13B. 
     FIG. 15B shows a side view of FIG.  15 A. 
     FIGS. 16A and 16B show the pivoting assembly of FIG. 15B during further stages of a method for passing the flexible tape through a slot in the carrier fame. 
     FIG. 17A shows a top view of the flexible tape after is has been passed through the slot in the carrier frame. 
     FIG. 17B shows a fragmentary side view of FIG.  17 A. 
     FIG. 18 shows the flexible tape of FIG. 17A after the carrier frame has been inverted. 
     FIG. 19 shows the flexible tap shown in FIG. 18 during further stages of an assembly method according to the present invention. 
     FIG. 20 shows a fragmentary side view of FIG. 19 during further stages of an assembly method according to the present invention. 
     FIG. 21 shows another embodiment of the carrier frame shown in FIG.  4 A. 
     FIG. 22 shows an inverted view of FIG. 20, during still further stages of an assembly method according to the invention. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring to FIGS.  1 A- 1 C, in one embodiment of the present invention a flexible tape  20  includes a flexible sheet-like dielectric film, such as a polymeric material, and has a first surface  22  and a second surface  24 . The flexible tape includes a plurality of connection components  26  which are arranged in a 3×10 array. The flexible tape strip  20  is provided by severing a section of the tape from a continuous reel. Each connection component  26  includes a part of the flexible dielectric film having an attachment surface  27  at the first surface  22  of the flexible tape and a plurality or array of terminals  28  at the second surface of the flexible tape. Each connection component  26  also includes flexible leads  30  integrally connected to the terminals  28 . Each connection component  26  serves as a compliant interface for a microelectronic element (not shown), such as a semiconductor chip, so that the microelectronic element may be electrically connected to an external circuit element via the connection component  26 . The connection component  26  is preferably formed from a polymeric material such as KAPTON(E) available from DuPont Chemical Corporation having an approximate thickness between 25 to 75 microns. The connection component  26  includes bond windows  29  for accessing the flexible leads  30  in order to bond the flexible leads  30  to contacts on the microelectronic element during a bonding operation, as will be discussed in more detail below. The array of connection components  26  are disposed within a central region of the flexible tape  20 . The tape  20  has a first end  32  and a second end  34  and side portions which are bounded by a first border  36  and a second border  38 . The side borders  36  and  38  include sprocket holes  40  formed therein for handling and moving the flexible tape  20  during fabrication of the tape and during the various assembly steps. 
     FIGS. 2A and 2B show a work holder  42  for supporting the flexible tape  20  during certain stages of the assembly process. The work holder  42  includes an array of vacuum holes  44  formed at the top surface  46  of the work holder  42 . When the flexible tape  20  is placed on the top surface  46  of the work holder  42 , the vacuum holes  44  are preferably in substantial alignment with the central region of the flexible tape  20 . The work holder  42  also includes a first set of tape alignment posts  48  and a second set of tape alignment posts  49  for aligning the flexible tape  20 . During an alignment operation, two or more of the sprocket holes  40  are aligned with the tape alignment posts  48  and  49  as the flexible tape  20  is lowered onto the top surface  46  of the work holder  42 . The flexible tape  20  may be removed from the top surface of the work holder  42  and realigned if visual observation indicates that the flexible tape  20  has not been properly aligned on the work holder  42 . The work holder  42  also includes a set of carrier frame alignment posts  50  projecting from the top surface thereof. The carrier frame alignment posts  50  are used to align the carrier frame over the work holder, as will be described in more detail below. 
     FIGS. 3A and 3B show the flexible tape  20  after the tape has been aligned with the tape alignment posts  48  and  49  positioned on the work holder  42 . The flexible tape  20  is positioned on the work holder  42  so that the first surface  22  of the flexible tape  20  is in contact with the top surface  46  of the work holder  42  and the second surface  24  of the tape  20  faces away from the top surface  46  of the work holder  42 . 
     Referring to FIGS. 4A and 4B, in the next stage of the assembly process, a carrier frame  52  having a top surface  54  and a bottom surface  56  and including an elongated slot  58  formed in the center thereof is provided. The slot  58  has a first end  60  and a second end  62  and first and second opposed sides  64  and  66  which are defined by one or more interior edges  70  of the carrier frame  52 . The carrier frame  52  also includes a cut-out region or portion  72  integral with the second end  62  of the slot  58 . The width of the cut-out portion  72  is greater than the width of the slot  58  for reasons which will be explained in more detail below. The carrier frame includes tape alignment apertures  74  and  75  for receiving the respective flexible tape alignment posts  48  and  49  of the work holder when the carrier frame  52  is placed over the work holder  42  and a second set of apertures  76  for receiving the carrier frame alignment posts  50 . 
     FIGS. 5A and 5B show further stages after the carrier frame  52  has been provided over the second surface of the flexible tape  20  and the work holder  42 . During this step, the top surface  54  of the carrier frame  52  is juxtaposed with the top surface  46  of the work holder  42 . The slot  58  in the carrier frame  52  overlies the central region of the flexible tape  20  including the plurality of connection components  26 . Before the carrier frame  52  is positioned over the work holder  42 , the flexible tape alignment posts  48  and  49  are aligned with the respective tape alignment apertures  74  and  75  in the carrier frame  52  and the carrier frame alignment posts  50  are aligned with the carrier frame alignment apertures  76  in the carrier frame  52 . The carrier frame  52  is then lowered into engagement with the top surface  46  of the work holder  42  so that the top surface  54  of the carrier frame  52  is in contact with the second surface  24  of the flexible tape  20 . The width of the flexible tape  20  is greater than the width of the slot  58  so that the side borders  36  and  38  extend beyond the sides  64  and  66  of the slot  58 . However, the second end  34  of the flexible tape  20  which extends into the cut-out region  72  is bounded by the cut-out region so that the borders are visible and can be accessed from the bottom of the carrier frame  52 . 
     Referring to FIGS. 6 and 7, the second end  34  of the flexible tape  20  is then pivotally connected to the carrier frame  52  by placing flexible strips, such as polyimide tape strips  80 , on the border regions  36  and  38  of the flexible tape  20  which extend into the cut-out region  72 . FIG. 7 shows a fragmentary view of the carrier frame  52  including the polyimide tape strips  80  attached to the borders  36  and  38  of the flexible tape  20  extending into the cut-out region  72 . The first ends of the tape strips  80  are attached to the flexible tape  20  and the second ends of the adhesive strips  80  are attached to the carrier frame  52  adjacent the cut-out region  72 . 
     Referring to FIGS. 8A and 8B, after the flexible tape  20  has been pivotally connected to the carrier frame  52  by the adhesive strips  80 , the carrier frame is lifted off of the work holder and the carrier frame  52  is inverted so that the top surface  54  of the frame and the first surface  22  of the flexible tape  20  (i.e., the surface bearing the attachment surfaces  27  of the connection components  26 ) face upwards. The second surface  24  of the flexible tape  20  remains in contact with the top surface  54  of the carrier frame  52 . 
     Referring to FIGS. 9A and 9B, the carrier frame  52  including the flexible tape  20  is then loaded into a storage magazine  82  for storing the flexible tape  20  until it is needed for further assembly steps. The magazine  82  has a plurality of slots  84 . As shown in FIG. 9B, each slot is defined by lower ledges  85  and upper ledges  87  facing the lower ledges. The lower ledges are provided with recesses  89  about 0.025 inches deep. The recesses provide clearance for the flexible strips  80  so that the strips  86  are not damaged by the slots  84  when the carrier frame  52  is stored in the magazine  82 . In other preferred embodiments, the carrier frame  52  is not rotated after the flexible strips  86  are attached to the flexible tape  20 . In these embodiments, the carrier frames  52  are directly loaded into the magazine slots  84  for storage and after a predetermined number of carrier frames have been stored inside the magazine  82 , the entire magazine is rotated so that the first surfaces  22  of the flexible tapes  20  face upward. 
     In the next stage of the assembly process, the carrier frame is removed from the storage magazine  82  and oriented as shown in FIG. 10A so that the flexible tape  20  overlies the top surface  54  of the carrier frame  52 . In this particular orientation, the top surface  22  of the tape  20  faces away from the carrier frame  52  and the second surface  24  of the tape  20  is in contact with the carrier frame  52 . A supporting plate  91  is provided through the slot in the carrier frame to support the flexible tape  20  from flexing during further assembly steps as will be discussed below. 
     Referring to FIG. 10B, resilient elements may then be formed on the first surface  22  of the flexible tape  20  according to the embodiments disclosed in the aforementioned U.S. Pat. No. 5,659,952. Each resilient element preferably includes a plurality or array of compliant pads  88  which are desirably stencil printed over the attachment regions. When the resilient elements are provided on the flexible tape  20 , it is critical that the flexible tape  20  overlies the top surface  54  of the carrier frame  52  so that the bottom surface  93  of a stencil  95  used to form the resilient elements may be flush against the first surface  22  of the flexible tape  20 . As mentioned above, if the flexible tape  20  were in contact with the bottom surface  56  of the carrier frame  52 , the thickness of the carrier frame  52  would prevent the bottom surface  93  of the stencil  95  from being flush with the first surface  22  of the flexible tape  20  which would adversely affect the alignment and the shape of the resilient elements. The supporting plate  91  prevents the flexible tape  20  from flexing when the compliant pads  88  are stencil printed thereon. After the compliant pads  88  have been provided on the top surface  22  of the flexible tape  20 , the stencil  95  is removed and the compliant pads  88  are later cured as disclosed in U.S. Pat. No. 5,659,952. FIG. 10C shows a top view of one connection component  26  of the flexible tape  20  after the compliant pads  88  have been formed thereon. 
     Before curing, the carrier frames, with tapes and resilient elements thereon, are loaded into storage magazines identical to or substantially similar to those shown in FIG.  9 A. The utilization of the storage magazine facilitates handling of the flexible tapes  20  during the curing processes and isolates the tapes from one another when they are stored in the magazine. The entire magazine can be moved into and out of a curing oven without extraordinary care in handling. After curing the resilient elements, the flexible tape  20  may then be transferred to the bottom surface of the carrier frame  52  in order to complete further assembly steps, as will be discussed in more detail below. 
     FIG. 11 shows a perspective view of a pivoting apparatus used in conjunction with the carrier frame  52  described above for passing the flexible tape  20  through the slot  58  in the carrier frame  52 . The pivoting apparatus  142  includes three separate elements: a base  190  which pivots upwards and about an axis designated A—A; a vacuum platform  192  having vacuum holes  144 , and a clamp  194  which is initially in an open or raised position directly above the vacuum platform  192 . Referring to FIGS. 12A and 12B, the vacuum platform  192  is sized to fit in the center of the base  190  so that the base  190  can rotate about one end of the vacuum platform  192  along axis A—A. Initially, the top surface of the vacuum platform  192  in the center of the base  190  is approximately 500-700 microns higher than the top surface  146  of the base  190 . As shown in FIGS. 13A and 13B, the clamp  194  includes contact ribs  196  which extend from one surface of the clamp  194  on opposite sides thereof. Referring to FIG. 13C, the clamp  194  is preferably sized to fit inside the center of the base  190  and the slot in the carrier frame  52  so that the clamp  194  may remain in contact with the flexible tape  20  as the base  190  pivots about one end of the flexible tape  20 . 
     Referring to FIGS. 14A and 14B, the carrier frame  52  is then aligned with the carrier frame alignment posts  150  on the base  190  and positioned in contact with the top surface  146  of the base  190  so that the bottom surface  56  of the carrier frame  52  engages the top surface  146  of the base  190 . In this particular orientation, the first surface  22  of the flexible tape  20  faces upward and away from the top surface  54  of the carrier frame  52 . A vacuum is then activated through the vacuum holes  144  in the vacuum platform  192  so that the second surface  24  of the flexible tape  20  is adhered to the vacuum platform  192 . As shown in FIGS. 15A and 15B, the clamp  194  is lowered until the contact ribs  196  thereon engage the flexible tape  20  adjacent the border regions  36  and  38  of the flexible tape  20 . The contact ribs  196  are preferably positioned so that the ribs  196  do not engage the connection components  26  or the resilient elements formed on the connection components. The clamp  194  and the vacuum cooperatively secure the flexible tape  20  in a stationary position on the pivoting apparatus. Referring to FIG. 16A, in the next stage of the operation, while the flexible tape  20  is held stationary between the clamp  194  and the vacuum platform  192 , the base  190  and the carrier frame  52  are rotated upward from a first position  198 A to a second position  198 B, by pivoting the base  190  and the carrier frame  52  about the A—A axis (shown in FIG.  11 ). In one embodiment, the base  190  and the carrier frame  52  are rotated upward between approximately 20-40°. As the carrier frame  52  is rotated upward, the borders  36  and  38  of the flexible tape  20  disengage from the top surface  54  of the carrier frame  52  and the flexible tape  20  passes through the slot  58 . Referring to FIG. 16B, the carrier frame  52  and the base  190  are then rotated downward back to the first position  198 A so that the bottom surface  56  of the carrier frame  52  is in contact with the first surface  22  of the flexible tape  20  and the slot  58  overlies the central region of the flexible tape  20  including the connection components  26  therein. 
     FIGS. 17A and 17B show the flexible tape  20  after the tape  20  has passed through the slot  58  in the carrier frame  52  and after the carrier frame has been off-loaded from the work holder  42 . At this stage, the first surface  22  of the tape  20  is in contact with the bottom  56  of the carrier frame  52  and the slot  58  overlies the connection components  26  and the compliant pads  88  formed on the connection components. 
     Referring to FIGS. 18 and 19, the carrier frame  52  is then inverted so that the bottom surface  56  of the carrier frame  52  and the second surface  24  of the flexible tape  20  face upward. Referring to FIG. 19, additional adhesive strips  80 ′ are then placed over the side borders  36  and  38  of the flexible tape  20  to prepare the tape for further stages of the process during which microelectronic elements, such as semiconductor chips having electrical contacts on a front face thereof, will be assembled with the connection components of the flexible tape. 
     FIG. 20 shows a fragmentary side view of later stages of the assembly process during which semiconductor chips  102  are assembled to the compliant pads  88  on the first surface  22  of the flexible tape  20 . Before the semiconductor chips  102  are assembled to the flexible tape  20 , a supporting plate  191  is preferably placed through the slot  58  in the carrier frame  52  so that the supporting plate  191  engages the second surface  24  of the flexible tape  20 . After the supporting plate  191  is in place, the semiconductor chips  102  are assembled with the connection components  26  by abutting the front contact bearing faces  104  of the chips  102  against the compliant pads  88  of each connection component  26 , whereby the supporting plate  191  prevents undesirable movement and flexing of the flexible tape  20  during the die attach operation. 
     After die attach, the carrier frame is inverted once again so that the second surface of the flexible tape is accessible for bonding the flexible leads to the contacts on the chip. A curable liquid encapsulant may then be introduced between the chips and the connection components as described in U.S. Pat. No. 5,659,952 and the encapsulant cured, using energy such as heat or ultraviolet light, to provide a compliant interface for the chip packages. After the encapsulant is cured, the assemblies may be severed from one another to provide individual microelectronic assemblies. In certain preferred embodiments, one or more coverlays may be provided over the exterior surfaces of the assemblies while the curable liquid encapsulant is introduced to prevent the encapsulant from contacting the exterior surfaces thereof as disclosed in U.S. patent application Ser. No. 08/726,697, the disclosure of which is incorporated by reference herein. 
     Typically, before the flexible tape is severed to provide individual assemblies, solder balls are attached to the terminals at the second surface of the flexible tape. Attachment of the solder balls enables the terminals to be electrically connected to an external circuit element, such as a printed circuit board (PCB). One preferred method for attaching solder balls includes providing a flux material over the terminals, such as by using a stencil having an array of holes extending therethrough. After the array of holes are aligned over the terminals, the flux is forced through the holes to form flux pads over each of the terminals. Solder balls are then placed on the array of flux pads using a second stencil fixture having a plurality of holes. A sweeper plate may be used to sweep the solder balls over the matrix of holes. 
     After the solder balls have been disposed on the flux pads the solder balls are reflowed to form a permanent bond with the terminals. There are a number of methods which can be used to reflow solder balls. In one preferred embodiment, the flexible tape including the solder balls is placed on a belt which passes the flexible tape through a furnace. In the furnace, the solder balls are heated above a reflow temperature or melt point and maintained at that temperature for approximately 30-45 seconds. The solder balls are then cooled down below the reflow temperature at which point the solder balls solidify. The flexible tape and reflowed solder balls may then be processed to remove excess flux therefrom. The flux removal process, generally referred to as defluxing, can be either a manual procedure or a fully automated procedure. In accordance with one preferred manual procedure, the flexible tape bearing the reflowed solder balls is immersed in liquid alcohol for one minute in order to soften the excess flux at the terminal sites and the flexible tape and terminals are then scrubbed with a brush to remove the excess flux therefrom. 
     Referring to FIG. 21, in another embodiment, the carrier frame  252  has a slot  258  therein which includes a plurality of teeth  259 . The plurality of teeth  259  extend from opposite sides of the slot  258 , toward the center of the slot  258 . The side borders of the flexible tape (not shown) preferably contact the teeth  259  to maintain the tape on the top or bottom surface of the carrier frame, as may be required during the various assembly steps described above. 
     As will be appreciated, numerous variations and combinations of the features discussed above can be utilized without departing from the present invention as defined by the claims. Accordingly, the foregoing description of the preferred embodiments should be taken by way of illustration rather than by way of limitation of the invention.