JPH02173233A - Coppery material excellent in thermal conductivity and corrosion resistance, heat-exchanger fin material, and their production - Google Patents

Abstract

PURPOSE:To manufacture a coppery material excellent in thermal conductivity and corrosion resistance by coating the surface of Cu or Cu alloy with an alloy consisting of an element having a diffusion coefficient into Cu lower than that of Zn and Zn and then applying homogenizing treatment to the above. CONSTITUTION:A film of an alloy consisting of an element having a diffusion coefficient into Cu lower than that of Zn and Zn is formed on the surface of Cu or Cu alloy. As the above Cu alloy, the one consisting of 0.01-0.13wt.% of one or more elements among Mg, Zn, Sn, Cd, Ag, Ni, P, Zr, Cr, Pb, and Al and the balance Cu and having >=90% IACS electric conductivity is used. Further, as the element having a diffusion coefficient into Cu lower than that of Zn, one or more elements among Ni, Co, Sn, and Al are suitably used. After the formation of the above alloy film, homogenizing treatment is carried out, by which an inner diffusion layer consisting of Cu and Zn is formed on the surface layer of the above Cu or Cu alloy and also a surface-side diffusion layer consisting of Cu, Zn, and the element having a diffusion coefficient into Cu lower than that of Zn is formed on the surface side. By this method, the corrosion resistance of the coppery material can be improved and deterioration in thermal conductivity can be prevented.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a copper-based material for use in heat exchangers, which has excellent corrosion resistance such as stress corrosion cracking resistance and dezincification corrosion resistance t'1, and has good thermal conductivity. This invention relates to fin materials and their manufacturing method.

[Prior art and problems to be solved by the invention] In general, copper-based materials such as pure copper, tough pitch copper, phosphorous-deoxidized copper, and brass are widely used in various fields such as electrical appliances, 711 slave devices, and heat exchangers. However, it is easily susceptible to surface corrosion such as oxidation and sulfidation, which impairs the appearance and has the disadvantage that it tends to have a serious effect on practical properties such as electrical connectivity and opening properties. It has the following. In addition, when used in automobile heat exchangers, salt corrosion caused by snow melting agents, etc. has become a problem in recent years, and this salt corrosion reduces the heat dissipation characteristics of the heat exchanger and further deteriorates its strength. It is having a significant impact.

Copper-based materials also have the disadvantage of causing stress corrosion cracking when placed in certain environments under tensile stress. This stress corrosion cracking is a form of corrosion, and among copper-based materials, purchased copper and phosphorus-deoxidized copper are susceptible to stress corrosion cracking, especially in an ammonia environment. Note that even pure copper often experiences stress corrosion cracking.

Therefore, copper-based materials with excellent corrosion resistance including stress corrosion cracking resistance are desired.
Second, like the u-Ni corrosion-resistant alloy. Although it is possible to alloy the material itself by adding a third element, this increases cost and is economically disadvantageous.

In addition, in the semiconductor field, the thermal conductivity of materials is one of the important characteristics due to the increase in heat generation due to high-density packaging, and high heat conductive materials are required. The same applies to the heat exchanger fin material. Copper has the excellent property of high electrical conductivity that satisfies this requirement, but if the material itself is alloyed to improve its corrosion resistance, the thermal conductivity will be drastically reduced, and although it is excellent in terms of corrosion resistance, This makes it unsuitable as a material that requires high conductivity.

On the other hand, since corrosion is originally a phenomenon on the surface, by modifying only the surface of the material, it is possible to suppress the decrease in thermal conductivity and improve corrosion resistance.

Based on this idea, for example, as a fin material for an automobile radiator, a Zn diffusion layer is formed on the surface of a Cu-based material to protect the internal core material as a sacrificial anode, and the thermal conductivity is determined by the heat imparted to the core material. Fin materials for exchangers have been proposed. However, in this case, the surface becomes a Cu-Zn alloy, so-called brass, which causes stress corrosion cracking and the desorption characteristic of brass (Zn disappears due to lead corrosion, making it difficult to maintain the sacrificial anode effect of Zn over a long period of time). There is a problem that cannot be done. In addition, the Zn diffusion layer formed on the surface layer has thermal conductivity.
Since the thickness is limited to about several micrometers on one side, if the dezincification corrosion of the Zn diffusion layer can be effectively suppressed and prevented, a fin material for heat exchangers with even better corrosion resistance can be expected, and it will also be possible to make the thickness thinner.

At present, in order to suppress such stress corrosion cracking and dezincification corrosion peculiar to brass, it is necessary to add a third element that is effective in improving corrosion resistance to the Cu-Zn diffusion layer and increase the Zn diffusion layer itself. Methods are being taken to improve corrosion resistance.

However, various elements can be considered to suppress dezincification corrosion, but
Generally, when these elements are added to copper, the decrease in thermal conductivity is significantly greater than when the same amount of Zn is added. Therefore, if sufficient amounts of these elements are added to the entire diffusion layer to effectively suppress and prevent dezincification corrosion, Zn
Dezincification corrosion is suppressed and corrosion resistance is improved compared to the case where the dezincification process is only carried out, but the thermal conductivity is greatly reduced.

[Means to solve the problem]

In view of this, as a result of various studies, the present invention reduces dezincification corrosion of the Zn diffusion layer formed on the surface of copper-based materials, and
We have developed a copper-based material with excellent thermal conductivity and corrosion resistance that reduces the decrease in thermal conductivity due to the addition of a third element into the diffusion layer, a fin material for heat exchangers, and a method for manufacturing them.

That is, the copper-based material and heat exchanger fin material of the present invention are Cu or C.
It is characterized by forming an inner diffusion layer made of Cu and Zn on the surface layer of the u alloy, and a surface side diffusion layer made of Cu, Zn, and an element whose diffusion coefficient into Cu is smaller than that of Zn on the surface side. It is something to do.

In addition, other copper-based materials and heat exchanger fin materials of the present invention include Mg
, Zn, Sn, Cd, Ag, Ni.

The surface of the heat-resistant copper strip with an electrical conductivity of 90% IACS or higher is made of Cu, containing one or more of P, Zr, Cr, Pb, and Al in a total of 0.01 to 0.13 w1%, and the balance being Cu. It is characterized in that an inner diffusion layer made of Zn and a surface side diffusion layer made of Cu, Zn, and an element whose diffusion coefficient into Cu is smaller than that of Zn are formed on the surface side thereof.

In addition, the present invention's manufacturing method for these copper-based materials and heat exchanger fin materials involves forming an alloy film on the surface of Cu or a Cu alloy consisting of Zn and an element whose diffusion coefficient into Cu is smaller than that of Zn, and then heating and diffusing the film. After processing, an inner diffusion layer consisting of Cu and Zn is formed on the surface layer of Cu or Cu alloy, and a Cu layer is formed on the surface side of the inner diffusion layer.
The method is characterized in that a surface-side diffusion layer is formed of an element having a smaller diffusion coefficient into Zn and Cu than Zn.

Still another manufacturing method of the present invention is to form an alloy film made of Zn and an element whose diffusion coefficient into Cu is smaller than that of Zn on the surface of Cu or a Cu alloy, and then perform a heating diffusion treatment to
There is an inner diffusion layer consisting of Cu and Zn on the surface layer of u or Cu alloy, and the diffusion coefficient of Cu and Zn into Cu is on the surface side.
The method is characterized in that a surface-side diffusion layer made of an element smaller than n is formed, and then rolling or wire drawing is performed.

In addition, other manufacturing methods of the present invention include Mg, Zn, and Sn.

Cd, Ag, Ni, P, Zr, Cr, Pb.

One or more types of Al in total from 0.01 to G, 1
After forming an alloy film consisting of an element whose diffusion coefficient into Cu is smaller than that of Zn and Zn on the surface of a heat-resistant copper strip with a conductivity of 90% or more and consisting of 3wt% and the balance Cu, heat diffusion treatment is performed. to add Cu and Z to the surface layer of Cu or Cu alloy.
The present invention is characterized in that an inner diffusion layer made of Zn and a surface side diffusion layer made of Cu, Zn, and an element whose diffusion coefficient into Cu is smaller than Zn are formed on the surface side thereof.

Furthermore, another manufacturing method of the present invention is Mg.

Zn, Sn, Cd, Ag, Ni, P, Zr.

Contains a total of 0.01 to 0.13 wt% of 77)l pJj or 2N or more in Cr, Pb, Al (1), and the remainder CI
After forming an alloy film consisting of Zn and an element whose diffusion coefficient into Cu is smaller than that of Zn on the surface of a heat-resistant copper strip with an electrical conductivity of 90% IACS or higher, a thermal diffusion treatment is performed to remove Cu.
Or an inner diffusion layer consisting of Cu and Zn on the surface layer of a Cu alloy, and a diffusion coefficient of Cu and Zn into Cu on the surface side -h
<Z A surface-side diffusion layer made of an element smaller than n is formed, and then rolling or wire drawing is performed.

In any of the above cases, the diffusion coefficient into Cu is Z n
Ni and Co are smaller elements.

It is effective to use one or more of Sn and Al.

[For production]

In the present invention, after forming a highly corrosion-resistant alloy film of Zn and an element (X) whose diffusion coefficient into Cu is smaller than that of Zn on the surface of Cu or a Cu alloy, Cu Utilizing the difference in the diffusion rate inside, Cu is added to the surface side.
C containing element X whose diffusion rate into the interior is lower than that of Zn
A surface side diffusion layer made of a u-Zn-X alloy is formed, and an inner diffusion layer made of a Cu-Zn alloy is formed on the F layer, which reduces surface dezincification corrosion and improves dezincification corrosion. The reduction in conductivity caused by adding a sufficient amount of the X element to suppress and prevent the diffusion layer is suppressed by keeping the X element on the surface side without distributing it throughout the diffusion layer.

However, the use of one or more of Ni, Co, Sn, and Al as the X element whose diffusion rate into Cu is slower than that of Zn is because it contains about 10 wt% or more of the iron group of Ni and Co. When forming a Zn alloy film using the hot dip method, it requires a high temperature of approximately 800°C or higher, which is extremely difficult and impractical from an industrial perspective. This is because an alloy plating film of iron group and Zn can be formed relatively easily by electroplating as an anomalous eutectoid alloy plating in which Zn, which is relatively base, precipitates preferentially.

In addition, regarding Sn and Al, it is possible to form a Zn-Sn alloy film industrially by electroplating method or hot dip method in the case of Sn.
! In this case, it is difficult to form a Zn-A1 alloy plating film by electroplating, but it is relatively easy to form a Zn-A1 alloy film by hot dipping or the like.

Further, when forming any alloy film, thermal spraying or PVD can be used in addition to the above-mentioned method.

〔Example〕

Example (1) Using a high-frequency melting furnace, electrolytic copper is melted while covering the area with charcoal, and predetermined additive elements are added to the melt to produce a uniform molten alloy, which has the composition shown in Table 1. The ingot was cast. After removing this ingot surface by 25-face front, 85Q'C
It was heated for X1 hours and rolled to a thickness of 10 mm by hot rolling. These were further subjected to repeated cold rolling and annealing to obtain a strip having a thickness of 0.035 mm.

Next, using plating baths (1) and (2) under the conditions shown in Table 2, these strips were combined with one of the plating baths as shown in Table 1, and a plating bath was prepared with a thickness of 1.2 μm. The heat-resistant hardness and electrical conductivity of the strips (S1 1 to 10) were plated with Zn-Ni or Zn-Sn alloy with the composition shown in Table 1 and then subjected to heat diffusion treatment at 350°C for 5 minutes. In addition, corrosion tests were conducted to measure the rate of deterioration of tensile strength, and the degree of dezincing was evaluated by observing the appearance.

Then, apply these results to the substrate in a plating bath (3).
Pure Zn plating with a thickness of 1.2 μm was performed using
Strip material subjected to heat diffusion treatment for 5 minutes (Nα11 to k13)
The results are shown in Table 1 along with the results of the above measurements.

Furthermore, Zn-Ni alloy plating was eliminated, and the
FIG. 1 shows an example of the results of line analysis using EPMA of the cross section of the diffusion layer of the material of the present invention which has been subjected to the heat diffusion treatment for 30 minutes.

The heat-resistant hardness in Table 1 is the result of measuring the Vickers hardness (Hv) after heating and diffusion treatment at 350°C for 5 minutes, and the corrosion test was conducted using salt water spray for 1 hour based on Its 22371. Thereafter, an operation of holding the sample in a constant temperature and humidity chamber at a temperature of 70° C. and a humidity of 95% RH for 23 hours was repeated 3θ times.

It was processed to obtain a strip with a thickness of 0.065 mm.

Both sides of these strips were plated with either Zn-Ni or Zn-8 layer alloy plating with the composition shown in Table 3 using plating bath (1) or (2) shown in Table 2 to a thickness of 2.4 μm on one side. One side 71 by coating or hot dip method
After forming the Zn-10%A1 alloy film in μm, 500 μm
℃ x 1 minute, and then rolled to obtain a strip with a thickness of 0036 mm (N (114 ~ N (125)).
was manufactured.

The heat-resistant hardness and electrical conductivity of these were measured, and tests similar to the corrosion test described above were conducted to measure the deterioration rate of tensile strength and to evaluate the degree of dezincing by observing the appearance. These results were then applied to the substrate after plating pure Zn with a thickness of 2.4 μm on one side in the plating bath (3) at 450°C.
Comparison strips (Oka 26 to Nα28) with a thickness of 0.036 m obtained by heating and diffusion treatment for ×1 minute and then rolling.
The measurement results after the corrosion test are shown in Table 3 (J).

As is clear from Table 1, the comparative strip layers 11 to 13 plated with pure Zn had significant surface dezincing and significant strength deterioration due to corrosion. On the other hand, the strip material Nα1 of the present invention
~Nα7 showed slight dezincing after the corrosion test, indicating that strength deterioration was small and corrosion resistance was improved.

Furthermore, although the strip materials Nα1 to Nn1 of the present invention are excellent in both heat resistance and electrical conductivity as well as the above-mentioned corrosion resistance, comparative examples Nα8 to Nα in which the chemical composition of the base material strip is outside the specified range.
It can be seen that the sample with a rating of 10 is inferior in either heat resistance or electrical conductivity.

Furthermore, as is clear from FIG. 1, the Zn diffusion layer (a) formed on the surface layer of the strip of the present invention plated with Zn-Ni alloy is similar to the Cu-Zn-Ni alloy diffusion layer (
It can be seen that it consists of two layers: b) and a Cu-Zn alloy diffusion layer (cl) inside it.

Example (2) An ingot having the composition shown in Table 3, which has the same composition as the ingot cast in Example (1), was used as the strip material of the present invention as in Example (1), as is clear from Table 3. Nα14-22 has excellent corrosion resistance as well as heat resistance and electrical conductivity, but comparison strip materials Ma23-Nα2 have chemical components of the base material that are outside the specified range.
At 5, either heat resistance or conductivity is poor, and at 10
It can be seen that all of the comparison strips 2G to Nα28, which were subjected to 0% Zn plating, had decreased corrosion resistance.

Example (3) Thickness 0. [A plating bath shown in Table 2 was applied to a heat-resistant copper strip (conductivity 95.5% 1^C8) containing 1% M g O,02v of 135+ nm as shown in Table 4 to a thickness of 1.
The same corrosion test as in Example (1) was conducted on the strip of the present invention, which had been plated with 2 pm of Zn-Ni or Zn-3n alloy on both sides and then heated and diffused at 350°C for 30 minutes. The rate of strength deterioration was measured. The results are shown in Table 4 in comparison with a comparative strip material plated with 1.2 μm thick pure Zn using plating bath (3) in Table 2 and subjected to heat diffusion treatment at 350°C for 30 minutes. Ta.

As is clear from Table 4, the comparative strip material Ma31 plated with pure Zn has little strength deterioration due to corrosion, whereas the present invention strip materials Nα29 to 30 have little strength deterioration and improved corrosion resistance. I know that there is.

Example (4) Next, MgO,Q2wf with a thickness of 0.065ffllTI
Heat-resistant copper strip (conductivity 95.5% IACS) containing 96,
Using the above plating bath (1+ and (2), 2.4
After plating Zn-Ni alloy or Zn-3n alloy to a thickness of μm, heat expansion treatment was performed at 500°C for 1 minute, and this was rolled to a thickness of 0.036 mm (Nt13
2, Nα33).

Furthermore, Zn-! with a thickness of 4 μm was applied to the heat-resistant copper strip with a thickness of 0.065 mm by the hot dip method. After forming a 0% Al alloy film, it was heated and diffused at 500°C for 1 minute, and then rolled to form a strip of the present invention (N1) with a thickness of 0.036 mm.
134).

These were subjected to the same corrosion test as above to measure the deterioration rate of tensile strength. The results are shown in Table 2.
After performing pure Zn plating with a thickness of 2.4 μm in step 3), heat diffusion treatment was performed at 450”CX for 1 minute, and after that, a comparative strip material was rolled to a thickness of 0.036 mm (
A comparison with Nα35) is shown in Table 5.

As is clear from Table 5, the comparison strip Nα35, which was obtained by plating with pure Zn and then heating diffusion and rolling, had significant Zn removal and significant strength deterioration, whereas the present invention strip Nα32~ It can be seen that No. 34 has less dezincing and less strength deterioration.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to effectively improve the corrosion resistance of copper-based heat exchanger fin materials and other system control materials, and to suppress the decrease in thermal conductivity. This has significant industrial effects, such as making it possible to make heat exchanger fin materials thinner and lighter.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of line analysis by EPMA in a cross section of a diffusion layer of a strip of the present invention. a...Zn diffusion layer

Claims (24)

[Claims] (1) An inner diffusion layer made of Cu and Zn was formed on the surface layer of Cu or Cu alloy, and a surface side diffusion layer made of Cu, Zn, and an element whose diffusion coefficient into Cu is smaller than that of Zn was formed on the surface side. A copper-based material with excellent thermal conductivity and corrosion resistance. (2) Copper with excellent thermal conductivity and corrosion resistance according to claim (1), wherein one or more of Ni, Co, Sn, and Al is used as the element whose diffusion coefficient into Cu is smaller than that of Zn. system material. (3) After forming an alloy film consisting of Zn and an element whose diffusion coefficient into Cu is smaller than that of Zn on the surface of Cu or Cu alloy, heat diffusion treatment is performed to infuse Cu and Zn onto the surface layer of Cu or Cu alloy. An inner diffusion layer consisting of Cu and Cu on the surface side.
A method for producing a copper-based material having excellent thermal conductivity and corrosion resistance, characterized by forming a surface-side diffusion layer consisting of an element having a smaller diffusion coefficient into Zn and Cu than Zn. (4) Copper with excellent thermal conductivity and corrosion resistance according to claim (3), wherein one or more of Ni, Co, Sn, and Al is used as the element whose diffusion coefficient into Cu is smaller than that of Zn. Methods for manufacturing system materials. (5) After forming an alloy film consisting of Zn and an element whose diffusion coefficient into Cu is smaller than that of Zn on the surface of Cu or Cu alloy, heat diffusion treatment is performed to infuse Cu and Zn onto the surface layer of Cu or Cu alloy. An inner diffusion layer consisting of Cu and Cu on the surface side.
A copper-based material with excellent thermal conductivity and corrosion resistance, which is characterized by forming a surface-side diffusion layer consisting of an element whose diffusion coefficient into Zn and Cu is smaller than that of Zn, and then subjecting it to rolling or wire drawing. Method of manufacturing the material. (6) Copper with excellent thermal conductivity and corrosion resistance according to claim (5), wherein one or more of Ni, Co, Sn, and Al is used as the element whose diffusion coefficient into Cu is smaller than that of Zn. Methods for manufacturing system materials. (7) An inner diffusion layer made of Cu and Zn was formed on the surface layer of Cu or Cu alloy, and a surface side diffusion layer made of Cu, Zn, and an element whose diffusion coefficient into Cu is smaller than that of Zn was formed on the surface side. A fin material for heat exchangers characterized by: (8) The fin material for a heat exchanger according to claim A (7), in which one or more of Ni, Co, Sn, and Al is used as the element whose diffusion coefficient into Cu is smaller than that of Zn. (9) After forming an alloy film consisting of Zn and an element whose diffusion coefficient into Cu is smaller than that of Zn on the surface of Cu or Cu alloy, heat diffusion treatment is performed to infuse Cu and Zn onto the surface layer of Cu or Cu alloy. An inner diffusion layer consisting of Cu and Cu on the surface side.
A method for manufacturing a fin material for a heat exchanger, characterized in that a surface side diffusion layer is formed of an element whose diffusion coefficient into Zn and Cu is smaller than that of Zn. (10) The method for producing a fin material for a heat exchanger according to (9), wherein one or more of Ni, Co, Sn, and Al is used as the element whose diffusion coefficient into Cu is smaller than that of Zn. (11) After forming an alloy film consisting of Zn and an element whose diffusion coefficient into Cu is smaller than that of Zn on the surface of Cu or Cu alloy, heat diffusion treatment is performed to infuse Cu and Zn onto the surface layer of Cu or Cu alloy. and an inner diffusion layer consisting of C on the surface side.
A method for manufacturing a fin material for a heat exchanger, comprising forming a surface-side diffusion layer consisting of elements having a diffusion coefficient smaller than that of Zn into u, Zn, and Cu, and then subjecting the layer to a rolling process. (12) The method for producing a fin material for a heat exchanger according to claim (11), wherein one or more of Ni, Co, Sn, and Al is used as the element whose diffusion coefficient into Cu is smaller than that of Zn. (13) Mg, Zn, Sn, Cd, Ag, Ni, P, Z
A heat-resistant copper strip containing a total of 0.01 to 0.13 wt% of one or more of r, Cr, Pb, and Al, with the remainder being Cu and having an electrical conductivity of 90% IACS or higher. A copper-based material with excellent thermal conductivity and corrosion resistance, characterized by having an inner diffusion layer formed on the inner side diffusion layer, and a surface side diffusion layer made of Cu, Zn, and an element whose diffusion coefficient into Cu is smaller than that of Zn on the surface side. material. (14) The copper with excellent thermal conductivity and corrosion resistance according to claim (13), wherein one or more of Ni, Co, Sn, and Al is used as the element whose diffusion coefficient into Cu is smaller than that of Zn. system material. (15) Mg, Zn, Sn, Cd, Ag, Ni, P, Z
The heat-resistant copper strip surface contains one or more of r, Cr, Pb, and Al in a total of 0.01 to 0.13 wt%, and the balance is Cu, and the conductivity is 90% IACS or higher. After forming an alloy film consisting of Zn and an element whose diffusion coefficient is smaller than that of Zn, a heating diffusion treatment is performed to form an inner diffusion layer consisting of Cu and Zn on the surface layer of Cu or Cu alloy, and an inner diffusion layer consisting of Cu and Zn on the surface side. A method for manufacturing a copper-based material having excellent thermal conductivity and corrosion resistance, which comprises forming a surface-side diffusion layer made of an element having a diffusion coefficient into Cu smaller than that of Zn. (16) The copper with excellent thermal conductivity and corrosion resistance according to claim (15), wherein one or more of Ni, Co, Sn, and Al is used as the element whose diffusion coefficient into Cu is smaller than that of Zn. Methods for manufacturing system materials. (17) Mg, Zn, Sn, Cd, Ag, Ni, P, Z
The heat-resistant copper strip surface contains one or more of r, Cr, Pb, and Al in a total of 0.01 to 0.13 wt%, and the balance is Cu, and the conductivity is 90% IACS or higher. After forming an alloy film consisting of Zn and an element whose diffusion coefficient is smaller than that of Zn, a heating diffusion treatment is performed to form an inner diffusion layer consisting of Cu and Zn on the surface layer of Cu or Cu alloy, and an inner diffusion layer consisting of Cu and Zn on the surface side. Production of a copper-based material with excellent thermal conductivity and corrosion resistance, characterized by forming a surface-side diffusion layer made of an element whose diffusion coefficient into Cu is smaller than that of Zn, and then subjecting it to rolling or wire drawing. Method. (18) The copper with excellent thermal conductivity and corrosion resistance according to claim (17), wherein one or more of Ni, Co, Sn, and Al is used as the element whose diffusion coefficient into Cu is smaller than that of Zn. Methods for manufacturing system materials. (19) Mg, Zn, Sn, Cd, Ag, Ni, P, Z
A heat-resistant copper strip containing a total of 0.01 to 0.13 wt% of one or more of r, Cr, Pb, and Al, with the remainder being Cu and having an electrical conductivity of 90% IACS or higher. 1. A fin material for a heat exchanger, comprising: an inner diffusion layer; and a surface-side diffusion layer made of Cu, Zn, and an element whose diffusion coefficient into Cu is smaller than that of Zn. (20) The fin material for a heat exchanger according to claim (19), wherein one or more of Ni, Co, Sn, and Al is used as the element whose diffusion coefficient into Cu is smaller than that of Zn. (21) Mg, Zn, Sn, Cd, Ag, Ni, P, Z
The heat-resistant copper strip surface contains one or more of r, Cr, Pb, and Al in a total of 0.01 to 0.13 wt%, and the balance is Cu, and the conductivity is 90% IACS or higher. After forming an alloy film consisting of Zn and an element whose diffusion coefficient is smaller than that of Zn, a heating diffusion treatment is performed to form an inner diffusion layer consisting of Cu and Zn on the surface layer of Cu or Cu alloy, and an inner diffusion layer consisting of Cu and Zn on the surface side. A method for manufacturing a fin material for a heat exchanger, characterized in that a surface-side diffusion layer is formed of an element whose diffusion coefficient into Cu is smaller than that of Zn. (22) The method for producing a fin material for a heat exchanger according to claim (21), wherein one or more of Ni, Co, Sn, and Al is used as the element whose diffusion coefficient into Cu is smaller than that of Zn. (23) Mg, Zn, Sn, Cd, Ag, Ni, P, Z
The heat-resistant copper strip surface contains one or more of r, Cr, Pb, and Al in a total of 0.01 to 0.13 wt%, and the balance is Cu, and the conductivity is 90% IACS or higher. After forming an alloy film consisting of Zn and an element whose diffusion coefficient is smaller than that of Zn, a heating diffusion treatment is performed to form an inner diffusion layer consisting of Cu and Zn on the surface layer of Cu or Cu alloy, and an inner diffusion layer consisting of Cu and Zn on the surface side. A method for manufacturing a fin for a heat exchanger, comprising forming a surface-side diffusion layer made of an element whose diffusion coefficient into Cu is smaller than that of Zn, and then subjecting it to rolling. (24) The method for producing a fin material for a heat exchanger according to claim (23), wherein one or more of Ni, Co, Sn, and Al is used as the element whose diffusion coefficient into Cu is smaller than that of Zn.