Coating for the mitigation of metal whiskers

Patent metadata

Field	Value
Publication number	US-10184054-B2
Application number	US-201615175303-A
Country	US
Kind code	B2
Filing date	Jun 7, 2016
Priority date	Jun 7, 2016
Publication date	Jan 22, 2019
Grant date	Jan 22, 2019

Abstract

A coating for mitigating metal whiskers on a metal surface includes a polymeric coating material; and a metal ion complexing agent impregnated within the polymeric coating material, the metal ion complexing agent having a standard reduction potential (E°) that is greater than a metal in the metal surface.

First claim

What is claimed is:

1. A coating for mitigating tin whiskers on a tin surface, comprising:
a polymeric coating material comprising silver nanoparticles and a complex of a tin ion and a Schiff base-containing compound;
wherein the coating is disposed on a tin surface comprising about 97 to about 100 atomic % (at. %) tin.

2. The coating of claim 1 , wherein the complex of the tin ion and the Schiff base-containing compound has the following formula:
Sn 2+ :R 1 R 2 C═NR 3 ,

wherein a molar ratio of Sn 2+ to R 1 R 2 C=NR 3 is 1:1 or 1:2; R 1 is a hydrogen or an organic side chain; R 2 and R 3 are each independently a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted cycloalkyl group, or a combination thereof; and a substitution on a substituted alkyl group, alkenyl group, alkynyl group, aryl group, or cycloalkyl group is an acrylate group, an acyl halide group, an amide group, an amine group, a carboxylate group, a carboxylate thiol group, an epoxy group, an ester group, an ether group, a halogen, a hydroxamic acid group, a hydroxyl group, a nitrate group, a nitrile group, a phosphate group, a phosphine group, a phosphonic acid group, a silane group, a sulfate group, a sulfide group, a sulfite group, a thiolate group, an azide group, an acetal group, an aldehyde group, a diene group, an imine group, or any combination thereof.

3. The coating of claim 1 , wherein the Schiff base-containing compound has the following structure:

wherein R 1 and R 2 are each independently a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted cycloalkyl group, or a combination thereof; and a substitution on a substituted alkyl group, alkenyl group, alkynyl group, aryl group, or cycloalkyl group is an acrylate group, an acyl halide group, an amide group, an amine group, a carboxylate group, a carboxylate thiol group, an epoxy group, an ester group, an ether group, a halogen, a hydroxamic acid group, a hydroxyl group, a nitrate group, a nitrile group, a phosphate group, a phosphine group, a phosphonic acid group, a silane group, a sulfate group, a sulfide group, a sulfite group, a thiolate group, an azide group, an acetal group, an aldehyde group, a diene group, an imine group, or any combination thereof.

4. The coating of claim 1 , wherein the Schiff base-containing compound chelates tin.

5. The coating of claim 1 , wherein a molar ratio of the tin ion to Schiff base-containing compound is 1:1.

6. The coating of claim 1 , wherein a molar ratio of the tin ion to Schiff base-containing compound is 1:2.

7. A method for mitigating tin whiskers, the method comprising:
providing a substrate having a tin surface comprising about 97 to about 100 atomic % (at. %) tin;
forming a polymeric coating comprising silver nanoparticles and a Schiff base-containing compound; and
disposing the polymeric coating on the tin surface, the Schiff base-containing compound reacting with a tin ion in a tin whisker to form a complex of a tin ion and the Schiff base-containing compound.

8. The method of claim 7 , wherein the polymeric coating has a thickness in a range from about 0.1 to about 20 millimeters (mm).

9. The method of claim 7 , wherein the polymeric coating comprises a symmetric molecule comprising two Schiff base functional groups.

Assignees

• Raytheon Co

Inventors

• Smith David R
• Deppert Thomas M
• Mollberg William C
• Wolf Frank A

Classifications

• C09D183/04

  Polysiloxanes · CPC title

• H05K2201/09872

  Insulating conformal coating · CPC title

• C09D7/63 Primary

  organic · CPC title

• H05K3/285

  Permanent coating compositions · CPC title

• H05K2201/0769

  Anti metal-migration, e.g. avoiding tin whisker growth · CPC title