KR20200145798A - Titanium copper foil and method of manufacturing the same - Google Patents

Abstract

Provided are a titanium copper foil which is not easily deformed when used as a spring even if the thickness of the foil is 0.1 mm or less and can be suitably used as a conductive spring material for electronic parts such as autofocus camera modules, and a method for manufacturing the same. The titanium copper foil of the present invention contains 1.5 to 5.0 mass% of Ti and the remainder composed of copper and unavoidable impurities, has a thickness of 0.1 mm or less, and has a foil thickness change of 0.0 to 1.0 μm at five measuring points positioned side by side at intervals of 60 mm in a direction parallel to a rolling direction.

Description

Titanium copper foil and its manufacturing method {TITANIUM COPPER FOIL AND METHOD OF MANUFACTURING THE SAME}

The present invention relates to a Cu-Ti-based alloy foil having excellent strength, suitable for use as a conductive spring material such as an auto focus camera module.

An electronic component called an auto focus camera module is used in the camera lens part of a mobile phone. The auto focus function of the mobile phone camera operates the lens in a certain direction by the spring force of the material used in the auto focus camera module, and the spring force of the material is applied to the lens by the electromagnetic force generated by passing current through the coil wound around it. Operate in the opposite direction to the direction in which it works. The camera lens is driven by such a mechanism, and an autofocus function is exhibited (for example, Patent Documents 1 and 2).

Therefore, the copper alloy foil used in the auto focus camera module needs a spring strength sufficient to withstand material deformation due to electromagnetic force. If the spring strength is low, the material cannot withstand the displacement caused by the electromagnetic force, and permanent deformation (deformation) occurs, and after removing the electromagnetic force, it does not return to the initial position. When deformation occurs, when a constant current is passed, the lens cannot move to a desired position, and the autofocus function is not exhibited.

As the autofocus camera module, a Cu-Ni-Sn-based copper alloy foil having a foil thickness of 0.1 mm or less and a tensile strength of 1100 MPa or more or 0.2% proof strength has been used. However, in accordance with the recent demand for cost reduction, titanium copper foil, which is relatively cheaper than a Cu-Ni-Sn-based copper alloy, has been used, and the 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 in that deformation occurs, and therefore, the high strength is expected. As a technique for improving the titanium copper strength, there are those described in Patent Documents 3-6. In Patent Document 3, a method of adjusting the average grain diameter by final recrystallization annealing, and then performing cold rolling and aging treatment sequentially is described. In Patent Document 4, a method of sequentially performing cold rolling, aging treatment, and cold rolling after a solid solution treatment is described. In Patent Literature 5, after hot rolling and cold rolling are performed, solution treatment is performed in a temperature range of 750 to 1000°C for 5 seconds to 5 minutes, followed by cold rolling at a rolling rate of 0 to 50%, 300 to A method of adjusting the X-ray diffraction intensity of {420} on the plate surface is described by sequentially performing aging treatment at 550°C and finished cold rolling at a rolling rate of 0 to 30%. In Patent Document 6, by sequentially performing the first solution treatment, intermediate rolling, final solution treatment, annealing, final cold rolling, and aging treatment under predetermined conditions, the X-ray diffraction intensity of {220} on the rolling surface is obtained. A method of adjusting the half-value width has been proposed.

In addition, in order to increase the strength and suppress the occurrence of deformation, it is proposed to reduce the surface roughness in Patent Document 7, to adjust the crystal orientation in Patent Document 8, and to decrease the elongation modulus in Patent Document 9, respectively. have.

Japanese Unexamined Patent Application Publication No. 2004-280031 Japanese Unexamined Patent Application Publication No. 2009-115895 Japanese Patent Publication No. 4001491 Japanese Patent Publication No. 4259828 Japanese Unexamined Patent Application Publication No. 2010-126777 Japanese Unexamined Patent Application Publication No. 2011-208243 Japanese Patent Publication No. 5723849 Japanese Patent Publication No. 5526212 Japanese Unexamined Patent Application Publication No. 2014-074193

Among the Examples and Comparative Examples described in the specification of Patent Documents 3 to 6, some titanium copper having a 0.2% proof strength of 1100 MPa or more are also seen. However, in the prior art proposed in these Patent Documents 3 to 6, since deformation occurs when the load is removed by applying a load to the material and then removing the load, it cannot be used as a conductive spring material such as an autofocus camera module simply by having a high strength. I knew it.

In addition, Patent Documents 7 to 9 each propose a method of suppressing the occurrence of deformation, focusing on the deformation problem. However, it was found that the effect of the thin film with a thickness of 0.1 mm or less was not exhibited as expected with the techniques proposed in Patent Documents 7 to 9. In other words, the technology proposed in Patent Documents 7 to 9 exhibits a great effect when the foil thickness exceeds 0.1 mm, but when the foil thickness exceeds 0.1 mm, it is sufficiently effective that the foil thickness is predicted to exceed 0.1 mm. Found that it was not exerted.

The present invention aims to solve such a problem, and even if the thickness is thinner of 0.1 mm or less, deformation when used as a spring is small, and as a conductive spring material used for electronic device parts such as autofocus camera modules. An object of the present invention is to provide a titanium copper foil that can be used suitably and a method for producing the same.

Even if the inventor uses a means for suppressing deformation as in the prior art, the presence or absence of deformation in the thin titanium copper foil is affected by the thickness of the foil itself, so the effect exerted by such means is compared to that of the thicker thickness. I found it getting smaller. And even if it is a thin-thick titanium copper foil, by making the fluctuation|variation of the foil thickness small, it has found that the occurrence of deformation stays to a minimum when used as a spring.

Moreover, the titanium copper foil with such a small thickness fluctuation is similar to the conventional one, and when hot rolling, first cold rolling, solution treatment and second cold rolling are sequentially performed, the crystal grains are coarsened by solution treatment. , The solution treatment followed by the solution treatment followed by heat treatment and appropriate hardening, and then second cold rolling was obtained.

Based on these insights, the titanium copper foil of the present invention contains 1.5 to 5.0 mass% of Ti, the remainder is composed of copper and inevitable impurities, the thickness of the foil is 0.1 mm or less, and an interval of 60 mm in a direction parallel to the rolling direction. The fluctuations in the thickness of the foil at five measuring points located side by side are 0.0㎛ to 1.0㎛.

Further, it is preferable that the titanium copper foil has a tensile strength of 1100 MPa or more in a direction parallel to the rolling direction.

In addition, the titanium copper foil should further contain 0 to 1.0 mass% in total amount of at least one element selected from Al, Ag, B, Co, Fe, Mg, Mn, Mo, Ni, P, Si, Cr, and Zr. I can.

In addition, the method for producing a titanium copper foil of the present invention contains 1.5 to 5.0% by mass of Ti, and casts an ingot composed of copper and inevitable impurities with the remainder, and hot-rolled and first cold-rolled with respect to the ingot Solution treatment to adjust the diameter to 100 to 160 µm, heat treatment after solution treatment to adjust the increase in tensile strength to 100 to 240 MPa for tensile strength after solution treatment, second cold rolling, and 200 to 450°C temperature It includes performing the aging treatment in this order when heating at 2 to 20 hours.

In addition, in this manufacturing method, it is preferable to set the reduction ratio in the 2nd cold rolling to 55% or more.

Further, this manufacturing method may further include a third cold rolling having a reduction ratio of 35% or more after the aging treatment.

According to the present invention, by making the fluctuation of the foil thickness at five measuring points parallel to the rolling direction at intervals of 60 mm to be 0.0 µm to 1.0 µm, even a thin one having a thickness of 0.1 mm or less could be used as a spring. It is possible to provide a titanium copper foil having a small deformation at the time. Such titanium copper foil can be suitably used as a conductive spring material used for electronic device parts such as autofocus camera modules.

1 is a schematic diagram showing a method of measuring the amount of deformation of the embodiment.

Hereinafter, an embodiment of the present invention will be described in detail.

The titanium copper foil of one embodiment of the present invention contains 1.5 to 5.0 mass% of Ti, and the remainder is composed of copper and unavoidable impurities, at 5 measuring points located side by side at intervals of 60 mm in a direction parallel to the rolling direction. The foil thickness fluctuation is 0.0 µm to 1.0 µm.

(Ti concentration)

In the titanium copper foil according to the present invention, the Ti concentration is 1.5 to 5.0% by mass. Titanium copper increases strength and conductivity by dissolving Ti in the Cu matrix by solution treatment, and dispersing fine precipitates in the alloy by aging treatment.

When the Ti concentration is less than 1.5% by mass, precipitation of the precipitate becomes insufficient, and the desired strength cannot be obtained. When the Ti concentration exceeds 5.0% by mass, workability deteriorates, and the material is liable to crack during rolling. Considering the balance of strength and workability, the preferred Ti concentration is 2.9 to 3.5% by mass.

(Other additive elements)

In the titanium copper foil according to the present invention, by containing at least one of Al, Ag, B, Co, Fe, Mg, Mn, Mo, Ni, P, Si, Cr, and Zr in a total amount of 0 to 1.0 mass%, Strength can be further improved. The total content of these elements is 0, that is, these elements need not be included. The upper limit of the total content of these elements is set to 1.0% by mass, because if it exceeds 1.0% by mass, workability deteriorates and the material is liable to crack during hot rolling.

(The tensile strength)

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

(Foil thickness fluctuation)

In the titanium copper foil of the present invention, when five continuous measuring points are set at intervals of 60 mm in a direction parallel to the rolling direction, and the foil thickness of the five measuring points is measured, the fluctuation of the foil thickness is 0.0 μm to 1.0. Μm.

Here, the foil thickness fluctuation is defined as the difference between the maximum value and the minimum value of the five foil thickness data obtained by measuring the foil thickness at five measuring points arranged at intervals of 60 mm apart in the rolling direction. By making the fluctuation of the foil thickness small, it becomes possible to improve the deformability. It is included in the present invention if the foil thickness measurement at these five measurement points is carried out at least once, and the foil thickness variation of the five measurement points in at least one measurement among them is within the range of 0.0 µm to 1.0 µm.

(Copper foil thickness)

In one embodiment of the titanium copper foil of the present invention, the foil thickness is 0.1 mm or less, 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.

(Manufacturing method)

In order to manufacture the titanium copper foil as described above, first, a raw material such as electric copper and Ti is dissolved in a melting furnace to obtain a molten metal having a desired composition. Then, this molten metal is cast with an ingot. In order to prevent oxidative abrasion of titanium, it is preferable to perform melting and casting under vacuum or in an inert gas atmosphere. Thereafter, the ingot is typically subjected to hot rolling, first cold rolling, solution treatment, heat treatment after solution treatment, second cold rolling, aging treatment, third cold rolling, and rust prevention treatment in this order. It is completed with a foil having a foil thickness and characteristics.

The hot-rolling and subsequent first cold-rolling conditions are sufficient to be carried out under the customary conditions used in the production of titanium copper, and there are no special requirements for this. Further, the solution treatment may be performed under conventional conditions, for example, 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 range is preferably 800°C to 950°C, and the preferred time range is 120 seconds (2 minutes) to 300 seconds (5 minutes). However, as long as it is a temperature and time at which the average crystal grain diameter can be adjusted, it may be outside such a preferable range.

The average grain diameter adjusted in the solution treatment is 100 to 160 µm. When this average grain diameter is less than 100 µm, the fluctuation in the thickness of the foil exceeds 1.0 µm in subsequent cold rolling. When the average grain diameter exceeds 160 µm, the fluctuation in the thickness of the thin film in subsequent cold rolling becomes small, but a thick oxide film and an internal oxide layer are formed on the surface, making it difficult to remove. In addition, the effect of reducing the fluctuation in the thickness of the foil is saturated when the average grain diameter adjusted in the solution treatment exceeds 160 µm.

The average crystal grain diameter is determined by polishing the plate surface (rolled surface), etching, observing the surface with an optical microscope, and measuring 100 crystal grains by the cutting method of JIS 　 H0501.

In the post-solution heat treatment performed following the solution treatment, the increase in tensile strength is adjusted. The heat treatment after solution treatment is to heat the titanium copper alloy subjected to the solution treatment to age harden. The heat treatment after solution treatment is performed at a temperature lower than the solution treatment temperature for the purpose of age-hardening. The heat treatment after solution treatment has a preferred temperature range of 600 to 700°C, and a preferred time range of 120 seconds to 300 seconds (5 minutes). However, as long as it is a temperature and time at which the increase amount of the tensile strength can be adjusted, it may be outside the preferred range.

The increase in tensile strength adjusted in heat treatment after solutionization is 100-240 MPa. When the tensile strength increase amount is less than 100 MPa, the fluctuation in the thickness of the foil exceeds 1.0 µm in the subsequent cold rolling. When the increase in tensile strength exceeds 240 MPa, the fluctuation in the thickness of the foil in subsequent cold rolling becomes small, but the continuation of cold rolling itself becomes difficult due to work hardening. In addition, the effect of reducing the fluctuation of the foil thickness is saturated when the increase in the tensile strength adjusted by the heat treatment performed after the solution treatment exceeds 240 MPa.

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

Increased amount of tensile strength = Tensile strength after solution treatment and heat treatment-Tensile strength after solution treatment (after solution treatment and before heat treatment)

In order to obtain the above-described strength, the reduction ratio of the second cold rolling is preferably set to 55% or more. More preferably, it is 60% or more, and even more preferably 65% or more. When this reduction ratio is less than 55%, it becomes difficult to obtain a tensile strength of 1100 MPa or more. Although the upper limit of the reduction ratio is not particularly defined in terms of strength for the purpose of the present invention, it does not exceed 99.8% industrially.

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

It is preferable to set the reduction ratio of the 3rd cold rolling to 35% or more. It is more preferably 40% or more, and even more preferably 45% or more. When this reduction ratio is less than 35%, it becomes difficult to obtain a tensile strength of 1100 MPa or more. The upper limit of the reduction ratio is not particularly defined in terms of the target strength, but it does not exceed 99.8% industrially. In addition, the third cold rolling may be omitted in cases where the high strength is not required.

In addition, generally, after the heat treatment, the surface is pickled or polished to remove the oxide film or oxide layer generated on the surface. In the present invention, it is also possible to perform pickling or polishing of the surface after heat treatment.

(Usage)

The titanium copper foil of the present invention is not limited, but can be suitably used as a material for parts for electronic devices such as switches, connectors, jacks, terminals, relays, etc., and in particular, a conductive spring material used for electronic device parts such as autofocus camera modules. It can be used suitably.

Example

Next, the titanium copper foil of the present invention was actually produced by trial and the performance thereof was evaluated, and thus the following description will be given. However, the description herein is for the purpose of mere illustration and is not intended to be limited thereto.

The properties of this material were investigated using an alloy containing Ti in a predetermined concentration and the balance consisting of copper and unavoidable impurities as an experimental material.

<Production conditions>

Preparation of the prototype was carried out as follows. First, electric copper was dissolved in a vacuum melting furnace, and an ingot having a thickness of 30 mm was prepared at a predetermined Ti concentration.

This ingot was heated at 950° C. for 3 hours and hot-rolled to a thickness of 10 mm. The oxidized scale produced by hot rolling was removed with a grinder to perform grinding. In addition, the thickness after this grinding was 9 mm. Next, 1st cold rolling was performed, and it rolled to a thickness of 1.5 mm. In the subsequent solution treatment, a sample was placed in an electric furnace heated to 800 to 950°C, and after holding for 120 seconds to 300 seconds (5 minutes), the sample was placed in a water bath and rapidly cooled. Following the solution treatment, heat treatment was performed after the solution treatment. In the heat treatment after the solution treatment, a sample was placed in an electric furnace heated to 600 to 700°C, and after holding for 120 seconds to 300 seconds (5 minutes), the sample was placed in a water bath and rapidly cooled. And the 2nd cold rolling was performed, and rolling was carried out to a thin thickness of 0.03 mm by 98% of rolling reduction here. After that, it was heated at 300°C for 10 hours as an aging treatment. Here, this temperature of the aging treatment was selected so that the tensile strength after aging was maximized. In addition, 3rd cold rolling was not performed.

Each of the following evaluations was performed on the samples prepared as described above.

<Foil thickness fluctuation>

The foil thickness was measured for five points continuous in the rolling direction at intervals of 60 mm, and the difference between the maximum and minimum values of the five data was calculated, and the value was taken as the thickness variation. As a device for measuring the thickness of the foil, a manufacturer of Nikon Co., Ltd., a product name of DIGIMICRO, and a type of Nikon MH-15M were used. The thickness of the foil was measured in sub-micron order (0.1 μm unit).

<transformation>

A short rectangular sample with a width of 10 mm was taken so that the longitudinal direction became the rolling parallel direction. Short rectangular samples were taken at 5 locations continuously in the rolling direction at intervals of 60 mm, and were made into 5 short rectangular samples. Then, as shown in Fig. 1, one end of the sample is fixed, and the punch processed with the tip of the knife edge at the position of the distance L from the fixed end is pressed at a moving speed of 1 mm/min, and the distance ( After giving the bend of d), the punch was unloaded by turning it to the initial position. After unloading, the amount of deformation (δ) was determined. This measurement was performed on each of five short rectangular samples to obtain five amounts of deformation (δ). The deformation amount (δ) with the highest value among the five deformation amounts (δ) was taken as the measurement value.

The test conditions were L=3mm and d=2mm when the foil thickness of a sample was 0.05 mm or less, and L=5mm and d=4mm when the foil thickness was thicker than 0.05mm. In addition, the amount of deformation was measured with a resolution of 0.01 mm, and when no deformation was detected, it was expressed as <0.01 mm.

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

[Table 1]

[Table 2]

Inventive Examples 1 to 25 within the scope of the present invention have a 0.2% proof strength of 1100 MPa or more, a foil thickness variation of 0.0 µm to 1.0 µm, a small value, a deformation amount of less than 0.01 mm, and all of them exhibited good characteristics.

On the other hand, in Comparative Examples 1 to 3, since the solution treatment was outside the preferred range, the average crystal grain diameter was less than 100 µm, and the amount of deformation was 0.02 mm or more due to the increase in the thickness fluctuation.

In Comparative Examples 4 to 6, since the heat treatment after solution treatment was out of the preferred range, the increase in tensile strength before and after heat treatment after solution treatment was less than 100 MPa, and the thickness fluctuation became a high value exceeding 1.0 µm. A high value of 0.02 mm or more was shown.

Since Comparative Example 7 was not subjected to heat treatment after solution treatment, the increase in tensile strength before and after heat treatment after solution treatment became zero, and the thickness fluctuation became a high value exceeding 1.0 µm, and the amount of deformation was as high as 0.06 mm. Indicated the value.

In Comparative Example 8, since the solution treatment was out of the preferred range and the heat treatment was not performed after the solution treatment, the fluctuation of the foil thickness became a high value exceeding 1.0 µm, and the amount of deformation was as high as 0.08 mm.

Comparative Example 9 had a low tensile strength because the Ti component was outside the lower limit.

In Comparative Examples 10 and 11, since the Ti component or subcomponent exceeded the upper limit, cracking occurred in hot rolling, and processing was not possible.

Claims (4)

It contains 1.5 to 5.0% by mass of Ti, the remainder is composed of copper and inevitable impurities, the thickness of the foil is 0.1 mm or less, and the fluctuations in the thickness of the foil at five measuring points located parallel to the rolling direction at 60 mm intervals 0.0㎛ to 1.0㎛, titanium copper foil. The method of claim 1,
A titanium copper foil having a tensile strength of 1100 MPa or more in a direction parallel to the rolling direction. The method according to claim 1 or 2,
Al, Ag, B, Co, Fe, Mg, Mn, Mo, Ni, P, Si, Cr and Zr one or more elements selected from a total amount of 0 to 1.0 mass% further containing, titanium copper foil. For casting an ingot containing 1.5 to 5.0% by mass of Ti and the remainder of copper and unavoidable impurities, and then hot rolling, first cold rolling, and adjusting the average grain diameter to 100 to 160 μm for the ingot. After sieving treatment, heat treatment after solution treatment to adjust the amount of increase in tensile strength relative to tensile strength after solution treatment to 100 to 240 MPa, second cold rolling, and heating at 200 to 450°C over 2 to 20 hours A method for producing a titanium copper foil comprising performing an aging treatment in this order.

Images