JP7851764B2 - Plasma mask and plasma treatment method - Google Patents

Description

This invention relates to a plasma treatment process that modifies and removes at least one of the surface coating layers of an object to be treated.

A display device used to operate the navigation system, audio system, television receiver, etc., is installed in the vehicle.

Conventionally, in display devices mounted on vehicles, encoder components for volume control, etc., were located on the bezel (see, for example, Patent Document 1). In a display device with a bezel, as shown in the partial cross-sectional view in Figure 1, the encoder component 101 is connected to a circuit board 103, which is positioned opposite the bezel 102, by solder 104.

However, in recent years, the mainstream configuration for display devices mounted on vehicles has been one that incorporates a display panel that is an electrostatic touch panel and does not have a bezel. In a bezel-less display device, for example, as shown in the partial cross-sectional view in Figure 2, the encoder component 201 is fixed to the surface of the display panel 202, which includes the electrostatic touch panel 202B, by adhesive 203. Furthermore, a Flexible Printed Circuit (FPC), used to establish an electrical connection between the encoder component 201 and other components, is connected to the encoder component 201.

The display panel 202 includes, in addition to the electrostatic touch panel 202B, a liquid crystal layer 202A, an anti-reflective resin layer 202C, glass 202D, and a surface coating layer 202E. The surface of the glass 202D is chemically strengthened. An example of the surface coating layer 202E is a structure in which an AG (Anti-Glare) layer, an AR (Anti-Reflective) layer, and an AFP (Anti-Finger Print) layer are laminated in the order of AG layer, AR layer, and AFP layer from the side closest to the glass 202D.

Japanese Patent Publication No. 2019-202553

The surface of display panels, including electrostatic touch panels, is coated with a surface coating layer to prevent fingerprint adhesion. This surface coating layer is composed of components that do not adhere to adhesives. Therefore, the surface coating layer must be removed in areas where adhesives will be applied.

One possible method for removing the surface coating layer is to partially mask the surface of the display panel during the formation of the surface coating layer. However, adopting this method would significantly increase costs.

Therefore, from the perspective of cost reduction, it is desirable to adopt a method of modifying the surface coating layer of the area to be bonded with adhesive using plasma treatment before bonding.

In plasma processing, heat is generated when plasma is irradiated onto the object being processed. Therefore, prolonged exposure to plasma may damage the object.

For example, surface modification is possible with short-duration plasma irradiation for common materials such as ABS resin. However, when high energy is required for surface modification, such as for surface coating layers, prolonged plasma irradiation is necessary, making it impossible to avoid high temperatures on the material being treated. Therefore, to prevent damage to the material, it becomes necessary to perform plasma irradiation in multiple stages, allowing time for the material's temperature to cool down, which leads to a decrease in productivity.

In view of the above problems, the present invention aims to provide a plasma treatment mask and a plasma treatment method using the plasma treatment mask that enable at least one of modification and removal of a surface (e.g., the surface coating layer of the object to be treated) to an object to be treated without damaging the object and in a short time.

An exemplary plasma processing mask of the present invention comprises an opening corresponding to the plasma processing area of the object to be processed, and a flow path for circulating a cooling gas. The outlet of the flow path communicates with the opening.

According to an exemplary version of the present invention, it is possible to perform at least one of modification and removal on the surface of an object to be treated (e.g., the surface coating layer of the object to be treated) in a short time without damaging the object.

Partial cross-sectional view of a display device with a bezel Partial cross-sectional view of a display device without a bezel Top view of a plasma processing mask according to the first embodiment Cross-sectional view of a plasma processing mask according to the first embodiment. A flowchart illustrating the plasma processing method using a plasma processing mask according to the first embodiment. This figure shows the plasma processing mask according to the first embodiment installed on the object to be processed. This diagram shows the state in which plasma is being irradiated from the plasma head onto the plasma processing area of the object to be processed. Diagram showing the direction of movement of the plasma head. A diagram showing the state of the object being processed being air-cooled. This diagram shows the temperature characteristics of the object being processed with and without air cooling. This diagram shows the temperature characteristics of the object being processed with and without air cooling. This diagram shows the relationship between cooling time, cooling gas flow rate, and the temperature of the object being processed after air cooling. Top view of a plasma processing mask according to the second embodiment Cross-sectional view of a plasma processing mask according to the second embodiment.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings.

<First Embodiment>
Figure 3 is a top view of the plasma processing mask according to the first embodiment. Figure 4 is a cross-sectional view of the plasma processing mask according to the first embodiment when cut along the AA cross-section shown in Figure 3.

The plasma processing mask 1 of this embodiment comprises a first heat conductive member 2, a second heat conductive member 3, and a liner 4.

The materials of the first heat conduction member 2 and the second heat conduction member 3 are metals with high thermal conductivity, such as aluminum, aluminum alloys, copper, and copper alloys. This allows for efficient heat dissipation from the object being processed.

The liner 4 is made of a rubber-based resin material such as urethane or silicone, which has appropriate flexibility. This prevents damage to the object being processed due to contact with the plasma processing mask 1, and improves adhesion to the object, preventing plasma leakage. It is desirable that the rubber-based resin material used as the liner 4 contains a heat-conducting filler such as alumina. The presence of a heat-conducting filler allows for efficient transfer of heat from the object being processed to the second heat-conducting member 3 via the liner 4.

The plasma processing mask 1 has a structure in which a first heat conductive member 2, a second heat conductive member 3, and a liner 4 are stacked in the vertical direction. Furthermore, the plasma processing mask 1 is provided with an opening 5 corresponding to the plasma processing area of the object to be processed.

Since the opening 5 is assumed to be a cylindrical member to be processed, it has a C-shape when viewed from above. However, the shape of the opening 5 is not limited to a C-shape; it can be made into an appropriate shape according to the shape of the object to be processed.

Furthermore, by stacking the first heat conductive member 2 and the second heat conductive member 3 in the vertical direction, two flow channels 6 and 7 are formed in the plasma processing mask 1 by grooves provided in the first heat conductive member 2 and the second heat conductive member 3, respectively. That is, the plasma processing mask 1 includes flow channels 6 and 7. Flow channels 6 and 7 are for flowing a cooling gas. For example, air can be used as the cooling gas. However, the cooling gas may be a gas other than air.

Unlike this embodiment, it is possible to have only one flow path. However, by providing multiple flow paths as in this embodiment, it becomes possible to cool the entire object while suppressing the temperature distribution, even when the plasma processing area of the object is extensive. Note that when providing multiple flow paths, the number of flow paths is not limited to two; it may be three or more.

The outlet 61 of channel 6 and the outlet 71 of channel 7 are connected to the opening 5. This allows cooling gas to be introduced into the inlets 62 of channel 6 and 72 of channel 7, causing the cooling gas to be blown out of the opening 5. This cooling gas suppresses the temperature rise of the object being treated. Therefore, by using the plasma treatment mask 1, it is possible to modify and remove at least one of the surface coating layers of the object being treated in a short time without damaging it.

In the plasma processing mask 1, a stepped portion 63 is provided in the flow path 6, and a stepped portion 73 is provided in the flow path 7. The stepped portion 63 facilitates the positioning of the outlet 61 at a desired vertical position, and the stepped portion 73 also facilitates the positioning of the outlet 71 at a desired vertical position.

In the plasma processing mask 1, the vertical positions of the outlets 61 and 71 are positioned near the object being processed. This allows for efficient cooling of the object being processed by blowing cooling gas.

The second heat conduction member 3 includes a heat sink 8. That is, the plasma processing mask 1 includes a heat sink 8. The heat sink 8 releases the heat generated by the object being processed into the atmosphere. The heat sink 8 further suppresses the temperature rise of the object being processed.

In the plasma processing mask 1, a portion of the opening 5 is located between the outlet 61 and the heat sink 8, and another portion of the opening 5 is located between the outlet 71 and the heat sink 8. This arrangement allows the cooling gas to contribute not only to the cooling of the object being processed but also to the cooling of the heat sink 8. Therefore, efficient utilization of the cooling gas becomes possible.

Next, we will explain the plasma treatment method using the plasma treatment mask 1. Figure 5 is a flowchart illustrating the schematic of the plasma treatment method using the plasma treatment mask 1.

First, the operator places the plasma treatment mask 1 on the object to be treated 9 (step S1). Once the plasma treatment mask 1 is placed on the object to be treated 9, the plasma treatment mask 1 and the object to be treated 9 will be in the state shown in Figure 6. The object to be treated 9 is, for example, a display panel including a surface coating layer 9E. An example of a display panel including a surface coating layer 9E is a display panel in which a liquid crystal layer 9A, an electrostatic touch panel 9B, an anti-reflective resin layer 9C, glass 9D, and the surface coating layer 9E are laminated in that order. The surface of the glass 9D is chemically strengthened. An example of a surface coating layer 9E is a structure in which an AG layer, an AR layer, and an AFP layer are laminated in the order of AG layer, AR layer, and AFP layer from the side closest to the glass 9D.

In step S2, following step S1, plasma P2 is irradiated from the plasma head P1 onto the plasma processing area of the object to be processed 9, as shown in Figure 7. The plasma head P1 is provided in the plasma irradiation device. As with the plasma processing mask 1, by shaping the liner 4 so that its side surface is further away from the plasma processing area of the object to be processed 9 than the side surfaces of the first heat conductive member 2 and the second heat conductive member 3, the degree of alignment between the side surfaces of the first heat conductive member 2 and the second heat conductive member 3 and the outer edge of the plasma processing area of the object to be processed 9 can be increased. On the other hand, unlike the plasma processing mask 1, if the side surfaces of the first heat conductive member 2 and the second heat conductive member 3 and the side surface of the liner 4 are flush, the plasma will weaken near the side surfaces of the first heat conductive member 2 and the second heat conductive member 3, and the surface of the object to be processed 9 will neither be modified nor removed by the plasma.

Since the plasma outlet of the plasma head P1 is smaller than the plasma processing area c, the plasma head P1 is moved in the direction D1 along the arc of the opening 5, as shown in Figure 8.

In step S3, following step S2, the plasma irradiation device determines whether the number of plasma irradiations has reached the set value. If the number of plasma irradiations reaches the set value, the series of plasma processing steps ends.

On the other hand, if the number of plasma irradiations has not reached the set value, the process proceeds to step S4. As shown in Figure 9, the cooling gas introduced from inlet 62 moves along the flow direction D2 and is blown out from outlet 61, and the cooling gas introduced from inlet 72 moves along the flow direction D3 and is blown out from outlet 71. As a result, the object to be processed 9 is air-cooled by the cooling gas.

The cooling gas is introduced into inlets 62 and 72 at a set flow rate. Once the set cooling time has elapsed, the air cooling in step S4 is terminated, and the process returns to step S2.

For example, if the object to be processed 9 is a display panel with the configuration shown in Figure 2, plasma processing that ensures the desired adhesion can be achieved by setting the movement speed of the plasma head P1 to 50 mm/second and the number of plasma irradiations to four.

Figures 10A and 10B show the temperature characteristics T1 of the object 9 being processed with air cooling and T2 of the object 9 being processed without air cooling. Figure 10A shows an example where, when a series of plasma treatments are performed for the same processing time, the temperature of the object 9 rises excessively beyond the acceptable range when air cooling is absent. Figure 10B shows an example where, in order to prevent the temperature of the object 9 from exceeding the acceptable range, the series of plasma treatments takes too long when air cooling is absent. In the example shown in Figure 10B, the time required for the series of plasma treatments can be shortened when air cooling is present compared to when air cooling is absent.

The optimal number of plasma irradiations varies depending on the type of object 9 being treated. Therefore, in a plasma treatment method using the plasma treatment mask 1, it is desirable to change the number of plasma irradiations according to the object 9 being treated.

Furthermore, as shown in Figure 11, the peak temperature of the object being processed 9 changes depending on the supply time (cooling time) and the flow rate of the cooling gas. Therefore, in the plasma processing method using the plasma processing mask 1, it is desirable to change the supply time (cooling time) and the flow rate of the cooling gas according to the required processing time. Note that the required processing time may vary depending on, for example, the production situation.

<Second Embodiment>
Figure 12 is a top view of a plasma processing mask according to the second embodiment. Figure 13 is a cross-sectional view of the plasma processing mask according to the second embodiment when cut along the AA cross-section shown in Figure 12.

In the plasma processing mask 10 of this embodiment, the same reference numerals are used for parts identical to those in the plasma processing mask 1 of the first embodiment, and detailed descriptions are omitted.

The plasma processing mask 10 of this embodiment differs from the plasma processing mask 1 of the first embodiment in the shape of the flow channels 6 and 7 and the orientation of the fins of the heat sink 8.

In the plasma processing mask 10, a stepped portion 63 is provided in the flow path 6, and a stepped portion 73 is provided in the flow path 7. The stepped portion 63 facilitates the positioning of the outlet 61 at a desired vertical position, and the stepped portion 73 also facilitates the positioning of the outlet 71 at a desired vertical position.

In the plasma processing mask 10, the vertical positions of the outlets 61 and 71 are positioned opposite the grooves formed between the fins of the heat sink 8. This improves the heat dissipation capacity of the heat sink 8 through the blowing of cooling gas.

Furthermore, in the plasma processing mask 10, the multiple fins of the heat sink 8 extend along the direction of the cooling gas outflow from the outlets 61 and 71. This allows the cooling gas to easily enter the grooves formed between the fins of the heat sink 8, further improving the heat dissipation capacity of the heat sink 8.

The plasma treatment method using the plasma treatment mask 10 is the same as the plasma treatment method using the plasma treatment mask 1, therefore, the explanation is omitted.

<Notes>
The various technical features disclosed in the embodiments for carrying out the invention as described herein can be modified in various ways without departing from the spirit of the technical creation. Furthermore, the multiple embodiments and modifications disclosed in the embodiments for carrying out the invention as described herein may be combined to the extent possible.

1, 10 Plasma processing mask 2 First heat conductive member 3 Second heat conductive member 4 Liner 5 Opening 6, 7 Flow channels 61, 71 Outlet 62, 72 Inlet 63, 73 Stepped section 8 Heat sink 9 Object to be processed 9A Liquid crystal layer 9B Electrostatic touch panel 9C Anti-reflective resin layer 9D Glass 9E Surface coating layer P1 Plasma head P2 Plasma

Claims (9)

An opening corresponding to the plasma processing area of the object to be processed,
It is equipped with a flow path for circulating cooling gas,
The object to be processed is a display panel including a surface coating layer.
The outlet of the flow path is a plasma processing mask that communicates with the opening. An opening corresponding to the plasma processing area of the object to be processed,
It is equipped with a flow path for circulating cooling gas,
A stepped portion is provided in the aforementioned flow path.
The outlet of the flow path is a plasma processing mask that communicates with the opening. An opening corresponding to the plasma processing area of the object to be processed,
A passage for flowing cooling gas,
Equipped with a heatsink ,
The outlet of the flow path is a plasma processing mask that communicates with the opening. The plasma processing mask according to claim 3 , wherein at least a portion of the opening is located between the outlet and the heat sink. The heat sink is equipped with multiple fins,
The plasma processing mask according to claim 4 , wherein the plurality of fins extend along the direction of outflow of the cooling gas from the outlet. A plasma processing mask according to any one of claims 1 to 5 , comprising a plurality of the aforementioned flow channels. A step of placing the plasma processing mask described in any one of claims 1 to 6 on the object to be processed,
The process of irradiating the plasma processing area with plasma,
A plasma treatment method comprising the following features. The plasma treatment method according to claim 7 , wherein the number of plasma irradiations is changed according to the object to be treated. The plasma processing method according to claim 7 or claim 8 , wherein the supply time and flow rate of the cooling gas supplied to the flow path are changed according to the required processing time.