KR940007874B1 - Fluorescent character display tube - Google Patents

Abstract

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Description

Fluorescent light tube

1 is a plan view of a fluorescent display tube of the present invention.

2 is a cross-sectional view of the first embodiment of the present invention.

3 is an enlarged sectional view of an essential part of the first embodiment of the present invention.

4 is a sectional view of a second embodiment of the present invention.

5 is a plan view of an essential part of a second embodiment of the present invention.

6 is a plan view in which a part of a fluorescent display tube of a conventional COG structure is cut out;

7 is a cross-sectional view taken along the line A-A of FIG.

* Explanation of symbols for main parts of the drawings

1: glass substrate 2a: thin film wiring conductor

3: insulation layer 4: phosphor layer

10 thick film conductor 11 metal ball bump (solder ball bump)

12 IC chip 14 thin film connection part

15 thick-film connection 16 thick-film wiring conductor

The present invention relates to a fluorescent display tube. In particular, the glass substrate of the fluorescent display tube is extended from an external device, and the IC chip for driving the fluorescent display tube is disposed in the extension portion. The present invention relates to a fluorescent display tube having a structure of "Chip on Glass" (hereinafter referred to as COG).

In recent years, fluorescent display tubes are used not only for audio products and home appliances but also for vehicle panel panels, and are called vehicle fluorescent display tubes.

Since the vehicle fluorescent display tube is limited in the place of attachment, a fluorescent display tube is provided in which the driving circuit of the fluorescent display tube is housed in an IC chip and the IC chip is integrally disposed on the fluorescent display tube. The chip placed in the vacuum envelope of the fluorescent display tube is called chip, in glass (C, I, G), and the chip placed outside the vacuum envelope is called C, O, G. have. Fluorescent display tubes of type C, O, and G can be placed after the sealing process of fluorescent display tubes in comparison with the type C, I, and G. Therefore, they pass through the IC chip at a high temperature of 400 to 500 ° C at the time of sealing. It does not need to be used, and it is possible to replace the IC chip if it is damaged.

In addition, since a fluorescent display tube for a vehicle is attached near an engine and has a high ambient temperature and vibration, it is also required that the connection strength between the IC chip and the wiring conductor is strong.

However, the conventional C, O, and G fluorescent display tubes are known from Japanese Patent Application Laid-Open No. 60-163079 having a structure as shown in the cutaway plan view of the principal part of FIG. 6 and the cut cross-sectional view taken along the line A-A of FIG. In this conventional example, 21 is a glass substrate, and the anode substrate 21A of the fluorescent display tube and the IC chip attaching substrate 21B are integrated. On the positive electrode substrate 21B, a wiring conductor 22 made of an aluminum thin film is connected from the positive electrode substrate 21A to the chip attachment substrate 21B. On the wiring conductor 22, the insulating layer 23 and the positive electrode are formed. The conductor 24 and the phosphor layer 25 are structures of a fluorescent display tube in which layer layers are stacked.

The anode conductor 24 is constituted by a phosphor layer 25, and a plurality of anode segments are arranged to form a cathode display portion 26 displaying a pattern such as a number.

A mesh control electrode 27 and a filament-shaped cathode 28 are disposed above the anode display unit 26. In addition, a box-shaped container portion 29 is disposed at the periphery of the anode substrate 21 so as to cover the electrodes such as the anode display portion 26, the control electrode 27, the cathode 28, and the like, and is formed of frit glass. It seals airtightly and the envelope is formed.

The wiring conductor 22 extends from the envelope to the outside chip attaching substrate 21B, and a bonding pad portion 30 made of Ag paste containing no glass powder is disposed at its tip. The IC chip 31 is adhesively fixed to the IC attachment substrate 1B by the epoxy adhesive 32. Then, wire bonding is performed between the Al electrode on the IC chip and the pad portion 30 using, for example, Au wire 33. Furthermore, the protective film 34 is coated by silicon- or epoxy-based plastic on the IC chip. However, a fluorescent display tube having a C, O, and G structure by conventional wire bonding has the following problems.

(1) The bonding method of the IC chip of the wire bonding method is a place where the arrangement space of the wire and the capillary of the bonding machine are inserted around the IC chip in order to bond the IC and the bonding pad on the substrate by the bonding machine. As shown in the plan view of Fig. 6, a margin is required, and the substrate is extended in the direction of the long side of the rectangular envelope to form a wide extension portion, and an IC chip is attached to this extension portion. Therefore, the whole fluorescent display tube becomes large and has a problem in raising mounting density.

(2) When the fluorescent display tube is turned on, the anode heats up and the glass substrate is heated. This heat is also retained in the organic adhesive for fixing the IC chip and the resin film being protected. Since all of the above adhesive materials and protective films are synthetic resins, the adhesive strength becomes weak after a long time, the bonding of the wires is peeled off, and there is a problem that the reliability is insufficient.

(3) Al wiring in the fluorescent display tube is generally 50 µm wide, especially in the case of the C, O, G type having a high wiring density, 30 µm wide. In addition, the bonding pad by Ag paste had a width of 200 to 300 µm as a thick film to be deposited by screen printing. Therefore, although Ag bonding pad portions are stacked on the 30-micrometer Al wiring at 200-300 micrometers, since Al, which is a material of Al wiring, is very easy to oxidize, the bonding pad portion of Ag can be formed after the Al wiring is formed. There was also a problem in that the surface of Al was oxidized until good electrical conduction was obtained between Al and Ag.

(4) Furthermore, in the part where the Al thin film wiring overlaps with the Ag thick film, when the temperature of 400 to 600 ° C. is applied in the manufacturing process of the fluorescent display tube, Al diffuses into the Ag, causing the Al connection to break. Had also.

An object of the present invention is to provide a fluorescent display tube having a C, O, and G structure that solves the above-mentioned problems. In order to achieve the above object, the configuration of the present invention is a fluorescent display tube in which the glass substrate of the fluorescent display tube extends from the envelope, and the fluorescent display tube driving unit by the IC chip is disposed in the extension portion. The tube driving unit is a wiring conductor made of a conductive thin film extending to an extension of the glass substrate, a thick film conductor made of a conductive paste disposed in connection with the wiring conductor, and an IC fixed by metal ball bumps on the thick film conductor. It is characterized by having a chip.

Moreover, the said wiring conductor is formed by Al thin film, It is characterized by the above-mentioned.

In addition, the thick film conductor may be made of only Ag, or a conductive material containing Pt or Pd containing Ag as a main component, and glass solder.

In addition, the thick film conductor is characterized by having a dot shape laminated on the top surface of the distal end of the wiring conductor.

In addition, the thick film conductor has a thick film wiring portion adjacent to the front end of the thin film wiring conductor, and the metal balls and bumps disposed on the IC chip are fixed to the front end of the thick film wiring portion.

Further, a thin film connecting portion having a wider width than the thin film wiring conductor is disposed at the tip of the thin film wiring conductor, and the thick film conductor connected to the thin film connecting portion has a thick film connecting portion having a width smaller than that of the thin film connecting portion.

Furthermore, the present invention extends the glass substrate of the fluorescent display tube from the envelope, wherein the fluorescent display tube driving portion is provided with an IC chip in the extension portion, and the fluorescent display tube driving portion extends the glass substrate. A thin film wiring conductor made of an Al thin film extending in an enclosure in a portion, a thick film wiring conductor made of a conductive paste arranged to connect to the thin film wiring conductor, a thick film conductor other than the tip of the thick film wiring conductor, and the thin film wiring. And an IC chip in which solder ball bumps are fixed on the thick film wiring conductor.

According to the present invention, a thick film conductor is provided at the tip of a thin film wiring conductor, and the IC chip having the metal ball bump of the IC is fixed on the surface thereof, that is, the IC chip is fixed on the substrate by fusion welding or the like in a flip chip method. Therefore, compared with the conventional wire bonding method, the connection strength is high, the reliability is high, the environmental temperature to light up, and works well for vehicles with high vibration.

In addition, a wide thin film connecting portion is disposed at the tip of the Al thin film wiring conductor, and a thick film connecting portion which is slightly narrower than the thin film connecting portion is also disposed at the base of the Ag thick film conductor. Since there is much Al remaining, the line is not broken.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Example 1

1 to 3, 1 is a glass substrate, and on this glass substrate, a conductive thin film is deposited on the entire surface by the sputtering method, and the pattern of the wiring conductor 2a and the anode conductor 2b is formed by photolithography. Form. In this embodiment, the case where the conductive thin film is an Al thin film will be described.

The insulating layer 3 is laminated on the glass substrate except for the anode conductor 2b. The phosphor layer 4 is deposited on the anode conductor 2b. On the upper side of the phosphor layer 4, a mesh-shaped control electrode 5 and a filamentary cathode 6 are arranged. When the box-shaped container portion 9 including the side plate 7 and the front plate 8 is sealed on the glass substrate 1 so as to cover the electrode, a fluorescent display tube is formed.

The glass substrate 1 extends on the short side of the container portion 9, and the wiring conductor 2a extends from the above-described fluorescent display tube to the metal ball / bump of the IC chip described later. The pattern is formed so as to correspond. The width of the wiring conductor 2a is 100 µm or more, and a dot-shaped thick film conductor 10 is formed at the tip thereof.

The thick film conductor 10 is formed by mixing a low melting point glass solder into a conductive powder containing Ag as a main component and a small amount of Pd, and wiring the conductive paste paste-formed by a vehicle by screen printing. It is formed at the tip of the conductor 2a. The conductive powder may be Ag alone or Ag-Pt in addition to Ag-Pd described above. In addition, an insulating layer 3 for protection is formed on the wiring conductor 2a by screen printing. A thick film such as the insulating layer 3 or the thick film conductor 10 is deposited by screen printing, and then fired in a calcination furnace in an oxidizing atmosphere to evaporate the vehicle and adhere to the substrate.

Next, the IC chip 12 on which the metal balls and bumps 11 are arranged is heat-fixed onto the film conductor 10 after the above. There are various kinds of materials for the metal balls and bumps 11, such as Au, Ag, Ni, and Cu soldering. However, in this embodiment, since the glass substrates cannot be heated at a high temperature, the solder balls and bumps 11 using solder metals are used. IC chip is arranged. Therefore, by heating at 180 to 280 ° C, the IC chip can be reliably fused to the thick conductor 10. Furthermore, the synthetic resin as the protective film 13 is molded around the IC chip to complete the fluorescent display tube.

Example 2

Although Example 1 is applied to the fluorescent display tube in which the thin film wiring conductor of an extension part is acquired to some extent, Example 2 is a fluorescent display tube when a thin film wiring conductor is 50 micrometers or less. Since the configuration of the fluorescent display tube in the envelope is the same as that of the first embodiment, description thereof is omitted and only the attachment portion of the IC chip is described. The Al thin film wiring conductor 2a extending in the envelope has a line width of 50 µm or less and can increase the wiring packaging density.

At the tip of the Al thin film wiring conductor 2a, as shown in FIG. 5, a rectangular thin film connecting portion 14 having a width of about 150 to 200 mu m is disposed in the Al thin film wiring conductor continuously in the Al thin film wiring conductor. It is. On the upper surface of the Al thin film connecting portion 14, a thick thin connecting portion 15, which is shorter in width and shorter than the Al thin film connecting portion 14, is laminated at regular intervals from the connecting portion of the thin film wiring 2a. The thick film wiring conductor 16 is arrange | positioned in connection with this thick film connection part 15, and the soldering ball bump 11 of the IC chip 12 is fixed to the front-end | tip. The thick film connection part 15 and the thick film wiring conductor 16 form a conductive layer on the surface by baking at 400-500 degreeC, after depositing the electrically conductive paste like Example 1 with the screen printing method.

Moreover, the insulating layer 3 laminated | stacked and arrange | positioned on the thin film wiring conductor, the thin film connection part, the thick film connection part, and the thick film wiring conductor is comprised from two layers, and strengthens protection more. Moreover, the 2nd insulating layer is made outward rather than the 1st layer so that resin for the overcoat mentioned later may flow easily under the IC chip.

In this embodiment, since the connection portion between the Al thin film and the Ag thick film is in contact with the wide surface and the surface in the wiring conductor 2a, Al will diffuse in the Ag even if heated in the manufacturing process of the fluorescent display tube. Since the side is large in area, it is possible to reliably conduct without disconnection.

Further, since the Ag thick film is deposited by screen printing, the accuracy is not very high. However, since the Ag thick film connecting portion is smaller in area than the Al thin film connecting portion, the two films are in contact even if there is a slight printing misalignment.

Further, by arranging the connection portion between the Al thin film and the Ag thick film in the envelope of the fluorescent display tube, the reliability of conductivity can be improved.

Next, the solder balls and bumps of the IC chip are heated while being placed on the thick film wiring conductor to melt the solder, and fuse them to Ag on the surface of the thick film wiring conductor. Finally, the synthetic resin is used as the protective film 13 to overcoat around the IC chip.

As described above, in the fluorescent display tube having the C, O, and G structure, the thick film conductor is provided at the pressure of the thin film wiring conductor, and the solder balls and bumps of the IC of the thick film conductor are fixed. Has an effect.

(1) Since the mounting area of the IC chip is smaller than that of the conventional wire bonding method, the chip attaching portion can be made smaller than the conventional one, and the package size of the fluorescent display tube can be made smaller.

(2) Since the thin film connection part was provided at the end of the Al thin film bastion and connected to the Ag thick film conductor, disconnection caused by diffusion of Al was eliminated, and good electrical conduction was obtained between the Al thin film wiring and the Ag thick film conductor. .

(3) By fusion bonding the IC chip with the solder thick film and the Ag thick film conductor, it is possible to provide a fluorescent display tube which is a connection mechanism that is also resistant to heat and vibration and has excellent electrical reliability.

(4) Since the wide connection part of both the connection part of Al thin film and Ag thick film was provided, the conduction defect by the printing position shift of Ag thick film paste will be eliminated.

Claims (8)

A fluorescent display tube in which a glass substrate of a fluorescent display tube extends from a container portion, and a fluorescent display tube driving portion for an IC chip is disposed in the extension portion, wherein the fluorescent display tube driving portion is formed in an extension portion of the glass substrate. A thin film conductor made of a thin film wiring conductor, a thick film conductor made of a conductive paste disposed in connection with the wiring conductor, and an IC chip fixed by metal balls and bumps on the thick film conductor. A fluorescent display tube according to claim 1, wherein said wiring conductor is formed of an Al thin film. The fluorescent display tube according to claim 1, wherein the thick film conductor comprises Ag only or a conductive material containing Pt or Pd mixed with Ag as a main component and glass solder. The fluorescent display tube according to claim 1, wherein the thick film conductor has a thick film wiring portion connected to a tip of the thin film wiring conductor, and a metal ball bump is disposed on the IC chip at the tip of the thick film wiring portion. The thin film connecting portion according to claim 1, 2, 3 or 4, wherein a thin film connecting portion having a wider width than the thin film wiring conductor is disposed at the tip of the thin film wiring conductor, and the thick film conductor connected to the thin film connecting portion is the thin film connecting portion. A fluorescent display tube, characterized in that it has a smaller thickness connection portion of a smaller width. In a fluorescent display tube in which a glass substrate of a fluorescent display tube is extended from an enclosure, and a fluorescent display tube driving portion by an IC chip is disposed in the extension portion, the fluorescent display tube driving portion is formed in an envelope in an extension portion of the glass substrate. A thin film wiring conductor made of an Al thin film extended in the above, a thick film wiring conductor by a conductive paste disposed to connect to the thin film wiring conductor, a thick film wiring conductor other than the tip of the thick film wiring conductor, and the thin film wiring conductor A fluorescent display tube having an insulating layer and an IC chip having solder balls and bumps fixed on the thick film wiring conductor. 7. The fluorescent display tube according to claim 6, wherein the thick-film wiring conductor includes Ag or a conductive material containing Pt or Pd mixed with Ag as a main component and a low melting point glass solder. 8. The thin film connecting portion, wherein the tip of the Al thin film wiring conductor is formed wider than the wiring, and a wider width than the thick film wiring and a narrower width than the thin film wiring at the base of the thick film wiring conductor. A fluorescent display tube comprising a thick film connecting portion laminated.

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