Liquid metal infiltration rework of electronic assembly

Patent metadata

Field	Value
Publication number	US-12016127-B2
Application number	US-202318354957-A
Country	US
Kind code	B2
Filing date	Jul 19, 2023
Priority date	Oct 22, 2019
Publication date	Jun 18, 2024
Grant date	Jun 18, 2024

Abstract

Provided is a method for removing an electronic component from a printed wiring board. The method comprises applying an embrittlement agent to a lead of an electronic component that is soldered to the printed wiring board. The electronic component is removed from the printed wiring board by breaking the embrittled lead.

First claim

What is claimed is:

1. A system comprising:
a memory; and
a processor communicatively coupled to the memory, wherein the processor is configured to perform a method comprising:
applying an embrittlement agent to a soldered joint of an electronic component that is soldered to a printed wiring board; and
removing the electronic component from the printed wiring board by breaking the embrittled joint.

2. The system of claim 1 , wherein the embrittlement agent is a paste comprising metal that causes liquid metal embrittlement when it infiltrates the joint of the electronic component.

3. The system of claim 1 , wherein the method further comprises:
heating the applied embrittlement agent to a temperature that meets or exceeds a reflow temperature of the embrittlement agent; and
holding the embrittlement agent at the temperature for an amount of time to allow the embrittlement agent to at least partially diffuse into the joint,
wherein removing the electronic component from the printed wiring board is performed after the embrittlement agent has at least partially diffused into the joint.

4. The system of claim 3 , wherein the amount of time and the temperature are based on the composition of the embrittlement agent.

5. The system of claim 1 , wherein removing the electronic component from the printed wiring board comprises applying a mechanical force to break the joint of the electronic component.

6. The system of claim 1 , the method further comprising:
removing, after removing the electronic component, residual alloyed solder from the printed wiring board using a vacuum solder tool;
depositing fresh solder paste on pads on the printed wiring board;
placing a new electronic component on the printed wiring board in place of the electronic component; and
attaching the new electronic component using a reflow soldering process.

7. The system of claim 1 , wherein the embrittlement agent comprises a flux carrier and metal particles.

8. The system of claim 7 , wherein the metal particles include one or more particles selected from the group consisting of elemental copper, a copper alloy, elemental silver, a silver alloy, elemental antimony, and an antimony alloy.

9. The system of claim 7 , wherein the metal particles further comprise one or more particles selected from the group consisting of elemental gallium, a gallium-tin alloy, a gallium-indium alloy, and a gallium-tin-indium alloy.

10. The system of claim 1 , wherein the embrittlement agent further comprises an alcohol emulsion carrier.

11. The system of claim 1 , wherein the embrittlement agent comprises:
a first set of metal particles that cause liquid metal embrittlement when deposited on a metal component; and
a second set of metal particles, wherein the second set of metal particles includes one or more metal particles selected from the group consisting of elemental copper, a copper alloy, elemental silver, a silver alloy, elemental antimony, and an antimony alloy.

12. The system of claim 11 , wherein the first set of metal particles include one or more metal particles selected from the group consisting of elemental gallium, a gallium-tin alloy, a gallium-indium alloy, and a gallium-tin-indium alloy.

13. The system of claim 1 , wherein the embrittlement agent is a preformed sheet.

14. The system of claim 13 , wherein applying the embrittlement agent to the soldered joint comprises:
placing the preformed sheet over the electronic component;
heating the preformed sheet to a temperature that meets or exceeds a reflow temperature of the embrittlement agent; and
holding the embrittlement agent at the temperature for an amount of time to allow the embrittlement agent to at least partially diffuse into the soldered joint.

15. A system comprising:
a memory; and
a processor communicatively coupled to the memory, wherein the processor is configured to perform a method comprising:
applying an embrittlement agent to a soldered joint of an electronic component that is soldered to a printed wiring board;
heating the applied embrittlement agent to a temperature that meets or exceeds a reflow temperature of the embrittlement agent;
holding the embrittlement agent at the temperature for an amount of time to allow the embrittlement agent to at least partially diffuse into the joint; and
removing, after the embrittlement agent has at least partially diffused into the joint, the electronic component from the printed wiring board by breaking the embrittled joint,
wherein the embrittlement agent comprises metal particles, wherein the metal particles include one or more particles selected from the group consisting of elemental copper, a copper alloy, elemental silver, a silver alloy, elemental antimony, and an antimony alloy.

16. The system of claim 15 , wherein the embrittlement agent is a paste comprising metal that causes liquid metal embrittlement when it infiltrates the joint of the electronic component.

17. The system of claim 15 , wherein the amount of time and the temperature are based on the composition of the embrittlement agent.

18. The system of claim 15 , wherein removing the electronic component from the printed wiring board comprises applying a mechanical force to break the joint of the electronic component.

19. The system of claim 15 , wherein the method further comprises:
removing, after removing the electronic component, residual alloyed solder from the printed wiring board using a vacuum solder tool;
depositing fresh solder paste on pads on the printed wiring board;
placing a new electronic component on the printed wiring board in place of the electronic component; and
attaching the new electronic component using a reflow soldering process.

20. The system of claim 15 , wherein:
the embrittlement agent is a preformed sheet; and
applying the embrittlement agent to the soldered joint comprises placing the preformed sheet over the electronic component.

Assignees

• IBM

Inventors

• Hoffmeyer Mark K
• Younger Timothy P

Classifications

• B23K1/018 Primary

  Unsoldering; Removal of melted solder or other residues · CPC title

• H05K2203/043

  Reflowing of solder coated conductors, not during connection of components, e.g. reflowing solder paste · CPC title

• B23K1/0016

  Soldering of electronic components · CPC title

• H05K13/0486 Primary

  Replacement and removal of components · CPC title