JP2005325385A - Bright plated film with tin-bismuth alloy for electronic parts such as connector and semiconductor parts, and bright plating bath of tin-bismuth alloy for electronic parts such as connector and semiconductor parts - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems that a plated film with an Sn-Bi alloy adopted in conventional connector parts has a dull/semi-gloss appearance and causes failure due to the appearance, is shaved when a product is assembled and transported, because of being formed by using a dull plating bath which is considered to give the film low hardness for the connector parts, and causes an error or an erratic behavior when information on the product is read by a sensor, due to the lack of glossiness; and that an existing bath for plating a tin-bismuth alloy has a composition containing a large amount of an organic matter, consequently causes the discoloration and coagulation during reflowing of the plated film, and has not been used for production. <P>SOLUTION: The bright plated film with a tin-bismuth alloy for electronic parts includes 99.9-95.0% Sn and 0.1-5.0% Bi, has a glossiness of 0.8 or higher, and is formed into a thickness of 2.0 μm. Then, the film does not cause the coagulation during reflowing at 230°C to 300°C and the discoloration. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a bright tin / bismuth alloy plating bath for electronic parts such as connectors or semiconductor parts, and a bright tin / bismuth alloy plating bath for electronic parts such as connectors or semiconductor parts.

In general, among the plating performed on electronic parts, tin plating is mainly used in weak electrical industry and electronic industry parts as a film for improving solderability and a film for etching resist. In particular, recently, tin plating has been cited as an alternative to Sn (tin) -Pb (lead) alloy plating because of respect for environmental conservation. Conventionally, the degree of gloss is increased by plating Sn with Bi added.
Further, the following patent documents are related to the present invention.
Japanese Patent Laid-Open No. 08-225985 (paragraph “0030”) Japanese Unexamined Patent Publication No. 2003-147580 (paragraph "Claim 1")

In paragraph “0030” of the above “Patent Document 1 (Japanese Patent Laid-Open Publication No. 08-225985)”, as a brightener, a conventionally known tin plating bath, solder plating bath, etc. As an active ingredient amount, It may be about 0.001 to 1 g / L. "
Further, in “Claim 4” of “Patent Document 2 (Japanese Unexamined Patent Publication No. 2003-147580)”, “the tin or tin alloy plating film as the third layer has a thickness of 2.0 μm or less. It is characterized by ... ".

However, compared with the above-mentioned “Patent Document 1”, in the present invention, the Sn—Bi plating bath contains only 0.1 mg / L or less as the effective amount of the brightener. Different bath composition.
In the present invention, no chemical as shown in “Patent Document 1” is used, and in “Patent Document 1”, the content of the organic substance of the present invention is reduced. This is different from the policy of obtaining a plated coating.

  Next, in “Patent Document 2”, Sn-Bi plating of the present invention is agglomeration of mottled patterns or the like in a plating film of 2.0 or more as shown in “Claim 1”. However, “Patent Document 2” is not similar to this. In addition, “Patent Document 2” is a method in which a tin or tin alloy plating film is formed in two layers as a method for suppressing aggregation, and a plating of 2.0 μm or more is applied as a single layer as in the present invention. This is different from the one that prevents aggregation.

Of the electronic components described above, the Sn—Bi alloy plating employed in the conventional connector component has a matte / semi-glossy appearance and a defect associated therewith. First, the problem of occurrence of burrs during molding in semiconductor components occurs because burrs are difficult to remove when the glossiness is low. Since the connector parts employ matte plating, which is generally considered to have a low hardness, there is a problem of scraping during assembly and transportation of products. In addition, there is a problem that an error or malfunction occurs when reading a product with a sensor due to lack of gloss. As the plating bath, the existing bright Sn-Bi alloy plating is not in a state where it can be used in production such as discoloration and aggregation during reflow because of the bath composition containing a large amount of organic matter.

Therefore, the present invention is provided in order to solve the conventional problems and achieve the object of the invention.

The first aspect of the present invention is a bright tin / bismuth alloy plating film for electronic parts such as connector parts or semiconductor parts. Sn is 99.9 to 95.0% and Bi is 0.1 to 5.0%. And a gloss Sn-Bi alloy plating having a glossiness of 0.8 or more is applied to a thickness of 2.0 μm so that aggregation and plating discoloration do not occur under reflow conditions of 230 ° C. to 300 ° C. Is.

A second aspect of the present invention is a bright tin / bismuth alloy plating film for electronic parts such as connectors or semiconductor parts, wherein Bi is 0.1 to 5.0% with respect to Sn 99.9 to 95.0%. In addition, a glossy Sn—Bi alloy plating having a glossiness of 0.8 or more is applied so as not to cause aggregation and plating discoloration due to a change with time in a room temperature state.

In the third aspect of the present invention, in the bright tin / bismuth alloy plating bath for electronic parts such as connectors or semiconductor parts, the amount of the first brightener added to the Sn—Bi plating solution is 0.01 mg / L or less. Using this, bright Sn—Bi alloy plating is performed so that aggregation and plating discoloration do not occur under reflow conditions of 230 ° C. to 300 ° C.

The fourth aspect of the present invention is that in the bright tin / bismuth alloy plating bath for electronic parts such as connectors or semiconductor parts, the amount of the first brightener added to the Sn—Bi plating solution is 0.01 mg / L. Therefore, a bright Sn—Bi alloy plating is used to prevent the occurrence of agglomeration and plating discoloration due to aging at room temperature.

Since the present invention has the above-described configuration, the plating film obtained by the plating bath for electronic components such as connectors and semiconductor components has a low content of organic matter, so that no melt failure occurs and the plating surface is uneven. Generation of (mottled) patterns is suppressed. In addition, the occurrence of discoloration over time can be prevented.

And in the electronic component to be mounted which is subjected to the bright Sn—Bi alloy plating with the bonding material in place of Pb, Sn is contained at a ratio of 0.1 to 5.0% with respect to 99.9 to 95.0%. In addition, since it is a bright Sn-Bi alloy plating bath and film having a glossiness of 0.8 or more, the main brightener content is 0.01 mg / L and it is extremely small, and it does not contain environmentally hazardous substances. It is also effective as an environmental measure.

The best mode for carrying out the present invention will be described below by way of examples. First, the Sn—Bi alloy plating bath will be described. The Sn—Bi alloy plating bath having the composition shown in “Table 1” was prepared, the connector parts and the semiconductor parts were plated, respectively, and the discoloration was investigated and the characteristics near the melt were evaluated.
Further, the present invention is not limited to these examples, and the composition and conditions can be arbitrarily changed according to the purpose.
For the baths shown in “Examples 1 to 6” above, 4.0 μm plating was applied to the connectors and semiconductor components at a current density of 8.0 A / dm ² . Then, Bi content, glossiness, 270 ° C / 30sec discoloration survey, and 270 ° C / 30sec / 6 melt survey were performed on the obtained plating film.

Next, as the bath stability, the plating bath was visually checked for turbidity of the bath and the presence or absence of precipitation immediately after standing and after standing for 7 days. The results are shown in “Table 2”.

"Comparative example"
A comparative example is shown below. The Sn—Bi alloy plating bath having the composition described in “Table 3” was prepared, and the connector parts and the semiconductor parts were plated, respectively, and the discoloration was investigated and the characteristics near the melt were evaluated. The results are shown in “Table 3”.
The plating bath in “Table 3” above is a commercially available bath, so the details of the components are unknown.
Further, 4.0 μm plating was applied to the connector parts and the semiconductor parts at a current density of 8.0 A / dm ² with respect to the baths shown in “Comparative Examples 1 and 2”. The Bi plating content, glossiness, 270 ° C / 30sec discoloration survey, and 270 ° C / 30sec / 6 melt survey were conducted on the resulting plated coating. Also, as the bath stability of the plating bath, the turbidity of the bath and the presence or absence of precipitation were visually confirmed immediately after the bathing and after standing for 7 days. The results are shown in “Table 4”.
The plating film obtained in the above “Example” obtained the same or better results than the “Comparative Example” in any characteristic condition.

[Specific Example of Manufacturing Process] The plating of the connector part having the above-described configuration is performed in the following process sequence.
(1) Alkaline degreasing (10-30 sec) → (2) Electrolytic degreasing (2-6 A / dm ² , 10-30 sec) → (3)
Pickling (10-30 sec) → (4) Ni plating (2-6A / dm ² ) → (5) Pickling (10-30 sec) → (6) Bright Sn-Bi alloy plating (6.0-12.0A) / Dm ² ) → (7) Post-treatment (10-30 sec) → (8) Drying (There is a water washing step between each step)

Next, the plating of semiconductor components is performed in the following process sequence.
(1) Alkaline degreasing (10-30 sec) → (2) (+) Electrolytic degreasing (2-6 A / dm ² , 10-30 sec) → (3) (−) Electrolytic degreasing (2-6 A / dm ² , 10 30 sec) → (4) Acid immersion (10-30 sec) → (5) Etching → (6) Bright Sn—Bi alloy plating (6.0-12.0 A / dm ² ) → (7) Neutralization treatment (10 30sec) → (8) Post-treatment (10-30sec) → (9) Drying (with water washing process between each process)

The present invention can be applied to other electronic components such as semiconductors in addition to connector components.

Claims (4)

Gloss Sn-Bi plating having Sn of 99.9 to 95.0%, Bi of 0.1 to 5.0% and glossiness of 0.8 or more is 2.0 μm or more in thickness A bright tin / bismuth alloy plating film for electronic parts such as connectors or semiconductor parts, characterized in that it does not cause aggregation or discoloration under reflow conditions of 230 ° C. to 300 ° C. Gloss Sn-Bi plating containing Bi of 0.1 to 5.0% with respect to Sn 99.9 to 95.0% and having a glossiness of 0.8 or more is applied to a thickness of 2.0 μm or more. A bright tin / bismuth alloy plating film for electronic parts such as connectors or semiconductor parts, wherein aggregation and plating discoloration due to changes over time in a room temperature state are prevented. The amount of the first brightener added to the Sn-Bi plating solution is 0.01 mg / L or less, and it is used to apply bright Sn-Bi plating. Aggregation and discoloration of plating under reflow conditions of 230 ° C to 300 ° C A bright tin / bismuth alloy plating bath for electronic parts such as connectors or semiconductor parts, which is characterized in that no generation of the above occurs. The amount of the first brightener added to the Sn-Bi plating solution is 0.01 mg / L or less. By using this, the bright Sn-Bi plating is performed, and aggregation and plating discoloration due to changes over time at room temperature occur. A bright tin / bismuth alloy plating bath for electronic parts such as connectors or semiconductor parts, characterized in that it is not provided.