Printed structures with electrical contact having reflowable polymer core

{
  "publication_number": "US11316086B2",
  "country": "US",
  "kind": "B2",
  "title": "Printed structures with electrical contact having reflowable polymer core",
  "abstract": "A printed structure comprises a device comprising device electrical contacts disposed on a common side of the device and a substrate non-native to the device comprising substrate electrical contacts disposed on a surface of the substrate. At least one of the substrate electrical contacts has a rounded shape. The device electrical contacts are in physical and electrical contact with corresponding substrate electrical contacts. The substrate electrical contacts can comprise a polymer core coated with a patterned contact electrical conductor on a surface of the polymer core. A method of making polymer cores comprising patterning a polymer on the substrate and reflowing the patterned polymer to form one or more rounded shapes of the polymer and coating and then patterning the one or more rounded shapes with a conductive material.",
  "claims": [
    "1. A printed structure comprising: a device comprising device electrical contacts disposed on a common side of the device; and a substrate non-native to the device comprising substrate electrical contacts disposed on a surface of the substrate, wherein at least one of the substrate electrical contacts has a rounded shape, wherein the device electrical contacts are in physical and electrical contact with the substrate electrical contacts, and wherein the at least one of the substrate electrical contacts comprises a polymer core disposed on the surface of the substrate, the polymer core is coated with a contact electrical conductor on a surface of the polymer core, wherein the surface of substrate has a surface energy sufficient to reflow the polymer core into the rounded shape when the polymer core has been heated, and wherein the polymer core is a reflowed bead, wherein each of the at least one of the substrate electrical contacts has a lateral extent over the substrate of no more than 10 μm and the device comprises a fractured or separated device tether.",
    "2. The printed structure of claim 1, wherein the device electrical contacts are substantially planar and are disposed in a common plane.",
    "3. The printed structure of claim 1, wherein the device electrical contacts are substantially planar and are disposed in different planes.",
    "4. The printed structure of claim 1, wherein each of the at least one of the substrate electrical contacts conforms to the shape of a corresponding device electrical contact of the device electrical contacts.",
    "5. The printed structure of claim 1, wherein the polymer core is compliant, conformal, or flexible.",
    "6. The printed structure of claim 1, wherein the polymer core comprises an electrically conductive polymer.",
    "7. The printed structure of claim 1, wherein the contact electrical conductor comprises a metal, a metal alloy, a solder, a transparent conductive oxide, or an electrically conductive polymer.",
    "8. The printed structure of claim 1, wherein the contact electrical conductor is reflowable.",
    "9. The printed structure of claim 1, wherein the contact electrical conductor has a thickness no more than 25% of a lateral extent of the polymer core over the surface of the substrate.",
    "10. The printed structure of claim 1, wherein the contact electrical conductor has a thickness of no more than 250 nm.",
    "11. The printed structure of claim 1, wherein the contact electrical conductor has been wicked along the device electrical contact.",
    "12. The printed structure of claim 1, wherein the device is tilted with respect to the substrate.",
    "13. The printed structure of claim 1, wherein the device is a light-emitting diode.",
    "14. The printed structure of claim 1, wherein the substrate is an intermediate substrate and the printed structure further comprises a system substrate comprising substrate conductors disposed on or in the system substrate, wherein the device is electrically connected to the substrate conductors through the substrate electrical contacts.",
    "15. The printed structure of claim 1, further comprising a second device comprising second device electrical contacts disposed on a common side of the second device, wherein the substrate further comprises second substrate electrical contacts disposed on the surface of the substrate, and wherein at least one of the second substrate electrical contacts has a rounded shape and each of the second device electrical contacts is in electrical and physical contact with one of the second substrate electrical contacts.",
    "16. The printed structure of claim 1, comprising an adhesive disposed between the device and the substrate that adheres the device to the substrate.",
    "17. The printed structure of claim 1, wherein the at least one of the substrate electrical contacts is a plurality of the substrate electrical contacts and the plurality comprises ones of the substrate electrical contacts having different heights or sizes.",
    "18. The printed structure of claim 1, wherein the device is an unpackaged bare die."
  ],
  "description_excerpt": "This application claims the benefit of U.S. Provisional Patent Application No. 63/050,732, filed on Jul. 10, 2020, the disclosure of which is incorporated by reference herein in its entirety.\n\nThis disclosure relates generally to structures and methods for electrically connecting devices (e.g., printed devices) to destination substrates.\n\nElectronic systems typically comprise a substrate, for example a backplane, such as a printed circuit board, on which are assembled electronic components such as integrated circuits, resistors capacitors, inductors, and connectors. The electronic components can be surface mount devices (SMDs) that are typically placed on the backplane together with solder bumps using mechanical pick-and-place equipment and then heated to reflow the solder, thereby adhering the electronic components to the backplane and electrically connecting the electronic components to contact pads or other electrical conductors on the backplane. At present, the smallest surface mount components have dimensions of 600 μm by 300 μm and, for very small and simple electronic devices such as resistors, dimensions of 400 μm by 200 μm. The size of the electrical connection and spacing between contact pads or pins of the electronic devices likewise has a lower limit, for example small solder bumps can have a diameter of 75-150 μm and in extreme cases, solder bumps as small as 30 μm in diameter have been tried. However, there is a demand for increasing electronic system miniaturization with even smaller electronic components and electrical connections.",
  "cpc": [
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  "ipc": [
    "H01L 23/00",
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  ],
  "assignees": [
    "X Display Company Technology Ltd"
  ],
  "inventors": [
    "Christopher Andrew Bower",
    "Ronald S. Cok"
  ],
  "filing_date": "2020-08-28",
  "publication_date": "2022-04-26",
  "grant_date": "2022-04-26",
  "priority_date": "2020-07-10",
  "application_number": "US-202017006674-A",
  "family_id": "79173039",
  "cited_by_count": 5,
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}