JPH04291388A - Fluorescent display device - Google Patents

Abstract

PURPOSE:To form a bump for IC packaging which is durable to a heat treatment process on the substrate of the fluorescent display device which has an electric field radiation type cathode. CONSTITUTION:The electric field radiation type cathode 11 formed on the substrate is covered with a container part 15 and faces a display part 19. On the substrate 2 outside an enclosure 16, the bump 12 where an IC 21 is packaged is formed of the same material in the same process with the emitter 10 of the electric field radiation cathode 11.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorescent display device which uses a field emission cathode as an electron source and is provided with terminals for mounting a driving IC.

0002

2. Description of the Related Art Conventionally, the following methods (1) to (4) are known as methods for mounting ICs on a substrate. ■Wire bonding method, in which the IC is glued onto the substrate and the electrodes of the IC and the electrodes on the substrate are connected using bonding wires. ■ TAB (Tape Automated
Bonding method. ■Form solder bumps on the IC terminals and place them on the board,
A flip chip bonding method in which the solder bumps are melted and mounted by passing them through a reflow oven. ■A method in which bumps such as Au are formed on the IC and then mounted on the electrodes of the board using conductive adhesive. ■Microbump method that applies pressure to the IC and substrate, hardens the photocurable resin under that condition, fixes the IC, and maintains the connection between the IC terminal and the electrode.

0003

[Problems to be Solved by the Invention] However, in fluorescent display devices, due to structural reasons, etc., a driving IC is mounted on a substrate constituting the envelope of the fluorescent display device, and the wiring on the substrate is There are cases where you want to connect the IC directly. In fluorescent display devices, the electrodes on the substrate constituting the envelope are generally made of Al, Ag, ITO, etc.
The surface is easily oxidized and an insulating film is easily formed. Furthermore, ITO has a high surface resistance. Furthermore, Ag is prone to migration and cannot maintain insulation between wirings.

[0004] Therefore, when an IC is mounted on a substrate of a fluorescent display device using the above-mentioned methods ① to ②, the surface of the electrodes on the substrate made of the above-mentioned materials must be plated. . For example, it is necessary to ensure the connection and conduction between the electrode and the IC terminal by forming a single layer of Au on the electrode or forming an Au layer after forming the Ni layer.

However, the adhesion strength of the plating layer to the electrode is not so high. Fluorescent display devices always include a heat treatment process during the manufacturing process. Therefore,
If the electrodes of the substrate are plated as described above before this heat treatment step, the plating layer will be subjected to force due to the difference in thermal expansion coefficient during the heat treatment step, and will easily peel off from the interface.

[0006] Furthermore, when the plating treatment is performed after the fluorescent display device is completed, there is a problem in that the lead component of the sealing glass that has undergone the heat treatment process reacts with the plating solution, causing the sealing glass to melt.

As described above, in fluorescent display tubes, it is difficult to perform plating on the wiring on the substrate, and there is a problem that ICs cannot be mounted on the substrate using the methods (1) to (4) described above.

[0008]

Means for Solving the Problems In order to solve the above problems, a fluorescent display device of the present invention includes a substrate, a field emission type cathode formed on the substrate, and a display facing the field emission type cathode. The device includes a container portion provided on the substrate, and a bump for IC mounting formed on the substrate using the same material as the electrode of the field emission type cathode.

[0009]

[Operation] When forming a field emission type cathode on a substrate, bumps for IC mounting can be simultaneously formed using the same material as the electrode of the field emission type cathode.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of a fluorescent display device 1 which is an embodiment of the present invention will be explained according to the manufacturing steps shown in FIGS. 1 to 7. The fluorescent display device 1 of this embodiment has a cone-shaped emitter 1
A Spindt type field emission type cathode 11 having 0 is used as an electron source. Bumps 12 made of the same material as the emitter 10 are provided on the substrate 2 forming a part of the envelope 16, so that the IC 21 can be mounted on the substrate 2 outside the envelope 16.

First, as shown in FIG. 1, a wiring conductor 3 made of Al, ITO, etc. is formed on the upper surface of a substrate 2 made of glass, silicon, or the like. The wiring conductor 3 is connected to an emitter 10 of a field emission type cathode 11 and a driving IC 21, which will be described later. Then, a resistive layer 4 is formed on this wiring conductor 3 except for the portion where the IC 21 is mounted.

As shown in FIG. 2, an insulating layer 5 is formed covering the resistance layer 4, wiring conductor 3, and substrate 2. As shown in FIG.

As shown in FIG. 3, a gate 8 of a field emission type cathode 11 is formed on the insulating layer 5 corresponding to the resistive layer 4.
A gate layer 6 is formed by vapor deposition of Nb.

As shown in FIG. 4, a resist layer 7 is formed to cover the area except for the opening of the gate 8 and the area where the bumps 12 are to be formed. This resist layer 7 includes the gate layer 6
It is obtained by applying a resist over the entire upper surface of the insulating layer 5, exposing it to light in a predetermined pattern, and developing it.

The insulating layer 5 and gate layer 6 are selectively etched through openings in a predetermined pattern provided in the resist layer 7. As a result, a gate 8 having an opening is formed, and the wiring conductor 3 of the IC mounting portion is exposed. After etching, the resist layer 7 is removed and
As shown in FIG.
A peeling layer 9 consisting of the following is formed. The peeling layer 9 is formed, for example, by a method of vapor depositing Al from diagonally above the substrate 2, and Al is deposited inside the gate 8 and on the exposed wiring conductor 3.
Make sure that l does not get attached.

As shown in FIG. 6, Mo is deposited on the entire surface of the substrate 2, and a cone-shaped emitter 10 is formed on the resistance layer 4 in the gate 8 to constitute a field emission type cathode 11. Bumps 12 are formed on the wiring conductor 3. In this way, the emitter 10 and the bump 1 are formed by vapor deposition of Mo.
2 is formed in the same process, unnecessary Mo deposited on the release layer 9 is removed together with the release layer 9.

As shown in FIG. 7, the front plate 13 and the side plate 1
4 is sealed and fixed to the upper surface of the substrate 2 to form a box-shaped envelope 16 in which the field emission cathode 11 is housed. On the inner surface of the front panel 13 is a display section 19 in which a phosphor layer 18 is adhered to a translucent anode conductor 17.
is formed, and the display section 19 faces the field emission cathode 11.

In this embodiment, the bump 12 is connected to the envelope 1.
It is outside of 6. An IC 21 is mounted on this bump 12 via solder or a conductive adhesive 20. Board 2 and IC21
A resin 22 is sealed between them. This IC 21 is connected to the field emission type cathode 11 in the envelope 16 via the bump 12 and the wiring conductor 3, and can give a drive signal to the field emission type cathode 11.

According to this embodiment, in the step of forming the emitter 10 of the field emission type cathode 11, the bump 12 for mounting the IC 21 can also be formed at the same time. Therefore, there is no need to provide a plating process on the wiring for connecting the electrodes on the IC and the wiring as in the conventional method, and the electrodes for connecting to the electrodes on the IC can be formed in fewer steps. Further, since the bumps 12 are formed by vapor deposition, the adhesion strength of the film is greater than that of plating, and the bumps 12 will not peel off from the wiring conductor 3 even after undergoing a heat treatment step essential for manufacturing a fluorescent display device. In addition, the mounting of the IC 21 on the board 2 is as described above.
This can be done by the methods of ~ (), but since plating is not required, the sealing glass of the container portion 15 sealed to the substrate 2 will not be melted by the plating solution.

In the embodiment described above, the emitter 10
Although the bumps 12 are formed of the same material as the emitter 10 at the same time as the gate layer 6 is formed, the bumps may be formed of the same material as the gate 8 at the same time as the gate layer 6 is formed.

In this embodiment, the bumps 12 are provided on the substrate 2 outside the envelope 16, but the bumps are formed on the substrate 2 inside the envelope 16 and the IC 21 is placed inside the envelope 16. It may be stored and mounted. Further, as a type of field emission cathode, a structure in which the emitter is formed in a comb-like shape and the gate and the emitter are formed on the same plane can also be applied.

[0022]

According to the present invention, the bumps for IC mounting are formed on the substrate using the same material as the electrode of the field emission type cathode, so that a fluorescent display device equipped with bumps with high adhesion strength can be manufactured easily during the process. I was able to get a child without having to increase the amount.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one step in the manufacturing process of a fluorescent display device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing one step in the manufacturing process of a fluorescent display device according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing one step in the manufacturing process of a fluorescent display device according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view showing one step in the manufacturing process of a fluorescent display device according to an embodiment of the present invention.

FIG. 5 is a cross-sectional view showing one step in the manufacturing process of a fluorescent display device according to an embodiment of the present invention.

FIG. 6 is a sectional view showing one step in the manufacturing process of a fluorescent display device according to an embodiment of the present invention.

FIG. 7 is a cross-sectional view showing one step in the manufacturing process of a fluorescent display device according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1... Fluorescent display device, 2... Substrate, 8... Gate which is an electrode of a field emission type cathode, 10... Emitter which is an electrode of a field emission type cathode, 11... Field emission type cathode, 12... Bump, 15...
Container section, 19...display section.

Claims (1)

[Claims] 1. A substrate, a field emission cathode formed on the substrate, a container section provided on the substrate and including a display section facing the field emission cathode, and an electrode of the field emission cathode. and bumps for IC mounting formed on the substrate using the same material.