TW201736609A - Titanium copper foil and its production method being suitable to be used as the titanium copper foil for the conductive spring material used in the equipment parts such as the automatic focusing photographer module - Google Patents

Abstract

The present invention provides a thin titanium copper foil to be able to be used as the spring of small relaxation even with thickness below 0.1 <mu>m, being suitable to be used as the titanium copper foil for the conductive spring material used in the electronic equipment parts such as the automatic focusing photographer module, and its production method. The titanium copper foil in the present invention has the copper thickness of below 0.1 mm and contains Ti content of 1.5~4.5 mass%, with the remainder constituted by copper and inevitable impurities, and the foil thickness variation in the five measuring points arranged at intervals of 60 mm compartments in the direction parallel to the rolling direction is 0.0<mu>m~1.0<mu>m.

Description

Titanium copper foil and manufacturing method thereof

The present invention relates to a Cu-Ti alloy foil which is suitable for use as an electrically conductive spring material for an autofocus camera module or the like and which has excellent strength.

In general, the camera lens portion of a mobile phone uses an electronic component called an autofocus camera module. The auto-focusing function of the mobile phone lens, on the one hand, moves the lens in a certain direction by the elastic force of the material used in the auto-focusing camera module, and on the other hand, by flowing a current in the coil wound around, The electromagnetic force generated causes the lens to move in a direction opposite to the direction in which the material acts. The camera head is driven by a mechanism similar to the above and functions as an auto focus function (e.g., Patent Documents 1, 2).

Therefore, the copper alloy foil used in the autofocus camera module needs to have the strength to withstand the deformation of the material due to electromagnetic force. If the strength is low, the material cannot withstand the displacement caused by the electromagnetic force, permanent deformation (relaxation) occurs, and the electromagnetic force cannot be returned to the initial position after the electromagnetic force is unloaded. Once slack occurs, when a certain current flows, the lens cannot move to the desired position and the auto focus function cannot be performed.

The autofocus camera module uses a Cu-Ni-Sn alloy foil having a foil thickness of 0.1 mm or less and a tensile strength of 1100 MPa or a 0.2% relief strength. However, with the cost-saving requirements in recent years, people are more willing to use titanium-copper foils with relatively cheaper materials than Cu-Ni-Sn-based copper alloy foils, and this demand is increasing.

On the other hand, the strength of the titanium copper foil is lower than that of the Cu-Ni-Sn-based copper alloy foil, and there is a problem of slack. Therefore, it is required to have high strength. As a technique for improving the strength of titanium copper, the contents described in Patent Documents 3 to 6 can be referred to. Patent Document 3 describes adjusting average crystallization in final recrystallization annealing The particle size is followed by a method of cold rolling and aging treatment. Patent Document 4 describes a method of sequentially performing cold rolling, aging treatment, and cold rolling after solution treatment. Patent Document 5 describes a method of performing a solution treatment after hot rolling and cold rolling, that is, holding in a temperature range of 750 to 1000 ° C for 5 seconds to 5 minutes, and then sequentially performing a rolling ratio of 0. ~50% cold rolling, aging treatment at 300~550 °C, and finishing cold rolling with 0:30% elongation, adjusting the X-ray diffraction intensity of {420} in the panel. Patent Document 6 proposes a method of adjusting the { in the rolling plane by sequentially performing the first solution treatment, the intermediate rolling, the final solution treatment, the annealing, the final cold rolling, and the aging treatment under predetermined conditions. The half-value width of the X-ray diffraction intensity of 220}.

Further, since not only the strength but also the occurrence of slack is suppressed, Patent Document 7 proposes to reduce the surface roughness, Patent Document 8 proposes to adjust the crystal orientation, and Patent Document 9 proposes to reduce the Young's modulus.

[Practical Technical Literature]

Patent Document 1: Japanese Patent Laid-Open Publication No. 2004-280031.

Patent Document 2: Japanese Patent Laid-Open Publication No. 2009-115895.

Patent Document 3: Japanese Invention Patent No. 4001491.

Patent Document 4: Japanese Patent No. 4259828.

Patent Document 5: Japanese Patent Laid-Open Publication No. 2010-126777.

Patent Document 6: Japanese Patent Laid-Open Publication No. 2011-208243.

Patent Document 7: Japanese Patent No. 5723849.

Patent Document 8: Japanese Invention Patent No. 5526212.

Patent Document 9: Japanese Patent Laid-Open Publication No. 2014-074193.

In the examples and comparative examples described in the specifications of Patent Documents 3 to 6, it is possible to see several titanium copper having a 0.2% fall strength of 1100 MPa or more. However, as is known from the prior art proposed in Patent Documents 3 to 6, it is known that the load is increased after the material is deformed, and the load is removed, which is slack, and cannot be used as a conductive spring material such as an autofocus camera module by high strength.

Further, in Patent Documents 7 to 9, each of the methods for focusing on the problem of relaxation and suppressing the occurrence of the slack is proposed. However, in the technical solutions of Patent Documents 7 to 9, the titanium-copper foil which is thin when the foil thickness is 0.1 mm or less cannot exhibit the effect as expected. In other words, although the technique of Patent Documents 7 to 9 can exhibit a large effect when the foil thickness exceeds 0.1 mm, a substance having a foil thickness of more than 0.1 mm cannot be predicted from a substance having a foil thickness exceeding 0.1 mm. The full effect of the degree.

The present invention has been made to solve the above problems, and an object thereof is to provide a titanium copper foil and a method for producing the same, which is suitable for use as an automatic focusing even when a thin substance having a foil thickness of 0.1 mm or less is used as a spring. A conductive spring material of an electronic device component such as a camera module is used.

The inventors have found that even if a method of controlling relaxation similar to the prior art is used, the presence or absence of slack in the thin copper foil having a small foil thickness is affected by the thickness of the foil itself, and thus, compared with a thick material, The effect of the means is even smaller. Therefore, the present inventors have deduced that a titanium copper foil having a small thickness can minimize the occurrence of slack when used as a spring by reducing the change in foil thickness.

Further, it has been found that such a titanium copper foil having a small foil thickness change has coarsened crystal grains by solid solution treatment in the same manner as before in the hot rolling, the first cold rolling, the solution treatment, and the second cold rolling. At the same time, after the solution treatment, the solid solution is dissolved, and the heat treatment is appropriately performed to be hardened, and then obtained after the second cold rolling.

Based on the above knowledge, the titanium copper foil of the present invention contains 1.5 to 5.0 mass of Ti, and the balance is composed of copper and unavoidable impurities, and the foil thickness is 0.1 mm or less, and is juxtaposed at intervals of 60 mm in a direction parallel to the rolling direction. The foil thickness of the five measurement points was changed from 0.0 μm to 1.0 μm.

Therefore, the titanium copper foil preferably has a tensile strength of 1100 MPa or more in a direction parallel to the rolling direction.

Further, the titanium copper foil further contains one or more selected from the group consisting of Al, Ag, B, Co, Fe, Mg, Mn, Mo, Ni, P, Si, Cr, and Zr in a total amount of 0 to 1.0% by mass. element.

Further, the method for producing a titanium copper foil according to the present invention includes the steps of: casting an ingot containing 1.5 to 5.0% by mass of Ti and having a balance of copper and unavoidable impurities; and sequentially performing hot rolling for the ingot. a cold rolling, the average crystal grain diameter is adjusted to 100~160μm solution treatment, phase The increase in the tensile strength of the tensile strength after the solution treatment is adjusted to a post-solid solution heat treatment of 100 to 240 MPa, a second cold rolling, and an aging treatment at a temperature of 200 to 450 ° C for 2 hours to 20 hours.

Further, in the production method, it is preferable to set the reduction ratio in the second cold rolling to 55% or more.

Moreover, this manufacturing method can also include the third cold rolling in which the reduction ratio is set to 35% or more after the aging treatment.

According to the present invention, there is provided a titanium copper foil which is set to have a thickness of 0.0 μm to 1.0 μm by a thickness of five measurement points which are arranged at intervals of 60 mm in a direction parallel to the rolling direction, even if the thickness is foil A thin substance of 0.1 mm or less has a small slack when used as a spring. Such a titanium copper foil is suitable for use as a conductive spring material used in electronic equipment components such as autofocus camera modules.

Fig. 1 is a schematic view showing a method of measuring the amount of slack in the embodiment.

Embodiments of the present invention will be described in detail below.

The titanium copper foil according to one embodiment of the present invention contains 1.5 to 5.0% by mass of Ti, and the balance is composed of copper and unavoidable impurities, and 5 measurement points which are juxtaposed at intervals of 60 mm in a direction parallel to the rolling direction The change in foil thickness is from 0.0 μm to 1.0 μm.

[Ti concentration]

In the titanium copper foil according to the present invention, the Ti concentration is set to be 1.5 to 5.0% by mass. Titanium copper is solid-dissolved into the Cu matrix by solution treatment, and fine precipitates are dispersed in the alloy by aging treatment, thereby increasing strength and electrical conductivity.

When the Ti concentration is less than 1.5% by mass, the precipitation of precipitates may be insufficient, and it may be difficult to obtain a desired strength. When the Ti concentration exceeds 5.0% by mass, the workability is deteriorated, and the material is easily broken during rolling. The concentration is preferably 2.9 to 3.5% by mass in consideration of the balance between strength and workability.

[other added elements]

The titanium copper foil according to the present invention contains at least one selected from the group consisting of Al, Ag, B, Co, Fe, Mg, Mn, Mo, Ni, P, Si, Cr, and Zr in a total amount of 0 to 1.0% by mass. The element can be used to further increase the strength. The total content of the above elements is 0, that is, the above elements may not be included. The upper limit of the total content of the above elements is set to 1.0% by mass because if it exceeds 1.0% by mass, the workability is deteriorated, and the material is easily broken during hot rolling.

[tensile strength]

The preferred titanium copper, which is a conductive spring material of the autofocus camera module, has a tensile strength of 1100 MPa or more, more preferably 1300 MPa or more. In the present invention, the tensile strength in the direction parallel to the rolling direction of the titanium copper foil was measured, and the tensile strength was measured in accordance with JIS Z2241 (Metal Material Tensile Test Method).

[Foil thickness change]

In the titanium copper foil of the present invention, five measurement points are continuously set at intervals of 60 mm in a direction parallel to the rolling direction, and when the foil thicknesses of the five measurement points are measured, the foil thickness is changed to 0.0μm~1.0μm.

Here, the foil thickness variation is defined as the maximum and minimum values of the five foil thickness data obtained by measuring the foil thickness by five measurement points spaced apart by 60 mm in the rolling direction and juxtaposed. Poor. By reducing the change in foil thickness, the resistance to slack can be improved. The foil thickness measurement at the five measurement points as described above is performed at least once, and the foil thickness variation of the five measurement points is within the range of 0.0 μm to 1.0 μm by the at least one measurement.

[Thickness of copper foil]

In one embodiment of the titanium copper foil of the present invention, the foil thickness is 0.1 mm or less, and in a typical embodiment, the foil thickness is 0.018 mm to 0.08 mm, and in a more typical embodiment, the foil thickness is 0.02 mm to 0.05 mm.

[Production method]

When the titanium copper foil as described above is produced, first, a raw material such as electrolytic copper or Ti is melted in a melting furnace to obtain a desired combined melt. The melt is then cast into an ingot. In order to prevent oxidative wear of titanium, it is preferred to carry out melting and casting in a vacuum or an inert gas atmosphere. Thereafter, for the ingot, typically, according to hot rolling, first cold rolling, solution treatment, post-solution heat treatment, second cold rolling, aging treatment, third cold rolling, anti-rust treatment, the desired foil is obtained. Thick and characteristic foil.

The hot rolling and the subsequent first cold rolling are carried out under the usual conditions in the production of titanium copper, and there is no particular requirement here. Further, the solution treatment may be carried out under customary conditions, and for example, it can be carried out at 700 to 1000 ° C for 5 seconds to 30 minutes.

In the solution treatment, in order to adjust the average crystal grain diameter, the temperature is preferably in the range of 800 ° C to 950 ° C, and the preferred time range is from 120 seconds (2 minutes) to 300 seconds (5 minutes). However, as the temperature and time at which the average crystal grain diameter can be adjusted, it is preferable to be out of the above range.

The average grain size adjusted in the solution treatment is 100 to 160 μm. If the average crystal grain diameter is less than 100 μm, the foil thickness changes in the subsequent cold rolling exceeds 1.0 μm. When the average crystal grain diameter exceeds 160 μm, although the foil thickness variation in the subsequent cold rolling is reduced, a thick oxide film and an internal oxide layer are formed on the surface, which is difficult to remove. Further, the effect of reducing the change in the thickness of the foil is to be saturated when the average crystal grain diameter adjusted in the solution treatment exceeds 160 μm.

With respect to the average crystal grain diameter, the plate surface (rolled surface) was polished and then etched, and the above surface was observed by an optical microscope, and 100 crystal grains were measured by a cutting method of JIS H0501 standard.

The increase in tensile strength is adjusted in the post-solution heat treatment immediately after the solution treatment. The heat treatment after solution treatment heats and ages the titanium-copper alloy subjected to the solution treatment. From the viewpoint of age hardening, the heat treatment after solution treatment is carried out at a temperature lower than the solution treatment temperature. The temperature after the solution treatment is preferably in the range of 600 to 700 ° C, or preferably in the range of 120 to 300 seconds (5 minutes). However, if it is a temperature and time capable of adjusting the increment of the tensile strength, it may preferably be a range outside the range.

The increase in tensile strength adjusted by the post-solution heat treatment is 100 to 240 MPa. When the increase in tensile strength is less than 100 MPa, the thickness of the foil in the subsequent cold rolling varies by more than 1.0 μm. When the increase in the tensile strength exceeds 240 MPa, the change in the thickness of the foil in the subsequent cold rolling becomes small, but the work of the cold rolling itself is difficult due to the work hardening. Further, the effect of reducing the change in the thickness of the foil is such that the increase in the tensile strength adjusted by the heat treatment after the solution treatment is more than 240 MPa.

The increase in the tensile strength is an increase in the tensile strength before and after the heat treatment after solution treatment, and can be calculated by the following formula.

Increment of tensile strength = tensile strength after heat treatment after solution treatment - tensile strength after solution treatment (before heat treatment after solution treatment)

In order to obtain the above strength, the reduction ratio of the second cold rolling is preferably set to 55% or more, more preferably 60% or more, still more preferably 65% or more. When the reduction ratio is less than 55%, it is difficult to obtain a tensile strength of 1100 MPa or more. From the viewpoint of the strength as the object of the present invention, the upper limit of the reduction ratio is not particularly specified, but it is industrially not more than 99.8%.

The heating temperature for the aging treatment is set to 200 to 450 ° C or higher, and the heating time is set to 2 hours to 20 hours. When the heating temperature is less than 200 ° C or exceeds 450 ° C, it is difficult to obtain a tensile strength of 1100 MPa or more. When the heating time is less than 2 hours or exceeds 20 hours, it is difficult to obtain a tensile strength of 1100 NPa or more.

The reduction ratio of the third cold rolling is preferably set to 35% or more. More preferably, it is set to 40% or more, and more preferably set to 45% or more. When the reduction ratio is less than 35%, it is difficult to obtain a tensile strength of 1100 MPa or more. The upper limit of the reduction ratio is not particularly specified in terms of the strength of the purpose, but it is not more than 99.8% in the industry. In addition, the third cold rolling can be omitted when such high strength use is not pursued.

Further, after the heat treatment, the oxide film or the oxide layer generated on the surface is removed, and the surface is pickled or polished. In the present invention, surface pickling or polishing can also be performed after the heat treatment.

[use]

The titanium copper foil of the present invention is not limited, but is suitable for use as a material of electronic equipment components such as switches, connectors, sockets, terminals, relays, and the like, and is particularly suitable as a conductive spring used in electronic equipment components such as autofocus camera modules. Materials to use.

[Examples]

Next, the titanium copper foil of the present invention is actually produced and evaluated for its performance, which will be described below. However, the description herein is for illustrative purposes only and is not intended to be limiting.

An alloy containing a predetermined concentration of Ti and a balance of copper and unavoidable impurities was used as an experimental material, and the characteristics of the material were investigated.

[Manufacture conditions]

The manufacture of the test article was carried out as follows. First, electrolytic copper was melted in a vacuum melting furnace, and an ingot having a thickness of 30 mm was produced at a predetermined Ti concentration.

The ingot was heated at 950 ° C for 3 hours, and hot rolled to be rolled to a thickness of 10 mm. The scale formed during hot rolling is removed by a grinder and ground. In addition, the thickness after the polishing was 9 mm. Thereafter, the first cold rolling was performed and rolled to a thickness of 1.5 mm. In the subsequent solution treatment, the sample was placed in an electric furnace heated to 800 to 950 ° C and held for 120 seconds to 300 seconds (5 minutes), and then the sample was placed in the water tank and rapidly cooled. After the solution treatment, the solution treatment is carried out, followed by heat treatment. In the heat treatment after the solution treatment, the sample was placed in an electric furnace heated to 600 to 700 ° C and held for 120 seconds to 300 seconds (5 minutes), and then the sample was placed in the water tank to be rapidly cooled. Then, a second cold rolling was performed, where the foil thickness was rolled to 0.03 mm at a reduction ratio of 98%. Thereafter, as an aging treatment, it was heated at 300 ° C for 10 hours. Here, the temperature of the aging treatment may be selected from the tensile strength after aging. In addition, the third cold rolling was not performed.

For the samples prepared as above, the following were evaluated separately.

[Foil thickness change]

The foil thickness measurement was performed at five points continuous in the rolling direction at intervals of 60 mm, and the difference between the maximum value and the minimum value of the five data was calculated and the value was changed as the foil thickness. As a device for measuring the thickness of the foil, the manufacturer is Nikon Co., Ltd., the product name is DIGIMICRO, and the model is Nikon MH-15M. The foil thickness was measured in micronanometers (0.1 μm units).

[relaxation]

A rectangular sample with a width of 10 mm is selected so that the long side direction is parallel to the rolling direction. The rectangular sample was selected from five locations that were continuous at 60 mm intervals in the rolling direction and served as five rectangular samples. Then, as shown in Fig. 1, one end of the fixed sample is pressed at a position of the fixed end L at a moving speed of 1 mm/min to press the tip into a cutting edge, and after the offset of the sample distance d is given Return the punch to its original position and unload it. After the unloading, the amount of slack δ is obtained. The above measurement was performed on five rectangular samples, respectively, and five relaxation amounts δ were obtained. The highest slack amount δ among the five slack amounts δ was taken as a measured value.

The test conditions were: when the foil thickness of the sample was 0.05 mm or less, L = 3 mm and d = 2 mm; when the foil thickness was thicker than 0.05 mm, L = 5 mm and d = 4 mm. Further, the amount of slack was measured by a resolution of 0.01 mm, and when the amount of slack was not detected, it was recorded as <0.01 mm.

The above evaluation results are shown in Table 1 together with predetermined manufacturing conditions.

Inventive Examples 1 to 25 within the scope of the present invention have a 0.2% drop strength of 1100 MPa or more, a foil thickness change of 0.0 μm to 1.0 μm, and a slack amount of less than 0.01 mm, and all exhibit good characteristics.

On the other hand, in Comparative Examples 1 to 3, since the preferable range of the solution treatment was deviated, the average crystal grain diameter was less than 100 μm because the change in the thickness of the foil was increased, and the amount of slack was shown to be a high value of 0.02 mm or more.

In Comparative Examples 4 to 6, the preferred range of the solution treatment was removed, and the increase in tensile strength before and after the heat treatment after solution treatment was less than 100 MPa, and the thickness of the foil was changed to a high value exceeding 1.0 μm, and the amount of relaxation was 0.02 mm or more. High value.

In Comparative Example 7, since the heat treatment after the solution treatment was not performed, the increase in the tensile strength before and after the heat treatment after the solution treatment was zero, and the thickness of the foil was changed to a high value exceeding 1.0 μm, indicating that the amount of slack was 0.06 mm. Value.

In Comparative Example 8, since the range of the solution treatment was removed and the heat treatment after the solution treatment was not performed, the foil thickness was changed to a high value exceeding 1.0 μm, and the amount of slack was shown to be a high value of 0.08 mm.

In Comparative Example 9, the tensile strength was lowered due to the lower limit of the Ti component.

In Comparative Examples 10 and 11, since the Ti component or the secondary component was out of the upper limit, it was damaged during hot rolling, and processing was impossible.

Claims (4)

A titanium copper foil comprising 1.5 to 5.0% by mass of Ti, the balance being composed of copper and unavoidable impurities, a foil thickness of 0.1 mm or less, and juxtaposed at intervals of 60 mm in a direction parallel to the rolling direction. The foil thickness variation of the five measurement points was 0.0 μm to 1.0 μm. The titanium copper foil according to claim 1, wherein the tensile strength in a direction parallel to the rolling direction is 1100 MPa or more. The titanium copper foil according to claim 1 or 2, further comprising a total amount of 0 to 1.0% by mass selected from the group consisting of Al, Ag, B, Co, Fe, Mg, Mn, Mo, Ni, One or more elements of P, Si, Cr, and Zr. A method for producing a titanium copper foil, comprising: casting an ingot containing 1.5 to 5.0% by mass of Ti and having a balance of copper and unavoidable impurities; and sequentially performing hot rolling on the ingot First cold rolling, a solution treatment in which the average crystal grain diameter is adjusted to 100 to 160 μm, and a tensile strength increase in the tensile strength relative to the tensile strength after solution treatment is adjusted to a heat treatment after solid solution of 100 to 240 MPa, The second cold rolling and the aging treatment are carried out at a temperature of 200 to 450 ° C for 2 hours to 20 hours.