Light source unit and display device including the same

Abstract

A light source unit for a display device includes: a printed circuit board including a pad located on a substrate and including a copper layer, and a first diffusion barrier pattern located on the pad and including a molybdenum alloy; and a light emitting diode mounted on the pad through a solder resist. In one embodiment, the printed circuit board is a glass printed circuit board.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2020-0175042 filed in Korea on December 15, 2020, which is incorporated herein by reference in its entirety for all purposes as if fully set forth herein. Technical Field

[0003] The present disclosure relates to a display device including a light source unit, and more particularly, to a display device capable of preventing a light emitting diode (LED) or a connector of the light source unit from being detached. Background Art

[0004] Recently, with the development of information technology and mobile communication technology, the development of display devices that visually display information has been carried out. The display devices are divided into self-luminous type display devices having light-emitting characteristics and non-self-luminous type display devices that display images using external factors.

[0005] As an example of a non-self-luminous display device that does not have a self-luminous element, a liquid crystal display (LCD) device is used.

[0006] The LCD device, which is a non-self-luminous display device, requires an additional light source. A backlight unit including a light source located at the rear of the LCD device is provided and light is irradiated toward the front of the LCD device, thereby realizing a recognizable image.

[0007] The backlight unit uses a cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp (EEFL), or a light emitting diode (LED) as a light source.

[0008] Among these light sources, LEDs are particularly small in size, low in power consumption, and high in reliability, and have been widely used.

[0009] According to the arrangement of LEDs, backlight units are generally divided into side light type units and direct light type units. The structure of the side light type backlight unit is that the LEDs are arranged on one side surface or both sides of the light guide plate, and the side light emitted by the LEDs is converted into planar light through the light guide plate and irradiated onto the display panel.

[0010] The direct type backlight unit has LEDs disposed under a display panel and directly emits light toward the display panel.

[0011] Recently, due to consumer demands, large display devices are actively studied, and a direct type backlight unit is more suitable for the large display device than an edge type backlight unit.

[0012] In addition, the direct-type backlight unit can improve the uniformity and brightness of light emitted to the display panel, can implement local dimming driving, thereby improving contrast, and can achieve reduced power consumption.

[0013] The direct type backlight unit includes a light source, which is composed of a plate circuit board and a plurality of LEDs mounted on the circuit board and spaced apart from each other at constant intervals. The circuit board on which the LED is mounted can use, for example, a (printed circuit board) PCB, a (metal core or metal-clad PCB) MCPCB, a (metal PCB) MPCB, a (flexible PCB) FPCB or the like.

[0014] Since the circuit board is generally formed of a substrate of synthetic resin or insulating material, the circuit board has problems of low thermal conductivity and poor flatness.

[0015] When the thermal conductivity of the circuit board is low, the heat emitted from the circuit board is relatively low, causing malfunction of the mounted LED or shortening the life of the mounted LED.

[0016] When the flatness of the circuit board is poor, poor bonding of fine patterns formed on the circuit board may occur.

[0017] The above problems will eventually affect the production efficiency or reduce the yield of the circuit board, thereby increasing the production cost and reducing the efficiency of the manufacturing process. Summary of the invention

[0018] Accordingly, the present disclosure is directed to a display device that substantially obviates one or more problems due to limitations and disadvantages of the related art.

[0019] One advantage of the present disclosure is to provide a display device that may include a circuit board having good thermal conductivity.

[0020] Another advantage of the present disclosure is to provide a display device that can reduce production costs and improve process efficiency.

[0021] Other features and advantages of the present disclosure will be described in the following description, and part will be obvious from the description, or can be learned by the practice of the present disclosure. These and other advantages of the present disclosure will be realized and obtained by the structures particularly pointed out in the written description and its claims and the accompanying drawings.

[0022] To achieve these and other advantages and in accordance with the purposes of the present disclosure, as embodied and broadly described herein, a light source unit for a display device includes: a printed circuit board (PCB) including a pad located on a substrate and including a copper (Cu) layer; and a first diffusion barrier pattern located on the pad and including a molybdenum (Mo) alloy; and a light emitting diode (LED) mounted on the pad through a solder resist. In one embodiment, the printed circuit board is a glass printed circuit board, and in one embodiment, the substrate on which the pad is located is a glass substrate including copper.

[0023] In another embodiment, a display device includes: a light source unit including a glass printed circuit board (PCB) and a plurality of light emitting diodes (LEDs) mounted on the glass PCB; an optical unit located on the light source unit; and a display panel located on the optical unit, wherein the glass PCB includes a pad and a first diffusion barrier pattern, and wherein the LED is mounted on the pad through a solder resist.

[0024] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the disclosure as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification, and illustrate embodiments of the present disclosure and together with the description serve to explain the principles of the present disclosure. In the drawings:

[0026] Figure 1 is an exploded perspective view illustrating a display device according to an embodiment of the present disclosure;

[0027] Figure 2 is a cross-sectional view schematically illustrating a light source unit and an optical unit according to an embodiment of the present disclosure;

[0028] Figure 3 is a cross-sectional view enlarging a portion of a light source unit according to a first embodiment of the present disclosure;

[0029] Figure 4 is a plan view schematically illustrating a pad according to a first embodiment of the present disclosure;

[0030] Figure 5Aand Figure 5B is a plan view schematically illustrating another pad according to the first embodiment of the present disclosure;

[0031] Figures 6 to 11 is a cross-sectional view in which a part of a light source unit according to a second embodiment of the present disclosure is enlarged; and

[0032] Fig.12 is a cross-sectional view enlarging a part of a light source unit according to a third embodiment of the present disclosure. DETAILED DESCRIPTION

[0033] Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. The same reference numerals may be used throughout the drawings to refer to the same or similar parts.

[0034] Figure 1 is an exploded perspective view illustrating a display device according to an embodiment of the present disclosure.

[0035] Reference Figure 1 , the display device 100 may include a display panel 110 and a backlight unit 120 providing light to the display panel 110. The backlight unit 120 may be a backlight structure including a backlight circuit and may be referred to as the backlight unit 120.

[0036] For the convenience of explanation, the directions in the drawings are defined as follows: if the display surface of the display panel 110 faces forward, the backlight unit 120 is located behind the display panel 110 .

[0037] Explain these components in more detail.

[0038] The display panel 110 may use a display panel selected from the group consisting of a liquid crystal display (LCD) panel, a plasma display panel (PDP) panel, a field emission display (FED) panel, an electroluminescent display (ELD) panel, and an organic light emitting diode (OLED) panel.

[0039] For convenience of explanation, an LCD device is explained by way of example, which transmits light emitted from the backlight unit 120 to the display panel 110 by controlling an electric field applied to a liquid crystal layer of the display panel 110 and changing arrangement of liquid crystal molecules, thereby displaying an image.

[0040] The display panel 110 is a part that plays a key role in image display, and may include a first substrate 112 and a second substrate 114 that are attached to each other with a liquid crystal layer interposed therebetween.

[0041] Assuming that the display panel is an active matrix panel, although not shown in detail in the figure, a plurality of pixels can be defined (for example, arranged at the intersection) by a plurality of gate lines and a plurality of data lines crossing on the inner surface of a first substrate 112 (referred to as a lower substrate or an array substrate), and a thin film transistor (TFT) can be located at each intersection and connected to a pixel electrode formed in each pixel.

[0042] On the inner surface of the second substrate 114, which is referred to as an upper substrate or a color filter substrate, red (R), green (G), and blue (B) color filters corresponding to respective pixels and a black matrix surrounding the color filters and blocking non-display elements such as gate lines, data lines, and thin film transistors may be formed. A transparent common electrode may be provided to cover the color filters and the black matrix.

[0043] Although not clearly shown in the figure, the upper orientation layer and the lower orientation layer can be inserted at the boundary between the two substrates 112, 114 and the liquid crystal layer of the display panel 110 to prevent leakage of the liquid crystal molecules filled between the upper orientation layer and the lower orientation layer, and a seal pattern can be formed along the edges of the two substrates 112, 114.

[0044] Upper and lower polarizing plates (not shown) may be attached to the first and second substrates 112 and 114 , respectively.

[0045] The printed circuit board 117 may be connected to an edge of the display panel 110 through a connection member 116 such as a flexible circuit board or a tape carrier package (TCP).

[0046] When the thin film transistor selected by the gate line is turned on by the on / off signal transmitted to the thin film transistor of the gate line, the image signal of the data line is transmitted to the corresponding pixel electrode, and through the electric field generated between the pixel electrode and the common electrode, the orientation direction of the liquid crystal molecules changes, resulting in a difference in transmittance.

[0047] In the display device 100 according to the embodiment of the present disclosure, in order to display the difference in light transmittance generated by the display panel 110 to the outside, the backlight unit 120 providing light at the rear of the display panel 110 is provided.

[0048] High-brightness planar light implemented by the backlight unit 120 is provided to the display panel 110 , and thus the display panel 110 displays an image.

[0049] The backlight unit may include a light source unit 200 and an optical unit 230 located on the light source unit 200. The light source unit 200 may be a light source structure and may be referred to as a light source structure. The optical unit 230 may be an optical structure and may be referred to as an optical structure.

[0050] The light source unit 200 may include a plate-shaped glass PCB 220 and a plurality of light sources 210 mounted on the glass PCB 220 at predetermined or selected intervals. In another embodiment, the PCB 220 is made of any acceptable material that does not include glass. In one embodiment, the glass used for the PCB may be of the type of fiberglass. Therefore, the fiberglass PCB is considered to be a glass PCB within the context of the present application, and similarly, a fiberglass-based substrate is considered to be a glass substrate. In one embodiment, the glass used for the PCB is completely transparent glass, and the glass PCB is completely transparent except where there are copper lines. Therefore, the glass PCB and the glass substrate may be composed of transparent glass through which light can pass. Transparent glass PCBs are known in the art, and for this embodiment, any commercially available transparent glass PCB is acceptable. Other types of glass-based substrates other than fiberglass and transparent glass may also be used as the glass substrate.

[0051] Each light source 210 may be formed of a light emitting diode (LED). As the LED of the light source 210, a mini LED having a size of hundreds of micrometers or a micro LED (μLED) having a size of tens of micrometers may be used.

[0052] In order to improve the luminous efficiency and brightness of the LED 210 as the light source according to an embodiment of the present disclosure, a blue LED may be used, and the LED 210 may use a blue LED including a multi-quantum well layer emitting blue light with good luminous efficiency and brightness.

[0053] The optical unit 230 located on the light source unit 200 may serve to diffuse and guide incident light from the light source unit 200 to the entire backlight unit 120 , and may serve to provide uniformly processed white plane light to the display panel 110 .

[0054] Therefore, in the display device 100 according to the embodiment of the present disclosure, uniformly processed white planar light may be provided to the display panel 110 .

[0055] Figure 2is a cross-sectional view schematically illustrating a light source unit and an optical unit according to an embodiment of the present disclosure.

[0056] Reference Figure 2 , the optical unit 230 may be located on the light source unit 200 in the display area AA. The plurality of LEDs 210 of the light source unit 200 may be mounted on a plate-shaped glass PCB 220 using a surface mount technology (SMT: Surface Mount Technology).

[0057] The glass PCB 220 may include a plurality of circuit layers 223 , 225 and a plurality of insulating layers 227 a , 227 b on a substrate 221 .

[0058] In more detail, the glass PCB 220 may include a substrate 221 formed of glass. The substrate 221 may be used to install and support the circuit layers 223 and 225 and the insulating layers 227 a and 227 b located on the substrate 221 .

[0059] On the substrate 221, a first wiring layer 223 including a first wiring pattern 223a and a second wiring pattern 223b formed by patterning a conductive material may be formed. The first wiring layer 223 may be configured as a double-layer structure having a copper (Cu) layer stacked on a molybdenum-titanium (MoTi) alloy layer.

[0060] In this regard, since a plurality of LEDs 210 are mounted on the glass PCB 220, the signal processing speed of the line patterns 223a, 223b, 225a, and 225b formed at the glass PCB 220 needs to benefit from being fast. Therefore, the line patterns 223a, 223b, 225a, and 225b are formed using a copper (Cu) layer having excellent specific resistance and electron mobility, but the copper (Cu) has poor adhesion to the substrate 221 and has a problem of peeling or floating off.

[0061] Therefore, in one embodiment, it is recommended to configure the structure of the line patterns 223a, 223b, 225a, and 225b to have a double layer consisting of a copper (Cu) layer and a barrier layer additionally included under the copper (Cu) layer to improve the adhesion between the glass substrate and the line patterns 223a, 223b, 225a, and 225b. The barrier layer may be molybdenum (Mo), titanium (Ti), molybdenum alloy (Moalloy), or titanium alloy (Ti alloy).

[0062] It is explained by way of example that the glass PCB 220 according to an embodiment of the present disclosure has a double-layer structure configured with a copper (Cu) layer and a barrier layer, wherein the copper (Cu) layer is stacked on a molybdenum-titanium (MoTi) alloy layer.

[0063] The first insulating layer 227a may be located on the first line layer 223. The first insulating layer 227a may include a first contact hole 228a exposing the first line pattern 223a.

[0064] The second wiring layer 225 including the third wiring pattern 225a and the fourth wiring pattern 225b may be located on the first insulating layer 227a including the first contact hole 228a. The second wiring layer 225 may be configured as a double layer having a copper (Cu) layer and a barrier layer, wherein the copper (Cu) layer is stacked on the molybdenum-titanium (MoTi) alloy layer.

[0065] The third line pattern 225 a may contact the first line pattern 223 a exposed through the first contact hole 228 a .

[0066] The second insulating layer 227b may be located on the second wiring layer 225. The second insulating layer 227b may include a second contact hole 228b and a third contact hole 228c that expose the third wiring pattern 225a and the fourth wiring pattern 225b, respectively. Portions of the third wiring pattern 225a and the fourth wiring pattern 225b exposed through the second contact hole 228b and the third contact hole 228c may be a first pad 229a and a second pad 229b, respectively.

[0067] The first insulating layer 227a and the second insulating layer 227b may be formed of a material having excellent electrical insulation. The first insulating layer 227a and the second insulating layer 227b may be formed by depositing oxide or nitride or by depositing or spin coating a resin such as polyimide.

[0068] The first pad 229a and the second pad 229b exposed through the second contact hole 228b and the third contact hole 228c of the second insulating layer 227b can be soldered (soldering) to the cathode and anode (not shown) of the LED 210 respectively through a solder resist formed by an organic solder preserve (OSP), and the LED 210 can be surface-mounted on the glass PCB 220.

[0069] A cover layer 224 may be formed around the LED 210 electrically connected to the first and second pads 229a and 229b under the second insulating layer 227b. The cover layer 224 may preferably be formed of white photo solder resist ink (PSR) having high reflection efficiency to serve as a brightness reflector of the LED 210.

[0070] Therefore, the cover layer 224 may reflect light emitted from the LED 210 forward and improve brightness.

[0071] The glass PCB 220 may not have the first and second insulating layers 227a and 227b under the LED 210, so that the glass PCB 220 may include the heat dissipation groove A with air. Due to the heat dissipation groove A, high temperature heat generated from the LED 210 may be easily dissipated to the outside.

[0072] In addition, it is preferred that the line patterns 223a, 223b, 225a, and 225b do not exist in the heat dissipation groove A. This is because the line patterns 223a, 223b, 225a, and 225b in the heat dissipation groove A may overflow due to the thermal expansion of the line patterns 223a, 223b, 225a, and 225b in the sealed heat dissipation groove A caused by the soldering temperature in the process of mounting the LED 210 on the glass PCB 220, and a short-circuit defect of the line patterns 223a, 223b, 225a, and 225b may occur.

[0073] The third line pattern 225a may extend over the non-display area NA of the glass PCB 220 and may form an external contact pad 241 to be connected to an external driving circuit (not shown). On the external contact pad 241, a connector 240 may be mounted through the solder resist 213.

[0074] The connector 240 mounted on the glass PCB 220 can be connected to an external driving circuit (not shown) such as an LED driving circuit via an FPC or FFC (Flexible Flat Cable), and can provide power from the LED driving circuit to each LED 210 via the wiring layers 223 and 225.

[0075] In the light source unit 200 according to an embodiment of the present disclosure, the line patterns 223a, 223b, 225a, and 225b included in the glass PCB 220 may be formed into a first line layer 223 and a second line layer 225. Therefore, a voltage drop phenomenon that may be caused by a copper (Cu) layer formed only with a very thin thickness may be prevented because the substrate 221 of the glass PCB 220 is formed of glass.

[0076] In other words, on a prior art circuit board using a substrate formed of a synthetic resin or an insulating material, the copper (Cu) layer of the circuit layer can be formed by an electroless plating method, and thus the copper (Cu) layer can have a thickness of about 5 μm to about 7 μm. However, on the glass PCB 220 of the embodiment of the present disclosure formed of glass, the copper (Cu) layer of the circuit layers 223 and 225 can be formed only by a sputtering method and can have a thickness of up to about 1 μm.

[0077] Therefore, the copper (Cu) layer formed on the glass PCB 220 may have excellent specific resistance and electron mobility, but because the copper (Cu) layer may be formed with a very thin thickness, a voltage drop phenomenon may occur. In the display device 100 of the embodiment of the present disclosure, a plurality of line layers 223 and 225 each including a copper (Cu) layer may be formed, thereby solving the above problem.

[0078] The resin layer 250 may be located on the glass PCB 220 to cover the glass PCB 220. The resin layer 250 may be coated on the glass PCB 220 with a thickness greater than that of the light source unit 200 and may cover all the LEDs 210 mounted on the glass PCB 220.

[0079] The resin layer 250 may serve to fix and protect the LED 210 , and to support the optical unit 230 located on the light source unit 200 .

[0080] Therefore, an optical gap or an air gap may be defined (eg, may exist) between the light source unit 200 and the optical unit 230 .

[0081] The optical gap or air gap may be a region (or space) where the light emitted from two or three adjacent LEDs 210 overlaps or mixes with each other. Without obtaining the optical gap or air gap, a dark portion where the light does not overlap or mix with each other may be generated between the adjacent LEDs 210.

[0082] The optical unit 230 supported by the resin layer 250 and located above the light source unit 200 and spaced apart from the light source unit 200 at a predetermined or selected interval may include a diffusion plate 231, a fluorescent sheet 239, a light collecting portion 233, a light diffusion portion 235, and a composite optical portion 237 positioned sequentially.

[0083] The diffusion plate 231 may serve to diffuse light emitted from the LED 210 of the light source unit 200 and provide uniform planar light to the display panel 110 .

[0084] A reflection pattern sheet (not shown) may be located under the diffusion plate 231. The reflection pattern sheet may include a plurality of reflection patterns located corresponding to the plurality of LEDs 210, respectively.

[0085] The reflective pattern can be used to reflect a portion of the light emitted upward from the corresponding LED 210 thereunder and distribute it laterally, while another portion of the light can be transmitted through the reflective pattern and propagate upward. Therefore, most of the emitted light can be prevented from entering the display panel 110 upward.

[0086] Therefore, hot spots caused by light entering vertically in an upward direction can be prevented.

[0087] The fluorescent sheet 239 may be located on the diffusion plate 231. The fluorescent sheet 239 may include at least one fluorescent substance that absorbs the first color light generated by the LED 210 and generates at least one color light different from the first color.

[0088] In the case of using the fluorescent sheet 239 , the light of the first color generated by the LED 210 and the light of the color generated by the fluorescent sheet 239 may be mixed, and white light may be finally generated and provided to the display panel 110 .

[0089] In this regard, in order to improve the luminous efficiency and brightness of the LED 210 according to the embodiment of the present disclosure, the LED 210 may use a blue LED including a multi-quantum well layer that emits blue light with good luminous efficiency and brightness. Therefore, in the case of generating blue light as the first color light from the LED 210, the fluorescent sheet 239 may absorb a portion of the blue light to generate yellow light as the second color light.

[0090] The LEDs 210 may respectively emit red (R), green (G), and blue (B) light, and by simultaneously turning on the LEDs 210 respectively emitting red (R), green (G), and blue (B) light, white light may be obtained through color mixing.

[0091] Alternatively, the LED 210 may use a white LED including a blue LED chip and cerium-doped yttrium aluminum garnet (YAG:Ce), ie, a yellow fluorescent substance, and directly emit white light. In this case, the fluorescent sheet 239 may be removed.

[0092] The light-condensing portion 233 may include a support layer 233 a and a lens layer 233 b located on the support layer 233 a and condensing light.

[0093] The lens layer 233b may be formed of a transparent acrylic-based resin. The lens layer 233b may include a plurality of prisms each having a stripe shape and adjacently arranged along the length direction of the optical unit 230, forming a mountain and valley repeating structure, and protruding from the support layer 233a.

[0094] The light diffusion portion 235 may be located on the light collection portion 233. The light diffusion portion 235 may diffuse the light output from the light collection portion 233 to uniformly distribute the light over a large area.

[0095] The light diffusion part 235 may include a diffusion layer. The diffusion layer may be configured to include a light diffusion component such as beads, or to be configured to have a fine pattern formed on the bottom surface of the diffusion layer without beads.

[0096] Therefore, the diffusion layer may serve to diffuse light by refracting and scattering incident light, and to convert non-uniform light passing through the light-condensing portion 233 into uniform light and output the uniform light.

[0097] The composite optical part 237 may be configured to have at least two light-collecting parts coupled to each other in an integrated form, and the prisms of the at least two light-collecting parts may be arranged to cross each other in the length direction. Alternatively, the composite optical part 237 may be configured with a polygonal prism having a cross section different from a triangular cross section, a microlens pattern, a cylindrical lens, an embossed pattern, or a combination thereof.

[0098] In addition, even though not shown in the drawings, the optical unit 230 may include a dichroic layer and a cover conversion layer, which may be used to process light emitted from the LED 210 of the light source unit 200 into white light with improved color purity.

[0099] The optical unit 230 may be attached to the bottom surface of the display panel 110 by a lamination process using a transparent bonding member (not shown). The transparent bonding member may be an optically clear adhesive (OCA), an optically clear resin (OCR), a porous OCA (Porous Optically Clear Adhesive), or a porous OCR (Porous Optically Clear Resin).

[0100] In the display device 100 according to an embodiment of the present disclosure, it is characterized in that the LED 210 of the light source unit 200 is mounted on the glass PCB 220 .

[0101] Therefore, in the display device 100 according to an embodiment of the present disclosure, since the substrate 221 of the glass PCB 220 of the light source unit 200 can be formed of glass, thermal conductivity can be improved and flatness can be greatly improved compared to a related art circuit board using a substrate formed of a synthetic resin or an insulating material.

[0102] Therefore, high temperature heat generated from the LED 210 can be quickly dissipated to the outside, and failure of the LED 210 or shortening of the life of the LED 210 can be prevented. In addition, poor bonding of the line patterns 223a, 223b, 225a, and 225b formed on the glass PCB 220 can be prevented.

[0103] Finally, the production cost of the glass PCB 220 may be reduced, and the efficiency of the manufacturing process of the glass PCB 220 may be improved.

[0104] Particularly, in the display device 100 according to the embodiment of the present disclosure, in addition to the above advantages, detachment of the LED 210 and the connector 240 mounted on the glass PCB 220 of the light source unit 200 and problems caused by the detachment may be prevented.

[0105] <First Embodiment>

[0106] Figure 3 is a cross-sectional view enlarging a part of the light source unit according to the first embodiment of the present disclosure, Figure 4 , Figure 5A and Figure 5B is a plan view schematically illustrating a pad according to a first embodiment of the present disclosure.

[0107] Reference Figure 3 , on glass PCB( Figure 2 220), the third line pattern 225a and the fourth line pattern 225b may be located on the substrate ( Figure 2 The first insulating layer 227a on the third wiring pattern 221 of the present invention may be provided. The second insulating layer 227b may be provided on the third wiring pattern 225a and the fourth wiring pattern 225b. The second insulating layer 227b may include a second contact hole 228b and a third contact hole 228c exposing the first pad 229a and the second pad 229b, respectively, and the third wiring pattern 225a and the fourth wiring pattern 225b may include a first pad 229a and a second pad 229b located at the ends of the third wiring pattern 225a and the fourth wiring pattern 225b facing each other, respectively.

[0108] The first and second pads 229a and 229b exposed through the second and third contact holes 228b and 228c and the LED 210 may be soldered to each other using the solder resist 213, and the LED 210 may be mounted on a glass PCB ( Figure 2 220).

[0109] The solder resist 213 may be formed of a tin (Sn)-based material. More specifically, the solder resist 213 may include tin (Sn) as a main component and additionally silver (Ag) and / or copper (Cu).

[0110] In the display device 100 according to the first embodiment of the present disclosure, the third line pattern 225a and the fourth line pattern 225b may each have a double-layer structure of molybdenum-titanium (MoTi) alloy layers 225a-1, 225b-1 and copper (Cu) layers 225a-2, 225b-2 stacked together. The first pad 229a and the second pad 229b located at the end of the third line pattern 225a and the fourth line pattern 225b may each have a three-layer structure of molybdenum-titanium (MoTi) alloy layers 229a-1, 229b-1 and copper (Cu) layers 229a-2, 229b-2 and an additional diffusion barrier pattern 300 located thereon.

[0111] In other words, refer to Figure 4 The first and second pads 229a and 229b may further include respective diffusion barrier patterns 300 located on the copper (Cu) layers 229a-2 and 229b-2 and exposing portions of the copper (Cu) layers 229a-2 and 229b-2.

[0112] The diffusion barrier pattern 300 may be configured in a lattice shape and formed of a molybdenum-titanium (MoTi) alloy, but is not limited thereto.

[0113] Therefore, in the display device ( Figure 1 100), the LED 210 mounted on the glass PCB can be prevented from being detached.

[0114] In more detail, the pads 229a, 229b include copper (Cu) layers 229a-2, 229b-2, and the solder resist 213 may be formed of a tin (Sn)-based material. In this case, when soldering is performed on the pads 229a, 229b using the solder resist 213, an intermetallic compound (IMC) having an ε-phase Cu3Sn and an η-phase Cu6Sn5 conformation is formed at the interface between the copper (Cu) layers 229a-2, 229b-2 and the solder resist 213.

[0115] Voids are formed in the IMC. These voids are Kirkendall voids formed by the difference in diffusion speed of atoms, and the Kirkendall voids grow in a mutually connected manner.

[0116] Therefore, at the soldering region as the bonding portion where the Kirkendall void is formed between the copper (Cu) layers 229 a - 2 , 229 b - 2 and the solder resist 213 , the reliability of mechanical impact characteristics or the like is seriously affected.

[0117] Therefore, the LED 210 can be easily separated from the glass PCB even by a very small external force.

[0118] Therefore, it is preferable to prevent the formation of IMC between the pads 229a, 229b and the solder resist 213. Figure 2 200), a diffusion barrier pattern 300 formed of a molybdenum-titanium (MoTi) alloy may be formed on a glass PCB ( Figure 2 On the copper (Cu) layers 229a-2, 229b-2 of the pads 229a, 229b of 220).

[0119] Molybdenum-titanium (MoTi) alloy can re-form a bonding surface with an electrode formed of copper (Cu). In particular, molybdenum-titanium (MoTi) alloy can suppress the occurrence of voids at high temperatures and improve bonding strength.

[0120] In other words, the diffusion barrier pattern 300 made of the molybdenum-titanium (MoTi) alloy can be used to suppress the diffusion of copper (Cu) from the copper (Cu) layers 229a-2, 229b-2 to the solder resist 213. Therefore, the diffusion barrier pattern 300 made of the molybdenum-titanium (MoTi) alloy can suppress the mutual diffusion between the copper (Cu) layers 229a-2, 229b-2 and the solder resist 213, thereby suppressing the growth of IMC of Cu3Sn or Cu6Sn5. Therefore, the occurrence of Kirkendall voids can be reduced.

[0121] As a result, the pads 229 a , 229 b and the solder resist 213 can have excellent electrical contact characteristics and high reliability due to reduced occurrence of Kirkendall voids.

[0122] Therefore, in the display device ( Figure 1 100), even if the pads 229a, 229b include the copper (Cu) layers 229a-2, 229b-2, it is possible to prevent the mounting on the glass PCB ( Figure 2 220) and detachment of LED 210 on the LED 210.

[0123] In the first embodiment of the present disclosure, the molybdenum-titanium (MoTi) alloy layer extending from the diffusion barrier pattern 300 is exemplified as being located on the copper (Cu) layers 225a-2, 225b-2 of the third and fourth wiring patterns 225a and 225b. However, the molybdenum-titanium (MoTi) alloy layer located on the copper (Cu) layers 225a-2, 225b-2 of the third and fourth wiring patterns 225a and 225b may be removed during the process of forming the diffusion barrier pattern 300 of the first and second pads 229a and 229b.

[0124] In other words, if Figure 4As shown, the first pad 229a and the second pad 229b may further include a diffusion barrier pattern 300 located on the copper (Cu) layers 229a-2 and 229b-2 and exposing portions of the copper (Cu) layers 229a-2 and 229a-2.

[0125] The diffusion barrier pattern 300 may have a lattice shape and be formed of a molybdenum-titanium (MoTi) alloy, but is not limited thereto.

[0126] Apart from Figure 4 The grid shape shown in the figure, the light source unit ( Figure 2 Glass PCB (200) Figure 2 The diffusion barrier pattern 300 at 220) may be formed as a plurality of strip-shaped portions spaced apart from each other at predetermined or selected intervals, such as Figure 5A As shown, or a plurality of strip-shaped portions separated from each other at predetermined or selected intervals and each having a plurality of bends, as Figure 5B It should be understood that "bend" includes the term Figure 5B The shape of the diffusion barrier pattern 300 shown in the figure has the meaning of wavy, S-shaped, curved, or other similar descriptors. With respect to the page, the diffusion barrier pattern 300 includes a horizontal portion (extending from the left side to the right side) and a vertical portion (extending up and down). The horizontal portions offset each other in the vertical direction and are interconnected with each other through the vertical portions at the respective ends of the horizontal portions. The shape (e.g., curvature) of the diffusion barrier pattern 300 along the horizontal direction can be regular (e.g., periodic) or irregular (e.g., non-periodic).

[0127] <Second Embodiment>

[0128] Figures 6 to 11 This is an enlarged cross-sectional view of a part of a light source unit according to a second embodiment of the present disclosure.

[0129] Reference Figures 6 to 11 , on glass PCB( Figure 2 220), the third line pattern 225a and the fourth line pattern 225b may be located on the substrate ( Figure 2 The first insulating layer 227a on the third wiring pattern 221 of the present invention may be provided. The second insulating layer 227b may be provided on the third wiring pattern 225a and the fourth wiring pattern 225b. The second insulating layer 227b may include a second contact hole 228b and a third contact hole 228c exposing the first pad 229a and the second pad 229b, respectively, and the third wiring pattern 225a and the fourth wiring pattern 225b may include a first pad 229a and a second pad 229b located at the ends of the third wiring pattern 225a and the fourth wiring pattern 225b facing each other, respectively.

[0130] The first and second pads 229a and 229b exposed through the second and third contact holes 228b and 228c and the LED 210 may be soldered to each other using the solder resist 213, and the LED 210 may be mounted on a glass PCB ( Figure 2 220).

[0131] The solder resist 213 may be formed of a tin (Sn)-based material. More specifically, the solder resist 213 may include tin (Sn) as a main component and additionally silver (Ag) and / or copper (Cu).

[0132] In the display device 100 according to the second embodiment of the present disclosure, as Figure 6 As shown, the first pad 229a and the second pad 229b may have a three-layer structure of a molybdenum-titanium (MoTi) alloy layer 229a-1, 229b-1 and a copper (Cu) layer 229a-2, 229b-2 and an additional diffusion barrier pattern 300 located thereon, and the molybdenum-titanium (MoTi) alloy layer 229a-1, 229b-1 and the copper (Cu) layer 229a-2, 229b-2 may be patterned simultaneously with the diffusion barrier pattern 300 to expose the second insulating layer 227b thereunder.

[0133] In other words, the molybdenum-titanium (MoTi) alloy layers 229 a - 1 and 229 b - 1 and the copper (Cu) layers 229 a - 2 and 229 b - 2 and the diffusion barrier pattern 300 may all have a lattice shape.

[0134] When the molybdenum-titanium (MoTi) alloy layers 229a-1, 229b-1 and the copper (Cu) layers 229a-2, 229b-2 together with the diffusion barrier pattern 300 are configured to expose the second insulating layer 227b, the contact area between the pads 229a, 229b and the solder resist 213 can be maximized, and the pads 229a, 229b and the solder resist 213 can be fixed more firmly.

[0135] Or, if Figure 7 As shown, the third line pattern 225a and the fourth line pattern 225b may have a double-layer structure of molybdenum-titanium (MoTi) alloy layers 225a-1, 225b-1 and copper (Cu) layers 225a-2, 225b-2 stacked together. The first pad 229a and the second pad 229b may have a first diffusion barrier pattern 300-1 and a second diffusion barrier pattern 300-2 located on the double layer of the molybdenum-titanium (MoTi) alloy layers 229a-1, 229b-1 and the copper (Cu) layers 229a-2, 229b-2.

[0136] The first diffusion barrier pattern 300-1 may be formed of a molybdenum-titanium (MoTi) alloy, and the second diffusion barrier pattern 300-2 may be formed of copper (Cu). The first diffusion barrier pattern 300-1 and the second diffusion barrier pattern 300-2 may be simultaneously patterned to expose the copper (Cu) layers 225a-2, 225b-2 of the third and fourth line patterns 225a and 225b.

[0137] like Figure 8 As shown, the molybdenum-titanium (MoTi) alloy layers 229a-1, 229b-1 and the copper (Cu) layers 229a-2 and 229b-2 may also be patterned simultaneously with the first diffusion barrier pattern 300-1 and the second diffusion barrier pattern 300-2 to expose the first insulating layer 227a.

[0138] Therefore, the formation of IMC between the pads 229a, 229b and the solder resist 213 can be suppressed, and the occurrence of Kirkendall voids can be reduced. Therefore, the pads 229a, 229b and the solder resist 213 can have excellent electrical contact characteristics and high reliability, and the contact area between the pads 229a, 229b and the solder resist 213 can be maximized.

[0139] In this regard, by the second diffusion barrier pattern 300 - 2 formed of copper (Cu), the contact area between the pads 229 a , 229 b and the solder resist 213 may be maximized or increased, and thus the pads 229 a , 229 b and the solder resist 213 may be more securely fixed.

[0140] In other words, the solder resist 213 may first contact and adhere to the copper (Cu) layers 225a-2, 225b-2 of the third and fourth line patterns 225a and 225b exposed by the first and second diffusion barrier patterns 300-1 and 300-2, and then contact and adhere to the side surfaces of the first and second diffusion barrier patterns 300-1 and 300-2. Therefore, the contact area between the pads 229a, 229b and the solder resist 213 may be maximized or increased.

[0141] Therefore, the pads 229a, 229b and the solder resist 213 can be fixed more firmly, and even if the pads 229a, 229b include the copper (Cu) layers 229a-2 and 229b-2, the solder resist 213 can be prevented from being mounted on the glass PCB ( Figure 2 220) on which LED 210 is detached.

[0142] Alternatively, in addition to simultaneously patterning the first diffusion barrier pattern 300-1 and the second diffusion barrier pattern 300-2 to expose the copper (Cu) layers 225a-2 and 225b-2 of the third line pattern 225a and the fourth line pattern 225b, Figure 7 In addition to the configuration of the third diffusion barrier pattern 300-3, the third diffusion barrier pattern 300-3 may be formed on the first diffusion barrier pattern 300-1 and the second diffusion barrier pattern 300-2. Fig. 9 The third diffusion barrier pattern 300 - 3 may be formed of a molybdenum-titanium (MoTi) alloy.

[0143] By forming the third diffusion barrier pattern 300-3 of molybdenum titanium (MoTi) on the second diffusion barrier pattern 300-2 of copper (Cu), formation of IMC even between the second diffusion barrier pattern 300-2 and the solder resist 213 may be suppressed and occurrence of Kirkendall voids in this region may be reduced.

[0144] Or, if Fig.10 As shown, the molybdenum-titanium (MoTi) alloy layers 229a-1, 229b-1 and the copper (Cu) layers 229a-2, 229b-2 may also be patterned simultaneously with the first to third diffusion barrier patterns 300-1, 300-2, 300-3 to expose the first insulating layer 227a.

[0145] Or, if Fig.11 As shown, the third line pattern 225a and the fourth line pattern 225b may have a double-layer structure of molybdenum-titanium (MoTi) alloy layers 225a-1, 225b-1 and copper (Cu) layers 225a-2, 225b-2 stacked together. The first pad 229a and the second pad 229b may have a first diffusion barrier pattern 300-1 and a second diffusion barrier pattern 300-2 located on the double layer of molybdenum-titanium (MoTi) alloy layers 229a-1, 229b-1 and copper (Cu) layers 229a-2, 229b-2. In this case, although the first diffusion barrier pattern 300-1 may be patterned, the second diffusion barrier pattern 300-2 may not be patterned.

[0146] In the case where the second diffusion barrier pattern 300-2 is not patterned, the second diffusion barrier pattern 300-2 is completely adhered to the copper (Cu) layers 229a-2, 229b-2 of the pads 229a, 229b exposed by the patterned first diffusion barrier pattern 300-1, and the glass PCB ( Figure 2 The adhesion between the substrate 220) and the pads 229a, 229b can be further improved.

[0147] In addition, the thickness of the copper (Cu) layer can be ensured by the unpatterned second diffusion barrier pattern 300-2 and the copper (Cu) layers 229a-2 and 229b-2 of the pads 229a and 229b, and the voltage drop phenomenon caused by the thin thickness of the copper (Cu) layer can be prevented. As described above, in the display device ( Figure 1 100), the light source unit ( Figure 2 200) PCB can be made of glass PCB ( Figure 2 Therefore, compared with a related art circuit board using a substrate formed of a synthetic resin or an insulating material, thermal conductivity can be improved and flatness can be greatly improved.

[0148] Therefore, high temperature heat generated from the LED 210 can be quickly dissipated to the outside, and it is possible to prevent malfunction of the LED 210 or shortening of the life of the LED 210. In addition, poor bonding of the line patterns 225a, 225b formed on the glass PCB can be prevented.

[0149] Finally, the production cost of the glass PCB can be reduced, and the efficiency of the manufacturing process of the glass PCB can be improved.

[0150] In particular, in the display device according to the first and second embodiments of the present disclosure, since the diffusion barrier patterns 300-1, 300-2 can be formed on the pads 229a, 229b formed at the glass PCB of the light source unit, it is possible to prevent the IMC from being formed between the pads 229a, 229b and the solder resist 213. Therefore, the LED 210 can be stably mounted on the glass PCB, and problems caused by detachment of the LED 210 can be prevented.

[0151] <Third Embodiment>

[0152] Fig.12 is a cross-sectional view enlarging a part of a light source unit according to a third embodiment of the present disclosure.

[0153] Reference Fig.12 , the external contact pad 241 may be formed in the non-display area ( Figure 2 The connector 240 may be soldered to the external contact pad 241 through the solder resist 213.

[0154] The connector 240 may be electrically connected to an external driving circuit (not shown).

[0155] The solder resist 213 may be formed of a tin (Sn)-based material. More specifically, the solder resist 213 may include tin (Sn) as a main component and additionally silver (Ag) and / or copper (Cu).

[0156] In the display device ( Figure 1100), the external contact pad 241 may have a double-layer structure of a molybdenum-titanium (MoTi) alloy layer 241-1 and a copper (Cu) layer 241-2 stacked together, and the diffusion barrier pattern 300 may be further located on the copper (Cu) layer 241-2.

[0157] The diffusion barrier pattern 300 may be formed of a molybdenum-titanium (MoTi) alloy and patterned to expose the copper (Cu) layer 241 - 2 thereunder.

[0158] Therefore, in the display device according to the third embodiment of the present disclosure, the formation of the IMC between the external contact pad 241 and the solder resist 213 may be suppressed by the diffusion barrier pattern 300 , and the occurrence of Kirkendall voids may be reduced.

[0159] Therefore, the external contact pad 241 and the solder resist 213 can have excellent electrical contact characteristics and high reliability. Therefore, in the display device according to the third embodiment of the present disclosure, even if the external contact pad 241 includes the copper (Cu) layer 241-2, the connector 240 mounted on the glass PCB 220 can be prevented from being detached.

[0160] As described above, in the display device ( Figure 1 100), the light source unit ( Figure 2 The PCB of FIG. 200 may be formed of the glass PCB 220. Therefore, compared with a related art circuit board using a substrate of a synthetic resin or an insulating material, thermal conductivity may be improved and flatness may be greatly improved.

[0161] In particular, in the display device according to the third embodiment of the present disclosure, since the diffusion barrier pattern 300 can be formed on the external contact pad 241 formed at the glass PCB 220 of the light source unit, it is possible to prevent the IMC from being formed between the external contact pad 241 and the solder resist 213. Therefore, the connector 240 can be stably mounted on the glass PCB 220, and problems caused by detachment of the connector 240 can be prevented.

[0162] As described in the above embodiments, the light source unit of the display device may include a plurality of LEDs mounted on a glass PCB. Therefore, compared with a related art circuit board using a substrate formed of a synthetic resin or an insulating material, thermal conductivity may be improved and flatness may be greatly improved.

[0163] Therefore, the high temperature heat generated from the LED can be quickly dissipated to the outside, and the failure of the LED or the shortening of the life of the LED can be prevented. In addition, the poor bonding of the fine pattern formed on the glass PCB can be prevented.

[0164] Finally, the production cost of the glass PCB can be reduced, and the efficiency of the manufacturing process of the glass PCB can be improved.

[0165] In particular, since a diffusion barrier pattern can be formed on a pad formed at the glass PCB, an IMC can be prevented from being formed between the pad and the solder resist. Therefore, the LED can be stably mounted on the glass PCB, and problems caused by the falling off of the LED can be prevented.

[0166] It is obvious to those skilled in the art that various modifications and changes can be made to the present disclosure without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is intended to cover these modifications and changes of the present disclosure as long as they fall within the scope of the appended claims and their equivalents.

Claims

1. A light source unit for a display device, comprising: A printed circuit board, comprising: a pad located on a substrate and comprising a copper layer, and a first diffusion barrier pattern located on the pad and comprising a molybdenum alloy; and The LED is mounted on the pad through the solder resist. The first diffusion barrier pattern has a lattice shape and exposes the copper layer of the pad, or the first diffusion barrier pattern includes a plurality of stripe portions spaced apart from each other. 2 . The light source unit of claim 1 , wherein the first diffusion barrier pattern is made of a molybdenum-titanium alloy. The light source unit according to claim 1 , wherein the strip-shaped portion has a plurality of bent portions. 4 . The light source unit of claim 1 , further comprising a second diffusion barrier pattern on the first diffusion barrier pattern and made of copper. 5 . The light source unit of claim 4 , further comprising a third diffusion barrier pattern located on the second diffusion barrier pattern and made of a molybdenum-titanium alloy. 6 . The light source unit of claim 4 , wherein the first and second diffusion barrier patterns expose the copper layer of the pad. 7 . The light source unit of claim 4 , wherein the pad, the first diffusion barrier pattern, and the second diffusion barrier pattern expose an insulating layer under the pad. 8 . The light source unit of claim 1 , wherein the pad and the first diffusion barrier pattern expose an insulating layer under the pad. 9 . The light source unit of claim 1 , wherein the pad further comprises a molybdenum-titanium alloy layer under the copper layer.

10. The light source unit of claim 1, wherein another diffusion barrier pattern is located on an external contact pad including a copper layer on one side of the printed circuit board and comprises a molybdenum alloy, and Wherein a connector is mounted on the external contact pad via another solder resist.

11. The light source unit according to claim 1, wherein the printed circuit board is composed of glass.

12. The light source unit according to claim 11, wherein the glass for the printed circuit board is completely transparent glass.

13. The light source unit according to claim 1, wherein the substrate is composed of glass.

14. A display device, comprising: The light source unit comprises: Printed circuit boards; and a plurality of light emitting diodes mounted on the printed circuit board; an optical unit located on the light source unit; and a display panel located on the optical unit, wherein the printed circuit board comprises a pad, and a first diffusion barrier pattern, wherein the pad comprises a copper layer, and the first diffusion barrier pattern is made of a molybdenum-titanium alloy, wherein the light emitting diode is mounted on the pad via a solder resist, and The first diffusion barrier pattern has a lattice shape and exposes the copper layer of the pad, or the first diffusion barrier pattern includes a plurality of stripe portions spaced apart from each other. 15 . The display device of claim 14 , wherein the second diffusion barrier pattern is on the first diffusion barrier pattern and is made of copper. 16 . The display device of claim 15 , wherein the third diffusion barrier pattern is on the second diffusion barrier pattern and is made of a molybdenum-titanium alloy. 17 . The display device of claim 15 , wherein an optical gap or an air gap is provided between the light source unit and the optical unit.

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