Abstract:
An electrical interconnect including a first circuitry layer with a first surface and a second surface. At least a first dielectric layer is printed on the first surface of the first circuitry layer to include a plurality of first recesses. A conductive material is deposited in a plurality of the first recesses to form a plurality of first conductive pillars electrically coupled to, and extending generally perpendicular to, the first circuitry layer. At least a second dielectric layer is printed on the first dielectric layer to include a plurality of second recesses generally aligned with a plurality of the first conductive pillars. A conductive material is deposited in a plurality of the second recesses to form a plurality of second conductive pillars electrically coupled to, and extending parallel the first conductive pillars.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/451,685, filed Mar. 11, 2011, the disclosure of which is hereby incorporated by reference. 
         [0002]    This application is a continuation-in-part of U.S. patent application Ser. No. 13/266,573, titled COMPLIANT PRINTED CIRCUIT AREA ARRAY SEMICONDUCTOR DEVICE PACKAGE, filed Oct. 27, 2011, which is a national stage application under 35 U.S.C. §371 of International Application No. PCT/US2010/036363, titled COMPLIANT PRINTED CIRCUIT AREA ARRAY SEMICONDUCTOR DEVICE PACKAGE, filed May 27, 2010, which claims priority to U.S. Provisional Application No. 61/183,411, filed Jun. 2, 2009, all of which are hereby incorporated by reference in their entireties. 
         [0003]    This application is a continuation-in-part of U.S. patent application Ser. No. 13/318,181, titled COMPLIANT PRINTED CIRCUIT PERIPHERAL LEAD SEMICONDUCTOR PACKAGE, filed Oct. 31, 2011, which is a national stage application under 35 U.S.C. §371 of International Application No. PCT/US2010/036055, titled COMPLIANT PRINTED CIRCUIT PERIPHERAL LEAD SEMICONDUCTOR PACKAGE, filed May 25, 2010, which claims priority to U.S. Provisional Application No. 61/183,365, filed Jun. 2, 2009, all of which are hereby incorporated by reference in their entireties. 
         [0004]    This application is a continuation-in-part of U.S. patent application Ser. No. 13/318,200, title COMPLIANT PRINTED CIRCUIT WAFER LEVEL SEMICONDUCTOR PACKAGE, filed Oct. 31, 2011, which is a national stage application under 35 U.S.C. §371 of International Application No. PCT/US2010/036288, titled COMPLIANT PRINTED CIRCUIT WAFER LEVEL SEMICONDUCTOR PACKAGE, filed May 27, 2010, which claims priority to U.S. Provisional Application No. 61/183,356, filed Jun. 2, 2009, all of which are hereby incorporated by reference in their entireties. 
         [0005]    This application is a continuation-in-part of U.S. patent application Ser. No. 13/318,382, entitled RESILIENT CONDUCTIVE ELECTRICAL INTERCONNECT, filed Oct. 1, 2011, which is a national stage application under 35 U.S.C. §371 of International Application No. PCT/US2010/036313, titled RESILIENT CONDUCTIVE ELECTRICAL INTERCONNECT, filed May 27, 2010, which claims priority to U.S. Provisional Application No. 61/183,335, filed Jun. 2, 2009, all of which are hereby incorporated by reference in their entireties. 
         [0006]    This application is a continuation-in-part of U.S. patent application Ser. No. 13/318,203, entitled COMPLIANT PRINTED CIRCUIT SEMICONDUCTOR TESTER INTERFACE, filed Oct. 7, 2011, which is a national stage application under 35 U.S.C. §371 of International Application No. PCT/US2010/040188, titled COMPLIANT PRINTED CIRCUIT SEMICONDUCTOR TESTER INTERFACE, filed Jun. 28, 2010, which claims priority to U.S. Provisional Application No. 61/221,356, filed Jun. 29, 2009, all of which are hereby incorporated by reference in their entireties. 
     
    
     TECHNICAL FIELD 
       [0007]    The present disclosure relates to a high performance electrical interconnect for electrically coupling least two circuit members using a unique fabrication technique that merges processes used in the printed circuit and semiconductor packaging industries with the flexibility of additive printing technology. 
       BACKGROUND OF THE INVENTION 
       [0008]    Traditional printed circuits are often constructed in what is commonly called rigid or flexible formats. The rigid versions are used in nearly every electronic system, where the printed circuit board (PCB) is essentially a laminate of materials and circuits that when built is relatively stiff or rigid and cannot be bent significantly without damage. 
         [0009]    Flexible circuits have become very popular in many applications where the ability to bend the circuit to connect one member of a system to another has some benefit. These flexible circuits are made in a very similar fashion as rigid PCB&#39;s, where layers of circuitry and dielectric materials are laminated. The main difference is the material set used for construction. Typical flexible circuits start with a polymer film that is clad, laminated, or deposited with copper. A photolithography image with the desired circuitry geometry is printed onto the copper, and the polymer film is etched to remove the unwanted copper. Flexible circuits are very commonly used in many electronic systems such as notebook computers, medical devices, displays, handheld devices, autos, aircraft and many others. 
         [0010]    Flexible circuits are processed similar to that of rigid PCB&#39;s with a series of imaging, masking, drilling, via creation, plating, and trimming steps. The resulting circuit can be bent, without damaging the copper circuitry. Flexible circuits are solderable, and can have devices attached to provide some desired function. The materials used to make flexible circuits can be used in high frequency applications where the material set and design features can often provide better electrical performance than a comparable rigid circuit. 
         [0011]    Flexible circuits are connected to electrical system in a variety of ways. In most cases, a portion of the circuitry is exposed to create a connection point. Once exposed, the circuitry can be connected to another circuit or component by soldering, conductive adhesive, thermo-sonic welding, pressure or a mechanical connector. In general, the terminals are located on an end of the flexible circuit, where edge traces are exposed or in some cases an area array of terminals are exposed. Often there is some sort of mechanical enhancement at or near the connection to prevent the joints from being disconnected during use or flexure. 
         [0012]    In general, flexible circuits are expensive compared to some rigid PCB products. Flexible circuits also have some limitations regarding layer count or feature registration, and are therefore generally only used for small or elongated applications. 
         [0013]    Rigid PCBs and package substrates experience challenges as the feature sizes and line spacing are reduced to achieve further miniaturization and increased circuit density. The use of laser ablation has become increasingly used to create the via structures for fine line or fine pitch structures. The use of lasers allows localized structure creation, where the processed circuits are plated together to create via connections from one layer to another. As density increases, however, laser processed via structures can experience significant taper, carbon contamination, layer-to-layer shorting during the plating process due to registration issues, and high resistance interconnections that may be prone to result in reliability issues. The challenge of making fine line PCBs often relates to the difficulty in creating very small or blind and buried vias. 
       BRIEF SUMMARY OF THE INVENTION 
       [0014]    The present disclosure is directed to a high performance electrical interconnect that will enable next generation electrical performance. The present disclosure merges the long-term performance advantages of traditional PCB and semiconductor packaging with the flexibility of additive printing technology. By combining methods used in the PCB fabrication and semiconductor packaging industries, the present disclosure enables fine line high density circuit structures with attractive cost of manufacture. 
         [0015]    The present disclosure includes adding a bulk material to create the vias and other circuit geometry to supplement or replace the traditional circuit production techniques. This approach enables the production of very small low resistance vias to increase density and reduce line and feature pitch of the circuits as well as a host of electrical enhancements that provide an electrical interconnect that may prove to be superior to the traditional methods. In basic terms, the structure leverages methods used in the semiconductor packaging industry such as stud bumping, ball bonding, flip chip, or pillar termination or discrete particles or spheres of copper, solder or precious metal to act as the via connecting layers within the circuit stack. 
         [0016]    The present high performance electrical interconnect can be treated as a system of its own by incorporating electrical devices or other passive and active function, such as for example, ground planes, power planes, electrical connections to other circuit members, dielectric layers, conductive traces, transistors, capacitors, resistors, RF antennae, shielding, filters, signal or power altering and enhancing devices, memory devices, embedded IC, and the like. In some embodiments, the electrical devices can be formed using printing technology, adding intelligence to the interconnect assembly. 
         [0017]    The present high performance electrical interconnect can be produced digitally, without tooling or costly artwork. The high performance electrical interconnect can be produced as a “Green” product, with dramatic reductions in environmental issues related to the production of conventional flexible circuits. 
         [0018]    The vias and associated circuit geometry can be printed in a variety of shapes and sizes, depending on the terminal structure on the circuit members. The contact members and vias can be positioned at a variety of locations, heights, or spacing to match the parameters of existing connections. 
         [0019]    The use of additive printing processes permits the material set in a given layer to vary. Traditional PCB and flex circuit fabrication methods take sheets of material and stack them up, laminate, and/or drill. The materials in each layer are limited to the materials in a particular sheet. Additive printing technologies permit a wide variety of materials to be applied on a layer with a registration relative to the features of the previous layer. Selective addition of conductive, non-conductive, or semi-conductive materials at precise locations to create a desired effect has the major advantages in tuning impedance or adding electrical function on a given layer. Tuning performance on a layer by layer basis relative to the previous layer greatly enhances electrical performance. 
         [0020]    The present disclosure is directed to an electrical interconnect including a first circuitry layer with a first surface and a second surface. At least a first dielectric layer is printed on the first surface of the first circuitry layer to include a plurality of first recesses. A conductive material is deposited in a plurality of the first recesses to form a plurality of first conductive pillars electrically coupled to, and extending generally perpendicular to, the first circuitry layer. At least a second dielectric layer is printed on the first dielectric layer to include a plurality of second recesses generally aligned with a plurality of the first conductive pillars. A conductive material is deposited in a plurality of the second recesses to form a plurality of second conductive pillars electrically coupled to, and extending parallel the first conductive pillars. 
         [0021]    An IC device can be electrically coupled to a plurality of the second conductive pillars. The IC device can be electrically coupled by one of a flip chip attachment directly to a plurality of third pillars, solder balls, or wire bonding. 
         [0022]    A second circuitry layer is optionally located on the second dielectric layer and electrically coupled with a plurality of the second conductive pillars. At least a third dielectric layer is printed on the second dielectric layer to include a plurality of third recesses generally aligned with a plurality of the second conductive pillars. In one embodiment, portions of the second circuitry layer located in the third recesses are etched away to expose a plurality of the second conductive pillars. In another embodiment, a conductive material deposited in a plurality of the third recesses to form a plurality of third conductive pillars electrically coupled to, and extending parallel the second conductive pillars. An IC device including a plurality of contact pads is electrically coupled to a plurality of the third conductive pillars. The IC device is electrically coupled by one of a flip chip attachment directly to a plurality of third pillars, solder balls, or wire bonding. In yet another embodiment, a third circuitry layer is located on the third dielectric layer. A covering layer extends across the third circuitry layer. The covering layer includes a plurality of openings exposing contact pads on the third circuitry layer configured to electrically couple with an IC device. 
         [0023]    A covering layer optionally extends across the second surface of the first circuitry layer. The covering layer includes a plurality of openings exposing a plurality of contact pads on the first circuitry layer adapted to electrically couple with a PCB. A dielectric material is optionally printing in one or more of the recesses to surround one or more conductive pillars. The conductive material can be one of sintered conductive particles or a conductive ink. 
         [0024]    At least one printed electrical device is optionally located on one of the dielectric layers and electrically coupled to at least a portion of the circuitry layers. 
         [0025]    The present disclosure is also directed to a method of making an electrical interconnect. At least a first dielectric layer is printed on the first surface of a first circuitry layer to include a plurality of first recesses. A conductive material is printed in a plurality of the first recesses to form a plurality of first conductive pillars electrically coupled to, and extending generally perpendicular to, the first circuitry layer. At least a second dielectric layer is printed on the first dielectric layer to include a plurality of second recesses generally aligned with a plurality of the first conductive pillars. A conductive material is printed in a plurality of the second recesses comprising a plurality of second conductive pillars electrically coupled to, and extending parallel the first conductive pillars. 
         [0026]    The present disclosure is also directed to several additive processes that combine the mechanical or structural properties of a polymer material, while adding metal materials in an unconventional fashion, to create electrical paths that are refined to provide electrical performance improvements. By adding or arranging metallic particles, conductive inks, plating, or portions of traditional alloys, the high performance electrical interconnect reduces parasitic electrical effects and impedance mismatch, potentially increasing the current carrying capacity. 
         [0027]    The present high performance electrical interconnect can serve as a platform to add passive and active circuit features to improve electrical performance or internal function and intelligence. For example, electrical features and devices are printed onto the interconnect assembly using, for example, inkjet printing technology or other printing technologies. The ability to enhance the high performance electrical interconnect, such that it mimics aspects of an IC package and a PCB, allows for reductions in complexity for the IC package and the PCB, while improving the overall performance of the interconnect assembly. 
         [0028]    The printing process permits the fabrication of functional structures, such as conductive paths and electrical devices, without the use of masks or resists. Features down to about 10 microns can be directly written in a wide variety of functional inks, including metals, ceramics, polymers and adhesives, on virtually any substrate—silicon, glass, polymers, metals and ceramics. The substrates can be planar and non-planar surfaces. The printing process is typically followed by a thermal treatment, such as in a furnace or with a laser, to achieve dense functionalized structures. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0029]      FIG. 1  is a cross-sectional view of a method of making a high performance electrical interconnects in accordance with an embodiment of the present disclosure. 
           [0030]      FIG. 2  illustrates an optional additional layer on the high performance electrical interconnect of  FIG. 1  in accordance with an embodiment of the present disclosure. 
           [0031]      FIG. 3  illustrates application to a second circuitry layer to the high performance electrical interconnect of  FIG. 1  in accordance with an embodiment of the present disclosure. 
           [0032]      FIG. 4  illustrates an optional dielectric layer on the high performance electrical interconnect of  FIG. 1  in accordance with an embodiment of the present disclosure. 
           [0033]      FIG. 5  illustrates an optional etching step on the high performance electrical interconnect of  FIG. 1  in accordance with an embodiment of the present disclosure. 
           [0034]      FIG. 6  illustrates an electrical interconnect interfaced with a BGA device in accordance with an embodiment of the present disclosure. 
           [0035]      FIG. 7  illustrates an electrical interconnect for a flexible circuit in accordance with an embodiment of the present disclosure. 
           [0036]      FIG. 8  illustrates an electrical interconnect for an IC package in accordance with an embodiment of the present disclosure. 
           [0037]      FIG. 9  illustrates an alternate electrical interconnect for an IC package in accordance with an embodiment of the present disclosure. 
           [0038]      FIG. 10  is a side sectional view of an electrical interconnect in accordance with an embodiment of the present disclosure. 
           [0039]      FIG. 11  is a side sectional view of an alternate electrical interconnect with printed compliant material in accordance with an embodiment of the present disclosure. 
           [0040]      FIG. 12  illustrates an electrical interconnect with optical features in accordance with an embodiment of the present disclosure. 
           [0041]      FIG. 13  illustrates an alternate high performance electrical interconnect with optical features in accordance with an embodiment of the present disclosure. 
           [0042]      FIG. 14  illustrates an alternate high performance electrical interconnect with printed vias in accordance with an embodiment of the present disclosure. 
           [0043]      FIG. 15  illustrates an alternate high performance electrical interconnect with printed electrical devices in accordance with an embodiment of the present disclosure. 
           [0044]      FIG. 16  illustrates an alternate high performance electrical interconnect with printed compliant electrical pads to plug into another connector in accordance with an embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0045]    A high performance electrical interconnect according to the present disclosure may permit fine contact-to-contact spacing (pitch) on the order of less than 1.0 mm pitch, and more preferably a pitch of less than about 0.7 millimeter, and most preferably a pitch of less than about 0.4 millimeter. Such fine pitch high performance electrical interconnects are especially useful for communications, wireless, and memory devices. 
         [0046]    The present high performance electrical interconnect can be configured as a low cost, high signal performance interconnect assembly, which has a low profile that is particularly useful for desktop and mobile PC applications. IC devices can be installed and uninstalled without the need to reflow solder. The solder-free electrical connection of the IC devices is environmentally friendly. 
         [0047]      FIG. 1  is a side cross-sectional view of a method of making an electrical interconnect  50  using additive processes in accordance with an embodiment of the present disclosure.  FIG. 1  shows the basic structure of copper foil circuitry layer  52  only as the base layer. In an alternate embodiment, the circuitry layer  52  can be applied to any substrate or target structural element  54 , such as a traditional PCB or laminated to a stiffening layer or core, such as glass-reinforced epoxy laminate sheets (e.g., FR4). The circuitry layer  52  can be preformed or can be formed using a fine line imaging step is conducted to etch copper foil as done with many PCB processes. 
         [0048]    Dielectric material  56  is applied to surface  58  such that the circuitry  52  is at least partially encased and isolated. The dielectric material  56  can be a film or a liquid dielectric. The dielectric material  56  is typically imaged to expose the desired circuit locations  60 . In some embodiments, it may be desirable to use a preformed dielectric film to leave air dielectric gaps between traces. Recesses  64  in the dielectric layer  56  that expose circuitry  52  can be formed by printing, embossing, imprinting, chemical etching with a printed mask, or a variety of other techniques. 
         [0049]    In a normal construction, the core dielectric material would be processed to enable electro-less copper plating to adhere to the side walls. In the present embodiment, the dielectric  56  is left as a resist to enable electro-less or electrolytic copper plating to adhere only to the exposed portion  60  of the circuitry layer  52  in order to grow pillar or via structure  62  within the imaged openings  64 . The remainder of the interconnect  50  remains un-plated. The support structure  54  acts as a resist to prevent copper plating on the underside  68  of the foil. Alternatively, a resist can be applied to the underside  68  to prevent plating. 
         [0050]    If the electrical interconnect  50  is to be part of a flexible circuit, the base layer  54  can be a material such as polyimide or liquid crystal polymer. If the final product is a rigid circuit board, the base layer  54  can be FR4 or one of many high speed laminates or substrates. If the final product is a semiconductor package, the base layer  54  can be a material such as FR4, BT resin of any one of a variety of laminate or substrate materials. 
         [0051]    The plating process can be controlled to a certain degree, but in some cases with fine pitch geometries and high speed circuits, upper surfaces  66  of the copper pillars  62  may vary in topography or height relative to the field, and the dielectric material  56  may vary in thickness slightly especially if liquid material is used. Consequently, it is preferred to planarize to surfaces  66  of the pillars  62  and the exposed surface  68  of the dielectric  56  between steps to control thickness and flatness of the electrical interconnect  50 . 
         [0052]      FIG. 2  illustrates higher aspect ratio conductive pillars connections formed on the electrical interconnect  50 . The process discussed above is repeated by applying another layer  70  of dielectric  72  that is imaged to expose the upper surface  66  of the previous copper pillar  62 . The imaged openings  74  are then plated as discussed above to create pillar extension  76  of the pillars  62 . Top surface  78  is then planarized as needed. 
         [0053]    In one embodiment, the pillars  76  are planarized to permit die attach point  82  to facilitate flip chip attach of the die  84  to the pillars  76  directly. In another embodiment, exposed surfaces  86  of the pillars can be enlarged to facilitate soldering of the die  84  to the pillars  76 . 
         [0054]      FIG. 3  illustrates circuitry layer  80  is applied to the top surface  78  of the electrical interconnect  50  to create the base for additional routing layers and to facilitate vertical connection to subsequent layers in the stack in accordance with an alternate embodiment of the present disclosure. 
         [0055]      FIG. 4  illustrates resist layer  90  added to the subsequent copper foil  80  in accordance with an alternate embodiment of the present disclosure. The resist layer  90  is imaged to create recesses  92  that expose portions of the copper foil  94  that corresponds with the pillar extensions  76 . The resist layer  90  protects the portions of the circuitry layers  80  that are not to be etched and provides access to the foil intimate to the previous pillar  76 . 
         [0056]      FIG. 5  illustrates a subsequent etch process that removes the copper foil  94  (see  FIG. 4 ) located in the recesses  92  to allow access for the next plating step to join the layers together in accordance with an alternate embodiment of the present disclosure. 
         [0057]    Depending on the resist material  90  and desired final construction, the resist layer  90  can be stripped to provide a level to be planarized as the base of further processing or the resist layer  90  can be left in place provided it is of the proper material type. The exposed regions that provided access for etch and plating can be filled with similar material to seal the layer which can be planarized for further processing if desired. 
         [0058]      FIG. 6  illustrates one possible variation of the electrical interconnect  50 . Recesses  92  are filled with a dielectric material  96  and the surface  98  is planarized to receive circuitry plane  100 . Dielectric layer  102  is deposited on the circuitry plane  100  to expose selective regions  104 . The selective regions  104  are configured to correspond to solder balls  120  on BGA device  122 . In the illustrated embodiment, bottom dielectric layer  106  is optionally deposited on circuitry layer  52  in a manner to expose selective regions  108 . 
         [0059]    In one embodiment, the electrical interconnect  50  is further processed with conventional circuit fabrication processes to create larger diameter through vias or through holes plated  110  as needed, solder mask applied and imaged to expose device termination locations  104 ,  108 , laser direct imaging, legend application etc. 
         [0060]      FIG. 7  illustrate an alternate embodiment in which the electrical interconnect  50  is used in a flexible circuit applications. The electrical interconnect  50  is laminated with ground planes and cover layers  112 ,  114 . In some applications the insulating layers  112 ,  114  are applied by jet printing of polyimide or liquid crystal polymers (LCP) inks as a final layer or as a combination of laminated film and jetted material. 
         [0061]      FIG. 8  illustrates an electrical interconnect  150  for semiconductor packaging applications in accordance with an embodiment of the present disclosure. The stack  152  can be final processed with a variety of options to facilitate electrical connections to IC devices  162 ,  166 ,  172  and to system level attachment to PCB  158 . 
         [0062]    In one embodiment, the pillars  160  are planarized to facilitate flip chip attach to the pillar directly (see e.g.,  FIG. 2 ) or to receive BGA device  162 . In other embodiment, pillars  164  are extended to facilitate direct soldering of IC device die  166  with paste. In yet another embodiment, pillars  168  is wire bonded  170  to the IC device  172 . 
         [0063]    The system interconnect side the structure  180  can be processed to accept a traditional ball grid array attachment  182  for an area array configuration or plated with solder/tin etc. for a no lead peripheral termination. The structure  180  can also be fashioned to have pillars or post extensions  184  to facilitate direct solder attach with paste and provide a natural standoff from the PCB  158 . 
         [0064]      FIG. 9  illustrates an electrical interconnect  200  for a semiconductor package  202  with dielectric materials  204  surrounding the conductive pillars  206  in accordance with an embodiment of the present disclosure. Internal circuits and terminations may also be added by imaging or drilling the core material with a larger opening than needed and filling those openings with dielectric and imaging the desired geometry to facilitate pillar formation. 
         [0065]      FIG. 10  illustrates an alternate electrical interconnect  230  with an insulating layer  232  applied to the circuit geometry  234 . The nature of the printing process allows for selective application of dielectric layer  232  to leave selected portions  236  of the circuit geometry  234  expose if desired. The resulting high performance electrical interconnect  230  can potentially be considered entirely “green” with limited or no chemistry used to produce beyond the direct write materials. 
         [0066]    The dielectric layers of the present disclosure may be constructed of any of a number of dielectric materials that are currently used to make sockets, semiconductor packaging, and printed circuit boards. Examples may include UV stabilized tetrafunctional epoxy resin systems referred to as Flame Retardant 4 (FR-4); bismaleimide-triazine thermoset epoxy resins referred to as BT-Epoxy or BT Resin; and liquid crystal polymers (LCPs), which are polyester polymers that are extremely unreactive, inert and resistant to fire. Other suitable plastics include phenolics, polyesters, and Ryton® available from Phillips Petroleum Company. 
         [0067]    In one embodiment, one or more of the dielectric materials are designed to provide electrostatic dissipation or to reduce cross-talk between the traces of the circuit geometry. An efficient way to prevent electrostatic discharge (“ESD”) is to construct one of the layers from materials that are not too conductive but that will slowly conduct static charges away. These materials preferably have resistivity values in the range of 10 5  to 10 11  Ohm-meters. 
         [0068]      FIG. 11  illustrates an alternate high performance electrical interconnect  250  in accordance with an embodiment of the present disclosure. Dielectric layer  252  includes openings  254  into which compliant material  256  is printed before formation of circuit geometry  258 . The compliant printed material  256  improves reliability during flexure of the electrical interconnect  250 . 
         [0069]      FIG. 12  illustrates an alternate high performance electrical interconnect  260  in accordance with an embodiment of the present disclosure. Optical fibers  262  are located between layers  264 ,  266  of dielectric material. In one embodiment, optical fibers  262  is positioned over printed compliant layer  268 , and dielectric layer  270  is printed over and around the optical fibers  262 . A compliant layer  272  is preferably printed above the optical fiber  262  as well. The compliant layers  268 ,  272  support the optical fibers  262  during flexure. In another embodiment, the dielectric layer  270  is formed or printed with recesses into which the optical fibers  262  are deposited. 
         [0070]    In another embodiment, optical quality materials  274  are printed during printing of the high performance electrical interconnect  260 . The optical quality material  274  and/or the optical fibers  262  comprise optical circuit geometries. The printing process allows for deposition of coatings in-situ that enhance the optical transmission or reduce loss. The precision of the printing process reduces misalignment issues when the optical materials  274  are optically coupled with another optical structure. 
         [0071]      FIG. 13  illustrates another embodiment of a present high performance electrical interconnect  280  in accordance with an embodiment of the present disclosure. Embedded coaxial RF circuits  282  or printed micro strip RF circuits  284  are located with dielectric/metal layers  286 . These RF circuits  282 ,  284  are preferably created by printing dielectrics and metallization geometry. 
         [0072]    As illustrated in  FIG. 14 , use of additive processes allows the creation of a high performance electrical interconnect  290  with inter-circuit, 3D lattice structures  292  having intricate routing schemes. Conductive pillars  294  can be printed with each layer, without drilling. 
         [0073]    The nature of the printing process permit controlled application of dielectric layers  296  creates recesses  298  that control the location, cross section, material content, and aspect ratio of the conductive traces  292  and the conductive pillars  294 . Maintaining the conductive traces  292  and conductive pillars  294  with a cross-section of 1:1 or greater provides greater signal integrity than traditional subtractive trace forming technologies. For example, traditional methods take a sheet of a given thickness and etches the material between the traces away to have a resultant trace that is usually wider than it is thick. The etching process also removes more material at the top surface of the trace than at the bottom, leaving a trace with a trapezoidal cross-sectional shape, degrading signal integrity in some applications. Using the recesses  298  to control the aspect ratio of the conductive traces  292  and the conductive pillars  294  results in a more rectangular or square cross-section, with the corresponding improvement in signal integrity. 
         [0074]    In another embodiment, pre-patterned or pre-etched thin conductive foil circuit traces are transferred to the recesses  298 . For example, a pressure sensitive adhesive can be used to retain the copper foil circuit traces in the recesses  298 . The trapezoidal cross-sections of the pre-formed conductive foil traces are then post-plated. The plating material fills the open spaces in the recesses  298  not occupied by the foil circuit geometry, resulting in a substantially rectangular or square cross-sectional shape corresponding to the shape of the recesses  298 . 
         [0075]    In another embodiment, a thin conductive foil is pressed into the recesses  298 , and the edges of the recesses  298  acts to cut or shear the conductive foil. The process locates a portion of the conductive foil in the recesses  298 , but leaves the negative pattern of the conductive foil not wanted outside and above the recesses  298  for easy removal. Again, the foil in the recesses  298  is preferably post plated to add material to increase the thickness of the conductive traces  292  in the circuit geometry and to fill any voids left between the conductive foil and the recesses  298 . 
         [0076]      FIG. 15  illustrates a high performance electrical interconnect  300  with printed electrical devices  302 . The electrical devices  302  can include passive or active functional elements. Passive structure refers to a structure having a desired electrical, magnetic, or other property, including but not limited to a conductor, resistor, capacitor, inductor, insulator, dielectric, suppressor, filter, varistor, ferromagnet, and the like. In the illustrated embodiment, electrical devices  302  include printed LED indicator  304  and display electronics  306 . Geometries can also be printed to provide capacitive coupling  308 . Compliant material can be added between circuit geometry, such as discussed above, so the present electrical interconnect can be plugged into a receptacle or socket, supplementing or replacing the need for compliance within the connector. 
         [0077]    The electrical devices  302  are preferably printed during construction of the interconnect assembly  300 . The electrical devices  302  can be ground planes, power planes, electrical connections to other circuit members, dielectric layers, conductive traces, transistors, capacitors, resistors, RF antennae, shielding, filters, signal or power altering and enhancing devices, memory devices, embedded IC, and the like. For example, the electrical devices  302  can be formed using printing technology, adding intelligence to the high performance electrical interconnect  300 . Features that are typically located on other circuit members can be incorporated into the interconnect  300  in accordance with an embodiment of the present disclosure. 
         [0078]    The availability of printable silicon inks provides the ability to print electrical devices  302 , such as disclosed in U.S. Pat. No. 7,485,345 (Renn et al.); U.S. Pat. No. 7,382,363 (Albert et al.); U.S. Pat. No. 7,148,128 (Jacobson); U.S. Pat. No. 6,967,640 (Albert et al.); U.S. Pat. No. 6,825,829 (Albert et al.); U.S. Pat. No. 6,750,473 (Amundson et al.); U.S. Pat. No. 6,652,075 (Jacobson); U.S. Pat. No. 6,639,578 (Comiskey et al.); U.S. Pat. No. 6,545,291 (Amundson et al.); U.S. Pat. No. 6,521,489 (Duthaler et al.); U.S. Pat. No. 6,459,418 (Comiskey et al.); U.S. Pat. No. 6,422,687 (Jacobson); U.S. Pat. No. 6,413,790 (Duthaler et al.); U.S. Pat. No. 6,312,971 (Amundson et al.); U.S. Pat. No. 6,252,564 (Albert et al.); U.S. Pat. No. 6,177,921 (Comiskey et al.); U.S. Pat. No. 6,120,588 (Jacobson); U.S. Pat. No. 6,118,426 (Albert et al.); and U.S. Pat. Publication No. 2008/0008822 (Kowalski et al.), which are hereby incorporated by reference. In particular, U.S. Pat. No. 6,506,438 (Duthaler et al.) and U.S. Pat. No. 6,750,473 (Amundson et al.), which are incorporated by reference, teach using ink-jet printing to make various electrical devices, such as, resistors, capacitors, diodes, inductors (or elements which may be used in radio applications or magnetic or electric field transmission of power or data), semiconductor logic elements, electro-optical elements, transistor (including, light emitting, light sensing or solar cell elements, field effect transistor, top gate structures), and the like. 
         [0079]    The electrical devices  302  can also be created by aerosol printing, such as disclosed in U.S. Pat. No. 7,674,671 (Renn et al.); U.S. Pat. No. 7,658,163 (Renn et al.); U.S. Pat. No. 7,485,345 (Renn et al.); U.S. Pat. No. 7,045,015 (Renn et al.); and U.S. Pat. No. 6,823,124 (Renn et al.), which are hereby incorporated by reference. 
         [0080]    Printing processes are preferably used to fabricate various functional structures, such as conductive paths and electrical devices, without the use of masks or resists. Features down to about 10 microns can be directly written in a wide variety of functional inks, including metals, ceramics, polymers and adhesives, on virtually any substrate—silicon, glass, polymers, metals and ceramics. The substrates can be planar and non-planar surfaces. The printing process is typically followed by a thermal treatment, such as in a furnace or with a laser, to achieve dense functionalized structures. 
         [0081]    Ink jet printing of electronically active inks can be done on a large class of substrates, without the requirements of standard vacuum processing or etching. The inks may incorporate mechanical, electrical or other properties, such as, conducting, insulating, resistive, magnetic, semi conductive, light modulating, piezoelectric, spin, optoelectronic, thermoelectric or radio frequency. 
         [0082]    A plurality of ink drops are dispensed from the print head directly to a substrate or on an intermediate transfer member. The transfer member can be a planar or non-planar structure, such as a drum. The surface of the transfer member can be coated with a non-sticking layer, such as silicone, silicone rubber, or Teflon. 
         [0083]    The ink (also referred to as function inks) can include conductive materials, semi-conductive materials (e.g., p-type and n-type semiconducting materials), metallic material, insulating materials, and/or release materials. The ink pattern can be deposited in precise locations on a substrate to create fine lines having a width smaller than 10 microns, with precisely controlled spaces between the lines. For example, the ink drops form an ink pattern corresponding to portions of a transistor, such as a source electrode, a drain electrode, a dielectric layer, a semiconductor layer, or a gate electrode. 
         [0084]    The substrate can be an insulating polymer, such as polyethylene terephthalate (PET), polyester, polyethersulphone (PES), polyimide film (e.g. Kapton, available from DuPont located in Wilmington, Del.; Upilex available from Ube Corporation located in Japan), or polycarbonate. Alternatively, the substrate can be made of an insulator such as undoped silicon, glass, or a plastic material. The substrate can also be patterned to serve as an electrode. The substrate can further be a metal foil insulated from the gate electrode by a non-conducting material. The substrate can also be a woven material or paper, planarized or otherwise modified on at least one surface by a polymeric or other coating to accept the other structures. 
         [0085]    Electrodes can be printed with metals, such as aluminum or gold, or conductive polymers, such as polythiophene or polyaniline. The electrodes may also include a printed conductor, such as a polymer film comprising metal particles, such as silver or nickel, a printed conductor comprising a polymer film containing graphite or some other conductive carbon material, or a conductive oxide such as tin oxide or indium tin oxide. 
         [0086]    Dielectric layers can be printed with a silicon dioxide layer, an insulating polymer, such as polyimide and its derivatives, poly-vinyl phenol, polymethylmethacrylate, polyvinyldenedifluoride, an inorganic oxide, such as metal oxide, an inorganic nitride such as silicon nitride, or an inorganic/organic composite material such as an organic-substituted silicon oxide, or a sol-gel organosilicon glass. Dielectric layers can also include a bicylcobutene derivative (BCB) available from Dow Chemical (Midland, Mich.), spin-on glass, or dispersions of dielectric colloid materials in a binder or solvent. 
         [0087]    Semiconductor layers can be printed with polymeric semiconductors, such as, polythiophene, poly(3-alkyl)thiophenes, alkyl-substituted oligothiophene, polythienylenevinylene, poly(para-phenylenevinylene) and doped versions of these polymers. An example of suitable oligomeric semiconductor is alpha-hexathienylene. Horowitz, Organic Field-Effect Transistors, Adv. Mater., 10, No. 5, p. 365 (1998) describes the use of unsubstituted and alkyl-substituted oligothiophenes in transistors. A field effect transistor made with regioregular poly(3-hexylthiophene) as the semiconductor layer is described in Bao et al., Soluble and Processable Regioregular Poly(3-hexylthiophene) for Thin Film Field-Effect Transistor Applications with High Mobility, Appl. Phys. Lett. 69 (26), p. 4108 (December 1996). A field effect transistor made with a-hexathienylene is described in U.S. Pat. No. 5,659,181, which is incorporated herein by reference. 
         [0088]    A protective layer can optionally be printed onto the electrical devices. The protective layer can be an aluminum film, a metal oxide coating, a polymeric film, or a combination thereof. 
         [0089]    Organic semiconductors can be printed using suitable carbon-based compounds, such as, pentacene, phthalocyanine, benzodithiophene, buckminsterfullerene or other fullerene derivatives, tetracyanonaphthoquinone, and tetrakisimethylanimoethylene. The materials provided above for forming the substrate, the dielectric layer, the electrodes, or the semiconductor layer are exemplary only. Other suitable materials known to those skilled in the art having properties similar to those described above can be used in accordance with the present disclosure. 
         [0090]    The ink-jet print head preferably includes a plurality of orifices for dispensing one or more fluids onto a desired media, such as for example, a conducting fluid solution, a semiconducting fluid solution, an insulating fluid solution, and a precursor material to facilitate subsequent deposition. The precursor material can be surface active agents, such as octadecyltrichlorosilane (OTS). 
         [0091]    Alternatively, a separate print head is used for each fluid solution. The print head nozzles can be held at different potentials to aid in atomization and imparting a charge to the droplets, such as disclosed in U.S. Pat. No. 7,148,128 (Jacobson), which is hereby incorporated by reference. Alternate print heads are disclosed in U.S. Pat. No. 6,626,526 (Ueki et al.), and U.S. Pat. Publication Nos. 2006/0044357 (Andersen et al.) and 2009/0061089 (King et al.), which are hereby incorporated by reference. 
         [0092]    The print head preferably uses a pulse-on-demand method, and can employ one of the following methods to dispense the ink drops: piezoelectric, magnetostrictive, electromechanical, electro pneumatic, electrostatic, rapid ink heating, magneto hydrodynamic, or any other technique well known to those skilled in the art. The deposited ink patterns typically undergo a curing step or another processing step before subsequent layers are applied. 
         [0093]    While ink jet printing is preferred, the term “printing” is intended to include all forms of printing and coating, including: pre-metered coating such as patch die coating, slot or extrusion coating, slide or cascade coating, and curtain coating; roll coating such as knife over roll coating, forward and reverse roll coating; gravure coating; dip coating; spray coating; meniscus coating; spin coating; brush coating; air knife coating; screen printing processes; electrostatic printing processes; thermal printing processes; and other similar techniques. 
         [0094]      Figure 16  illustrates an alternate high performance electrical interconnect  320  with printed compliant material  322  added between circuit geometries  324 ,  326  to facilitate insertion of exposed circuit geometries  328 ,  330  into a receptacle or socket. The compliant material  322  can supplement or replace the compliance in the receptacle or socket. In one embodiment, the compliance is provided by a combination of the compliant material  322  and the exposed circuit geometries  328 ,  330 . 
         [0095]    Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range is encompassed within the embodiments of the disclosure. The upper and lower limits of these smaller ranges which may independently be included in the smaller ranges is also encompassed within the embodiments of the disclosure, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either both of those included limits are also included in the embodiments of the present disclosure. 
         [0096]    Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiments of the present disclosure belong. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the embodiments of the present disclosure, the preferred methods and materials are now described. All patents and publications mentioned herein, including those cited in the Background of the application, are hereby incorporated by reference to disclose and described the methods and/or materials in connection with which the publications are cited. 
         [0097]    The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present disclosure is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dates which may need to be independently confirmed. 
         [0098]    Other embodiments of the disclosure are possible. Although the description above contains much specificity, these should not be construed as limiting the scope of the disclosure, but as merely providing illustrations of some of the presently preferred embodiments of this disclosure. It is also contemplated that various combinations or sub-combinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the present disclosure. It should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the disclosed embodiments of the disclosure. Thus, it is intended that the scope of the present disclosure herein disclosed should not be limited by the particular disclosed embodiments described above. 
         [0099]    Thus the scope of this disclosure should be determined by the appended claims and their legal equivalents. Therefore, it will be appreciated that the scope of the present disclosure fully encompasses other embodiments which may become obvious to those skilled in the art, and that the scope of the present disclosure is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” All structural, chemical, and functional equivalents to the elements of the above-described preferred embodiment(s) that are known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the present claims. Moreover, it is not necessary for a device or method to address each and every problem sought to be solved by the present disclosure, for it to be encompassed by the present claims. Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims.