Abstract:
Disclosed herein are systems and methods for stacking passive component devices on a substrate. A conductive material is printed onto a first substrate using a fluid ejection device to form a printed passive device according to a predetermined design. The first substrate is attached to a second substrate, such as a die, to form a component for performing a predetermined function. The component may then be tested to determine whether the component formed according to the predetermined design performs the predetermined function. The design may be adjusted in response to the test to improve the performance of the component in performing the predetermined function. Multiple substrates having printed passive devices may be stacked and electrically connected to the die or other substrate in order to increase the number of devices formed on a particular area of that die or other substrate.

Description:
RELATED APPLICATION 
       [0001]    The present application claims priority under 35 U.S.C. §119(e) to U.S. provisional application No. 60/877,787, filed Dec. 29, 2006. 
     
    
     BACKGROUND 
       [0002]    Electronic devices, such as computers, wireless telephones, personal digital assistants, audio/video devices, etc. include integrated circuits (IC) chips that provide active and passive devices. The chip may be bound to a printed circuit board or substrate which connects the product chip to other product chips and/or to system components (e.g., processors, memory, etc) of the device. 
         [0003]    The processes for creating the passive and active devices using semiconductors include expensive and time consuming processes and techniques, including masking, etching, and high temperature steps. Additionally, aspects of the processes specific to creating the active devices are incompatible with those specific to creating passive devices. For example, the high temperature processes involved in creating thin dielectrics and other passive features may cause other deleterious effects, and may even destroy active components such as a transistor. Still further, when a given IC product is being developed using masking techniques, a different mask may have to be developed for each iteration of a design modification. 
       SUMMARY 
       [0004]    Embodiments of the present disclosure include systems and methods for creating a stack of printed passive devices. 
         [0005]    According to one implementation a method is disclosed for creating a stacked passive device on a die. A conductive material is printed onto a first substrate to form a printed passive device according to a predetermined design. The first substrate is attached to a second substrate, such as a die, to form a component for performing a predetermined function. The component may then be tested to determine whether the component formed according to the predetermined design performs the predetermined function. The design may be adjusted in response to the test to improve the performance of the component in performing the predetermined function. An adjusted component may be created by printing a conductive material on a third substrate to form a passive device according to the adjusted design and attaching the third substrate to a forth substrate to form the adjusted component for performing the predetermined function. 
         [0006]    Multiple substrates having printed passive devices may be stacked and electrically connected to the die or other substrate in order to increase the number of devices formed on a particular area of that die or other substrate. 
         [0007]    This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  shows a perspective view of stacked passive devices that are printed using digital techniques. 
           [0009]      FIG. 2  shows is a flow diagram that describes steps in a method of testing a design for a printed passive device stacked on a die, and modifying the design in response to the test. 
           [0010]      FIG. 3  shows a top plan view of an exemplary device having printed passive devices on a carrier substrate and electrical connections to a die or other substrate. 
           [0011]      FIG. 4  shows a cross-sectional view taken along line  4 - 4  of  FIG. 3 . 
           [0012]      FIG. 5  shows a cross-sectional view of an alternative implementation in which solder balls and/or an adhesive layer may be used to connect the passive device carrier substrate to the die. 
           [0013]      FIG. 6  shows a cross-sectional view of another alternative implementation in which a surface of the passive device carrier substrate having passive devices faces the die. 
           [0014]      FIG. 7  shows a cross-sectional view of another alternative implementation in which both wire bonds and solder balls are employed to connect two opposing sides of the passive device carrier substrate to the die. 
           [0015]      FIG. 8  shows a cross-sectional view of another alternative implementation in which two passive device carrier substrates are stacked so that the passive devices on one passive device carrier substrate face toward the die and the passive devices on a second passive device carrier substrate face away from the die. 
           [0016]      FIG. 9  shows a cross-sectional view of another alternative implementation in which two passive device carrier substrates are stacked and wire bonded to the die. 
           [0017]      FIG. 10  shows a cross-sectional view of another alternative implementation in which multiple passive device carrier substrates are stacked and electrical connections are established through wire bonds and solder balls. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    Systems and methods for creating a stacked printed passive device will now be described with more particularity and with reference to the drawings. 
         [0019]      FIG. 1  shows a stack of substrates including printed passive devices. One or more passive devices  110  may be printed on passive device carrier substrate  112 , which may be any suitable inorganic or organic substrate, such as a laminate, circuit board, polymeric tape, resin impregnated glass fiber matrix (commonly referred to as “FR4”), ceramic or the like. The one or more passive devices  110  may be inductors, capacitors, resistors, diodes and/or multilevel interconnects. The passive devices  110  and/or circuit may be designed as one or more deposited layers using a design mechanism that is physically and/or electrically connected to the fluid ejection device. For example, the design mechanism may be a computing device, such as a computer, tablet, or the like. The computing device may direct the fluid ejection device to print the design in a manner similar in nature to an inkjet printing device. The fluid ejection device may deposit one or more layers in order to create one or more printed passive devices  110  on the passive device carrier substrate  112 . Fluid ejection printing may allow the user to quickly create passive devices and circuits without requiring masking, etching, vapor deposition or other techniques, which are relatively expensive and time consuming. 
         [0020]    The fluid ejection device may be any suitable device for the deposition of conductive and dielectric printing, particularly those that that do not require expensive and time consuming mask creation procedures. For example, the fluid ejection device may have thermal or piezoelectric print heads to serve as a “drop-on-demand” mechanism. A temperature-controlled vacuum chuck may be employed so that drops may be deposited onto a heated substrate with a relatively high level of precision. One exemplary fluid ejection printing device is the Dimatix® Materials Printer manufactured by FUJIFILM Dimatix, of Santa Clara, Calif., USA. The conductive materials deposited may be silver, gold, copper, or other suitable conductive materials including metals and alloys. A solvent may be used to deliver the material from the print head in a liquid form. As the conductive material in solution is deposited on the heated substrate, or in a heated environment, the solvent used in the deposition of the conductive material evaporates or burns off and the conductive particles anneal together to form the conductive pattern. 
         [0021]    The fluid ejection device may also be used to deposit dielectric materials. Exemplary dielectric materials include polyimide, benzocyclobutene (BCB), or other suitable insulating material. 
         [0022]    The passive device carrier substrate  112  may be attached to a die  114 , such as a semiconductor die. The die  114  may also carry active devices, circuitry or other carrier substrates. The passive device carrier substrate  112  may be attached using an epoxy or adhesive layer. Additionally or alternatively, the passive device carrier substrate  112  and die  114  may be electrically connected using wire bonding and/or solder ball techniques. For example, wire bond  116  may electrically connect the passive device carrier substrate  112  to the die  114 . The passive device carrier substrate  112  and die  114  may be encapsulated as a package to reduce or eliminate detrimental environmental effects. The passive device carrier substrate  112  and die  114  may be used as a component of a larger system by electrically connecting the package to a base substrate  118 . The passive device carrier substrate  112  and/or passive devices therein may be directly connected to the base substrate  118  by wire bonds  120  or other suitable connection means. 
         [0023]    A method of manufacturing stacked passive devices may be shown by way of the flowchart in  FIG. 2  and with reference to the stacked device shown in  FIG. 1 . A circuit design incorporating passive devices  110  or a design of discrete passive devices  110  may be created or input into a computing device (Block  210 ). The computing device may be used to direct a fluid ejection device to deposit conductive and/or insulating materials onto an organic or inorganic passive device carrier substrate  112  to create the passive devices  110  and/or circuit according to the design created or input (Block  212 ). 
         [0024]    The passive device carrier substrate  112  may be physically and/or electrically connected to a die  114  (Block  214 ). The die  114  may have other passive or active carrier substrates connected thereto. The die  114  may be connected to circuitry on a base substrate  118  by wire bonds  119  or other connection means. 
         [0025]    The passive devices and/other circuitry may be tested (Block  216 ) to determine if the printed passive devices  110  and/or circuit adequately perform the function or functions as per the design created or input (Block  210 ). The testing may be conducted on the passive device carrier substrate  112  before or after it is connected to the die  114  or other passive device carrier substrates, as described below. The passive carrier substrates and die may also be tested before or after connecting the passive carrier substrates and die to the base substrate. According to one example, the passive devices  110  on the passive carrier substrate  112  may be tested using well known techniques such as an open/short or flying probe test. Additionally or alternatively, testing may be performed using a tester that measures specific values for resistors, capacitors, and/or inductors. The passive device carrier substrate  112 , the die  114 , and or the base substrate  118  may also be encapsulated prior to testing. 
         [0026]    If it is determined through testing that the printed design is not performing as intended (Block  216 ), the design may be modified or adjusted (Block  218 ). Thus, for example, if an engineer or technician determines that the inductance obtained by a printed inductor does not meet the requirements of a particular circuit design, the design can be altered so that the inductor is made shorter or longer to achieve the desired inductance value. A new printed passive device carrier substrate  112 ′ can be printed with one or more passive devices  110  according to the adjusted design (Block  220 ). The adjusted design may be a minor iteration of the original design or may be a significant design change based on the results of testing the passive device carrier substrate  112 . The printed passive carrier substrate  112 ′ may replace the original printed passive carrier substrate  112  on the original die  114  or may be attached to a new die for further testing or insertion in a final application (Block  222 ). 
         [0027]      FIG. 3  shows a top plan view of a device having a carrier substrate stacked upon a die. Passive devices such as a resistor  310   a,  inductor  310   b,  and/or capacitor  310   c  may be printed on the surface of a passive device carrier substrate  312  in the manner described above. Conductive traces, which are not illustrated in  FIG. 3  for the sake of simplicity, may be formed on the front or back side of the printed passive device carrier substrate  312 . The printed passive device carrier substrate  312  may be connected to die  314  by wire bonds  318 . 
         [0028]    With reference to  FIGS. 3-10 , it is noted that the passive devices, substrates and other features are shown exaggerated for illustrative purposes and are not intended to reflect a scale. Furthermore, portions of the circuitry have been omitted from the drawings for the sake of simplicity. 
         [0029]      FIG. 4  illustrates a cross-section taken along line  4 - 4  in  FIG. 3  and more clearly shows the attachment of the printed passive device carrier substrate  312  on die  314 . The printed passive device carrier substrate  312  may be attached to a die  314  using an adhesive  316 , such as an epoxy adhesive. Adhesive layer  316  may encapsulate any layers or devices on the backside of passive device carrier substrate. Electrical connections may be made by connecting wire bonds  318  to bonding pads  320  and  322 . The bonding pads  320  and  322  may be connected to further circuitry, which is not illustrated for the sake of simplicity as indicated above. 
         [0030]      FIG. 5  shows a cross-sectional view of an alternative implementation in which solder balls and/or an adhesive layer may be used for connection. Solder balls  518  may be connected to bond pads  519  disposed on or within printed passive device carrier substrate  512  and bond pads  520  disposed on or within die  514 . An adhesive layer  516  may be used to attach printed passive device carrier substrate  512  to die  514 . The adhesive layer  516  may encapsulate any devices or layers, such as conductive traces  522  or solder balls  518 , on the backside of the printed passive device carrier substrate  512 . The devices or layers on the backside maybe connected to the passive devices through vias  524 . 
         [0031]      FIG. 6  shows a cross-sectional view of another alternative implementation in which a side of the printed passive device carrier substrate  612  having passive devices (e.g.,  610 ( a ) and  610 ( b )) is placed facing die  614 . Electrical connection is established through solder balls  618 , which may be connected to bond pads  619  and disposed on or within printed passive device carrier substrate  612  and bond pads  620  disposed on or within die  614 . As above, the bonding pads  619  and  620  may be connected to further circuitry, which is not illustrated for the sake of simplicity. 
         [0032]      FIG. 7  shows a cross-sectional view of another alternative implementation in which both wire bonds  728  and solder balls  718  are employed to connect both sides of the printed passive device carrier substrate  712  having printed passive devices (e.g.,  710 ( a ) and  710 ( b )). Electrical connection is established through solder balls  718 , which may be connected to bond pads  719  and disposed on or within printed passive device carrier substrate  712  and bond pads  720  disposed on or within die  714 . The bonding pads  719  and  720  may be connected to further circuitry, which is not illustrated for the sake of simplicity. The two sides of passive device carrier substrate  724  having circuitry may be connected by vias  724 . 
         [0033]      FIG. 8  shows a cross-sectional view of another alternative implementation in which two printed passive device carrier substrates are formed as a stack. Printed passive device carrier substrate  812 ( a ) is placed with passive devices and/or circuitry facing toward die  814 . Printed passive device carrier substrate  812 ( b ) is placed with the passive devices facing away from the die. Substrate  812 ( a ) may be adhered to die  814  by adhesive layer  826 . Adhesive layer  827  may connect substrate  812 ( b ) and  812 ( a ). The adhesive layers  826  and  827  may provide environmental protection of the passive devices  810 ( a ),  810 ( b ), and any other circuitry underlying the adhesive layers. The substrates  812 ( a ) and  812 ( b ) and die  814  may be adhered in any order. Thus, for example, substrate  812 ( a ) may be adhered to die  814  before or after being adhered to substrate  812 ( b ). 
         [0034]    Solder balls  818  are employed to connect die  814  to printed passive device carrier substrate  812 ( a ). Wire bonds  828  may provide electrical connection between die  814  and printed passive device carrier substrate  812 ( b ). The solder balls  818  may be connected to bond pads  819  disposed on or within printed passive device carrier substrate  812 ( a ) and to bond pads  820  disposed on or within die  814 . The wire bonds may be connected to wire bond pads  830  and  832  disposed on or within die  814 . The bonding pads  819 ,  820 ,  830 , and  832  may be connected to further circuitry, which is not illustrated for the sake of simplicity. 
         [0035]      FIG. 9  shows a cross-sectional view of another alternative implementation in which two printed passive device carrier substrates are stacked and wire bonded to the die. Printed passive device carrier substrate  912 ( a ) may be attached to the die  914  by adhesive layer  926 . Printed passive device carrier substrate  912 ( b ) may be attached to the printed passive device carrier substrate  912 ( a ) by adhesive layer  927 . Wire bonds  928 ( a ) and  928 ( b ) may provide electrical connection between substrates  912 ( a ),  912 ( b ) and the die  914 . 
         [0036]      FIG. 10  shows another cross-sectional view of an alternative implementation in which multiple printed passive device carrier substrates are stacked. Passive device carrier substrate  1012 ( a ) may be connected to die  1014  by adhesive layer  1026 , such as an epoxy or other suitable layer. Solder balls  1018 ( a ) may provide electrical connection. Passive device carrier substrate  1012 ( b ) may be attached to passive device carrier substrate  1012 ( a ) by another adhesive layer  1027 , which may also be an epoxy or other suitable layer. Electrical connection between the printed passive device carrier substrate  1012 ( b ) and die  1014  may be established with solder ball connections  1018 ( b ) and  1018 ( a ) and vias  1024 . 
         [0037]    Wire bonded devices may also be stacked with printed passive device carrier substrates  1012 ( a ) and  1012 ( b ). For example, printed passive device carrier substrate  1012 ( c ) may be attached to printed passive device carrier substrate  1012 ( b ) by adhesive layer  1029 , such as an epoxy or other suitable layer. Electrical connection between the printed passive device carrier substrate  1012 ( c ) and die  1014  may be established with wire bonds  1028 ( a ). Printed passive device carrier substrate  1012 ( d ) may be attached to printed passive device carrier substrate  1012 ( c ) by adhesive layer  1031 , which may also be an epoxy or other suitable layer. Electrical connection between the printed passive device carrier substrate  1012 ( c ) and die  1014  may be established with wire bonds  1028 ( b ). Printed passive device carrier substrate  1012 ( d ) may be made slightly smaller than printed passive device carrier substrate  1012 ( c ) to accommodate the wire bond connections. Adhesive layers  1026 ,  1027 , 1029 , and  1031  may encapsulate passive devices and/or circuitry on the surfaces of the printed passive device substrates. 
         [0038]    Stacking multiple substrates with passive devices allows more passive devices to be formed using the same amount of surface space on the base substrate.  FIG. 10  shows four printed passive device carrier substrates stacked together, but it is conceived that any number of passive device carrier substrates may be formed upon die  1014  in accordance with this disclosure. Furthermore, though solder ball and wire bond connections are shown in  FIGS. 3-10 , it should be understood that any electrical connection may be utilized. For example, the electrical connection may be established using lead frame or other suitable technology. It is also noted that the implementations described herein may also be partially or entirely encapsulated to provide environmental protection. 
         [0039]    Although the invention has been described in language specific to structural features and/or methodological steps, it is to be understood that the invention defined in the appended claims is not necessarily limited to the specific features or steps described. Rather, the specific features and steps are disclosed as preferred forms of implementing the claimed invention.