Pad connection structure and transparent display device including same

Abstract

Provided are a pad connection structure and a transparent display device including same. The pad connection structure includes: a pad element including a base substrate and pads arranged on the base substrate; a circuit board disposed on the pads and including a wiring layer; a conductive structure electrically connecting the wiring layer and the pads; and a bonding structure attaching the circuit board to the pad element and including a trench that is open at one end.

Description

Pad connection structure and transparent display device including the same

[0001] The present invention relates to a pad connection structure and a transparent display device including the same. More specifically, the invention relates to a pad connection structure including a circuit board and pads, and a transparent display device including the same.

[0002] For example, it is applied to Light Emitting Diode (LED) display panels and is widely utilized in the fields of advertising videos and media art. As an eco-friendly component, LEDs provide high response speed and high-brightness color reproduction. Furthermore, brightness and color temperature can be controlled by adjusting the light output of red, green, and blue LEDs, and display devices can be manufactured in a compact size by assembling multiple LEDs into a single module or panel.

[0003] A transparent display device may include a transparent substrate and a plurality of LED elements arranged on the transparent substrate. Circuit wiring for driving the plurality of LED elements is arranged on the transparent substrate.

[0004] Connections between pads and circuit boards may be performed to supply signals to the above circuit wirings. The connection of the circuit board may involve high-temperature heat treatment, which may result in damage to structures due to heat and gas generation. In this case, mechanical and electrical defects may occur due to poor bonding of the circuit board, and the electrical signal characteristics to the circuit wirings and LED elements may also be degraded.

[0005] One objective of the present invention is to provide a pad connection structure having improved thermal and mechanical stability.

[0006] One objective of the present invention is to provide a transparent display device having improved thermal and mechanical stability.

[0007] 1. A pad element comprising a base substrate and pads arranged on the base substrate; a circuit board disposed on the pads and comprising a wiring layer; a conductive structure electrically connecting the wiring layer and the pads; and a bonding structure that attaches the circuit board to the pad element and includes a trench with one end open.

[0008] 2. A pad connection structure in which, in the above 1, the other end opposite to the one end of the trench is closed.

[0009] 3. A pad connection structure in which, in the above 2, the pads are exposed from the bonding structure through the trench.

[0010] 4. A pad connection structure according to 3, wherein the pads are arranged in a second direction parallel to the upper surface of the base substrate to define a pad row, and a plurality of pad rows are arranged along a first direction parallel to the base substrate and intersecting the second direction.

[0011] 5. A pad connection structure according to 4, wherein the trench is formed corresponding to each of the pad rows, and the joining structure comprises blocking portions separating the trenches, and a merging portion that closes the other ends of the trenches and connects the blocking portions.

[0012] 6. A pad connection structure according to 1 above, wherein one end of the trench has a reduced width.

[0013] 7. A pad connection structure according to 1 above, wherein one end of the trench has an extended width.

[0014] 8. A pad connection structure according to 1 above, wherein one end of the circuit board does not overlap with one end of the bonding structure, and an opening is formed between the one end of the circuit board and the pad element that communicates with the open one end of the trench.

[0015] 9. The pad connection structure according to 1 above, wherein the circuit board comprises: a core layer; a first wiring layer disposed on the upper surface of the core layer; a second wiring layer disposed on the lower surface of the core layer; a through hole penetrating the core layer; and a wiring connection portion formed on the side wall of the through hole to connect the first wiring layer and the second wiring layer.

[0016] 10. In the above 9, the conductive structure is a pad connecting structure that extends from the upper surface of each of the pads and is inserted into the through hole.

[0017] 11. In the above 10, the conductive structure is a pad connection structure that contacts the wiring connection portion within the through hole.

[0018] 12. In the above 10, the conductive structure is a pad connection structure comprising solder pillars.

[0019] 13. In the above 1, the pad element further includes circuit wiring connected to each of the pads, and

[0020] A pad connection structure in which one end of the above trench is open toward the extension direction of the circuit wiring from the pads.

[0021] 14. A pad connection structure according to 1, wherein the pads each comprise a metal pattern and a capping layer formed on the surface of the metal pattern.

[0022] 15. A transparent display device comprising: a pad connection structure described above; circuit wiring connected to the pads of the pad connection structure; and light-emitting elements arranged on the base substrate and electrically connected to the circuit wiring.

[0023] 16. In the above 15, the base substrate includes a pad region where the pads are arranged and a device region where the light-emitting elements are arranged, and

[0024] A transparent display device in which one end of the trench of the pad connection structure is open toward the element area.

[0025] 17. In the above 15, further comprising a conductive intermediate structure connecting the circuit wiring and the light-emitting elements,

[0026] A transparent display device in which the above conductive mediating structure comprises the same material as the above conductive structure.

[0027] 18. A transparent display device according to 15, wherein the circuit wiring comprises a first driving wiring and a second driving wiring spaced apart from each other in parallel, and the light-emitting elements and the integrated circuit chips are arranged between the first driving wiring and the second driving wiring to form a row of light-emitting elements.

[0028] According to embodiments of the present invention, a bonding structure may be formed between an insulating layer covering a pad and a circuit board, and an opening may be formed at one end of the bonding structure. The opening may provide a passage for the discharge of outgas generated during a soldering or surface mount (SMT) process for connecting the circuit board and the pad.

[0029] Therefore, the formation of voids within the solder structure can be prevented during the above soldering or SMT process.

[0030] According to exemplary embodiments, the pad connection structure can be applied to the peripheral circuit structure of a transparent display device. Accordingly, the stability of the signal and power supplied to the light-emitting diode (LED) element and integrated circuit of the transparent display device is enhanced, and the operational stability / reliability of the transparent display device can be improved.

[0031] FIGS. 1 and FIGS. 2 are a schematic plan view and a cross-sectional view, respectively, showing a pad connection structure according to exemplary embodiments.

[0032] FIGS. 3 to 5 are schematic partial enlarged plan views showing pad connection structures according to some embodiments.

[0033] FIG. 6 is a schematic plan view showing a transparent display device according to exemplary embodiments.

[0034] FIG. 7 is a schematic partial enlarged plan view showing a circuit arrangement around a pixel according to exemplary embodiments.

[0035] FIG. 8 is a schematic cross-sectional view showing a transparent display device according to exemplary embodiments.

[0036] Embodiments of the present invention provide a pad connection structure comprising a pad, a circuit board, and a solder structure. Embodiments of the present invention provide a transparent display device comprising the pad connection structure.

[0037] Embodiments of the present invention will be described in more detail below with reference to the drawings. However, the following drawings attached to this specification are intended to illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the aforementioned description; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings.

[0038] The terms used in this application, such as "first," "second," "upper," "lower," "upper surface," and "lower surface," do not specify absolute positions but are used to distinguish different configurations or to differentiate relative positions between configurations.

[0039] The sizes of the configurations / structures depicted in the attached drawings may be exaggerated for convenience of explanation and are not limited to the sizes depicted in the drawings.

[0040] In the drawings below, the first direction and the second direction may refer to two directions that are parallel to the upper surface of the base substrate (100) and perpendicular to each other. For example, the first direction and the second direction may be the width direction and the length direction of the pad connection structure or the transparent display device, respectively. The third direction may refer to a direction that is perpendicular to the upper surface of the base substrate (100) and perpendicular to the first direction and the second direction. The third direction may be the thickness direction of the pad connection structure or the transparent display device.

[0041] FIGS. 1 and FIGS. 2 are a schematic plan view and a cross-sectional view, respectively, illustrating a pad connection structure according to exemplary embodiments. Specifically, FIGS. 2 is a cross-sectional view taken in the third direction along the II' line of FIGS. 1.

[0042] Referring to FIGS. 1 and 2, the pad connection structure may include a base substrate (100), a pad (130), a bonding structure (AL), and a circuit board (PCB).

[0043] The base substrate (100) may be a support substrate on which pads (130) are formed. As described below, the base substrate (100) may be provided as a support substrate on which light-emitting elements are arranged together with the pads (130).

[0044] The base substrate (100) is a polyester resin such as polyethylene terephthalate, polyethylene isophthalate, polyethylene naphthalate, polyethylene ether phthalate, polyethylene phthalate, polybutylene phthalate, polybutylene terephthalate; a cellulose resin such as diacetylcellulose, triacetylcellulose; a polycarbonate resin; an acrylic resin such as polyacrylate, polymethyl acrylate, polymethyl methacrylate, polyethyl acrylate, polyethyl methacrylate; a styrene resin such as polystyrene, acrylonitrile-styrene copolymer; a polyolefin resin such as polyethylene, polypropylene, cycloolefin, a polyolefin having a cyclo- or norbornene structure, or an ethylene-propylene copolymer; a vinyl chloride resin such as polyvinyl chloride, polyvinylidene chloride; an amide resin such as nylon, aromatic polyamide; A transparent resin substrate may be included, comprising imide-based resins such as polyimide and polyetherimide; polysulfone-based resins, polyethersulfone-based resins; sulfone-based resins; polyetheretherketone-based resins; polyphenylene sulfide-based resins; vinyl alcohol-based resins; vinylidene chloride-based resins; vinyl butyral-based resins; allylate-based resins; polyoxymethylene-based resins; epoxy-based resins; urethane-based or acrylicurethane-based resins; silicone-based resins, etc.

[0045] The base substrate (100) may include a glass substrate.

[0046] A pad (130) may be placed on a base substrate (100). According to exemplary embodiments, a plurality of pads (130) may be arranged in the second direction to form a row of pads. A plurality of the row of pads may be arranged in the first direction.

[0047] In some embodiments, the pads (130) may be attached to the upper surface of the base substrate (100) through a point adhesive layer (110). The pad (130) may include a metal pattern (121) and a capping layer (123).

[0048] A metal pattern (121) is placed on a base substrate (100) and may come into contact with a spot adhesive layer (110). A capping layer (123) may cover the surface of the metal pattern (121). For example, the capping layer (123) may cover the sides and the top surface of the metal pattern (121).

[0049] The metal pattern (121) may include silver (Ag), gold (Au), copper (Cu), aluminum (Al), platinum (Pt), palladium (Pd), niobium (Nb), vanadium (V), iron (Fe), manganese (Mn), cobalt (Co), nickel (Ni), zinc (Zn), molybdenum (Mo), calcium (Ca), or an alloy containing at least one of these. For example, the metal pattern (121) may include Cu.

[0050] The capping layer (123) may include a metal having relatively higher corrosion resistance and chemical stability than the metal pattern (121). For example, the capping layer (123) may include chromium (Cr), tin (Sn), titanium (Ti), tungsten (W), tantalum (Ta), etc. In one embodiment, the capping layer (123) may include tin (Sn).

[0051] In some embodiments, a metal foil may be attached to the upper surface of the base substrate (100) using a pressure-adhesive layer (110) to form a metal layer. The metal foil may include, for example, a copper foil.

[0052] In one embodiment, after forming a spot adhesive layer (110) on one side of the metal foil, the spot adhesive layer (110) can be attached to the upper surface of the base substrate (100). In one embodiment, the metal foil can be laminated with the base substrate (100) with the spot adhesive layer (110) in between.

[0053] Subsequently, the metal layer can be patterned through an etching process using a photosensitive dry film or a photoresist mask to form a metal pattern (121). A capping layer (123) can be formed by plating a metal such as tin (Sn) on the metal pattern (121). Accordingly, a pad (130) including the metal pattern (121) and the capping layer (123) can be formed.

[0054] Each of the pads (130) can be connected to a circuit wiring (140). The circuit wiring may have a conductive material and a laminated structure substantially identical or similar to the pad (130), and may be formed as a substantially integral member disposed in the same layer as the pad (130).

[0055] The pads (130) may include a driving pad (130a) and a data pad (130b). The driving pad (130a) may be connected to a first driving wire (142) or a second driving wire (144) (see FIG. 6). The data pad (130b) may be connected to a data wire (156) (see FIG. 6).

[0056] Pads (130) may be arranged on a pad region (PA) of a base substrate (100). According to exemplary embodiments, the base substrate (100) may include a device region (DA) (see FIG. 6) where light-emitting elements (180) are placed. Circuit wiring (140) extends from the device region (DA) to the pad region (PA) and may be connected to the pad (130).

[0057] A protective layer (160) covering the pads (130) may be formed on the base substrate (100) or the adhesive layer (110). The protective layer (160) may include an organic insulating material such as an acrylic resin, a silicone resin (siloxane resin), an epoxy resin, a polyimide resin, etc.

[0058] A pad element can be defined by a base substrate (100), pads (130), and a protective layer (160). The pad element can be provided as a pad portion of an electric element for supplying power and signals to the circuit wiring of the electric element.

[0059] A circuit board (PCB) for supplying power, current, etc. to the pad element may be disposed on the pad element and electrically connected to the pads (130). According to exemplary embodiments, the circuit board (PCB) may be attached or fixed to the pad element through a bonding structure (AL).

[0060] A circuit board (PCB) may include a core layer (200) and a wiring layer formed on the surface of the core layer (200). The wiring layer may include a first wiring layer (240) and a second wiring layer (250) formed respectively on the upper and lower surfaces of the core layer (200).

[0061] The circuit board (PCB) may further include a first coverlay film (220) and a second coverlay film (230). The first coverlay film (220) may be formed on the upper surface of the core layer (200) to cover the first wiring layer (240). The second coverlay film (230) may be formed on the lower surface of the core layer (200) to cover the second wiring layer (250).

[0062] The core layer (200) may include a flexible resin such as polyimide resin, MPI (Modified Polyimide), epoxy resin, polyester, cycloolefin polymer (COP), liquid crystal polymer (LCP), etc. In a preferred embodiment, the core layer (200) may include polyimide resin or MPI. Accordingly, the circuit board (PCB) may be provided as a flexible printed circuit board.

[0063] The first wiring layer (240) and the second wiring layer (250) may comprise silver (Ag), gold (Au), copper (Cu), aluminum (Al), platinum (Pt), palladium (Pd), chromium (Cr), titanium (Ti), tungsten (W), niobium (Nb), tantalum (Ta), vanadium (V), iron (Fe), manganese (Mn), cobalt (Co), nickel (Ni), tin (Sn), zinc (Zn), molybdenum (Mo), calcium (Ca), or an alloy containing at least one of these metals. In some embodiments, the first and second wiring layers (240, 250) may comprise copper or a copper alloy.

[0064] A circuit board (PCB) may include a through hole (TH) in which a first wiring layer (240) and a second wiring layer (250) are connected to each other. The through hole (TH) may penetrate the core layer (200). The first wiring layer (240) and the second wiring layer (250) are connected to each other through a wiring connection portion (260), and the wiring connection portion (260) may be formed on the side wall of the through hole (TH). The wiring connection portion (260) may be formed substantially integrally with the first wiring layer (240) and the second wiring layer (250) on the side wall of the through hole (TH).

[0065] The bonded structure (AL) can be formed using adhesive tapes such as optically clear resin (OCR) or pressure-sensitive adhesive (PSA).

[0066] As illustrated in FIG. 1, the bonding structure (AL) may include trenches (TR) corresponding to the pad rows. For example, a plurality of trenches (TR) may be formed in the bonding structure (AL) along the first direction.

[0067] According to exemplary embodiments, the trench (TR) may have a shape in which one end is open and the other end is closed. Accordingly, the junction structure (AL) may have a structure in which one end is open and the other end is closed. The trench (TR) may be open toward the component region (DA) along the extension direction of the circuit wiring (140).

[0068] A trench (TR) can be formed corresponding to each pad row. According to the embodiment illustrated in FIG. 1, one trench (TR) can correspond to one pad row. Accordingly, when observed in the planar direction of FIG. 1, one pad row can be exposed through one trench (TR).

[0069] As illustrated in FIG. 1, the joining structure (AL) may include a blocking section (BP) and a merging section (MP). A blocking section (BP) may be positioned between the two sides of the joining structure (AL) and adjacent trenches (TR) to separate the trenches (TR) from one another. The blocking section (BP) may extend in the second direction.

[0070] The merging section (MP) extends in the first direction and can connect the blocking sections (BP) to each other. The closed other end of the joining structure (AL) can be provided by the merging section (MP).

[0071] The circuit board (PCB) can be electrically connected to the pad (130) through a conductive structure (CS). The conductive structure (CS) can be provided as an intermediary structure between the circuit board (PCB) and the pad (130).

[0072] According to exemplary embodiments, the conductive structure (CS) may include solder pillars. For example, the solder pillars may be formed through surface mounting technology (SMT) that includes filling a through hole (TH) with a solder paste containing lead (Pb), tin (Sn), etc., and a reflow process.

[0073] The conductive structure (CS) can come into contact with the upper surface of the pad (130), penetrate the through hole (TH), and come into contact with the wiring connection part (260).

[0074] Accordingly, the first wiring layer (240) and the second wiring layer (250) can be electrically connected to the pad (130) together through the conductive structure (CS). Thus, driving power, data signals, etc. can be applied to the electrical device placed in the device area (DA) through the circuit board (PCB)-conductive structure (CS)-pad (130).

[0075] According to embodiments of the present invention, a trench (TR) with one end open can be formed in a bonding structure (AL) that attaches / fixes a circuit board (PCB). The trench (TR) provides a space for forming a conductive structure (CS), such as in a soldering process or a reflow process, and can also provide a path for the discharge of outgas generated by high-temperature processes such as the soldering process or the reflow process.

[0076] Therefore, the formation of defects such as voids within the conductive structure (CS) due to heat generated in the above high-temperature process can be suppressed. Thus, a stable conductive intermediate path can be formed between the circuit board (PCB) and the pad (130).

[0077] According to exemplary embodiments, the other end of the bonding structure (AL) is closed to stably support the circuit board (PCB) during the SMT process and to facilitate gas evacuation to the one end. Additionally, through the merging portion (MP) of the bonding structure (AL), it is possible to stably perform coupling with additional circuit structures and connection structures (integrated circuits, connectors, etc.) through the other end of the circuit board (PCB).

[0078] FIGS. 3 through 5 are schematic partial enlarged plan views illustrating pad connection structures according to some embodiments. For example, FIGS. 3 through 5 are plan views illustrating a portion of a pad connection structure around a single row of pads. Detailed descriptions of configurations and structures that are substantially the same or similar as those described with reference to FIGS. 1 and 2 are omitted. For convenience of illustration and description, detailed configurations and structures of a circuit board (PCB) are omitted in FIG. 5.

[0079] Referring to FIG. 3, one end of a trench (TR) included in a bonding structure (AL) may have a reduced width. For example, the portion of the trench (TR) where the pad row is placed may have a second width (W2), and the one end of the trench (TR) may have a first width (W1). The first width (W1) may be smaller than the second width (W2). As the width is reduced at the one end of the trench (TR), outgas generated during the SMT process can be more easily moved to the one end.

[0080] In some embodiments, the width of the first width (W1) may be 0.1 mm or more. For example, the width of the first width (W1) may be 0.1 mm to 3 mm, 0.2 mm to 2 mm, or 0.3 mm to 1 mm. Within the above range, outgassing can be sufficiently promoted and the space for forming the conductive structure (CS) can be stably secured.

[0081] Referring to FIG. 4, one end of the trench (TR) included in the bonding structure (AL) may have an increased width. For example, the portion of the trench (TR) where the pad row is placed may have a second width (W2), and the one end of the trench (TR) may have a first width (W1). The first width (W1) may be larger than the second width (W2). As the width of the one end of the trench (TR) is expanded, the volume of the exhaust path for outgas generated during the SMT process may be increased.

[0082] Referring to FIG. 5, one end of the circuit board (PCB) may not overlap with the junction structure (AL). Accordingly, an opening (OP) in which the junction structure (AL) is excluded may be formed between the one end of the circuit board (PCB) and the pad element. The opening (OP) extends in the first direction and may be connected to or merged with the trenches (TR). Outgases moved from the trenches (TR) in the second direction may be collected in the opening (OP) and diffused and discharged along the first direction.

[0083] FIG. 6 is a schematic plan view showing a transparent display device according to exemplary embodiments. FIG. 7 is a schematic partial enlarged plan view showing a circuit arrangement around a pixel according to exemplary embodiments. FIG. 8 is a schematic cross-sectional view showing a transparent display device according to exemplary embodiments. For example, FIG. 8 is a cross-sectional view cut along the line II-II' of FIG. 7.

[0084] Referring to FIGS. 6 to 8, a transparent display device may include a plurality of light-emitting element rows (LC) disposed on a base substrate (100). Each light-emitting element row (LC) extends in the second direction, and a plurality of light-emitting element rows (LC) may be repeatedly arranged along the first direction. A light-emitting element row (LC) may include a circuit wiring (140) and a plurality of light-emitting elements (180) connected to the circuit wiring (140).

[0085] A series of light-emitting elements (LC) can be placed in an element region (DA) of a transparent display device. For example, a base substrate (100) may include an element region (DA) and a pad region (PA) (see FIG. 1). A pad connection structure described above is placed on the pad region (PA) of the base substrate (100), and light-emitting elements (180) arranged on the element region (DA) can be connected to the pads (130) through circuit wiring (140).

[0086] The circuit wiring (140) may include a first driving wiring (142) and a second driving wiring (144). The circuit wiring (140) may further include a connecting wiring (155). The connecting wiring (155) may include wirings for interconnection / signal input between the driving wirings and the light-emitting elements (180).

[0087] As illustrated in FIG. 8, circuit wiring (140, 155) can be attached to the upper surface of the base substrate (100) through a point adhesive layer (110). As described with reference to FIG. 2, the circuit wiring (140, 155) may be placed at substantially the same level as the pad (130) and may have the same structure. For example, the circuit wiring (140, 155) may have a laminated structure of a metal pattern (121) and a capping layer (123).

[0088] According to exemplary embodiments, the first driving wire (142) and the second driving wire (144) may each be power wires. For example, either the first driving wire (142) and the second driving wire (144) may correspond to a common power wire, and the other may correspond to a pixel power wire. In some embodiments, the first driving wire (142) may correspond to a pixel power wire, and the second driving wire (144) may correspond to a common power wire.

[0089] In some embodiments, either the first driving wire (142) and the second driving wire (144) corresponds to a driving voltage supply wire, and the other may correspond to a ground wire. In one embodiment, the first driving wire (142) corresponds to a ground wire, and the second driving wire (144) corresponds to a driving voltage supply wire.

[0090] The first driving wire (142) and the second driving wire (144) extend parallel to each other, and when observed in a planar direction, a plurality of light-emitting elements (180) can be arranged along the second direction between the first driving wire (142) and the second driving wire (144).

[0091] The protective layer (160) can cover the circuit wiring (140) together with the pads (130) in the pad area (PA).

[0092] The connecting wiring (155) may include a data wiring (156). The data wiring (156) extends in the second direction, and a plurality of light-emitting elements (180) may be connected in series through the data wiring (156). For example, the light-emitting element (180) includes an input terminal and an output terminal into which a driving signal is input from the data wiring (156), and the data wiring (156) may extend from the output terminal to connect to the input terminal of an adjacent light-emitting element (180). The data wiring (156) may include an input pad (156a) and an output pad (156b) connected to the input terminal and the output terminal, respectively.

[0093] The connecting wiring (155) may include a power input line that supplies power to the light-emitting element (180). The power input line may include an individual pixel power input line (155a) and a common power input line (155b).

[0094] The individual pixel power input line (155a) and the common power input line (155b) can each be connected to the first driving wire (142) and the second driving wire (144).

[0095] A first pad (157a) and a second pad (157b), which are connected to the power terminals of the light-emitting element (180), can be connected to the ends of the individual pixel power input line (155a) and the common power input line (155b), respectively.

[0096] The light-emitting element (180) can be mounted on the protective layer (160) through a conductive intermediate structure (170) and electrically connected to the circuit wiring (140).

[0097] The conductive intermediate structure (170) may include solder bumps containing tin (Sn), lead (Pb), etc. The conductive intermediate structure (170) may come into contact with the aforementioned pads and / or terminals included in the circuit wiring (140). The conductive intermediate structure (170) may be formed together through the same process using substantially the same material as the conductive structure (CS) in the pad area (PA).

[0098] The light-emitting element (180) may include a light-emitting diode (RGB) and an integrated circuit chip (IC). The light-emitting diode (RGB) may include a red (R) pixel or red light-emitting diode (LED), a green (G) pixel or green light-emitting diode (LED), and a blue (B) pixel or blue light-emitting diode (LED).

[0099] In some embodiments, as shown in FIG. 8, the light-emitting diode (RGB) and the integrated circuit chip (IC) may be integrated into a single package or module. For example, the light-emitting element (180) may be provided in the form of an LED package.

[0100] In contrast, light-emitting diodes (RGB) and integrated circuit chips (ICs) can be provided as separate units or individual chips.

[0101] For example, an individual pixel power input line (155a) can be connected to a light-emitting diode (RGB) through a first pad (157a), and a common power input line (155b) can be connected to an integrated circuit chip (IC) through a second pad (157b).

[0102] The encapsulation layer (190) can be formed on the protective layer (160) to cover the light-emitting element (180). The encapsulation layer (190) may include an organic insulating material such as an acrylic resin, a silicone resin (siloxane resin), an epoxy resin, a polyimide resin, etc.

[0103] A cover substrate (195) may be laminated on an encapsulation layer (190). The cover substrate (195) may include a transparent resin film or glass substrate that is substantially identical or similar to the base substrate (100). The cover substrate (195) may be provided as a window substrate of a transparent display device that is exposed to the outside.

[0104] In some embodiments, the encapsulation layer (190) may comprise a pressure-adhesive optically transparent resin (OCR). In this case, a cover substrate (195) may be directly attached to the encapsulation layer (190).

[0105] The transparent display device described above is connected to a pad (130) through circuit wiring (140), and electrical signals such as power and current can be applied to the transparent display device through a circuit board (PCB). As described above, outgas can be efficiently discharged by using a pad connection structure according to exemplary embodiments, thereby improving the reliability of the conductive structure (CS). Accordingly, the application of power / signals to the light-emitting elements (180) and / or integrated circuit chips (IC) of the transparent display device can be implemented stably and uniformly, and voltage drop, resistance increase, etc. caused by defects in the conductive structure (CS) can be suppressed.

[0106] The application of the pad connection structure according to the exemplary embodiments described above is not limited to transparent display devices. For example, the pad connection structure can be applied to various electrical devices such as antenna devices, touch sensors, motion sensors, etc.

Claims

1. A pad element comprising a base substrate and pads arranged on the base substrate; A circuit board disposed on the above pads and comprising a wiring layer; A conductive structure that electrically connects the wiring layer and the pads; and A pad connection structure comprising a circuit board attached to the pad element and a bonding structure including a trench with one end open.

2. A pad connection structure according to claim 1, wherein the other end, which is opposite to the one end of the trench, is closed.

3. A pad connection structure according to claim 2, wherein the pads are exposed from the bonding structure through the trench.

4. A pad connection structure according to claim 3, wherein the pads are arranged in a second direction parallel to the upper surface of the base substrate to define a pad row, and a plurality of pad rows are arranged along a first direction parallel to the base substrate and intersecting the second direction.

5. In claim 4, the trench is formed corresponding to each of the pad rows, and The above joint structure comprises a pad connection structure including a blocking portion that separates the trenches, and a merging portion that closes the other ends of the trenches and connects the blocking portions.

6. A pad connection structure according to claim 1, wherein one end portion of the trench has a reduced width.

7. A pad connection structure according to claim 1, wherein one end portion of the trench has an expanded width.

8. A pad connection structure according to claim 1, wherein one end of the circuit board does not overlap with one end of the bonding structure, and an opening is formed between the one end of the circuit board and the pad element that communicates with the open one end of the trench.

9. In claim 1, the circuit board Core layer; A first wiring layer disposed on the upper surface of the core layer; A second wiring layer disposed on the bottom surface of the core layer; A through hole penetrating the core layer; and A pad connection structure comprising a wiring connection portion formed on the side wall of the through hole and connecting the first wiring layer and the second wiring layer.

10. The pad connection structure of claim 9, wherein the conductive structure extends from the upper surface of each of the pads and is inserted into the through hole.

11. The pad connection structure of claim 10, wherein the conductive structure contacts the wiring connection portion within the through hole.

12. The pad connection structure of claim 10, wherein the conductive structure comprises solder pillars.

13. In claim 1, the pad element further comprises circuit wiring connected to each of the pads, and A pad connection structure in which one end of the above trench is open toward the extension direction of the circuit wiring from the pads.

14. A pad connection structure according to claim 1, wherein the pads each comprise a metal pattern and a capping layer formed on the surface of the metal pattern.

15. Pad connection structure of claim 1; Circuit wiring connected to the pads of the pad connection structure; and A transparent display device comprising light-emitting elements arranged on the base substrate and electrically connected to the circuit wiring.

16. In claim 15, the base substrate comprises a pad region where the pads are arranged and a device region where the light-emitting elements are arranged, and A transparent display device in which one end of the trench of the pad connection structure is open toward the element area.

17. The invention of claim 15 further comprises a conductive intermediate structure connecting the circuit wiring and the light-emitting elements, and A transparent display device in which the above conductive mediating structure comprises the same material as the above conductive structure.

18. In claim 15, the circuit wiring comprises a first driving wiring and a second driving wiring spaced apart from each other in parallel, and A transparent display device in which the light-emitting elements are arranged between the first driving wire and the second driving wire to form a row of light-emitting elements.

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