JP2007291459A - TINNED STRIP OF Cu-Sn-P-BASED ALLOY - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tinned strip of Cu-Sn-P-based alloy, in which the thermal peeling resistance of a tin plating is improved. <P>SOLUTION: In the tinned strip of Cu-Sn-P-based alloy comprising, as a base material, a Cu-based alloy containing Sn in an amount of 1-12 mass% and P in an amount of 0.01-0.35 mass%, the C-concentration in the boundary face between a plated layer and the base material is adjusted to be ≤0.10 mass%. The base material may further contain 0.005-3.0 mass% in total of at least one kind selected from the group comprising Zn, Fe, Ni, Si, Mn, Co, Ti, Cr, Zr, Al and Ag. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a Cu—Sn—P 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—Sn—P-based alloys are widely used as electrical contact materials for connectors, terminals, relays, switches, etc. due to their excellent spring properties. A typical Cu-Sn-P alloy is phosphor bronze, and alloys such as C5111, C5102, C5191, C5121, and C5210 are defined in JIS H3110 and H3130. When using a Cu—Sn—P alloy as an electrical contact material, Sn plating is often applied in order to stably obtain a low contact resistance. The Sn plating strip of Cu-Sn-P 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, and consumer connectors. It is used in large quantities for electrical and electronic parts such as contacts.

For Sn plating strips of Cu-Sn-P alloys, after degreasing and pickling, if necessary, a base plating layer is formed by electroplating, then an Sn plating layer is formed by electroplating, and finally reflow is performed. Manufactured in a step of applying a treatment to melt the Sn plating layer.
Although the Cu base plating is often applied to the Sn plating strip of the copper-plated product, in the Cu base Sn plating of the Cu—Sn—P based alloy, the plating layer is more than the base material when kept at a high temperature for a long time. There is a problem that a phenomenon of peeling (hereinafter referred to as thermal peeling) is likely to occur. Therefore, in Sn plating of a Cu—Sn—P based alloy, it is often the case that base plating is not performed or Ni base plating is relatively difficult to cause thermal peeling. In particular, for applications requiring heat resistance, a Cu base plating may be further applied on the Ni base plating (hereinafter referred to as a Cu / Ni two-layer base). When Sn plating is performed on the Cu / Ni two-layer base plating and reflow treatment is performed, the structure of the plated film layer after reflow becomes Sn phase, Cu-Sn phase, Ni phase, and base material from the surface. 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, long-term reliability at higher temperatures has been demanded for heat-resistant peelability, and there is no undercoating or Cu / Ni two-layer undercoating Cu having relatively good heat-resistant peelability. Even better resistance to heat peeling has been demanded for Sn-P alloy Sn plating strips.
An object of the present invention is to provide a Cu-Sn-P alloy tin plating strip with improved heat-resistant peelability of tin plating, and particularly improved heat resistance with no base plating or Cu / Ni two-layer base plating It is to provide a Cu—Sn—P alloy tin plating strip having peelability.

  The present inventor has intensively studied measures for improving the heat-resistant peelability of the tin-plated strip of the Cu—Sn—P alloy. As a result, it has been found that when the C concentration at the interface between the plating layer and the base material is kept low, the heat-resistant peelability can be greatly improved.

The present invention has been made based on this discovery and is as follows.
(1) A copper-based alloy containing 1 to 12% by mass of Sn and 0.01 to 0.35% by mass of P is used as a base material, and the C concentration at the interface between the plating layer and the base material is 0.10%. % Cu-Sn-P alloy tin-plated strip.
(2) A copper-based alloy containing 1 to 12% by mass of Sn and 0.01 to 0.35% by mass of P is used as a base material, and from the surface to the base material, each layer of Sn phase and Sn—Cu alloy phase A plating film is formed, the Sn phase thickness is 0.1 to 1.5 μm, the Sn—Cu alloy phase thickness is 0.1 to 1.5 μm, and the C concentration at the interface between the plating layer and the base material is A Cu—Sn—P alloy tin plating strip characterized by being 0.10% by mass or less.
(3) A copper base alloy containing 1 to 12% by mass of Sn and 0.01 to 0.35% by mass of P is used as a base material, and from the surface to the base material, Sn phase, Sn-Cu alloy phase, Ni phase A plating film is composed of each layer of Sn, the thickness of Sn phase is 0.1 to 1.5 μm, the thickness of Sn—Cu alloy phase is 0.1 to 1.5 μm, and the thickness of Ni phase is 0.1 to 0.8 μm. A Cu—Sn—P alloy tin-plated strip, wherein the C concentration at the interface between the plating layer and the base material is 0.10% by mass or less.
(4) The base material is at least one selected from the group consisting of Zn, Fe, Ni, Si, Mn, Co, Ti, Cr, Zr, Al, and Ag in a range of 0.005 to 1.0 mass% in total. The Cu-Sn-P alloy tin plating strip according to any one of (1) to (3).
(5) It is characterized by adjusting the C concentration at the boundary surface between the plating layer and the base material after reflowing to 0.10% by mass or less by suppressing the inclusion of rolling oil on the base material surface in the final rolling. The manufacturing method of the Cu-Sn-P system alloy tin plating strip in any one of (1)-(4).
Note that tin plating of a Cu—Sn—P alloy may be performed before pressing the part (pre-plating) or after pressing (post-plating). In both cases, the effect of the present invention is achieved. Is obtained.

(1) Base Material Components The present invention is directed to a copper alloy containing 1 to 12% by mass of Sn and 0.01 to 0.35% by mass of P. When the Sn content is less than 1% by mass, the strength is insufficient, and when the Sn content exceeds 12% by mass, the decrease in the conductivity becomes significant. Sn is preferably 3 to 11% by mass. When P is less than 0.01% by mass, manufacturability (particularly melt castability) is lowered, and when it exceeds 0.35% by mass, the conductivity is remarkably lowered. P is preferably 0.03 to 0.20% by mass.
The copper alloy base material of the present invention is made of Zn, Fe, Ni, Si, Mn, Co, Ti, Cr, Zr, Al and Ag for the purpose of improving the strength, heat resistance, stress relaxation resistance, etc. of the alloy. At least one selected from the group can be added in a total amount of 0.005 to 1.0 mass%, preferably 0.05 to 0.5 mass%. When the total amount of these elements 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 1.0% by mass, problems such as a decrease in conductivity, a decrease in manufacturability, and an increase in raw material costs occur.

(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. That is, it is not preferable to use a roll having a large surface roughness even once in all passes before the final pass because it causes unevenness on the surface of the material to be rolled. An important factor other than the roll roughness is the viscosity of the rolling oil. The rolling oil having a lower viscosity and better fluidity is less likely to be sealed 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 thermal peelability of tin plating according to the present invention. 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. In Patent Document 3, the average C concentration in the Sn plating layer varies depending on the amount of brightener, additive, and plating current density in the plating solution. If the amount is less than 0.001% by mass, unevenness of the Sn plating thickness occurs. If it exceeds 0.1% by mass, the contact resistance is supposed to increase. 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) No base plating In the case of no base plating, an Sn plating layer is formed directly on the Cu—Sn—P alloy base material by electroplating, and then a reflow treatment is performed. By this reflow process, Cu in the alloy base material reacts with the Sn plating layer to form an Sn—Cu alloy phase, and the plating layer structure becomes an Sn phase and an Sn—Cu alloy 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
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 order to obtain the above-mentioned plating structure, the thickness of Sn plating at the time of electroplating is appropriately adjusted in the range of 0.5 to 1.8 μm, and under appropriate conditions in the range of 230 to 600 ° C. and 3 to 30 seconds. Perform reflow processing.

(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-Sn-P alloy base material by electroplating, and thereafter Perform reflow processing. 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 molten metal surface with charcoal pieces, a predetermined amount of Sn, P 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 baseless reflow Sn plating material and a Cu / Ni base 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 12 were varied.

(Step 1) Heating was performed at 700 ° C. for 3 hours as homogenization annealing.
(Step 2) The oxidized scale on the surface was ground and removed with a grinder.
(Process 3) Cold rolled to a plate thickness of 10 mm.
(Step 4) Heating was performed at 500 ° C. for 3 hours as homogenization annealing.
(Step 5) The oxidized scale on the surface was ground and removed with a grinder.
(Step 6) Cold rolling to a plate thickness of 1.5 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 and mechanical polishing with # 1200 emery paper were sequentially performed to remove the surface oxide film.
(Step 9) Cold rolling to a plate thickness of 0.5 mm.
(Step 10) Heating was performed at 400 ° C. for 30 minutes as recrystallization annealing.
(Step 11) Pickling with a 10% by mass sulfuric acid-1% by mass hydrogen peroxide solution was performed to remove the surface oxide film.

(Step 12) 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. Further, 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 13) Electrolytic degreasing was performed under the following conditions in an 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 14) Pickling was performed using a 10% by mass sulfuric acid aqueous solution.

(Step 15) 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 16) Cu base plating was performed under the following conditions (only in the case of Cu / Ni base).
-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 17) 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 18) 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 Sn, P and other alloy elements were measured by ICP-emission spectroscopy.
(B) Plating thickness measurement by electrolytic film thickness meter The thickness of the Sn phase and the Sn—Cu alloy phase was measured on the sample after reflow. In this method, the thickness of the Ni phase cannot be measured.

(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.
・ Equipment: JY5000RF-PSS type manufactured by JOBIN YBON ・ Current Method Program: CNBinteel-12aa-0.
・ Mode: Constant Electric Power = 40W.
・ Ar-Presser: 775Pa.
・ Current Value: 40mA (700V).
・ Flush Time: 20sec.
・ Preburn Time: 2sec.
-Determination Time: Analysis Time = 30sec, Sampling Time = 0.020sec / 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, no 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, the thickness of the Ni base plating (Ni phase) was obtained from the Ni concentration profile data obtained by GDS.

(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 attached 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. And the heating time until plating peeling generate | occur | produced was calculated | required.

Relationship between C concentration of plating layer / base material interface and heat-resistant peelability (Invention Examples 1 to 24 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. In step 12, the roll surface roughness Rz and the rolling oil kinematic viscosity are adjusted to ¹ to 4 μm and 5 to 15 mm ² / s, respectively, thereby changing the C concentration at the plating layer / base material interface.
For the material without base plating, electroplating was performed with a Sn thickness of 1.2 μm and reflowed at 400 ° C. for 10 seconds. In all the inventive examples and comparative examples, the Sn phase thickness was about 0.8 μm, Cu The thickness of the —Sn alloy phase was about 0.8 μm.
For the Cu / Ni base plating material, electroplating was performed with a Ni thickness of 0.3 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 (0.3 μm). It remained.
In Invention Examples 1 to 24, 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.

Relationship between plating thickness and heat-resistant peelability (Invention Examples 25 to 36 and Comparative Examples 10 to 14)
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-6.0 mass% -0.12 mass% P. In step 12, 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 25 to 29 and Comparative Examples 10 and 11) changes the thickness of Sn in the case of no base plating. In Invention Examples 25 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 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 temperature was high, 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 12 to 14) 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 14, 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 14 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 12, 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 12 in which the thickness of the Sn phase after reflow exceeds 1.5 μm, the peeling time is less than 3000 hours.
In Comparative Example 13 in which the Sn electrodeposition thickness was 2.0 μm, the Cu electrodeposition thickness was 0.6 μm, and the reflow temperature was higher than that of 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 in invention example 2 (Table 1, no base plating).

Claims (5)

  A copper base alloy containing 1 to 12% by mass of Sn and 0.01 to 0.35% by mass of P is used as a base material, and the C concentration at the boundary surface between the plating layer and the base material is 0.10% by weight or less. A Cu—Sn—P alloy tin-plated strip characterized by being.   A copper-based alloy containing 1 to 12% by mass of Sn and 0.01 to 0.35% by mass of P is used as a base material, and a plating film is formed on each layer of the Sn phase and the Sn—Cu alloy phase from the surface to the base material. The Sn phase has a thickness of 0.1 to 1.5 μm, the Sn—Cu alloy phase has a thickness of 0.1 to 1.5 μm, and the C concentration at the interface between the plating layer and the base material is 0.10. A Cu—Sn—P alloy tin-plated strip characterized by being less than or equal to mass%.   A copper-based alloy containing 1 to 12% by mass of Sn and 0.01 to 0.35% by mass of P is used as a base material. From the surface to the base material, each layer of Sn phase, Sn—Cu alloy phase and Ni phase A plating film 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-Sn-P alloy tin-plated strip, wherein the C concentration at the interface between the plating layer and the base material is 0.10 mass% or less.   Claim that the base material contains at least one selected from the group of Zn, Fe, Ni, Si, Mn, Co, Ti, Cr, Zr, Al, and Ag in a range of 0.005 to 1.0 mass% in total. Item 4. A Cu—Sn—P alloy tin-plated strip according to any one of Items 1 to 3.   The C concentration at the boundary surface between the reflowed plating layer and the base material is adjusted to 0.10% by mass or less by suppressing the sealing of rolling oil on the base material surface in the final rolling. Item 5. A method for producing a Cu-Sn-P alloy tin-plated strip according to any one of Items 1 to 4.