JP2834069B2 - Chip-in-glass type fluorescent display tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fluorescent display tube, and more particularly to a chip-in-glass type fluorescent display tube having a driving IC built in a vacuum envelope.

[0002]

2. Description of the Related Art Fluorescent display tubes are used in a wide range of fields from home appliances such as audio and VTRs to industrial equipment such as automobile electric components and measuring instruments as display devices which are self-luminous and have excellent visibility. Among them, the chip-in-glass type fluorescent display tube has a driving IC built in the vacuum envelope, so the number of leads led out is reduced, and the overall size is reduced.
It has features that simplicity of module mounting and high reliability by mounting an IC chip in a vacuum are ensured.

The basic structure of a chip-in-glass type fluorescent display tube is as shown in FIG. 10, in which a power supply wiring 10 of an Al thin film is formed on a glass substrate 1 by a sputtering method. Two insulating layers 21 and 22 are formed. Next, the openings of the insulating layers 21 and 22 are filled with conductive graphite, a conductive layer 5 having a shape of a display pixel is formed on the insulating layer, and a phosphor layer 6 is applied.
On the other hand, in the IC chip mounting portion, after the polyimide resin 4 serving as an adhesive is stamped on the insulating layer, the IC chip 9 is mounted thereon, and then heated and left for a certain period of time to cure the resin and fix the IC chip 9 thereto. I do. After that, the pads of the input / output unit of the IC chip and the bonding pads 7 on the substrate are
Bonding is performed by a bonding wire 8. In this case, the insulating layer below the IC chip is the other part of the insulating layer 2
They are not separated from 1 and 22, but are integrated. Thereafter, it is assembled together with the electrode parts such as the grid 11 and the filament 12, and the cover glass 13, sealing is performed by melting the frit glass, and finally, the inside is evacuated and sealed to finish and complete.

Here, the following proposal has been made regarding the shape of the insulating layer in the IC chip mounting portion. For example,
In Japanese Patent Application Laid-Open No. 5-74348, a power supply wiring of Al is formed on a glass substrate 1 as shown in FIG. 11, and two insulating layers 51 are applied by screen printing. At this time, two types of screens are used to provide a first opening 41 in the mounting portion of the IC chip 9 of the first insulating layer, and a second opening 41 for covering the first insulating layer.
The second opening 42 is provided in the layer insulating layer. First layer and second layer
Since the thickness of each of the insulating layers is 20 μm, the depth of the first opening is 40 μm, and the depth of the second opening is 20 μm. Also, the size of the first opening 41 is such that at least two sides are smaller than the corresponding sides of the IC chip 9,
The second opening 42 has a length in the short side direction larger than the length of the IC chip 9 by about 0.1 μm, and gives a vibration when the IC chip 9 is mounted in the long side direction so that the IC chip 9 and the polyimide resin In order to make 4 compatible, it is necessary to increase the amplitude by the amplitude. The wire bonding is performed with the IC chip 9 mounted and the adhesiveness of the polyimide resin 4 and the temporary fixing by the second opening 42.

Japanese Unexamined Patent Application Publication No. 5-89805 discloses FIG.
As shown in (a) and (b), the second groove 32 of the insulating layer 51 is formed.
Is coated with a die bonding material 61, on which the IC chip 9 is mounted so as to fit in the first groove 31. Also, in FIGS. 12C and 12D, the second groove 32 2
The sides are larger than the chip size, and the remaining two sides are smaller than the chip size, and the first groove has a structure in which the first groove has a correspondingly larger portion.

[0006] These two proposals are based on the fact that in a two-layer insulating layer below an IC chip mounting portion of a chip-in-glass type fluorescent display tube, the first insulating layer on the substrate side has one of the IC chip sides. , The second insulating layer forms a larger opening, and is filled with a die bonding material to fix the IC chip. In any of the above configurations, no insulating layer corresponding to the bonding surface is left below the IC chip mounting portion.

[0007]

In the prior art, an IC
A crack reaching the glass substrate occurs on the joint surface between the insulating layer of the chip mounting portion and the polyimide resin layer used as the adhesive for the IC chip, and the Al power supply wiring passing under the insulating layer is broken. The reason is that due to the heat process such as the sealing process in the manufacturing process and the heat generated by the IC chip during the operation of the chip glass type fluorescent display tube, the difference in the thermal expansion coefficient between the IC chip, the polyimide resin, the insulating layer and the glass substrate causes This is because distortion occurs.

According to the present invention, in the chip-in-glass type fluorescent display tube, one of the causes of the malfunction is a substrate crack reaching the power supply wiring of Al passing under the IC chip mounting portion.
The purpose is to eliminate this.

[0009]

According to the present invention, there is provided a power supply wiring formed on a glass substrate and an IC which covers the power supply wiring.
The first insulating layer on the glass substrate side having an opening in the bonding pad portion around the chip mounting portion and the second insulating layer formed thereon
In a fluorescent display tube in which a second insulating layer and an adhesive layer for bonding an IC chip to the insulating layer are formed, and a driving IC chip is mounted on the adhesive layer, a second IC chip mounting portion is provided.
It is characterized in that a groove is formed to penetrate the insulating layer of the layer and surround the IC chip, so that the insulating layer of the IC chip mounting portion is separated from the others in an island shape. Note that the first insulating layer may be thicker than the second insulating layer. Further, even if a groove is formed in the second insulating layer, a certain effect can be obtained.

The insulating layer immediately below the IC mounting portion is separated from the others in an island shape. By doing so, the heat history in the manufacturing process and the heat generated by the IC chip during the operation of the chip-in-glass cause distortion due to stress caused by the difference in the coefficient of thermal expansion between the IC chip, the adhesive, the insulating layer, and the glass substrate. Since the insulating layer is separated from the others in an island shape, the amount of displacement due to the distortion of the insulating layer below the IC chip can be reduced, and disconnection of the Al power supply wiring passing under the insulating layer on the glass substrate can be prevented. Can be prevented.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the drawings. FIG. 1 is a partially cutaway plan view of the first embodiment of the present invention, FIG. 2 is a partially enlarged plan view of the IC chip mounting portion of FIG. 1, and FIG. 3A is AA 'of FIG. 3 (b) is a sectional view taken along line BB 'of FIG. 2, and FIG.
It is a perspective view of an opening of an insulating layer of a 1st embodiment before chip mounting.

In the first embodiment, as shown in FIGS. 1 to 4, on a glass substrate 1 on the surface of which a power supply wiring of Al is formed by screen printing, a glass substrate 1 having a predetermined thickness is formed.
A layered insulating layer is applied. At this time, two types of screens were used, and the glass substrate 1 immediately below the IC chip 9 mounting portion was used.
Is formed, and a second groove 32 is formed thereon with a step. The thickness of each insulating layer is about 10 μm ×
Since 2 = 20 μm, the depth of the first groove 31 is 20 μm, and the depth of the second groove 32 is 10 μm. The width of the groove is about 0.8 mm. The length and width of the island-shaped first insulating layer 21 on the IC chip 9 mounting portion are larger than the IC chip 9 by about 0.2 mm, and the length and width of the second insulating layer 22 are the first layer. It is smaller than the insulating layer by about 0.1 mm.

The two insulating layers include a phosphor layer 6 and an Al layer.
A through-hole for establishing conduction with the power supply wiring is provided, and a conduction layer 5 for conduction is applied to the through-hole. And
A graphite layer having the shape of a display pixel is provided on the second insulating layer 22 via a conductive layer 5 for conduction, and a phosphor layer 6 is formed thereon. Further, a polyimide resin 4 used as an adhesive is applied to the upper part of the island-shaped insulating layer immediately below the mounting portion of the IC chip 9, and the IC chip 9 is mounted thereon, and is heated and cured for a certain time to fix the IC chip 9. I do. In this state, the bonding pad 7 on the substrate and the IC
The connection leads on the chip 9 side are connected by bonding wires 8 by a wire bonder. Thereafter, they are combined together with an electrode component such as a filament, a cover glass or the like, and sealing is performed by melting the frit glass. Then, the inside is evacuated and sealed, finished and completed. As described above, in the present embodiment, since the insulating layer immediately below the IC chip mounting portion is separated from other portions in an island shape, the manufacturing process and the IC
The amount of distortion due to thermal stress between the glass substrate and the insulating layer due to heat during operation can be reduced, and generation of cracks and the like can be prevented.

FIG. 5 is a sectional view showing a second embodiment of the present invention. The manufacturing method of the second embodiment is almost the same as that of the first embodiment, except that the depth of the first groove 31 is about 15 μm. This is because the first insulating layer 21
Has the advantages of increasing the thickness of the first embodiment compared to the first embodiment, increasing the heat capacity, and alleviating the stress due to heat.

FIG. 6 is a partially enlarged plan view of an IC chip mounting portion according to a third embodiment of the present invention, and FIG.
FIG. 7B is a cross-sectional view taken along the line DD ′ of FIG. 6, and FIG. 8 is a perspective view of the opening of the insulating layer of the third embodiment before mounting the IC chip. It is. The manufacturing method of the third embodiment is almost the same as that of the first embodiment,
Regarding the insulating layer immediately below the chip 9 mounting portion, the second insulating layer 2
Only the second insulating layer 21 is separated from the others in an island shape, and the first insulating layer 21 in the opening of the second insulating layer 22 is also provided with a heat dissipation function.
The stress due to thermal expansion is absorbed by the second insulating layer 22.

FIG. 9 is a sectional view showing a fourth embodiment of the present invention. The manufacturing method of the fourth embodiment is the same as that of the first embodiment. As a modification of the second and third embodiments, the depth of the first groove as shown in FIG. 15 μm
By increasing the thickness of the first insulating layer 21, the heat capacity is increased, and in addition, only the second insulating layer 22 is separated from the others with respect to the insulating layer immediately below the IC chip 9 mounting portion. To give the opening of the second insulating layer 22 a heat radiation function,
Absorb stress due to thermal expansion.

[0017]

As described above, according to the present invention,
Breakage of the power supply wiring of Al under the insulating layer of the IC chip mounting portion can be prevented. The reason is that the insulating layer of the IC chip mounting portion is separated from the others in an island shape, so that the heat history in the manufacturing process and the heat between the insulating layers of the glass substrate due to the heat generated by the IC during the operation of the chip-in-glass type fluorescent display tube. This is because the amount of distortion due to stress can be reduced.

[Brief description of the drawings]

FIG. 1 is a partially cutaway plan view of a first embodiment of the present invention.

FIG. 2 is a partially enlarged plan view of an IC chip mounting section of FIG. 1;

FIG. 3A is a sectional view taken along line AA ′ of FIG. 2;
FIG. 3 is a sectional view taken along line BB ′ of FIG. 2.

FIG. 4 is a perspective view of an opening of an insulating layer according to the first embodiment before mounting an IC chip.

FIG. 5 is a sectional view of a second embodiment of the present invention.

FIG. 6 is a partially enlarged view of an IC chip mounting portion according to a third embodiment of the present invention.

7A is a cross-sectional view taken along line CC ′ of FIG. 6, and FIG. 7B is a cross-sectional view taken along line DD ′ of FIG.

FIG. 8 is a perspective view of an opening of an insulating layer according to the third embodiment before mounting an IC chip.

FIG. 9 is a sectional view of a fourth embodiment of the present invention.

FIG. 10 is an overall configuration diagram of a conventional chip-in-glass type fluorescent display tube.

FIG. 11 is a cross-sectional view of a conventional example shown in Japanese Patent Application Laid-Open No. 5-74348.

FIGS. 12A to 12D are views showing a conventional example disclosed in JP-A-5-89805.

DESCRIPTION OF SYMBOLS 1 Glass substrate 4 Polyimide resin 5 Conductive layer 6 Phosphor layer 7 Bonding pad 8 Bonding wire 9 IC chip 21 First layer insulating layer 22 Second layer insulating layer 31 First groove 32 Second groove

Claims (3)

(57) [Claims] A power supply wiring formed on a glass substrate;
A first insulating layer on the glass substrate side having an opening in a bonding pad portion around the IC chip mounting portion and a second insulating layer formed thereon, which covers the power supply wiring, and an IC chip is bonded to the insulating layer. An adhesive layer to be formed is formed, and a chip implanter on which a driving IC chip is mounted is formed on the adhesive layer.
In the display type fluorescent display tube, the bonding pad
A groove is formed to penetrate through the two insulating layers of the IC chip mounting portion so as to include the opening and surround the IC chip, so that the insulating layer of the IC chip mounting portion is separated from the others in an island shape. Characteristic chip-in-glass type fluorescent display tube. 2. The chip-in-glass type fluorescent display tube according to claim 1, wherein the first insulating layer has a thickness greater than that of the second insulating layer. 3. A power supply wiring formed on a glass substrate,
A first insulating layer on the glass substrate side having an opening in a bonding pad portion around the IC chip mounting portion and a second insulating layer formed thereon, which covers the power supply wiring, and an IC chip is bonded to the insulating layer. An adhesive layer to be formed is formed, and a chip implanter on which a driving IC chip is mounted is formed on the adhesive layer.
In the display type fluorescent display tube, the bonding pad
A groove surrounding the IC chip is formed only in the second insulating layer of the IC chip mounting portion so as to include the opening, and the second insulating layer of the IC chip mounting portion is separated from the others in an island shape. A chip-in-glass type fluorescent display tube characterized by the above-mentioned.