JP5416681B2 - Touch panel sensor and manufacturing method thereof - Google Patents

Description

  The present invention relates to a touch panel sensor having a transparent conductive film and wiring connected to the transparent conductive film.

  The touch panel sensor, used as an input switch integrated with the image display device, is located on the front of the image display device. Due to its ease of use, the touch panel sensor is widely used for bank ATMs, ticket vending machines, car navigation systems, PDAs, and copy machine operation screens. It is used. Examples of the input point detection method include a resistance film method, a capacitance method, an optical method, an ultrasonic surface acoustic wave method, and a piezoelectric method. Of these, the resistive film method is most widely used because of its low cost and simple structure.

  A resistive film type touch panel sensor is roughly divided into an upper electrode, a lower electrode, and a tail part. A transparent conductive film provided on a substrate (for example, a film substrate) constituting the upper electrode, and a lower electrode are provided. The transparent conductive film provided on the board | substrate (for example, glass substrate) to comprise comprises the structure which opposed the spacer. When the film surface of the touch panel sensor having such a configuration is touched with a finger or a pen, the two transparent conductive films are in contact with each other, and current flows through the electrodes at both ends of the transparent conductive film. The touched position is detected by measuring the voltage division ratio due to the resistance.

  In the process of manufacturing the touch panel sensor, the wiring such as the lead wiring for connecting the transparent conductive film and the control circuit and the metal wiring for connecting the transparent conductive film is generally conductive paste such as silver paste or conductive ink. Is formed by printing with an inkjet or other printing method. However, wiring made of pure silver or a silver alloy has poor adhesion to glass, resin, etc., and causes aggregation due to aggregation on the substrate at the connection portion with an external device, leading to defects due to increased electrical resistance or disconnection. There is a problem such as.

  Furthermore, the touch panel sensor is a sensor that senses indentation by a human finger or the like, and temporarily undergoes minute deformation due to stress applied during touch. Due to repeated use of the touch panel, this minute deformation repeatedly occurs, and stress is repeatedly applied to the wiring. Accordingly, the wiring is particularly required to have durability (resistance to stress). However, it is difficult to say that the wiring formed using a conductive paste made of pure silver or a silver alloy has sufficient durability, and the wiring is easily damaged during use of the touch panel. If the wiring is damaged, the electrical resistance of the wiring increases and a voltage drop occurs, so that the accuracy of position detection of the touch panel sensor tends to decrease. Further, when the pen touch method is adopted, it is necessary to reduce the pitch of the wiring. However, when the paste is used, it is difficult to reduce the pitch because it is formed by a coating method.

  On the other hand, it is also conceivable to apply pure Al having a sufficiently low electrical resistivity to the wiring material. However, when pure Al is used as the wiring material, there arises a problem that insulating aluminum oxide is formed between the transparent conductive film and the pure Al film in the touch panel sensor, and electrical conductivity cannot be ensured. Therefore, in order to prevent Al oxidation and ensure electric conductivity, a barrier metal layer made of a refractory metal such as Mo or Ti is used as a base layer by interposing between a transparent conductive film and a pure Al film. A method of using an Al—Nd alloy containing Nd having excellent heat resistance instead of pure Al has been proposed. Further, the applicant of the present invention shows an Al film containing a predetermined amount of Ni and / or Co as an Al film that exhibits low electrical resistance even when directly connected to a transparent conductive film, and that hardly increases in electrical resistance or breaks over time. A Ni / Co alloy film (single-layer wiring material) is disclosed in Patent Document 1.

JP 2009-245422 A

  An object of the present invention is to provide a highly reliable touch panel sensor that is particularly excellent in durability in the vertical direction such as an indentation load and that is less likely to cause disconnection or increase in electrical resistance over time.

The touch panel sensor of the present invention capable of solving the above problems is a touch panel sensor having a transparent conductive film and a wiring connected to the transparent conductive film, wherein the wiring is in order from the substrate side, a refractory metal film, and an Al alloy. The Al alloy film contains 0.05 to 1 atomic% of rare earth elements, has a hardness of 2 to 3.5 GPa, and is present in the Al alloy structure. The density of the grain boundary triple points to be produced is summarized as 2 × 10 ⁸ pieces / mm ² or more.

  In a preferred embodiment of the present invention, the rare earth element is one or more elements selected from the group consisting of Nd, Gd, La, Y, Ce, Pr and Dy.

  In a preferred embodiment of the present invention, the transparent conductive film is made of indium tin oxide (ITO) or indium zinc oxide (IZO).

  According to the present invention, in a touch panel sensor using a wiring material in which a refractory metal film is disposed above and below an Al alloy film containing a rare earth element as a touch panel sensor wiring, the hardness and grain boundary of the Al alloy film Since the triple point density is controlled appropriately, it is particularly excellent in durability in the vertical direction such as indentation load, and it is difficult to cause disconnection and increase in electrical resistance over time. Could be provided. The present invention is effective for various touch panels, but is preferably used for a contact type touch panel sensor that operates by pressing a portion displayed on a screen such as an ATM of a financial institution such as a bank or a vending machine such as a station or a restaurant. It is done.

  The present inventors have widely used wiring materials as touch panel sensor wirings, that is, Al alloy films containing rare earth elements (hereinafter sometimes abbreviated as Al-rare earth element alloy films or simply Al alloy films). In touch panel sensors that have wiring materials in which high melting point metal films such as Mo are laminated above and below, especially for vertical deformation caused by indentation load applied when touched with a human finger or pen In order to provide a wiring material that has excellent resistance, can prevent disconnection and peeling, and can prevent an increase in electrical resistance with time, it has been studied repeatedly. As a result, the inventors have found that the intended purpose can be achieved if an Al alloy film having a predetermined hardness and grain boundary density is used as the Al-rare earth element alloy film, and the present invention has been completed.

That is, the characteristic part of the present invention is that the Al-rare earth alloy film for wiring used together with the refractory metal film has a hardness of 2 to 3.5 GPa and a density of grain boundary triple points existing in the Al alloy structure. An Al alloy film of 2 × 10 ⁸ pieces / mm ² or more is employed.

  First, the hardness of the Al-rare earth alloy film is 2 to 3.5 GPa. The touch panel excels in deformability (followability) when touched (during use), especially when the screen is strongly touched with a pen or finger, an excessive load is applied, and stress is temporarily applied to the sensor edge. Even if the wiring is deformed or deteriorates due to concentration, it is required to have durability in the vertical direction so that the wiring is not broken, broken or peeled off. The hardness is set from such a viewpoint, and is set in consideration of the balance with the hardness of the refractory metal film disposed above and below the Al alloy film.

  Specifically, if the wiring material that makes up the wiring is too soft, the wiring will be repeatedly deformed due to stress concentration, resulting in deterioration of the wiring, resulting in failure such as breakage or peeling, resulting in increased electrical resistance. There is. On the other hand, if the wiring material is too hard, it is difficult for deformation to occur due to the indentation load, so that degradation such as microcracking or peeling may occur. When a laminate of an Al alloy film and a refractory metal film is used as a wiring material as in the present invention, the balance with the hardness of the refractory metal film is further taken into account when setting the hardness of the Al alloy film. It is necessary to control the upper limit of the hardness of the Al alloy film to be almost the same as the hardness of the refractory metal constituting the refractory metal film, while the lower limit of the hardness of the Al alloy film is the high melting point metal. It is better that the difference between hardness and metal is not so large. Based on such a viewpoint, in the present invention, the hardness of the Al alloy film is set to 2 GPa or more and 3.5 GPa or less. Preferably it is 2.5 GPa or more and 3.3 GPa or less. The hardness of the Al alloy film is a value measured by the method described in the examples described later.

Further, the Al alloy film used in the present invention satisfies the density of grain boundary triple points existing in the Al alloy structure (hereinafter sometimes abbreviated as triple point density) of 2 × 10 ⁸ pieces / mm ² or more. Is. As described above, in the present invention, it is necessary to control the hardness of the Al alloy film within a predetermined range. Usually, the hardness is closely related to the triple point density, and the rare earth element content is within the range of the present invention. When it is (1 atomic% or less), the hardness tends to increase as the triple point density increases. In the present invention, the triple point density is set to 2 × 10 ⁸ pieces / mm ² or more from the viewpoint of securing the lower limit (2 GPa) of the hardness of the Al alloy film. Preferably it is 2.4 × 10 ⁸ pieces / mm ² or more. The upper limit of the triple point density is preferably 8.0 × 10 ⁸ pieces / mm ² in consideration of the efficiency of sputtering film formation. The triple point density of the Al alloy film is a value measured by the method described in the examples described later.

  The hardness and triple point density of the Al alloy film that characterize the present invention have been described above.

  The Al alloy film used in the present invention contains 0.05 to 1 atomic% of rare earth elements, and the balance is Al and inevitable impurities. In the present invention, the composition of the Al alloy film to be used is not characterized, and the Al alloy film containing rare earth elements has heat resistance and is known to be used as a wiring material. From the viewpoint of providing a material suitable for a touch panel sensor, an Al alloy film whose hardness and triple point density are controlled has not been disclosed so far. The lower limit and upper limit of the rare earth element content are determined in order to ensure the range of hardness and triple point density specified in the present invention. As shown in the examples described later, as the rare earth element content decreases, the hardness tends to decrease, and the rare earth element content is lower than the lower limit specified in the present invention. At least one is out of the scope of the present invention. On the other hand, as the rare earth element content increases, the hardness also tends to increase. When the rare earth element content exceeds the upper limit specified in the present invention, at least one of the hardness and the triple point density is It is out of range.

  As the rare earth element used in the present invention, an element obtained by adding Sc (scandium) and Y (yttrium) to a lanthanoid element (a total of 15 elements from La of atomic number 57 to Lu of atomic number 71 in the periodic table). Groups. In the present invention, these elements can be used alone or in combination of two or more. The rare earth element content is a single amount when contained alone, and when two or more kinds are contained, Total amount. Preferred rare earth elements are one or more elements selected from the group consisting of Nd, Gd, La, Y, Ce, Pr, and Dy.

  In the present invention, a wiring material in which a refractory metal film is laminated on the top and bottom of the Al alloy film is used. As described above, the refractory metal film is widely used as an underlayer of the Al alloy film in order to prevent the oxidation of Al. In the present invention, Mo, Ti, Cr, W, or an alloy thereof is used. Can do. The composition of the refractory metal films disposed above and below the Al alloy film may be the same or different at the top and bottom.

  The preferable thickness of the Al alloy film is about 150 to 600 nm, and the preferable thickness of the refractory metal film is about 30 to 100 nm.

  In the present invention, in order to obtain an Al alloy film whose hardness and triple point density are appropriately controlled, in addition to using an Al alloy film containing a predetermined rare earth element, Heat treatment (annealing) is preferably performed within a range of ˜230 ° C. The touch panel manufacturing process generally suffers from a thermal history of about room temperature to about 250 ° C. However, when the annealing temperature is increased, the hardness and triple point density decrease due to precipitation of rare earth elements and grain growth of Al alloy. It becomes like this. Specifically, an appropriate annealing temperature may be set in accordance with the amount of rare earth element added, but it is more preferably 150 to 230 ° C.

  Furthermore, in the present invention, it is preferable to form the Al alloy film by sputtering from the viewpoints of thinning and homogenizing the alloy components in the film and easily controlling the amount of added elements. In the sputtering method, it is preferable to control the film forming temperature during sputtering to approximately 180 ° C. or lower and the Ar gas pressure to approximately 3 mTorr or lower. As the substrate temperature and the film formation temperature are higher, the film quality of the formed film becomes closer to the bulk, a dense film tends to be formed, and the hardness of the film tends to increase. Further, as the Ar gas pressure is increased, the density of the film decreases and the hardness of the film tends to decrease. Such adjustment of the film forming conditions is also preferable from the viewpoint of suppressing the sparseness of the film structure and easily causing corrosion.

  In the present invention, there is a feature in the wiring composed of a laminated layer of an Al alloy film and a refractory metal film connected to the transparent conductive film, and the other configurations are not particularly limited, and a known configuration usually used in the field of touch panel sensors is used. Can be adopted.

  For example, a resistive film type touch panel sensor can be manufactured as follows. That is, after forming a transparent conductive film on a substrate, resist coating, exposure, development, and etching are sequentially performed, and then a refractory metal film, an Al alloy film, and a refractory metal film are sequentially formed, and resist coating, Exposure, development, and etching are performed to form a wiring, and then an insulating film or the like that covers the wiring is formed to form an upper electrode. Also, after forming a transparent conductive film on the substrate, photolithography is performed in the same manner as the upper electrode, and then the wiring made of a refractory metal film, an Al alloy film, and a refractory metal film, as in the case of the upper electrode. Then, an insulating film covering the wiring is formed, and a micro dot spacer is formed to form a lower electrode. Then, the touch panel sensor can be manufactured by laminating the upper electrode, the lower electrode, and the tail portion separately formed.

  The said transparent conductive film is not specifically limited, As a typical example, what consists of indium tin oxide (ITO) or indium zinc oxide (IZO) can be used. In addition, as the substrate (transparent substrate), for example, glass, polycarbonate, or polyamide can be used as a commonly used substrate. For example, the substrate of the lower electrode that is a fixed electrode is made of glass. And a polycarbonate film or the like can be used for the substrate of the upper electrode that needs flexibility.

  The touch panel sensor of the present invention can also be used as a touch panel sensor such as a capacitive method or an ultrasonic surface acoustic wave method in addition to the resistive film method.

  Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited by the following examples, and can be implemented with modifications within a range that can be adapted to the above and the following points, They are all included in the technical scope of the present invention.

Example 1
A non-alkali glass plate (plate thickness 0.7 mm, diameter 4 inches) is used as a substrate, and the surface of the substrate is subjected to DC magnetron sputtering, as shown in Table 1 below, and the type and content of rare earth elements (unit is atomic%) Then, Al alloy films (thicknesses are both about 500 nm) having different balances: Al and inevitable impurities were formed. Before film formation, the atmosphere in the chamber is once set to an ultimate vacuum of 3 × 10 ⁻⁶ Torr, and then a disk type target having the same component composition as each Al alloy film is used. It carried out on the conditions shown in. Next, the Al alloy after film formation was heat-treated at various annealing temperatures shown in Table 1 for 30 minutes in a nitrogen atmosphere. In Table 1, “-” means no heating (that is, room temperature). In addition, the composition of the formed Al alloy film was confirmed by inductively coupled plasma (ICP) mass spectrometry.
(Sputtering conditions)
Ar gas pressure: 2 mTorr
Ar gas flow rate: 30sccm
・ Sputtering power: 260W
・ Deposition temperature: Room temperature

  Using the Al alloy film obtained as described above, the hardness test of the film with a nanoindenter was performed. In this test, continuous stiffness measurement was performed using an Nanochip XP (analysis software: Test Works 4) manufactured by MTS, using an XP chip. The indentation depth was 300 nm, the average value of the results of measuring 15 points under the conditions of excitation vibration frequency: 45 Hz and amplitude: 2 nm was determined.

  Further, the Al alloy film obtained as described above is observed with a TEM at a magnification of 150,000 times, and Al present in the grain boundary triple point is observed in the measurement field (one field is 1.2 μm × 1.6 μm). The density of the alloy (triple point density) was measured. The measurement was performed with a total of three fields of view, and the average value was defined as the triple point density of the Al alloy.

  For a sample in which a pure Al film was formed instead of the Al alloy film, the hardness and triple point density were measured in the same manner as described above.

These results are also shown in Table 1. In Table 1, “E + 07” means 10 ⁷ . For example, No. 1 in Table 1. “9.0E + 07” of 1 means 9.0 × 10 ⁷ .

  In Table 1, No. 5 to 18 and 37 to 39 are examples of Al alloy films containing Nd as a rare earth element. When the annealing temperature is the same, the hardness and triple point density tend to increase as the Nd amount increases [for example, when the annealing temperature is room temperature (−), No. 5, 9, 13, 37], it can be seen that it is effective to set the upper limit of the Nd content to 1 atomic% in order to control the hardness and the triple point density within a predetermined range. Further, even when the Nd amount is the same, when the annealing temperature becomes higher than the preferred range of the present invention, the hardness and the triple point density tend to decrease [for example, when the annealing temperature is 250 ° C., no. 8, 12, 17, 18], it can be seen that it is effective to control the upper limit of the annealing temperature to 230 ° C. in order to control the hardness and triple point density within a predetermined range.

  In Table 1, No. 19 to 36 are examples using an Al alloy film containing a rare earth element other than Nd. All of these materials contain the rare earth element content defined in the present invention, and are manufactured by controlling the annealing temperature within the preferred range of the present invention, so the hardness and triple point density are controlled within the scope of the present invention. It was. Further, it has been confirmed by experiments that the same experimental results as those of Nd described above are observed when the rare earth elements other than Nd are used (not shown in Table 1).

  From these results, when the Al-rare earth element alloy film of the present invention is used, it is possible to provide a highly reliable touch panel sensor that is excellent in durability in the vertical direction and hardly causes disconnection or an increase in electrical resistance over time. Is highly expected.

  In contrast, no. Nos. 1 to 4 are examples of pure Al containing no rare earth element, and it was not possible to control the hardness and triple point density specified in the present invention, no matter how the annealing temperature was controlled.

Claims (5)

In the touch panel sensor having a transparent conductive film and a wiring connected to the transparent conductive film,
The wiring is composed of a refractory metal film, an Al alloy film, and a refractory metal film in order from the substrate side.
The Al alloy film contains 0.05 to 1 atomic% of rare earth elements, has a hardness of 2 to 3.5 GPa, and the density of grain boundary triple points existing in the Al alloy structure is 2 × 10 ⁸ pieces / Touch panel sensor characterized by being ² mm or more. The touch panel sensor according to claim 1, wherein the Al alloy film is formed by annealing at room temperature to 230 ° C. after sputtering. The rare earth element, touch panel sensor according Nd, Gd, La, Y, Ce, to claim 1 or 2 is one or more elements selected from the group consisting of Pr and Dy. The transparent conductive film, a touch panel sensor according to any one of claims 1-3 made of indium tin oxide (ITO) or indium zinc oxide (IZO). It is a manufacturing method of the touch panel sensor in any one of Claims 1, 3, or 4,
A method of manufacturing a touch panel sensor, comprising annealing at room temperature to 230 ° C. to form an Al alloy film after sputtering.