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Coated copper, method for inhibiting generation of whisker, printed wiring board and semiconductor device

A printed circuit board and copper clad technology, which is applied in the fields of printed circuit, printed circuit, printed circuit manufacturing, etc., can solve problems such as insufficient methods and inability to suppress whisker formation, so as to improve insulation reliability and inhibit whisker growth Effect

Inactive Publication Date: 2007-06-27
MITSUI MINING & SMELTING CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, even if a copper-diffused tin layer of the above-mentioned thickness is formed, and then a pure tin layer is formed on it, there are actually two cases where the formation of whiskers can be suppressed and the formation of whiskers cannot be suppressed.
That is, cited documents 1 and 2 indeed describe effective methods for suppressing whisker formation, but, for example, when the whisker growth limit within 3 months is a linear distance of 15 μm, even if a plating layer is formed according to the records of cited documents 1 and 2, Also can't realize by the content described in patent documents 1 and 2
[0010] In particular, the methods disclosed in the above-mentioned Patent Documents 1 and 2 are not sufficient for the recent standard that the whisker growth limit within 3 months is 15 μm in a straight line distance.

Method used

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  • Coated copper, method for inhibiting generation of whisker, printed wiring board and semiconductor device

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0056]On the surface of a polyimide film having an average thickness of 38 μm, a laminated film in which a copper layer having an average thickness of 8 μm was formed was prepared.

[0057] A photosensitive resin layer is formed on the surface of the copper layer of the laminated film, and a desired pattern is formed by exposing and developing the photosensitive resin.

[0058] Using the formed pattern as a mask material, the copper layer is selectively etched to form the desired wiring pattern.

[0059] On the wiring pattern formed above, a tin-plated layer having an average thickness of 0.35 μm was formed by an electroless plating method. Then, the wiring pattern was heated at 115° C. for 60 minutes to diffuse the copper forming the wiring pattern in the tin plating layer to form a copper diffused tin plating layer. On the wiring pattern of the formed copper diffusion tin plating layer, a tin plating layer with an average thickness of 0.07 μm was formed by an electroless ti...

Embodiment 2

[0065] On the surface of a polyimide film having an average thickness of 38 μm, a laminated film in which a copper layer having an average thickness of 8 μm was formed was prepared.

[0066] A photosensitive resin layer is formed on the surface of the copper layer of the laminated film, and a desired pattern is formed by exposing and developing the photosensitive resin.

[0067] Using the formed pattern as a mask material, the copper layer is selectively etched to form the desired wiring pattern.

[0068] On the wiring pattern formed above, a tin-plated layer having an average thickness of 0.42 μm was formed by electroless plating.

[0069] Then, the wiring pattern on which the tin-plated layer was formed was heated at 115° C. for 60 minutes, and copper was diffused on the tin-plated layer of 0.25 μm, corresponding to 60%. It is 0.42 μm to measure the total thickness of the tin-plated layer using the same method as in Example 1, and the thickness of the pure tin layer is 0.17...

Embodiment 3

[0073] In Example 2, the heating temperature was changed to 125° C., and the heating time was changed to 60 minutes, and a printed wiring board was manufactured by the same method.

[0074] For the printed circuit board obtained, using the same method as in Example 1, the total thickness of the tin-plated layer measured was 0.42 μm, and the thickness of the pure tin layer was 0.13 μm (equivalent to 30% of the whole), therefore, copper The thickness of the diffused tin plating layer was 0.29 μm (corresponding to 70% of the whole).

[0075] After leaving the printed circuit board obtained above at 25° C. for 3 months, the number and length of whiskers generated on the surface were measured using a 500-magnification optical microscope.

[0076] The results are shown in Table 1.

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Abstract

A coated copper being inhibited in the growth of a whisker, which comprises a copper substrate or a copper alloy substrate, a tin layer containing copper diffused therein formed on the surface of said substrate and a pure tin layer formed on the surface of said tin layer containing copper diffused therein, characterized in that said tin layer containing copper diffused therein has a thickness of 55 % or more relative to the sum of those of the tin layer containing copper diffused therein and the pure tin layer; and a printed wiring board and a semiconductor device which has the above coated copper wherein the copper substrate or copper alloy substrate is a wiring pattern. The above coated copper allows the inhibition of the generation of a long whisker having a length more than 15 mu m, which causes short circuit.

Description

technical field [0001] The present invention relates to a method for suppressing the formation of whiskers on a tin-plated copper surface such as a wiring pattern, and to a copper cladding such as a wiring pattern in which whisker growth is suppressed, a printed circuit board having such a wiring pattern, and a semiconductor device. Background technique [0002] In recent years, in order to more compactly mount electronic devices on electronic equipment, the wiring pitch of printed circuit boards and the like has become narrower and narrower. In the vicinity of the inner wires that form the wiring pattern with the narrowest width, and between adjacent wiring patterns The gap becomes narrower than 20µm. [0003] For example, in order to connect a connection portion such as an internal wire to a bump electrode formed in an electronic device, tin needs to be present, and this tin forms a eutectic with gold supplied from the bump electrode. The tin is supplied from the tin-plat...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C28/02C23C10/28C23C18/52C25D5/10C25D7/00H05K1/09
CPCC23C18/52H05K3/244C25D7/123H05K2201/0769C25D7/00C25D5/10H05K2203/1105Y10T428/12903C23C28/02H05K1/09C23C10/28
Inventor 藤井延朗
Owner MITSUI MINING & SMELTING CO LTD