ALUMINUM NITRIDE SUBSTRATE

• US 20160323992A1
• Filed: 04/25/2016
• Published: 11/03/2016
• Est. Priority Date: 04/09/2014
• Status: Active Grant

• Current Assignee: II-VI Delaware, Inc. (Coherent Corp.)
• Original Assignee: Finisar Corporation (II-VI Incorporated)
• Inventors: Daghighian, Henry Meyer, Bird, Steven C.
• Granted Patent: US 10,470,302 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G02B 2006/12035 Materials
• CPC Class Codes: G02B 2006/121 Channel; buried or the like
• CPC Class Codes: G02B 2006/12104 Mirror; Reflectors or the like
• CPC Class Codes: G02B 2006/12107 Grating
• CPC Class Codes: G02B 2006/12164 Multiplexing; Demultiplexing
• CPC Class Codes: G02B 6/12007 forming wavelength selective elements, e.g. multiplexer, demultiplexer
• CPC Class Codes: G02B 6/122 Basic optical elements, e.g. light-guiding paths
• CPC Class Codes: G02B 6/1221 made from organic materials
• CPC Class Codes: G02B 6/124 Geodesic lenses or integrated gratings
• CPC Class Codes: G02B 6/132 by deposition of thin films
• CPC Class Codes: G02B 6/136 by etching
• CPC Class Codes: G02B 6/42 Coupling light guides with opto-electronic elements
• CPC Class Codes: G02B 6/4214 the intermediate optical element having redirecting reflective means, e.g. mirrors, prisms for deflecting the radiation from horizontal to down- or upward direction toward a device G02B6/4246 takes precedence
• CPC Class Codes: G02B 6/4269 with heat sinks or radiation fins
• CPC Class Codes: H01P 3/081 Microstriplines
• CPC Class Codes: H05K 1/0201 Thermal arrangements, e.g. for cooling, heating or preventing overheating
• CPC Class Codes: H05K 1/0207 using internal conductor planes parallel to the surface for thermal conduction, e.g. power planes
• CPC Class Codes: H05K 1/0209 External configuration of printed circuit board adapted for heat dissipation, e.g. lay-out of conductors, coatings
• CPC Class Codes: H05K 1/024 Dielectric details, e.g. changing the dielectric material around a transmission line
• CPC Class Codes: H05K 1/0274 Optical details, e.g. printed circuits comprising integral optical means H05K1/0269 takes precedence; coupling light guides with opto-electronic components G02B6/42
• CPC Class Codes: H05K 1/028 : Bending or folding regions of flexible printed circuits H05K1/0283 takes precedence
• CPC Class Codes: H05K 1/032 : consisting of one material
• CPC Class Codes: H05K 1/09 : Use of materials for the conductive, e.g. metallic pattern
• CPC Class Codes: H05K 1/115 : Via connections; Lands around holes or via connections H05K1/112 takes precedence
• CPC Class Codes: H05K 2201/0154 : Polyimide
• CPC Class Codes: H05K 2201/09918 : Optically detected marks used for aligning tool relative to the PCB, e.g. for mounting of components
• CPC Class Codes: H05K 3/323 : by applying an anisotropic conductive adhesive layer over an array of pads
• CPC Class Codes: H05K 3/4605 : made from inorganic insulating material
• CPC Class Codes: H05K 3/4611 : by laminating two or more circuit boards H05K3/4652 takes precedence
• CPC Class Codes: H05K 3/4614 : the electrical connections between the circuit boards being made during lamination
• CPC Class Codes: H05K 3/4638 : Aligning and fixing the circuit boards before lamination; Detecting or measuring the misalignment after lamination; Aligning external circuit patterns or via connections relative to internal circuits
• CPC Class Codes: H05K 3/4688 : Composite multilayer circuits, i.e. comprising insulating layers having different properties having a special base or central core H05K3/4602

Abstract

A printed circuit board may include an aluminum nitride (AIN) substrate that includes an AIN thin film and a layer of high-frequency polymer as a carrier substrate of the AIN thin film. The AIN substrate forms a first layer of the printed circuit board. The AIN substrate comprises a heat spreader that laterally spreads out heat from a heat sink on the printed circuit board to form a thermal dissipation path parallel with a signal path on the printed circuit board. The printed circuit board may include a main substrate aligned to and bonded with the AIN substrate. The main substrate may include one or more additional layers of the printed circuit board.

Claims

1. An aluminum nitride (AIN) substrate suitable for use as a first layer of a printed circuit board, comprising:

an AIN thin film having a layer of high-frequency polymer as a carrier substrate; and

a heat spreader forming a thermal dissipation path oriented so as to be capable of being substantially parallel with a signal path on the printed circuit board,

wherein the AIN substrate is bonded to a main substrate that includes one or more additional layers of the printed circuit board.

2. The AIN substrate of claim 1, further comprising a first via coupled to a second via in the main substrate through a conductive path in a thermosetting conductive bonding film.

3. The AIN substrate of claim 1, wherein the AIN thin film includes nitrogen content and is free of fiber weave materials.

4. The AIN substrate of claim 1, further comprising a first loss tangent that is lower than a second loss tangent of fiber weave materials.

5. The AIN substrate of claim 1, further comprising a thickness between 1 micrometer and 100 micrometers.

6. The AIN substrate of claim 1, the layer of high-frequency polymer comprising one of polyimide and kapton.

7. The AIN substrate of claim 1, wherein the heat spreader of the AIN substrate permits lateral spread of heat to avoid loss of routing space within the printed circuit board.

8. The AIN substrate of claim 1, further comprising an optical waveguide included in at least a portion of the AIN substrate surrounded by dielectric material with an index of refraction different from the AIN thin film.

9. The AIN substrate of claim 1, further comprising a metallization of one of nickel (Ni)-based deposition, palladium-based deposition, silver-based deposition, Ni-chrome-electro-vacuum deposition, Tin palladium colloid electro less deposition, and Ni—

P electro less deposition.

10. The AIN substrate of claim 1, further comprising a stack-up of the AIN thin film, the layer of high-frequency polymer, and one or more of a plating, a first patterned mask, a layer of electrolytic copper, a layer of metal deposition, a second patterned mask, or a layer of cladding copper.

11. The AIN substrate of claim 10, wherein the plating includes electro less nickel electro less palladium immersion gold (ENEPIG) plating.

12. The AIN substrate of claim 1, wherein the AIN substrate is at least partially transparent.

13. The AIN substrate of claim 1, further comprising at least one micro strip line deposited on the AIN substrate, the micro strip line comprising a trace width between 10 micrometers to 65 micrometers and a trace pitch width between 15 micrometers to 200 micrometers.

14. An aluminum nitride (AIN) substrate suitable for use as a first layer of a printed circuit board, comprising:

a layer of cladding copper;

an AIN thin film disposed on top of the layer of cladding copper;

a layer of high-frequency polymer disposed on top of the AIN thin film; and

a heat spreader forming a thermal dissipation path, the thermal dissipation path oriented so as to be capable of being substantially parallel with a signal path on the printed circuit board,

wherein the AIN substrate is bonded to a main substrate that includes one or more additional layers of the printed circuit board.

15. An aluminum nitride (AIN) substrate forming an optical waveguide comprising:

a first aluminum nitride (AIN) thin film disposed on a layer of high-frequency polymer; and

a second AIN thin film embedded in the first AIN thin film;

wherein a first nitrogen concentration level of the first AIN thin film is different than a second nitrogen concentration level of the second AIN thin film

16. The AIN substrate of claim 15, wherein the AIN substrate is at least partially transparent and a first index of refraction of the first AIN thin film is different than a second index of refraction of the second AIN thin film.

17. The AIN substrate of claim 16, wherein the AIN substrate is between 85%-90% transparent for wavelengths between 850 nanometers and 1550 nanometers.

18. The AIN substrate of claim 15, wherein the second AIN thin film is embedded in the first AIN thin film to guide a light beam to propagate through the second AIN thin film.

19. The optical waveguide of claim 15, wherein the first AIN thin film and the second AIN thin film form a trench waveguide.

20. The optical waveguide of claim 15, wherein the second AIN thin film is selectively etched to form one or more of:

an etched Bragg grating configured to reflect or transmit an optical signal with a particular wavelength;

or

distributed Bragg reflectors that operate as a wavelength division multiplexing (WDM) filter.