Electronic devices

Abstract

To improve a performance of an electronic device.SOLUTION: A display device DSP1 comprises: a substrate; a wiring 31 arranged onto the substrate; an insulation layer 14 that is an inorganic insulation layer formed by an inorganic material, and coats the wiring 31; and a bump electrode 33 that is connected to the wiring 31, and is projected from the insulation layer 14. The bump electrode 33 contains: a conductive part 33A that is formed by a first metal material, and is connected to the wiring 31; and a conductive part 33B that is formed by a solder containing tin, and is arranged onto the conductive part 33A. The conductive part 33A contains: a part 33P1 that is connected to the wiring 31 at a position overlapped to an open part 14H1 formed onto the insulation layer 14; and a part 33P2 that is arranged so as to be separated from the part 33P1, and is connected to the wiring 31 at a position overlapped with the open part 14H2 formed to the insulation layer 14.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to an electronic device. [Background Art]

[0002] There is an electronic device in which an electronic component is mounted on a plurality of electrodes arranged on a substrate. For example, Japanese Patent Laid-Open No. 2014-197619 (Patent Document 1) describes an electronic device in which LED (Light Emitting Diode) elements are mounted on a plurality of electrodes arranged on a substrate. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Laid-Open No. 2014-197619 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] In the case of an electronic device in which an electronic component is mounted on a terminal formed on a substrate, a bump electrode may be formed on the substrate in order to facilitate connection between the electrode of the electronic component and the terminal on the substrate. According to studies by the inventor of the present application, observation of an electronic device after mounting an electronic component has revealed that a void may be formed between the bump electrode and the electrode of the electronic component in some cases.

[0005] An object of the present invention is to provide a technique for improving the performance of an electronic device. [Means for Solving the Problem]

[0006] An electronic device according to one embodiment includes a first substrate, a first wiring arranged on the first substrate, an inorganic insulating layer made of an inorganic material covering the first wiring, and a first bump electrode connected to the first wiring and protruding from the first insulating layer. The first bump electrode includes a first conductor portion made of a first metal material and connected to the first wiring, and a second conductor portion made of tin-containing solder and arranged on the first conductor portion. The first conductor portion includes a first part connected to the first wiring at a position overlapping with a first opening formed in the first insulating layer, and a second part spaced apart from the first part and connected to the first wiring at a position overlapping with a second opening formed in the first insulating layer.

[0007] An electronic device according to another embodiment includes a first substrate, first wiring disposed on the first substrate, an inorganic insulating layer made of an inorganic material covering the first wiring, and a first bump electrode connected to the first wiring and protruding from the first insulating layer. The first bump electrode includes a first conductor portion made of a first metal material and connected to the first wiring, and a second conductor portion made of tin-containing solder and disposed on the first conductor portion. The first conductor portion includes a first part connected to the first wiring in a first region of a first opening formed in the first insulating layer, and a second part spaced apart from the first part and connected to the first wiring in a second region of the first opening. [Brief explanation of the drawing]

[0008] [Figure 1] This is a plan view showing an example configuration of a micro-LED display device, which is one embodiment of an electronic device. [Figure 2] Figure 1 is a circuit diagram showing an example of the circuit configuration around a pixel. [Figure 3] This is a transparent, enlarged plan view showing an example of the peripheral structure of LED elements arranged in each of the multiple pixels of the display device shown in Figure 1. [Figure 4] This is an enlarged cross-sectional view along line AA in Figure 3. [Figure 5] Figure 3 is an enlarged plan view showing the state before the LED elements were installed. [Figure 6] This is an enlarged cross-sectional view along line BB in Figure 5. [Figure 7] Figure 4 is an enlarged cross-sectional view of the vicinity of the interface between the wiring and the bump electrode. [Figure 8] Figure 7 is a transparent, enlarged plan view showing the planar positional relationship between the copper-containing conductive portion, the wiring, and the opening formed in the insulating layer of the bump electrode. [Figure 9] Figure 6 is an enlarged cross-sectional view of the vicinity of the interface between the wiring and the bump electrode. [Figure 10] Figure 9 is a transparent, enlarged plan view showing the planar positional relationship between the conductive portion made of solder, the wiring, and the opening formed in the insulating layer of the bump electrode shown. [Figure 11] This is an enlarged cross-sectional view showing an example of the analysis in Figure 9. [Figure 12] This is a transparent enlarged plan view showing a modified version of Figure 10. [Figure 13] This is a transparent enlarged plan view showing another variation of Figure 10. [Figure 14] This is an enlarged cross-sectional view along the CC line in Figure 13. [Figure 15] Figures 13 and 14 are transmissive magnified plan views showing the state in which the anode electrode of an LED element is connected to the bump electrode. [Figure 16] This is an explanatory diagram showing an example of a process flow for a method of manufacturing a display device, which is one embodiment of an electronic device. [Figure 17] This is an enlarged cross-sectional view showing a modified example from Figure 4. [Figure 18] Figure 17 is a magnified, transmitted view of the area around the bump electrode before the LED element was mounted. [Figure 19] This is an enlarged cross-sectional view along the DD line in Figure 18. [Figure 20] This is a transparent enlarged plan view showing a modified version of Figure 18. [Figure 21] Figure 20 is an enlarged cross-sectional view along the EE line. [Figure 22] It is an enlarged transmission plan view showing a state where an anode electrode of an LED element is connected to the bump electrodes shown in FIG. 20 and FIG. 21. Mode for Carrying Out the Invention

[0009] Hereinafter, each embodiment of the present invention will be described with reference to the drawings. It should be noted that the disclosure is merely an example, and any appropriate modifications that can be easily conceived by those skilled in the art while maintaining the gist of the invention shall naturally fall within the scope of the present invention. In addition, in order to make the description clearer, the drawings may schematically show the width, thickness, shape and the like of each part compared to the actual embodiment, which are merely examples and do not limit the interpretation of the present invention. Furthermore, in the present specification and each drawing, elements that are the same as those already described with respect to the preceding drawings are denoted by the same or related reference numerals, and detailed description thereof may be omitted as appropriate.

[0010] In the following embodiments, as examples of an electronic device in which bump electrode arrays for mounting a plurality of electronic components are arranged, a micro LED display device mounted with a plurality of micro LED elements and a bump electrode array device before micro LED elements are mounted will be described.

[0011] <Electronic device> First, a configuration example of the micro LED display device which is the electronic device of the present embodiment will be described. FIG. 1 is a plan view showing a configuration example of a micro LED display device which is an embodiment of the electronic device. In FIG. 1, the boundary between a display area DA and a peripheral area PFA, a control circuit 5, a drive circuit 6, and each of a plurality of pixels PIX are indicated by two-dot chain lines. FIG. 2 is a circuit diagram showing a configuration example of a circuit around the pixel shown in FIG. 1.

[0012] As shown in Figure 1, the display device DSP1 of this embodiment has a display area DA, a peripheral area PFA that surrounds the display area DA in a frame shape, and a plurality of pixels PIX arranged in a matrix within the display area DA. The display device DSP1 also has a substrate 10, a control circuit 5 formed on the substrate 10, and a drive circuit 6 formed on the substrate 10. The substrate 10 is made of, for example, glass or resin. The substrate 10 has a surface 10f and a surface 10b opposite to surface 10f.

[0013] Control circuit 5 is a control circuit that controls the driving of the display function of the display device DSP1. For example, control circuit 5 is a driver IC (Integrated Circuit) mounted on the substrate 10. In the example shown in Figure 1, control circuit 5 is arranged along one of the four short sides of the substrate 10. In this embodiment, control circuit 5 also includes a signal line driving circuit that drives the wiring (video signal wiring) VL (see Figure 2) connected to multiple pixels PIX. However, the location and configuration examples of control circuit 5 are not limited to the example shown in Figure 1, and there are various modifications. For example, in Figure 1, a circuit board such as a flexible substrate may be connected to the location shown as control circuit 5, and the above-mentioned driver IC may be mounted on the circuit board. Also, for example, the signal line driving circuit that drives the wiring VL may be formed separately from control circuit 5.

[0014] The drive circuit 6 includes a circuit that drives the scan signal line GL (see Figure 2, described later) among the multiple pixels PIX. The drive circuit 6 also includes a circuit that supplies a reference potential to the LED element mounted on each of the multiple pixels PIX. The drive circuit 6 drives the multiple scan signal lines GL based on the control signal from the control circuit 5. In the example shown in Figure 1, the drive circuit 6 is arranged along each of the two long sides of the four sides of the substrate 10. However, the position and configuration of the drive circuit 6 are not limited to the example shown in Figure 1, and various modifications are possible. For example, in Figure 1, a circuit board such as a flexible substrate may be connected to the position shown as the control circuit 5, and the control circuit 5 and drive circuit 6 described above may be mounted on the circuit board.

[0015] Next, an example of a pixel PIX circuit configuration will be explained using Figure 2. Note that Figure 2 shows four representative pixel PIXs, but each of the multiple pixel PIXs shown in Figure 1 has a circuit similar to the pixel PIX shown in Figure 2. Hereafter, the circuit including the switch and LED element 20 of the pixel PIX may be referred to as the pixel circuit. The pixel circuit is a voltage signal type circuit that controls the light emission state of the LED element 20 in accordance with the video signal Vsg supplied from the control circuit 5 (see Figure 1).

[0016] As shown in Figure 2, the pixel PIX is equipped with an LED element 20. The LED element 20 is the micro light-emitting diode described above. The LED element 20 has an anode electrode 20EA and a cathode electrode 20EK. The cathode electrode 20EK of the LED element 20 is connected to the wiring VSL to which a reference potential (fixed potential) PVS is supplied. The anode electrode 20EA of the LED element 20 is electrically connected to the drain electrode ED of the switching element SW via the wiring 31.

[0017] Each pixel (PIX) is equipped with a switching element (SW). The switching element (SW) is a transistor that controls the connection state (on or off) between the pixel circuit and the wiring VL in response to a control signal (Gs). The switching element (SW) is, for example, a thin-film transistor. When the switching element (SW) is in the ON state, the pixel circuit receives a video signal (Vsg) from the wiring VL.

[0018] The drive circuit 6 includes a shift register circuit, an output buffer circuit, etc. (not shown). The drive circuit 6 outputs a pulse based on the horizontal scanning start pulse transmitted from the control circuit 5 (see Figure 1) and outputs a control signal Gs.

[0019] Each of the multiple scan signal lines GL extends in the X direction. The scan signal lines GL are connected to the gate electrode of the switching element SW. When a control signal Gs is supplied to the scan signal lines GL, the switching element SW turns on, and a video signal Vsg is supplied to the LED element 20.

[0020] <Peripheral Structure of LED Element> Next, a description is given of the peripheral structure of an LED element disposed in each of the plurality of pixels PIX shown in FIG. 1. FIG. 3 is a transparent enlarged plan view showing an example of the peripheral structure of an LED element disposed in each of the plurality of pixels of the display device shown in FIG. 1. In FIG. 3, the illustration of the insulating layer 14 shown in FIG. 4 is omitted. In FIG. 3, the outlines of the semiconductor layer, electrodes, and scanning signal lines are shown by dotted lines. FIG. 4 is an enlarged cross-sectional view taken along line A-A of FIG. 3. FIG. 5 is an enlarged plan view showing a state before the LED element shown in FIG. 3 is mounted. FIG. 6 is an enlarged cross-sectional view taken along line B-B of FIG. 5. FIG. 7 is an enlarged cross-sectional view near the bonding interface between the wiring and the bump electrode shown in FIG. 4. FIG. 8 is a transparent enlarged plan view showing the planar positional relationship among the copper-containing conductor portion, the wiring, and the opening formed in the insulating layer among the bump electrodes shown in FIG. 7. In FIG. 8, the outline of the opening 14H1, the outline of the opening 14H2, the outline of the portion 33P1 of the conductor portion 33A, the outline of the portion 33P2 of the conductor portion 33A, and each of the wiring 31 are shown by dotted lines. In addition, in FIG. 8, the outline of the anode electrode 20EA of the LED element 20 is shown by a two-dot chain line. In addition, in FIG. 8, the outline of the conductor portion 33B is shown by a solid line. In each of the transparent enlarged plan views described below, the same line types as in FIG. 8 are used for illustration.

[0021] As shown in Figure 3, the display device DSP1 has multiple pixels PIX, including pixel PIX1 (in the example shown in Figure 4, pixels PIX1, PIX2, and PIX3). Each of the multiple pixels PIX has a switching element SW, an LED element (light-emitting element) 20, wiring 31, and wiring 32. Each of pixels PIX1, PIX2, and PIX3 is equipped with an LED element 20 that emits visible light of one of the following colors, for example, red, green, and blue, and a switching element SW that drives the LED element 20 is formed therein. By controlling the output and timing of the visible light emitted from the LED elements of pixels PIX1, PIX2, and PIX3, color display becomes possible. When multiple pixels PIX that emit visible light of different colors are combined in this way, each pixel PIX for each color is sometimes called a sub-pixel, and the set of multiple pixels PIX is sometimes called a pixel. In this embodiment, the part corresponding to the sub-pixel is called a pixel PIX.

[0022] Wiring 31 is electrically connected to the drain electrode ED of the switching element SW and the anode electrode 20EA of the LED element 20, respectively. Wiring 32 is connected to the source electrode ES of the switching element SW. In the example shown in Figure 3, wiring 32 has a bent structure, with one end connected to the source electrode ES of the switching element SW and the other end connected to wiring VL. The scan signal line GL is used as the gate electrode EG of the switching element SW.

[0023] The display device DSP1 further includes a wiring VL that extends across multiple pixels PIX (see Figure 2) along the Y direction and is electrically connected to wiring 32, and a wiring VSL that extends across multiple pixels PIX along the X direction intersecting the Y direction (orthogonal in Figure 3) and is electrically connected to the cathode electrode 20EK of the LED element 20. Wiring VL and wiring VSL intersect at the wiring intersection LXP shown in Figure 3 via an insulating layer 41. Since the insulating layer 41 is interposed between wiring VL and wiring VSL, wiring VL and wiring VSL are electrically isolated. Note that the layout shown in Figure 3 is an example, and there are various modifications. For example, as one modification of Figure 3, the switching element SW may have a gate electrode (not shown), and the gate electrode may be connected to the scanning signal line GL. In this modification, the scanning signal line GL may be positioned so as not to overlap with the semiconductor layer 50.

[0024] As shown in Figure 4, the display device DSP1 is an electronic device comprising a substrate 10 made of glass or resin, and a plurality of insulating layers laminated on the substrate 10. The plurality of insulating layers of the display device DSP1 include insulating layer 11, insulating layer 12, insulating layer 13, and insulating layer 14, which are laminated on the substrate 10. The substrate 10 has a surface 10f and a surface 10b opposite to surface 10f. Each of the insulating layers 11, 12, 13, and 14 is laminated on surface 10f of the substrate 10.

[0025] The switching element SW includes an insulating layer 12 formed on a substrate 10, a semiconductor layer 50 formed on the insulating layer 12, a drain electrode ED connected to the drain region of the semiconductor layer 50, a source electrode ES connected to the source region of the semiconductor layer 50, and an insulating layer 13 covering the semiconductor layer 50.

[0026] The example shown in Figure 4 is a bottom-gate configuration where the gate electrode EG is located between the semiconductor layer 50 and the substrate 10. In the bottom-gate configuration, the portion of the insulating layer 12 between the gate electrode EG and the semiconductor layer 50 functions as the gate insulating layer. The insulating layer 12 also functions as a base layer for forming the semiconductor layer 50. Note that the position of the gate electrode EG is not limited to the example shown in Figure 4; for example, a top-gate configuration may also be used as a modification.

[0027] Each of the insulating layers 11, 12, 13, and 14 is an inorganic insulating film composed of an inorganic material. The materials constituting each of the insulating layers 11, 12, 13, and 14 are not particularly limited. For example, silicon oxide (SiO2) and silicon nitride (SiN) can be used. The semiconductor layer 50 is a semiconductor film in which a silicon film made of silicon is doped with P-type or N-type conductive impurities.

[0028] The source electrode ES and the drain electrode ED are contact plugs for making electrical contact with either the source region or the drain region of the semiconductor layer 50. Examples of contact plug materials include tungsten. In a modified version of Figure 4, contact holes are formed in the insulating layer 13 to expose the source region and drain region of the semiconductor layer 50, and a portion of the wiring 31 and a portion of the wiring 32 are embedded within the contact holes. In this case, the portions of the wiring 31 and 32 embedded within the contact holes contact the semiconductor layer 50, and the contact interfaces between the wiring 31 and 32 and the semiconductor layer 50 can be considered as the drain electrode ED and the source electrode ES.

[0029] Furthermore, as shown in Figure 5, the display device DSP1 includes a plurality of bump electrodes 33 and a plurality of bump electrodes 34 arranged regularly in a plan view. The bump electrodes 33 and 34 are terminals for mounting electronic components on the substrate 10 (see Figure 4). In this embodiment, the bump electrodes 33 and 34 are terminals for mounting the LED element 20 shown in Figure 4. In the example shown in Figure 4, the bump electrode 33 is connected to the anode electrode 20EA of the LED element 20, and the bump electrode 34 is connected to the cathode electrode 20EK of the LED element 20. The pair of bump electrodes 33 and bump electrodes 34 are arranged adjacent to each other in the area where the LED element 20 (see Figure 3) is to be mounted.

[0030] As illustrated in Figure 7, the wiring 31 is a laminated film of a conductor layer 30A and a conductor layer 30B. The conductor layer 30A is made of titanium or a titanium alloy and is formed on the insulating layer 13. The conductor layer 30B is made of aluminum or an aluminum alloy and is laminated on the conductor layer 30A. However, as a modified example, the conductor layer 30B made of aluminum or an aluminum alloy may be sandwiched between conductor layers 30A made of titanium or a titanium alloy.

[0031] When the conductor portion 33A of the bump electrode 33 and the conductor portion 34A of the bump electrode 34 shown in Figure 4 are made of copper or a copper alloy, an aluminum film is advantageous over a titanium film for the metal film to which the conductor portions 33A and 34A are connected (the metal film that forms the outermost surface of the wiring 31 or wiring VSL) in that it provides higher connection reliability. On the other hand, since the surface of an aluminum film is more prone to oxidation than that of a titanium film, it is preferable to have a step to remove the oxide film before forming the conductor portions 33A and 34A. There are various variations in the step to remove the oxide film, but for example, a treatment in which the aluminum oxide film is replaced with a zincate film (called zincate treatment) can be exemplified. When this zincate treatment is applied, a zinc-containing conductor film is formed between the conductor layer 30B shown in Figure 7 and the conductor portion 33A of the bump electrode 33.

[0032] As shown in Figure 7, the bump electrode 33 is connected to the wiring 31 at a position overlapping with openings 14H1 and 14H2 formed in the insulating layer 14, and protrudes from the insulating layer 14. The bump electrode 33 is made of copper or a copper alloy and includes a conductive portion 33A connected to the conductive layer 30B of the wiring 31, and a conductive portion 33B made of tin-containing solder and formed on the conductive portion 33A. By using a conductive portion 33A made of copper or a copper alloy in this way, the electrical characteristics of the bump electrode 33 can be improved.

[0033] In this embodiment, copper or a copper alloy can be used as the metal material constituting the conductor portion 33A, but various modifications can be applied. From the viewpoint of improving electrical characteristics, the metal material constituting the conductor portion 33A is preferably a material with higher electrical conductivity than the solder constituting the conductor portion 33B. Furthermore, in the process of mounting the LED element 20 shown in Figure 4, from the viewpoint of avoiding deformation of the conductor portion 33A when the bump electrode 33 is heated, the metal material constituting the conductor portion 33A is preferably a material with a higher melting point than the solder constituting the conductor portion 33B.

[0034] Furthermore, the conductor portion 33A may be a laminated film formed by stacking films of multiple types of metal materials. For example, if the conductor portion 33A is a laminated film in which a nickel film is stacked on a copper film made of copper or a copper alloy, oxidation of the surface of the conductor portion 33A can be suppressed.

[0035] Incidentally, as shown in Figure 7, the conductor portion 33A of the bump electrode 33 has a portion 33P1 that is connected to the wiring 31 at a position overlapping with the opening 14H1 formed in the insulating layer 14, and a portion 33P2 that is spaced apart from portion 33P1 and connected to the wiring 31 at a position overlapping with the opening 14H2 formed in the insulating layer 14. As shown in Figures 7 and 8, unlike the conductor portion 33A, the conductor portion 33B is not separated into two parts. The conductor portion 33B is connected to the anode electrode 20EA (see Figure 7) and is connected to portions 33P1 and 33P2, respectively. In the example shown in Figure 7, the insulating layer 14 is positioned at a position overlapping with a portion of the conductor portion 33B of the bump electrode 33 (specifically, between the openings 14H1 and 14H2). The conductor portion 33B is in contact with the insulating layer 14 between portions 33P1 and 33P2 of the conductor portion 33A.

[0036] In this embodiment, the bump electrode 33 has the structure shown in Figure 7, which prevents voids (air bubbles) from forming between the bump electrode 33 and the anode electrode 20EA. The reason for this will be explained below. Figure 9 is an enlarged cross-sectional view of the vicinity of the junction interface between the wiring and the bump electrode shown in Figure 6. Figure 10 is a transparent enlarged plan view showing the planar positional relationship between the conductive part made of solder, the wiring, and the opening formed in the insulating layer of the bump electrode shown in Figure 9. Figure 11 is an enlarged cross-sectional view showing an example of a design based on Figure 9. Figure 12 is a transparent enlarged plan view showing a modified example based on Figure 10.

[0037] In the manufacturing process of the display device DSP1 shown in Figure 4, the bump electrode 33 has the structure shown in Figures 9 and 10 before the LED element 20 is mounted. The conductor portion 33A has portions 33P1 and 33P2 that are spaced apart from each other. Portion 33P3 of the conductor portion 33B is stacked on portion 33P1, and portion 33P4 of the conductor portion 33B is stacked on portion 33P2. In the example shown in Figures 9 and 10, portions 33P3 and 33P4 are spaced apart from each other. However, in a modified example, portions 33P3 and 33P4 may be connected in some cases.

[0038] In the manufacturing process of the display device DSP1 shown in Figure 4, in the step of joining the LED element 20 to the bump electrode 33, the bump electrode 33 is heated while the anode electrode 20EA of the LED element 20 and the bump electrode 33 are in contact with each other. Various heating methods can be applied, but for example, the bump electrode 33 can be heated by irradiating it with laser light. By heating the bump electrode 33, the solder contained in the conductor portion 33B melts and deforms. In this embodiment, portions 33P3 and 33P4 of the conductor portion 33B shown in Figures 9 and 10 come into contact and become one. Also, as shown in Figure 7, the solder contained in the conductor portion 33B wets and spreads across the surface of the anode electrode 20EA, and the anode electrode 20EA and the conductor portion 33A are electrically connected via the conductor portion 33B.

[0039] Here, when forming a bump electrode to connect the anode electrode 20EA shown in Figure 4, one possible method for consideration is to connect a bump electrode 35 consisting of one conductor portion 35A and one conductor portion 35B to the anode electrode 20EA (see Figure 4), as shown in Figure 11. However, according to the inventor's research, in the example shown in Figure 11, it was found that a wall portion 35X tends to form around the periphery of the conductor portion 35B, which is made of solder. The larger the area of ​​the conductor portion 35B in a plan view, the more likely it is that a high wall portion 35X will be formed, and it is formed along the periphery of the bump electrode 35 in a plan view. At the top center of the bump electrode 35, there is a space surrounded by the wall portion 35X. When attempting to join the anode electrode 20EA shown in Figure 4 with such a space present, it is thought that the gas in the space surrounded by the wall portion 35X has nowhere to go and remains as a void.

[0040] On the other hand, in this embodiment, as shown in Figure 9, the conductor portion 33A has portions 33P1 and 33P2 that are spaced apart from each other. Portion 33P3 of the conductor portion 33B is stacked on portion 33P1, and portion 33P4 of the conductor portion 33B is stacked on portion 33P2. In this case, as shown in Figure 9, even if a wall portion 33X is formed at the top of portions 33P3 and 33P4, the height of the wall portion 33X is lower than the wall portion 35X shown in Figure 11. This is because the lengths of portions 33P3 and 33P4 in the Y direction are shorter than the length of the conductor portion 33B in the Y direction shown in Figure 11. Thus, even if a wall portion 33X is formed, if its height is low, the gas in the space surrounded by the wall portion 33X can be easily discharged to the outside.

[0041] Furthermore, as shown in Figure 9, in this embodiment, a space exists between portion 33P3 and portion 33P4 of the conductor portion 33B. As shown in Figure 10, the space between portion 33P3 and portion 33P4 of the conductor portion 33B has open ends at both ends.

[0042] As the solder contained in the bump electrode 33 melts, as shown in Figures 7 and 8, the portion 33P1, the portion 33P2, and the anode electrode 20EA (see Figure 7) are integrated via the conductive portion 33B. In other words, the display device DSP1 (see Figure 4) has an electronic component (LED element 20) with an anode electrode 20EA connected to the bump electrode 33. The conductive portion 33B of the bump electrode 33 is connected to the anode electrode 20EA and is also connected to the respective portions 33P1 and 33P2.

[0043] The gas surrounding the conductor portion 33B shown in Figure 9 is completely discharged to the outside through the space between portions 33P3 and 33P4 of the conductor portion 33B shown in Figure 10. Therefore, as shown in Figure 7, voids are less likely to remain between the anode electrode 20EA and the bump electrode 33 in the display device after the anode electrode 20EA and the bump electrode 33 are joined. In other words, in this embodiment, the space between portions 33P3 and 33P4 of the conductor portion 33B can be used as a gas discharge path, thus suppressing the generation of voids.

[0044] In the example shown in Figure 10, each of the portions 33P1 and 33P2 is a linear pattern extending in the X direction in a plan view. Similarly, each of the portions 33P3 and 33P4 is a linear pattern extending in the X direction in a plan view. Note that the direction in which each of the portions 33P1 and 33P2 extends is not limited to the X direction; for example, as shown in the modified example in Figure 12, each of the portions 33P1 and 33P2 may be a linear pattern extending in the Y direction. As shown in Figures 10 and 12, when each of the portions 33P1 and 33P2 is a linear pattern, it is easier to control the direction in which the solder contained in the conductor portion 33B spreads and the direction of gas discharge.

[0045] Furthermore, as shown in Figure 4, the display device DSP1 has a wiring VSL and bump electrodes 34 connected to the wiring VSL and protruding from the insulating layer 14. The wiring VSL is formed on the substrate 10, is spaced apart from the wiring 31, and is covered by the insulating layer 14. The bump electrodes 33 and 34 are arranged along the Y direction intersecting the X direction (see Figure 10). In other words, in the example shown in Figure 10, each of the portions 33P1 and 33P2 extends in the X direction intersecting the Y direction, which is the arrangement direction of the bump electrodes 33 and 34. On the other hand, in the modified example shown in Figure 12, each of the portions 33P1 and 33P2 extends in the Y direction, which is the arrangement direction of the bump electrodes 33 and 34.

[0046] As shown in the example in Figure 4, when the distance between the anode electrode 20EA and the cathode electrode 20EK is sufficiently large, the risk of a short circuit between the bump electrode 33 and the bump electrode 34 is small. However, when the distance between the anode electrode 20EA and the cathode electrode 20EK is small, the example shown in Figure 10 is preferable from the viewpoint of preventing a short circuit between the conductor portion 33B of the bump electrode 33 and the conductor portion 34B of the bump electrode 34. In the example shown in Figure 10, the solder spreads along the X direction, making it easier to control the range over which the solder spreads in the Y direction. Therefore, even when the distance between the anode electrode 20EA and the cathode electrode 20EK is small, it is possible to prevent a short circuit between these electrodes via the solder contained in the conductor portion 33B of the bump electrode 33 and the conductor portion 34B of the bump electrode 34.

[0047] As shown in Figure 6, the bump electrode 34 has the same structure as the bump electrode 33. That is, the bump electrode 34 is made of the same metallic material as the conductor portion 33A (e.g., copper or copper alloy) and includes a conductor portion 34A connected to the wiring VSL, and a conductor portion 34B made of solder containing tin and placed on the conductor portion 34A. The conductor portion 33A includes a portion 34P1 connected to the wiring VSL at a position overlapping with an opening 14H3 formed in the insulating layer 14, and a portion 34P2 positioned apart from portion 34P1 and connected to the wiring VSL at a position overlapping with an opening 14H4 formed in the insulating layer 14.

[0048] Figure 6 shows the state before the cathode electrode 20EK of the LED element 20 shown in Figure 4 is joined to the bump electrode 34. Therefore, the conductive portion 34B of the bump electrode 34 has a portion 34P3 stacked on portion 34P1 and a portion 34P4 stacked on portion 34P2. In the example shown in Figure 6, portions 34P3 and 34P4 are spaced apart from each other. However, in a modified example, portions 34P3 and a portion of portion 34P4 may be connected.

[0049] Figure 13 is a transmitted magnified plan view showing another modification of Figure 10. Figure 14 is a magnified cross-sectional view along the CC line in Figure 13. Figure 15 is a transmitted magnified plan view showing the anode electrode of an LED element connected to the bump electrodes shown in Figures 13 and 14.

[0050] Figures 13 and 14 show a modified substrate structure SUB2, which is a modified version of the substrate structure SUB1 shown in Figures 9 and 10. Figure 15 also shows a display device DSP2 in which the LED element 20 shown in Figure 4 is mounted on the bump electrode 33 of the substrate structure SUB2 shown in Figures 13 and 14. The modified version shown in Figures 13 and 14 differs from the example shown in Figures 9 and 10 in the following respects. In this modified version, the conductor portion 33A further has a portion 33P5 which is spaced apart from portions 33P1 and 33P2 and connected to the wiring 31 at a position overlapping with an opening 14H5 formed in the insulating layer 14. The conductor portion 33A further has a portion 33P6 which is spaced apart from portions 33P1, 33P2, and 33P5, and connected to the wiring 31 at a position overlapping with an opening 14H6 formed in the insulating layer 14. As shown in Figure 13, each of sections 33P1, 33P2, 33P5, and 33P6 is a circular pattern in plan view.

[0051] Furthermore, after mounting the LED element 20 shown in Figure 4, the conductor portion 33B is integrated as shown in Figure 15. That is, as shown in Figure 15, the display device further includes an electronic component (LED element 20) having an anode electrode 20EA connected to the bump electrode 33. The conductor portion 33A of the bump electrode 33 is connected to portions 33P1, 33P2, 33P5, and 33P6, respectively.

[0052] In this modified example, the conductor portion 33A is also separated into four parts. Therefore, when the conductor portion 33B is heated and melted to form a single unit, the spaces between parts 33P1, 33P2, 33P5, and 33P6 function as gas discharge paths. As a result, even in this modified example, it is possible to prevent the formation of a void between the anode electrode 20EA and the conductor portion 33B.

[0053] In this modified example, after the LED element 20 has been mounted, the insulating layer 14 is positioned at a location that overlaps with a portion of the conductor portion 33B of the bump electrode 33 (specifically, between openings 14H1, 14H2, 14H5, and 14H6). The conductor portion 33B is in contact with the insulating layer 14 between portions 33P1, 33P2, 33P5, and 33P6 of the conductor portion 33A.

[0054] <Method of manufacturing electronic devices> Next, as a representative example of the manufacturing method of the electronic device of this embodiment, the manufacturing method of the display device shown in Figure 4 will be described. Figure 16 is an explanatory diagram showing an example of the process flow of the manufacturing method of a display device, which is one embodiment of the electronic device. As shown in Figure 16, the manufacturing method of the electronic device of this embodiment includes a substrate structure preparation step, a bump electrode formation step, and an electronic component mounting step. Note that if the substrate structure before mounting the electronic components is shipped as a semi-finished product, the electronic component mounting step can be omitted.

[0055] In the substrate structure preparation process, a substrate structure SUB1 is prepared in a state before the bump electrode 33 shown in Figure 4 is formed. In the substrate structure preparation process, a substrate structure SUB1 is prepared comprising a substrate 10 made of glass or resin, wiring 31 formed on the substrate 10, and an insulating layer 14 covering the wiring 31. Insulating layers 11, 12, 13, and 14 are laminated on the substrate 10, and the wiring 31 is positioned between insulating layer 13 and insulating layer 14. Most of the substrate structure SUB1 is covered by the insulating layer 14. The insulating layer 14 has openings 14H1 (see Figure 9) and 14H2 (see Figure 9) formed in positions overlapping with the wiring 31, and openings 14H3 (see Figure 6) and 14H4 (see Figure 6) formed in positions overlapping with the wiring VSL.

[0056] If an oxide film is formed on the surface of the portion of the wiring 31 and wiring VSL that is exposed from the insulating layer 14, an oxide film removal process may be performed as a pretreatment before carrying out the bump electrode formation process to remove the oxide film.

[0057] Next, in the bump electrode formation process, bump electrodes 33 and 34 (see Figure 4), as explained using Figures 4 to 15, are formed. Below, a representative example of how to form the bump electrode 33 connected to the wiring 31 will be described. However, the bump electrode 34 connected to the wiring VSL can be formed using the same method as described below.

[0058] In the bump electrode formation process, the conductive portion 33A is formed by electroplating while current is applied to the wiring 31 shown in Figure 4 (first film formation step). Specifically, while current is applied to the wiring 31, the conductive portion 33A, made of copper or a copper alloy, is selectively formed by electroplating at the position overlapping with the opening 14H1, the position overlapping with the opening 14H2, and around the opening. In this case, the copper film (or copper alloy film) can be selectively grown from the exposed surface of the wiring 31. Furthermore, in this embodiment, the copper film can be selectively grown on the portion of the wiring 31 that is exposed from the insulating layer 14. For this reason, there is no need to prepare a large exposure device such as a large stepper. Note that current can be applied to the wiring 31 and the wiring VSL simultaneously, so the conductive portion 33A on the wiring 31 and the conductive portion 34A on the wiring VSL can be formed at the same time.

[0059] Next, with the wiring 31 energized, a conductor portion 33B made of tin-containing solder is selectively deposited on the conductor portion 33A (second deposition step). When depositing the solder film, as with the copper film, an electroplating method is used so that the solder film spreads isotropically on the surface of the energized conductor portion 33A, thereby depositing the conductor portion 33B. Through this step, a bump electrode 33 having two spaced-apart portions is obtained, as shown in Figures 9 and 10.

[0060] In the bump electrode formation process of this embodiment, a portion of the insulating layer 14 is used as a mask for forming portions 33P1 and 33P2 of the conductive portion 33A. As a result, as explained with reference to Figure 7, a bump electrode 33 is obtained in which the insulating layer 14 is positioned at a location that overlaps with a portion of the conductive portion 33B of the bump electrode 33 (specifically, between openings 14H1 and 14H2).

[0061] In some cases, the substrate structure SUB1 (see Figure 4) before the mounting of electronic components may be shipped as a semi-finished product. In this case, the electronic component mounting process shown in Figure 16 is omitted, and after the necessary inspections and packaging are performed on the substrate structure SUB1 shown in Figure 6, it is prepared for shipment. That is, the substrate structure SUB1 as an electronic device is obtained through the bump electrode formation process shown in Figure 16.

[0062] Next, in the electronic component mounting process shown in Figure 16, after the bump electrode formation process, the bump electrode 33 is electrically connected to the electronic component (LED element 20 in the example of Figure 4) as shown in Figure 4. In this process, for example, the conductor portion 33B and conductor portion 34B shown in Figure 6 are melted by irradiation with a laser. As a result, the bump electrode 33 is connected to the anode electrode 20EA of the LED element 20, and the bump electrode 34 is connected to the cathode electrode 20EK of the LED element. Note that, prior to this process, a solder film may be formed on the anode electrode 20EA and cathode electrode 20EK of the LED element 20 as shown in Figure 4. In this case, the conductor portion 33B made of solder and the solder film formed on the electrode can be easily integrated, so that the bump electrode 33 and the anode electrode 20EA can be reliably connected. The same applies to the bump electrode 34 and cathode electrode 20EK shown in Figure 4.

[0063] <Modified examples of bump electrodes> Next, we will describe a modified version of the bump electrode. Figure 17 is an enlarged cross-sectional view showing a modified version from Figure 4. Figure 18 is a transmitted magnified plan view of the area around the bump electrode before the LED element shown in Figure 17 is mounted. Figure 19 is an enlarged cross-sectional view along the DD line in Figure 18.

[0064] Figure 17 shows a modified display device DSP3, which is a modified version of the display device DSP1 shown in Figure 4. Figures 18 and 19 show a substrate structure SUB3, which is a modified version of the substrate structure SUB1 shown in Figures 9 and 10.

[0065] The display device DSP3 shown in Figure 17 differs from the display device DSP1 shown in Figure 4 in the structure of the bump electrodes 33 and 34. In the case of the display device DSP3 shown in Figure 17, as shown in Figures 18 and 19, portions 33P1 and 33P2 of the conductor portion 33A are arranged to be spaced apart from each other within a single opening 14H1. Therefore, as shown in Figure 19, there is no insulating layer 14 between portions 33P1 and 33P2, and the conductor portion 33B, including the solder, is in contact with the upper surface of the wiring 31 (the surface exposed from the opening 14H1).

[0066] The display device DSP3 and the substrate structure SUB3 provided with the display device DSP3 shown in Figure 17 can be described as follows. The display device DSP3, which is an electronic device, and the substrate structure SUB3 provided with the display device DSP3, include a substrate 10, wiring 31 disposed on the substrate 10, an inorganic insulating layer 14 made of an inorganic material that covers the wiring 31, and bump electrodes 33 connected to the wiring 31 and protruding from the insulating layer 14. The bump electrode 33 includes a conductor portion 33A made of a first metallic material (e.g., copper or a copper alloy) and connected to the wiring 31, and a conductor portion 33B made of solder containing tin and disposed on the conductor portion 33A. As shown in Figure 19, the conductor portion 33A includes a portion 33P1 connected to the wiring 31 in region R1 of an opening 14H1 formed in the insulating layer 14, and a portion 33P2 spaced apart from portion 33P1 and connected to the wiring 31 in region R2 of the opening 14H1.

[0067] In the case of the bump electrode 33 shown in Figures 9 and 10, as described above, the conductor portion 33A is formed by electroplating while the wiring 31 is energized. At this time, the insulating layer 14 is used as a mask, so after forming portions 33P1 and 33P2 of the conductor portion 33A, the insulating layer 14 remains between portions 33P1 and 33P2.

[0068] On the other hand, the bump electrode 33 shown in Figures 18 and 19 is formed by, for example, the following method. That is, a metal film made of copper or a copper alloy is deposited on the insulating layer 14 and the opening 14H1 of the insulating layer 14. Examples of deposition methods include sputtering, CVD (Chemical Vapor Deposition), or panel plating. According to these methods, a metal film of uniform thickness is deposited on the insulating layer 14 and the opening 14H1 of the insulating layer 14. Then, a resist mask is formed to cover the portions corresponding to portions 33P1 and 33P2 shown in Figure 19. Photolithography technology using a photosensitive organic film and an exposure device is used for patterning the resist mask. Next, with portions 33P1 and 33P2 covered by the resist mask, an etching process is performed to remove unnecessary portions of the metal film. Through the above process, the conductive portion 33A shown in Figure 19 is formed. Subsequently, a conductive portion 33B consisting of tin-containing solder is formed by electroplating, similar to the second film formation step described above. By performing the plating process while current is applied to the wiring 31 shown in Figure 19, the conductive portion 33B is selectively formed on the portion of the wiring 31 exposed from the opening 14H1 and on the exposed surface of the conductive portion 33A.

[0069] As shown in Figure 19, the bump electrode 33 obtained through the above process may have a portion of section 33P3 and a portion of section 33P4 integrated into one. However, a gap is formed between the top of section 33P3 and the top of section 33P4.

[0070] In the electronic component mounting process (see Figure 16) for mounting the LED element 20 shown in Figure 17, as already explained, the bump electrode 33 is connected to the anode electrode 20EA of the LED element 20 by melting the conductive portion 33B. In the example shown in Figure 17, the display device DSP3 further includes an electronic component having an anode electrode 20EA connected to the bump electrode 33. The conductive portion 33B of the bump electrode 33 is connected to portion 33P1 and portion 33P2, respectively. At this time, the gap provided between the top of portion 33P1 and the top of portion 33P2 functions as a gas discharge path. Therefore, even in this modified example, it is possible to prevent the formation of a void between the bump electrode 33 and the anode electrode 20EA shown in Figure 17.

[0071] The bump electrode 33 was described above, but the bump electrode 34 shown in Figure 17 has a similar structure to the bump electrode 33 shown in Figure 17.

[0072] Furthermore, in the example shown in Figure 18, each of the sections 33P1 and 33P2 is a linear pattern extending in the X direction in a plan view.

[0073] Furthermore, as shown in Figure 17, the conductive portion 33B of the bump electrode 33 is in contact with the wiring 31 between portions 33P1 and 33P2 of the conductive portion 33A.

[0074] Furthermore, as shown in Figure 17, the display device DSP3 further includes wiring VSL formed on the substrate 10, spaced apart from the wiring 31 and covered by an insulating layer 14, and bump electrodes 34 connected to the wiring VSL and protruding from the insulating layer 14. The bump electrodes 33 and 34 are arranged along the Y direction intersecting the X direction. In other words, each of the portions 33P1 and 33P2 extends in a direction intersecting the arrangement direction of the bump electrodes 33 and 34 in a plan view.

[0075] In the example shown in Figure 18, the solder spreads along the X direction, making it easier to control the range of solder spread in the Y direction. Therefore, even when the distance between the anode electrode 20EA and the cathode electrode 20EK shown in Figure 17 is small, it is possible to prevent short circuits between these electrodes via the solder contained in the conductive portion 33B of the bump electrode 33 and the conductive portion 34B of the bump electrode 34.

[0076] However, although not shown in the illustration, parts 33P1 and 33P2 shown in Figure 18 may extend in the Y direction, similar to the modified example described using Figure 12. If the distance between the anode electrode 20EA and the cathode electrode 20EK shown in Figure 17 is sufficiently maintained, it is possible to prevent short circuits between these electrodes via the solder contained in the conductor portion 34B, even when applying the same modified example as in Figure 12.

[0077] Furthermore, as shown in Figures 20 and 21, the structure of the bump electrode 33 described using Figures 13 to 15 can be applied in combination with the structure of the bump electrode 33 shown in Figures 17 to 19. Figure 20 is a transmitted magnified plan view showing a modified example from Figure 18. Figure 21 is a magnified cross-sectional view along the EE line of Figure 20. Figure 22 is a transmitted magnified plan view showing the state in which the anode electrode of an LED element is connected to the bump electrode shown in Figures 20 and 21.

[0078] Figures 20 and 21 show a modified substrate structure SUB4, which is a variation of the substrate structure SUB3 shown in Figures 18 and 19. Figure 22 also shows a display device DSP4 in which the LED element 20 shown in Figure 17 is mounted on the bump electrode 33 of the substrate structure SUB4 shown in Figures 20 and 21.

[0079] In the case of the bump electrode 33 of the substrate structure SUB4, which is an electronic device shown in Figure 20, the conductor portion 33A further includes a portion 33P5 which is spaced apart from portions 33P1 and 33P2 and connected to the wiring 31 in region R3 of the opening 14H1 (see Figure 21), and a portion 33P6 which is spaced apart from portions 33P1, 33P2, and 33P5 respectively and connected to the wiring 31 in region R4 of the opening 14H1 (see Figure 21).

[0080] As shown in Figure 20, each of sections 33P1, 33P2, 33P5, and 33P6 has a quadrilateral (square) pattern in plan view. The sections of the conductor 33A shown in Figure 20 are squares, which is advantageous because it facilitates etching. However, as a variation, the sections may be circular, similar to those in Figure 13, or elliptical (not shown).

[0081] In this modified example, portions 33P3, 33P4, 33P7, and 33P8 of the conductor portion 33B are connected to each other. However, portions 33P1, 33P2, 33P5, and 33P6 are spaced apart from each other. As a result, gaps are formed between the tops of portions 33P3, 33P4, 33P7, and 33P8 of the conductor portion 33B. These gaps function as a gas discharge path when connecting the conductor portion 33B to the anode electrode 20EA of the LED element 20, as shown in Figure 22.

[0082] Furthermore, as shown in Figure 22, the display device DSP4, which includes the substrate structure SUB4, has an electronic component with an anode electrode 20EA connected to the bump electrode 33. The conductor portion 33B of the anode electrode 20EA is connected to the anode electrode 20EA and is also connected to portions 33P1, 33P2, 33P5, and 33P6 of the conductor portion 33A, respectively.

[0083] Although embodiments and representative modifications have been described above, the technology described above is applicable to various modifications other than those exemplified. For example, the modifications described above may be combined.

[0084] Within the scope of the spirit of the present invention, a person skilled in the art can conceive of various modifications and alterations, and it is understood that such modifications and alterations also fall within the scope of the present invention. For example, any addition, deletion, or design change of components, or addition, omission, or modification of processes, made by a person skilled in the art to the above-described embodiments, is also included within the scope of the present invention, as long as it retains the gist of the present invention. [Industrial applicability]

[0085] This invention can be used in electronic devices such as display devices. [Explanation of symbols]

[0086] 5 Control circuits 6. Drive Circuit 10 circuit boards 10b,10f side 11, 12, 13, 14 Insulating layer 14H1,14H2,14H3,14H4,14H5,14H6 opening 20 LED elements (light-emitting elements, electronic components) 20EA Anode Electrode 20EK Cathode Electrode 31,32,VL,VSL wiring 33, 34, 35 Bump electrodes 33A, 33B, 34A, 34B, 35A, 35B Conductor section 33P1,33P2,33P3,33P4,33P5,33P6,33P7,33P8,34P1,34P2,34P3,34P4 part 33X,35X wall 41 Insulating layer 50 Semiconductor Layers DA display area DSP1,DSP2,DSP3,DSP4 Display device ED drain electrode EG Post Office ES source electrode GL scan signal line Gs control signal LXP Wiring Crossover PFA related areas PIX, PIX1, PIX2 pixels PVS reference potential (fixed potential) R1,R2,R3 area SUB1, SUB2, SUB3, SUB4 substrate structure SW switching element VSG video signal

Claims

1. First circuit board and The first wiring arranged on the first substrate, An inorganic insulating layer made of an inorganic material, comprising a first insulating layer covering the first wiring, A first bump electrode connected to the first wiring and protruding from the first insulating layer, It has, The first bump electrode is A first conductor portion made of a first metal material and connected to the first wiring, A second conductor portion, which consists of solder containing tin and is arranged on the first conductor portion, Includes, The first conductor portion is, A first portion connected to the first wiring in the first region of the first opening formed in the first insulating layer, A second portion is positioned apart from the first portion and connected to the first wiring in the second region of the first opening, Electronic devices, including those mentioned above.

2. In claim 1, An electronic device in which each of the first and second parts is a linear pattern extending in a first direction in a plan view.

3. In claim 2, A second wiring is formed on the first substrate, is arranged to be spaced apart from the first wiring, and is covered by the first insulating layer, A second bump electrode connected to the second wiring and protruding from the first insulating layer, It further possesses, An electronic device in which the first bump electrode and the second bump electrode are arranged along a second direction intersecting the first direction.

4. In claim 1, The electronic component further comprises a first electrode connected to the first bump electrode, An electronic device in which the second conductor portion of the first bump electrode is connected to the first portion and the second portion, respectively.

5. In claim 1, An electronic device in which the second conductor portion of the first bump electrode is in contact with the first wiring between the first and second portions of the first conductor portion.

6. In claim 1, The first conductor portion is, A third portion is positioned apart from the first and second portions and is connected to the first wiring in the third region of the first opening, A fourth portion is positioned apart from each of the first, second, and third portions and is connected to the first wiring in the fourth region of the first opening, An electronic device that further includes the following.

7. In claim 6, The electronic component further comprises a first electrode connected to the first bump electrode, An electronic device in which the second conductor portion of the first bump electrode is connected to the first electrode and is also connected to the first, second, third, and fourth portions, respectively.

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