Abstract:
A device is disclosed which includes a flexible material including at least one conductive wiring trace, a first die including at least an integrated circuit, the first die being positioned above a portion of the flexible material, and an encapsulant material that covers the first die and at least a portion of the flexible material. A method is disclosed which includes positioning a first die above a portion of a flexible material, the first die including an integrated circuit and the flexible material including at least one conductive wiring trace, and forming an encapsulant material that covers the first die and at least a portion of the flexible material, wherein at least a portion of the flexible material extends beyond the encapsulant material.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     This subject matter disclosed herein is generally directed to the field of packaging of integrated circuit devices, and, more particularly, to a packed IC device comprising an embedded flex circuit and various methods of making same. 
     2. Description of the Related Art 
     Integrated circuit technology uses electrical devices, e.g., transistors, resistors, capacitors, etc., to formulate vast arrays of functional circuits. The complexity of these circuits requires the use of an ever-increasing number of linked electrical devices so that the circuit may perform its intended function. As the number of transistors increases, the integrated circuitry dimensions shrink. One challenge in the semiconductor industry is to develop improved methods for electrically connecting and packaging circuit devices which are fabricated on the same and/or on different wafers or chips. In general, it is desirable in the semiconductor industry to construct transistors which occupy less surface area on the silicon chip/die. 
     In the manufacture of semiconductor device assemblies, a single semiconductor die is most commonly incorporated into each sealed package. Many different package styles are used, including dual inline packages (DIP), zig-zag inline packages (ZIP), small outline J-bends (SOJ), thin small outline packages (TSOP), plastic leaded chip carriers (PLCC), small outline integrated circuits (SOIC), plastic quad flat packs (PQFP) and interdigitated leadframe (IDF). Some semiconductor device assemblies are connected to a substrate, such as a circuit board, prior to encapsulation. Manufacturers are under constant pressure to reduce the size of the packaged integrated circuit device and to increase the packaging density in packaging integrated circuit devices. 
     The assembly of a semiconductor device and a leadframe and die ordinarily includes bonding of the die to a paddle of the leadframe, and wire bonding the bond pads on the die to the inner leads, i.e., lead fingers, of the leadframe. The inner leads, semiconductor die and bond wires are then encapsulated, and extraneous parts of the leadframe excised. In one illustrative example, the leadframe strip comprises a thin metal foil that is configured for the mounting of one or more semiconductor die, e.g., one on each die mount paddle. The leadframe strip also includes parallel spaced side rails formed with a pattern of registry holes to facilitate handling by automatic machinery. In addition, the leadframe strip includes an arrangement of inner leads configured for attachment to the bond pads of the semiconductor die during a wire bonding step. The outer leads of the leadframe strip function as the external leads of the completed semiconductor device package for connection to an external device or structure, e.g., a circuit board. The leads are connected to the side rails by dam bars, and supported thereby. The die mount paddles are typically connected to each of the side rails by a paddle support bar, extending transversely with respect to the centerline of the leadframe strip. 
     Such traditional packaging techniques and arrangements may not be able to meet the demands for more densely packaged integrated circuit devices desired by semiconductor manufacturers and their customers. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention may be understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements, and in which: 
         FIGS. 1-13  are various views of an illustrative packaged integrated circuit device that includes a leadframe and flex circuit that may be employed as described herein; 
         FIGS. 14 and 15  are cross-sectional views depicting other possible stacking arrangements of packaged integrated circuit devices using the techniques disclosed herein; and 
         FIGS. 16 and 17  depict another packaged integrated circuit device that includes an illustrative leadframe and flex circuit that may be employed as described herein. 
     
    
    
     While the subject matter disclosed herein is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. 
     Although various regions and structures shown in the drawings are depicted as having very precise, sharp configurations and profiles, those skilled in the art recognize that, in reality, these regions and structures are not as precise as indicated in the drawings. Additionally, the relative sizes of the various features and doped regions depicted in the drawings may be exaggerated or reduced as compared to the size of those features or regions on fabricated devices. Nevertheless, the attached drawings are included to describe and explain illustrative examples of the subject matter disclosed herein. 
       FIGS. 1-3  are top views depicting an illustrative leadframe  100  and flex circuit  200  that may be employed for the purposes described herein. The schematically depicted leadframe  100  shown in  FIGS. 1-3  is intended to be representative of any of a variety of different types of leadframe structures that are employed in packaging integrated circuit devices. In general, the leadframe  100  comprises a plurality of lead fingers  102  with illustrative bond pads  104  formed thereon. The exact number and arrangement of the lead fingers  102  may vary depending upon the particular application. The leadframe  100  also comprises a plurality of structures  106 , e.g., tie bars, dam bars, that, as described more fully below, may be employed in coupling the flex circuit  200  to the leadframe  100 . In the depicted embodiment, the structures  106  have a surface  106 S that may be positioned in approximately the same plane as that of the lead fingers  102 . Notably, in the disclosed example, the leadframe  100  does not employ a paddle or die support structure in the interior region  108  of the leadframe  100 . However, the present disclosure should not be considered as limited to the illustrative arrangement depicted in  FIG. 1  in which the interior region  108  is substantially free of any structure. 
     The schematically depicted flex circuit  200  is also intended to be representative of any of a variety of different flex circuit devices or materials that are commonly employed in the packaging or manufacture of integrated circuit devices or products incorporating such devices. The illustrative flex circuit  200  comprises a body  201  having a first surface  201 F and a second surface  201 S that are on opposite sides of the flex circuit  200 . The flex circuit  200  further comprises a plurality of illustrative bond pads  204  and a plurality of electrical connector arrays  205 A,  205 B that are formed on opposite ends of the flex circuit  200 . Each of the illustrative arrays  205 A comprise a plurality of electrical connectors  206 . In one illustrative example, the arrays  205  define a ball grid array assembly that is well known to those skilled in the art. Electrical connection between the bond pads  204  and an array  205  may be provided by a plurality of conductive traces  208  formed in or on the body  201  of the flex circuit  200 . The arrays  205  are provided such that one or more integrated circuit devices (not shown in  FIG. 2 ) may be conductively coupled to the flex circuit  200 , as described more fully below. Of course, the exact number, position, arrangement and layout of the arrays  205  on the flex circuit  200  may vary depending upon the particular application. In a general sense, the illustrative flex circuit  200  is a relatively flexible material that comprises at least one conductive wiring trace. 
     As shown in  FIG. 2 , the flex circuit  200  is positioned above and mechanically coupled to the leadframe  100 . In the illustrative example depicted herein, the flex circuit  200  may be mechanically coupled to the leadframe  100  by an adhesive material (not shown) that may be applied to the surfaces  106 S of the structures  106 . Of course, it should be understood that the structures  106  are intended to be representative in nature in that the flex circuit  200  may be mechanically coupled to any portion of the leadframe  100  using any of a variety of known techniques. It should also be understood that, when it is stated herein that a device or structure may be mechanically coupled or electrically coupled to another device or structure, the coupling may be accomplished by direct contact between the coupled components or one or more intermediate structures, circuits or devices may be employed to mechanically or electrically couple the components to one another. 
     As shown in  FIG. 3 , an integrated circuit device  300  is positioned above and operatively coupled to the flex circuit  200 . In one illustrative example, the integrated circuit device  300  is mechanically coupled to the flex circuit  200  using an adhesive material  305  (see  FIG. 4 ). Of course, the integrated circuit device  300  may be mechanically coupled to the flex circuit  200  using any of a variety of known techniques, e.g., tape, epoxy, etc. The illustrative integrated circuit device  300  comprises a plurality of illustrative bond pads  304  that may be employed to electrically or conductively couple the integrated circuit device  300  to other integrated circuits or devices. Traditional bonding wires  350 ,  352  may be employed to electrically or conductively couple the illustrative bond pads  304 ,  204  and  104  using any of a variety of known techniques. The integrated circuit device  300  depicted herein is intended to be representative in nature. That is, the techniques and structures disclosed herein may be employed in situations where the integrated circuit device  300  comprises any of a variety of different types of integrated circuit devices, e.g., a memory device, a logic device, a microprocessor, an application specific integrated circuit, etc. 
     Next, as shown in  FIGS. 5-7 , an encapsulant material  360  is formed in accordance with known techniques. The encapsulant material  360  covers the die  300  and portions of the flex circuit  200 . The encapsulant material  360  may be a mold compound, an epoxy, etc. The encapsulant material  360  has a first outer or top surface  361 T and a second outer or bottom surface  361 B. A first outer surface  331  of the die  300  is also depicted in  FIGS. 12-13 . One of the purposes of the encapsulant material  360  is to protect the integrated circuit device  300  and the associated electrical components connected to the device  300  from environmental or structural damage. As can be seen in  FIGS. 5 and 7 , portions of the flex circuit  200  extend beyond the encapsulant material  360 . For reference purposes, these portions are labeled as  220 A and  220 B. In the illustrative embodiment depicted herein, the portions  220 A,  220 B of the circuit  200  extending beyond the encapsulant material  360  are approximately symmetrical. However, as will be recognized by those skilled in the art after a complete reading of the present application, the portions  220 A,  220 B may be symmetrical or there may be only a single portion of the flex circuit  200  that extends beyond the encapsulant material. 
     As shown in  FIGS. 8-9 , one or more additional integrated circuit devices  400 A,  400 B may be operatively coupled to the flex circuit  200  via the arrays  205 A,  205 B, respectively. In the depicted example, the integrated circuit devices  400 A,  400 B comprise a first or top surface  404  and a plurality of conductive balls  402  (see  FIG. 9 ) that are adapted to conductively engage the structures  206  on the flex circuit  200 . Techniques for establishing such a conductive connection between the integrated circuit devices  400 A,  400 B and the flex circuit  200  are well known to those skilled in the art. Thus, the illustrative techniques depicted herein for conductively coupling such components together should not be considered a limitation of the present invention. As with the integrated circuit device  300 , the illustrative integrated circuit devices  400 A,  400 B may be any type of integrated circuit device and they can perform any electrical function. In one particular example, the integrated circuit device  400 A and/or  400 B may be an application specific integrated circuit or a controller. It should also be understood that terms such as upper, lower and the like are employed in a relative, not absolute sense. 
     Next, as shown in  FIGS. 10-13 , the flex circuit  200  is folded such that the first or top surface  404  of the integrated circuit devices  400 A,  400 B (see  FIG. 9 ) may be positioned proximate or above the other first outer surface  361 T of the encapsulant material  360 . In this illustrative example, the integrated circuit devices  400 A,  400 B are positioned in a side-by-side arrangement above the surface  361 T of the encapsulant material  360 . In an illustrative example, an adhesive material or tape  405  may be employed to secure the integrated circuit devices  400 A,  400 B to the encapsulant material  360 . Again, although two illustrative devices  400 A,  400 B are depicted in the disclosed embodiment, the subject matter disclosed herein may be employed where only a single integrated circuit device is coupled to a portion of the flex circuit  200  that extends beyond the encapsulant material  360 . Moreover, it is not required that the entirety of the integrated circuit devices  400 A,  400 B be positioned above the surface  361 T of the encapsulant material  360 . Rather, in some applications, it may be sufficient that something less than the entirety of the integrated circuit devices  400 A,  400 B may be positioned above the encapsulant material  360 . 
       FIGS. 14-15  depict alternative arrangements whereby the structures and techniques disclosed herein may be employed in stacking integrated circuit devices in a variety of different arrangements. For example, as shown in  FIG. 14 , another illustrative integrated circuit device  500  comprised of a plurality of illustrative conductive connectors  504 , e.g., a ball grid array, and a first or top surface  501 T may be positioned above and coupled, both electrically and mechanically, to the second surface  201 S of the body  201  of the flex circuit  200 . The integrated circuit device  500  may be a single device or it may be one or more devices that are separate from one another, like the integrated circuit devices  400 A,  400 B depicted in  FIG. 14   FIG. 15  depicts an illustrative arrangement whereby the surface  201 F of the flex circuit  200  may be mechanically coupled to the surface  361 T of the encapsulant material  360 , and thereafter one or more integrated circuit devices  500  may be mechanically and electrically coupled to the flex circuit  200 . As before, the illustrative integrated circuit device  500  is intended to be representative of any type of integrated circuit device. 
       FIGS. 16 and 17  depict another illustrative leadframe  100 A that may be employed with a flex circuit  200  as described herein to create a packaged integrated circuit device. As shown in  FIG. 16 , the leadframe  100 A has a plurality of extended lead fingers  102 A. In the leadframe  100 A depicted in  FIG. 16 , the bond pads  104  are asymmetrically spaced around the leadframe  100 A as compared to the leadframe  100  depicted in  FIG. 1 . In  FIG. 17 , the illustrative integrated circuit device  300 A has a plurality of bond pads  304 A that are also asymmetrically positioned around the integrated circuit device  300 A. A plurality of wire bonds  355  are employed to establish the desired electrical connection among the various components. Thus, the techniques disclosed herein may be employed in packaging integrated circuit devices  300 A having an asymmetrical pattern of bond pads  304 A.