Fabrication of electronic devices including flexible electrical circuits

• US 8,173,490 B2
• Filed: 01/18/2011
• Issued: 05/08/2012
• Est. Priority Date: 12/12/2008
• Status: Active Grant

• Current Assignee: Premitec, Inc.
• Original Assignee: Helmut Eckhardt, Stefan Ufer
• Inventors: Eckhardt, Helmut, Ufer, Stefan
• Primary Examiner(s): Smith, Zandra
• Assistant Examiner(s): PATTON, PAUL E
• Application Number:
  US13/008,338
• Publication Number:
  US 20110117703A1
• Time in Patent Office: 476 Days
• Field of Search: 257690-693, 257/E23.055, 257/E23.065, 257/E23.177, 438/118
• US Class Current: 438/118
• CPC Class Codes: A61N 1/05 for implantation or insertion into the body, e.g. heart electrode A61N1/06 takes precedence
• CPC Class Codes: A61N 1/375 Constructional arrangements, e.g. casings
• CPC Class Codes: H01L 21/76898 formed through a semiconductor substrate
• CPC Class Codes: H01L 2224/04105 Bonding areas formed on an encapsulation of the semiconductor or solid-state body, e.g. bonding areas on chip-scale packages
• CPC Class Codes: H01L 2224/20 Structure, shape, material or disposition of high density interconnect preforms
• CPC Class Codes: H01L 23/481 Internal lead connections, e.g. via connections, feedthrough structures
• CPC Class Codes: H01L 23/4985 Flexible insulating substrates H01L23/49572 and H01L23/49855 take precedence
• CPC Class Codes: H01L 24/19 Manufacturing methods of high density interconnect preforms
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/01005 Boron [B]
• CPC Class Codes: H01L 2924/01006 Carbon [C]
• CPC Class Codes: H01L 2924/01013 Aluminum [Al]
• CPC Class Codes: H01L 2924/01015 Phosphorus [P]
• CPC Class Codes: H01L 2924/01023 Vanadium [V]
• CPC Class Codes: H01L 2924/01024 Chromium [Cr]
• CPC Class Codes: H01L 2924/01027 Cobalt [Co]
• CPC Class Codes: H01L 2924/01029 Copper [Cu]
• CPC Class Codes: H01L 2924/01033 Arsenic [As]
• CPC Class Codes: H01L 2924/01046 Palladium [Pd]
• CPC Class Codes: H01L 2924/01047 Silver [Ag]
• CPC Class Codes: H01L 2924/01049 : Indium [In]
• CPC Class Codes: H01L 2924/01077 : Iridium [Ir]
• CPC Class Codes: H01L 2924/01078 : Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/014 : Solder alloys
• CPC Class Codes: H01L 2924/09701 : Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H01L 2924/10253 : Silicon [Si]
• CPC Class Codes: H01L 2924/10329 : Gallium arsenide [GaAs]
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/1461 : MEMS
• CPC Class Codes: H01L 2924/1815 : Shape
• CPC Class Codes: H01L 2924/19041 : being a capacitor
• CPC Class Codes: H01L 2924/19042 : being an inductor
• CPC Class Codes: H01L 2924/19043 : being a resistor
• CPC Class Codes: H01L 2924/30107 : Inductance

Abstract

A packaged electronic device includes a die, a flexible circuit structure, and a barrier film disposed on the die. The die includes die circuitry and electrical contacts. The flexible circuit structure is bonded directly to the die, and includes electrical conductors encapsulated by structural layers. Each electrical conductor contacts a respective electrical contact. The electronic device is encapsulated by the barrier film and one or more of the structural layers.

Claims

1. A method for fabricating a packaged electronic device, the method comprising:

fabricating a flexible circuit structure on a first substrate surface of a substrate by;

depositing a first structural layer on the first substrate surface wherein the first structural layer is bonded directly to the first substrate surface;

forming a plurality of electrical conductors on the first structural layer and in signal communication with die circuitry of the substrate; and

depositing a second structural layer on the electrical conductors,

wherein the electrical conductors are encapsulated by the first structural layer and the second structural layer, and the flexible circuit structure in combination with the substrate forms an electronic device; and

depositing a barrier film on a second substrate surface of the substrate opposite to the first substrate surface, and on an outer lateral surface of the substrate extending generally between the first substrate surface and the second substrate surface, wherein the electronic device is encapsulated by the barrier film and one or more of the first structural layer and the second structural layer.

2. The method of claim 1, wherein the die circuitry is formed at the first surface, and fabricating the flexible circuit structure embeds the die circuitry between the flexible circuit structure and the substrate.

3. The method of claim 2, wherein the substrate includes a plurality of electrical contacts disposed at the first substrate surface in signal communication with the die circuitry, forming the plurality of electrical conductors places the electrical conductors in signal communication with the respective electrical contacts, and fabricating the flexible circuit structure embeds the electrical contacts between the flexible circuit structure and the substrate.

4. The method of claim 1, wherein the die circuitry is formed at the second substrate surface, depositing the barrier film embeds the die circuitry between the barrier film and the second substrate surface, the substrate includes a plurality of electrical interconnects in signal communication with the die circuitry and extending through the thickness of the substrate from the first substrate surface to the second substrate surface such that the electrical interconnects define respective electrical contact sites at the second substrate surface, forming the plurality of electrical conductors places the electrical conductors in signal communication with the respective electrical contact sites, and fabricating the flexible circuit structure embeds the electrical contact sites between the flexible circuit structure and the substrate.

5. The method of claim 1, wherein fabricating the flexible circuit structure includes chemically bonding the flexible circuit structure to the substrate.

6. The method of claim 1, wherein depositing the first structural layer includes chemically bonding the first structural layer to the first substrate surface.

7. The method of claim 1, wherein the composition of the first substrate surface includes a material selected from the group consisting of silicon, glass, quartz, ceramic, metals, inorganic oxides, inorganic nitrides, and polyimides, and the composition of the first structural layer includes a polymer and an adhesion promoter configured to promote chemical bonding to the composition of the first surface.

8. The method of claim 1, wherein the composition of the first substrate surface includes a material selected from the group consisting of silicon, glass, quartz, ceramic, metals, inorganic oxides, inorganic nitrides, and polyimides, the composition of the first structural layer includes a polymer, and further comprising applying an adhesive coating to at least one of the first substrate surface and the first structural layer to promote chemical bonding of the first structural layer to the first substrate surface.

9. The method of claim 1, wherein the first structural layer includes a polymer selected from the group consisting of polyimide, copolymers of polyimide and blends of polyimide.

10. The method of claim 9, wherein depositing the first structural layer includes spin-coating the polymer.

11. The method of claim 1, wherein the second structural layer includes a polymer selected from the group consisting of polyimide, copolymers of polyimide and blends of polyimide.

12. The method of claim 11, wherein depositing the second structural layer includes spin-coating the polymer.

13. The method of claim 1, wherein depositing the barrier film comprises depositing a polymer selected from the group consisting of polyimide, copolymers of polyimide and blends of polyimide.

14. The method of claim 13, wherein the depositing the barrier film comprises spraying a polymer precursor solution through a nozzle while spinning the substrate.

15. The method of claim 13, wherein the depositing the barrier film further comprises depositing an additional film on the polymer.

16. The method of claim 15, wherein the additional film includes diamond-like carbon.

17. The method of claim 1, wherein the barrier film is a first barrier film, and further comprising depositing a second barrier film on the second structural layer, wherein the electronic device is encapsulated by the first barrier film and the second barrier film.

18. The method of claim 17, wherein depositing at least one of the first barrier film and the second barrier film includes depositing a polymer selected from the group consisting of polyimide, copolymers of polyimide and blends of polyimide.

19. The method of claim 17, wherein depositing at least one of the first barrier film and the second barrier film includes depositing a polymer selected from the group consisting of polyimide, copolymers of polyimide and blends of polyimide, followed by depositing an additional barrier film on the polymer.

20. The method of claim 19, wherein the additional film includes diamond-like carbon.

21. The method of claim 1 further comprising, prior to depositing the first structural layer, depositing a sacrificial release film on the first substrate surface wherein depositing the first structural layer also deposits the first structural layer on the sacrificial release film, and after depositing the second structural layer, removing the sacrificial release film and removing a portion of the substrate to form a die directly bonded to the flexible circuit structure, the die including the die circuitry in signal communication with the flexible circuit structure.