Tin-plated film and method for producing the same

• US 20060016694A1
• Filed: 07/19/2005
• Published: 01/26/2006
• Est. Priority Date: 07/20/2004
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Tanaka, Hisahiro, Ogata, Shigeki
• Granted Patent: US 7,488,408 B2
• Time in Patent Office: Days
• US Class Current: 205/300
• CPC Class Codes: C25D 5/505 of electroplated tin coatings, e.g. by melting
• CPC Class Codes: C25F 3/02 Etching
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 23/49582 Metallic layers on lead frames
• CPC Class Codes: H01L 2924/15173 in a single layer of the multilayer substrate
• CPC Class Codes: Y10S 428/929 Electrical contact feature
• CPC Class Codes: Y10T 428/12715 Next to Group IB metal-base component

Abstract

The present invention has an object to provide a tin-plated film and a method for producing the same, capable of preventing whiskers from being generated and simultaneously preventing the surface of a substrate to be plated, which is not covered with a tin-plated film, from discoloring due to oxidation, by which prevention of whisker generation, suppression of whisker growth, and prevention of discoloring of a substrate to be plated are compatible with simplified operations ensuring excellent productivity. The method is provided with the steps of removing a part of a tin-plated film formed on copper or copper alloy; processing to prevent discoloring of the copper or copper alloy from which the tin-plated film is removed; and applying heat energy to the tin-plated film of the copper or copper alloy which is processed to prevent discoloring.

Claims

1. A method for producing a tin-plated film comprising a step of:

applying heat energy of 59 to 65 J per gram of a substrate to a copper or copper alloy substrate, on which a tin-plated film is formed.

2. The method for producing a tin-plated film according to claim 1, further comprising the steps of:

removing a part of a tin-plated film formed on a copper or copper alloy substrate and treating to prevent discoloring of the copper or copper alloy substrate, from which the tin-plated film is removed, prior to the step of applying the heat energy,

wherein the heat energy is applied to the tin-plated film of the copper or copper alloy substrate for which the discoloring preventing treatment is carried out.

3. The method for producing a tin-plated film according to claim 2, wherein, in the removing step, the tin-plated film is removed by using a remover including (a) carboxylic acid compound and (b) one or more of hydantoin and pentose.

4. The method for producing a tin-plated film according to claim 3, wherein the carboxylic acid compound is one or more of pyrrolidine-2-carboxylic acid, iminodiacetic acid, and glycin.

5. A tin-plated film produced by the method for producing a tin-plated film according to claim 1.

6. A tin-plated film being a tin-plated film formed on a metal substrate, wherein the crystallization orientation plane of the tin-plated film is priority-oriented on a (220) plane, and the film stress is greater than −

7.2 MPa but less than 0 MPa after the tin-plated film is formed.

7. The tin-plated film according to claim 6, wherein, with respect to the film stress, a difference in the film stress in two orthogonal directions at the same measurement portion is 1.0 MPa or less.

8. The tin-plated film according to claim 6, wherein the size of tin grains of the tin-plated film is 1 μ

m or more but 5 μ

m or less, and the mean grain diameter is 2 μ

m or less.

9. The tin-plated film according to claim 7, wherein the size of tin grains of the tin-plated film is 1 μ

m or more but 5 μ

m or less, and the mean grain diameter is 2 μ

m or less.

11. An electronic component including a tin-plated film according to claim 6.

10. A tin-plated film being a tin-plated film formed on a metal substrate, wherein the crystallization orientation plane of the tin-plated film is priority-oriented on a (220) plane, the size of tin grains of the tin-plated film is 1 μ

m or more but 5 μ

m or less, and the mean grain diameter is 2 μ

m or less.

12. A method for producing a tin-plated film, which forms a tin-plated film on a metal substrate, wherein the crystallization orientation plane of a tin-plated film is priority-oriented on a (220) plane, and at the same time, the film stress is made −

7.2 MPa or more but 0 MPa or less after the tin-plated film is formed.

13. The method for producing a tin-plated film according to claim 12, wherein an annealing treatment is carried out after the tin-plated film is formed.

14. The method for producing a tin-plated film according to claim 12, wherein heat energy of 59 to 65 J per gram of a metal substrate is applied.