JP5979615B2 - Manufacturing method of plating material - Google Patents

Description

  The present invention relates to a plating material and a manufacturing method thereof, and more specifically, between a base plating layer provided on a conductive substrate such as Cu (copper) and a surface plating layer made of Sn (tin) or an Sn alloy. The present invention relates to a plating material in which the growth rate of an alloy layer (intermetallic compound layer) to be formed is slow and a method for producing the same.

  A material in which a plating layer (Sn plating layer) made of Sn or Sn alloy is provided on the surface of a conductive substrate made of Cu or Cu alloy is a material having excellent conductivity and strength of the substrate and excellent electric power of the Sn plating layer. It is known as a high-performance conductor having both contact characteristics, corrosion resistance, and solderability (solder wettability), and is widely used for various terminals and connectors.

  In the production of such Sn plating material, when the Sn plating layer is provided directly on the base material, the thickness of the plating layer decreases as Sn and the base metal alloy and grow with the passage of time. To do. As the thickness of the plating layer is reduced, the required performance such as solder wettability is lowered, which may cause product defects. Therefore, conventionally, Cu or Ni (nickel) is used on the base material for the purpose of preventing the Sn plating layer surface from being smooth (appearance) and preventing the diffusion of zinc to the surface when the base material is brass. ), An Sn plating layer is provided thereon, and heat treatment called reflow is performed for the purpose of whisker suppression and long-term storage (alloying suppression) in the Sn plating layer.

  Due to the reflow treatment, a thin alloy layer is formed between the base plating layer and the Sn plating layer, and this alloy layer has a slower growth rate than a naturally formed alloy layer that does not depend on the reflow treatment. It is considered that it can be suppressed and is advantageous in maintaining solder wettability (Patent Documents 7 and 8).

  However, even with such a reflow process, the alloy layer gradually grows and thickens over time, and the thickness of the Sn plating layer and the base plating layer is reduced, so that the solder wettability and insertion / removability are reduced. In order to maintain the thickness of the Sn plating layer over a long period of time and suppress the decrease in solder wettability, it has not been sufficient yet.

  For this reason, the alloying of Sn and the base plating metal and the growth rate of the alloy layer are made slower, and the thickness of the Sn plating layer is maintained over a long period of time, thereby suppressing the decrease in solder wettability. Various techniques as described below have been studied and proposed.

  That is, in Patent Document 1, a base plating layer made of a metal or an alloy thereof included in Groups 4 to 9 of the periodic table is formed on the surface of a conductive substrate, and then an intermediate plating made of Cu or a Cu alloy. A technique for slowing alloying between the Sn plating layer and the base material or the base plating layer even in a high-temperature environment by sequentially forming a layer, a surface plating layer made of Sn or Sn alloy is disclosed.

  Moreover, in patent document 2, after forming each layer by the structure similar to patent document 1, an intermediate plating layer is lose | disappeared by heat processing etc., and forming the layer which consists of a Sn-Cu intermetallic compound, A technique for slowing the diffusion reaction between the Sn plating layer and the base material or the base plating layer even in a high temperature environment is disclosed.

  Further, in Patent Document 3, when a layer made of Ni or Ni alloy is formed between a base plating layer made of Cu or Cu alloy and an Sn plating layer, the Ni or Ni alloy layer and the Sn plating layer One or more diffusion layers mainly composed of Cu and Sn or Cu, Ni and Sn are formed between the diffusion layers in contact with the Sn plating layer, and the thickness and the contents of Cu and Ni. A technique for maintaining solder wettability and other characteristics by controlling the above is disclosed.

  Further, in Patent Document 4, a base plating layer made of any one of Fe or Fe alloy, Ni or Ni alloy, Co or Co alloy is formed on the surface of the conductive substrate, and then Sn or Sn alloy is formed. By sequentially forming a first intermediate plating layer made of Cu, a second intermediate plating layer made of Cu or Cu alloy, and a surface plating layer made of Sn or Sn alloy, the Sn plating layer, the base material, and the base plating are formed even in a high temperature environment. Techniques for slowing the diffusion reaction between layers are disclosed.

  Further, Patent Documents 5 and 6 show that solder wettability is reduced by providing an Sn plating layer after performing an alloy plating containing phosphorus and Cu as an intermediate layer on a Cu or Cu alloy base material. A technique for improving heat resistance and insertion / removability (ease of insertion / removal when using a plating material) is disclosed.

  However, these technologies are not the usual two-layer plating composed of a base plating layer and a surface Sn plating layer, but a single plating layer made of another metal is added, and further heating is performed thereon. Etc. are applied. Alternatively, after forming an intermediate layer having a complicated composition, a diffusion layer is formed between the intermediate layer and the surface layer by heat treatment.

  For this reason, in these techniques, it is necessary to increase processes, such as plating and heat processing, and processing time increases. In addition, management items for the added plating layer and diffusion layer, for example, the management of the thickness of the plating layer, and the like increase. As a result, these increase the cost of the product.

JP 2008-223143 A JP 2005-344188 A JP 2003-293187 A JP 2003-318157 A JP 2001-169995 A JP 2001-16996 A JP-A-4-235292 JP-A-4-329891

  In view of the above problems, the present invention reduces the alloying rate of Sn and the base plating metal and the growth rate of the alloy layer more slowly than before without increasing the manufacturing cost, thereby reducing the thickness of the Sn plating layer. It is an object of the present invention to provide a method for producing an Sn plating material that can be maintained over a long period of time and can suppress a decrease in solder wettability of the plating material.

  In order to solve the above-mentioned problems, the present inventor conducted various experiments and intensively studied. As a result, the reflow process that has been conventionally performed in the process of manufacturing the plating material is more strongly performed than the conventional plating. It has been found that even with a two-layer plating composed of a layer and a surface Sn plating layer, the alloying of Sn and the underlying plating metal and the growth rate of the alloy layer can be significantly slowed compared to the prior art. It came to complete. This will be described in detail below.

  As described above, conventionally, in the production process of the plating material, the reflow treatment has been performed as the heat treatment for suppressing the formation of whiskers in the Sn plating layer. However, the reflow treatment suppresses the formation of whiskers. It was generally considered that it was preferable to perform the process within a range so that the alloy layer was not formed thick.

  However, as a result of experiments by the present inventors, it has been found that as the thickness of the alloy layer formed in the reflow process increases, the growth rate of the alloy layer with the passage of time thereafter decreases.

  Therefore, contrary to the conventional idea, the present inventor suppresses the growth of the alloy layer over time by forming a thicker alloy layer by performing a reflow treatment stronger than before, resulting in a result. In addition, the thickness of the Sn plating layer can be maintained at a constant thickness over a long period of time, while the reduction of the thickness of the Sn plating layer and the base plating layer by forming a thick alloy layer, It has been thought that if each plating layer is provided thick in anticipation of these weight reductions, the solder wettability and insertion / extraction properties will not be adversely affected.

  Then, in accordance with the above concept, the thickness of the Sn plating layer is maintained over a long period of time, and specific Sn plating layer, base plating layer, and alloy that do not cause deterioration of solder wettability and insertion / extraction property Various experiments and studies were conducted on the layer thickness.

  As a result, the growth rate of the alloy layer is not only closely related to the thickness of the alloy layer, but also closely related to the average particle diameter of the alloy formed, and is specifically shown in the following technologies. In the case of a plating material, even if the plating material has a two-layer structure composed of a base plating layer and a surface Sn plating layer, the alloying of Sn and the base plating metal and the growth rate of the alloy layer are greatly reduced. The present inventors have found that the thickness of the Sn plating layer can be maintained over a long period of time, and that deterioration of solder wettability and insertability of the plating material can be suppressed, and the present invention has been completed.

  And since this invention can use the conventional reflow equipment as it is only by changing heating conditions, it does not cause an increase in manufacturing cost.

  The first to twelfth techniques related to the present invention will be described below. Among the technologies shown below, the first to sixth technologies employ a base plating layer made of Cu or Cu alloy, and the seventh to twelfth technologies employ a base plating layer made of Ni or Ni alloy. Technology.

The first technique related to the present invention is:
A base plating layer made of Cu or Cu alloy is formed on a base material made of Cu or Cu alloy, and a surface plating layer made of Sn or Sn alloy is further formed, and the base plating layer is further subjected to heat treatment. And a plating material in which an alloy layer of Cu and Sn is formed between the surface plating layer, and the thickness of the base plating layer is 0.5 to 2.0 μm,
The surface plating layer has a thickness of 0.5 to 3.0 μm,
The Cu and Sn alloy layer has a thickness of 0.8 to 2.0 μm,
Furthermore, the average particle diameter of the alloy which forms the said alloy layer of Cu and Sn is a plating material characterized by 4-10 micrometers.

  As a result of the experiment based on the above-mentioned concept, a plating material having a base plating layer having a thickness of 0.5 to 2.0 μm provided on a substrate and further having a surface plating layer having a thickness of 0.5 to 3.0 μm is heated. The plating material on which the alloy layer having a thickness of 0.8 to 2.0 μm and an average particle diameter of 4 to 10 μm is formed by processing is a plating material having a two-layer structure composed of a base plating layer and a surface Sn plating layer However, the alloying of Sn and the underlying plating metal and the growth rate of the alloy layer are slower than before, the thickness of the Sn plating layer can be maintained over a long period of time, and the solder wettability and insertability of the plating material can be maintained. It was found that the decrease was suppressed.

The second technique related to the present invention is:
A base plating layer made of Cu or Cu alloy is formed on a base material made of Cu or Cu alloy, and a surface plating layer made of Sn or Sn alloy is further formed, and the base plating layer is further subjected to heat treatment. And a plating material in which an alloy layer of Cu and Sn is formed between the surface plating layer, and the thickness of the base plating layer is 0.5 to 2.0 μm,
The surface plating layer has a thickness of 0.5 to 3.0 μm,
The average particle size of the alloy forming the alloy layer of Cu and Sn is 4 to 10 μm,
Further, the plating material is characterized in that a growth rate of the Cu and Sn alloy layer at 150 ° C. is 0.2 μm / √day or less.

  A plating material provided with a base plating layer having a thickness of 0.5 to 2.0 μm on the substrate and further provided with a surface plating layer having a thickness of 0.5 to 3.0 μm is heat-treated, and an average particle size of 4 to The plating material on which the 10 μm alloy layer is formed is a plating material having a two-layer structure in which the growth rate of the alloy layer at 150 ° C. is 0.2 μm / √day or less, and is composed of a base plating layer and a surface Sn plating layer. However, the alloying rate of Sn and the base plating metal and the growth rate of the alloy layer are slower than before, the thickness of the Sn plating layer can be maintained over a long period of time, and the solder wettability and insertability of the plating material are reduced. It is suppressed.

The third technique related to the present invention is:
A base plating layer made of Cu or Cu alloy is formed on a base material made of Cu or Cu alloy, and a surface plating layer made of Sn or Sn alloy is further formed, and the base plating layer is further subjected to heat treatment. And a plating material in which an alloy layer of Cu and Sn is formed between the surface plating layer, and the thickness of the base plating layer is 0.5 to 2.0 μm,
The surface plating layer has a thickness of 0.5 to 3.0 μm,
The heat treatment is a plating material characterized in that the heat treatment is performed in a temperature atmosphere of 230 to 400 ° C. for 30 to 180 seconds.

  A plating material provided with a base plating layer having a thickness of 0.5 to 2.0 μm on a substrate and further having a surface plating layer having a thickness of 0.5 to 3.0 μm is placed in a temperature atmosphere of 230 to 400 ° C. The plating material formed by performing the heat treatment for up to 180 seconds has a slower alloying rate between Sn and the base plating metal and the growth rate of the alloy layer than before, and the thickness of the Sn plating layer over a long period of time. And the decrease in solder wettability and insertability of the plating material is suppressed.

The fourth technique related to the present invention is:
On the base material made of Cu or Cu alloy, a base plating layer made of Cu or Cu alloy having a thickness of 0.5 to 2.0 μm is formed,
After forming a surface plating layer made of Sn or Sn alloy having a thickness of 0.5 to 3.0 μm on the base plating layer,
Furthermore, it is a method for producing a plating material, characterized in that a heat treatment is performed for 30 to 180 seconds in a temperature atmosphere of 230 to 400 ° C., and an alloy layer is formed between the base plating layer and the surface plating layer. .

  A base plating layer having a thickness of 0.5 to 2.0 μm is provided on the base material, and further a surface plating layer having a thickness of 0.5 to 3.0 μm is provided, and then a temperature atmosphere of 230 to 400 ° C. is applied to 30 to 180 ° C. The plating material formed by heat treatment for 2 seconds keeps the Sn plating layer thickness over a long period of time, with the alloying of Sn and the underlying plating metal and the growth rate of the alloy layer being slower than before. It is possible to suppress a decrease in solder wettability and insertability of the plating material.

The fifth technique related to the present invention is:
On the base material made of Cu or Cu alloy, a base plating layer made of Cu or Cu alloy having a thickness of 0.5 to 2.0 μm is formed,
After forming a surface plating layer made of Sn or Sn alloy having a thickness of 0.5 to 3.0 μm on the base plating layer,
Further, a heat treatment is performed for 30 to 180 seconds in a temperature atmosphere of 230 to 400 ° C., and the thickness is made of an alloy of Cu and Sn having an average particle diameter of 4 to 10 μm between the base plating layer and the surface plating layer. It is a manufacturing method of the plating material characterized by forming an alloy layer of 0.8-2.0 micrometers.

  A base plating layer having a thickness of 0.5 to 2.0 μm is provided on the base material, and further a surface plating layer having a thickness of 0.5 to 3.0 μm is provided, and then a temperature atmosphere of 230 to 400 ° C. is applied to 30 to 180 ° C. The plating material in which an alloy layer having a thickness of 0.8 to 2.0 μm and an average particle diameter of 4 to 10 μm is formed by performing a heat treatment for 2 seconds is used for alloying of Sn and a base plating metal or an alloy layer. The growth rate is slower than before, the thickness of the Sn plating layer can be maintained over a long period of time, and the decrease in solder wettability and insertability of the plating material is suppressed.

The sixth technique related to the present invention is:
On the base material made of Cu or Cu alloy, a base plating layer made of Cu or Cu alloy having a thickness of 0.5 to 2.0 μm is formed,
After forming a surface plating layer made of Sn or Sn alloy having a thickness of 0.5 to 3.0 μm on the base plating layer,
Further, heat treatment is performed for 30 to 180 seconds in a temperature atmosphere of 230 to 400 ° C., and an alloy of Cu and Sn having an average particle diameter of 4 to 10 μm is formed between the base plating layer and the surface plating layer. It is a method for producing a plating material, characterized in that an alloy layer having a growth rate of 0.2 μm / √day or less at 0 ° C. is formed.

  A base plating layer having a thickness of 0.5 to 2.0 μm is provided on the base material, and further a surface plating layer having a thickness of 0.5 to 3.0 μm is provided, and then a temperature atmosphere of 230 to 400 ° C. is applied to 30 to 180 ° C. The plating material on which the alloy layer having an average particle diameter of 4 to 10 μm is formed by performing the heat treatment for 2 seconds, the growth rate of the alloy layer at 150 ° C. is 0.2 μm / √day or less, and Sn and the base plating metal And the growth rate of the alloy layer are slower than before, the thickness of the Sn plating layer can be maintained over a long period of time, and the decrease in solder wettability and insertability of the plating material is suppressed.

  In the first to sixth techniques, preferable ranges are 0.8 to 1.2 μm for the thickness of the base plating layer, 1.0 to 2.5 μm for the thickness of the surface plating layer, and Cu and Sn. The thickness of the alloy layer is 0.9 to 1.2 μm, and the average particle size of the alloy of Cu and Sn is 5 to 8 μm. Moreover, about heat processing, the heat processing hold | maintained for 60 to 120 second in a 260-320 degreeC temperature atmosphere is preferable.

  The present inventor further conducted an experiment on a base plating layer made of Ni or a Ni alloy according to the same concept as described above, and obtained preferable conditions. Each technique shown below is a technique in the case of Ni or Ni alloy base corresponding to the above first to sixth techniques.

That is, the seventh technique related to the present invention is:
A base plating layer made of Ni or Ni alloy is formed on a base material made of Cu or Cu alloy, and a surface plating layer made of Sn or Sn alloy is further formed, and the base plating layer is further subjected to heat treatment. And a plating material in which an alloy layer of Ni and Sn is formed between the surface plating layer, and the thickness of the base plating layer is 0.5 to 2.0 μm,
The surface plating layer has a thickness of 0.5 to 3.0 μm,
The thickness of the alloy layer of Ni and Sn is 0.5 to 2.0 μm,
Furthermore, the average particle diameter of the alloy forming the alloy layer of Ni and Sn is 0.6 to 1.2 μm.

The eighth technique related to the present invention is:
A base plating layer made of Ni or Ni alloy is formed on a base material made of Cu or Cu alloy, and a surface plating layer made of Sn or Sn alloy is further formed, and the base plating layer is further subjected to heat treatment. And a plating material in which an alloy layer of Ni and Sn is formed between the surface plating layer, and the thickness of the base plating layer is 0.5 to 2.0 μm,
The surface plating layer has a thickness of 0.5 to 3.0 μm,
The average particle diameter of the alloy forming the alloy layer of Ni and Sn is 0.6 to 1.2 μm,
Furthermore, the plating material is characterized in that the growth rate of the alloy layer of Ni and Sn at 150 ° C. is 0.2 μm / √day or less.

The ninth technique related to the present invention is:
A base plating layer made of Ni or Ni alloy is formed on a base material made of Cu or Cu alloy, and a surface plating layer made of Sn or Sn alloy is further formed, and the base plating layer is further subjected to heat treatment. And a plating material in which an alloy layer of Ni and Sn is formed between the surface plating layer, and the thickness of the base plating layer is 0.5 to 2.0 μm,
The surface plating layer has a thickness of 0.5 to 3.0 μm,
The heat treatment is a plating material characterized in that the heat treatment is performed in a temperature atmosphere of 230 to 400 ° C. for 30 to 180 seconds.

The tenth technique related to the present invention is:
On the base material made of Cu or Cu alloy, a base plating layer made of Ni or Ni alloy having a thickness of 0.5 to 2.0 μm is formed,
After forming a surface plating layer made of Sn or Sn alloy having a thickness of 0.5 to 3.0 μm on the base plating layer,
Furthermore, it is a method for producing a plating material, characterized in that a heat treatment is performed for 30 to 180 seconds in a temperature atmosphere of 230 to 400 ° C., and an alloy layer is formed between the base plating layer and the surface plating layer. .

The eleventh technology related to the present invention is:
On the base material made of Cu or Cu alloy, a base plating layer made of Ni or Ni alloy having a thickness of 0.5 to 2.0 μm is formed,
After forming a surface plating layer made of Sn or Sn alloy having a thickness of 0.5 to 3.0 μm on the base plating layer,
Furthermore, a heat treatment is performed for 30 to 180 seconds in a temperature atmosphere of 230 to 400 ° C., and an alloy of Ni and Sn having an average particle diameter of 0.6 to 1.2 μm is provided between the base plating layer and the surface plating layer. An alloy layer having a thickness of 0.5 to 2.0 μm is formed.

The twelfth technique related to the present invention is:
On the base material made of Cu or Cu alloy, a base plating layer made of Ni or Ni alloy having a thickness of 0.5 to 2.0 μm is formed,
After forming a surface plating layer made of Sn or Sn alloy having a thickness of 0.5 to 3.0 μm on the base plating layer,
Furthermore, a heat treatment is performed for 30 to 180 seconds in a temperature atmosphere of 230 to 400 ° C., and an alloy of Ni and Sn having an average particle diameter of 0.6 to 1.2 μm is provided between the base plating layer and the surface plating layer. And an alloy layer having a growth rate at 150 ° C. of 0.2 μm / √day or less is formed.

  In the seventh to twelfth techniques, preferable ranges are 1.0 to 1.3 μm for the thickness of the base plating layer, 1.0 to 2.5 μm for the thickness of the surface plating layer, and Ni and Sn. The thickness of the alloy layer is 0.7 to 1.0 μm, and the average particle size of the alloy of Ni and Sn is 0.6 to 0.8 μm. Moreover, about heat processing, the heat processing hold | maintained for 60 to 120 second in a 260-320 degreeC temperature atmosphere is preferable.

The present invention has been made on the basis of the above-described technologies, and the invention according to claim 1
On the base material made of Cu or Cu alloy, a base plating layer made of Cu or Cu alloy having a thickness of 0.8 to 1.2 μm is formed,
After forming a surface plating layer made of Sn or Sn alloy having a thickness of 2.0 to 3.0 μm on the base plating layer,
Furthermore, it is a method for producing a plating material, characterized in that heat treatment is performed for 60 to 120 seconds in a temperature atmosphere of 260 to 320 ° C., and an alloy layer is formed between the base plating layer and the surface plating layer. .

The invention according to claim 2
On the base material made of Cu or Cu alloy, a base plating layer made of Cu or Cu alloy having a thickness of 0.8 to 1.2 μm is formed,
After forming a surface plating layer made of Sn or Sn alloy having a thickness of 2.0 to 3.0 μm on the base plating layer,
Furthermore, a heat treatment is performed for 60 to 120 seconds in a temperature atmosphere of 260 to 320 ° C., and the thickness is made of an alloy of Cu and Sn having an average particle diameter of 5 to 8 μm between the base plating layer and the surface plating layer. It is a manufacturing method of the plating material characterized by forming an alloy layer of 0.9 to 1.2 μm.

The invention according to claim 3
On the base material made of Cu or Cu alloy, a base plating layer made of Cu or Cu alloy having a thickness of 0.8 to 1.2 μm is formed,
After forming a surface plating layer made of Sn or Sn alloy having a thickness of 2.0 to 3.0 μm on the base plating layer,
Further, heat treatment is performed for 60 to 120 seconds in a temperature atmosphere of 260 to 320 ° C., and an alloy of Cu and Sn having an average particle diameter of 5 to 8 μm is formed between the base plating layer and the surface plating layer. It is a method for producing a plating material, characterized in that an alloy layer having a growth rate of 0.2 μm / √day or less at 0 ° C. is formed.

  In addition, the numerical range regarding the thickness of the base plating layer and the surface plating layer in the present invention is specified in consideration of practicality, and is adjusted according to the required use, and accordingly, the thickness of the alloy layer is adjusted. The average particle diameter is also adjusted.

  According to the present invention, the thickness of the Sn plating layer can be maintained over a long period of time without causing an increase in manufacturing cost by lowering the alloying rate between the Sn and the base plating metal and the growth rate of the alloy layer. And the manufacturing method of Sn plating material which can suppress the fall of the solder wettability of plating material can be provided.

2 is a sectional view conceptually showing the layer structure of a test piece of Example 1. FIG. It is a figure which shows the relationship between the elapsed time of Example 1, and comparative samples 1-4, and the thickness which the Cu-Sn alloy layer grew. 4 is a SEM photograph of a Ni—Sn alloy layer in Example 2 and Comparative Sample 6. It is a figure which shows the relationship between the elapsed time of Example 2, the comparative samples 5 and 6, and the thickness which the Ni-Sn alloy layer grew.

  Hereinafter, the present invention will be described based on embodiments. Note that the present invention is not limited to the following embodiments. Various modifications can be made to the following embodiments within the same and equivalent scope as the present invention.

[1] Example in which Sn plating was applied to a copper alloy substrate after Cu base plating. Preparation of Sn plating test piece (Example 1)
(1) Base material and plating Cu base plating with a thickness of 0.8 to 1.2 μm was applied to a base material made of brass, and then matte Sn plating with a thickness of 2 to 3 μm was applied thereon.

(2) Reflow treatment Next, a strong reflow treatment was performed in which the matte-plated test piece was heated at a heating temperature of 260 ° C. for 60 seconds using an infrared image furnace to obtain Example 1.

  For reference, the layer structure of the test piece prepared as described above is shown. 1 is a cross-sectional view conceptually showing the layer structure of the test piece of Example 1. FIG. In FIG. 1, 10 is a base material, 20 is a Cu base plating layer, 40 is a matte Sn plating layer, and 24 is a Cu-Sn alloy layer.

(Comparative example)
(1) Comparative Example 1
Comparative Example 1 (Comparative Sample 1) is a commercially available product in which a matte Sn plating with a thickness of about 1.2 μm is applied on a base material made of brass to which a Cu base plating is applied, and further subjected to a conventional reflow treatment. It was.

(2) Comparative Example 2
Comparative Example 2 (comparative example) is a commercially available product in which a matte Sn plating with a thickness of about 1.3 μm is applied on a substrate made of a Corson copper alloy to which a Cu base plating is applied, and further subjected to a conventional reflow treatment. Sample 2).

(3) Comparative Example 3
Comparative example 3 (comparative sample 3) and a commercially available product in which matte Sn having a thickness of about 1.1 μm was applied on a base material made of brass subjected to Cu base plating and further subjected to a conventional reflow treatment were used. did.

(4) Comparative Example 4
Three-layer reflow in which matte Sn plating with a thickness of 1 to 3 μm is applied on a brass base material that has been subjected to Ni base plating and Cu base plating in order from the base material side, and further subjected to conventional reflow processing A commercially available plating product was used as Comparative Example 4 (Comparative Sample 4).

2. Measurement of thickness and average particle diameter of alloy layer after reflow treatment Measuring method a. Alloy Layer Thickness The alloy layer thickness was measured with a fluorescent X-ray film thickness meter.

b. Average particle diameter Each of Example 1 and Comparative Examples 1 to 4 was immersed in an alkaline aqueous solution containing p-nitrophenol to peel off the Sn plating layer to expose the surface of the alloy layer. The exposed surface of each alloy layer was observed with a scanning electron microscope (SEM) at a magnification of 1000 to 10000 to obtain SEM photographs of alloy layer particles. The obtained SEM photograph was analyzed with particle analysis software “Quick Grain” (manufactured by Innotech) to determine the average particle size.

B. Measurement Results Table 1 summarizes the measurement results of Example 1 and Comparative Examples 1 to 4.

  From Table 1, in Example 1 in which the strong reflow treatment was performed, an alloy layer having a sufficient thickness was formed as compared with Comparative Examples (comparative samples) 1 to 3 in which the conventional reflow treatment was performed. It can be seen that the particle size is also sufficiently large. In addition, about the comparative example 4, since it is a 3 layer reflow process goods and the structure of a plating layer differs from others, the measurement of an average particle diameter is not performed.

3. Growth rate of Cu-Sn alloy layer a. Measuring method The growth rate of the Cu-Sn alloy layer was measured by an acceleration test under heating to 150 ° C. Example 1 and Comparative Examples 1 to 4 were placed in a thermostatic bath at 150 ° C., and the growth amount of the thickness of the alloy layer was measured until 120 hours passed.

B. Measurement results The measurement results are shown in FIG. FIG. 2 is a graph showing the relationship between the elapsed time of Example 1 and Comparative Examples 1 to 4 and the grown thickness of the Cu—Sn alloy layer, and the horizontal axis is the square root (√ days) of the elapsed time. Is the grown thickness (μm) of the alloy layer.

  From FIG. 2, the growth rate of the alloy layer in Example 1 is about 0.12 μm / √day from the slope of the straight line, and it is Sn compared with Comparative Examples (Comparative Samples) 1 to 3 subjected to the conventional reflow treatment. It can be seen that the growth rate of the alloy layer of the plating and the metal of the base plating layer is slow.

  Moreover, in the case of the comparative example (comparative sample) 4, since the Ni layer is provided immediately above the base material, the diffusion of Cu derived from the base material is suppressed at the time of reflowing and thereafter, so that it has a great effect on deterioration over time. Although the growth rate of the alloy layer of Example 1 is slower than that of Comparative Example 4, it can be seen that there is a greater effect on deterioration with time than that of Comparative Example 4.

  As described above, in Example 1, the great effect for suppressing the growth of the alloy layer is that the alloy layer grows by grain boundary diffusion, but by performing a strong reflow treatment to thicken the alloy layer, It is presumed that the number of grain boundaries is reduced, the number of paths through which Sn and Cu diffuse is reduced, and the growth of the alloy layer is suppressed.

4). Relationship between thickness of Cu—Sn alloy layer and average particle diameter and growth rate From the measurement results of Example 1 and Comparative Examples 1 to 3 in Table 1 and FIG. In the Sn alloy layer system, it can be seen that the strength of reflow heating, that is, the thickness of the alloy layer corresponds to the average particle size, and also corresponds to the suppression of the growth rate.

  That is, as the alloy layer becomes thicker, the average particle diameter of the alloy layer also increases, and the growth rate of the alloy layer is further suppressed.

[2] Example in which Sn plating was applied to a copper alloy base material after Ni base plating. Preparation of Sn plating test piece (Example 2)
(1) Base material and plating Ni base plating with a thickness of 1 to 1.3 μm was applied to a brass base material, and then matte Sn plating with a thickness of 2 μm was applied thereon.

(2) Reflow process Next, the strong reflow process was performed by the same method as Example 1. FIG.

(Comparative example)
(1) Comparative Example 5
Commercially available substrate with a non-glossy Sn plating with a thickness of 2 to 2.5 μm and a conventional reflow treatment on a Corson copper alloy base material with a Ni base plating with a thickness of 1 to 2 μm The product was designated as Comparative Example 5 (Comparative Sample 5).

(2) Comparative Example 6
Comparative Example 6 is a commercially available product in which matte Sn plating with a thickness of 1 to 3 μm is applied on a brass base material with a Ni base plating with a thickness of 1 to 2 μm and further subjected to a conventional reflow treatment. (Comparative sample 6).

2. Measurement of thickness of alloy layer after reflow treatment Measurement Method The thickness of the alloy layer was measured by the same method as in Example 1.

B. Measurement Results Table 2 summarizes the measurement results of Example 2 and Comparative Examples 5 and 6.

  From Table 2, it can be seen that in Example 2 where the strong reflow treatment was performed, an alloy layer having a sufficient thickness was formed as compared with Comparative Examples 5 and 6 where the conventional reflow treatment was performed. .

3. Average particle diameter of Ni—Sn alloy layer As for the average particle diameter of the alloy layer, SEM photographs of alloy layer particles were obtained by the same method as in Example 1. Because of the small size, analysis by particle analysis software as in Example 1 was not possible, and the dimensions were read from the photograph.

  Specifically, for Example 2 and Comparative Example 6, SEM photographs of the respective alloy layers were taken, and the average particle diameter was read from the photographs. The obtained SEM photograph is shown in FIG. 3A is an SEM photograph based on Example 2, and FIG. 3B is an SEM photograph based on Comparative Example 6. In FIG.

  From the photograph shown in FIG. 3, the average particle size in Example 2 where the growth rate of the alloy layer is slow is about 1 μm, and the average particle size in Comparative Example 6 where the growth rate of the alloy layer is fast is 0.4 μm or less. I understood.

4). Growth rate of Ni—Sn alloy layer a. Measurement Method The growth rate of the Ni—Sn alloy layer was measured by the same method as in Example 1.

B. Measurement results The measurement results are shown in FIG. FIG. 4 is a graph showing the relationship between the elapsed time and the grown thickness of the Ni—Sn alloy layer in Example 2 and Comparative Examples 5 and 6, that is, in the case of Ni base plating.

  From FIG. 4, also in the case of Ni undercoating, the test piece of Example 2 subjected to the strong reflow treatment was compared with the Sn plating and the metal of the undercoating layer as compared with Comparative Examples 5 and 6 subjected to the conventional reflow treatment. It can be seen that the growth rate of the alloy layer is slow.

  Then, the growth rate of the alloy layer of Example 2 in the accelerated test at 150 ° C. is about 0.2 μm / √day from the slope of the straight line in FIG. 4, and is not higher than the growth rate necessary for maintaining sufficient solder wettability. It can be seen that it is suppressed.

5. Relationship between Ni—Sn Alloy Layer Thickness, Average Particle Diameter, and Growth Rate As described above, in the case of a Cu underlayer, the strength of reflow heating, that is, the alloy layer, is within the same Cu—Sn alloy layer system. The thickness corresponds to the average particle size, and also corresponds to the suppression of the growth rate.

  Similarly, even in the case of Ni base, from the measurement results of Example 2 and Comparative Example 6 (Comparative Sample 6) in Table 2 and FIGS. It can be seen that the strength of the reflow heating, that is, the thickness of the alloy layer corresponds to the average particle size, and also corresponds to the suppression of the growth rate.

[3] Solder wettability It is known that solder wettability is good when the layer of only Sn that is not alloyed is 0.3 μm or more. For this reason, in Example 1 which has a Sn plating layer having a thickness of 2 to 3 μm and the growth rate of the alloy layer is as low as 0.12 μm / √day, the thickness of the Sn plating layer is set to 0. It can be maintained at 3 μm or more, and it is expected that good solder wettability can be exhibited.

  Similarly, in the case of Example 2 which has a Sn plating layer having a thickness of 2 μm and the growth rate of the alloy layer is as low as 0.2 μm / √day, the thickness of the Sn plating layer is set to 0. Since it can be maintained at 3 μm or more, it is expected that good solder wettability can be exhibited.

[4] Example of performing Cu base plating and changing reflow conditions In the following, after the Cu base plating with a thickness of 0.8 to 1.2 μm on the surface of a brass base material, After the surface plating of 3 μm of Sn, reflow treatment is performed under various conditions for the heating temperature and the heating time, and the thickness and average particle diameter of the alloy layer are measured.

(1) Preparation of sample The reflow process was performed with the heating temperature (degreeC) and heating time (second) which are shown in Table 3, and the sample of Example 3 and Comparative Examples 7-11 was produced.

(2) Measurement of alloy layer thickness and average particle size By the same method as in Example 1, the thickness and average particle size of the alloy layer of each sample were measured. Table 3 shows the measurement results.

  As shown in Table 3, in the case of Cu base plating, when a strong reflow treatment was performed at a heating temperature of 260 ° C. and a heating time of 60 seconds (Example 3), an alloy having a thickness of 1.05 μm and an average particle size of 5.49 μm A layer is formed. On the other hand, in each comparative example, since it is a normal reflow process, both the thickness and the average particle diameter are smaller than those in Example 3.

  As described above, in the system of Cu-Sn alloy layers with the same type of alloy layer, the strength of reflow heating, that is, the thickness of the alloy layer corresponds to the average particle size, and further suppresses the growth rate. Both correspond. For this reason, it can be predicted that the growth of the alloy layer can be sufficiently suppressed in the case of Example 3 in which a sufficiently thick alloy layer is formed.

[5] Example of performing Ni base plating and changing reflow conditions In the following, after Ni base plating with a thickness of 1 to 1.3 μm on the surface of a brass base material, with a thickness of 1 to 3 μm After the surface plating of Sn, the reflow treatment is performed under various conditions for the heating temperature and the heating time, and the thickness of the alloy layer is measured.

(1) Preparation of sample The reflow process was performed with the heating temperature (degreeC) and heating time (second) which are shown in Table 4, and the sample of Example 4 and Comparative Examples 12 and 13 was produced.

(2) Measurement of alloy layer thickness By the same method as Example 2, while measuring the thickness of the alloy layer of each sample, the average particle diameter was measured about Example 4 and Comparative Example 12. Table 4 shows the measurement results.

  As shown in Table 4, in the case of Ni base plating, when a strong reflow treatment is performed at a heating temperature of 260 ° C. and a heating time of 60 seconds (Example 4), an alloy layer having a thickness of 0.69 μm and an average particle diameter of 1 μm is formed. Is formed. On the other hand, since each comparative example is a normal reflow process, both the thickness and the average particle diameter are smaller than those in Example 4.

  As described above, in the Ni-Sn alloy system in which the kind of the alloy layer is the same, the strength of the reflow heating, that is, the thickness of the alloy layer corresponds to the average particle size, and further, the growth rate is suppressed. It corresponds. For this reason, it can be predicted that the growth of the alloy layer can be sufficiently suppressed in the case of Example 4 in which the alloy layer having a sufficient thickness is formed.

  The present invention can provide a low-cost Sn-plated product with little deterioration of the Sn plating layer function over time and a technology that can prevent deterioration of the function of the plating layer of Sn-plating product with time at a low cost. It can be used in electrical and electronic industries where plating products are indispensable.

DESCRIPTION OF SYMBOLS 10 Base material 20 Cu base plating layer 24 Cu-Sn alloy layer 40 Matte Sn plating layer

Claims (3)

On the base material made of Cu or Cu alloy, a base plating layer made of Cu or Cu alloy having a thickness of 0.8 to 1.2 μm is formed,
After forming a surface plating layer made of Sn or Sn alloy having a thickness of 2.0 to 3.0 μm on the base plating layer,
Furthermore, the heat processing hold | maintained for 60 to 120 second in the temperature atmosphere of 260-320 degreeC are performed, and the alloy layer is formed between the said foundation | substrate plating layer and a surface plating layer, The manufacturing method of the plating material characterized by the above-mentioned. On the base material made of Cu or Cu alloy, a base plating layer made of Cu or Cu alloy having a thickness of 0.8 to 1.2 μm is formed,
After forming a surface plating layer made of Sn or Sn alloy having a thickness of 2.0 to 3.0 μm on the base plating layer,
Furthermore, a heat treatment is performed for 60 to 120 seconds in a temperature atmosphere of 260 to 320 ° C., and the thickness is made of an alloy of Cu and Sn having an average particle diameter of 5 to 8 μm between the base plating layer and the surface plating layer. A method for producing a plating material, comprising forming an alloy layer of 0.9 to 1.2 μm. On the base material made of Cu or Cu alloy, a base plating layer made of Cu or Cu alloy having a thickness of 0.8 to 1.2 μm is formed,
After forming a surface plating layer made of Sn or Sn alloy having a thickness of 2.0 to 3.0 μm on the base plating layer,
Further, heat treatment is performed for 60 to 120 seconds in a temperature atmosphere of 260 to 320 ° C., and an alloy of Cu and Sn having an average particle diameter of 5 to 8 μm is formed between the base plating layer and the surface plating layer. A method for producing a plating material, comprising forming an alloy layer having a growth rate of 0.2 μm / √day or less at 0 ° C.