Method of manufacturing cu core ball

Patent metadata

Field	Value
Publication number	US-10370771-B2
Application number	US-201715461866-A
Country	US
Kind code	B2
Filing date	Mar 17, 2017
Priority date	Jan 28, 2014
Publication date	Aug 6, 2019
Grant date	Aug 6, 2019

Abstract

A Cu core ball and a method of manufacturing such a Cu core ball. Purity of the Cu internal ball is at least 99.9% and not greater than 99.995%. A total contained amount of Pb and/or Bi in impurity contained in the Cu ball is equal to or larger than 1 ppm. Its sphericity is at least 0.95. A solder plating film coated on the Cu ball is of Sn solder or a lead free solder alloy whose primary component is Sn. In the solder plating film, a contained amount of U is not more than 5 ppb and that of Th is not more than 5 ppb. A total alpha dose of the Cu ball and the solder plating film is not more than 0./0200 cph/cm2. An arithmetic average roughness of the Cu core ball is equal to or less than 0.3 μm.

First claim

What is claimed is:

1. A method of manufacturing a Cu core ball, comprising:
providing a Cu ball as an inside ball, of least 99.9 mass percent but not more than 99.995 mass percent of said Cu ball being Cu, said Cu ball having a contained amount of U equal to or less than 5 ppb by mass, a contained amount of Th equal to or less than 5 ppb by mass, a total contained amount of at least one of Pb and Bi equal to or larger than 1 ppm by mass, and a sphericity equal to or higher than 0.95;
surrounding the inside ball with a solder plating film of a lead free solder alloy whose primary component is Sn;
thereafter, placing the inside ball, surrounded by the solder plating film, into a quantity of a plating solution and irradiating the inside ball, the solder plating film, and the plating solution with an ultrasonic wave for a period time that is sufficient to provide a Cu core ball having an arithmetic roughness equal to or less than 0.3 μm.

2. The method of claim 1 wherein the lead free solder alloy contains no more than 5 ppb by mass of U and no more than 5 ppb by mass of Th.

3. The method of claim 2 including performing the step of irradiating for a time that is great enough to provide an arithmetic roughness equal to or less than 0.22 μm.

4. The method of claim 2 including the step of covering the inside ball with a plating layer comprising at least one element selected from the group consisting of Ni and Co before performing the step of surrounding the inside ball with a solder plating film.

5. The method of claim 2 , wherein said Cu core ball has an alpha dose equal to or less than 0.0200 cph/cm 2 .

6. The method of claim 1 including performing the step of irradiating for a time that is great enough to provide an arithmetic roughness equal to or less than 0.22 μm.

7. The method of claim 6 including the step of covering the inside ball with a plating layer comprising at least one element selected from the group consisting of Ni and Co before performing the step of surrounding the inside ball with a solder plating film.

8. The method of claim 6 , wherein said Cu core ball has an alpha dose equal to or less than 0.0200 cph/cm 2 .

9. The method of claim 1 including the step of covering the inside ball with a plating layer comprising at least one element selected from the group consisting of Ni and Co before performing the step of surrounding the inside ball with a solder plating film.

10. The method of claim 9 wherein said Cu core ball has an alpha dose equal to or less than 0.0200 cph/cm 2 .

11. The method of claim 1 , wherein said Cu core ball has an alpha dose equal to or less than 0.0200 cph/cm 2 .

Assignees

• Senju Metal Industry Co

Inventors

• Kawasaki Hiroyoshi
• Roppongi Takahiro
• Soma Daisuke
• Sato Isamu

Classifications

• H10W72/252

  comprising solid metals or solid metalloids, e.g. PbSn, Ag or Cu · CPC title

• H10W72/255

  of outermost layers of multilayered bumps, e.g. material of a coating · CPC title

• H10W72/232

  Plan-view shape, i.e. in top view · CPC title

• B22F1/17

  Metallic particles coated with metal · CPC title

• H10W72/223

  characterised by the structure of the outermost layers, e.g. multilayered coatings · CPC title