TWI649435B - Titanium copper foil, expanded copper products, electronic equipment parts, and autofocus camera modules - Google Patents

Abstract

The present invention provides a thin titanium copper foil with a foil thickness of 0.1 μm or less, which has excellent solder wettability and solder bonding strength, and is suitable as a conductive copper material for conductive spring materials used in electronic equipment parts such as autofocus camera modules. Foil and its manufacturing method. The titanium copper foil of the present invention has a foil thickness of 0.1 mm or less, contains 1.5 to 4.5% by mass of Ti, and the balance is made of copper and unavoidable impurities. The surface has a maximum height roughness Rz in a direction parallel to the rolling direction. It is 0.1 μm to 1 μm.

Description

Titanium copper foil, expanded copper products, electronic equipment parts, and autofocus camera modules

The invention relates to a titanium copper foil, expanded copper products, electronic equipment parts, and an autofocus camera module, and particularly relates to a Cu-Ti having good weldability for a conductive spring material suitable for the autofocus camera module and the like. Department of copper alloy foil.

An electronic component called an autofocus camera module is used in a camera lens portion of a mobile phone. On the one hand, the autofocus function of the camera of the mobile phone moves the lens in a certain direction by the elastic force of the material used in the autofocus camera module. Force to move the lens in the direction opposite to the direction of the elastic force of the material. The camera lens is driven by a mechanism similar to the above and performs an auto-focus function.

For conventional autofocus camera modules, Cu-Ni-Sn-based copper alloy foils having a foil thickness of 0.1 mm or less, a tensile strength of 1100 MPa or more, or a 0.2% drop strength have been used. However, with the demand for cost reduction in recent years, the use of a material that is relatively cheaper than a Cu-Ni-Sn-based copper alloy foil has become a Cu-Ti-based copper alloy foil, and this demand is increasing.

In addition, for such a Cu-Ti-based copper alloy foil, for example, Patent Document 1 focuses on the following problem: If the foil thickness is as thin as 0.1 mm or less, if a load is applied to the material to deform it and then the load is removed, relaxation may occur. . In order to solve the above-mentioned problems, Patent Document 1 proposes a solution as follows: Cu-Ti-based copper alloy foil has a thickness of 0.1 mm or less and contains 1.5 to 4.5% by mass of Ti. The balance is composed of copper and unavoidable impurities. The 0.2% yield strength in a direction parallel to the rolling direction is 1100 MPa or more, and the arithmetic average roughness (Ra) in a direction perpendicular to the rolling direction is 0.1 μm or less.

However, since the Cu-Ti alloy contains the element Ti which is easily oxidized under active conditions, a strong oxide film is generated during the aging treatment in the final step. Such a strong oxide film significantly reduces weldability. Therefore, for a Cu-Ti alloy having a comparative thickness of titanium copper plate, strip, and the like, as described in Patent Document 2, chemical polishing (acid washing) is usually performed after aging treatment. ), Further performing mechanical polishing, and removing the oxide film.

To remove the oxide film on the Cu-Ti alloy, chemical polishing is required first. The oxide film of the Cu-Ti alloy containing titanium oxide is very stable to acids. Therefore, in chemical polishing, it is necessary to use a highly corrosive chemical polishing solution such as a solution in which hydrofluoric acid or sulfuric acid is mixed with hydrogen peroxide.

However, when using such a highly corrosive chemical polishing liquid, not only the oxide film will be corroded, but also the non-oxidized part may be corroded, and uneven unevenness or discoloration may occur on the surface after chemical polishing. In addition, there is a possibility that the uniform corrosion may not be performed and an oxide film may remain locally. Therefore, in order to remove unevenness, discoloration, and residual oxide film on the surface, mechanical polishing is performed using a grinding wheel or the like after performing the above-mentioned chemical polishing.

After mechanical grinding, as the final surface treatment, anti-rust treatment is performed and made into board products and strip products. In the rust prevention treatment of titanium copper foil, the same materials as those used for general copper and copper alloy plates and strips, an aqueous solution of benzotriazole (BTA) is used.

[Xizhi technical literature]

Patent Document 1: Japanese Invention Patent No. 5723849.

Patent Document 2: Japanese Invention Patent No. 4068413.

However, unlike the case of a titanium copper plate and a titanium copper bar, in a thin titanium copper foil having a thickness of 0.1 μm or less, for example, it is difficult to perform mechanical polishing to remove an oxide film generated during aging treatment and to improve weldability. There are two reasons for this. The first is related to the titanium copper foil of the mechanical polishing line, and the second is related to the control of the thickness of the plate by the mechanical polishing line.

Regarding the first reason, that is, the titanium copper foil of the mechanical grinding line, when using a grinding wheel, the grinding wheel is hooked on the titanium copper foil with the rotation of the polishing roller. The titanium copper foil may start from the hooking place. fracture. For grinding wheel grinding, the center axis of the cylindrical polishing roller is used as the axis to rotate and The surface of the titanium copper foil was polished. The polishing roller is a resin dispersed with abrasive particles (Sic and other abrasive particles) is fixed on the sponge-like organic fibers. Therefore, the resin block is hooked on the edge of the titanium copper foil in a place with large irregularities. Tension breaks.

Regarding the second reason, the thickness of the plate is controlled by a mechanical polishing line. A cylindrical polishing roll is loaded with a pressure load for polishing, and a titanium copper foil is given a tension by a production line. The pressure load and tension have a periodic vibration component to some extent, and the vibration is called tremor. Depending on the vibration period of the tremor, each vibration may resonate. When the resonance is large, a tatami-like pattern appears on the polishing surface of the object to be mechanically polished due to chattering. The pattern caused by the tremor is called a chatter pattern. This means that the polishing amount varies depending on the pattern, in other words, the polishing amount of the titanium copper foil is not constant. Here, if it is a titanium copper foil, since it is thin compared with a titanium copper plate and a titanium copper bar, the influence by the non-fixation of a grinding | polishing amount is large. That is, when a titanium copper foil is polished by a grinding wheel, thickness variation is large, and if it is used as a spring, the spring characteristics are not stable enough, which is not desirable.

Therefore, compared to titanium copper plates and titanium copper strips, thin titanium copper foils are more difficult to perform mechanical polishing using grinding wheels, and therefore it is difficult to effectively remove oxidation caused by chemical polishing and mechanical polishing of titanium copper plates and titanium copper strips. membrane. Furthermore, in recent years, lead-free solders have been widely used due to health reasons. Such lead-free solders have poor solderability compared with current lead-containing solders.

As a result, there is an undeniable decrease in solderability of the thin titanium copper foil, and in particular, there is a problem that the solder wettability and solderability necessary for manufacturing an autofocus camera module cannot be ensured.

The object of the present invention is to solve the above-mentioned problems, and an object thereof is to provide a thin copper foil having a foil thickness of 0.1 μm or less, which is excellent in solder wettability and solder bonding strength, and is suitable for use in electronic equipment components such as an autofocus camera module. Titanium copper foil for conductive spring material and its manufacturing method.

After intensive discussions by the inventors, the following findings were obtained. In a titanium copper foil having a thickness of 0.1 mm or less, the maximum height roughness Rz of the surface in a direction parallel to the rolling direction is adjusted within a predetermined range, so that an oxide film exists and good solder wetting can be ensured It can also exhibit high bonding strength based on the so-called fixing effect. In addition, the surface roughness Rz described above may be changed by forming oil pits by rolling, and by controlling the final cold rolling process during the manufacture of titanium copper foil, it is possible to produce a maximum surface roughness having a predetermined range. Rz titanium copper foil.

Based on the above findings, the titanium copper foil of the present invention has a foil thickness of 0.1 mm or less, contains 1.5 to 4.5% by mass of Ti, and the balance is made of copper and unavoidable impurities in a direction parallel to the rolling direction. The maximum surface roughness Rz is 0.1 μm to 1 μm.

Here, the titanium copper foil of the present invention preferably has a tensile strength of 1100 MPa or more.

The titanium copper foil of the present invention contains one or more elements selected from the group consisting of 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 expanded copper product of this invention is a thing provided with the titanium copper foil of any one of the said.

An electronic device component of the present invention includes any one of the above-mentioned titanium copper foils.

The electronic device component is preferably an auto-focus camera module.

The autofocus camera module of the present invention includes a lens, a spring member that elastically urges the lens toward an initial position in the direction of the optical axis, and generates an electromagnetic force against the force of the spring member so that the lens can be directed toward the light. For the electromagnetic drive mechanism driven in the axial direction, the spring member is any one of the above-mentioned titanium copper foils.

According to the present invention, it is possible to provide a titanium copper foil having a maximum height roughness Rz of a surface in a direction parallel to the rolling direction of 0.1 to 1 μm and excellent in weldability and adhesion strength. This titanium copper foil is particularly suitable for electronic device parts, and among them, it is particularly suitable for autofocus camera modules.

1‧‧‧Auto Focus Camera Module

2‧‧‧Yoke

2a‧‧‧inner wall

2b‧‧‧outer wall

3‧‧‧ lens

4‧‧‧ Magnet

5‧‧‧ bracket

6‧‧‧coil

7‧‧‧ base

8‧‧‧ frame

9a‧‧‧ (upper) spring part

9b‧‧‧ (lower) spring part

10a‧‧‧ Cover

10b‧‧‧ cover

FIG. 1 is a cross-sectional view showing an autofocus camera module according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view showing the autofocus camera module of FIG. 1.

FIG. 3 is a cross-sectional view showing the operation of the autofocus camera module of FIG. 1.

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

The titanium copper foil according to one embodiment of the present invention has a thickness of 0.1 mm or less and contains 1.5 to 4.5% by mass of Ti. The balance is composed of copper and unavoidable impurities. The maximum height roughness of the surface in the rolling direction Rz is 0.1 μm to 1 μm.

[Ti concentration]

The titanium copper foil of the present invention contains 1.5 to 4.5% by mass of Ti. Titanium-copper dissolves Ti into a Cu matrix by solid solution treatment, and disperses fine precipitates into the alloy by aging treatment, which can increase strength and electrical conductivity. When the Ti concentration is less than 1.5% by mass, the precipitation of the precipitates is insufficient, and the expected strength cannot be obtained. When the Ti concentration exceeds 4.5% by mass, workability is deteriorated, and the material is liable to crack during rolling. Considering the balance between strength and processability, the preferred Ti concentration is 2.9 to 3.5% by mass.

[Other added elements]

The titanium copper foil according to the present invention contains at least one element selected from the group consisting of Ag, B, Co, Fe, Mg, Mn, Mo, Ni, P, Si, Cr, and Zr in a total amount of 0 to 1.0% by mass. , Which can further increase the strength. The total content of these elements is 0, which means that the above elements may not be included. The reason why the upper limit of the total content of the elements is set to 1.0% by mass is that when the content exceeds 1.0% by mass, the workability is deteriorated and the material is liable to crack during rolling.

[tensile strength]

The preferred tensile strength of the titanium copper foil as the conductive spring material of the autofocus camera module is 1100 MPa or more, preferably 1200 MPa or more, and more preferably 1300 MPa or more. In the present invention, the tensile strength in a direction parallel to the rolling direction of the titanium copper foil is measured using the JIS Z2241 (tensile test method for metallic materials) standard as a reference.

[Surface roughness]

The maximum height roughness Rz of the surface of the titanium copper foil of the present invention in a direction parallel to the rolling direction is within a range of 0.1 to 1 μm. Thereby, the required excellent solderability can be ensured, and the bonding strength of the solder can be improved. Therefore, it is particularly advantageous for its manufacture when it is used in an autofocus camera module.

Among them, the reason for specifying the maximum height roughness Rz in a direction parallel to the rolling direction is that when the amount of oil pits during rolling is large and when it is small, the surface roughness significantly changes with the rolling direction. Parallel directions.

In detail, when the roughness Rz in the rolling parallel direction is in the range of 0.1 to 1 μm, the actual surface area will not be too large, so that the solder can be easily wetted and spread, and the solder has excellent adhesion due to moderate unevenness. The maximum height roughness Rz in a direction perpendicular to the rolling direction is also preferably 0.1 to 1 μm.

In other words, when the maximum surface roughness Rz in a direction parallel to the rolling direction is less than 0.1 μm, a fixing effect cannot be obtained, and the adhesiveness is poor. On the other hand, when the maximum surface roughness Rz in a direction parallel to the rolling direction exceeds 1 μm, the time required for solder wetting increases, and solder wettability deteriorates.

From the above viewpoints, it is understood that the maximum surface roughness Rz in the direction parallel to the rolling direction is preferably 0.1 μm to 0.4 μm, and more preferably 0.1 to 0.25 μm.

The maximum height roughness Rz is a roughness curve with a reference length of 300 μm in a direction parallel to or perpendicular to the rolling direction of the titanium copper foil, and can be measured from this curve based on JIS B0601 (2013). .

[Thickness of copper foil]

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

[Production method]

In order to manufacture the titanium copper foil as described above, first, raw materials such as electrolytic copper and Ti are melted in a melting furnace to obtain a desired combined melt. Then, the melt is cast into an ingot. In order to prevent oxidative wear of titanium, melting and casting are preferably performed in an inert gas atmosphere. Thereafter, the ingot is typically implemented in the order of hot rolling, first cold rolling, solution treatment, second cold rolling, aging treatment, and third cold rolling (final cold rolling) in order to obtain the desired thickness and characteristics. Of foil.

The conditions of the hot rolling and the first cold rolling thereafter may be the conditions conventionally used in the production of titanium copper, and there is no particular requirement here. In addition, the solution treatment may be performed in accordance with conventional conditions, for example, at a temperature of 700 to 1000 ° C. for 5 seconds to 30 minutes.

In order to obtain the above-mentioned strength, the rolling reduction in the second cold rolling is preferably set to 55% or more. It is more preferably 60% or more, and even 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. The upper limit of the reduction ratio is not particularly limited in terms of the strength which is the object of the present invention, but it does not exceed 99.8% in industry.

The aging treatment has a heating temperature of 200 to 300 ° C and a heating time of 2 to 20 hours. When the heating temperature is less than 200 ° C, it is difficult to obtain a tensile strength of 1100 MPa or more. Generated when exceeding 300 ℃ Excessive oxide film. When the heating time is less than 2 hours or more than 20 hours, it is difficult to obtain a tensile strength of 1100 MPa or more.

Therefore, in order to obtain the titanium copper foil of the present invention, it is important that in the final cold rolling, a rolling mill using a small-diameter roll is used, the rolling reduction is controlled, and the final pass is rolled with a work roll having a predetermined roughness.

Specifically, since the titanium copper foil is a high-strength hard foil and it is difficult to crush, in the final cold rolling, it is preferable to use a rolling mill having a small diameter roll having a diameter of 30 mm to 120 mm. When the roll diameter is too large, the titanium copper foil will not be crushed until the target thickness is reached, and the increase in the amount of rolling during rolling may easily cause oil pits. When the roll diameter is too small, the rolling speed is limited to Low speed, which may result in reduced productivity. Therefore, the diameter of the roll preferably used is 40 mm to 100 mm.

In the final cold rolling, the surface roughness Rz of the manufactured titanium copper foil is changed by forming oil pits on the surface of the foil. Therefore, the rolling reduction of the final pass is suitably set to 9% to 35%. When the reduction ratio is too large, since the amount of rolling oil drawn between the rolling roll and the material is reduced, the surface roughness Rz of the manufactured titanium copper foil is reduced, resulting in a decrease in solder adhesion. Conversely, when the reduction ratio is too small, the amount of rolling oil drawn between the rolling roll and the material increases, so that the surface roughness Rz of the produced titanium copper foil increases, and the solder wettability decreases. Therefore, the rolling reduction of the final pass is preferably set at 9% to 30%.

In addition, the material of the work roll used as the die steel is high in rolling efficiency at the final pass with a work roll having a surface average roughness Ra of 0.1 μm or less. When the arithmetic mean roughness Ra of the work roll in the final pass is large, the surface roughness Rz of the material tends to exceed 1 μm. The arithmetic average roughness (Ra) of the work roll is a roughness curve with a reference length of 400 μm for the length direction, that is, a direction corresponding to the vertical direction of the rolling direction of the material, and is based on the JIS B0601 standard. Take measurements.

In addition, after the heat treatment, in order to remove the oxide film or oxide layer generated on the surface, pickling and polishing are generally performed. In the present invention, pickling, polishing, and the like of the surface can also be performed after the heat treatment. Furthermore, low-temperature annealing may be performed after the second cold rolling.

After the final cold rolling, antirust treatment can be performed. The rust prevention treatment can be performed under the same conditions as before, and an aqueous solution of benzotriazole (BTA) or the like can be used.

[use]

The titanium copper foil of the present invention can be used for various applications, and is particularly preferably used as a material for electronic device parts such as switches, connectors, sockets, terminals, relays, etc. Among them, it is suitable for electronic devices such as autofocus camera modules. Used as a conductive spring material in parts.

The autofocus camera module includes, for example, a lens, a spring member that elastically urges the lens to an initial position in the optical axis direction, and an electromagnetic force that generates an electromagnetic force against the force of the spring member to drive the lens in the optical axis direction. Electromagnetic drive mechanism. Therefore, this spring member can be used as the titanium copper foil of this invention.

As shown in the example, the electromagnetic drive mechanism has " "" Cylindrical yoke, a coil housed inside the inner peripheral wall of the yoke, a magnet surrounding the coil housed inside the outer peripheral wall of the yoke at the same time.

FIG. 1 shows a cross-sectional view of an example of an auto-focus camera module according to the present invention, FIG. 2 shows an exploded perspective view of the auto-focus camera module of FIG. 1, and FIG. 3 shows the auto-focus camera module of FIG. Sectional view of set of actions.

The autofocus camera module 1 is equipped with " ”Shaped cylindrical yoke 2, magnet 4 mounted on the outer wall of yoke 2, bracket 5 with lens 3 at the center, coil 6 mounted in bracket 5, base 7 with yoke 2, The frame 8 supporting the base 7, the two spring members 9a and 9b supporting the upper and lower support brackets 5, and the two covers 10a and 10b covering the upper and lower portions. The two spring members 9 a and 9 b are the same product, and hold the support bracket 5 from above and below in the same positional relationship, and at the same time function as a power supply path to the coil 6. A current is applied to the coil 6 to move the cradle 5 upward. In addition, in this specification, the expressions "upper and lower" are used appropriately, and they refer to the upper and lower positions in Fig. 1. The upper position indicates the positional relationship from the camera to the subject.

The yoke 2 is made of a magnetic material such as soft iron, "", Which has a cylindrical inner wall 2a and an outer wall 2b. " A ring-shaped magnet 4 is attached (bonded) to the inner surface of the "" -shaped outer wall 2b.

The bracket 5 is a molded product made of a synthetic resin or the like having a cylindrical structure having a bottom surface portion, and supports the lens at a central position, and a preformed coil 6 is adhered to the outside of the bottom surface. The yoke 2 is fitted and assembled on the inner peripheral portion of the base 7 of the rectangular resin molded product, and the entire yoke 2 is fixed by the frame 8 of the resin molded product.

The outermost peripheral portions of any of the spring members 9a and 9b are clamped and fixed by the frame 8 and the base 7, respectively, and the notch portions of the inner peripheral portion are fitted into the bracket 5 and fixed by thermal caulking or the like.

The spring member 9b and the base 7 and the spring member 9a and the frame 8 are fixed by bonding and thermal riveting, and the cover 10b is installed on the bottom surface of the base 7 and the cover 10a is installed on the upper portion of the frame 8, respectively. The spring member 9b is clamped and fixed between the base 7 and the cover 10b, and the spring member 9a is clamped and fixed between the frame 8 and the cover 10a.

A lead wire on one side of the coil 6 passes through a groove provided in the inner peripheral surface of the bracket 5 and extends upward, and is welded to the spring member 9a. The lead on the other side passes through a groove provided in the bottom surface of the bracket 5 and extends downward, and is welded to the spring member 9b.

The spring members 9a and 9b are leaf springs of titanium copper foil according to the present invention. It has elasticity and elastically biases the initial position of the lens 3 in the direction of the optical axis. At the same time, it functions as a power supply path to the coil 6. One part of the outer peripheral part of the spring members 9a and 9b protrudes to the outside, and functions as a power supply terminal.

The cylindrical magnet 4 is magnetized in a radial direction, forming a path through " In the magnetic circuit of the inner wall 2a, the upper surface portion, and the outer wall 2b of the magnetic yoke 2 having a shape of "", the coil 6 is disposed in a gap between the magnet 4 and the inner wall 2a.

The spring members 9a and 9b have the same shape and are mounted in the same positional relationship as shown in Figs. 1 and 2. Therefore, it is possible to suppress shaft misalignment when the bracket 5 moves upward. Since the coil 6 is formed by pressure forming after the winding, the accuracy of the outer diameter of the finished product can be improved, and it can be easily placed in a predetermined narrow gap. The lowermost position of the bracket 5 is pressed against the base 7 and the yoke 2 is pressed at the uppermost position. Therefore, the bracket 5 is provided with an overhead mechanism in the up-down direction to prevent falling off.

FIG. 3 is a cross-sectional view showing that a current is applied to the coil 6 and the bracket 5 including the lens 3 is moved upward for automatic focusing. When a voltage is applied to the power supply terminals of the spring members 9a and 9b, a current flows through the coil 6 to apply an upward electromagnetic force to the bracket 5. On the other hand, the restoring force of the two spring members 9 a and 9 b connected to the bracket 5 acts downward on the bracket 5. Therefore, the distance the bracket 5 moves upward is a position where the electromagnetic force and the restoring force are balanced. Accordingly, the amount of movement of the cradle 5 can be determined by the amount of current applied to the coil 6.

The upper spring member 9a supports the upper surface of the bracket 5 and the lower spring member 9b supports the lower surface of the bracket 5. Therefore, the restoring force acts equally downward on the upper surface and the lower surface of the bracket 5, and the lens 3 can be restored. The shaft misalignment is suppressed to a small extent.

Therefore, when the bracket 5 is moved upward, guidance by ribs or the like is not required or used. Because there is no sliding friction caused by the guidance, the amount of movement of the bracket 5 is completely dominated by the balance of the electromagnetic force and the restoring force, so that the smooth and accurate movement of the lens 3 is achieved. As a result, automatic focusing with less lens misalignment can be achieved.

In addition, the magnet 4 has been described by taking a cylindrical shape as an example, but the present invention is not limited to this. It can also be divided into three to four equal parts for radial magnetization, and it is attached and fixed to the outer wall 2b of the yoke 2. The inner surface.

[Example]

Next, an attempt is made to produce the titanium copper foil of the present invention, and its effects have been confirmed. However, the description herein is merely for the purpose of example, and the present invention is not limited thereto.

[Manufacturing conditions]

The sample was produced as follows. First, 2.5 kg of electrolytic copper was melted in a vacuum melting furnace, and Ti was added to obtain a predetermined concentration of Ti. This molten metal was poured into a mold made of cast iron to produce an ingot having a thickness of 30 mm, a width of 60 mm, and a length of 120 mm.

The ingot was heated at 950 ° C. for 3 hours, and rolled to a thickness of 10 mm. The scale formed under hot rolling was removed with a grinder and polished. The thickness after grinding was 9 mm. Next, the first cold rolling was performed, and this was rolled until the thickness was 1 mm. During the solution treatment, the material was charged into an electric furnace heated to 800 ° C. and held for 5 minutes, and then the sample was placed in a water tank for rapid cooling. Then, a second cold rolling was performed, where the foil thickness was rolled to 0.04 mm at a reduction ratio of 96%. After that, an aging treatment was performed and heating was performed at 280 ° C for 10 hours. Here, as the temperature for the aging treatment, a temperature at which the tensile strength after aging is maximized is selected. Thereafter, the third cold rolling was not performed under the conditions shown in Table 1.

The samples prepared as described above were evaluated as follows.

[Surface roughness]

A roughness curve with a reference length of 300 μm was used in a direction parallel to the rolling direction of the sample, and the curve was measured based on the JIS B0601 (2013) standard.

[Solder wettability ˙solder adhesion]

Soldering test was performed using Pb-free lead M705 solder made by Senju Metal. In the evaluation of solder wettability, "○" was determined when the wet spread radius was 1.5 mm or more, and "×" was determined when the wet spread radius was less than 1.5 mm, based on JIS C60068-2-54. , Welding was performed by welding inspection (SAT-2000 manufactured by RHESCN) in the same procedure as the arc-shaped dip method, and the appearance of the welded portion was observed. The measurement conditions are as follows. As a pretreatment of the sample, acetone was used for degreasing. It was then pickled using a 10 vol% sulfuric acid aqueous solution. The test temperature of the solder is set to 245 ± 5 ° C. The flux is not specified, and GX5 manufactured by Asahi Chemical Research Institute Co., Ltd. can be used. The dipping depth was 2 mm, the dipping time was 10 seconds, the dipping speed was 25 mm / second, and the width of the sample was 10 mm. The evaluation criteria were visually observed under a 20-times solid microscope. The entire surface of the welded part was covered with solder (good), and the part or the entire surface of the welded part was not covered with solder (bad). Further, in the evaluation of solder adhesion, a judgment that the peel strength was 1N or more was ○, and a judgment that the peel strength was less than 1N was x. The peel strength is based on lead-free solder (Sn-3.0% by mass, Ag-0.5% by mass Cu), and titanium-copper foil and pure copper foil with a plating layer (alloy number C1100 specified in JIS H3100 (2012) standard, foil thickness 0.02mm ~ 0.05mm). The titanium copper foil is a strip with a width of 15mm and a length of 200mm. Lead-free solder (diameter 0.4 ± 0.02mm, length 120 ± 1mm) is arranged in an area of 30mm × 15mm at the center with respect to the length direction, so that lead-free solder (diameter 0.4 ± 0.02mm, length 120 ± 1mm) is controlled within the above area, and bonding is performed at a bonding temperature of 245 ° C ± 5 ° C. After joining, the peel strength was measured by performing a peel test at 180 ° at a speed of 100 mm / min. The average value of the load (N) in a 40 mm interval between the peeling displacement from 30 mm to 70 mm is the adhesive strength. An example of the test results in the solder bond strength test is shown in Table 1.

As can be seen from Table 1, in Invention Examples 1 to 22, the final pass was set to a predetermined reduction ratio by using a work roll with a predetermined diameter in the final cold rolling, and the maximum height roughness Rz in the parallel rolling direction was 0.1 to 1.0 μm. As a result, good solder wetting spreadability and solder adhesion are obtained.

On the other hand, in Comparative Example 1, since the rolling reduction in the final pass was small, the maximum height roughness Rz in the rolling parallel direction was increased, and the solder wettability and spreadability were poor. In Comparative Example 2, since the reduction ratio is large, the maximum height roughness Rz in the rolling parallel direction is reduced, and the solder adhesion is decreased.

In Comparative Example 3, since the diameter of the work roll used in the final cold rolling was small, the maximum height roughness Rz in the rolling parallel direction was small, and the solder adhesion was poor. In Comparative Example 4, since the work roll diameter was too large, the maximum height roughness Rz in the rolling parallel direction was large, and the solder wettability decreased.

In Comparative Example 5, since the Ti content was small, the maximum height roughness Rz in the rolling parallel direction was outside the predetermined range, and the sample lacked solder wettability.

In Comparative Examples 6 and 7, since the content of Ti or a minor component was large, cracks occurred during rolling, and samples could not be produced.

From the above, it is understood that the thin titanium copper foil having a foil thickness of 0.1 μm or less according to the present invention can improve solder wettability and solder adhesion strength.

Claims (7)

A titanium copper foil characterized by a foil thickness of 0.1 mm or less, containing 1.5 to 4.5% by mass of Ti, and a balance made of copper and unavoidable impurities; a maximum height of a surface in a direction parallel to a rolling direction The roughness Rz is 0.1 μm to 0.9 μm, wherein the maximum height roughness Rz is a roughness curve with a reference length of 300 μm in a direction parallel to the rolling direction of the titanium copper foil, and JIS B0601 is used from the curve. (2013) The standard is used for measurement. The titanium copper foil according to item 1 of the patent application range, wherein the tensile strength is 1100 MPa or more. The titanium copper foil according to item 1 or item 2 of the patent application scope, which contains a total amount of 0 to 1.0% by mass selected from the group consisting of Ag, B, Co, Fe, Mg, Mn, Mo, Ni, P, and Si , Cr, and Zr. An extended copper product, comprising: the titanium copper foil according to any one of claims 1 to 3 of the scope of patent application. An electronic device component comprising the titanium copper foil according to any one of claims 1 to 3 of the scope of patent application. The electronic device component according to item 5 of the patent application scope, wherein the electronic device component is an auto-focus camera module. An autofocus camera module, comprising: a lens; a spring member elastically urging the lens toward an initial position in an optical axis direction; and generating an electromagnetic force against the force of the spring member to enable the lens An electromagnetic drive mechanism that drives in the direction of the optical axis; wherein the spring member is a titanium copper foil as described in any one of claims 1 to 3 of the scope of patent application.