JP5226057B2 - Copper alloys, copper products, electronic components and connectors - Google Patents

Description

  The present invention relates to a copper alloy, a rolled copper product, an electronic component, and a connector.

  In recent years, electronic devices typified by portable terminals and the like have been increasingly miniaturized, and accordingly, connectors used for such devices tend to have a narrow pitch and a low profile. The smaller the connector, the narrower the pin width and the smaller the folded shape, so the material used has high strength to obtain the necessary spring properties and excellent bending workability that can withstand severe bending work. Desired.

  In this regard, a copper alloy containing titanium (hereinafter referred to as “titanium copper”) has a relatively high strength and the best stress relaxation characteristics among copper alloys. It has been used for a long time as a signal system terminal material. Titanium copper is an age-hardening type copper alloy. Specifically, when a supersaturated solid solution of Ti, which is a solute atom, is formed by solution treatment, and heat treatment is performed at a low temperature for a relatively long time from that state, periodic fluctuations in Ti concentration in the parent phase due to spinodal decomposition The modulation structure is developed and the strength is improved. Based on this strengthening mechanism, various methods have been studied with the aim of further improving the properties of titanium copper.

  At this time, the problem is that the strength and the bending workability are contradictory. That is, if the strength is improved, the bending workability is impaired, and conversely, if the bending workability is emphasized, a desired strength cannot be obtained. Therefore, a third element such as Fe, Co, Ni, Si or the like is added (Patent Document 1), the concentration of the impurity element group that dissolves in the matrix phase is regulated, and these elements are added to the second phase particles (Cu-Ti- X-type particles) are precipitated in a predetermined distribution form to increase the regularity of the modulation structure (Patent Document 2), and the density of the trace additive elements and second-phase particles effective to refine the crystal grains is specified. From the viewpoints of (Patent Document 3), etc., research and development have been made in order to achieve both the strength and bending workability of titanium copper.

  Patent Document 1 describes that titanium copper having a maximum 0.2% proof stress of 888 MPa was obtained, and MBR / t at this time was 0.7 (Example No. 10). Patent Document 2 describes that titanium copper having a maximum 0.2% proof stress of 839 MPa was obtained, and MBR / t at this time was 1.7 (Example No. 10). Patent Document 3 describes that titanium copper having a maximum 0.2% proof stress of 888 MPa was obtained, and MBR / t at this time was 0.5 (Example No. 10).

Further, in Patent Document 4, in the case of titanium copper, there exists a β phase (TiCu ₃ ) having poor consistency with the α phase as a parent phase and a β ′ phase (TiCu ₄ ) having good consistency, and the β phase Titanium with finely dispersed β 'phase while suppressing β phase, while having an adverse effect on bendability, and that uniform and finely dispersing β' phase contributes to both strength and bending workability Copper is disclosed. Patent Document 4 describes that titanium copper having a maximum 0.2% proof stress of 1019 MPa was obtained, and MBR / t at this time was 2 (Example No. 4).

Also, in these documents, titanium copper is manufactured in the order of melting casting of ingot → homogenization annealing → hot rolling → (repetition of annealing and cold rolling) → final solution treatment → cold rolling → aging treatment. It is described. In particular, in the final solution treatment, it is important to suppress the precipitation of second phase particles that are inconsistent with the stable phase of TiCu ₃ or the parent phase.

Japanese Patent Laid-Open No. 2004-231985 JP 2004-176163 A JP-A-2005-97638 JP 2006-283142 A

  In this way, titanium copper is generally manufactured in the order of melt casting of ingot → homogenization annealing → hot rolling → (repetition of annealing and cold rolling) → final solution treatment → cold rolling → aging treatment. The improvement of the characteristics has been attempted on the basis of this process. However, it is useful to find a new manufacturing method that is not bound by the existing concept in obtaining titanium copper having superior characteristics.

  Therefore, the main object of the present invention is to provide a new copper alloy, copper-drawn product, electronic component, and connector that can improve the characteristics of titanium copper.

  In the conventional titanium copper manufacturing method, titanium is sufficiently dissolved in the matrix by the final solution treatment, then cold rolled to increase the strength to a certain extent, and finally spinodal decomposition is caused by aging treatment. High strength titanium copper was obtained. For this reason, it has not been considered to carry out a heat treatment before the cold rolling, in which a stable phase of titanium that has been dissolved in a solid solution may precipitate.

  However, as a result of diligent research, the present inventor has caused spinodal decomposition to some extent before cold rolling by heat treatment to such an extent that the metastable phase or stable phase of titanium does not form or partially forms. It has been found that the strength of titanium copper finally obtained by performing cold rolling and aging treatment is significantly improved. That is, while the conventional titanium copper production method performs the heat treatment step causing spinodal decomposition in one stage of aging treatment, the titanium copper production method of the present invention performs the conventional aging treatment after the final solution treatment. The heat treatment is performed in a time shorter than the treatment and under the condition of sub-aging, followed by cold rolling, and further performing a two-stage aging treatment in which a lighter aging treatment is performed after the cold rolling. This is very different from the conventional method.

  Furthermore, it was also found that titanium copper having a significantly improved balance between strength and bending workability can be obtained by performing an aging treatment on the low temperature side as compared with the prior art after adding a heat treatment step.

  The reason why the characteristics of titanium copper have been improved by adopting the above manufacturing process has not been sufficiently elucidated. Although not intended to limit the invention by theory, this is presumed as follows. In titanium copper, as the titanium modulation structure develops in the aging treatment, the amplitude of the titanium concentration change (light and shade) increases, but when it reaches a certain amplitude, near the peak where it can no longer withstand fluctuations The titanium changes to a more stable β ′ phase and further to a β phase. That is, titanium dissolved in the mother phase by solution treatment gradually develops a modulation structure, which is a periodic variation of Ti concentration, by applying heat treatment thereafter, and this is a metastable phase β 'Change to phase, and finally to β phase, which is a stable phase. However, after the final solution treatment and before cold rolling, if a predetermined heat treatment that can cause spinodal decomposition is performed in advance, the β ' It is considered that the crystal has grown to a modulation structure having a larger amplitude. And it is thought that such a large modulation structure of fluctuation gave the titanium copper a stickiness. However, it is technically difficult to measure the amplitude of the titanium concentration, and details of the mechanism for improving the characteristics have not been clarified. In any case, by adopting the manufacturing method of the present invention, it becomes possible to obtain titanium copper having a higher strength than the conventional manufacturing method in which spinodal decomposition is performed only in one stage.

The present invention completed based on the above, in one aspect, contains 2.0 to 4.0% by mass of Ti, and Mn, Fe, Mg, Co, Ni, Cr, V, Nb, Mo, Zr as the third element. , Si, B, P containing a total of 0 to 0.5% by mass of copper alloy consisting of the remaining copper and unavoidable impurities, and an electron microscope of the surface after electrolytic polishing of the rolled surface In the structure observation, the number density (X) of the second phase particles having a particle size of 0.5 μm or more is 0.04 to 0.11 particles / μm ² and the second phase particles having a particle size of 0.5 μm or more are particles. It is a copper alloy that the number ratio (Y) deposited along the boundary is 45 to 80%.

The copper alloy according to the present invention is subjected to a solution treatment that is rapidly cooled by heating until a temperature higher by 0 to 20 ° C. than a solid solubility limit temperature at which the solid solubility limit of Ti becomes the same as the addition amount at 550 to 1000 ° C. When the titanium concentration (mass%) is [Ti] following the solution treatment, the conductivity increase value C (% IACS) is expressed by the following relational expression: 0.5 ≦ C ≦ (−0. 50 [Ti] ² −0.50 [Ti] +14), a heat treatment for increasing the electrical conductivity is performed, the final cold rolling is performed following the heat treatment, and the aging treatment is performed following the final cold rolling. It is manufactured by.

  In another aspect, the present invention is a copper drawn product using the above copper alloy.

  In still another aspect of the present invention, an electronic component manufactured using the copper alloy is provided.

  In still another aspect, the present invention provides a connector manufactured using the copper alloy.

  According to the present invention, the strength of titanium copper can be improved. Moreover, in preferable embodiment of this invention, the titanium copper which can achieve intensity | strength and bending workability in a high dimension is obtained.

1 (a) and 1 (b) are schematic diagrams for explaining a method of measuring second phase particles appearing on a rolled surface after electrolytic polishing of titanium copper according to an embodiment of the present invention.

If the Ti content Ti is less than 2% by mass, a sufficient strengthening mechanism cannot be obtained due to the formation of the original modulation structure of titanium copper. On the contrary, if the Ti content exceeds 4% by mass, coarse TiCu ₃ Tends to precipitate, and the strength and bending workability tend to deteriorate. Therefore, the content of Ti in the copper alloy according to the present invention is 2.0 to 4.0 mass%, preferably 2.7 to 3.5 mass%. Thus, by optimizing the Ti content, both strength and bending workability suitable for electronic components can be realized.

Third Element Since the third element contributes to the refinement of crystal grains, a predetermined third element can be added. Specifically, even if the solution treatment is performed at a high temperature at which Ti is sufficiently dissolved, the crystal grains are easily refined and the strength is easily improved. The third element also promotes the formation of the modulation structure. Furthermore, there is an effect of suppressing precipitation of TiCu ₃ . Therefore, the original age hardening ability of titanium copper can be obtained.

  In titanium copper, Fe has the highest effect. And in Mn, Mg, Co, Ni, Si, Cr, V, Nb, Mo, Zr, B, and P, the effect according to Fe can be expected, and even if added alone, the effect is seen, but two or more Multiple additions may be made.

  When these elements contain a total of 0.05% by mass or more, the effect appears. However, when the total exceeds 0.5% by mass, the solid solubility limit of Ti is narrowed and coarse second-phase particles are precipitated. It becomes easy and the strength is slightly improved, but the bending workability deteriorates. At the same time, the coarse second-phase particles promote roughening of the bent portion and promote die wear during press working. Accordingly, the total of one or more selected from the group consisting of Mn, Fe, Mg, Co, Ni, Cr, V, Nb, Mo, Zr, Si, B, and P as the third element group is 0 to 0 in total. It can contain 0.5 mass%, and it is preferable to contain 0.05-0.5 mass% in total.

  A more preferable range of these third elements is 0.17 to 0.23 mass% in Fe, and 0.15 to 0.25 mass in Co, Mg, Ni, Cr, Si, V, Nb, Mn, and Mo. %, Zr, B, and P are 0.05 to 0.1% by mass.

Second Phase Particle In the present invention, “second phase particle” refers to a particle having a composition different from the component composition of the parent phase. The second-phase particles are particles mainly composed of Cu and Ti that precipitate during various heat treatments to form a boundary with the parent phase. Specifically, TiCu ³ particles or a constituent element X (third element group X ( Specifically, it appears as Cu—Ti—X-based particles containing Mn, Fe, Mg, Co, Ni, Cr, V, Nb, Mo, Zr, Si, B, and P).

By observing the precipitation state of the second phase particles, the degree of material strengthening by spinodal decomposition can be indirectly evaluated. In the present embodiment, the number density (X) of second phase particles having a particle size of 0.5 μm or more is 0.04 to 0.11 particles / μm ^{2 in the} observation of the structure of the surface after electrolytic polishing of the rolled surface by an electron microscope. It is suitable for appropriately developing a modulation structure by spinodal decomposition to obtain a good balance between strength and bending workability, more preferably 0.04 to 0.10 pieces / μm ² , and still more preferably. Is 0.05 to 0.09 / μm ² . If the number density (X) is less than 0.04 / μm ² , the strength (YS) may be insufficient, and if the number density (X) is more than 0.11 / μm ² , bending workability is poor. In some cases, it is not possible to achieve both strength and bending workability.

  Moreover, in the titanium copper according to the present embodiment, it is appropriate that the number ratio (Y) of grain boundary precipitation of the second phase particles having a particle size of 0.5 μm or more is 45 to 80%, more preferably 50 to 50%. 78%, more preferably 59 to 71%. If the number ratio (Y) is lower than 45%, the strength (YS) may be insufficient, and if the number ratio (Y) is higher than 80%, the bending workability (MBR / t) may deteriorate. In some cases, it is impossible to achieve both strength and bending workability.

In the present embodiment, the diameter of the second phase particles is the diameter of the largest circle inscribed in the second phase particles when the surface of the rolled surface after electropolishing is observed with an electron microscope (see FIG. 1 (a)). We will define as That is, the “second phase particle having a particle size of 0.5 μm or more” refers to a particle having a maximum circle diameter (see FIG. 1A) inscribed in the second phase particle of 0.5 μm or more. Moreover, the following calculation method is employ | adopted regarding the calculation method of the number of the particles at the time of evaluating number density (X). That is, among the second phase particles having a particle size of 0.5 μm or more dispersed in the observation field,
(A) For second phase particles having a particle size of 0.5 μm or more and less than 1.0 μm (a) The diameter of the smallest circle circumscribing the second phase particles (see FIG. 1A) is 0.5 μm or more and 1.0 μm. Particles less than “1”
(B) Particles having a diameter of the smallest circle circumscribing the second phase particles (see FIG. 1A) of 1.0 μm or more: “two”
Count as
(B) For second-phase particles with a particle size of 1.0 μm or more, when a mesh with an interval of 0.5 μm is applied to the observation field, the particle part surrounded by 0.5 μm square is “one”, exceeding the mesh The portion of the particles protruding outside 0.5 μm square is calculated as “1/2” (see FIG. 1B).

Regarding the “number ratio (Y) of grain boundary precipitation of second phase particles having a particle size of 0.5 μm or more”, among the second phase particles having a particle size of 0.5 μm or more dispersed in the observation field counted in the above procedure The number of particles existing along the grain boundary was calculated. A crystal grain boundary is defined as an interface having a different contrast by using a reflected electron image obtained by SEM observation, and the method for calculating the number of particles is the same as the method for calculating the number density (X).

Manufacturing method of copper alloy according to the present invention The copper alloy according to the present invention can be manufactured by making a predetermined modification to a known manufacturing method of titanium copper as described in Patent Documents 1 to 4 described above. . That is, after the final solution treatment, heat treatment capable of causing spinodal decomposition is performed in advance before cold rolling.

  In the conventional titanium copper manufacturing method, titanium is sufficiently dissolved in the matrix by the final solution treatment, then cold rolled to increase the strength to a certain extent, and finally spinodal decomposition is caused by aging treatment. Thus, high strength titanium copper is obtained. Therefore, the final aging treatment is important, and it is important that the final solution treatment sufficiently dissolves titanium in the matrix and causes maximum spinodal decomposition at an appropriate temperature and time in the aging treatment. It was. If the temperature is too low and the time is too short, the development of the modulation structure caused by spinodal decomposition tends to be insufficient in the aging treatment, and the modulation structure generated by the spinodal decomposition grows by increasing the temperature and the time, so that an appropriate bending is achieved. Strength increases while maintaining processability. However, if the temperature of the material is too high and too long, the β ′ phase that does not contribute much to the strength and the β phase that deteriorates the bending workability tend to precipitate, and the strength is not increased or the strength is decreasing. , Bending workability deteriorates.

  On the other hand, in the present invention, after the final solution treatment, heat treatment is performed and spinodal decomposition is caused in advance, and thereafter, conventional cold rolling, conventional level aging treatment or aging treatment at a lower temperature and shorter time is performed. To increase the strength of titanium copper. That is, according to the alloy composition of titanium copper, the heat treatment is not performed up to the treatment condition in which the hardness reaches the peak, but the heat treatment is terminated at a previous stage (under the condition of subaging). . When the titanium copper after solution treatment is heat-treated, the conductivity increases with the progress of spinodal decomposition, so in the present invention, an appropriate degree of heat treatment is defined by using the change in conductivity before and after the heat treatment as an index. did. According to the inventor's research, the heat treatment is preferably performed under the condition that the conductivity is increased by 0.5 to 8% IACS. Note that there is no problem as long as a small amount of β ′ phase or β phase is precipitated, but if it is precipitated in a large amount, the effect of improving the strength intended by the present invention cannot be obtained, or even if the strength is high, the loss workability is remarkably deteriorated. More preferably, it is desirable to carry out under conditions that raise IACS by 1 to 4%. Specific heating conditions corresponding to such an increase in electrical conductivity are conditions of heating for 0.001 to 12 hours at a material temperature of 300 to 700 ° C.

The appropriate degree of increase in electrical conductivity due to sub-aging is specified as follows. That is, in the heat treatment according to the present embodiment, when the titanium concentration (% by mass) is [Ti], the increase value C (% IACS) of the conductivity can satisfy the following relational expression (1).
0.5 ≦ C ≦ (−0.50 [Ti] ² −0.50 [Ti] +14) (1)
According to the above formula (1), for example, when the Ti concentration is 2.0% by mass, it is desirable that the conductivity be increased by 0.5 to 11% IACS, and the Ti concentration is 3.0% by mass. In this case, it is desirable that the conductivity be increased by 0.5 to 8% IACS. When the Ti concentration is 4.0% by mass, the conductivity is increased by 0.5 to 4% IACS. It is desirable to carry out under conditions.

More preferably, in the heat treatment according to the present embodiment, when the titanium concentration (% by mass) is [Ti], the increase C in conductivity (% IACS) satisfies the following relational expression (2). .
1.0 ≦ C ≦ (0.25 [Ti] ² −3.75 [Ti] +13) (2)
According to the above formula (2), for example, when the Ti concentration is 2.0% by mass, it is desirable that the conductivity be increased by 1.0 to 6.5% IACS, and the Ti concentration is 3.0%. In the case of mass%, it is desirable to carry out under conditions that increase the conductivity by 1.0 to 4% IACS, and in the case of Ti concentration of 4.0 mass%, the conductivity is increased by 1.0 to 2% IACS. It is desirable to carry out under such conditions.

  In addition, when the aging at which the hardness of the copper alloy reaches a peak is performed in the heat treatment after the final solution treatment, the difference in conductivity is, for example, 13% IACS and Ti concentration of 3.0% at a Ti concentration of 2.0% by mass. Thus, 10% IACS and Ti concentration of 4.0% increase by about 5% IACS. That is, in the heat treatment after the final solution treatment according to the present embodiment, the amount of heat given to the copper alloy is much smaller than the aging at which the hardness reaches a peak. In the heat treatment according to the present embodiment, high-strength titanium copper can be produced by performing the heat treatment at a high temperature (for example, 400 ° C. or more) for a short time (0.5 hours or less).

Therefore, the heat treatment is preferably performed under any of the following conditions.
-Heating at a material temperature of 300 ° C or more and less than 400 ° C for 0.5 to 12 hours · Heating at a material temperature of 400 ° C or more and less than 500 ° C for 0.01 to 0.5 hours Heating for 0.01 hours-Heating for 0.001 to 0.005 hours at a material temperature of 600 ° C or higher and lower than 700 ° C

The heat treatment is more preferably performed under any of the following conditions.
-Heating at a material temperature of 400 ° C to less than 450 ° C for 0.25 to 0.5 hours · Heating at a material temperature of 450 ° C to less than 500 ° C for 0.01 to 0.25 hours Heating from 0.00 to 0.0075 hours at a material temperature of 550 ° C. or more and less than 600 ° C. Heating at a material temperature of from 600 ° C. to less than 650 ° C. for 0.0025 to 0.005 hours

Hereinafter, a preferred embodiment will be described for each process.
1) Ingot manufacturing process Manufacturing of an ingot by melting and casting is basically performed in a vacuum or in an inert gas atmosphere. If the additive element remains undissolved during melting, it does not effectively act on strength improvement. Therefore, in order to eliminate undissolved residue, it is necessary to add a high-melting-point additive element such as Fe or Cr, and after stirring sufficiently, hold it for a certain period of time. On the other hand, since Ti is relatively easily dissolved in Cu, it may be added after the third element group is dissolved. Therefore, Cu includes one or more selected from the group consisting of Mn, Fe, Mg, Co, Ni, Cr, V, Nb, Mo, Zr, Si, B, and P in total from 0 to 0.0. It adds so that it may contain 50 mass%, and then adds Ti so that it may contain 2.0-4.0 mass%, and manufactures an ingot.

2) Homogenization annealing and hot rolling Here, it is desirable to eliminate solidified segregation and crystallized substances generated during casting as much as possible. This is because, in the subsequent solution treatment, the precipitation of the second phase particles is finely and uniformly dispersed, which is effective in preventing mixed grains.
After the ingot manufacturing process, it is preferable to perform hot rolling after heating to 900 to 970 ° C. and performing homogenization annealing for 3 to 24 hours. In order to prevent liquid metal brittleness, it is preferable that the temperature is 960 ° C. or less before and during hot rolling, and that the pass from the original thickness to 90% of the overall workability is 900 ° C. or more. And in order to raise | generate moderate recrystallization for every pass and to reduce the segregation of Ti effectively, it is good to implement the amount of rolling reduction for every pass at 10-20 mm.

3) First solution treatment It is then preferable to perform the solution treatment after appropriately repeating cold rolling and annealing. The reason why the solution treatment is performed in advance is to reduce the burden in the final solution treatment. That is, in the final solution treatment, it is not a heat treatment for dissolving the second phase particles, but is already in solution, so it is only necessary to cause recrystallization while maintaining that state. Just heat treatment. Specifically, the first solution treatment may be performed at a heating temperature of 850 to 900 ° C. for 2 to 10 minutes. It is preferable to increase the heating rate and cooling rate at that time as much as possible so that the second phase particles do not precipitate.

4) Intermediate rolling As the degree of processing in the intermediate rolling before the final solution treatment is increased, the second phase particles in the final solution treatment are precipitated more uniformly and finely. However, if the final solution treatment is performed with a too high degree of processing, a recrystallized texture develops and plastic anisotropy occurs, which may impair the press formability. Therefore, the processing degree of intermediate rolling is preferably 70 to 99%. The degree of work is defined by {((thickness before rolling−thickness after rolling) / thickness before rolling) × 100%}.

5) Final solution treatment In the final solution treatment, it is desirable to completely dissolve the precipitate. However, when heated to a high temperature until it completely disappears, the crystal grains become coarse, so the heating temperature is the second phase. The temperature is around the solid solubility limit of the particle composition (the temperature at which the solid solubility limit of Ti becomes equal to the addition amount in the range of 2.0 to 4.0% by mass of Ti (solid solubility limit temperature) is 730 to For example, it is about 800 ° C. when the amount of Ti added is 3.0% by mass). And if it heats rapidly to this temperature and a cooling rate is also made fast, generation | occurrence | production of coarse 2nd phase particle | grains will be suppressed. Although not limited to the following conditions, typically, the copper alloy material before solution treatment is 0 to 20 ° C higher than the solid solution limit temperature of Ti at 550 to 1000 ° C, preferably 0. It can heat up to a temperature higher by 10 ° C. Further, the shorter the heating time at the solid solution temperature, the finer the crystal grains. Therefore, it is preferable to heat the material at a temperature at which the solid solubility limit of Ti at 550 to 1000 ° C. is larger than the addition amount for 0.5 to 3 minutes and then water-cool.

6) Heat treatment Heat treatment is performed after the final solution treatment. The conditions for the heat treatment are as described above.

7) Final cold rolling After the heat treatment, final cold rolling is performed. The strength of titanium copper can be increased by the final cold working. At this time, if the degree of work is less than 10%, a sufficient effect cannot be obtained. However, the higher the degree of work, the more likely grain boundary precipitation occurs in the next aging treatment, so the degree of work is 50% or less, more preferably 25% or less.

8) Aging treatment An aging treatment is performed after the final cold rolling. The conditions for the aging treatment may be conventional conditions, but if the aging treatment is performed lighter than the conventional one, the balance between strength and bending workability is further improved. Specifically, the aging treatment is preferably performed under the condition of heating at a material temperature of 290 to 400 ° C. for 3 to 12 hours. When aging is not performed, when the aging treatment time is short (less than 2 hours), or when the aging treatment temperature is low (less than 290 ° C.), strength and conductivity may be reduced. Further, when the aging time is long (13 hours or longer) or when the aging temperature is high (450 ° C. or higher), the electrical conductivity increases, but the strength may decrease.

The aging treatment is more preferably performed under any of the following conditions.
-Heat for 7 to 12 hours at a material temperature of 290 ° C to less than 320 ° C · Heat for 6 to 11 hours at a material temperature of 320 ° C to less than 340 ° C · Heat for 5 to 8 hours at a material temperature of 340 ° C to less than 360 ° C · Material temperature of 360 ° C Heat for less than 400 ° C for 2-7 hours

It is even more preferable that the aging treatment is performed under any of the following conditions.
-Material temperature 290 ° C or higher and lower than 320 ° C for 8 to 11 hours · Material temperature 320 ° C or higher and lower than 340 ° C for 7 to 10 hours · Material temperature 340 ° C or higher and lower than 360 ° C for 6 to 7 hours · Material temperature 360 ° C Heat for less than 400 ° C for 3-7 hours

  A person skilled in the art will understand that steps such as grinding, polishing, and shot blast pickling for removing oxide scale on the surface can be appropriately performed between the above steps.

Characteristics of Copper Alloy According to the Present Invention In one embodiment, the copper alloy obtained by the production method according to the present invention can have the following characteristics.
(A) 0.2% proof stress in the rolling parallel direction is 900 to 1250 MPa
(B) The MBR / t value, which is the ratio of the minimum radius (MBR) at which cracks do not occur to the plate thickness (t) by performing a Badway W bending test, is 0.5 to 2.5.

In a preferred embodiment, the copper alloy obtained by the production method according to the present invention can have the following characteristics.
(A) 0.2% proof stress in the rolling parallel direction is 900 to 1050 MPa
(B) The MBR / t value, which is the ratio of the minimum radius (MBR) at which cracks do not occur to the plate thickness (t) after performing a Badway W bending test, is 0.5 to 2.0.

In yet another preferred embodiment, the copper alloy obtained by the production method according to the present invention can have the following characteristics.
(A) 0.2% yield strength in the rolling parallel direction is 1050 to 1250 MPa
(B) The MBR / t value, which is the ratio of the minimum radius (MBR) at which cracks do not occur to the plate thickness (t) by performing a Badway W bending test, is 1.5 to 2.5.

  The copper alloy obtained by the production method according to the present invention generally has a conductivity of 9-18% IACS, typically 10-15% IACS.

Uses of the copper alloy according to the present invention The copper alloy according to the present invention can be processed into copper products having various thicknesses and is useful as a material for various electronic components. The copper alloy according to the present invention is excellent as a small spring material requiring particularly high dimensional accuracy, and can be suitably used as a material for a switch, a connector, a jack, a terminal, a relay and the like, although not limited thereto. .

  Examples of the present invention will be described below together with comparative examples, but these examples are provided for better understanding of the present invention and its advantages, and are not intended to limit the invention.

Example 1 (Effect of manufacturing process on titanium copper properties)
When manufacturing the copper alloy of the present invention example, Ti, which is an active metal, is added as the second component, so a vacuum melting furnace was used for melting. In addition, in order to prevent unexpected side effects due to mixing of impurity elements other than the elements defined in the present invention, raw materials having a relatively high purity were carefully selected and used.

  First, after adding Mn, Fe, Mg, Co, Ni, Cr, Mo, V, Nb, Zr, Si, B and P to Cu in the compositions shown in Table 1, Ti having the composition shown in the same table was added. Each was added. After sufficient consideration was given to the retention time after the addition so that there was no undissolved residue of the added elements, these were injected into the mold in an Ar atmosphere to produce about 2 kg of ingots.

  After the homogenization annealing which heats at 950 degreeC with respect to the said ingot for 3 hours, it hot-rolled at 900-950 degreeC, and obtained the hot-rolled sheet of 10 mm in thickness. After descaling by chamfering, cold rolling was performed to obtain a strip thickness (1.5 mm), and a primary solution treatment was performed on the strip. The conditions for the first solution treatment were heating at 850 ° C. for 7.5 minutes. Next, after cold rolling to an intermediate plate thickness (0.10 mm), it was inserted into an annealing furnace capable of rapid heating and subjected to a final solution treatment. The heating conditions at this time were about 820 ° C. for 1 minute. Next, heat treatment was performed under the conditions described in Table 2. After descaling by pickling, it was cold-rolled to a plate thickness of 0.075 mm, and aged in an inert gas atmosphere to obtain test pieces of invention examples and comparative examples. The conditions for heat treatment and aging treatment are shown in Table 2.

About each obtained test piece, characteristic evaluation was performed on the following conditions. The results are shown in Table 2.
<Strength>
A JIS No. 13B specimen was prepared using a press so that the tensile direction was parallel to the rolling direction. The specimen was subjected to a tensile test according to JIS-Z2241, and the 0.2% proof stress (YS) in the rolling parallel direction was measured.
<Bending workability>
In accordance with JIS H 3130, a W-bending test of Badway (the bending axis is the same direction as the rolling direction) was performed to measure the MBR / t value, which is the ratio of the minimum radius (MBR) to the thickness (t) at which no cracks occur.
<Conductivity>
In accordance with JIS H 0505, the conductivity (% IACS) was measured by the 4-terminal method.
<Number density (X)>
About each obtained test piece, the number density (X) of the precipitate and the number ratio (Y) of grain boundary precipitation were calculated | required on condition of the following. The rolled surface was electropolished in a solution of 67% phosphoric acid + 10% sulfuric acid + water under conditions of 15 V 60 seconds to reveal the structure, washed with water and dried for observation. This was observed using a FE-SEM (electrolytic emission scanning electron microscope, Philips, XL30SFEG) at an acceleration voltage of 15 kV, a spot diameter of 4.0 μm, and a WD = 6.0 mm. The number density (X) of the two-phase particles) was counted. Specifically, a second containing a Ti-Cu-based precipitate (grain boundary reaction phase) having a complicated shape that precipitates along the crystal grain boundary as a grain boundary reaction type particle present in the observation field of 100 μm × 100 μm. The phase density was marked, and the number density was counted with one particle having a diameter of a maximum circle (see FIG. 1A) inscribed in the marked second phase particle of 0.5 μm or more as one particle.
<Number ratio (Y)>
Of the second phase particles having a particle size of 0.5 μm or more dispersed in the observation field counted in the above-described procedure, the particles existing at the grain boundaries with respect to the total number of second phase particles having a particle size of 0.5 μm or more in the observation field. The number ratio (Y) of precipitates having a diameter of 0.5 μm or more was measured. The crystal grain boundary was defined as an interface having a different contrast using a reflected electron image obtained by SEM observation. Regarding “number ratio of grain boundary precipitation of second phase particles having a particle size of 0.5 μm or more (Y)”, among the second phase particles having a particle size of 0.5 μm or more dispersed in the observation field, (A) the particle size For the second phase particles of 0.5 μm or more and less than 1.0 μm, (a) particles having a diameter of the smallest circle circumscribing the second phase particles (see FIG. 1A) of 0.5 μm or more and less than 1.0 μm: "1", (b) Particles having a diameter of the smallest circle circumscribing the second phase particles (see Fig. 1 (a)) of 1.0 µm or more: counted as "2", and (B) particle size of 1.0 µm For the second phase particles described above, when a mesh with an interval of 0.5 μm is applied to the observation field, “1 piece” is surrounded by 0.5 μm square, and protrudes outside the 0.5 μm square beyond the mesh. The part was counted as “1/2” (see FIG. 1B).

No. Reference numeral 1 is a conventional example. No. In No. 1, heat treatment (annealing) after solution treatment was not performed, and since the final aging temperature was low, the number density was small and the number ratio of grain boundary precipitation was small, so the strength was insufficient. On the other hand, no. In the case of 2, it turns out that intensity | strength improves.
No. 3 is a comparative example in which the aging treatment was performed at a low temperature without performing the heat treatment. No. In No. 3, annealing after solution treatment was not performed, and since the final aging temperature was low, the number density was small and the number ratio of grain boundary precipitation was small, so the strength was insufficient. On the other hand, no. In the case of No. 4, it can be seen that the strength is improved. No. 4 is compatible with both high strength and bending workability because aging treatment was performed at a low temperature. Although 5 is an example of the invention, it is an example in which the temperature of the aging treatment is lowered. No. 6 is an invention example in which the heating temperature during the heat treatment is set as high as possible. No. 7 is an invention example in which the heating temperature during heat treatment is made as low as possible.
No. No. 8 is a comparative example in which the heating temperature of the heat treatment was too high. 9 is a comparative example in which the heating temperature of the heat treatment was too low. No. Since No. 8 was over-annealed, the number density was high and the strength was insufficient. No. Since No. 9 was insufficiently annealed, the number density and the rate of precipitation at the grain boundaries decreased. Moreover, since the amount of precipitation was generally small, the strength was insufficient.
No. Reference numeral 10 is an invention example in which the degree of increase in conductivity by heat treatment is increased. No. 11 and no. 12 is a comparative example in which the degree of increase in electrical conductivity due to heat treatment was too large. In No. 11, since the conductivity increased too much by annealing after solution treatment, the second phase particles increased, and the second phase particles further increased after the subsequent rolling and aging steps, so the number density was It became high. No. In 11, the strength increased but the bending workability deteriorated. No. 12 is No. Since the number density increased further than 11, the rate of grain boundary precipitation also increased, the strength decreased from No. 11, and the bending workability further deteriorated.
No. 13 is a conventional example. Since annealing after solution treatment was not performed and the final aging temperature was low, the number density was small and the number ratio of grain boundary precipitation was small, so the strength was insufficient.
No. 14 and 16 show the effects of the present invention when a third element is added.
No. 15 and 17 are conventional examples. In No. 15, annealing after solution treatment was not performed, and since the final aging temperature was low, the number density was small and the number ratio of grain boundary precipitation was small, so the strength was insufficient. No. In No. 17, since annealing after solution treatment was not performed, the number density was small and the ratio of grain boundary precipitation was small, so that the strength was insufficient.
No. 18-20 shows the example which annealed after solution treatment for a long time. In Comparative Examples 18 to 20, since the annealing time after solution treatment was long, the number density increased, the strength decreased, and the bending workability deteriorated.

Example 2 (Effect of composition on titanium copper properties)
Other than changing the composition of titanium copper as shown in Table 3, A test piece was produced under the same production conditions as the test piece 4. Table 4 shows the results of the characteristic evaluation of the obtained test pieces.

  No. No. 21 is a comparative example in which the titanium concentration was too low. 24 is an example in which the titanium concentration was too high. NO. In No. 21, since the titanium concentration was low, the number of second-phase particles was small, the number ratio precipitated at the grain boundaries was low, and the strength was insufficient. No. Since No. 24 had a high titanium concentration, grain boundary precipitation occurred preferentially, the number ratio increased, and bending workability deteriorated.

Claims (5)

It contains 2.0 to 4.0% by mass of Ti, and at least one of Mn, Fe, Mg, Co, Ni, Cr, V, Nb, Mo, Zr, Si, B, and P as the third element. A copper alloy containing 0 to 0.5% by mass in total, consisting of the remaining copper and inevitable impurities,
In the structure observation by the electron microscope of the surface after electrolytic polishing of the rolled surface, the number density (X) of the second phase particles having a particle size of 0.5 μm or more is 0.04 to 0.11 particles / μm ² ,
A copper alloy, wherein the number ratio (Y) in which second phase particles having a particle size of 0.5 μm or more precipitate along the grain boundaries is 45 to 80%. The copper alloy is
At 550 to 1000 ° C., a solution treatment is performed in which the solid solubility limit of Ti is the same as the addition amount and heated to 0 to 20 ° C. higher than the solid solubility limit temperature and rapidly cooled.
Following the solution treatment, when the titanium concentration (% by mass) is [Ti], the conductivity increase value C (% IACS) is expressed by the following relational expression:
0.5 ≦ C ≦ (−0.50 [Ti] ² −0.50 [Ti] +14)
Heat treatment to increase the conductivity so as to satisfy,
Following the heat treatment, the final cold rolling is performed,
The copper alloy according to claim 1, which is produced by performing an aging treatment subsequent to final cold rolling.   A copper product using the copper alloy according to claim 1.   The electronic component produced using the copper alloy of Claim 1 or 2.   The connector produced using the copper alloy of Claim 1 or 2.

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