Abstract:
An integrated circuit package with improved reliability and methods for creating the same are disclosed. More specifically, integrated circuit packages are created using one or more sacrificial layers that provide support for ink printed wires prior to package processing, but are removed during package processing. Once each of the sacrificial layers is removed, molding compound is placed around each ink printed wire, which may have a substantially rectangular cross section that can vary in dimension along a length of a given wire. While substantially surrounding each wire in and of itself improves reliability, removing non-conductive paste, fillets, or other adhesive materials also minimizes adhesion issues between the molding compound and those materials, which increases the bond of the molding compound to the package and its components. The net result is a more reliable integrated circuit package that is less susceptible to internal cracking and wire damage.

Description:
BACKGROUND 
     Technical Field 
     The present disclosure is directed to ink printing of wires in integrated circuit packages using a sacrificial layer for ink wire support that is removed during integrated circuit package processing. 
     Description of the Related Art 
     Various ink printing techniques exist to form wires in packaging. One example is, aerosol ink printing, which uses aerodynamic focusing to precisely and accurately deposit electronic inks onto a substrate. More specifically, liquid ink containing solid particles is placed in a sealed jar or chamber and atomized to create an aerosol of ink droplets with entrained particles. Then, the aerosol is condensed as it moves to a deposition head, where a sheath gas “focuses” the dense aerosol mist into a tight stream of particle laden droplets flowing inside the sheath gas. This stream can then be directed to a surface of a substrate to deposit the focused mist on the substrate. Aerosol ink printing devices can be driven by standard CAD data that is converted to make a vector based tool path for a motion control system, which allows for precise control in depositing such inks. 
     One specific application of aerosol ink printing is for creating interconnects between layers or die, of an integrated circuit package, with some systems using an ink containing metal particles and multiple deposition heads to print up to 25,000 or more interconnects per hour. However, according to these methods and devices, a glue or non-conductive paste (“NCP”) fillet supports the aerosol ink printed wires in the integrated circuit package. This glue or NCP occupies gaps between layers, or in other words, is placed between successive edges of one or more die, such that a typical aerosol ink printed wire would be printed over an edge of a first die, then over the glue or NCP fillet between layers, before being printed over an edge of a second die, and so on, until the wires are printed down to a connection on a surface of a printed circuit board (“PCB”) or other surface-mount device (“SMD”). Once the wires are printed, a molding compound is then placed over the SMD, the NPC and the wires to form the final integrated circuit package. 
     While technologies like aerosol ink printing allow for smaller integrated packages to be created, the expansion of trapped moisture and other issues in progressively smaller packages can lead to progressively larger problems, especially concerning reliability of the finished package. For example, trapped moisture in the package can result in internal separation, or delamination, of the wires from the die, of the molding compound from the NCP or of the molding compound from the wires. This delamination can lead to further problems, such as wire damage, die damage, and internal cracks in any part of the package. 
     In typical applications of aerosol ink printing, these problems arise due to the adhesion of the molding compound to the fillet, which is typically poor. However, there are also issues with wires having bends, or angles, along the length of the wire, because the bend or angle acts as a weak point compared to other sections of the wire. Therefore, a uniform force applied to the wire, possibly as a result of expanding moisture, leaves the bends or angles with a higher likelihood of cracking or breaking. In addition, the molding compound cannot fully surround and protect the wires, as the NCP fillet remains under the wire in the final packages. As a result, the poor adhesion and coverage of the molding compound within the integrated circuit package allows for expanding moisture to more easily separate components in the system, with the overall effect being a less reliable package. 
     BRIEF SUMMARY 
     The embodiments described in the present disclosure are directed to improving reliability of integrated circuit packages by using printed wires on one or more sacrificial layers that evaporate or are otherwise removed during package processing. After each of the sacrificial layers evaporate, molding compound can be placed on all sides of each ink printed wire, which increases support for each wire compared to glues or NCP fillets that remain under ink printed wires after package processing. In some variations, each of the ink printed wires may have a substantially rectangular cross section that can change in width, height, or a combination thereof, along a length of the ink printed wire. Other possibilities also include printing wires with different compositions in the same integrated circuit package. 
     Other exemplary embodiments of the present disclosure describe methods for creating such integrated circuit packages. Some of those embodiments include attaching a die to a substrate and printing a plurality of wires over a surface of a sacrificial layer between pillars or bumps on the die and contact pads on the substrate. Then, a molding compound can be placed over the substrate, the die, and the plurality of wires with the molding compound substantially surrounding a portion of each wire. In yet other embodiments, the pillars or bumps have different heights and more than one sacrificial layer and more than one plurality of wires is used to connect the pillars or bumps of different heights to the contact pads. 
     A second exemplary method of the present disclosure shows that the present disclosure is not limited to use with a single die. Rather, the present disclosure provides the flexibility to use multiple die, multiple sacrificial layers and pillars with different heights on each die, among other combinations. For example, two die, each having pillars with a different height may be used with two sacrificial layers and multiple pluralities of wires to connect the pillars either to each other or to contact pads positioned successively further away from the die. Then, a molding compound is placed over the substrate, the die and the plurality of wires to form the final integrated circuit package with the molding compound substantially surrounding a portion of each wire. In this way, embodiments of the present disclosure allow for more connections to be made within an integrated circuit package, while also increasing the reliability of the package as a whole. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       In the drawings, identical reference numbers identify similar elements. The sizes and relative positions of elements in the drawings are not necessarily drawn to scale. 
         FIG. 1  is an isometric view of an exemplary embodiment of an integrated circuit package according to the present disclosure having one or more ink printed wires coupled between a substrate and two die; 
         FIGS. 2A-B  are views of an alternative exemplary embodiment of the integrated circuit package according to the present disclosure; 
         FIGS. 3A-F  are views of an exemplary method according to the present disclosure for creating an integrated circuit package using a first sacrificial layer and one or more ink printed wires with a die; 
         FIGS. 4A-E  are views of an alternative exemplary embodiment of the present disclosure including a printed wire and a secondary wire; 
         FIGS. 5A-C  are views of an alternative exemplary embodiment of the present disclosure having multiple sacrificial layers and pillars of different heights on one die; 
         FIGS. 6A-D  are views of an exemplary device according to the present disclosure for creating an integrated circuit package using multiple sacrificial layers and multiple pluralities of ink printed wires connecting two or more die to a substrate; 
         FIGS. 7A-D  are views of an alternative exemplary embodiment of the of the present disclosure having two die, printed wires, and secondary wires; 
         FIGS. 8A-C  are views of an alternative exemplary embodiment of the present disclosure having multiple pillar heights on different die; and 
         FIG. 9  is a top down view of a wire with varying dimensions. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, certain specific details are set forth in order to provide a thorough understanding of various embodiments of the disclosure. However, one skilled in the art will understand that the disclosure may be practiced without these specific details. In some instances, well-known details associated with chip packaging have not been described to avoid obscuring the descriptions of the embodiments of the present disclosure. 
     Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. 
     In the drawings, identical reference numbers identify similar features or elements. The size and relative positions of features in the drawings are not necessarily drawn to scale. 
     The present disclosure is directed to improving reliability of ink printed wires in integrated circuit packages.  FIG. 1  is an embodiment of the present disclosure with an integrated circuit package  100  having a package substrate  102 , where an encapsulant is not shown to illustrate an arrangement of a first die  103  and a second die  104  with ink printed wires  108 . The final product that includes this package will include a molding compound or the encapsulant that fully surrounds each of the ink printed wires and covers the die. The encapsulant will be described and illustrated below. 
     The package  100  includes a plurality of the ink printed wires  108  that are formed in conjunction with embodiments of the present disclosure where a sacrificial material was used during a manufacturing process to support the ink printed wires. The sacrificial material does not remain in the final product. The package  100  includes the first die  103  and the second die  104  stacked on the first die  103  on the package substrate  102 . 
     The package substrate  102  is of the type FR4 (organic substrate) with a substantially rectangular shape, although other embodiments may have different compositions or shapes depending on the application for the integrated circuit package  100 . The package substrate  102  includes a plurality of contact pads  106  coupled to or formed on the package substrate  102 . The contact pads  106  are aligned in rows around edges of the package substrate  102 . Each of the contact pads  106  are shown as having a substantially rectangular shape, although other arrangements and shapes are envisioned. Further, each of the contact pads  106  can have a composition of a single material or a number of different materials, with some embodiments using a highly conductive material, such as gold. In any event, a number of the contact pads  106  will vary depending on how many connections are made in any given integrated circuit package. 
     The package substrate  102  is coupled to the first die  103  using a first die attach  114 , which is a glue or a tape suited for that purpose, although other coupling devices may be used. The second die  104  is coupled to the first die  103  by using a second die attach  115  having a similar, or different, composition as the first die attach  114 . Other embodiments include additional die coupled to the integrated circuit package  100 . Each of the first die  103 , the second die  104 , and any additional die may be a microelectromechanical system (“MEMS”) or an Application Specific Integrated Circuit (“ASIC”), among others. 
     The first die  103  and the second die  104  are electrically coupled to the substrate by the plurality of ink printed wires  108  that extend from at least one of the contact pads  106  to a respective bump  111  on each of the first die  103  or the second die  104 . In  FIG. 1 , the wires  108  have a curvature that corresponds to a curvature of a removed sacrificial layer that was removed during manufacturing. This curvature is different than a standard wire formed using wire bending machinery as the ink printed wires take a shape of an underlying material. 
     In some embodiments, the bumps  111  may be solder balls, while other embodiments replace the bumps  111  with one or more pillars  110 , as in  FIG. 2A-B . Each of the ink printed wires  108 , or other ink printed wires described in the present disclosure are formed using an ink printing wire technique that allows for a pitch  109  between wires  108  that can be less than 100 micrometers with computer-aided design (“CAD”) allowing for accurate placement of the wires  108 . Accordingly, a density of the wires greater than standard wire formation techniques can be achieved using ink printing of the wires. 
     The wires  108  are formed on a sacrificial layer  308 , see  FIG. 3A , which supports the wire until the wire can be cured or otherwise transitioned to a more rigid wire. The sacrificial material  308  is removed during the curing or in a separate step. Each wire can have a composition of a single material or a combination of a variety of materials. For example, each of the ink printed wires  108  or groups of the printed wires may each be formed of a different material. Materials included in the printed wires include, but are not limited to gold, platinum, silver, nickel, copper, aluminum, other metals, carbon, ruthenate, other resistors, single wall carbon nanotubes, multi wall carbon nanotubes, other non-metallic conductors, polyimide, polyvinylpyrrolidone, opaque coatings, UV adhesives, UV acrylics, and other dielectrics and adhesives, organic or non-organic semiconductors, and other general solvents, acids, bases, photo and etch resists, DNA, proteins, and enzymes. 
       FIGS. 2A-B  show a top-down view and a cross-sectional view, through line C-C, of another embodiment of an integrated circuit package  200  having a plurality of ink printed wires  208 . No encapsulant is illustrated in this set of Figures, however, a final product, as will be shown below, will have encapsulant between the wires and the die and covering an entire top surface of the wires, the die, and the package substrate. 
     The package substrate  202  includes one or more contact pads  206  positioned adjacent to edges of the package substrate. A number of contact pads  206  illustrated in this Figure is significantly fewer in number than what can be achieved in a final product using techniques of the present disclosure. The illustrated contact pads provide context for advantages of the techniques of the present disclosure. 
     A die  203  is coupled to the package substrate with a die attach  214 . The die is centrally positioned within the contact pads. The contact pads surround the die and are positioned between the die and the edge of the package substrate. The die has an active surface  211  that includes a plurality of electrical connections that provide signals to and from the die to another device. The die  203  includes one or more pillars or bumps  210  extending slightly above the surface of the die  203 . Each pillar  210  is electrically coupled to a component or components within the die. 
     The pillars or bumps  210  provide a surface onto which a plurality of ink printed  208  wires are formed and are electrically coupled. As will be described in more detail below, the ink printed wires are formed on a sacrificial material this formed on the active surface  211  of the die, on sides of the die and on a portion  213  of the substrate. The encapsulant supports the wires during the printing process, such that each wire has a curvature  215  that corresponds to a curvature of an outer surface of the removed sacrificial layer. As can be seen, the sacrificial layer does not cover the contact pads such that each wire extends from at least one of the pillars  210  to one of the contact pads  206 . 
     In this embodiment, central ones of the pillars  210   a ,  201   b  are coupled to each other with an ink printed wire  209 . This wire is not directly coupled to a contact pad. These pillars may be coupled electrically to adjacent pillars in the die or may simply be tied together. The operation of each die will dictate the arrangement and orientation of the wires and pillars of each die. For example, this ink printing technique provides an opportunity to form wires  207  that one or more substantially 90 degree angles along a length of the wire  207 . Although not shown in this image, having precise control of a physical path of a wire can give the designer flexibility in layout which can be beneficial in dense designs. Said differently, ink printed wires allow for increased density of wires and non-standard wire shapes, such as ones with 90 degree bends from a top down perspective. 
     The package substrate  202  also has a second surface, having a plurality of solder balls  212 , such as in a Ball-Grid Array (“BGA”). The solder balls  212  allow the package substrate  202  to couple with other features of a larger system, such as an electrical coupling to a printed circuit board (“PCB”) or other surface mount device (“SMD”). In other embodiments, the package substrate  202  is be a Quad Flat No-leads arrangement (“QFN”) with a substantially planar pad and connections positioned around the perimeter of the pad, although yet other embodiments may have different arrangements. The contact pads are coupled to the balls  212  through electrical connections in the substrate  202 . 
       FIGS. 3A-3F  are various steps in a process of forming ink printed wires  316  in accordance with an embodiment of the present disclosure. By using a sacrificial layer  308  for ink wire support accurate user control of wire placement is achieved, such as using CAD systems. After the sacrificial layer is removed, increased wire support is achieved from a molding compound  312 , see  FIG. 3F , in a final product. The molding compound substantially surrounds each of the ink printed wires  208 . A wider variety of wire formations are possible within the integrated circuit package  300  using this technique. Such formations can include printing at least one wire  310   a  that follows a curvature of the sacrificial layer  308  or other wires  310   b  that are substantially planar between pillars  306 . This flexibility in designing and arranging the integrated circuit package  300  allows for more connections to be made within one package and an increased density of wires, while also maintaining or improving reliability due to the additional support provided by the molding compound  312  contacting all exposed sides of the ink printed wires  310   a ,  310   b.    
     To provide more detail regarding the use of sacrificial layer  308  and the molding compound  312  surrounding each wire in forming an integrated circuit package  318 , a first exemplary device  300  is described in  FIGS. 3A-F . The process of creating integrated circuit package  318  begins in  FIG. 3A  by attaching a die  304  to a package substrate  302  having a plurality of contact pads  314 . The die  304  includes one or more pillars, bumps, or other raised protrusion  306  extending away from a first surface  305 . The die is attached to the substrate using a die attach or other coupling devices. Although the package substrate  302  may have additional features similar to package substrate  202  of  FIG. 2B , such details are excluded in the interest of brevity. 
     Each of the pillars are evenly spaced from each other arranged on the first surface  305  of the die  304 . Once the die  304  is attached to the package substrate  302 , the sacrificial layer  308  is deposited on a portion  309  of the package substrate  302  and a portion of the die  304 . The portion  309  may correspond to an area that is between the die and the contact pads  314 . In some examples, the sacrificial layer  308  may substantially cover the die  304  between two of the contact pads  314 , although a height of the sacrificial layer  308  can vary with a height of the pillars  306 . In yet other embodiments, the height of the sacrificial layer  308  depends on whether additional sacrificial layers are to be deposited after the thermal sacrificial layer  308 . In this embodiment, the pillars are all a same height, which allows a top surface  311  to remain exposed above the sacrificial layer  308 . 
     The sacrificial layer  308  is a thermal sublimating material, or a sacrificial material comprised of hydrocarbon polymers that sublimate, or transition from a solid phase to a gas phase without experiencing a liquid phase, when heated to a certain temperature. Examples of possible hydrocarbon polymers for use as the sacrificial layer  308  include, but are not limited to: naphthalene, cyclododecane, anthracene, pyre, perylene, and zync acetate. The sacrificial layer  308  is kept in place by a viscosity of the sacrificial material or by masking on the package substrate  302 , or other containment methods, such as a barrier or wall (not shown). In this embodiment, the sacrificial material overlaps a small portion of the contacts. 
     Once the sacrificial layer  308  is in place, one or more ink printed wires  310   a  are printed along a surface  313  of the sacrificial layer  308 , as in  FIG. 3B . The ink printed wires  310  extend from and are electrically coupled to the top surface  311  of the pillars  306  on the die  304  to the contact pads  314  on the package substrate  302 . Other ink printed wires  310   a  extend between pillars  306 .  FIG. 3C  shows an enhanced view of the region A, which includes the ink printed wires  310  formed on the surface  311  of the pillar and the surface  313  of the sacrificial layer  308 . The ink printed wire is formed in direct contact with the top surface  311  and a side surface  315  of the pillar. 
     After printing the ink printed wires  310   a ,  310   b , heat is applied to cause the sacrificial layer  308  to sublimate or otherwise be removed. Similarly, heating causes the ink printed wires  310  to sinter into a plurality of solid ink printed wires  316 , as shown in  FIG. 3D . In other words, sintering is the process of heating the ink printed wires  310  until gas remaining in the ink printed wires  310  is removed, which, in turn, solidifies dense particles suspended in the gas to form the solid ink printed wires  316  that electrically couple the contact pads  314  to the pillars  306 . In some embodiments, sublimating and sintering may happen simultaneously, or by using a constant temperature during heat application. Alternatively, the sublimating or removing and sintering may be in different steps. The solidifying of the wires may occur before the sacrificial material is removed as the sacrificial material provides support for the uncured wires. 
       FIG. 3E  is an enhanced view of the region B after the sacrificial material is removed. The solidified ink printed wire is “floating” above the die and the substrate as it is coupled to the pillars  306  on the die  304 . The solid ink printed wire  316  is contacting the top surface  311  and the side surface  315  of the pillar  306  and having one or more substantially 90 degree angles and having a curvature that generally follows a curvature or shape of the sacrificial layer  308 . 
     Finally, a molding compound  312  is formed over the die  304 , the package substrate  302 , and each of the solid ink printed wires  316  to create the integrated circuit package  318 , as in  FIG. 3F . The molding compound  312  contacts the solid ink printed wires  316  on all sides. The molding compound covers the area  309  and is between the substrate and the wires. The molding compound is also between the die and the wire on the surface of the die. 
     By substantially enclosing the solid ink printed wires  316  in molding compound  312 , the reliability of the integrated circuit package  318  is improved because adhesion issues are minimized, which leads to a lower risk of delamination. Further, the additional support of the molding compound  312  on all sides of the solid ink printed wires  316 , in combination with the free range of motion of an ink printing device, can result in additional wire configurations having significant angles or bends, such as wire  207 , see  FIG. 2A . 
     In other exemplary devices, such as device  400  depicted in  FIGS. 4A-C , at least one secondary wire  413  that is not an ink printed wire may be included with this package. The secondary wire may be formed before or after a plurality of ink printed wires  410 . Standard wires have a circular cross-section, see  FIG. 4D . Ink printed wires have a different cross section, that is rectangular, see  FIG. 4E . According to device  400 , the at least one secondary wire  413  provides power to a die  404  by an electrical coupling between one or more of a plurality of pillars  406  on the die  404  and one or more of a plurality of contact pads  414  on a package substrate  402 . 
     The secondary wire  413  is coupled to a contact pad  415  on the die  404 . This secondary wire  413  is not raised or otherwise elevated off of the surface of the die  404  and thus, a pillar can be omitted from this coupling. 
     After connecting the at least one secondary wire  413 , as in  FIG. 4A , a sacrificial layer  408  is deposited and the ink printed wires  410  are printed on a surface of the sacrificial layer  408  between one or more of the pillars  406  and one or more of the contact pads  414 , as shown in  FIG. 4B . The sacrificial material covers a portion of the secondary wire while another portion is exposed above the sacrificial material. 
     The wires are then solidified, such as by heat to sinter the ink printed wires  410  to form one or more solid ink printed wires  416 . The sacrificial layer  408  is also removed, as in  FIG. 4C . Although not shown, molding compound is placed according to the exemplary embodiments of the present disclosure and it may be possible to connect the at least one secondary wire  413  after printing the ink printed wires  410 . The ink printed wire has a different curvature than the secondary wire as the ink printed wire inherits the curvature of the sacrificial material on which it was formed. 
       FIG. 4D  is a cross section of the secondary wire  413  along the line  4 D- 4 D and  FIG. 4E  is a cross section along the line  4 E- 4 E of one of the solid ink printed wires  416 . The secondary wire  413  is substantially circular with a diameter  429  that varies depending on the type of wire or application, but is consistent along a length of the secondary wire  413 . On the other hand, the cross-section of the solid ink printed wires  416  demonstrates that the solid wires  416  have a substantially rectangular shape, with a width  417  and a height  419 . The ink printed wire  416  may have a consistent width and height throughout or the width  417  or the height  419 , or a combination of both, may change or vary along a length of the solid ink printed wires  416 . 
     For example, the solid ink printed wires  416  could have the width  417  and the height  419  larger at a point where the solid ink printed wires  416  contacts one of the contact pads  414  than where that wire contacts one of the pillars  406 . In other words, the width  417  or the height  419 , or both, can be larger or smaller at either end, or anywhere along the length of the solid wires  416 , which further increases the flexibility in applying the present disclosure. 
       FIGS. 5A-5C  include another exemplary embodiment of a device  500  formed using more than one sacrificial layer  508 ,  528 . In this Figure a die  504  includes a first plurality of pillars  506  and a second plurality of pillars  524 , each of the plurality of pillars having different heights. The second plurality of pillars  524  being taller than the first plurality of pillars, i.e., each second pillar is taller than each first pillar. Ink printed wires  510 ,  530  couple the pillars to ones of a plurality of contact pads  514 ,  526 . 
     The device  500  includes the die  504  coupled to a package substrate  502 . Accordingly, a first sacrificial layer  508  is deposited over a portion of the die  504  and the package substrate  502 , as in  FIG. 5A . A first plurality of ink printed wires  510  are formed on a surface of the first sacrificial layer  508 , extending from a first plurality of contact pads  514  to the first pillars  506 . The second pillars remain uncovered by wires or the first sacrificial material. Once the first sacrificial layer  508  is in place and the first wires are printed, a second sacrificial layer  528  is formed on top of the first sacrificial layer  508 , as in  FIG. 5B . The second sacrificial layer  528  covers the first pillars and the first ink printed wires  510 . A second plurality of ink printed wires  530  are printed on a surface of the second sacrificial layer  528  with the ink printed wires  530  extending from a second plurality of contact pads  526  to the pillars  524 . 
     Once the first sacrificial layer  508  and the second sacrificial layer  528  are in place and the second wires are formed, the first and second sacrificial layers are removed, as in  FIG. 5C . They may be removed by heat, which may also sinter the first ink printed wires  510  and the second ink printed wires  530 , until the first ink printed wires  510  and the second ink printed wires  530  solidify into a first plurality of solid ink printed wires  516  and a second plurality of solid ink printed wires  532 , respectively, as shown in  FIG. 5C . Although not shown, molding compound is then formed around the first and second wires  516 ,  532 , on the die, and on the substrate to form a final package. The second wires  532  are coupled to two pillars, however, they may be only coupled to one pillar. The coupling will be determined by operation of the final product. In other embodiments, multiple layers of sacrificial material and ink printed wires can be used to reach contact pads placed successively further from a center of the die  504 , which increases the possible wire configurations and overall contacts capable in an integrated circuit package. 
     A fourth exemplary device  600 , as in  FIGS. 6A-6D , includes a first die  602  and a second die  604  and multiple sacrificial layers. The first die  602  is coupled to a package substrate  606  and the second die  604  is coupled to the first die  602 . The first die  602  and the second die  604  each have a plurality of pillars, a first plurality of pillars  614  and a second plurality of pillars  616 , as in  FIG. 6A . A first sacrificial layer  612  is formed on the first die and the second die. The first sacrificial layer is between the first die and a first plurality of contact pads  608 . A top surface of the first pillars  614  remains exposed by the first sacrificial layer. A first plurality of ink printed wires  618  are formed on a surface of the first sacrificial layer  612 . The first sacrificial layer  612  abuts a side surface of the second die  604 . Depending on a height of the first pillars the sacrificial layer may be on the top surface of the second die. 
     Similar to how other embodiments employ multiple layers, a second sacrificial layer  603  can be deposited on a portion, or over the entire surface, of the first sacrificial layer  612 , the first wires  618 , and the second die  604 , as in  FIG. 6B . However, the difference in such an embodiment being that the second sacrificial layer  603  may extend from the second plurality of contact pads  610  to the second die pillars  616 , such that the second ink printed wires  620  can be printed from the second die pillars  616  to the second contact pads  610 . Accordingly, this embodiment of the exemplary device  600  could also be applied with additional die and additional pluralities of contact pads. 
     Once the thermal sacrificial layers  612 ,  603  and the ink printed wires  618  and  620  have been formed, heat may be applied to sublimate the thermal sacrificial layers  612 ,  603  and sinter the wires  618 ,  620 , as in other embodiments, to form a first plurality of solid ink printed wires  622  and a second plurality of solid ink printed wires  624 , as in  FIG. 6C . Once the solid wires  622 ,  624  are formed, a molding compound  626  can be placed substantially surrounding the first die  602 , the second die  604 , the package substrate  606  and each of the first solid ink printed wires  622  and the second solid ink printed wires  624  to create an integrated circuit package  601 , as in  FIG. 6D . In some embodiments, each of the first solid ink printed wires  622  and the second solid ink printed wires  624  have a substantially rectangular cross-section that is variable along a length of a given wire, as in other embodiments, with the molding  626  substantially contacting every surface of each wire, or substantially covering each wire. 
     Another exemplary embodiment of a device  700 , as depicted in  FIGS. 7A-D , includes a first set of ink printed wires  722 ,  724  and secondary wires  705   a ,  705   b  and first and second die  702 ,  704 . This device combines several types of die with several types of wires. The secondary wire  705   a  is coupled to a first contact  714  and the secondary wire  705   b  is coupled to a second contact  716  on the second die. The secondary wires may be coupled to planar contact pads as are used in standard wire bonding techniques. On the opposite end of the secondary wires  705   a ,  705   b , a connection is made with a first contact pad  708  and a second contact pad  710 . The secondary wires  705  may be of a different type or composition than the ink printed wires. In some examples, the secondary wires  705  have a substantially circular cross-section and provide power to a first die  702  or a second die  704 , or a combination of both. 
     Once the secondary wires  705  are in place, as in  FIG. 7A , a first sacrificial layer  712  is formed on the package substrate  706 , as in  FIG. 7B . The first sacrificial layer  712  will cover a portion of the secondary wires  705 , and portions of the package substrate  706 , the first die  702  and the second die  704 . After depositing the first sacrificial layer  712 , a first plurality of ink printed wires  718  are formed on the surface of the first sacrificial layer  712  coupling pillars  715   a ,  715   b  from the first die to the contact pad  717 . A second sacrificial layer  703  is formed over the first sacrificial layer  712  and the wires  718 . The second sacrificial layer covers a portion of the secondary wires  705   a ,  705   b . A second plurality of ink printed wires  720  are formed on a surface of the second sacrificial layer  703 , as in  FIG. 7C , extending from the pillar  721  to the contact pad  719 . 
     In some embodiments, part of either the first sacrificial layer  712  or the second sacrificial layer  703  may contact or cover part or substantially all of the secondary wires  705 . After the layers and the printed wires are in place, heat can be applied to solidify the first ink printed wires  718  and the second ink printed wires  720  into a first plurality of solid ink printed wires  722  and a second plurality of solid ink printed wires  724 , respectively, while also removing the first sacrificial layer  712  and the second sacrificial layer  703 , as in  FIG. 7D . Although not shown, molding compound can then be placed according to the exemplary embodiments of the present disclosure. In addition, it may also be possible to add the at least one secondary wire  705  after ink printing, heating the various components, and after removing the sacrificial layer. 
       FIGS. 8A-8C  include another embodiment of a device  800  that includes multiple die, multiple sacrificial layers, and pillars of varying height. An integrated circuit package  800  includes a first die  802  that is coupled to a package substrate  806  that has a first plurality of contact pads  808  and a second plurality of contact pads  810 . A second die  804  is coupled to the first die  802 , as in  FIG. 8A . The first die  802  includes a first plurality of pillars  814  having a first height and a second plurality of pillars  807  having a second, greater height. The second die  804  includes a similar arrangement with the second die  804  having a third plurality of pillars  816  with a first height and a fourth plurality of pillars  809  with a greater, second height. Although depicted with this particular configuration, a height of each of the plurality of pillars can be varied according to particular applications for the integrated circuit package  800 . 
     Once the first die  802  and the second die  804  are coupled to the package substrate  806 , a first sacrificial layer  812  is deposited such that a first plurality of ink printed wires  318  are printed on a surface of the first sacrificial layer  812  between one or more of the second pillars  807  and one or more of the third pillars  816 , or between one or more of the first contact pads  808  and one or more of the first pillars  814 , or any combination thereof. Once the first sacrificial layer  812  and the first ink printed wires  818  are in place, a second sacrificial layer  803  is deposited and a second plurality of ink printed wires  820  are printed between the fourth pillars  809  and the second contact pads  810 , as  FIG. 8B . In such a manner, the present embodiments allow for wires to connect multiple layers to multiple rows of contact pads, even if the contact pads are positioned successively further from a center of die  802 ,  804 . 
     After the layers and the printed wires are in place, heat is used to solidify the first ink printed wires  818  and the second ink printed wires  820  into a first plurality of solid ink printed wires  822  and a second plurality of solid ink printed wires  824 , respectively, while also removing the first sacrificial layer  812  and the second sacrificial layer  803 , as in  FIG. 8C . Finally, although not shown, a molding compound is then formed over the wires and other components to form an integrated circuit package. The molding compound will be positioned between the first die  802  and the wires  822  in opening  815 . The molding compound will be positioned between the wires  822  and the wires  824  and between the wires  824  and a top surface of the first die  802  in opening  813 . The molding compound will be positioned between the wires  822  and the first die and the second die in opening  811 . In addition, the molding compound will completely cover the second die  804 , the contact  810 ,  808 , and the wires  822  to form a complete package. 
       FIG. 9  is a top down view of the ink printed wire  822  that extends from the pillar  809  to the contact pad  810 . The ink printed wire has a first dimension  831  and a second dimension  833  that is wider than the first dimension. The ink printed wire gradually gets wider from the pillar to the contact pad. 
     Each of the pillars described in this disclosure can be replaced by a bump or other contact mechanism that is not has tall. A type of electrical contact selected will depend on the types of die included in the package. A height of each pillar or bump can be different than adjacent pillars or bumps. In some embodiments, the package may include pillars in some locations and bumps in others. This may also include planar contacts pads on the top surface of the die adjacent to the bumps or pillars. 
     The various embodiments described above can be combined to provide further embodiments. All of the U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications referred to in this specification and/or listed in the Application Data Sheet are incorporated herein by reference, in their entirety. Aspects of the embodiments can be modified, if necessary to employ concepts of the various patents, applications and publications to provide yet further embodiments. 
     These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.