Preparation and application of pb-free nanosolder

Patent metadata

Field	Value
Publication number	US-2017368643-A1
Application number	US-201615540968-A
Country	US
Kind code	A1
Filing date	Jan 11, 2016
Priority date	Jan 9, 2015
Publication date	Dec 28, 2017
Grant date	—

Abstract

The preparation and use of particulate metallic solder alloy having particles of a single chemical composition is described. The particles of the particulate metallic solder alloy have a bimodal size distribution in which particles in a smaller size range have a largest dimension that is smaller than a smallest dimension of particles in a larger size range of the bimodal distribution. In some examples the particles in the smaller size mode have dimensions in the range of 1 to 100 nm. In some examples, the particles in the larger size mode have dimensions in the range of 2 to 75 microns in dimension. In some examples, a halogen-free flux is used. In some examples, a solvent is used to make a paste.

First claim

What is claimed is:

1 . A composition of matter, comprising:
a particulate metallic solder alloy having particles of a single chemical composition, said particles of said particulate metallic solder alloy having a bimodal size distribution in which particles in a smaller size range have a largest dimension that is smaller than a smallest dimension of particles in a larger size range of said bimodal distribution.

2 . The composition of matter of claim 1 , wherein said particles in said smaller size range of said particulate metallic solder alloy are in the range of 1-100 nanometers.

3 . The composition of matter of claim 1 , wherein said particles in said larger size range of said particulate metallic solder alloy are in the range of 2-75 microns.

4 . The composition of matter of claim 1 , further comprising a flux and a solvent, the combination of said particulate metallic solder alloy, said flux and said solvent in the form of a solder paste.

5 . The composition of matter of claim 4 , wherein said flux is a halogen-free flux.

6 . The composition of matter of claim 5 wherein said particulate metallic solder alloy is present in 50 to 90 weight percent, said halogen-free flux is present in 10 to 50 weight percent, and said solvent is present in 0.1 to 5 weight percent.

7 . The composition of matter of claim 1 , further comprising a flux.

8 . The composition of matter of claim 7 , wherein said flux is a halogen-free flux.

9 . The composition of matter of claim 8 , wherein said particulate metallic solder alloy is present in 50 to 90 weight percent and said halogen-free flux is present in 10 to 50 weight percent.

10 . The composition of matter of claim 1 , wherein said fraction of said particulate metallic solder alloy particles in said smaller size range are present in 0.5 to 10 weight percent.

11 . The composition of matter of claim 1 , wherein said particulate metallic solder alloy is a tin-silver-copper alloy.

12 . The composition of matter of claim 1 , wherein said particulate metallic solder alloy is a tin-silver alloy.

13 . The composition of matter of claim 1 , wherein said particulate metallic solder alloy is a tin-copper alloy.

14 . The composition of matter of claim 1 , wherein said particulate metallic solder alloy is a tin-indium alloy.

15 . The composition of matter of claim 1 , wherein said particulate metallic solder alloy is a tin-gold alloy.

16 . The composition of matter of claim 1 , wherein said particulate metallic solder alloy is a tin-bismuth alloy.

Assignees

• Univ Massachusetts

Inventors

• Gu Zhiyong
• Gao Fan
• Wernicki Evan
• Campelli Jonathan

Classifications

• B23K35/025 Primary

  Pastes, creams or slurries · CPC title

• B23K35/02

  characterised by mechanical features, e.g. shape · CPC title

• B23K35/26

  with the principal constituent melting at less than 400°C · CPC title

• H01R43/02

  for soldered or welded connections · CPC title

• C22C13/00

  Alloys based on tin · CPC title