JP6177298B2 - Metal mask material and metal mask - Google Patents

Description

  The present invention relates to a metal mask material and a metal mask used for manufacturing an organic EL display.

  Compared with the current mainstream liquid crystal display among flat panel displays, the organic EL display has a simple structure that allows the product to be thinner, displays fast moving images smoothly, and has a wider viewing angle. have. This organic EL display has already been mass-produced in small devices such as portable terminals, and is being put to practical use in large displays as a favorite of next-generation displays.

Methods for producing an EL (light emission) layer of an organic EL display are roughly classified into a vapor deposition method and a printing method. The vapor deposition method is a method in which an EL substance heated and evaporated in a vacuum is attached to the surface of the substrate as a thin layer. The printing method is a method for producing an EL layer on the surface of a substrate by printing. The vapor deposition method further includes a type that emits three colors of RGB (red, green, and blue) and a type that emits white light from the EL layer.
In the vapor deposition method, there is a color patterning process in which a metal mask is placed between the vapor deposition source and the substrate in order to produce the EL layer in a predetermined pattern at a predetermined position on the substrate. The metal mask is made of a metal plate or foil having an opening corresponding to the pattern of the EL layer. The EL material evaporated from the evaporation source and released in vacuum reaches the metal mask, and the EL material that has passed through the opening of the metal mask adheres to the substrate to form an EL layer having a predetermined pattern.

By the way, in the color patterning process, the temperature of the metal mask may rise to about 100 ° C. due to the radiant heat from the vapor deposition source, and further, the organic material having a high temperature attached to the surface of the metal mask. In order to maintain the accuracy of the forming position, it is necessary to use a material having a thermal expansion equal to or less than that of the substrate for the metal mask. In particular, since the EL layer pattern of the type that emits three colors of RGB needs to be formed for each of the three colors of RGB, it is important to suppress the shift of the molding position due to the expansion of the metal mask.
As for the thickness of the metal mask, a foil of 0.02 to 0.08 mm is mainly used in a type that emits three colors of RGB, and a plate of 0.08 to 0.25 mm is mainly used in a type that emits white light from an EL layer. .

As another problem in the color patterning process in the type of emitting three colors of RGB, there is a case where the organic material to be molded on the substrate is displaced and a problem such as uneven color of the image occurs. In this step, the organic material is deposited on the substrate through a hole in the metal mask from a single deposition source. For this reason, when the metal mask is thick, when the incident angle of the organic material becomes shallow at a position away from the vapor deposition source, the aperture wall becomes a shadow, and the pattern shape of the organic material is formed into a shape different from that of the aperture. It becomes difficult to maintain accuracy. This is called a shadowing effect and can be improved by making the metal mask thinner.
On the other hand, if the metal mask is thinned to avoid the above problem, the metal mask may be distorted during handling, or an organic material may be deposited on the metal mask to increase the weight, thereby causing distortion in the metal mask. In order to avoid such a problem, it is necessary to maintain the strength of the metal mask, and there is a limit to reducing the thickness.

  Therefore, as a method of achieving both the strength of the metal mask and the shape accuracy of the opening portion, a technique (Patent Document 1) for preventing the bending of the thin metal mask by partially providing a reinforcing metal wire, or forming the opening portion. Techniques (Patent Documents 2 and 3) are disclosed in which a single metal mask is manufactured by bonding a support layer separate from the support layer while reducing the thickness of the layer. Moreover, the technique (patent document 4) which controls surface roughness and improves an etching process precision is disclosed.

Japanese Patent Laid-Open No. 10-50478 Japanese Patent No. 4126648 JP 2004-039628 A JP 2010-214447 A

  However, in the case of the technique disclosed in Patent Document 1, since the organic material does not adhere to the portion behind the reinforcing metal wire, a phenomenon similar to the shadowing effect occurs, and the shape of the organic material formed on the substrate The accuracy becomes worse. In the case of the techniques disclosed in Patent Documents 2 and 3, two metal foils are required to manufacture one metal mask, and these metal foils need to be joined with high accuracy. The metal mask molding process becomes complicated, leading to an increase in manufacturing cost.

  Therefore, as a solution to the above-described problem, a method is known in which a hole is formed after the periphery of the hole is thinned by half etching while using a material having a thickness that can maintain strength. Thereby, while using one metal foil, the shadowing effect can be suppressed, and further, the strength of the material can be secured and the occurrence of distortion due to the adhesion of the organic material can be suppressed. In addition, the manufacturing cost can be reduced by manufacturing the opening portion by an etching method as compared with the case of directly manufacturing a mask (foil, plate) having a predetermined opening portion by a plating method.

On the other hand, in the process of manufacturing a metal mask by a method such as etching from a metal mask material, the presence or absence of defects on the surface of the metal mask material is monitored visually or with a CCD camera or the like, and the defective metal mask material is removed from the process. .
In addition, a shielded vapor deposition material that does not reach the substrate is deposited on the portion other than the opening of the metal mask, but is washed and repeatedly used as a metal mask. The presence or absence of defects on the surface of the metal mask that is repeatedly used is also monitored visually or with a CCD camera or the like, and the defective metal mask is removed from the process.

Metal mask defects include foreign matter adhering to the surface, local discoloration, and poor gloss, and these minute defects that cannot be visually confirmed are inspected with an image obtained by enlarging the surface with a CCD camera or the like. . Of the defects, foreign matter having a color tone different from that of the metal mask material and local discoloration can be easily detected. Further, a foreign matter having the same color tone as that of the metal mask material, for example, a metal piece, is more difficult to detect than a foreign matter having a different color tone or local discoloration. Furthermore, local gloss defects are more difficult to identify on the CCD camera image because the outline is unclear and the tone is the same as the metal mask material.
Therefore, if the surface irregularities and patterns of the metal mask material are conspicuous, minor and weak defects such as the above-mentioned local gloss failure are difficult to detect by visual inspection, and even a CCD camera image may not be detected. In this regard, although the technique described in Patent Document 4 improves the etching processing accuracy by appropriately roughening the surface roughness, the above-described local gloss failure can be accurately detected by the CCD camera image due to the unevenness of the surface. It is not enough to detect well.

  Accordingly, it is an object of the present invention to provide a metal mask material and a metal mask that can improve the etching processing accuracy and can detect defects of itself with high accuracy.

As a result of extensive research by the present inventors, by controlling the 60 degree glossiness G60 within a predetermined range, it is possible to improve the etching processing accuracy and provide appropriate surface irregularities that can accurately detect its own defects. I found out that I can.
That is, the metal mask material of the present invention comprises a rolled foil of an Fe—Ni alloy containing Ni and Co in a total amount of 30 to 45% by mass, Co in an amount of 0 to 6% by mass, and the balance Fe and inevitable impurities. The thickness t is 0.02 to 0.08 mm, the arithmetic average roughness Ra measured in accordance with JIS-B0601 in the rolling parallel direction and the rolling perpendicular direction is 0.01 to 0.20 μm, and the rolling parallel direction and the rolling perpendicular direction. The 60 degree glossiness G60 measured according to JIS-Z8741 is 200 to 600.

  The metal mask of the present invention is made using the metal mask material.

  ADVANTAGE OF THE INVENTION According to this invention, while improving an etching process precision, the metal mask material and metal mask which can detect an own defect accurately can be provided.

It is a figure which shows the optical microscope image of the pattern by the crystal grain parting after finish rolling.

  Hereinafter, a metal mask material according to an embodiment of the present invention will be described. Unless otherwise specified, “%” represents “mass%”.

(Alloy components)
Glass is used for the organic EL substrate, and it is necessary to adjust the alloy components so that the thermal expansion coefficient of the metal mask placed on the substrate is 10 × 10 ⁻⁶ / ° C. or less. . The thermal expansion coefficient can be adjusted by adding a predetermined concentration of Ni and / or Co to Fe, and Fe-- in which Ni and Co are 30 to 45% in total and Co is 0 to 6%. A Ni-based alloy was used. If the total concentration of Ni and Co and the concentration of Co are out of this range, the thermal expansion coefficient of the metal mask becomes larger than the thermal expansion coefficient of the glass, which is not suitable. Preferably, Ni and Co are 34 to 38% in total, and Co is 0 to 6%.

(Thickness)
The thickness of the metal mask material of the present invention is 0.02 to 0.08 mm, and preferably 0.02 to 0.04 mm. When the thickness of the metal mask material is less than 0.02 mm, the handling property is inferior, and the organic mask is likely to be distorted or deformed by the deposition of the organic material, so that the positional accuracy of the organic material formed on the substrate is improved. May be inferior. When the thickness of the metal mask material exceeds 0.08 mm, the shadowing effect may be remarkably generated.

(Arithmetic mean roughness Ra)
The arithmetic average roughness Ra measured on the surface of the metal mask material of the present invention according to JIS-B0601 in the rolling parallel direction and the perpendicular direction of rolling is 0.01 to 0.20 μm, preferably 0.01 to 0.08 μm. It is. If Ra is less than 0.01 μm and the surface roughness is excessively reduced, the surface is smooth, and slippage is caused by the material guide rolls (foil passing rolls, thread passing rolls) of the line for producing the metal mask by etching from the metal mask material. Scratches are likely to occur. Also, if Ra exceeds 0.20 μm and the surface roughness is excessively rough, it is difficult to identify a local gloss failure with an unclear outline and the same color tone as the metal mask material on the CCD camera image. Become.

  Moreover, it is preferable that the maximum height Ry which measured the surface of the metal mask material of this invention according to JIS-B0601 in the rolling parallel direction and the rolling orthogonal direction is 0.1-2.0 micrometers.

(60 degree gloss G60)
60 degree glossiness G60 measured according to JIS-Z8741 in the rolling parallel direction and rolling perpendicular direction of the surface of the metal mask material of the present invention is 200 to 600, and preferably 400 to 600. If the G60 of the metal mask material is less than 200, the surface unevenness and pattern are conspicuous, the outline is unclear, and it is difficult to detect a local gloss failure with the same color tone as the metal mask material in the CCD camera image. become. If the G60 of the metal mask material exceeds 600, the surface becomes too smooth, so surface control factors (for example, the shape and surface roughness of the rolling roll, the viscosity of the rolling oil, the surface of the rolling roll and the surface of the metal mask material) G60 changes greatly due to variations in the thickness of the oil film to be formed and the surface roughness of the metal mask material before rolling, making it difficult to ensure surface uniformity, resulting in poor quality in appearance (for example, streaks). Or unevenness).

(Manufacturing method of metal mask material)
The metal mask material of the present invention can be manufactured, for example, as follows, but is not intended to be limited to the following method.
First, the raw material is melted in a melting furnace to obtain a molten metal having the above-mentioned Fe—Ni alloy composition. At this time, if the oxygen concentration of the molten metal is high, the amount of crystallized substances such as oxides may increase, which may cause etching defects. Increase the cleanliness of the molten metal by such methods as casting into an ingot. Then, after hot rolling and grinding and removal of the oxide layer, cold rolling and annealing are repeated to finish to a predetermined thickness. For cold rolling and annealing, for example, intermediate recrystallization annealing, intermediate cold rolling, final recrystallization annealing, finish cold rolling, and strain relief annealing can be sequentially performed.

(Intermediate recrystallization annealing)
Grain size number GSNO. It is preferable to perform recrystallization annealing (number specified in JIS G 0551 “steel—microscopic test method for crystal grain size”) of 9.0 to 11.0. Grain size number GSNO. By increasing the value, a metal structure in which (200) is oriented is obtained in the final recrystallization annealing. The metal structure in which (200) is oriented in the final recrystallization annealing is unlikely to cause a crystal grain breakage pattern in finish cold rolling, and the 60 degree gloss G60 can be reliably increased to 200 or more. Grain size number GSNO. Is small, that is, when the crystal grains are large, a metal structure in which (200) is sufficiently oriented may not be obtained by final recrystallization annealing. Is set to 9.0. On the other hand, the crystal grain size number GSNO. Is too large, that is, if the crystal grains are too small, unrecrystallized parts are dispersed in the recrystallized structure, which causes non-uniform recrystallized structure in the final recrystallization annealing. Particle size number GSNO. Is set to 11.0.
Here, when the temperature of the intermediate recrystallization annealing is increased or the time is increased, GSNO. When the temperature is decreased or the time is shortened, GSNO. Will grow.

(Intermediate cold rolling)
It is preferable to perform cold rolling with a workability defined by the following formula of 85% or more.
Degree of processing = {(sheet thickness before rolling−sheet thickness after rolling) / (sheet thickness before rolling)} × 100 (%)
By increasing the workability, a metal structure in which (200) is oriented is obtained by the final recrystallization annealing, and the 60 ° glossiness G60 is increased as described above. If the degree of work is small, a metal structure in which (200) is sufficiently oriented may not be obtained by final recrystallization annealing, so the lower limit of the degree of work is set to 85%. On the other hand, if the degree of work is too high, the degree of orientation of (200) in the final recrystallization annealing does not increase any more, and the hardness increases and the productivity decreases, so the upper limit of the degree of work is 90%.

(Final recrystallization annealing)
Also in the final recrystallization annealing, the grain size number GSNO. When recrystallization annealing is performed at a value of 9.0 to 11.0, the 60 ° gloss G60 can be reliably increased to 200 or more for the same reason as in the case of intermediate recrystallization annealing.

(Finish cold rolling)
The surface properties (arithmetic average roughness Ra and 60 degree gloss G60) of the metal mask material vary depending on the surface irregularities generated by finish cold rolling. In finish cold rolling, surface irregularities are generated by transferring the rolling rolls to the material. Further, surface irregularities are also generated by the rolling oil flowing between the rolling roll and the material in the finish cold rolling to generate oil pits. In other words, an oil film exists between the rolling roll and the material, and in the part where the oil film is locally thick, the contact between the rolling roll and the material becomes insufficient, and the rolling roll eyes are not transferred and exhibit pit-like irregularities. This is the oil pit. As a cause of locally increasing the rolling oil, there are unevenness on the surface of the rolling roll and variation in workability of the material. In particular, when the surface becomes smooth, the sensitivity of the influence of the variation increases, and the variation in the thickness of the oil film tends to occur.

Further, the crystal grains are divided by finish cold rolling to form a pattern, which greatly affects the 60-degree glossiness G60.
FIG. 1 shows an optical microscope image of a pattern formed by crystal grain division after finish cold rolling. The pattern by the crystal grain division is intermittently distributed in a line along the rolling direction RD, and each pattern is a streak extending in a direction intersecting with the rolling direction RD as indicated by an arrow in FIG. In FIG. 1, two clear patterns (two rows) are generated along the rolling direction RD.
Here, the code | symbol G of FIG. 1 shows one oval crystal grain extended in the rolling direction RD by cold rolling. It can be seen that the division pattern is generated inside the crystal grain G.
In FIG. 1, since the focus of the optical microscope image is adjusted to the crystal grain cutting pattern, surface irregularities such as transfer of oil pits and rolling rolls that are significantly different from the crystal grain cutting pattern are shown in FIG. It is not shown.

Since the cold rolling of the foil is performed at a high workability from the viewpoint of productivity, the crystal grains are elongated and are easily divided. The fragmented crystal grains appear as a pattern on the surface as shown in FIG. 1, resulting in a decrease in the 60 ° glossiness G60.
Here, the ease with which the crystal grains are divided is affected by the orientation of the crystal grains, and the ease with which the crystal grains are divided differs depending on the orientation of the crystal grains. This is because the deformability of crystals varies depending on the crystal orientation. The main diffraction peaks in the alloy system of the metal mask material of the present invention are the (200) plane, the (220) plane, the (311) plane and the (111) plane, with the (200) plane having the most crystal grains. It is difficult to divide. Therefore, as described above, by orienting in the (200) plane by the intermediate recrystallization annealing and the final recrystallization annealing, it becomes difficult for the crystal grains to be divided in the finish cold rolling, and the 60 degree gloss G60 is set to 200 or more. be able to.

The degree of finish cold rolling is preferably 70% or more. The higher the degree of processing, the smaller the crystal grain division pattern produced by finish cold rolling due to the effect of compression processing, and the 60 ° gloss G60 increases. On the other hand, if the degree of work is too high, the effect of weakening the crystal grain division pattern by compression is saturated, and the hardness is increased and the productivity is lowered, so the upper limit of the degree of work is 90%.
Here, cold rolling is performed using a rolling roll having a small diameter as much as possible, so that the rolling oil is less involved and the surface of the rolled material becomes smooth. That is, the use of a small-diameter rolling roll can suppress the generation of oil pits, and can further reduce the crystal grain division pattern. Further, like the rolling roll diameter, by lowering the rolling speed, rolling oil is less involved and the surface of the rolled material becomes smooth. That is, when the rolling speed is reduced, the generation of oil pits can be suppressed and the crystal grain cutting pattern can be further reduced.
Note that the diameter and rolling speed of the cold rolling roll vary depending on the thickness and width of the metal mask material to be manufactured, and the diameter and rolling speed of the rolling roll may be appropriately set within a range in which Ra and G60 can be controlled. However, the rolling speed is preferably 60 m / min or less.

  Since the oil pit and the crystal grain cutting pattern are caused by different factors, it is preferable to set production conditions that can suppress both of the oil pit and the crystal grain cutting pattern while confirming the occurrence of the oil pit and the crystal grain cutting pattern.

(Strain relief annealing)
Furthermore, it is preferable to finally perform strain relief annealing at 200 to 400 ° C. The time for strain relief annealing can be, for example, 1 to 24 hours.

EXAMPLES Examples of the present invention will be described below, but these are provided for better understanding of the present invention and are not intended to limit the present invention.
(1) Production of metal mask material A raw material obtained by adding 36% by mass of Ni to Fe was melted by vacuum induction melting to cast an ingot having a thickness of 50 mm. This is hot rolled to 8 mm, and the surface oxide film is ground and removed, and then cold rolling and annealing are repeated to obtain a cold rolled material. Thereafter, intermediate recrystallization annealing and intermediate cold rolling are performed under the conditions shown in Table 1. The steps of final recrystallization annealing and finish cold rolling were sequentially performed to finish the metal mask materials having the product thicknesses of Examples 1 to 8 and Comparative Examples 1 to 4 in Table 1. Further, strain relief annealing was performed at 300 ° C. for 12 hours. In addition, a composition having Fe added with 31 mass% Ni and 5 mass% Co was manufactured as Example 9. The manufacturing process of Example 9 is the same as the other examples.
Note that the grain size number GSNO. Was set to 10.0. Moreover, the surface roughness of the rolling roll was adjusted for each Example so that the arithmetic average roughness Ra of the product surface was 0.07 to 0.08 (0.065 to 0.084).
The following evaluation was performed about the metal mask material of each Example after a strain relief annealing, and a comparative example.

(1) Arithmetic mean roughness Ra
Measured as described above. For the measurement, a contact type surface roughness meter (SE-3400 manufactured by Kosaka Laboratory) was used, and an average value measured with n ≧ 3 was obtained.
(2) 60 degree gloss G60
Measured as described above. The average value measured by n> = 3 was calculated using a handy gloss meter PG-1 manufactured by Nippon Denshoku Industries Co., Ltd.

(3) Presence or absence of erroneous measurement of surface defects For each metal mask material of each example and comparative example, five levels of surface defects were intentionally created, and the surface defects were measured with a CCD camera.
Specifically, a 50 mm × 50 mm acid-resistant tape was applied to the surface of each metal mask material, and an opening of 10 mm × 10 mm was provided at the center to partially expose the surface. An etching solution having the following five concentrations was applied to the exposed portion to form surface irregularities, thereby forming surface defects. Since this exposed part can be visually confirmed as being cloudy as compared with the surrounding area, it was regarded as a reference surface defect.
Etching solution is 47 baume ferric chloride aqueous solution as it is, 5 types diluted with water 2 times, 4 times, 8 times and 16 times respectively, and tweezers with absorbent cotton soaked with etching solution The exposed portion was rubbed with absorbent cotton for 15 seconds and etched. After etching, the etching solution was wiped off with a cloth soaked in water, and the acid-resistant tape was peeled off. In the case where the ferric chloride aqueous solution was used for etching without diluting, the metallic luster of the exposed portion was completely lost and white, and the fogging of the exposed portion became weaker as the dilution rate increased. In addition, when the dilution rate was 32 times, the fogging of the exposed portion could not be visually confirmed, so it was considered that no surface defects were formed, and those with a dilution rate of up to 16 times were used. Therefore, in the etching with the above five kinds of etching solutions, surface defects that can be visually confirmed are formed, and should not be affected by surface irregularities of the metal mask material, but should be detected as surface defects by the CCD. It is.
Next, pixel data of 256 gradations (± 128) was taken with a CCD camera for the five types of surface defects described above. Here, the state where the reflected light is blocked is the darkest reflection, and this is set to -128, and the reflection from the stationary part (part around the exposed part) is set to ± 0 on the surface of the metal mask material. . Then, a reflection that falls within the range of brightness ± 20 is defined as a normal reflection at the stationary part, and a reflection that deviates from the range of brightness ± 20 is defined as an abnormal reflection at the surface defect, and this abnormality is reflected at the exposed part. It was confirmed whether or not can be detected.
Regarding the metal mask materials of each of the examples and comparative examples, when all of the five types of surface defects described above were detected, it was determined that “there was no erroneous measurement of surface defects”, and one or more types of surface defects were selected from the five types. When it was not detected, it was determined that “the surface defect was erroneously measured”.

  As is apparent from Table 1, in the case of each Example in which Ra is 0.01 to 0.20 μm and G60 is 200 to 600, no erroneous measurement of surface defects occurred.

On the other hand, in the case of Comparative Example 1 in which the workability of finish cold rolling is less than 70% and Comparative Example 2 in which the rolling speed of finish cold rolling exceeds 60 m / min, G60 is less than 200, and surface defects are erroneously measured. Occurred.
In the case of Comparative Example 3 in which the final recrystallization annealing was performed under the condition that the crystal grain size (GSNo.) Of the final recrystallization annealing was less than 9.0, and the comparative example in which the workability of the intermediate cold rolling was less than 85% In the case of 4, G60 was less than 200, and the surface defect was erroneously measured.

Claims (2)

Containing 30 to 45% by mass of Ni and Co, 0 to 6% by mass of Co, and comprising a rolled foil of an Fe-Ni alloy composed of the balance Fe and inevitable impurities,
Thickness t is 0.02 to 0.08 mm,
An arithmetic average roughness Ra measured in accordance with JIS-B0601 in the rolling parallel direction and the perpendicular direction of rolling is 0.01 to 0.20 μm,
And the metal mask material whose 60 degree glossiness G60 measured according to JIS-Z8741 in the rolling parallel direction and the rolling right angle direction is 200-600.   A metal mask using the metal mask material according to claim 1.