TWI867889B - Metal mask and evaluation method thereof - Google Patents

Abstract

A metal mask includes a substrate. The substrate has a plurality of through holes, A plurality of star-shaped areas formed between the through holes, an outline of each the star-shaped area has a plurality of tips and a plurality of arcs. Each of the arcs is located between two adjacent of the tips. In each of the star-shaped areas, a polygonal block is surrounded by a plurality of tangent lines of tops of the arcs surround. Each of the polygonal blocks has a surface area. Wherein a value N1 is a difference between a maximum value of the surface areas and a minimum value of the surface areas divided. A value N2 is a sum of the maximum value and the minimum value. N1/N2 is less than 60%. An evaluation method for a metal mask is also provided.

Description

Metal mask and metal mask evaluation method

The present invention relates to a metal mask, in particular to a metal mask used in manufacturing a display panel and a method for evaluating the metal mask.

Display panels using organic light-emitting diodes (OLED) are currently common electronic device display components. This type of display panel has many advantages such as self-luminescence, wide viewing angle, high energy efficiency, fast response time and thinness, and is popular among consumers.

The common manufacturing method of organic light-emitting diode display panels is to first make multiple sub-masks with through holes, and then spread the multiple sub-masks into a fine metal mask (FMM), and then use evaporation to deposit the organic light-emitting material through the metal mask on the glass substrate to form a light-emitting pattern. Since the metal mask may be deformed after the spread, the position of the through hole will be offset, and the position offset of the through hole will affect the distribution of the light-emitting pattern on the glass substrate and affect the display quality of the organic light-emitting diode display panel. Therefore, in practice, it is hoped that the metal mask has sufficient structural strength to suppress the position offset of the through hole.

The present invention provides a metal mask that still has a good shape after being stretched, which can improve the manufacturing yield.

The present invention also provides a method for evaluating a metal mask, and the evaluated metal mask still has a good shape after being stretched, thereby improving the manufacturing yield.

To achieve the above advantages, an embodiment of the present invention provides a metal mask, including: a substrate. The substrate has a plurality of through holes, and a plurality of star-shaped areas are formed between the through holes, and the outline of each star-shaped area has a plurality of tips and a plurality of arc-shaped parts, and each arc-shaped part is located between two adjacent tips. In each star-shaped area, the tangent of the top of the arc-shaped part surrounds a polygonal block, and each polygonal block has a surface area, and the difference between the maximum value and the minimum value in the surface area is N1, and the sum of the maximum value and the minimum value is N2, and N1/N2 is less than 60%.

In one embodiment, the through hole has an arc-shaped wall along the thickness direction of the substrate.

In one embodiment, the above-mentioned through holes are arranged in an equidistant array.

In one embodiment, the star-shaped region is located on the evaporation surface of the substrate on one side close to the evaporation source.

In one embodiment, the number of through holes surrounding each of the above-mentioned star-shaped areas is 4, and the outline of the polygonal block is a quadrilateral.

In one embodiment, the polygonal block has two first edges extending along a first direction and parallel to each other and two second edges extending along a second direction and parallel to each other.

In one embodiment, the first direction is perpendicular to the second direction.

In one embodiment, the first edge group has a first shortest distance, the second edge group has a second shortest distance, and the surface area is the product of the first shortest distance and the second shortest distance.

A method for evaluating a metal mask, wherein the metal mask has a substrate, the substrate has a pattern area, the pattern area has a plurality of through holes and a plurality of star-shaped areas, each star-shaped area is surrounded by a plurality of adjacent through holes, and the outline of each star-shaped area has a plurality of tip portions and a plurality of arc portions corresponding to the number of through holes surrounding the star-shaped area, each arc portion is between every two adjacent tip portions, and the evaluation method includes ：Divide the polygonal blocks in the star-shaped area. The polygonal blocks have multiple edges. The number of edges corresponds to the number of arcs, and each edge is inscribed in an arc. Calculate the multiple surface areas of the polygonal blocks in the pattern area. When the difference between the maximum and minimum values in the surface area is N1, the sum of the maximum and minimum values is N2, and the value of N1/N2 is less than the expected value, the metal mask is evaluated as qualified.

Based on the above description, the metal mask of the present invention has a good structural shape, so that the position of the through hole is not easy to produce too much deviation after the mesh is stretched, thereby improving the manufacturing yield. And the evaluation method of the present invention, because the metal mask that has passed the evaluation has a structural shape that meets the above metal mask, the metal mask that has passed the evaluation is used in the process of producing display panels, which can improve the manufacturing yield.

In order to make the above and other purposes, features and advantages of the present invention more clearly understood, the following is a detailed description of the embodiments with the help of the attached drawings.

100: Metal mask

1: Substrate

11: Pattern area

11a: Pattern area

12: Clamping area

13: Fixed area

2: Through hole

2a: First opening

2b: Second opening

2c: Neck opening

23: Arc-shaped wall

24: Empty

21: Star area

211: Tip

212: arc-shaped part

4: Polygonal block

3c, 3d: First edge

3a, 3b: Second edge

L1: The second shortest distance

L2: First shortest distance

S1: Steamed noodles

S2: Back

D1: First direction

D2: Second direction

D3, D4: Arrangement direction

T: thickness direction

S110: Step

S120: Step

S130: Step

A-A: Section line

FIG1 is a three-dimensional schematic diagram of a metal mask of an embodiment of the present invention; FIG2 is a schematic diagram of a pattern area in the embodiment of FIG1; FIG3 is a schematic diagram of a star-shaped area in the embodiment of FIG1; FIG4 is a three-dimensional schematic diagram of a pattern area in the embodiment of FIG1; FIG5 is a schematic diagram of the A-A section in FIG2; FIG6 is a schematic diagram of the relationship between the maximum offset of the through hole in the X direction and the divergence; FIG7 is a schematic diagram of a pattern area of a test example of the embodiment of FIG1; FIG8 is a three-dimensional schematic diagram of the test example of FIG7; FIG9 is a flow chart of the evaluation method of the present invention.

In the following article, the terms used in the description of the embodiments of the present invention, such as "upper", "lower", etc., indicating the orientation or position relationship, are described according to the orientation or position relationship shown in the drawings used. The above terms are only for the convenience of describing the present invention and are not intended to limit the present invention, that is, they do not indicate or imply that the components mentioned must have a specific orientation or be constructed in a specific orientation. In addition, the terms "first", "second", etc. mentioned in this specification or the scope of the patent application are only used to name the element or distinguish different embodiments or scopes, and are not used to limit the upper or lower limit of the number of elements.

FIG1 is a three-dimensional schematic diagram of a metal mask of an embodiment of the present invention. FIG2 is a schematic diagram of a pattern area in the embodiment of FIG1. FIG3 is a schematic diagram of an island area in the embodiment of FIG1. As shown in FIG1 to FIG3, the metal mask 100 of the present invention, in one embodiment, comprises: a substrate 1. The substrate 1 has a plurality of through holes 2, and a plurality of star-shaped areas 21 are formed between these through holes 2, and the outline of each star-shaped area 21 has a plurality of tip portions 211 and a plurality of arc portions 212, and each arc portion 212 is located between two adjacent tip portions 211. In each star-shaped area 21, the tangent of the top of the arc-shaped portion 212 surrounds a polygonal block 4, each of which has a surface area, the difference between the maximum and minimum values in these surface areas is N1, the sum of the maximum and minimum values is N2, and the value of N1/N2 (for the convenience of subsequent explanation, this value is referred to as the divergence below) is less than 60%.

Specifically, as shown in FIG. 1 , in this embodiment, the substrate 1 is, for example, a rectangular plate. Specifically, the length of the substrate 1 is, for example, between 150 and 500 mm, and the thickness is, for example, between 10 and 150 μm, but not limited thereto. The material of the substrate 1 is, for example, a nickel-iron alloy, but not limited thereto. The surface of the substrate 1 is divided into a deposition surface S1 and a back surface S2 along the thickness direction T (see FIG. 5 ). The deposition surface S1 is the surface facing the deposition source (not shown) when in use. The back surface S2 is the surface facing the glass substrate (not shown) when in use.

As shown in FIG. 1 , in this embodiment, in addition to the pattern area 11 located in the center of the substrate 1, the substrate 1 also includes, for example, clamping areas 12 located at both ends in the long axis direction of the substrate 1 and a fixing area 13 located between the clamping area 12 and the pattern area 11. The clamping area 12 is an area for the clamp (not shown) to temporarily clamp the substrate 1 when the substrate 1 is connected to the outer frame (not shown). The fixing area 13 is an area that contacts the outer frame and is fixed when the substrate 1 is connected to the outer frame (not shown) for stretching. However, the detailed form of the substrate 1 is not limited to the above examples.

FIG4 is a three-dimensional schematic diagram of the pattern area in the embodiment of FIG1. FIG5 is a schematic diagram of the A-A section in FIG2. The pattern area 11 is an area used to cover the glass substrate (not shown) during the evaporation process to form a luminous pattern (not shown). As shown in FIG1, FIG2 and FIG4, in this embodiment, the pattern area 11 includes, for example but not limited to, 6 pattern areas 11a spaced apart from each other, and each pattern area 11a is provided with a plurality of through holes 2 penetrating the substrate 1 in the thickness direction T of the substrate 1. As shown in FIG5, each through hole 2 includes, for example, a first opening 2a located on the evaporation surface S1, a second opening 2b located on the back surface S2, and a neck opening 2c located between the first opening 2a and the second opening 2b. The opening size of the neck opening 2c is, for example, smaller than the size of the first opening 2a and also smaller than the size of the second opening 2b. The through hole 2 is formed, for example, by wet etching. The wall surface between the first opening 2a and the neck opening 2c and the wall surface between the second opening 2b and the neck opening 2c are, for example, arc-shaped wall surfaces 23 (see FIG. 4 or FIG. 5).

As shown in FIG. 2 and FIG. 4 , along the thickness direction T (the direction perpendicular to the evaporation surface S1), in this embodiment, the neck opening 2c has different lengths in the first direction D1 and the second direction D2 perpendicular to the thickness direction T, respectively, and presents a rectangle extending toward the first direction D1 or the second direction D2, but the present invention is not limited thereto. In this embodiment, the first direction D1 and the second direction D2 are perpendicular to each other, for example, and the arrangement direction between the first direction D1 and the through hole 2 (or the star-shaped area 21) (arrangement direction D3 and arrangement direction D4 in FIG. 2 ) is, for example, 45 degrees, but the present invention is not limited thereto.

As shown in FIG. 2 and FIG. 3, in this embodiment, these through holes 2 are arranged in an array with equal spacing, and are close to each other so that the through holes 2 viewed on the evaporation surface S1 have a common opening edge. These through holes 2, for example, form a pattern area 11a in a manner in which four through holes 2 surround a star-shaped area 21. The shape of the polygonal block 4 in the star-shaped area 21 corresponds to the number of through holes 2 around it and presents a quadrilateral, but the number of through holes 2 surrounding each star-shaped area 21 is not limited to this. In other words, in the embodiment not shown in the figure, the polygonal block 4 can be a rhombus, a triangle or other polygons depending on the distribution pattern and number of the through holes 2.

It should be understood that since the through hole 2 penetrates the substrate 1, the shape of the remaining star-shaped area 21 and the relative size relationship between the star-shaped areas 21 will affect the structure of the metal mask 100, and then affect the stress or gravity generated by the net after the net is stretched, which affects the position offset of each through hole 2. When evaluating the position offset of the through hole 2 after the metal mask 100 is stretched, the dispersion of the star-shaped area 21 can be calculated. If the dispersion is smaller, it means that the shape and size of each star-shaped area 21 in the pattern area 11 are closer, and the structure of the metal mask 100 is more uniform, it is not easy to have a phenomenon of excessive position offset of the through hole 2 after the net is stretched.

As shown in FIG. 3 , in this embodiment, the quadrilateral polygonal block 4 has a first edge 3c and a first edge 3d extending along a first direction D1 and parallel to each other, and a second edge 3a and a second edge 3b extending along a second direction D2 and parallel to each other. The first edge 3c and the first edge 3d have a first shortest distance L2 between them. The second edge 3a and the second edge 3b have a second shortest distance L1 between them. Since the first direction D1 and the second direction D2 are perpendicular to each other in this embodiment, in this embodiment, the surface area is the product of the first shortest distance L2 and the second shortest distance L1. It should be understood that the above calculation method is only an example. In different embodiments, the method of calculating the surface area of the polygonal block 4 will be different depending on the shape of the polygonal block 4.

FIG6 is a schematic diagram showing the relationship between the maximum offset of the through hole in the X direction and the discreteness. The maximum offset (XPPA-MAX) in the X direction shown in FIG6 refers to the maximum value of the offset of each position of these through holes 2 in the plane perpendicular to the thickness direction T (evaporation surface S1, back surface S2) in the pattern area 11. The X direction in FIG6 refers to the direction along the long axis of the metal mask 100. As can be seen from FIG6, the maximum offset value is related to the discreteness of the surface area of these polygonal blocks 4. The higher the discreteness, the greater the maximum offset. In the embodiment of the present invention, since the maximum offset value of the through hole 2 of the metal mask 100 is expected to be less than 4μm after the net is stretched, it can be seen from FIG6 that the discreteness is expected to be less than 60%.

In addition, it should be understood that because the total length of the metal mask 100 in the short axis direction (perpendicular to the long axis direction) is shorter than the total length of the metal mask 100 in the long axis direction, when the through hole 2 is offset after the net is stretched, the offset (YPPA-MAX) of the through hole 2 in the short axis direction (Y direction) will be less than the maximum offset (XPPA-MAX) in the X direction. Therefore, when judging whether the metal mask 100 meets expectations, the maximum offset (XPPA-MAX) of the through hole 2 in the X direction can be used as a judgment basis, but it is not limited to this.

As can be seen from FIG3, when calculating the surface area of the star-shaped area 21 in the embodiment of this case, the tip 211 is avoided and only the polygonal block 4 is calculated. To illustrate the advantages of such a calculation method, please refer to FIG7 and FIG8. FIG7 is a schematic diagram of the pattern area of the test example of the embodiment of FIG1. FIG8 is a three-dimensional schematic diagram of the test example of FIG7. In the test example of FIG7, the divergence is, for example, greater than 60%, so that the star-shaped areas 21 at different positions have a large difference in surface area.

As described above, the through holes 2 are made by wet etching. Since the wet etching method has the characteristic of isotropic etching, there may be overlap between adjacent through holes 2 during etching, making the thickness (dimension along the thickness direction T) of the through holes 2 at the overlap thinner, and even generating a cavity 24 or a depression on the arc-shaped wall surface 23. As can be seen from FIG7 and FIG8, when the divergence between the star-shaped regions 21 is large, this phenomenon may form a cavity 24 below the tip 211 of some of the star-shaped regions 21 in the thickness direction T. Although such a cavity 24 will affect the structural strength of the substrate 1, it is difficult to be observed in the observation direction of FIG7 because it is blocked by the tip 211. Therefore, in the embodiment of FIG1, when the dispersion of the surface area of the star-shaped region 21 is used to evaluate the positional offset of the through hole 2 after the net is stretched, the tip 211 is avoided.

As shown in FIG9. The present invention also provides a method for evaluating a metal mask 100, wherein the metal mask 100 has a substrate 1 (in conjunction with FIG1), the substrate 1 has a pattern area 11, the pattern area 11 has a plurality of through holes 2 and a plurality of star-shaped areas 21 (in conjunction with FIG2), each star-shaped area 21 is surrounded by a plurality of adjacent through holes 2, and the outline of each star-shaped area 21 has a plurality of tip portions 211 and a plurality of arc portions 212 corresponding to the number of through holes 2 surrounding the star-shaped area 21, and each arc portion 212 is located between every two adjacent tip portions 211, and the evaluation method comprises: Step S110 (in conjunction with FIG3): Divide the star-shaped area 21 into A polygonal block 4, the polygonal block 4 has a plurality of edges (see the first edge 3c, the first edge 3d, the second edge 3a and the second edge 3b in FIG. 3), the number of edges corresponds to the number of arc-shaped portions 212, and each edge is inscribed in an arc-shaped portion 212; step S120 (in conjunction with FIG. 2 and FIG. 3): calculate the plurality of surface areas of the polygonal block 4 in the pattern area 11; step S130 (in conjunction with FIG. 6): when the difference between the maximum value and the minimum value of these surface areas is N1, the sum of the maximum value and the minimum value is N2, and N1/N2 (i.e., the aforementioned dispersion) is less than the expected value, the metal mask 100 is evaluated as qualified. The expected value is, for example, 60%, but is not limited thereto.

As described above, the metal mask of the present invention has a good structural shape, so that the position of the through hole is not easy to produce too much deviation after the mesh is stretched, thereby improving the production yield. And the evaluation method of the present invention, because the metal mask that has passed the evaluation has a structural shape that meets the above-mentioned metal mask, the metal mask that has passed the evaluation is used in the process of producing display panels, which can improve the production yield.

Although the present invention has been disclosed as above by way of embodiments, it is not intended to limit the present invention. Those with ordinary knowledge in the technical field to which the present invention belongs may make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of the patent application attached hereto.

21: Star area

211: Tip

212: arc-shaped part

4: Polygonal block

3c, 3d: First edge

3a, 3b: Second edge

L1: The second shortest distance

L2: First shortest distance

D1: First direction

D2: Second direction

D3, D4: Arrangement direction

Claims (9)

A metal mask, comprising: A substrate, having a plurality of through holes, wherein a plurality of star-shaped regions are formed between the through holes, and the contour of each of the star-shaped regions has a plurality of tips and a plurality of arc-shaped portions, and each of the arc-shaped portions is located between two adjacent tip-shaped portions; In each of the star-shaped regions, the tangents of the tops of the arc-shaped portions surround a polygonal block, and each of the polygonal blocks has a surface area, and a difference between a maximum value and a minimum value in the surface areas is N1, and a sum of the maximum value and the minimum value is N2, and N1/N2 is less than 60%. A metal mask as described in claim 1, wherein the through holes have arc-shaped walls along a thickness direction of the substrate. A metal mask as described in claim 1, wherein the through holes are arranged in an array with equal spacing. A metal mask as described in claim 1, wherein the star-shaped area is located on an evaporation surface on a side of the substrate close to an evaporation source. A metal mask as described in claim 1, wherein the number of through holes surrounding each of the star-shaped areas is 4, and the outline of the polygonal block is a quadrilateral. A metal mask as described in claim 5, wherein the polygonal block has two first edges extending along a first direction and parallel to each other and two second edges extending along a second direction and parallel to each other. A metal mask as described in claim 6, wherein the first direction is perpendicular to the second direction. A metal mask as described in claim 7, wherein the first edge group has a first shortest distance, the second edge group has a second shortest distance, and the surface area is the product of the first shortest distance and the second shortest distance. A method for evaluating a metal mask, the metal mask having a substrate, the substrate having a pattern area, the pattern area having a plurality of through holes and a plurality of star-shaped areas, each star-shaped area being surrounded by a plurality of adjacent through holes, and the outline of each star-shaped area having a plurality of tips and a plurality of arc-shaped parts corresponding to the number of the through holes surrounding the star-shaped area, each arc-shaped part being located between every two adjacent tips, the evaluation method comprising: Dividing a polygonal block in the star-shaped area, the polygonal block having a plurality of edges, the number of the edges corresponding to the number of the arc-shaped parts, and each edge being inscribed in one of the arc-shaped parts; Calculating a plurality of surface areas of the polygonal blocks in the pattern area; When the difference between a maximum value and a minimum value in the surface areas is N1, the sum of the maximum value and the minimum value is N2, and N1/N2 is less than an expected value, the metal mask is evaluated to be qualified.