Systems and methods for separating components of a multilayer stack of electronic components

• US 9,340,895 B1
• Filed: 06/27/2013
• Issued: 05/17/2016
• Est. Priority Date: 06/27/2013
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Woo, Robyn Lai-Wun
• Primary Examiner(s): PERT, EVAN T
• Application Number:
  US13/929,557
• Time in Patent Office: 1,055 Days
• US Class Current: 1/1
• CPC Class Codes: C25F 5/00 Electrolytic stripping of metallic layers or coatings
• CPC Class Codes: C25F 7/00 Constructional parts, or assemblies thereof, of cells for electrolytic removal of material from objects for both electrolytic coating and removal C25D; Servicing or operating

Abstract

Systems and methods for separating components of a multilayer stack of electronic components are disclosed herein. The multilayer stack of electronic components may include an internal photovoltaic cell and includes a substrate, a sacrificial anode portion, a cathode portion, and an electronic assembly. The sacrificial anode portion extends between the electronic assembly and the substrate and also extends between the electronic assembly and the internal photovoltaic cell, when present. The internal photovoltaic cell, when present, extends between the sacrificial anode portion and the cathode portion. The multilayer stack may be located within an electrically conductive fluid to form an electrochemical cell, and the methods include generating a potential difference between the cathode portion and the sacrificial anode portion and electrochemically oxidizing the sacrificial anode portion to dissolve the sacrificial anode portion within the electrically conductive fluid and separate the electronic assembly from the substrate.

Claims

1. An electrochemical cell, comprising:

an electrically conductive fluid;

a multilayer stack of electronic components that includes an internal photovoltaic cell, a sacrificial anode portion, a cathode portion, and an electronic assembly, wherein the sacrificial anode portion extends between the electronic assembly and the substrate and operatively attaches the electronic assembly to the substrate, wherein the sacrificial anode portion extends between and electrically separates the electronic assembly from the internal photovoltaic cell, wherein the internal photovoltaic cell extends between and electrically separates the sacrificial anode portion from the cathode portion, wherein the multilayer stack is located within the electrically conductive fluid, and further wherein the electrically conductive fluid includes at least one of a liquid solution, an electrolyte solution, a salt solution, and a dilute salt solution; and

a source of electromagnetic radiation, wherein the source of electromagnetic radiation is oriented to direct the electromagnetic radiation onto the internal photovoltaic cell, wherein at least one of a wavelength of the electromagnetic radiation and an intensity of the electromagnetic radiation is selected such that the internal photovoltaic cell generates a potential difference between the cathode portion and the sacrificial anode portion, wherein the potential difference produces dissolution of the sacrificial anode portion within the electrically conductive fluid, and further wherein a portion of the sacrificial anode portion is dissolved within the electrically conductive fluid.

2. A method of separating an electronic assembly from a multilayer stack of electronic components that includes the electronic assembly, a substrate, a cathode portion, and a sacrificial anode portion that is located between the electronic assembly and the substrate and that operatively attaches the electronic assembly to the substrate, wherein the multilayer stack is located within an electrically conductive fluid and forms an electrochemical cell, the method comprising:

generating a potential difference between the cathode portion and the sacrificial anode portion such that the cathode portion forms a cathode of the electrochemical cell and the sacrificial anode portion forms an anode of the electrochemical cell; and

electrochemically oxidizing the sacrificial anode portion to dissolve the sacrificial anode portion within the electrically conductive fluid and separate the electronic assembly from the substrate.

3. The method of claim 2, wherein the multilayer stack includes an internal power source that is located between and in electrical and mechanical communication with the cathode portion and the sacrificial anode portion, wherein the sacrificial anode portion is located between the internal power source and the electronic assembly, and further wherein the generating includes generating the potential difference with the internal power source.

4. The method of claim 3, wherein the internal power source includes an internal photovoltaic cell, and further wherein the method includes:

directing electromagnetic radiation onto the internal photovoltaic cell to initiate the generating.

5. The method of claim 2, further comprising:

establishing a first electrical connection between the cathode portion and a negative terminal of an external power source; and

establishing a second electrical connection between the sacrificial anode portion and a positive terminal of the external power source, wherein the generating includes generating the potential difference with the external power source.

6. The method of claim 2, wherein the multilayer stack is a first multilayer stack, wherein the electronic assembly is a first electronic assembly of the first multilayer stack, wherein the sacrificial anode portion is a first sacrificial anode portion of the first multilayer stack, and further wherein, subsequent to the electrochemically oxidizing, the method further comprises:

forming a second multilayer stack that includes a second electronic assembly, the substrate, and a second sacrificial anode portion that is located between the second electronic assembly and the substrate and that operatively attaches the second electronic assembly to the substrate.

7. The method of claim 6, wherein the method further comprises:

repeating at least the generating and the electrochemically oxidizing to separate the second electronic assembly from the substrate.

8. The method of claim 2, wherein the method further includes selecting a chemical composition of at least one of the cathode portion, the anode portion, and the electrically conductive fluid, wherein the selecting the chemical composition is based, at least in part, on a desired magnitude of the potential difference.

9. The method of claim 8, wherein the multilayer stack includes an internal photovoltaic cell that is in electrical communication with the cathode portion and the sacrificial anode portion, wherein the internal photovoltaic cell defines an operating voltage, and further wherein the desired magnitude of the potential difference is based on the operating voltage of the internal photovoltaic cell.

10. A multilayer stack of electronic components, comprising:

a substrate;

an internal photovoltaic cell;

a sacrificial anode portion;

a cathode portion; and

an electronic assembly;

wherein;

(i) the sacrificial anode portion extends between the electronic assembly and the substrate and operatively attaches the electronic assembly to the substrate;

(ii) the sacrificial anode portion extends between and electrically separates the electronic assembly from the internal photovoltaic cell; and

(iii) the internal photovoltaic cell extends between and electrically separates the sacrificial anode portion from the cathode portion.

11. The multilayer stack of claim 10, wherein the substrate includes at least one of a semiconductor material, a semiconductor wafer, Silicon, Germanium, a III-V semiconductor material, a II-VI semiconductor material, Cadmium Indium Gallium Selenide, Indium Phosphide, and Gallium Arsenide.

12. The multilayer stack of claim 10, wherein the sacrificial anode portion is an epitaxially grown sacrificial anode portion, wherein the internal photovoltaic cell is an epitaxially grown internal photovoltaic cell, and further wherein the electronic assembly is an epitaxially grown electronic assembly.

13. The multilayer stack of claim 10, wherein the internal photovoltaic cell is configured to receive electromagnetic radiation and to generate a potential difference between the sacrificial anode portion and the cathode portion when the electromagnetic radiation is incident upon a side of the substrate that is opposed to the sacrificial anode portion.

14. The multilayer stack of claim 10, wherein the substrate forms an emitter of the internal photovoltaic cell, wherein the internal photovoltaic cell further includes a base, and further wherein the base is located between and electrically separates the substrate from the sacrificial anode portion.

15. The multilayer stack of claim 10, wherein the internal photovoltaic cell is at least one of operatively attached to the substrate, formed on a surface of the substrate, and epitaxially grown from the surface of the substrate.

16. The multilayer stack of claim 15, wherein the internal photovoltaic cell extends between and electrically separates the substrate from the sacrificial anode portion, and further wherein the substrate is an optically transparent substrate that is configured to permit electromagnetic radiation to pass therethrough and be incident upon the internal photovoltaic cell.

17. The multilayer stack of claim 15, wherein the internal photovoltaic cell includes a base and an emitter, and further wherein the emitter extends between and electrically separates the base from the substrate.

18. The multilayer stack of claim 15, wherein the internal photovoltaic cell further includes a back surface field (BSF) layer, wherein the BSF layer extends between and electrically separates a remainder of the internal photovoltaic cell from the sacrificial anode portion.

19. An electrochemical cell, comprising:

an electrically conductive fluid; and

the multilayer stack of claim 10, wherein the multilayer stack is located within the electrically conductive fluid.

20. The electrochemical cell of claim 19 in combination with a source of electromagnetic radiation, wherein the source of electromagnetic radiation is oriented to direct the electromagnetic radiation onto the internal photovoltaic cell, wherein at least one of a wavelength of the electromagnetic radiation and an intensity of the electromagnetic radiation is selected such that the internal photovoltaic cell generates a potential difference between the cathode portion and the sacrificial anode portion, wherein the potential difference produces dissolution of the sacrificial anode portion within the electrically conductive fluid, and further wherein a portion of the sacrificial anode portion is dissolved within the electrically conductive fluid.