Abstract:
A semiconductor package can comprise a die stack attached to a substrate, with bond wires electrically connecting the two. Often multiple die stacks are adhered to a single substrate so that several semiconductor packages can be manufactured at once. A molding compound flow controller is optimally associated with the substrate or semiconductor package at one or more various locations. Flow controllers can control or direct the flow of the molding compound during the encapsulation process. Flow controllers can be sized, shaped, and positioned in order to smooth out the flow of the molding compound, such that the speed of the flow is substantially equivalent over areas of the substrate containing dies and over areas of the substrate without dies. In this manner, defects such as voids in the encapsulation, wire sweeping, and wire shorts can be substantially avoided during encapsulation.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
       [0001]    This is a divisional of co-pending U.S. patent application Ser. No. 11/620,553 filed Jan. 5, 2007. 
     
    
     FIELD 
       [0002]    The disclosure concerns packaging for semiconductors. 
       BACKGROUND 
       [0003]    Manufacturers consistently try to reduce the size of products, such as cellular telephones, computers, and digital cameras in order to meet consumer demands. All of these electronic products require integrated circuit (IC) assemblies. Thus, it is important to continue to reduce the size of these IC assemblies, without sacrificing performance, in order to reduce the overall product size. 
         [0004]    IC assemblies may include a plurality of interconnected IC chips, which also are referred to as dies. One or more dies are stacked in a particular location on a substrate surface. The substrate location is referred to as a die attach area. Typically, an array of such die stacks is formed on a substrate, and the die stacks are separated into individual packages along saw lines to form the end-product. For convenience, this specification typically refers to plural dies; however, all statements apply equally to a semiconductor package having only one die. 
         [0005]    A die stack is referred to as a single stack if there is a single die stacked in a particular location on the substrate. If plural dies are stacked on top of each other in a particular location on the substrate, the stack is referred to as a multiple stack. A semiconductor package can comprise one die stack (whether a single or multiple stack). Alternatively, a semiconductor package can comprise more than one die stack, and some or all of the stacks can be single stacks, while some or all of the stacks can be multiple stacks. 
         [0006]    Dies typically are physically coupled to the substrate via an adhesive layer. Each die also is effectively electrically connected to the substrate. This electrical connection can be created using thin conductive wires, such as gold wires or aluminum wires. Alternatively, dies can be electrically connected to the substrate via small solder balls, using, for example, the flip chip method. These and other methods are well known in the industry. The area where dies are electrically coupled to the substrate can be referred to as the conductive element bonding area or, in the case where wire bonds are present, as the wire bonding area. Dies are first electrically connected to the substrate as desired, and then the die substrate assembly is encapsulated by a protective molding compound, usually comprising a polymer, ceramic, epoxy, or combinations thereof. Encapsulation protects the dies and electrical connections by creating a moisture barrier to prevent physical, chemical and/or electrical damage to the components. 
         [0007]    The substrate, die stack, and encapsulating material combine to form a “package.” A cross sectional drawing of a representative prior art package  100  is illustrated in  FIG. 1 . Illustrated package  100  comprises a substrate  102  and four stacked dies  104 ,  106 ,  108 ,  110  attached to substrate  102  or to another die, via die adhesive layers  103 ,  105 ,  107 , and  109 . Package  100  further comprises solder balls  112  along one surface of substrate  102 . Solder balls  112  provide input and output access to dies  104 ,  106 ,  108 , and  110  once package  100  is connected to a circuit board for use in an electronic product. Semiconductor package  100  has been encapsulated with molding compound  114 . Plural conductive bond wires  118  electrically couple each die  104 ,  106 ,  108 , and  110  to substrate  102 . 
         [0008]    Numerous different packages  100  are known and used in the art. Some common examples include the polymer ball grid array package, such as the plastic ball grid array (PBGA) package, and the fine ball grid array (FBGA) package. The package also can include a heat spreader, which covers the dies and conductive wires, in order to improve heat transfer, such as during the encapsulation process. Although semiconductor packages, such as package  100 , are widely used, however problems still exist with the encapsulation process. 
         [0009]    Still with reference to  FIG. 1 , during the encapsulation process, a mold is placed over dies  104 ,  106 ,  108 , and  110  and substrate  102 , leaving a small gap  116  between the top of molding compound  114  and the top of die  110 . Gap  116  is herein referred to as the encapsulant gap  116 , and also represents the distance between the top of die  110  and the package surface once encapsulation is complete. Once the mold is in place, a molding compound  114  is injected into the mold, and flows over dies  104 ,  106 ,  108 , and  110  inside the mold. Molding compound  114  typically is injected at a temperature high enough that molding compound  114  is in a liquid or semi-liquid state, and therefore flows over dies  104 ,  106 ,  108 , and  110  and substrate  102 . Molding compound  114  then cools and hardens to protect substrate  102 , dies  104 ,  106 ,  108 , and  110 , and electrical connections, such as bond wires  118 . 
         [0010]    The encapsulant gap has a significant impact on the molding process. As mentioned above, manufacturers need to keep package size as small as possible, even though dies often are stacked to create IC assemblies to use space most efficiently. As dies are stacked, the encapsulant gap decreases. But as the encapsulant gap decreases, molding compound flow is affected and can become uneven. As a result, various defects in the finished product, such as internal and external voids, wire sweeping, and wire shorts, can occur. Internal and external voids are essentially areas where air has been trapped by molding compound (where air fails to escape), resulting in holes or voids in the package. External voids can subject the device to moisture damage, which can ruin the device. Internal voids may expand if exposed to heat and eventually cause the package layers to separate. In semiconductor packages containing bond wires, another potential problem during the molding process is wire sweeping, where molding compound deforms or breaks the conductive wires, or causes two different bonding wires to contact, creating electrical shorts in the device. 
         [0011]    Devices do exist ostensibly designed to reduce air pocket formation. For example, see U.S. Pat. No. 6,969,640 to Dimaano et al., which discloses an “air pocket resistant semiconductor package system.” Dimaano discloses using individual heat spreaders placed around each die. Each heat spreader has an encapsulant guide and an air vent, to prevent air pocket formation. 
         [0012]    Additionally, U.S. Pat. No. 6,750,533 to Wang et al., discloses a “substrate with dam bar structure for smooth flow of encapsulating resin.” Wang&#39;s  FIG. 1  shows a plan view of a semiconductor package comprising dam bar  56  on substrate  5 . “The dam bar  56  formed on the substrate  5 , as shown in  FIG. 1 , is preferably provided with a first gate  560  directed toward the molding gate  55 , a second gate  561 , and a third gate  562  opposed to the second gate  561 , wherein the second and third gates  561 ,  562  are vertically arranged in position with respect to the molding gate  55 ; this allows the dam bar  56  to be divided into four sections by means of the first, second and third gates  560 ,  561 ,  562 .” Column  4 , line  66  through column  5 , line  6 . “The first gate  560  is sized smaller than the second and third gates  561 ,  562  respectively.” Column  5 , lines  7 - 8 . “The geometry, shape and height of the dam bar  56  are critical factors for affecting mold flow of the encapsulating compound.” The molding compound is “impeded by the dam bar  56 , and diverts to flow through the second and third gates  561 ,  562 .” Column  5 , lines  20 - 21 . 
         [0013]    As shown in [Wang]  FIG. 3A , a simple dam bar  56   a  is formed with a gate  560   a  directed toward the molding gate  55 , and has found to be ineffective for impeding mold flow of the molding compound.” Column  5 , lines  51 - 54 . “A dam bar  56   b  of [Wang]  FIG. 3B  is similar in structure to the dam bar  56   a  of [Wang]  FIG. 3A , with the difference in that the dam bar  56   b  is dimensioned with increased length, and a gate  560   b  of the dam bar  56   b  is sized smaller than the gate  560   a  of the dam bar  56   a . It has been found that, such a dam bar  56   b  would reduce a flowing speed of the molding compound.” Column  5 , lines  55 - 60 . Thus, the properly sized gate is identified as a critical factor by Wang. 
         [0014]    Wang  FIG. 4  shows a plan view of a semiconductor package comprising dam bar  65  positioned on substrate  6 , with flow of the molding compound indicated by the arrow. However, as positioned in Wang  FIG. 4 , dam bar  65  does not appear capable of controlling the flow of molding compound over each of the chips  63 . For example, dam bar  65  is not positioned to effectively control molding compound flow over chip  63 . 
         [0015]    Moreover, Wang discloses only curvilinear or rectangular dam bars geometry, as illustrated in Wang  FIG. 1 ,  3 A,  3 B, and  4 . The height of the dam bar disclosed in Wang must be at least 75% of the height of the mold cavity. The dam bar impedes molding compound flow by forcing the molding compound through the gates of the dam bar. Column  6 , lines  18 - 30 . As such, the dam bars disclosed in Wang are not well-suited for use in an arrayed semiconductor package with saw lines. 
         [0016]    The prior art does not address all potential problems associated with molding compound flow and the encapsulation process. For example, known devices and methods do not effectively control molding compound flow over all areas of the semiconductor package. 
       SUMMARY 
       [0017]    Molding compound typically flows more slowly over dies than it does over substrate areas lacking dies. Where there is no die stack, the encapsulant gap is the entire distance between the substrate and package surface, as opposed to the distance between the top of the die stack and the package surface, where there is a die stack. As a result, the leading edge of molding compound flow deviates from a straight line. Molding compound flow deviation is smallest at the beginning of the flow process, increases as it flows over the surface, and is at the maximum at the end of the encapsulation process. These large deviations can result in the encapsulation defects discussed above. 
         [0018]    To facilitate molding compound flow during encapsulation, one embodiment of a disclosed semiconductor package comprises a substrate, a die electrically coupled to the substrate, and a flow controller effectively sized and positioned to control flow of a molding compound. Plural flow controllers also can be provided. Any embodiment can additionally optionally include a passive component or plural passive components. Flow controllers as disclosed and claimed herein are not taught by the prior art discussed above. For example, with the claimed embodiment, molding compound flows over and about the flow controllers during the encapsulation process, as opposed to through gates. In some embodiments, flow controllers facilitate effective molding compound flow to, for example, reduce encapsulation defects such as air voids, wire sweeping, and wire shorts. Flow controllers also can divert molding compound flow from a particular area or direct molding compound flow to a particular area if desired. 
         [0019]    Generally, the material used to produce flow controllers is not a solid at the time of positioning, but instead typically has a viscosity from about 2,000 to about 6,000 (centipoise cP) at 25° C. Before the molding process takes place, flow controllers may solidify, in order to maintain their position during encapsulation. Materials with a higher viscosity can be used to help prevent, or can comprise adhesive on a portion thereof, flow controllers from contacting elements within the semiconductor package. Flow controllers can be composed of a single material or can comprise any number of materials, including die adhesive (e.g. epoxy with silicon or Teflon filler), die coating material (e.g. polyimide), polymeric materials, screen printing materials, solder paste (e.g. Sn, SnAgCu), or combinations thereof. Flow controllers can comprise a non-insulating material. Flow controllers can comprise adhesive material, to allow for direct attachment to a desired surface or component, such as the substrate. Alternatively, flow controllers may comprise a composite, where a layer of adhesive material is applied to a surface within the package and a polymer or “dummy” block is coupled to the layer of adhesive, in order to control molding compound flow. Dummy blocks provide certain advantages in the claimed products and processes, such as reducing the need to use larger amounts of adhesive material to control flow over a large area of the substrate. 
         [0020]    Molding compound flow controllers can be used in any semiconductor package. Embodiments can be implemented with a semiconductor package comprising a single die, plural dies, and/or an array of dies. A semiconductor package comprising an array of dies can have single stacks and/or multiple stacks. Flow controllers can be applied to a package at any point during the process of making the semiconductor package, such as before, during, or after die attachment, or, in packages which contain wire bonds, before, during, or after wire bonding. Flow controllers can be positioned and applied using any suitable technique, including without limitation, epoxy dispensing and attach systems, epoxy dotting and attach systems, die coating, or screen printing. 
         [0021]    Flow controllers can be positioned as desired within the semiconductor package to facilitate encapsulation over all active components coupled to the substrate. Flow controllers can be coupled to the substrate, dies, and/or any other structures within the package. Alternatively, flow controllers can be positioned such that they are coupled to any interposers that may be present within the semiconductor package. 
         [0022]    The numbers, sizes, shapes, and locations of flow controllers can be selectively determined and optimized based on die and/or bond wire layout in a particular package. Flow controllers can take any shape, such as substantially rectangular, cubic, spherical, cylindrical, conical, or pyramidal. Flow controllers also can be amorphous, or can comport to the shape of components and structures. When a semiconductor package comprises plural flow controllers, each flow controller may be the same, or may be a different shape, size, and/or composition. 
         [0023]    Flow controller dimensions and position can be determined by any appropriate method, such as by trial and error, with computer software, or via a remote computer. Any embodiment can be implemented by a computer, such as by executing instructions for flow controller positioning contained by computer readable media. Flow controllers can be positioned in a symmetrical or asymmetrical fashion relative to other package components. They can be positioned on one side or on multiple different sides of the dies. When plural flow controllers are positioned, they can be positioned independently of one another. 
         [0024]    In some embodiments, flow controllers can be positioned so that they do not contact the dies. Alternatively, flow controllers can contact the dies, any bond wires present and/or the substrate space in between the die stacks. A flow controller can be positioned such that at least a portion of the flow controller is within a perimeter defined by the dies, between adjacent dies, and/or within a perimeter defined by conductive elements. When the semiconductor package comprises an array of dies, flow controllers can be positioned outside a perimeter defined by the array or, alternatively, within a perimeter defined by the array. Further, in embodiments including saw lines between individual die stacks, flow controllers can be positioned such that they extend over the saw lines, covering the entire distance between die stacks. Alternatively, flow controllers can be positioned so that they are not continuous between the die stacks, in that there is an interruption in flow controller material at the locations of saw lines. In this manner, flow controllers will not be visible on the side edges of the semiconductor packages after singulation. 
         [0025]    In semiconductor packages further comprising bonding wires, flow controllers can be small enough to be positioned between adjacent bonding wires, and/or substantially within a perimeter defined by the bond wires. In this embodiment, the flow controller may be positioned such that it does not contact the bonding wires or a die. Alternatively, a flow controller can be positioned such that it does contact bond wires, or a flow controller may substantially embed a bond wire or wires. In one embodiment, a single flow controller may constitute a single integrated body which contacts the surfaces of the substrate, bond wires, and dies. As another option, flow controllers can be positioned outside the perimeter defined by the bonding wires. In other embodiments, flow controllers can be located such that a portion of a flow controller is located within the perimeter defined by the bond wires, and a portion of the same flow controller is located outside the perimeter defined by the bond wires. Flow controllers can be coupled to the substrate in any and all of these embodiments. 
         [0026]    When a single package contains more than one flow controller, multiple flow controllers can be arranged as desired. For example, in one embodiment, some flow controllers can be located outside a perimeter defined by the bond wires, while others can be located within a perimeter defined by the bond wires. In another embodiment, a flow controller can be located such that a first portion is within the perimeter defined by the bond wires, while a second portion is outside the perimeter defined by the bond wires, and while a second flow controller can be positioned entirely outside the perimeter defined by the bond wires. In yet another embodiment, a flow controller can be located such that a first portion is within the perimeter defined by the bond wires, while a second portion is outside the perimeter defined by the bond wires, and while a second flow controller can be positioned entirely within the perimeter defined by the bond wires. Additionally, in some embodiments, all three of these general positions could be present within a single semiconductor package. 
         [0027]    Flow controller height can be selected to optimize control of molding compound flow, and can be much smaller than that of the dies, substantially the same as that of the dies larger than the dies, or any size in between. Furthermore, if plural flow controllers are used, each can have different size and/or shape, all can have the same size and/or shape, or any and all combinations of shape and size. At a minimum, flow controller height can be any dimension greater than zero which still allows for functionality as a flow controller. The upper limit of flow controller height is determined by molding compound thickness. If flow controllers extend above the top of the molding compound, damage to the molding tool is possible. A relatively thin flow controller may require greater surface area to have the same impact on molding compound flow, as flow controller volume may be a factor for controlling molding compound flow. In commercial embodiments, the minimum flow controller volume typically is about 1×10 −3  cc; however, flow controller volume can be any volume greater than zero which still allows for functionality as a flow controller. In some embodiments, flow controller volume is greater than 1×10 −2  cc. The upper limit for flow controller volume is the difference between the volume of molding compound in a certain package and the volume of stacked dies and die adhesive layers contained within the package. 
         [0028]    A disclosed method for manufacturing a semiconductor package comprises providing a substrate and a flow controller operatively associated with the substrate and effectively sized and positioned to control flow of a molding compound. Alternatively, plural flow controllers may be provided. During the encapsulation process molding compound flows over the surface of the flow controllers, dies, and substrate, as in the typical encapsulation process. In one embodiment, using flow controllers does not require altering the encapsulation process beyond application of the flow controllers themselves. 
         [0029]    Disclosed method for using flow controllers comprises providing a flow controller operable to influence or control flow of a molding compound. For example, flow controllers can reduce the speed of molding compound, direct its flow, and/or divert flow of a molding compound from certain areas of the semiconductor package. In some embodiments, flow controllers substantially create a uniform leading edge of molding compound flow and, as a result, reduce the occurrence of defects during encapsulation. Thus, flow controllers substantially can prevent internal and external voids, wire sweeping, and wire shorts, and can facilitate filling a narrow encapsulant gap. 
         [0030]    Semiconductor packages, generally such as fine ball grid array packages and polymer ball grid arrays, such as plastic ball grid arrays, may be manufactured according to the disclosed methods. Once encapsulation is complete, semiconductor packages with flow controller elements can be incorporated into any electronic product requiring IC assemblies. These include such devices as computers, personal digital assistants, digital cameras, and cellular telephones. Instructions for providing the disclosed flow controllers can be included on a computer readable medium. 
         [0031]    The foregoing and other objects, features, and advantages of the invention will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0032]      FIG. 1  is a cross-sectional view of a prior art ball grid array semiconductor package. 
           [0033]      FIG. 2  is a plan view illustrating one embodiment of a ball grid array semiconductor package with bonded wires and a plurality of flow controllers. 
           [0034]      FIG. 3  is a schematic plan view illustrating the leading edge of molding compound flowing over a device comprising a plurality of flow controllers. 
           [0035]      FIG. 4  is a cross sectional view of a single stack ball grid array semiconductor package comprising a flow controller. 
           [0036]      FIG. 5  is a plan view of blocked fine ball grid array semiconductor packages before encapsulation. 
           [0037]      FIG. 6  is a plan view of a single blocked fine ball grid array semiconductor package comprising a plurality of flow controllers. 
           [0038]      FIG. 7  is a plan view of a prior art ball grid array semiconductor package illustrating molding compound flow in the absence of flow controllers. 
           [0039]      FIG. 8  is a plan view of the single blocked ball grid array semiconductor package of  FIG. 6  illustrating molding compound flow using flow controllers according to one disclosed embodiment. 
           [0040]      FIG. 9  is a plan view of a plastic ball grid array semiconductor package comprising 4 units and a plurality of flow controllers illustrating flow of molding compound at various times during the encapsulation process. 
           [0041]      FIG. 10  is a cross sectional view of a ball grid array semiconductor package comprising a flow controller contacting bond wires and dies. 
           [0042]      FIG. 11  is a cross sectional view of a ball grid array semiconductor package comprising a flow controller located adjacent to bond wires and dies. 
           [0043]      FIG. 12  is a cross sectional view of the ball grid array semiconductor package of  FIG. 10  comprising flow controllers adjacent to saw lines. 
           [0044]      FIG. 13  is a cross sectional view of the ball grid array semiconductor package of  FIG. 11  comprising flow controllers adjacent to the lines. 
           [0045]      FIG. 14  is a cross sectional view of a ball grid array semiconductor package comprising flow controllers adjacent to bond wires and dies, where the illustrated embodiment of the flow controllers comprises a dummy block and an adhesive layer. 
           [0046]      FIG. 15  is a flowchart of one embodiment of a method for making a semiconductor package. 
           [0047]      FIG. 16  is a flowchart of one embodiment of a method for providing flow controllers during semiconductor package manufacture. 
           [0048]      FIG. 17  is a flowchart of an alternative embodiment of a method for providing flow controllers during semiconductor package manufacture. 
           [0049]      FIG. 18  is a flowchart of another alternative embodiment of a method for providing flow controllers during semiconductor package manufacture. 
           [0050]      FIG. 19  is a flowchart of another alternative embodiment of a method for providing flow controllers during semiconductor package manufacture. 
           [0051]      FIG. 20  is a flowchart of one embodiment of a method for directing molding compound flow. 
       
    
    
     TERMS 
       [0052]    As used in this application and in the claims, the singular forms “a,” “an,” and “the” include the plural forms unless the context clearly dictates otherwise. Additionally, the term “includes” means “comprises.” Further, the term “coupled” means physically, electrically and/or electromagnetically coupled or linked and does not exclude the presence of intermediate elements between the coupled items. 
         [0053]    Although the operations of embodiments of the disclosed method are described in a particular, sequential order for convenient presentation, it should be understood that this manner of description encompasses rearrangement, unless a particular ordering is required by specific language set forth below. For example, operations described sequentially may in some cases be rearranged or performed concurrently. Moreover, for the sake of simplicity, the attached figures may not show the various ways in which the disclosed system, method, and apparatus can be used in conjunction with other systems, methods, and apparatus. Additionally, the description sometimes uses terms like “produce” and “provide” to describe the disclosed method. These terms may be high-level abstractions of the actual operations that can be performed. The actual operations that correspond to these terms can vary depending on the particular implementation and are discernible by a person of ordinary skill in the art. 
       DETAILED DESCRIPTION 
       [0054]      FIG. 2  shows a plan view of a semiconductor package  200 , comprising a substrate  202  and a die  210  electrically coupled to substrate  202  by a plurality of conductive bond wires  218 .  FIG. 2  also illustrates various positions for flow controllers  220 ,  222 , and  224  relative to other package components. Each of these can be used alone, or any and all combinations of such positioning can be used. For example, one or more flow controllers  220  optionally can be positioned adjacent to, but substantially outside a perimeter defined by, bond wires  218 . Plural flow controllers  220 ,  222 , and  224  are illustrated in  FIG. 2 , however there may be more or fewer flow controllers in any given embodiment. 
         [0055]    In another embodiment, one or more flow controllers  222  optionally can be positioned substantially within the perimeter defined by bond wires  218 . Flow controller  222  can be coupled to substrate  202  and can be positioned between adjacent bond wires  218 , such that flow controller  222  does not contact bond wires  218 . Plural flow controllers  222  are illustrated in  FIG. 2 , however there may be more or fewer flow controllers  222  in any given embodiment. 
         [0056]    In still another embodiment, one or more flow controllers  222  can be positioned within the perimeter defined by bond wires  218 , and one or more flow controllers  220  may be positioned around the perimeter defined by bond wires  218 . In yet another embodiment, one or more flow controllers  224  may have a first portion located within the perimeter defined by bond wires  218 , and a second portion located outside the perimeter defined by bond wires  218 . As shown in  FIG. 2 , flow controllers  220 ,  222 , and  224  do not have to be positioned relative to one another to form gates. Instead, during encapsulation, molding compound (not shown) flows over and about flow controllers  220 ,  222 , and/or  224 . 
         [0057]      FIG. 2  illustrates various positions for flow controllers  220 ,  222 , and  224  for one embodiment. A person of ordinary skill in the art will recognize that in any given embodiment, some or all of these positions may be used, alone or in combination. For example, flow controllers  220 ,  222 , and/or  224  can be positioned to protect a specific wire  218  or a group of such wires  218  from damage. Flow controllers  220 ,  222 , and/or  224  also can divert molding compound flow from a specific area on substrate  202 . 
         [0058]    Substrate  202  can comprise any material commonly used in the semiconductor industry. These include, but are not limited to, flexible resin tape, fiberglass/copper sheet laminate, ceramic, flexible metal lead frame, and ball grid arrays. Substrate  202  is not limited to semiconductor materials; it can be formed of semiconducting materials, insulating materials, conducting materials, or combinations thereof. Substrate  202  optionally can include thermal vias, or holes, extending from a first surface to a second surface, to allow heat to escape. 
         [0059]    Die  210  usually comprises semiconductor materials, such as silicon, germanium, or gallium arsenide. Each die can comprise multiple semiconductor devices, often in layers, such as can be formed via photolithographic techniques. Dies  210  are typically active components, in that they usually require a power supply to operate. Passive components are those which do not need a power supply to function, and include components such as resistors, capacitors, and inductors. In addition to one or more dies  210 , substrate  202  optionally may include one or more passive components. 
         [0060]      FIG. 3  shows a plan view of semiconductor device  300  comprising substrate  302  and a plurality of dies  310 , each which can be identical or distinct, and each with a plurality of bond wires  318  electrically coupling dies  310  to substrate  302 .  FIG. 3  also illustrates a plurality of flow controllers  320  interspersed between dies  310 . Leading edges  326 ,  328 , and  330  of molding compound flow represent three different points in time as molding compound flows from left to right along device  300 . Leading edge  326  depicts the flow profile at a first time substantially at the beginning of the encapsulation process, while leading edge  328  is at a second time near the middle of the process, and leading edge  330  depicts the flow profile at a third time nearing completion of encapsulation. Flow controllers  320  can facilitate molding compound flow, such as to keep leading edge  326  substantially similar to leading edges  328  and  330 . The more smoothly molding compound flows, the less likely defects are to develop. Thus, flow controllers  320  substantially can prevent defects from forming in the encapsulated device. In this as well as all other embodiments, variable features of flow controllers  320 , such as volume, surface area, shape, and location, can be optimized based on the structure of semiconductor package  300  or dies  310  or based on the desired effect on molding compound flow. 
         [0061]      FIG. 4  shows a cross sectional view taken along line  4 - 4  in  FIG. 3 . A single die  404  is physically attached to substrate  402  by die adhesive layer  403 , and electrically coupled to substrate  402  via bond wires  418 . Flow controller  420  is shown coupled to substrate  402 , and adjacent to die  404  and bond wires  418 . In the illustrated embodiment of  FIG. 4 , the heights of flow controller  420  and die  404  are substantially similar. However, in other embodiments, flow controller  420  heights can be selected for a particular purpose. As a result, in other embodiments, there is no particular height required for flow controller  420 , nor does its height have to be substantially similar to the height of die  404 . The embodiment shown in  FIG. 4  optionally can include additional dies  404  and adhesive layers  403 , which may comprise devices identical to or different from die  404 . 
         [0062]      FIG. 5  shows a plan view of semiconductor package  500  before encapsulation, comprising substrate  502 , and a plurality of dies  506 ,  508 , and  510  arrayed on substrate  502 . Dies  506 ,  508 , and  510  are stacked and arranged into four blocks  511 . As shown in  FIG. 5 , each die stack comprises die  506  adhered to substrate  502 , die  508  adhered to die  506 , and die  510  adhered to die  508 . As one skilled in the art will recognize, dies  506 ,  508 , and  510  may be identical or distinct devices. Dies  506 ,  508 , and  510  are not limited in any way by their depiction in  FIG. 5 ; there may be additional dies stacked amongst dies  506 ,  508 , and  510 . Further, as shown in  FIG. 5 , die  510  has a smaller footprint than die  508 , which in turn has a smaller footprint than die  506 .  FIG. 5  illustrates only one embodiment of possible arrangements of dies. In other embodiments, die  510  may have a larger or smaller footprint than die  508 , which may have a larger or smaller footprint than die  506  or any other dies present in the stack. 
         [0063]    Package  500  further comprises a plurality of flow controllers  520  interspersed between stacked dies  506 ,  508 , and  510 . In this embodiment, flow controllers  520  are located inside a perimeter defined by each block  511 , adjacent to dies  506 ,  508 , and  510 . In alternative embodiments, flow controllers  520  optionally can be positioned at various other locations, such as in areas of substrate  502  between blocks  511 , or adjacent to some dies  506 ,  508 , and  510 , but not others. 
         [0064]      FIG. 6  shows a plan view of semiconductor package  600  comprising substrate  602 , and a plurality of dies  606 ,  608 , and  610  stacked and arrayed on substrate  602 . As shown in  FIG. 6 , each die stack comprises die  606  adhered to substrate  602 , die  608  adhered to die  606 , and die  610  adhered to die  608 . As a person of ordinary skill in the art will recognize, dies  606 ,  608 , and  610  may be identical or distinct devices. Dies  606 ,  608 , and  610  are not limited in any way by their depiction in  FIG. 6 ; there may be additional dies stacked amongst dies  606 ,  608 , and  610 . Further, as shown in  FIG. 6 , die  610  has a smaller footprint than die  608 , which in turn has a smaller footprint than die  606 .  FIG. 6  illustrates only one embodiment of possible arrangements of dies. In other embodiments, die  610  may have a larger or smaller footprint than die  608 , which may have a larger or smaller footprint than die  606  or any other dies present in the stack. 
         [0065]    Package  600  further comprises a plurality of flow controllers  620  interspersed between die stacks.  FIG. 6  illustrates a certain placement of flow controllers  620 . A person of ordinary skill in the art will recognize that the scope of possible embodiments is not limited to the illustrated positioning. For example, flow controllers  620  can be positioned outside a perimeter defined by arrayed dies  606 ,  608  and  610 . Alternatively, flow controllers  620  can be positioned between some dies  606 ,  608 , and  610 , but not others. Positioning of flow controllers  620  can be altered to affect molding compound flow as desired. 
         [0066]      FIG. 7  shows a plan view of a prior art semiconductor package  700  comprising substrate  702 , and a plurality of dies  706 ,  708 , and  710  stacked and arrayed on substrate  702 . As shown in  FIG. 7 , each die stack comprises die  706  adhered to substrate  702 , die  708  adhered to die  706 , and die  710  adhered to die  708 . A person of ordinary skill in the art will recognize that dies  706 ,  708 , and  710  may be identical or distinct devices. Dies  706 ,  708 , and  710  are not limited in any way by their depiction in  FIG. 7 ; there may be additional dies stacked amongst dies  706 ,  708 , and  710 . Further, as shown in  FIG. 7 , die  710  has a smaller footprint than die  708 , which in turn has a smaller footprint than die  706 .  FIG. 7  illustrates only one embodiment of possible arrangements of dies. In other embodiments, die  710  may have a larger or smaller footprint than die  708 , which may have a larger or smaller footprint than die  706  or any other dies present in the stack. 
         [0067]    Package  700  further comprises molding compound  714 , shown during an encapsulation process. In this illustrated embodiment, molding compound  714  flows in a direction from first edge  715  to second edge  717 . For clarity, molding compound  714  is only shown over a portion of package  700 . A first leading edge  726  of molding compound  714  is shown at a point almost half way through the encapsulation process. A second leading edge  728  is shown at a point nearing the end of the encapsulation process. Flow of molding compound  714  is uneven and results in defect formation, such as in area  732 . Some dies  706 ,  708 , and/or  710  near second edge  717  may not be encapsulated, or may not be fully encapsulated, due to areas  732 . 
         [0068]    For comparison,  FIG. 8  is a plan view of semiconductor package  800  according to one embodiment of the present invention, comprising substrate  802  and a plurality of dies  806 ,  808 , and  810  stacked and arrayed on substrate  802 , where dies  806 ,  808 , and  810  are partially obscured by molding compound  814 . As shown in  FIG. 8 , each die stack comprises die  806  adhered to substrate  802 , die  808  adhered to die  806 , and die  810  adhered to die  808 . A person of ordinary skill in the art will recognize that dies  806 ,  808 , and  810  may be identical or distinct devices. Dies  806 ,  808 , and  810  are not limited in any way by their depiction in  FIG. 8 ; there may be additional dies stacked amongst dies  806 ,  808 , and  810 . Further, as shown in  FIG. 8 , die  810  has a smaller footprint than die  808 , which in turn has a smaller footprint than die  806 .  FIG. 8  illustrates only one embodiment of possible arrangements of dies. In other embodiments, die  810  may have a larger or smaller footprint than die  808 , which may have a larger or smaller footprint than die  806  or any other dies present in the stack. 
         [0069]    Package  800  further comprises a plurality of flow controllers  820  interspersed between stacked dies  806 ,  808 , and  810 . As in  FIG. 7 , encapsulation is in progress, as indicated by molding compound  814  flowing in a direction from first edge  815  to second edge  817 . For clarity, molding compound  814  is only shown over a portion of package  800 . A first leading edge  826  of molding compound  814  is shown at a point almost half way through the encapsulation process. A second leading edge  828  is shown at a point nearing the end of encapsulation. However, in this embodiment, flow controllers  820  have resulted in more uniform first and second leading edges  826  and  828  of molding compound  814 , when compared with leading edges  726  and  728  in  FIG. 7 . As a result, some embodiments of the present invention can substantially reduce flow defects. For example, dies  806 ,  808 , and  810  will not be left exposed, and/or there will be a reduction in exposure after the encapsulation process is complete. Moreover, at this stage in encapsulation, exposed areas  832  are much smaller than exposed areas  732  in  FIG. 7 , and thus, formation of air pockets is less likely. Flow controllers  820  thus can substantially reduce, and potentially eliminate, the presence of defects such as voids, wire sweeping, and wire shorts, which can form during encapsulation. 
         [0070]      FIG. 9  shows a plan view of semiconductor package  900  during encapsulation. Package  900  comprises substrate  902 , a row of four dies  910 , a plurality of bonding wires  918  electrically coupling dies  910  to substrate  902 , and one or more flow controllers  922 . Package  900  further comprises a molding compound  914  flowing in a diagonal direction across package  900  from a first corner  915  to a second corner  917 . For clarity, molding compound  914  is only shown over a portion of package  900 . A first leading edge  926  of molding compound  914  is shown at a point about a quarter of the way through encapsulation. A second leading edge  928  is shown at a point about half way through encapsulation. Flow controllers  922  provide for substantially smooth leading edges  926  and  928 . In this embodiment, flow controllers  922  are located substantially within a perimeter defined by bond wires  918 . In other embodiments, flow controllers  922  can be positioned elsewhere, such as outside a perimeter defined by bond wires  918 , or partly within and partly outside the perimeter defined by bond wires  918 . 
         [0071]      FIG. 10  shows a cross sectional view of one possible embodiment, comprising substrate  1002  supporting dies  1004 ,  1006  and  1008 , which are adhered via die adhesive layers  1003 ,  1005 , and  1007 . Adhesive layer  1003  couples die  1004  to substrate  1002 , adhesive layer  1005  couples die  1006  to die  1004 , and adhesive layer  1007  couples die  1008  to die  1006 . Dies  1004 ,  1006 , and  1008  may be identical or distinct devices. Dies  1004 ,  1006 , and  1008  are not limited in any way by their depiction in  FIG. 10 ; there may be additional dies stacked amongst dies  1004 ,  1006 , and  1008 . Further, as shown in  FIG. 10 , die  1008  has a smaller footprint than die  1006 , which in turn has a smaller footprint than die  1004 .  FIG. 10  illustrates only one embodiment of possible die arrangement. In other embodiments, die  1008  may have a larger or smaller footprint than die  1006 , which may have a larger or smaller footprint than die  1004  or any other dies present in the stack. 
         [0072]    Dies  1004 ,  1006 , and  1008  are electrically coupled to substrate  1002  by a plurality of bonding wires  1018 . This embodiment further comprises a layer of flow controller material  1020  and encapsulant  1014 . Flow controller  1020  can be applied such that it contacts substrate  1002 , dies  1004 ,  1006 , and  1008 , and bonding wires  1018 , as shown in  FIG. 10 . In this embodiment, flow controller  1020  substantially can contact all exposed surfaces within the semiconductor package, including the surfaces of substrate  1002 , dies  1004 ,  1006 , and  1008 , bond wires  1018 , and any passive devices present. Flow controller  1020  can contact substantially the entire length of at least one bond wire  1018  such that bond wire  1018  is substantially embedded within flow controller  1020 . Further,  FIG. 10  optionally can include a saw line  1240 , as in  FIG. 12 . The embodiment illustrated in  FIG. 10  comprises bond wires  1018 ; however, in alternative embodiments, dies  1004 ,  1006 , and  1008  can be electrically coupled to substrate  1002  without bond wires  1018 . In this alternative embodiment, flow controllers  1020  can remain in contact with dies  1004 ,  1006 , and  1008  as well as substrate  1002 . 
         [0073]      FIG. 11  shows a cross sectional view of an another alternative embodiment, comprising substrate  1102  and dies  1104 ,  1106 , and  1108  adhered to substrate  1102  via adhesive layers  1103 ,  1105 , and  1107 , and electrically coupled to substrate  1102  by a plurality of bond wires  1118 . Adhesive layer  1103  couples die  1104  to substrate  1102 , adhesive layer  1105  couples die  1106  to die  1104 , and adhesive layer  1107  couples die  1108  to die  1106 . Dies  1104 ,  1106 , and  1108  may be identical or distinct devices. Dies  1104 ,  1106 , and  1108  are not limited in any way by their depiction in  FIG. 11 ; there may be additional dies stacked amongst dies  1104 ,  1106 , and  1108 . Further, as shown in  FIG. 11 , die  1108  has a smaller footprint than die  1106 , which in turn has a smaller footprint than die  1104 .  FIG. 11  illustrates only one embodiment of possible die arrangement. In other embodiments, die  1108  may have a larger or smaller footprint than die  1106 , which may have a larger or smaller footprint than die  1104  or any other dies present in the stack. 
         [0074]    The embodiment illustrated in  FIG. 11  further comprises an encapsulant  1114  and one or more flow controllers  1120  positioned adjacent to bond wires  1118 . In this embodiment, and in contrast to  FIG. 10 , flow controllers  1120  contact neither dies  1104 ,  1106 , and  1108  nor bond wires  1118 . Flow controllers  1120  are coupled to substrate  1102 , but do not pass under or around bond wires  1118 . In the illustrated embodiment of  FIG. 11 , the heights of flow controller  1120  and stacked dies  1104 ,  1106  and  1108  are substantially similar. However, in other embodiments, flow controller  1120  heights can be selected for a particular purpose. As a result, in other embodiments, there is no particular height required for flow controller  1120 , nor does its height need be substantially similar to the height of stacked dies  1104 ,  1106 , and  1108 . Further, the embodiment illustrated in  FIG. 11  optionally can include a saw line  1340 , as in  FIG. 13 . 
         [0075]      FIG. 12  shows a cross sectional view of semiconductor package  1200 , comprising substrate  1202  supporting a first stack of dies  1204 ,  1206  and  1208  adhered via adhesive layers  1203 ,  1205 , and  1207 , and a second stack of dies  1234 ,  1236 , and  1238  adhered via die adhesive layers  1233 ,  1235 , and  1237 . Adhesive layer  1203  couples die  1204  to substrate  1202 , adhesive layer  1205  couples die  1206  to die  1204 , adhesive layer  1207  couples die  1208  to die  1206 , adhesive layer  1233  couples die  1234  to substrate  1202 , adhesive layer  1235  couples die  1236  to die  1234 , and adhesive layer  1237  couples die  1238  to die  1236 . Dies  1204 ,  1206 ,  1208 ,  1234 ,  1236 , and  1238  may be identical or distinct devices. Dies  1204 ,  1206 ,  1208 ,  1234 ,  1236 , and  1238  are not limited in any way by their depiction in  FIG. 12 ; there may be additional dies stacked amongst shown dies  1204 ,  1206 ,  1208 ,  1234 ,  1236 , and  1238 . Further, as shown in  FIG. 12 , die  1208  has a smaller footprint than die  1206 , which in turn has a smaller footprint than die  1204 , while 1238 has a smaller footprint than die  1236 , which in turn has a smaller footprint than die  1234 .  FIG. 12  illustrates only one embodiment of possible die arrangement. In other embodiments, die  1208  may have a larger or smaller footprint than die  1206 , which may have a larger or smaller footprint than die  1204  or any other dies present in the stack. Similarly, die  1238  may have a larger or smaller footprint than die  1236 , which may have a larger or smaller footprint than die  1234  or any other die present in the stack. 
         [0076]    Dies  1204 ,  1206 ,  1208 ,  1234 ,  1236 , and  1238  are electrically coupled to substrate  1202  by a plurality of bond wires  1218 . This embodiment further comprises encapsulant  1214 , first flow controller  1220   a  and second flow controller  1220   b . Package  1200  is designed for singulation along saw line  1240  to produce a plurality of individual packages. Saw line  1240  separates first flow controller  1220   a  from second flow controller  1220   b . First flow controller  1220   a  can be identical to second flow controller  1220   b . Alternatively, first flow controller  1220   a  can differ from second flow controller  1220   b  in size, shape, and/or composition. Additionally,  FIG. 12  may represent the cross section of only a portion of an entire semiconductor package. Alternative embodiments may comprise multiple other die stacks, similar to dies  1204 ,  1206 ,  1208 ,  1234 ,  1236 , and  1238 , as well as a plurality of other flow controllers, similar to flow controllers  1220   a  and  1220   b.    
         [0077]    Flow controllers  1220   a  and/or  1220   b  can be positioned such that they contact substrate  1202 , dies  1204 ,  1206 ,  1208 ,  1234 ,  1236 , and  1238  and bonding wires  1218 , as shown in  FIG. 12 . In this embodiment, flow controllers  1220   a  and  1220   b  substantially can contact all exposed surfaces within the semiconductor package, including the surfaces of substrate  1202 , dies  1204 ,  1206 ,  1208 ,  1234 ,  1236 , and  1238 , bond wires  1218 , and any passive devices present. Flow controllers  1220   a  and/or  1220   b  can contact substantially the entire length of at least one bond wire  1218  such that bond wire  1218  is substantially embedded within flow controllers  1220   a  and  1220   b . In this embodiment, flow controllers  1220   a  and  1220   b  do not extend to cover the entire distance between first stacked dies  1204 ,  1206 , and  1208  and second stacked dies  1234 ,  1236 , and  1238  because there is an interruption between flow controllers  1220   a  and  1220   b  along saw line  1240 . Flow controllers  1220   a  and  1220   b  are adjacent to saw line  1240 , but do not extend across it. In this embodiment, flow controllers  1220   a  and  1220   b  will not be visible after singulation, because encapsulant  1214  fills the space between flow controller  1220   a  and flow controller  1220   b.    
         [0078]    The embodiment of  FIG. 12  comprises bond wires  1218 ; however, in alternative embodiments, dies  1204 ,  1206 ,  1208 ,  1234 ,  1236 , and  1238  can be electrically coupled to substrate  1202  without bond wires  1218 . In this alternative embodiment, flow controllers  1220   a  and  1220   b  can remain in contact with dies  1204 ,  1206 ,  1208 ,  1234 ,  1236 , and  1238  as well as substrate  1202 . 
         [0079]      FIG. 13  shows a cross sectional view of semiconductor package  1300  comprising substrate  1302  supporting a first stack of dies  1304 ,  1306  and  1308  adhered via adhesive layers  1303 ,  1305 , and  1307 , and a second stack of dies  1334 ,  1336 , and  1338  adhered via adhesive layers  1333 ,  1335 , and  1337 . Adhesive layer  1303  couples die  1304  to substrate  1302 , adhesive layer  1305  couples die  1306  to die  1304 , adhesive layer  1307  couples die  1308  to die  1306 , adhesive layer  1333  couples die  1334  to substrate  1302 , adhesive layer  1335  couples die  1336  to die  1334 , and adhesive layer  1337  couples die  1338  to die  1336 . Dies  1304 ,  1306 ,  1308 ,  1334 ,  1336 , and  1338  may be identical or distinct devices. Dies  1304 ,  1306 ,  1308 ,  1334 ,  1336 , and  1338  are not limited in any way by their depiction in  FIG. 13 ; there may be additional dies stacked amongst shown dies  1304 ,  1306 ,  1308 ,  1334 ,  1336 , and  1338 . Further, as shown in  FIG. 13 , die  1308  has a smaller footprint than die  1306 , which in turn has a smaller footprint than die  1304 , while 1338 has a smaller footprint than die  1336 , which in turn has a smaller footprint than die  1334 .  FIG. 13  illustrates only one embodiment of possible die arrangement. In other embodiments, die  1308  may have a larger or smaller footprint than die  1306 , which may have a larger or smaller footprint than die  1304  or any other dies present in the stack. Similarly, die  1338  may have a larger or smaller footprint than die  1336 , which may have a larger or smaller footprint than die  1334  or any other dies present in the stack. 
         [0080]    Dies  1304 ,  1306 ,  1308 ,  1334 ,  1336 , and  1338  are electrically coupled to substrate  1302  by a plurality of bond wires  1318 . This embodiment further comprises an encapsulant  1314 , first flow controller  1320   a  and second flow controller  1320   b . Package  1300  subsequently will be singulated along saw line  1340  to produce a plurality of individual packages. Saw line  1340  separates first flow controller  1320   a  from second flow controller  1320   b . First flow controller  1320   a  can be identical to second flow controller  1320   b . Alternatively, first flow controller  1320   a  can differ from second flow controller  1320   b  in size, shape, and/or composition. Additionally,  FIG. 13  may represent the cross section of only a portion of an entire semiconductor package. Alternative embodiments may comprise multiple other die stacks, similar to dies  1304 ,  1306 ,  1308 ,  1334 ,  1336 , and  1338 , as well as a plurality of other flow controllers, similar to flow controllers  1320   a  and  1320   b.    
         [0081]    Flow controllers  1320   a  and/or  1320   b  can be positioned such that they contact neither dies  1304 ,  1306 ,  1308 ,  1334 ,  1336 , and  1338  nor bond wires  1318  as shown in  FIG. 13 . Flow controllers  1320   a  and  1320   b  are coupled to substrate  1302 , but do not pass under or around bond wires  1318 . In this embodiment, flow controllers  1320   a  and  1320   b  do not extend to cover the entire distance between first stack of dies  1304 ,  1306 , and  1308  and second stack of dies  1334 ,  1336 , and  1338  because there is an interruption between flow controllers  1320   a  and  1320   b  along saw line  1340 . Flow controllers  1320   a  and  1320   b  are adjacent to saw line  1340 , but do not extend across it. In this embodiment, flow controllers  1320   a  and  1320   b  will not be visible after singulation, because encapsulant  1314  fills the space between flow controller  1320   a  and flow controller  1320   b.    
         [0082]    The embodiment illustrated in  FIG. 13  comprises bond wires  1318 ; however, in alternative embodiments, dies  1304 ,  1306 ,  1308 ,  1334 ,  1336 , and  1338  can be electrically coupled to substrate  1302  without bond wires  1318 . In this embodiment, flow controllers  1320   a  and  1320   b  can remain coupled to substrate  1302  without contacting dies  1304 ,  1306 ,  1308 ,  1334 ,  1336 , or  1338 . 
         [0083]    In a further embodiment, illustrated in cross section by  FIG. 14 , package  1400  comprises substrate  1402  and dies  1404 ,  1406 , and  1408  adhered to substrate  1402  via adhesive layers  1403 ,  1405 , and  1407 . Adhesive layer  1403  couples die  1404  to substrate  1402 , adhesive layer  1405  couples die  1406  to die  1404 , and adhesive layer  1407  couples die  1408  to die  1406 . Dies  1404 ,  1406 , and  1408  may be identical or distinct devices. Dies  1404 ,  1406 , and  1408  are not limited in any way by their depiction in  FIG. 14 ; there may be additional dies stacked amongst dies  1404 ,  1406 , and  1408 . Further, as shown in  FIG. 14 , die  1408  has a smaller footprint than die  1406 , which in turn has a smaller footprint than die  1404 .  FIG. 14  illustrates only one embodiment of possible die arrangement. In other embodiments, die  1408  may have a larger or smaller footprint than die  1406 , which may have a larger or smaller footprint than die  1404  or any other dies present in the stack. 
         [0084]    This embodiment further comprises a plurality of bond wires  1418  electrically coupling dies  1404 ,  1406 , and  1408  to substrate  1402 , an encapsulant  1414 , and one or more dummy blocks  1444  adhered to substrate  1402  via adhesive layer  1442 . Dummy blocks  1444  are referred to as such because they require an adhesive layer  1442 . Dummy blocks  1444  can be composed of a polymeric material or other materials commonly used in the semiconductor industry. The combination of dummy block  1444  and adhesive layer  1442  can control flow of molding compound  1414  during encapsulation, and thus can function as a flow controller. Alternatively, dummy block  1444  can be coupled to yet another material, which would perform flow controlling functions. The embodiment of  FIG. 14  shows a single-layer dummy block  1444  coupled to adhesive layer  1442 . Alternative embodiments can comprise a plurality of dummy block layers coupled to adhesive layer  1442 . For example, the scope of possible embodiments encompasses the use of adhesive layer  1442  coupled to an interposer, which is in turn coupled to dummy block  1444 , which is in turn coupled to a separate flow controller material. Additional layers can be added, or layers may be removed in various embodiments. The order of layers presented is not restrictive. 
         [0085]    Dummy blocks  1444  are positioned adjacent to bond wires  1418 , such that dummy blocks  1444  contact neither dies  1404 ,  1406 , and  1408  nor bond wires  1418 . Dummy blocks  1444  are coupled to substrate  1402 , but do not pass under or around bond wires  1418 . Adhesive layer  1442  may be applied adjacent to bond wires  1418  as illustrated in  FIG. 14 . Alternatively, adhesive layer  1442  may be applied so that i 
         [0086]    contacts substrate  1402 , dies  1404 ,  1406 , and  1408 , as well as bond wires  1418 . In this alternative embodiment, dummy block  1444  may still be positioned so that it does not contact dies  1404 ,  1406 , and  1408 , or bond wires  1418 . 
         [0087]    As seen in  FIG. 14 , the heights of dummy block  1444  and stacked dies  1404 ,  1406  and  1408  are substantially similar. However, in other embodiments, dummy block  1444  height can be selected for a particular purpose. As a result, in other embodiments, there is no particular height required for dummy block  1444 , nor does its height need be substantially similar to the height of stacked dies  1404 ,  1406 , and  1408 . Further,  FIG. 14  optionally can include a saw line such as saw line  1340 , of  FIG. 13 . 
         [0088]      FIG. 15  is a flowchart of one embodiment of a method for making a semiconductor package. One or more flow controllers can be positioned for association with a substrate optionally having at least one die electrically coupled thereto (step  1500 ). Flow controller volume, height, surface area, and/or shape can be selected to achieve the desired effect on molding compound flow. Flow controllers are made using any suitable material, including by way of example and without limitation, die adhesive, die coating material, polymeric material, screen printing material, solder paste, or combinations thereof. Flow controllers can comprise a non-insulating material. Positioning of flow controllers can be accomplished via epoxy dispensing and attach systems, epoxy dotting and attach systems, die coating, screen printing, or combinations thereof. 
         [0089]    A molding compound is flowed over the surface of the substrate and flow controllers (step  1502 ). In some embodiments, flow controllers control molding compound flow, in order to provide a more uniform leading edge. Flow controllers also can decrease the flow rate relative to a package devoid of a flow controller or controllers. Once the semiconductor package has been encapsulated by molding compound, it can be incorporated into various electronic products (step  1504 ). A person of ordinary skill in the art will recognize that the order of steps as presented in  FIG. 15  is not strictly limited to that order, and that other embodiments may reorder method steps. 
         [0090]      FIG. 16  is a flowchart of one embodiment of a method for providing flow controllers during semiconductor package manufacture. A substrate can be provided (step  1600 ), and one or more dies can be attached or otherwise effectively coupled to the substrate (step  1602 ). Afterwards, one or more flow controllers can be provided (step  1604 ) and can be positioned as desired relative to other package components, such as the die or dies. 
         [0091]    Alternatively,  FIG. 17  is a flowchart of another embodiment of a method for using flow controllers for semiconductor package manufacture. A substrate can be provided (step  1700 ), and one or more flow controllers can be provided (step  1702 ) and attached or otherwise effectively coupled to the substrate before die attachment (step  1704 ). 
         [0092]      FIG. 18  is a flowchart of yet another embodiment of a method for using flow controllers to manufacture a semiconductor package. A substrate can be provided with one or more dies (step  1800 ). Wire bonding can be performed (step  1802 ) to electrically couple the dies to the substrate, followed by positioning of one or more flow controllers (step  1804 ). 
         [0093]    Alternatively,  FIG. 19  is a flowchart of another embodiment of a method for using flow controllers to manufacture a semiconductor package. A substrate can be provided with one or more dies (step  1900 ). Flow controllers can be provided (step  1902 ) before wire bonding (step  1904 ) occurs. 
         [0094]      FIG. 20  is a flowchart of one embodiment of a method for controlling molding compound flow. A molding compound can be provided (step  2000 ). Flow controllers can be positioned to direct molding compound flow in desired directions (step  2002 ). In another embodiment, a substrate can be provided (step  2004 ), and flow can be diverted away from certain areas of the substrate via flow controller placement (step  2006 ). A person of ordinary skill in the art will recognize that the order of steps as presented in  FIG. 20  is not strictly limited to that order, and that other embodiments may reorder method steps. 
         [0095]    In view of the many possible embodiments to which the principles of the disclosed invention may be applied, it should be recognized that the illustrated embodiments are only preferred examples of the invention and should not be taken as limiting the scope of the invention. Rather, the scope of the invention is defined by the following claims. We therefore claim as our invention all that comes within the scope and spirit of these claims.