Display device

Abstract

The present disclosure relates to a display device, the display device comprising: a display panel including a display surface and a rear surface opposite to each other; and a flexible printed circuit board that can be attached to the display panel at the rear surface of the display panel. The flexible printed circuit board includes a conductive layer, a passivation layer for defining an outer surface of the flexible printed circuit board, and a base film between the conductive layer and the passivation layer. The outer surface includes: a first region of the passivation layer where the rear surface of the display panel can be attached to the flexible printed circuit board; and a second region of the passivation layer where the rear surface of the display panel is not attached to the flexible printed circuit board, and the first region has a larger surface roughness than the second region.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims priority and all benefits arising therefrom to Korean Patent Application No. 10-2019-0027095, filed on Mar. 8, 2019, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure relates to a display device. Background Art

[0004] With the development of multimedia, display devices have become increasingly important. A typical display device, such as a liquid crystal display (“LCD”) device or an organic light emitting diode (“OLED”) display device, may include a display panel in which pixels for implementing a display of an image are defined and a printed circuit board (“PCB”) that provides signals for driving the display panel.

[0005] Due to the automation of the display device module process, an adhesive layer and a release layer may be temporarily attached to various components such as a PCB in the process of manufacturing a display device, and then, once the assembly of the display device is completed, the adhesive layer and the release layer may be removed together. Summary of the Invention

[0006] Embodiments of the present disclosure provide a display device that can have improved resistance to defects that may occur in relation to process automation.

[0007] However, embodiments of the present disclosure are not limited to the embodiments set forth herein. The above and other embodiments of the present disclosure will become more apparent to those of ordinary skill in the art to which the present disclosure pertains by referring to the detailed description of the present disclosure given below.

[0008] According to an embodiment of the present disclosure, a display device includes: a display panel including a display surface and a rear surface opposite the display surface; and a flexible printed circuit board attachable to the display panel at the rear surface of the display panel. The flexible printed circuit board includes a conductive layer, a passivation layer defining an outer surface of the flexible printed circuit board, and a base film between the conductive layer and the passivation layer, and the outer surface includes: a first region of the passivation layer where the rear surface of the display panel is attachable to the flexible printed circuit board; and a second region of the passivation layer where the rear surface of the display panel is not attached to the flexible printed circuit board, and the first region has a larger surface roughness than the second region.

[0009] According to an embodiment of the present disclosure, the display device further includes: a first adhesive that can adhere to the display panel and can adhere to the passivation layer at the first region of the passivation layer.

[0010] According to an embodiment of the present disclosure, the overlapping area of the first adhesive with the first region of the passivation layer is greater than the overlapping area of the first adhesive with the second region of the passivation layer.

[0011] According to an embodiment of the present disclosure, within the flexible printed circuit board, the passivation layer includes a resin layer and fillers dispersed in the resin layer.

[0012] According to an embodiment of the present disclosure, at the first region of the passivation layer, the fillers protrude from the resin layer to be exposed to the outside of the resin layer.

[0013] According to an embodiment of the present disclosure, the adhesion of the first adhesive at the first region of the passivation layer sets the first adhesive to contact both the resin layer and the fillers exposed to the outside of the resin layer.

[0014] According to an embodiment of the present disclosure, the first adhesive includes: a first adhesive layer where the first adhesive can adhere to the passivation layer at the first region of the passivation layer; a second adhesive layer where the first adhesive can adhere to the display panel; and a first matrix layer between the first adhesive layer and the second adhesive layer, and the adhesion strength of the first adhesive layer is greater than the adhesion strength of the second adhesive layer.

[0015] According to an embodiment of the present disclosure, the average thickness of the passivation layer at the first region of the passivation layer is less than the average thickness of the passivation layer at the second region of the passivation layer.

[0016] According to an embodiment of the present disclosure, the first region of the passivation layer is a plasma etching region of the passivation layer.

[0017] According to an embodiment of the present disclosure, at the first region, the passivation layer defines a recess that is recessed from the outer surface at the second region, the recess is defined by a bottom surface and side surfaces connecting the bottom surface and the outer surface at the second region, and the surface roughness of the passivation layer at the bottom surface of the recess is greater than the surface roughness of the side surfaces of the recess.

[0018] According to one or more embodiments of the present disclosure, it is possible to facilitate the removal of an adhesive used for temporarily attaching an element used in an automated process and then removed after assembly. At the same time, the bonding strength of the adhesive used for bonding such a temporary element can be improved. Therefore, defects that may occur during the removal of the release layer from the adhesive can be reduced or effectively prevented, and process automation can be achieved.

[0019] Other features and embodiments will be apparent from the following detailed description, the drawings, and the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and other embodiments and features of the present disclosure will become more apparent by referring to the embodiments of the present disclosure described in detail with reference to the drawings, in which:

[0021] Figure 1 is a perspective view of an embodiment of a display device;

[0022] Figure 2 is Figure 1 an exploded perspective view of the display device;

[0023] Figure 3 is a diagram showing Figure 2 an enlarged cross-sectional view of an embodiment of a display area of a display panel in the display device;

[0024] Figure 4 is a diagram showing attached to Figure 2 in the display device Figure 2 a bottom plan view of an embodiment of a display panel;

[0025] Figure 5 is an enlarged cross-sectional view taken along line I-I' of Figure 4 ;

[0026] Figure 6 is a diagram showing Figure 2 a plan view of an embodiment of a display circuit board;

[0027] Figure 7 is an enlarged cross-sectional view taken along line II-II' of Figure 6 ;

[0028] Figure 8 is an enlarged cross-sectional view of another embodiment of a display circuit board;

[0029] Figure 9 is a flowchart showing an embodiment of a method for manufacturing a display circuit board; and

[0030] Figures 10 to 17 is a cross-sectional view showing an embodiment of respective structures in a process of a method for manufacturing a display circuit board. DETAILED DESCRIPTION

[0031] The features of the present disclosure and the methods of implementing the features of the present disclosure can be more easily understood by referring to the following detailed description of the embodiments and the accompanying drawings. However, the present disclosure may be implemented in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the present disclosure to those skilled in the art. Throughout the specification, the same reference numerals indicate the same elements.

[0032] It will be understood that when an element or layer is referred to as being "associated with" another element, such as "on" another element or layer, "connected to" or "coupled to" another element or layer, the element or layer can be directly on, directly connected to or directly coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly connected to" or "directly coupled to" another element or layer, there may be no intervening elements or layers. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0033] For ease of description, spatially relative terms such as "under", "below", "beneath", "above" and "on" may be used herein to describe the relationship of one element or feature to another element(s) or feature(s) as shown in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, an element described as "under" or "beneath" another element or feature will then be oriented "above" the other element or feature. Thus, the exemplary term "under" can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0034] It will be understood that although the terms first, second, etc. may be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below may be referred to as a second element, component, region, layer or section without departing from the teachings of the present disclosure.

[0035] The terms used herein are for the purpose of describing particular embodiments only and are not intended to be limiting. As used herein, unless the context clearly dictates otherwise, the singular forms "a", "an" and "the" are intended to include the plural forms, which include "at least one". "At least one" is not to be construed as limiting "a" or "an". "Or" means "and / or". As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. It will be further understood that when the terms "comprises" and / or "comprising" or "includes" and / or "including" or "contains" and / or "having" are used in this specification, it indicates the presence of the stated features, regions, wholes, steps, operations, elements and / or components, but does not preclude the presence or addition of one or more other features, regions, wholes, steps, operations, elements, components and / or groups thereof.

[0036] Taking into account the measurements under discussion and the errors associated with the measurement of a particular quantity (i.e., the limitations of the measurement system), "about" or "substantially" as used herein includes the stated value and means within an acceptable deviation range of a particular value determined by a person of ordinary skill in the art. For example, "about" can mean within one or more standard deviations, or within ±30%, ±20%, ±10% or ±5% of the stated value.

[0037] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by a person of ordinary skill in the art to which this disclosure pertains. It will be further understood that terms, such as those defined in a general dictionary, should be interpreted as having a meaning consistent with their meaning in the relevant art and the context of this disclosure, and will not be interpreted in an idealized or overly formal sense.

[0038] Embodiments are described herein with reference to cross-sectional views that are schematic illustrations of idealized embodiments. As such, variations in the shape of the illustrations due to, for example, manufacturing techniques and / or tolerances are to be expected. Accordingly, the embodiments described herein should not be construed as limited to the particular shapes of regions shown herein, but include deviations in shapes due to, for example, manufacturing. For example, regions shown or described as flat may generally have rough and / or non-linear features. Additionally, sharp corners shown may be rounded. Thus, the regions shown in the figures are substantially schematic in nature, and their shapes are not intended to show the exact shape of a region nor are they intended to limit the scope of the disclosure.

[0039] Embodiments of the present disclosure will be described hereinafter with reference to the accompanying drawings.

[0040] Figure 1 is a perspective view of an embodiment of a display device. Figure 2Yes Figure 1 Exploded perspective view of the display device Figure 3 Is a diagram showing Figure 2 An enlarged cross-sectional view of an embodiment of the display area of the display panel in the display device Figure 4 Is a diagram showing attached to Figure 2 In the display device of Figure 2 A bottom plan view of an embodiment of the cover window and the display panel Figure 5 Is an enlarged cross-sectional view taken along line I-I' of Figure 4 Of

[0041] Referring to Figures 1 to 5 The display device 1 may have a rectangular shape in a plan view. As shown in Figure 1 And Figure 2 For example, the display device 1 may have a rectangular shape in a plan view, the rectangular shape including a pair of relatively short sides extending along a first direction (or X-axis direction, for example, Figures 1 to 5 X in Figures 1 to 5 Y in Figures 1 to 5 Z in

[0042] The display device 1 may include a flat first region DR1 and a plurality of second regions DR2 (for example, a plurality of second regions DR2) respectively extending from opposite sides of the first region DR1. The second regions DR2 may be provided or formed as flat or curved (for example, bendable). When the second regions DR2 are provided or formed as flat, the angle formed by the first region DR1 and the second regions DR2 with respect to each other may be an obtuse angle. When the second regions DR2 are provided or formed as curved, the second regions DR2 may have a uniform or varying curvature.

[0043] Figure 1The second region DR2 is shown as extending from the left and right sides of the first region DR1, but the present disclosure is not limited thereto. Alternatively, the second region DR2 may extend from only one of the left and right sides of the first region DR1. Still alternatively, the second region DR2 may extend not only from the left and right sides of the first region DR1 corresponding to the relatively long sides of the display device 1, but also from at least one of the upper and lower sides of the first region DR1 corresponding to the relatively short sides of the display device 1. As an example, the second region DR2 will be described below as being provided on both the left and right sides of the display device 1.

[0044] The cover window 10 may be disposed above the display panel 20 (e.g., closer to the viewing side of the display device 1 than the display panel 20) to cover the top surface of the display panel 20. The cover window 10 may form the top located outside the display device 1. Thus, the cover window 10 may protect the top surface of the display panel 20. The cover window 10 may be attached to the top surface of the display panel 20 via an adhesive member. The cover window 10 may include glass, sapphire, and / or plastic, or may be formed of glass, sapphire, and / or plastic. The cover window 10 may be provided or formed as rigid or flexible. The adhesive member may be an optically clear adhesive (“OCA”) or an optically clear resin (“OCR”).

[0045] The cover window 10 may include a light-transmitting portion DA10 corresponding to the display panel 20 and a light-shielding portion NDA10 corresponding to the entire display device 1 except for the display panel 20. The cover window 10 may be disposed in the first region DR1 and the second region DR2 of the display device 1. The light-transmitting portion DA10 may be disposed in a part of the first region DR1 and may also be disposed in a part of the second region DR2.

[0046] The light-shielding portion NDA10 may be provided or formed as opaque. Alternatively, the light-shielding portion NDA10 may be provided or formed as a decorative layer having a pattern that can be observed from the outside of the display device 1 when an image is not displayed therethrough. In an example, for instance, a company logo or a string of various characters may be patterned on the light-shielding portion NDA10 as the above-described decorative layer.

[0047] The display panel 20 may be disposed below the cover window 10. The display panel 20 may be disposed to overlap with the light-transmitting portion DA10 of the cover window 10. The display panel 20 may be disposed in the first region DR1 and the second region DR2 of the display device 1. Thus, an image from the display panel 20 can be observed not only in the first region DR1 but also in the second region DR2.

[0048] As Figure 5As shown in the figure, the polarizing film PF can be disposed between the display panel 20 and the cover window 10 to reduce or effectively prevent visibility degradation that may be caused by the reflection of external light incident on the display device 1 from outside the display device 1. The polarizing film PF may include a polarizer and a phase retardation film such as a λ / 4 (or quarter-wave) plate. In this case, the phase retardation film may be disposed on the display panel 20, and the linear polarizer may be disposed between the phase retardation film and the cover window 10.

[0049] The display panel 20 may be a light-emitting diode (“LED”) display panel including LEDs. In an embodiment, for example, the display panel 20 may be an organic light-emitting diode (“OLED”) display panel using OLEDs (e.g., an OLED display panel), a micro light-emitting diode (“mLED”) display panel using mLEDs, or a quantum dot light-emitting diode (“QLED”) display panel using QLEDs. Hereinafter, the display panel 20 will be described as an OLED display panel, for example.

[0050] As Figure 3 and Figure 5 As shown in the figure, the display panel 20 may include a first substrate 201 and a pixel array layer PAL including a thin-film transistor (“TFT”) layer, a light-emitting element layer, and a thin-film encapsulation layer disposed on the first substrate 201. The display area of the display panel 20 refers to the planar area of the display panel 20 where the light-emitting element layer is provided or formed to display an image and / or emit light for displaying an image. The non-display area of the display panel 20 refers to the planar area adjacent to the display area of the display panel 20, such as extending from the display area to the outer edge of the display panel 20, but is not limited thereto. Since the light-transmitting portion DA10 of the cover window 10 is described as corresponding to the display panel 20, both the display area and the non-display area of the display panel 20 may correspond to the light-transmitting portion DA10 of the cover window 10, but is not limited thereto.

[0051] The first substrate 201 may be a relatively rigid substrate or may be a relatively flexible substrate that is bendable, foldable, or rollable. The first substrate 201 may include an insulating material such as glass, quartz, or a polymer material, or may be formed of an insulating material such as glass, quartz, or a polymer material. Examples of the polymer material include plastics such as polyethersulfone (“PES”), polyacrylate (“PA”), polyarylate (“PAR”), polyetherimide (“PEI”), polyethylene naphthalate (“PEN”), polyethylene terephthalate (“PET”), polyphenylene sulfide (“PPS”), polyallyl ester, polyimide (“PI”), polycarbonate (“PC”), triacetyl cellulose (“CAT”), cellulose acetate propionate (“CAP”), or a combination thereof. The first substrate 201 may include a metal material.

[0052] The TFT layer is provided on or formed on the first substrate 201. The TFT layer includes TFTs 235 (e.g., a plurality of TFTs 235) that can be provided as multiple, a gate insulating film 236, an interlayer insulating film 237, a passivation film 238, and a planarization film 239.

[0053] A buffer film 202 can be provided on or formed on the first substrate 201. The buffer film 202 can protect the moisture - sensitive TFTs 235 and light - emitting elements from moisture infiltration into the first substrate 201. In an embodiment, for example, the buffer film 202 can be provided as or formed into a multilayer film in which a silicon oxide (SiO x ) film, a silicon nitride (SiN x ) film, and / or a silicon oxynitride (SiON) film are alternately stacked. In an embodiment, the buffer film 202 can be omitted.

[0054] The TFTs 235 are provided on or formed on the buffer film 202. Each TFT 235 includes an active layer 231, a gate electrode 232, a source electrode 233, and a drain electrode 234. Figure 3 A top - gate structure in which the gate electrode 232 is disposed above the active layer 231 is shown for each TFT 235, but the present disclosure is not limited thereto. That is, the TFT 235 can have a bottom - gate structure in which the gate electrode 232 is disposed below the active layer 231 or a double - gate structure in which the gate electrode 232 is disposed both above and below the active layer 231.

[0055] The active layer 231 is provided on or formed on the buffer film 202. The active layer 231 can include a silicon - based semiconductor material or an oxide - based semiconductor material, or can be formed of a silicon - based semiconductor material or an oxide - based semiconductor material. A light - shielding layer (not shown) for blocking external light from incident on the active layer 231 can be provided on or formed between the buffer film 202 and the active layer 231.

[0056] The gate insulating film 236 can be provided on or formed on the active layer 231. The gate insulating film 236 can be provided as or formed into an inorganic film, such as, for example, a silicon oxide film, a silicon nitride film, or a multilayer film thereof.

[0057] The gate electrode 232 and the gate line can be provided on or formed on the gate insulating film 236. The gate electrode 232 and the gate line can be provided as or formed into a single - layer film or a multilayer film using molybdenum (Mo), aluminum, chromium (Cr), gold (Au), titanium (Ti), Ni, neodymium (Nd), Cu, or an alloy thereof.

[0058] An interlayer insulating film 237 may be provided on or formed on the gate electrode 232 and the gate line. The interlayer insulating film 237 may be provided or formed as an inorganic film, such as, for example, a silicon oxide film, a silicon nitride film, or a multilayer film thereof.

[0059] The source electrode 233, the drain electrode 234, and the data line may be provided on or formed on the interlayer insulating film 237. The source electrode 233 and the drain electrode 234 may be connected to the active layer 231 at or through contact holes that respectively penetrate the gate insulating film 236 and / or the interlayer insulating film 237. The source electrode 233, the drain electrode 234, and the data line may be provided or formed as a single-layer film or a multilayer film using Mo, Al, Cr, Au, Ti, Ni, Nd, Cu, or an alloy thereof.

[0060] A passivation film 238 may be provided on or formed on the source electrode 233, the drain electrode 234, and the data line to insulate the TFT 235. The passivation film 238 may be provided or formed as an inorganic film, such as, for example, a silicon oxide film, a silicon nitride film, or a multilayer film thereof.

[0061] A planarization film 239 may be provided on or formed on the passivation film 238 to planarize the height difference formed by the elements or layers in the TFT 235 and the elements or layers adjacent to the TFT 235. The planarization film 239 may be provided or formed as an organic film using an acrylic resin, an epoxy resin, a phenolic resin, a polyamide resin, or a polyimide resin.

[0062] The light-emitting element layer is provided on or formed on the TFT layer. The light-emitting element layer includes a light-emitting element and a pixel defining film 244.

[0063] The light-emitting element and the pixel defining film 244 are provided on or formed on the planarization film 239. The light-emitting element may be an OLED, respectively. In this case, each light-emitting element may include an anode electrode 241, a light-emitting layer 242, and a cathode electrode 243.

[0064] The anode electrode 241 may be provided on or formed on the planarization film 239. The anode electrode 241 may be connected to the source electrode 233 at or through a contact hole that penetrates the passivation film 238 and the planarization film 239.

[0065] The pixel defining film 244 may be provided or formed to cover the edge of the anode electrode 241 to define the pixels of the display panel 20. That is, the pixel defining film 244 may define a plurality of pixels. Such pixels may be arranged in the display area of the display panel 20, not limited to the display area. Each pixel may be an area where the anode electrode 241, the light emitting layer 242, and the cathode electrode 243 are sequentially stacked, and holes from the anode electrode 241 and electrons from the cathode electrode 243 are combined in the light emitting layer 242 to emit light.

[0066] The light emitting layer 242 may be provided or formed on the anode electrode 241 and the pixel defining film 244. The light emitting layer 242 may emit one of red light, green light, and blue light. Alternatively, the light emitting layer 242 may be a white light emitting layer that emits white light. In this case, the light emitting layer 242 may have a stack of a red light emitting layer, a green light emitting layer, and a blue light emitting layer, and may be a common layer provided or formed for all pixels, and the display panel 20 may further include color filters for respectively displaying red, green, and blue.

[0067] The light emitting layer 242 may include a hole transport layer, an emission layer, and an electron transport layer. The light emitting layer 242 may have a tandem structure having two or more stacks, and in this case, a charge generation layer may be provided or formed between the stacks.

[0068] The cathode electrode 243 may be provided or formed on the light emitting layer 242. The cathode electrode 243 may be provided or formed to cover the light emitting layer 242. The cathode electrode 243 may be a common layer provided or formed for all pixels.

[0069] In the case where the light-emitting element layer is provided as or formed into a top-emission type light-emitting element layer that emits light in a direction away from the first substrate 201 (e.g., in an upward direction), the anode electrode 241 may include a metal material having a relatively high reflectivity or be formed of a metal material having a relatively high reflectivity, such as a stack of Al and Ti (e.g., Ti / Al / Ti), a stack of Al and indium tin oxide ("ITO") (e.g., ITO / Al / ITO), a silver (Ag) palladium (Pd) copper (Cu) ("APC") alloy, or a stack of an APC alloy and ITO (e.g., ITO / APC / ITO), and the cathode electrode 243 may include a transparent conductive oxide ("TCO") material such as ITO or indium zinc oxide ("IZO") that allows light to transmit therethrough or a semi-transmissive conductive material such as magnesium (Mg), silver, or an alloy thereof, or may be formed of a transparent conductive oxide ("TCO") material such as ITO or indium zinc oxide ("IZO") that allows light to transmit therethrough or a semi-transmissive conductive material such as magnesium (Mg), silver, or an alloy thereof. In the case where the cathode electrode 243 includes or is formed of a semi-transmissive conductive material, the emission efficiency of the light-emitting element layer can be improved due to the microcavity effect.

[0070] In the case where the light-emitting element layer is provided as or formed into a bottom-emission type light-emitting element layer that emits light in a downward direction, the anode electrode 241 may include a TCO material such as ITO or IZO or a semi-transparent conductive material such as Mg, Ag, or an alloy thereof, or may be formed of a TCO material such as ITO or IZO or a semi-transparent conductive material such as Mg, Ag, or an alloy thereof, and the cathode electrode 243 may include a metal material having a relatively high reflectivity or be formed of a metal material having a relatively high reflectivity, such as a stack of Al and Ti (e.g., Ti / Al / Ti), a stack of Al and ITO (e.g., ITO / Al / ITO), an APC alloy, or a stack of an APC alloy and ITO (e.g., ITO / APC / ITO). In the case where the anode electrode 241 is formed of a semi-transparent conductive material, the emission efficiency of the light-emitting element layer can be improved due to the microcavity effect.

[0071] A thin film encapsulation layer is provided on or formed on a light-emitting element layer. The thin film encapsulation layer reduces or effectively prevents oxygen or moisture from penetrating into the light-emitting layer 242 and the cathode electrode 243. To this end, the thin film encapsulation layer may include at least one inorganic film. The inorganic film may include silicon nitride, aluminum nitride, zirconium nitride, titanium nitride, hafnium nitride, tantalum nitride, silicon oxide, aluminum oxide, or titanium oxide, or may be formed of silicon nitride, aluminum nitride, zirconium nitride, titanium nitride, hafnium nitride, tantalum nitride, silicon oxide, aluminum oxide, or titanium oxide. The thin film encapsulation layer may further include at least one organic film. The organic film may be provided or formed to a sufficient thickness to reduce or effectively prevent foreign particles from entering the light-emitting layer 242 and the cathode electrode 243 through the thin film encapsulation layer. The organic film may include one of epoxy resin, acrylate, and polyurethane acrylate.

[0072] Referring Figure 2 and Figure 5 , the display panel 20 may include a protruding area PA in a plan view, and the protruding area PA extends farther than the edge of the cover window 10. The protruding area PA is provided to extend on one side of the display panel 20. The display circuit board 30 and the display driving unit (not shown) may be attached to the display panel 20 at its protruding area PA. The first end of the display circuit board 30 may be attached to the pads or terminals of the display panel 20, such as via an anisotropic conductive film (not shown), and the pads or terminals of the display panel 20 are provided in the protruding area PA of the display panel 20. Various electrical signals such as control signals, data signals, driving signals, power supply signals, etc. may be transmitted from the display circuit board 30 to the display panel 20 at the pads or terminals of the display panel 20. The protruding area PA of the display panel 20 that connects the display circuit board 30 to it may be bent toward the bottom of the display panel 20.

[0073] Specifically, the display panel 20 may include a main area MR and a bending area BR where the display panel 20 can be bent.

[0074] In a plan view, the main area MR may have an external shape similar to that of the display device 1. In an embodiment, the main area MR may be a flat area located in one plane, but the present disclosure is not limited thereto. Alternatively, within the display device 1, at least one edge of all the edges of the main area MR except for the edge corresponding to or connected to the bending area BR may be bent or folded in the vertical direction instead of being located in one plane.

[0075] The bending area BR is connected to the main area MR at one side of its side extending along the first direction (or X-axis direction). In an embodiment, for example, the bending area BR may be at the lower part of the main area MR (e.g., Figure 2is connected to the main region MR at the relatively short side (e.g., the relatively short side of the main region MR). The widths of the main region MR and the curved region BR can be intercepted along the first direction (or the X-axis direction). The width of the curved region BR can be smaller than the width of the main region MR (e.g., the length of the relatively short side of the main region MR).

[0076] At the curved region BR, the display panel 20 can be curved with a curvature in the downward thickness direction (e.g., in the direction opposite to the display surface, or in the direction opposite to the Figure 1 and Figure 2 direction of the Z-axis shown). The curved display panel 20 can be set to have a consistent radius of curvature for the curved region BR, but the present disclosure is not limited thereto. Alternatively, the radius of curvature of the curved region BR in the curved display panel 20 can vary from one region of the curved region BR to another region of the curved region BR.

[0077] When the display panel 20 is curved at the curved region BR, a part of the display panel 20 can be flipped at the curved region BR. Referring to Figure 2 and Figure 5 , for example, the first surface of the display panel 20 at each of the main region MR, the curved region BR, and the protruding region PA can be set to face upward (e.g., along the Z-axis direction). The curved display panel 20 curved at the curved region BR sets a part of the first surface of the display panel 20 that is initially facing upward, facing outward (e.g., in the Figure 5 left direction in

[0078] and facing downward (e.g., in the direction opposite to the Z-axis direction). The sub-region SR of the display panel 20 extends from the curved region BR. The sub-region SR can define the distal part of the display panel 20. The pads or terminals provided in the protruding region PA of the display panel 20 can be provided at the sub-region SR, but are not limited thereto. The sub-region SR can extend from the point where the curvature of the display panel 20 is completed with respect to the plane where the main region MR is provided. The curved display panel 20 sets the sub-region SR overlapping the main region MR along the thickness direction of the display panel 20 and / or the display device 1. The curved display panel 20 can set the sub-region SR parallel to the main region MR, but is not limited thereto. In an embodiment, the first substrate 201 of the display panel 20 can define each of the curved region BR and the sub-region SR, but is not limited thereto.

[0079] The width of the sub-region SR can be the same as the width of the curved region BR, but the present disclosure is not limited thereto. In an embodiment, the curved region BR and the sub-region SR can define the protruding region PA of the display panel 20, but are not limited thereto.

[0080] The bottom member 40 of the panel can be disposed below the display panel 20. The bottom member 40 of the panel can be attached to the rear surface of the display panel 20, such as via an adhesive member. The adhesive member can be a pressure-sensitive adhesive ("PSA").

[0081] The bottom member 40 of the panel can include at least one of the following: a light absorption member for absorbing incident light from outside the display device 1, a buffer member for absorbing an impact from outside the display device 1, a heat dissipation member for effectively releasing heat from the display panel 20 to the outside thereof, and a light shielding layer for blocking incident light from outside the display device 1.

[0082] The light absorption member within the bottom member 40 of the panel can be disposed below the display panel 20. The light absorption member blocks the transmission of light, thereby reducing or effectively preventing elements (e.g., a display circuit board) disposed below the light absorption member from being visible from above the display panel 20 (e.g., the viewing side of the display device 1). The light absorption member can include a light absorption material such as a black pigment or dye.

[0083] The buffer member within the bottom member 40 of the panel can be disposed below the light absorption member. The buffer member absorbs an external impact, thereby reducing or effectively preventing the display panel 20 from being damaged. The buffer member can be provided as or formed into a single layer or multiple layers. In an embodiment, for example, the buffer member can include a polymer resin such as polyurethane, polycarbonate, polypropylene, or polyethylene, or an elastic material such as a sponge obtained by foaming rubber, a polyurethane-based material, or an acrylic material. The buffer member can be a cushion layer.

[0084] The heat dissipation member within the bottom member 40 of the panel can be disposed below the buffer member. The heat dissipation member can include: a first heat dissipation layer including graphite or carbon nanotubes; and a second heat dissipation layer provided as or formed into a relatively thin metal film using a metal such as Cu, nickel (Ni), ferrite, or Ag that can shield electromagnetic waves and has excellent thermal conductivity.

[0085] The display circuit board 30 can be attached to the bottom of the bottom member 40 of the panel. The display circuit board 30 can be attached to the bottom surface of the bottom member 40, such as via an adhesive member. The adhesive member can be a PSA. The bonding force between the display circuit board 30 and the PSA can be increased by increasing the contact area between the display circuit board 30 and the PSA. Due to the increased bonding force, bonding defects or peeling defects that occur in relation to process automation can be reduced or effectively prevented. This will be described in detail later.

[0086] Refer again to Figure 2 and Figure 5, an intermediate frame 50 may be provided below the panel bottom member 40, to which the panel bottom member 40 is attached and which has a display panel 20 covering the window 10. The intermediate frame 50 may include plastic, metal, or both.

[0087] The intermediate frame 50 may include holes defined therein, and components such as a camera device, a battery, and a cable may be provided in or pass through the holes.

[0088] The main circuit board 60 may be provided below the intermediate frame 50. The main circuit board 60 may be a printed circuit board (“PCB”) or a flexible PCB (“FPCB”).

[0089] The main circuit board 60 may include a main processor (not shown) that controls the functions of the display device 1 and / or components such as a camera device (not shown) of the main processor.

[0090] A mobile communication module may also be provided on the main circuit board 60, which may exchange wireless signals with at least one of a base station, an external terminal, and a server via a mobile communication network. The wireless signals may include various types of data related to the transmission / reception of audio signals, video call signals, and / or text / multimedia messages.

[0091] A lower cover 70 may be provided below the intermediate frame 50 and the main circuit board 60. The lower cover 70 may be coupled and fixed to the intermediate frame 50. The lower cover 70 may form the bottom located outside the display device 1. The lower cover 70 may include plastic and / or metal.

[0092] A camera hole into which a camera device is inserted may be provided or formed in the lower cover 70. The camera device inserted into the camera hole may be arranged such that a part of the camera device protrudes or is exposed to the outside of the display device 1.

[0093] The display circuit board 30 will be described below. Figure 6 is a plan view showing Figure 2 an embodiment of the display circuit board. Figure 7 is an enlarged cross-sectional view taken along Figure 6 line II-II' of

[0094] Referring to Figure 6 and Figure 7 , the display circuit board 30 may be an FPCB. Hereinafter, the display circuit board 30 will be described as the FPCB 300.

[0095] The FPCB 300 may include a base film 310, a conductive layer 320 disposed on the base film 310, a passivation layer 330 disposed on the conductive layer 320, and a first adhesive 340 disposed on the passivation layer 330. The passivation layer 330 defines an outer surface of the FPCB 300 to which a target object such as the display panel 20 can be attached.

[0096] The base film 310 may include, for example, a flexible insulating material such as PI, or may be formed of a flexible insulating material such as PI.

[0097] The conductive layer 320 may be disposed on the base film 310. The conductive layer 320 may form or define pads or terminals of the display circuit board 30 together with its plurality of electrical signal lines. The conductive layer 320 may include a metallic material such as Cu, or may be formed of a metallic material such as Cu.

[0098] The passivation layer 330 may serve as an insulating member between the electronic circuit and a passivation member for protecting the circuit pattern within the FPCB 300. Such a circuit pattern may be connected to conductive elements of the display panel 20, such as terminals or pads, signal lines, etc. The passivation layer 330 may include a resin layer 331 and a plurality of fillers 333 (e.g., a plurality of fillers 333) dispersed in the resin layer 331. Since the fillers 333 are dispersed in the resin layer 331, the mechanical properties of the passivation layer 330 can be improved.

[0099] The resin layer 331 may include a thermosetting compound. The resin layer 331 may include an organic material. The thermosetting compound may be an epoxy resin, and the epoxy resin may be selected from naphthalene-based epoxy resins, naphthol / phenol-based epoxy resins, olefin-based epoxy resins, cresol novolac epoxy resins, bisphenol A epoxy resins, diglycidyl ethers of bisphenol A (DGEBA)-based epoxy resins, diglycidyl ethers of bisphenol F (DGEBF)-based epoxy resins, and rubber-modified epoxy resins.

[0100] The fillers 333 may include an inorganic material. In an embodiment, for example, the fillers 333 may be selected from silica, alumina, barium sulfate, talc, clay, mica powder, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum borate, barium calcium titanate, magnesium titanate, bismuth titanate, titanium carbonate, titanium oxide, barium titanate, zircon, and calcium zirconate. The fillers 333 may include one of the materials listed above, or may be formed of one of the materials listed above, and at least two of the fillers 333 may be used in combination.

[0101] The filler 333 may be included in the passivation layer 330 in an amount of about 50 parts by weight to about 80 parts by weight relative to the total weight of the passivation layer 330. When the content of the filler 333 is less than about 50 parts by weight, the hardness of the passivation layer 330 provided or formed by the resin layer 331 may decrease. When the content of the filler 333 is greater than about 80 parts by weight, the fluidity of the resin layer 331 decreases, and thus, the flatness and uniformity of the passivation layer 330 including the resin layer 331 deteriorate. Therefore, the bonding strength between the passivation layer 330 and components attached to the FPCB 300 at the passivation layer 330, such as the panel bottom member 40 for example, decreases.

[0102] The passivation layer 330 may include a first region S1 and a second region S2 which is the remaining region of the passivation layer 330 other than the first region S1. That is, the second region S2 may correspond to the entire outer surface of the passivation layer 330 except for the outer surface in the first region S1.

[0103] The first region S1 of the passivation layer 330 may include a recessed portion recessed from the second region S2, for example, a recessed portion recessed from the top surface of the passivation layer 330 defined at the second region S2. The top surface of the passivation layer 330 defines the outer surface of the FPCB 300, and this outer surface is provided at both the first region S1 and the second region S2. The first region S1 may be a planar region of the passivation layer 330 to which the first adhesive 340 can be attached. The first region S1 may be a planar region at which the passivation layer 330 (or the FPCB 300) can be attached to the rear surface of the display panel 20. This will be described in detail later.

[0104] The recessed portion at the first region S1 may include a bottom surface located at the center of the first region S1 and side surfaces extending from the bottom surface and reaching the top surface at the second region S2 to effectively surround the bottom surface in a plan view, or may be defined by a bottom surface located at the center of the first region S1 and side surfaces extending from the bottom surface and reaching the top surface at the second region S2 to effectively surround the bottom surface in a plan view. That is, the recessed portion is defined by the bottom surface and side surfaces connecting the bottom surface and the outer surface at the second region S2 to each other. The side surfaces of the recessed portion at the first region S1 may have a predetermined inclination angle with respect to the top surface of the second region S2, and may connect the bottom surface of the recessed portion at the first region S1 and the top surface of the passivation layer 330 at the second region S2 to each other. The bottom surface and side surfaces at the recessed portion together with the top surface at the second region S2 may define the entire top surface (or outer surface) of the passivation layer 330.

[0105] The second region S2 may occupy the entire planar region of the passivation layer 330 except for the planar region defined by the first region S1. The second region S2 where the first adhesive 340 is omitted may be exposed from the first adhesive 340 to the outside of the passivation layer 330 (or the outside of the FPCB 300).

[0106] In a plan view, the first region S1 may partially overlap with the first adhesive 340. The passivation layer 330 at its first region S1 may be in direct contact with the first adhesive 340. The overlapping area of the first adhesive 340 with the first region S1 of the passivation layer 330 is greater than the overlapping area of the first adhesive 340 with the second region S2 of the passivation layer 330.

[0107] The passivation layer 330 at its first region S1 may include fillers 333 protruding beyond the surface of the resin layer 331. The fillers 333 may protrude more than the resin layer 331 at each of the bottom surface and the side surface of the recess. The number of fillers 333 in the recess at the first region S1 exposed to the outside of the resin layer 331 may be greater than the number of fillers 333 at the second region S2 exposed to the outside of the resin layer 331. The attachment of the first adhesive 340 at the first region S1 of the passivation layer 330 sets the first adhesive 340 to be in contact with both the resin layer 331 and the fillers 333 exposed to the outside of the resin layer 331.

[0108] The passivation layer 330 at the first region S1 may have a predetermined surface roughness. The surface roughness at the first region S1 may be defined by the fillers 333 in the recess at the first region S1 exposed to the outside of the resin layer 331. The surface roughness at the first region S1 may be provided or formed by a plasma etching process. The surface roughness at the first region S1 may be greater than the surface roughness at the second region S2. Only the first region S1 may be provided or formed to have surface roughness, and actually no surface roughness may be provided or formed in the second region S2 (e.g., completely smooth or flat). In addition, the surface roughness at the first region S1 may vary from one part of the first region S1 to another part. In an embodiment, for example, the surface roughness at the bottom surface of the recess within the first region S1 may be greater than the surface roughness at the side surface of the recess within the first region S1.

[0109] As described above, since the filler 333 further protrudes from the resin layer 331 at the first region S1 to increase the surface area and surface roughness of the passivation layer 330 at the first region S1, the adhesion strength of the adhesive attached to the first region S1 of the passivation layer 330 can be improved, particularly the adhesion strength of the adhesive at the interface between the adhesive and the first region S1 of the passivation layer 330. Specifically, in the case where the adhesive is attached to the same planar region of the first region S1 and the second region S2, since the surface area provided by the recessed portion at the first region S1 increases, the actual contact area between the first region S1 and the adhesive can be larger than the actual contact area between the second region S2 and the adhesive. That is, the adhesion strength between the first region S1 and the adhesive can be greater than the adhesion strength between the second region S2 and the adhesive. In this case, the adhesive can be more easily separated from the second region S2 than from the first region S1.

[0110] The passivation layer 330 may have a first thickness H1 and a second thickness H2.

[0111] The bottom surface of the recessed portion at the first region S1 may be the part of the entire top surface of the passivation layer 330 closest to the base film 310. The first thickness H1 may be defined as the shortest distance between the entire top surface of the passivation layer 330 and the bottom surface of the passivation layer 330.

[0112] The second thickness H2 may be defined as the shortest distance between the lowest point of the second region S2 of the passivation layer 330 and the bottom surface of the passivation layer 330. In other words, the second thickness H2 may be the longest distance between the bottom surface and the entire top surface of the passivation layer 330.

[0113] The first thickness H1 may be less than the second thickness H2. The average thickness (e.g., the first thickness H1) of the passivation layer 330 at the first region S1 may be less than the average thickness (e.g., the second thickness H2) of the passivation layer 330 at the second region S2.

[0114] The depth of the recessed portion at the first region S1 of the passivation layer 330 may be expressed as the difference between the first thickness H1 and the second thickness H2, that is, H2 minus H1 (e.g., H2 - H1).

[0115] The first adhesive 340 may be provided on the passivation layer 330. Specifically, the first adhesive 340 may be provided in the first region S1 of the passivation layer 330. The first adhesive 340 may at least partially overlap with the first region S1 of the passivation layer 330 and may be in direct contact with the first region S1 of the passivation layer 330. Figure 7The side surface of the first adhesive 340 is shown to be aligned with the side surface of the recess at the first region S1, but the present disclosure is not limited thereto. Alternatively, the side surface of the first adhesive 340 may be inside the first region S1 with a planar size smaller than that of the first region S1. In this case, a portion of the passivation layer 330 (e.g., at the recess) may be exposed from the first adhesive 340.

[0116] The first adhesive 340 may include a first adhesive layer 341A, a first substrate layer 343 disposed on the first adhesive layer 341A, and a second adhesive layer 341B disposed on the first substrate layer 343.

[0117] The first adhesive layer 341A may be disposed between the passivation layer 330 and the first substrate layer 343. The first surface of the first adhesive layer 341A may be in direct contact with the passivation layer 330, and the second surface of the first adhesive layer 341A opposite to its first surface may be in direct contact with the first surface of the first substrate layer 343. Specifically, the first surface of the first adhesive layer 341A may be in direct contact with the first region S1 of the passivation layer 330. In addition, the first surface of the first adhesive layer 341A may be in direct contact not only with the resin layer 331 in the first region S1 but also with the filler 333 protruding from the resin layer 331 in the first region S1.

[0118] The second adhesive layer 341B may be disposed on the first substrate layer 343, and a first release layer 360A ( Figure 15 and Figure 16 ) may be removably disposed on the second adhesive layer 341B. The first surface of the second adhesive layer 341B may be in direct contact with the second surface of the first substrate layer 343 opposite to its first surface, and the second surface of the second adhesive layer 341B may be in direct contact with the first surface of the first release layer 360A. The first release layer 360A removably disposed on the second adhesive layer 341B may be removed during the assembly process of the FPCB 300. Then, a target object may be attached to the FPCB 300, such as bringing the target object into contact with the second adhesive layer 341B from which the first release layer 360A has been removed. In an embodiment, for example, once the first release layer 360A is removed, the second surface of the second adhesive layer 341B may be in contact with the rear surface of the display panel 20, but the present disclosure is not limited thereto. In the case where the panel bottom member 40 or the like is provided at the bottom of the display panel 20, the second surface of the second adhesive layer 341B from which the first release layer 360A has been removed may be in contact with the panel bottom member 40. Therefore, the FPCB 300 may be coupled to the display panel 20 or the panel bottom member 40 via the second adhesive layer 341B.

[0119] The first adhesive layer 341A and / or the second adhesive layer 341B may include an acrylic resin or a silicone resin. The first adhesive layer 341A and the second adhesive layer 341B may include the same material or may be formed of the same material.

[0120] The first adhesive layer 341A and the second adhesive layer 341B may have different adhesive strengths from each other. Specifically, the adhesive strength of the first adhesive layer 341A may be greater than the adhesive strength of the second adhesive layer 341B. Accordingly, the bonding force between the first adhesive layer 341A and the passivation layer 330 may be stronger than the bonding force between the second adhesive layer 341B and the first release layer 360A. Thus, even if the first release layer 360A is removed from the second adhesive layer 341B during the assembly process, the removal of the first adhesive layer 341A from the passivation layer 330 can be reduced or effectively prevented.

[0121] The first substrate layer 343 may be disposed between the first adhesive layer 341A and the second adhesive layer 341B. The first surface of the first substrate layer 343 may be in direct contact with the second surface of the first adhesive layer 341A, and the second surface of the first substrate layer 343 may be in direct contact with the first surface of the second adhesive layer 341B.

[0122] The first substrate layer 343 may be provided as a support layer for the first adhesive 340.

[0123] The first substrate layer 343 may include a film of a transparent material such as PET, thermoplastic polyurethane (“TPU”), PC, polyvinyl chloride (“PVC”), or polypropylene (“PP”).

[0124] Figure 7 The first substrate layer 343 disposed between the first adhesive layer 341A and the second adhesive layer 341B is shown, but the present disclosure is not limited thereto. Alternatively, instead of providing the first substrate layer 343 between the first adhesive layer 341A and the second adhesive layer 341B, an intermediate adhesive layer may be provided.

[0125] As described above, an increased surface roughness may be imparted only to the first region S1 of the passivation layer 330 without affecting other regions of the passivation layer 330.

[0126] In addition, since the increased surface roughness is provided in or formed in the first region S1 of the passivation layer 330, the contact area between the first region S1 and the first adhesive 340 can be increased. Accordingly, the bonding strength between the first region S1 of the passivation layer 330 and the first adhesive 340 can be improved. Thus, bonding defects or peeling defects that may occur in connection with the automation of the process of assembling the FPCB 300 to a target object can be reduced or effectively prevented.

[0127] In the following, a modified embodiment of the FPCB will be described. In Figure 7 and Figure 8 throughout this disclosure, like reference numerals denote like elements and their description will be omitted or at least simplified.

[0128] Figure 8 is an enlarged cross-sectional view showing another embodiment of the circuit board 30.

[0129] Referring to Figure 8 , the FPCB 300_1 is different from the FPCB 300 of Figure 7 in that the first adhesive 340' partially overlaps with the second region S2 of the passivation layer 330.

[0130] Specifically, in a plan view, the planar dimension of the first adhesive 340' may be larger than the planar dimension of the first region S1 of the passivation layer 330. Thus, the first adhesive 340' may be arranged to completely cover the first region S1 of the passivation layer 330 and extend more than the first region S1 to be disposed in the second region S2. That is, the overlapping area of the first adhesive 340' with the first region S1 of the passivation layer 330 is larger than the overlapping area of the first adhesive 340' with the second region S2 of the passivation layer 330.

[0131] The first adhesive 340' may be in contact with the first region S1 and the second region S2 of the passivation layer 330. The total contact area of the first adhesive 340' with the passivation layer 330 at the first region S1 may be larger than the total contact area of the first adhesive 340' with the passivation layer 330 at the second region S2.

[0132] Figure 8 shows that the base layer 343' of the first adhesive 340' is disposed outside the passivation layer 330 to be in contact with the second region S2 of the passivation layer 330, but the present disclosure is not limited thereto. That is, in the case where the first adhesive layer 341A' of the first adhesive 340' is provided or formed to be thicker than the depth of the recess at the first region S1 of the passivation layer 330 (e.g., greater than H2 - H1), the first adhesive layer 341A' may extend to the outside of the recess to be in contact with the second region S2 of the passivation layer 330.

[0133] As Figure 7 similarly shown, Figure 8 the edge of the second adhesive layer 341B' shown in

[0134] Surface roughness can be applied only to the first region S1 of the passivation layer 330 without affecting other regions of the passivation layer 330. In addition, as described above, since surface roughness is provided or formed in the first region S1 of the passivation layer 330, the adhesion strength between the first region S1 and the first adhesive 340' can be improved. Therefore, adhesion defects or peeling defects that may occur in relation to process automation can be prevented.

[0135] Hereinafter, a method of manufacturing a display circuit board (e.g., FPCB 300) will be described. Specifically, a method of manufacturing the Figures 1 to 7 FPCB 300 will be described. In Figures 1 to 7 and Figure 9 throughout the present disclosure, the same reference numerals denote the same elements, and their description will be omitted or at least simplified.

[0136] Figure 9 is a flowchart showing an embodiment of a method of manufacturing a display circuit board (e.g., FPCB 300). Figures 10 to 17 is a cross-sectional view showing an embodiment of respective structures in a process of a method of manufacturing a display circuit board (e.g., FPCB 300). Figures 10 to 17 is along Figure 6 The cross-sectional view taken along line II-II'.

[0137] Referring to Figure 9 , a method of manufacturing a display circuit board (e.g., FPCB 300) may include: providing or forming a conductive layer (S1) on a base film; providing or forming a resin material layer including a filler on the conductive layer (S2); performing a plasma etching process on the resin material layer using a mask (S3); providing or forming a passivation layer by curing the resin material layer (S4); attaching a first adhesive and a first release layer to a first region of the passivation layer (S5); attaching a second adhesive and a second release layer to a second region of the passivation layer (S6); removing the first release layer from the first adhesive (S7); and removing the second adhesive and the second release layer from the passivation layer (S8).

[0138] Referring to Figure 9 and Figure 10 , a conductive layer 320 is provided or formed on a base film 310 (S1). The conductive layer 320 may include a metal material such as Cu or be formed of a metal material such as Cu, and the conductive layer 320 may form a circuit pattern of the FPCB 300 on its base film 310.

[0139] Thereafter, referring to Figure 9 and Figure 11, a resin material layer 331' including a filler 333 is provided or formed on the conductive layer 320 (S2). Specifically, the resin material layer 331' in a semi-cured state (e.g., the semi-cured resin material layer 331') is provided or formed by coating the resin material and drying the resin material. At least one of screen printing, roll coating, curtain coating, and spraying can be used to coat the resin material. The resin material layer 331' can include a thermosetting compound such as an epoxy resin. The resin material layer 331' including the filler 333 defines an inner surface facing the conductive layer 320 and an outer surface opposite to the inner surface.

[0140] Thereafter, referring to Figure 9 and Figure 12 , a plasma etching treatment process P (e.g., plasma etching) is performed on the resin material layer 331' using a mask M (S3).

[0141] A plasma generation gas including O 2 or CF 4 can be used to perform the plasma etching treatment process P. The surface roughness of the resin material layer 331' can be controlled according to the composition ratio of the plasma generation gas.

[0142] The first region S1 of the resin material layer 331' is exposed to the plasma etching treatment process P using the mask M, and the plasma etching treatment process P is performed while masking the second region S2 therefrom. Therefore, the first region S1 of the resin material layer 331' can be selectively etched by the plasma etching treatment process P. In this case, the outer surface of the resin material layer 331' in the first region S1 is given a surface roughness by the plasma etching treatment process P, while the inner surface of the resin material layer 331' faces the conductive layer 320. Specifically, when etching the first region S1 of the resin material layer 331', the filler 333 dispersed in the resin material layer 331' at the first region S1 can be exposed to the outside of the resin material layer 331' in the first region S1. At the first region S1, the total thickness of the resin material layer 331' in which the filler 333 is dispersed is reduced by the plasma etching treatment process P. This reduction in the total thickness forms a recessed portion of the resin material layer 331' at the first region S1, and the filler 333 at the recessed portion protrudes to the outside of the resin material layer 331'.

[0143] As described above, since the filler 333 protrudes outside the resin material layer 331' in the first region S1, the surface area of the resin material layer 331' at the first region S1 can be increased. Since the surface roughness of the resin material layer 331' is provided or formed in the first region S1, the adhesion strength of the resin material layer 331' at the interface between the first region S1 and the adhesive can be improved and enhanced. Specifically, in the case where the adhesive adheres to the resin material layer 331' at the first region S1 and the second region S2, the contact area between the resin material layer 331' at the first region S1 and the adhesive can be larger than the contact area between the resin material layer 331' at the second region S2 and the adhesive. That is, the adhesion strength between the resin material layer 331' at the first region S1 and the adhesive can be greater than the adhesion strength between the resin material layer 331' at the second region S2 and the adhesive. In this case, the adhesive can be more easily separated from the resin material layer 331' at the second region S2 than from the resin material layer 331' at the first region S1.

[0144] Thereafter, referring to Figure 9 and Figure 13 , a passivation layer 330 (e.g., a cured passivation layer 330) is provided or formed by curing the resin material layer 331' in which the filler 333 is dispersed (S4). The resin material layer 331' can be thermally cured or optically cured. Although not specifically shown, before forming the passivation layer 330 by curing the resin material layer 331', processes such as providing or forming vias in the resin material layer 331' can be performed.

[0145] The curing of the resin material layer 331' provides the resin layer 331 including the first region S1 of the passivation layer 330 that has been plasma-etched from the first region S1 of the resin material layer 331' that has been plasma-etched, and provides the second region S2 from the second region S2 of the resin material layer 331'. That is, the first region S1 and the second region S2 of the passivation layer 330 respectively correspond to the first region S1 and the second region S2 of the above resin material layer 331', and are respectively provided from the first region S1 and the second region S2 of the above resin material layer 331'.

[0146] Thereafter, referring to Figure 9 and Figure 14 , a first adhesive 340 and a first release layer 360A are attached to the passivation layer 330 at the first region S1 of the passivation layer 330 (S5). A silicone-based film, a PET-based film, or a paper-based film can be used as the first release layer 360A.

[0147] As described above, due to the plasma etching process P, the filler 333 protrudes from the resin layer 331 at the first region S1. Therefore, the first adhesive 340 can have an improved adhesion strength to the passivation layer 330 at the first region S1.

[0148] Thereafter, with reference to Figure 9 and Figure 15 , the second adhesive 350 and the second release layer 360B are attached to the passivation layer 330 (S6) at the second region S2 of the passivation layer 330. The second adhesive 350 and the second release layer 360B can be provided over the entire second region S2 except for the first region S1, but are not limited thereto. Since the second adhesive 350 is attached to the passivation layer 330 at the second region S2 where the filler 333 does not protrude outside the resin layer 331, the adhesion strength between the second adhesive 350 and the passivation layer 330 at its second region S2 may be less than the adhesion strength between the first adhesive 340 and the passivation layer 330 at its first region S1. Therefore, after the assembly process using the second adhesive 350, the second adhesive 350 can be relatively easily peeled off and removed from the passivation layer 330. That is, the second adhesive 350 is removably provided on the passivation layer 330, and in particular, the second adhesive 350 is removably provided at the second region S2 of the passivation layer 330.

[0149] The second adhesive 350 may include a third adhesive layer 351A, a second base layer 353 provided on the third adhesive layer 351A, and a fourth adhesive layer 351B provided on the second base layer 353.

[0150] The third adhesive layer 351A may be provided between the passivation layer 330 and the second base layer 353. The first surface of the third adhesive layer 351A may be in direct contact with the passivation layer 330, and the second surface of the third adhesive layer 351A may be in direct contact with the first surface of the second base layer 353. Specifically, the first surface of the third adhesive layer 351A may be in direct contact with the second region S2 of the passivation layer 330. In addition, the first surface of the third adhesive layer 351A may be in direct contact with the resin layer 331 in the second region S2, but not in direct contact with the filler 333 of the passivation layer 330 in the second region S2.

[0151] The fourth adhesive layer 351B may be provided on the second base layer 353, and the second release layer 360B may be provided on the fourth adhesive layer 351B. The first surface of the fourth adhesive layer 351B may be in direct contact with the second surface of the second base layer 353, and the second surface of the fourth adhesive layer 351B may be in direct contact with the first surface of the second release layer 360B.

[0152] The third adhesive layer 351A and / or the fourth adhesive layer 351B may include an acrylic resin or a silicone resin. The third adhesive layer 351A and the fourth adhesive layer 351B may include the same material or may be formed of the same material.

[0153] The third adhesive layer 351A and the fourth adhesive layer 351B may have different adhesive strengths from each other. Specifically, the adhesive strength of the third adhesive layer 351A may be less than the adhesive strength of the fourth adhesive layer 351B. Accordingly, the bonding force between the third adhesive layer 351A and the passivation layer 330 may be weaker than the bonding force between the fourth adhesive layer 351B and the first release layer 360A.

[0154] In addition, the adhesive strength of the first adhesive layer 341A may be greater than the adhesive strength of the third adhesive layer 351A. In addition, the adhesive strength of the second adhesive layer 341B may be less than the adhesive strength of the fourth adhesive layer 351B.

[0155] The second substrate layer 353 may be disposed between the third adhesive layer 351A and the fourth adhesive layer 351B. The first surface of the second substrate layer 353 may be in direct contact with the second surface of the third adhesive layer 351A, and the second surface of the second substrate layer 353 may be in direct contact with the first surface of the fourth adhesive layer 351B.

[0156] The second substrate layer 353 may be provided as a support layer for the second adhesive 350.

[0157] The second substrate layer 353 may include a film of a transparent material such as PET, TPU, PC, PVC, or PP.

[0158] The second substrate layer 353 may include the same material as the first substrate layer 343. The second substrate layer 353 may be substantially the same as the first substrate layer 343.

[0159] A silicone-based film, a PET-based film, or a paper-based film may be used as the second release layer 360B. The second release layer 360B may include the same material as the first release layer 360A. The second release layer 360B may be substantially the same as the first release layer 360A.

[0160] Thereafter, referring to Figure 9 and Figure 16, the first release layer 360A is removed from the first adhesive 340 (S7). That is, the first release layer 360A is removably provided on the first adhesive 340. As described above, since the first adhesive 340 is in contact with the passivation layer 330 at the first region S1 that has undergone the plasma etching process P, the first adhesive 340 can be relatively firmly coupled to the passivation layer 330 at its first region S1. Thus, even if the first release layer 360A is removed from the first adhesive 340, the peeling of the first adhesive 340 from the passivation layer 330 can be reduced or effectively prevented.

[0161] In addition, since the adhesive strength of the first adhesive layer 341A is greater than that of the second adhesive layer 341B, the bonding force between the first adhesive layer 341A and the passivation layer 330 can be stronger than the bonding force between the second adhesive layer 341B and the first release layer 360A. Therefore, the first release layer 360A can be relatively easily removed while reducing or effectively preventing the peeling of the first adhesive 340 from the passivation layer 330.

[0162] Once the first release layer 360A is removed from the first adhesive 340, the target object can come into contact with the second adhesive layer 341B. In an embodiment, for example, the second surface of the second adhesive layer 341B from which the first release layer 360A has been removed can come into contact with the rear surface of the display panel 20 as the target object, but the present disclosure is not limited thereto. Alternatively, in the case where a panel bottom member 40 or the like is provided at the bottom of the display panel 20, the second surface of the second adhesive layer 341B can come into contact with the panel bottom member 40 as the target object. Thus, the FPCB 300 can be coupled to the display panel 20 or to the panel bottom member 40 via the second adhesive layer 341B exposed by removing the first release layer 360A. That is, the first adhesive 340 can be used as an adhesive for joining components to each other.

[0163] Thereafter, referring to Figure 9 and Figure 17, the second adhesive 350 and the second release layer 360B are removed from the passivation layer 330 to complete the FPCB 300 (S8). The second adhesive 350 and the second release layer 360B may be adhesives for automating the process of assembling components to implement the FPCB 300 and / or the display device 1. In this case, after the assembly process, the second adhesive 350 and the second release layer 360B may be removed together. That is, the second adhesive 350 is removably disposed on the FPCB 300 together with the second release layer 360B. Since the second adhesive 350 contacts the passivation layer 330 at the second region S2 that has not yet undergone the plasma etching process P, the bonding force of the second adhesive 350 with respect to the passivation layer 330 is relatively weak. Thus, during the removal of the second release layer 360B, the second adhesive 350 can be peeled off from the passivation layer 330 together with the second release layer 360B.

[0164] In addition, since the bonding strength of the third adhesive layer 351A is less than the bonding strength of the fourth adhesive layer 351B, the bonding force between the third adhesive layer 351A and the passivation layer 330 may be weaker than the bonding force between the fourth adhesive layer 351B and the second release layer 360B. Therefore, the second adhesive 350 can be easily peeled off, and thus, defects caused by any residual adhesive used for assembling components can be reduced or effectively prevented.

[0165] Figures 9 to 17 It is shown that the first release layer 360A is removed first, and then the second release layer 360B is removed, but the present disclosure is not limited thereto. Alternatively, the first release layer 360A and the second release layer 360B may be removed simultaneously. Still alternatively, the second release layer 360B may be removed first, and then the first release layer 360A may be removed.

[0166] However, the effects of the embodiments are not limited to the effects described herein. By referring to the present disclosure, the above and other effects of the embodiments will become more apparent to those of ordinary skill in the art to which the embodiments pertain.

[0167] Although the embodiments of the present disclosure have been disclosed for illustrative purposes, those skilled in the art will understand that various modifications, additions, and substitutions can be made without departing from the scope and spirit of the present disclosure as disclosed herein.

Claims

1. A display device, wherein, the display device includes: a display panel including a display surface and a rear surface opposite to the display surface; and a flexible printed circuit board that can be attached to the display panel at the rear surface of the display panel, wherein, the flexible printed circuit board includes a conductive layer, a passivation layer defining an outer surface of the flexible printed circuit board, and a base film facing the passivation layer, and the conductive layer is between the passivation layer and the base film, the outer surface includes: a first region of the passivation layer where the rear surface of the display panel can be attached to the flexible printed circuit board; and a second region of the passivation layer where the rear surface of the display panel is not attached to the flexible printed circuit board, and the first region of the passivation layer has a larger surface roughness than the second region of the passivation layer.

2. The display device according to claim 1, wherein, the display device further includes: a first adhesive that can be attached to the display panel and can be attached to the passivation layer at the first region of the passivation layer.

3. The display device according to claim 2, wherein, the overlapping area of the first adhesive with the first region of the passivation layer is larger than the overlapping area of the first adhesive with the second region of the passivation layer.

4. The display device according to claim 3, wherein, inside the flexible printed circuit board, the passivation layer includes a resin layer and fillers dispersed in the resin layer.

5. The display device according to claim 4, wherein, at the first region of the passivation layer, the fillers protrude from the resin layer to be exposed outside the resin layer.

6. The display device according to claim 5, wherein, the attachment of the first adhesive at the first region of the passivation layer sets the first adhesive to contact both the resin layer and the fillers exposed outside the resin layer.

7. The display device according to claim 2, wherein, the first adhesive includes: a first adhesive layer where the first adhesive can be attached to the passivation layer at the first region of the passivation layer; a second adhesive layer where the first adhesive can be attached to the display panel; and a first matrix layer between the first adhesive layer and the second adhesive layer, and the bonding strength of the first adhesive layer is greater than the bonding strength of the second adhesive layer.

8. The display device according to claim 1, wherein, the average thickness of the passivation layer at the first region of the passivation layer is less than the average thickness of the passivation layer at the second region of the passivation layer.

9. The display device according to claim 8, wherein, the first region of the passivation layer is a plasma etching region of the passivation layer.

10. The display device according to claim 1, wherein, At the first region, the passivation layer defines a recess that is recessed from the outer surface at the second region, the recess being defined by a bottom surface and side surfaces connecting the bottom surface and the outer surface at the second region, and the surface roughness of the passivation layer at the bottom surface of the recess is greater than the surface roughness of the side surfaces of the recess.

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