JP4804191B2 - Cu-Zn alloy tin plating strip - Google Patents

Description

  The present invention relates to a Cu—Zn-based alloy Sn plating strip that is suitable as a conductive material for connectors, terminals, relays, switches, and the like and has good heat-resistant peelability.

  Cu-Zn alloys are widely used as electrical contact materials for connectors, terminals, relays, switches and the like because they are less expensive than phosphor bronze, beryllium copper, and Corson alloys, although they are less expensive. A typical Cu—Zn alloy is brass, and alloys such as C2600 and C2680 are defined in JIS H3100. When a Cu—Zn alloy is used as an electrical contact material, Sn plating is often applied in order to stably obtain a low contact resistance. For this reason, the Sn-plated strip of Cu—Zn-based alloy takes advantage of Sn's excellent solder wettability, corrosion resistance, and electrical connectivity, and is used for automobile electrical wiring harness terminals, printed circuit board (PCB) terminals, consumer products. It is used in large quantities for electrical and electronic parts such as connector contacts.

Usually, when the reflow Sn plating strip of a copper alloy is held at a high temperature for a long time, a phenomenon that the plating layer peels from the base material (hereinafter, thermal peeling) occurs. When Zn is added to the copper alloy, the thermal peeling property is improved. Therefore, the heat-resistant peelability of the Cu—Zn alloy is relatively good.
The Sn-plated strip of the Cu-Zn alloy is degreased and pickled, and then a base plating layer is formed by an electroplating method, then an Sn plating layer is formed by an electroplating method, and finally a reflow treatment is performed. Manufactured in the process of melting the plating layer.
As the base plating of the Cu—Zn-based alloy Sn plating strip, Cu base plating is common, and Cu / Ni two-layer base plating may be applied for applications requiring heat resistance. Here, the Cu / Ni two-layer base plating is a plating obtained by performing reflow treatment after performing electroplating in the order of Ni base plating, Cu base plating, and Sn plating. To Sn phase, Cu—Sn phase, Ni phase, and base material. Details of this technique are disclosed in Patent Documents 1 to 3 and the like.

JP-A-6-196349 JP 2003-293187 A JP 2004-68026 A

However, in recent years, the long-term reliability at a higher temperature has been demanded for the heat-resistant peelability, and even for a Cu-Zn-based alloy having a relatively good heat-resistant peelability in the past. Good heat-resistant peelability has come to be demanded.
An object of the present invention is to provide a Cu-Zn alloy tin plating strip having improved heat-resistant peelability of tin plating, and particularly improved heat-resistant peeling with respect to Cu undercoat or Cu / Ni double-layer undercoat It is providing the Cu-Zn type alloy tin plating strip which has the property.

As a result of earnestly researching measures for improving the heat release property of the tin-plated strip of the Cu—Zn alloy, the present inventor has greatly improved the heat release property when the C concentration at the interface between the plating layer and the base material is kept low. I found that it can be improved.
The present invention has been made based on this discovery and is as follows.
(1) Cu-Zn characterized in that a copper base alloy containing 15 to 40% by mass of Zn is used as a base material, and the C concentration at the interface between the plating layer and the base material is 0.10% by weight or less. Alloy tin-plated strip.
(2) A copper-based alloy containing 15 to 40% by mass of Zn is used as a base material. From the surface to the base material, a plating film is composed of each layer of Sn phase, Sn—Cu alloy phase, and Cu phase. The thickness is 0.1 to 1.5 μm, the thickness of the Sn—Cu alloy phase is 0.1 to 1.5 μm, the thickness of the Cu phase is 0 to 0.8 μm, and C at the interface between the plating layer and the base material A Cu—Zn alloy tin plating strip having a concentration of 0.10% by mass or less.
(3) A copper-based alloy containing 15 to 40% by mass of Zn is used as a base material, and a plating film is composed of each layer of Sn phase, Sn—Cu alloy phase, and Ni phase from the surface to the base material. The thickness is 0.1 to 1.5 μm, the thickness of the Sn—Cu alloy phase is 0.1 to 1.5 μm, the thickness of the Ni phase is 0.1 to 0.8 μm, and the boundary surface between the plating layer and the base material A Cu-Zn alloy tin-plated strip having a C concentration of 0.10% by mass or less.
(4) Cu-Zn alloy tin plating according to any one of (1) to (3), wherein the base material is a copper-based alloy containing 15 to 40% by mass of Zn and the balance being composed of Cu and inevitable impurities. Article.
(5) The base material further contains at least one selected from the group consisting of Sn, Ni, Fe, Mn, Co, Ti, Cr, Zr, Al and Ag in a range of 0.005 to 0.5 mass% in total. (4) Cu-Zn alloy tin-plated strip.
(6) The base material is a copper-based alloy containing 15 to 40% by mass of Zn, 8 to 20% by mass of Ni, and 0 to 0.5% by mass of Mn with the balance being Cu and inevitable impurities. (1)-(3) Cu-Zn type alloy tin-plating strip in any one of.
(7) The base material further contains at least one selected from the group consisting of Sn, Fe, Co, Ti, Cr, Zr, Al, and Ag in a range of 0.005 to 0.5 mass% in total (6) Cu-Zn alloy tin plating strip.
Note that tin plating of a Cu—Zn-based alloy may be performed before pressing a part (pre-plating) or after pressing (post-plating). In both cases, the effect of the present invention is obtained. It is done.

(1) Ingredients of base material The present invention is intended for copper alloys containing 15 to 40% by mass of Zn, and the effects of the invention do not appear for copper alloys whose Zn is out of this range. .
There is brass as a copper alloy containing 15 to 40% by mass of Zn. JIS-H3100 defines brass such as C2600, C2680, and C2720. An alloy that exhibits the effects of the present invention is brass.
There is a white as a copper alloy other than brass containing 15 to 40% by mass of Zn. Western white contains Ni in addition to Zn, and also contains a small amount of Mn. In JIS-H3110 and JIS-H3130, whites such as C7521, C7541 and C7701 are defined. Examples of alloys exhibiting the effects of the present invention include white.
Further, the copper alloy base material containing no Ni and Mn of the present invention is Sn, Ni, Fe, Mn, Co, Ti, Cr, for the purpose of improving the strength, heat resistance, stress relaxation resistance, etc. of the alloy. One or more of Zr, Al and Ag can be added in a total amount of 0.005 to 0.5 mass%. When the total amount is less than 0.005% by mass, the effect of improving the characteristics is not exhibited. On the other hand, when the total amount exceeds 0.5% by mass, problems such as a decrease in conductivity, a decrease in manufacturability, and an increase in raw material costs occur. Similarly, for the alloy of claim 6 containing Ni and Mn, 0.005 to 0.5 mass in total of at least one of Sn, Fe, Co, Ti, Cr, Zr, Al and Ag % Can be added.

(2) C concentration at the interface between the plating layer and the base material When the C concentration at the interface between the plating layer and the base material exceeds 0.10% by mass, the heat-resistant peelability decreases. Therefore, the C concentration is specified to be 0.10% by mass or less. Here, the C concentration at the boundary surface between the plating layer and the base material is, for example, a concentration profile in the depth direction of C of the sample after degreasing obtained by GDS (glow discharge emission spectroscopy analyzer). The C concentration at the peak apex that appears at the position corresponding to the boundary surface with the material.

Manufacturing condition factors affecting the C concentration at the interface between the plating layer and the base material include final cold rolling conditions and subsequent degreasing conditions. That is, since rolling oil is used in cold rolling, the rolling oil is interposed between the roll and the material to be rolled. When this rolling oil is sealed on the surface of the material to be rolled and remains without being removed by degreasing in the next step, a C segregation layer is formed at the plating / base material interface through a plating step (electrodeposition and reflow).
In the cold rolling process, the material is repeatedly passed through a rolling mill to finish the material to a predetermined thickness. FIG. 1 schematically shows a process in which rolling oil is sealed on the surface of a material to be rolled during rolling. (A) is a to-be-rolled material cross section before rolling. (B) is a cross-section of the material to be rolled after rolling using a roll having a large surface roughness that is usually used, where the surface of the material to be rolled is uneven, and rolling oil is accumulated in the recess. (C) is a cross section of the rolled material after rolling using a roll having a small surface roughness as the final pass after (b), and the rolling oil accumulated in the recesses in (b) is applied to the surface of the rolled material. It is enclosed.

FIG. 1 shows that it is important to use a roll having a low surface roughness in the pass before the final pass using a roll having a low surface roughness in order to suppress the inclusion of rolling oil. An important factor other than the surface roughness of the roll is the viscosity of the rolling oil. The rolling oil having a lower viscosity and better fluidity is less likely to be encapsulated on the surface of the material to be rolled.
As a method for reducing the surface roughness of the roll, there are a method of polishing the roll surface using a grindstone having a fine particle size, a method of plating the roll surface, etc., but these require considerable labor and cost. Moreover, if the surface roughness of the roll is made small, slips are likely to occur between the roll surface and the material to be rolled, and problems such as the inability to increase the rolling speed (decrease in efficiency) occur. For this reason, although rolls with a small surface roughness were used in the final pass to create the surface roughness of the product, those skilled in the art should avoid using rolls with a low surface roughness in passes other than the final pass. It was done. Also, the use of rolling oil having a low kinematic viscosity has been avoided for reasons such as increased wear on the surface of the rolling roll.
For the first time, it has been found that it is important to reduce the C concentration at the interface between the plating layer and the base material in order to improve the heat-resistant peelability of tin plating. For that purpose, it is effective to suppress the inclusion of the rolling oil by using a roll having a small surface roughness in the pass before the final pass and using a rolling oil having a low kinematic viscosity and good fluidity. It has been shown.

The maximum height roughness Rz of the roll having a small surface roughness used before the final pass is preferably 3.0 μm or less, more preferably 2.0 μm or less, and most preferably 1.0 μm or less. When Rz exceeds 3.0 μm, rolling oil is likely to be enclosed, and the C concentration at the boundary surface is unlikely to decrease. The kinematic viscosity (measured at 40 ° C.) of the rolling oil used is preferably 15 mm ² / s or less, more preferably 10 mm ² / s or less, and most preferably 5 mm ² / s or less. When the viscosity exceeds 15 mm ² / s, the rolling oil is easily enclosed, and the C concentration at the boundary surface is difficult to decrease.
Patent Document 3 also focuses on the C concentration. This C concentration is the average C concentration in the Sn plating layer, and the C concentration at the interface between the plating layer and the base material, which is a component of the present invention. Is different. The average C concentration in the Sn plating layer varies depending on the amount of brightener and additive in the plating solution and the plating current density. If it is less than 0.001% by mass, the Sn plating thickness is uneven, and 0.1% by mass. It is said that the contact resistance increases when the value exceeds. Therefore, it is clear that the technique of Patent Document 3 is different from the technique of the present invention.

(3) Thickness of plating (3-1) Cu base plating In the case of Cu base plating, a Cu plating layer and a Sn plating layer are sequentially formed on a Cu-Zn alloy base material by electroplating, and then a reflow process is performed. . By this reflow treatment, the Cu plating layer and the Sn plating layer react to form an Sn—Cu alloy phase, and the plating layer structure becomes an Sn phase, an Sn—Cu alloy phase, and a Cu phase from the surface side.
The thickness of each phase after reflow is
-Sn phase: 0.1-1.5 μm,
Sn-Cu alloy phase: 0.1 to 1.5 μm
Cu phase: 0 to 0.8 μm
Adjust to the range.
When the Sn phase is less than 0.1 μm, the solder wettability decreases, and when it exceeds 1.5 μm, the thermal stress generated inside the plating layer when heated is increased, and the plating peeling is promoted. A more preferable range is 0.2 to 1.0 μm.
Since the Sn—Cu alloy phase is hard, if it exists in a thickness of 0.1 μm or more, it contributes to a reduction in insertion force. On the other hand, when the thickness of the Sn—Cu alloy phase exceeds 1.5 μm, the thermal stress generated inside the plating layer when heated is increased, and the plating peeling is promoted. A more preferable thickness is 0.5 to 1.2 μm.

In the Cu—Zn alloy, solder wettability is improved by performing Cu base plating. Therefore, it is necessary to apply a Cu base plating of 0.1 μm or more during electrodeposition. This Cu base plating may be consumed and lost for Sn—Cu alloy phase formation during reflow. That is, the lower limit value of the Cu phase thickness after reflow is not regulated, and the thickness may be zero.
The upper limit value of the thickness of the Cu phase is 0.8 μm or less in the state after reflow. When the thickness exceeds 0.8 μm, the thermal stress generated inside the plating layer when heated is increased, and the plating peeling is promoted. A more preferable thickness of the Cu phase is 0.4 μm or less.
In order to obtain the above plating structure, the thickness of each plating at the time of electroplating is adjusted as appropriate within the range of 0.5 to 1.8 μm for Sn plating and 0.1 to 1.2 μm for Cu plating. The reflow treatment is performed under appropriate conditions in the range of ˜600 ° C. and 3 to 30 seconds.

(3-2) Cu / Ni foundation plating In the case of Cu / Ni foundation plating, a Ni plating layer, a Cu plating layer, and a Sn plating layer are sequentially formed on a Cu-Zn alloy base material by electroplating, and then reflow treatment is performed. I do. By this reflow treatment, the Cu plating reacts with Sn to become a Sn—Cu alloy phase, and the Cu phase disappears. On the other hand, the Ni layer remains almost in the state after electroplating. As a result, the structure of the plating layer becomes Sn phase, Sn—Cu alloy phase, and Ni phase from the surface side.
The thickness of each phase after reflow is
-Sn phase: 0.1-1.5 μm,
Sn-Cu alloy phase: 0.1 to 1.5 μm
・ Ni phase: 0.1-0.8μm
Adjust to the range.
When the Sn phase is less than 0.1 μm, the solder wettability decreases, and when it exceeds 1.5 μm, the thermal stress generated inside the plating layer when heated is increased, and the plating peeling is promoted. A more preferable range is 0.2 to 1.0 μm.
Since the Sn—Cu alloy phase is hard, if it exists in a thickness of 0.1 μm or more, it contributes to a reduction in insertion force. On the other hand, when the thickness of the Sn—Cu alloy phase exceeds 1.5 μm, the thermal stress generated inside the plating layer when heated is increased, and the plating peeling is promoted. A more preferable thickness is 0.5 to 1.2 μm.

The thickness of the Ni phase is 0.1 to 0.8 μm. If the thickness of Ni is less than 0.1 μm, the corrosion resistance and heat resistance of the plating deteriorate. When the thickness of Ni exceeds 0.8 μm, the thermal stress generated inside the plating layer when heated is increased, and the plating peeling is promoted. A more preferable thickness of the Ni phase is 0.1 to 0.3 μm.
In order to obtain the plating structure, the thickness of each plating during electroplating is in the range of 0.5 to 1.8 μm for Sn plating, 0.1 to 0.4 μm for Cu plating, and 0.1 to 0.4 μm for Ni plating. It adjusts suitably in the range of 0.8 micrometer, and performs a reflow process on suitable conditions in the range of 230-600 degreeC and 3 to 30 second.

The manufacturing, plating, and measuring methods employed in the examples of the present invention are shown below.
Using a high frequency induction furnace, 2 kg of electrolytic copper was dissolved in a graphite crucible having an inner diameter of 60 mm and a depth of 200 mm. After covering the surface of the molten metal with a piece of charcoal, a predetermined amount of Zn and other alloy elements were added.
Thereafter, the molten metal was cast into a mold to produce an ingot having a width of 60 mm and a thickness of 30 mm, and processed into a Cu underlayer reflow Sn plating material and a Cu / Ni underlayer reflow Sn plating material in the following steps. In order to obtain samples with different C concentrations at the plating / matrix interface, the conditions of step 9 were varied.

(Step 1) After heating at 900 ° C. for 3 hours, it was hot-rolled to a thickness of 8 mm.
(Step 2) The oxidized scale on the surface of the hot rolled plate was ground and removed with a grinder.
(Process 3) Cold rolled to a plate thickness of 1.5 mm.
(Step 4) Heating was performed at 400 ° C. for 30 minutes as recrystallization annealing.
(Step 5) Pickling with a 10 mass% sulfuric acid-1 mass% hydrogen peroxide solution and mechanical polishing with # 1200 emery paper were sequentially performed to remove the surface oxide film.
(Step 6) Cold rolling to a plate thickness of 0.5 mm.
(Step 7) Heating was performed at 400 ° C. for 30 minutes as recrystallization annealing.
(Step 8) Pickling with a 10% by mass sulfuric acid-1% by mass hydrogen peroxide solution was performed to remove the surface oxide film.

(Step 9) Cold rolling to a plate thickness of 0.3 mm. The number of passes was two, and the first pass was processed to 0.38 mm, and the second pass was processed to 0.3 mm. In the second pass, a roll whose surface Rz (maximum height roughness) was adjusted to 1.0 μm was used. In the first pass, Rz on the roll surface was changed at four levels of 1, 2, 3, and 4 μm. The kinematic viscosity of the rolling oil (common to the first pass and the second pass) was changed at three levels of 5, 10 and 15 mm ² / s.
(Step 10) Electrolytic degreasing was performed under the following conditions in a alkaline aqueous solution using the sample as a cathode.
Current density: 3 A / dm ² . Degreasing agent: Trademark “Pakuna P105” manufactured by Yuken Industry Co., Ltd. Degreasing agent concentration: 40 g / L. Temperature: 50 ° C. Time 30 seconds. Current density: 3 A / dm ² .
(Step 11) Pickling was performed using a 10% by mass sulfuric acid aqueous solution.

(Step 12) Ni base plating was performed under the following conditions (only in the case of Cu / Ni base).
-Plating bath composition: nickel sulfate 250 g / L, nickel chloride 45 g / L, boric acid 30 g / L.
-Plating bath temperature: 50 ° C.
Current density: 5A / dm ^2.
・ Ni plating thickness is adjusted by electrodeposition time.
(Step 13) Cu base plating was performed under the following conditions.
-Plating bath composition: copper sulfate 200 g / L, sulfuric acid 60 g / L.
-Plating bath temperature: 25 ° C.
Current density: 5A / dm ^2.
・ Cu plating thickness is adjusted by electrodeposition time.
(Step 14) Sn plating was performed under the following conditions.
Plating bath composition: stannous oxide 41 g / L, phenol sulfonic acid 268 g / L, surfactant 5 g / L.
-Plating bath temperature: 50 ° C.
Current density: 9A / dm ^2.
・ Sn plating thickness is adjusted by electrodeposition time.
(Step 15) As a reflow treatment, the sample was inserted into a heating furnace adjusted to 400 ° C. and the atmosphere gas to nitrogen (oxygen 1 vol% or less) for 10 seconds and cooled with water.

The following evaluation was performed about the sample produced in this way.
(A) Component analysis of base material After the plating layer was completely removed by mechanical polishing and chemical etching, the concentrations of Zn and other alloy elements were measured by ICP-emission spectroscopy.
(B) Plating thickness measurement by electrolytic membrane pressure gauge The thickness of the Sn phase and the Sn—Cu alloy phase was measured for the sample after reflow. Note that the thickness of the Cu phase and Ni phase cannot be measured by this method.

(C) Surface analysis by GDS After the reflowed sample was ultrasonically degreased in acetone, the concentration profiles of Sn, Cu, Ni, and C in the depth direction were determined by GDS (glow discharge emission spectroscopic analyzer). The measurement conditions are as follows.
Apparatus: JY5000RF-PSS type manufactured by JOBIN YBON.
-Current Method Program: CNBintel-12aa-0.
Mode: Constant EleCtriC Power = 40W.
Ar-Presser: 775 Pa.
-Current Value: 40 mA (700 V).
-Flush Time: 20 sec.
Preburn Time: 2 sec.
Determination Time: Analysis Time = 30 sec, Sampling Time = 0.020 sec / point.

From the C concentration profile data obtained by GDS, the C concentration at the plating / base metal interface was determined. As a typical concentration profile of C, FIG. 2 shows data of Invention Example 2 (Table 1, Cu base plating) described later. A peak of C is observed at a depth of 1.6 μm (a boundary surface between the plating layer and the base material). The peak height was read and used as the C concentration at the plating / base metal interface.
Further, from the Cu concentration profile, the thickness of the Cu base plating (Cu phase) remaining after the reflow was obtained. FIG. 3 shows data of Invention Example 24 (Table 2, Cu base plating) described later. A layer having a Cu concentration higher than that of the base material is observed at a depth of 1.7 μm. This layer is the Cu base plating remaining after the reflow, and the thickness of the portion where the Cu concentration is higher than that of the base material is read as the thickness of the Cu phase. In addition, when the layer whose Cu is higher than a base material was not recognized, it was considered that Cu undercoat disappeared (the thickness of Cu phase was zero). Similarly, the thickness of the Ni base plating (Ni phase) was determined from the Ni concentration profile data.

(D) Heat-resistant peelability A strip test piece having a width of 10 mm was collected and heated at a temperature of 160 ° C. for up to 3000 hours in the atmosphere. In the meantime, the sample was taken out from the heating furnace every 100 hours, and 90 ° bending and bending back with a bending radius of 0.5 mm were performed (90 ° bending was reciprocated once). Next, an adhesive tape (# 851 manufactured by 3M) was applied to the surface of the inner periphery of the bend and peeled off. Thereafter, the surface of the inner periphery of the sample was observed with an optical microscope (magnification 50 times), and the presence or absence of plating peeling was examined.

Relationship between C concentration of plating layer / base material interface and heat-resistant peelability (Invention Examples 1 to 21 and Comparative Examples 1 to 9)
Table 1 shows an example in which the influence of the C concentration at the plating layer / base metal interface on the heat-resistant peelability was investigated. The C concentration at the plating layer / base material interface is changed by adjusting Rz and rolling oil kinematic viscosity on the roll surface to 1 to 4 μm and 5 to 15 mm ² / s, respectively.
For the Cu base plating material, electroplating was performed with a Cu thickness of 0.3 μm and a Sn thickness of 1.0 μm, and after reflowing at 400 ° C. for 10 seconds, all the inventive examples and comparative examples were Sn phase. The thickness was about 0.6 μm, the thickness of the Cu—Sn alloy phase was about 1 μm, and the Cu phase disappeared.
For the Cu / Ni base plating material, electroplating was performed with a Ni thickness of 0.2 μm, a Cu thickness of 0.3 μm, and a Sn thickness of 0.8 μm, and reflowed at 400 ° C. for 10 seconds. In both examples and comparative examples, the thickness of the Sn phase is about 0.4 μm, the thickness of the Cu—Sn alloy phase is about 1 μm, the Cu phase disappears, and the Ni phase remains at the thickness during electrodeposition (0.2 μm). It remained.
In Invention Examples 1 to 21, which are the alloys of the present invention, the C concentration at the plating layer / base metal interface is 0.10% by mass or less, and plating peeling does not occur even when heated at 160 ° C. for 3000 hours. On the other hand, in Comparative Examples 1-9, C density | concentration exceeds 0.10 mass% and peeling time is less than 3000 hours. It can also be seen that the C concentration at the plating layer / base metal interface can be lowered by reducing the surface roughness of the rolling roll and lowering the viscosity of the rolling oil.

表中の「−」は無添加を表す。

"-" In the table represents no addition.

Relationship between plating thickness and heat-resistant peelability (Invention Examples 22 to 36 and Comparative Examples 10 to 15)
Tables 2 and 3 show examples in which the influence of the plating thickness on the heat-resistant peelability was investigated. The base material composition was Cu-30.5 mass% Zn. In Step 9, a rolling roll having an Rz of 2 μm in the first pass was used, and a rolling oil having a kinematic viscosity of 10 mm ² / s was used in the first pass and the second pass. As a result, the C concentration at the plating layer / base material interface in each sample was within the range of 0.07 to 0.09 mass%.
Table 2 (Invention Examples 22 to 29 and Comparative Examples 10 to 12) shows data for Cu base plating. With respect to Invention Examples 22 to 29 which are the alloys of the present invention, plating peeling does not occur even when heated at 160 ° C. for 3000 hours.
In Invention Examples 22 to 25 and Comparative Example 12, the Sn electrodeposition thickness is 0.9 μm and the thickness of the Cu base is changed. In Comparative Example 12 in which the Cu underlayer thickness after reflow exceeds 0.8 μm, the peeling time is less than 3000 hours.
In Invention Examples 24, 26 to 29 and Comparative Examples 10 to 11, the electrodeposition thickness of the Cu base was 0.8 μm, and the Sn thickness was changed. In Comparative Example 10 in which the Sn electrodeposition thickness was 2.0 μm and reflow was performed under the same conditions as the others, the thickness of the Sn phase after reflow exceeded 1.5 μm. In Comparative Example 11 in which the Sn electrodeposition thickness was 2.0 μm and the reflow time was extended, the Sn—Cu alloy phase thickness after reflow exceeded 1.5 μm. In these alloys in which the thickness of the Sn phase or the Sn—Cu alloy phase exceeds the specified range, the peeling time is less than 3000 hours.

Table 3 (Invention Examples 30 to 36 and Comparative Examples 13 to 15) shows data in the Cu / Ni base plating. With respect to Invention Examples 30 to 36, which are the alloys of the present invention, plating peeling does not occur even when heated for 3000 hours.
In Invention Examples 30 to 32 and Comparative Example 15, the electrodeposition thickness of Sn is 0.9 μm, the electrodeposition thickness of Cu is 0.2 μm, and the thickness of the Ni base is changed. In Comparative Example 15 in which the thickness of the Ni phase after reflow exceeded 0.8 μm, the peeling time was less than 3000 hours.
In Invention Examples 33 to 36 and Comparative Example 13, the electrodeposition thickness of the Cu base was 0.15 μm, the electrodeposition thickness of the Ni base was 0.2 μm, and the Sn thickness was changed. In Comparative Example 13 in which the thickness of the Sn phase after reflow exceeded 1.5 μm, the peeling time was less than 3000 hours.
In Comparative Example 14 in which the Sn electrodeposition thickness was 2.0 μm, the Cu electrodeposition thickness was 0.6 μm, and the reflow time was extended from the other examples, the Sn—Cu alloy phase thickness exceeded 1.5 μm, and peeling The time is less than 3000 hours.

It is a schematic diagram which shows the process in which rolling oil is enclosed by the to-be-rolled material surface during cold rolling. It is the profile of the depth direction of C density | concentration of the sample of invention example 2 (Table 1, Cu base plating). It is the profile of the depth direction of Cu and Sn density | concentration of the sample of invention example 24 (Table 2, Cu base plating).

Claims (4)

A copper-based alloy containing 15 to 40% by mass of Zn and the balance being composed of Cu and inevitable impurities is used as a base material, and plating is performed on the Sn phase, Sn—Cu alloy phase, and Ni phase from the surface to the base material. A coating is formed, the thickness of the Sn phase is 0.1 to 1.5 μm, the thickness of the Sn—Cu alloy phase is 0.1 to 1.5 μm, the thickness of the Ni phase is 0.1 to 0.8 μm, A Cu—Zn-based alloy tin-plated strip having a C concentration of 0.10% by mass or less at the interface between the layer and the base material. The base material further contains at least one selected from the group consisting of Sn, Ni, Fe, Mn, Co, Ti, Cr, Zr, Al, and Ag in a range of 0.005 to 0.5 mass% in total. 1. A Cu—Zn alloy tin plating strip according to 1. 15 to 40 wt% of Zn, 8 to 20 wt% of Ni, claim 1 of from composed of copper based alloy 0-0.5 wt% of content and balance Cu and unavoidable impurities of Mn to the base material The Cu-Zn alloy tin plating strip described. The Cu according to claim 3 , wherein the base material further contains at least one selected from the group consisting of Sn, Fe, Co, Ti, Cr, Zr, Al and Ag in a range of 0.005 to 0.5 mass% in total. -Zn-based alloy tin plating strip.

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