JPS59224036A - Fluorescent character display tube - Google Patents

Abstract

PURPOSE:To secure a fluorescent character display tube that enjoys a long span of service life, by installing a cover, which protect a semiconductor device from ionic impurities, on a base plate of a driving circuit part, in case of the fluorescent character display tube being solidly formed together with a display part and the driving circuit part as one body. CONSTITUTION:Plural wiring films 2, an insulating film 3, a segment electrode 4 and a phosphor layer 5 are all installed on the top of a glass base plate 1A whereby an anode display part is formed up by the electrode 4. On the display part, figures of plural digits set up in parallel with plural digits are selectively displayed by a driving circuit part 14. A display tube before bonding an LSI chip 15 of the circuit 14 is put several tens into a high frequency spatter device whereby a top coat 30 of Al2O3 is formed on the base plate via a mask, while the top coat 30 is installed in a position where the chip 15 is bonded. The chip 15 is bonded by a conductive bonding agent 16 and further the chip 15 is covered with resin 19. Ding like this, ionic impurities to be entered from the base plate is checked by the top coat 30 so that deterioration in the element 15 is preventable.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fluorescent display tube, commonly known as 1chip on GlassJ, in which a display panel and a driving circuit are integrated.
(hereinafter referred to as eOG) structure.

As a fluorescent display tube having a conventional COG structure, a structure as shown in FIGS. 1 and 2 shows a cutaway plan view of the main part and a cutaway sectional view of section 8-1-◆-A. . That is, to explain this conventional example, in the figure, 1 is an anode substrate that also serves as a drive circuit forming board, and a plurality of distribution coatings 2 and insulating coatings 3 are laminated and deposited on a substrate IA made of glass. , a segment electrode 4, a phosphor layer 5, etc., and a plurality of segments having the phosphor layer 5 constitute an anode display section 6 for displaying patterns such as numbers by the tff14, and this anode Display section 6
By arranging multiple digits in parallel, it is possible to selectively display multiple digit numbers, etc.

The wiring film 2 electrically connects adjacent common segment electrodes 4 through connection holes 7 provided in the insulating film 3,
Furthermore, the wiring is extended to the top of the board IB as an external drive circuit connection electrode. Further, a mesh-like control electrode 11 and a cathode 12 are arranged opposite to each of the anode indicators 'm6, and are extended by the wiring film 2 to the top of the substrate IB.

On top of one anode substrate having the anode display section 6, control @electrode 11, @electrode 12, etc., at least the upper window section 2- is provided with a top plate 13 made of transparent glass or the like, and the peripheral edge thereof The envelope is then hermetically sealed with a sealing material 22 such as low melting point frit glass to form an envelope.

Next, the drive circuit section 14 formed on the substrate IB will be explained. Regarding this conventional example, e
A MO8LSI 15 f 1 chip is mounted on the substrate In. The 0MO8LSI chip 15 is die-bonded onto the glass substrate In using a conductive or insulating adhesive 16. Next, the electrodes and wiring coating 2 on the chip 15
Wire bonding is performed to connect the pad portions 17 formed by the above steps. This is connected using gold l1i18'e, for example, by the thermosonic method. Furthermore, silicon or epoxy resin is coated as a protective film 19 over these to complete the drive circuit s14.

Such die bonding and wire bonding work is performed after the exhaust work process in the fluorescent display tube manufacturing process, and this is because the adhesive 1 used for die bonding ink is
It is determined from the heat resistance properties of 6. Furthermore, since the work is carried out after the evacuation step, it is important to perform bonding at as low a temperature as possible from the viewpoint of reducing the amount of gas released inside the fluorescent display tube.

In the conventional structure manufactured in this way, the external terminal 20
By attaching a crystal oscillator (not shown) to the unit and connecting it to a 12V DC power supply, a statically driven clock display can be performed. However, in conventional fluorescent display tubes having such a COG structure, malfunctions of the drive circuit section 14 often occur when used for a long time. This was due to the deterioration of the characteristics of the LS) l5 which was di-bonded.

As a result of investigating the cause of the deterioration of the LSI 15, it was found that it was due to the influence of ionic impurities from the glass substrate IB to which the LSI 15 was die-bonded. As is well known, although a pansivation layer of 5ins is formed on semiconductor devices, it cannot be considered as a complete protective film, and if sodium ions, chloride ions, water, etc. are adsorbed, they will be affected by it and will have a corrosive effect. This can lead to changes in device characteristics.

In a conventional fluorescent display tube having a COG structure, the LSI chip 15 is die-bonded directly onto the glass substrate In made of soda glass, so that sodium, potassium, etc. contained in the soda glass at about 20 wt% are removed. Impurity ions increase their mobility, especially when used under high temperature and high humidity conditions.1. This is thought to have had an adverse effect on surface wave diffusion.

Therefore, protecting the LSI chip from a large amount of ionic impurities contained in the glass substrate is a necessary condition for increasing the reliability of a fluorescent display tube having a COG structure.

The present invention solves the conventional problems as described above.
It is an object of the present invention to provide a fluorescent display tube having a G structure.

The main idea behind this is to protect the LSI from ionic impurities by providing a thin layer on the substrate to which LSII die bonding is performed to suppress ionic impurities, thereby obtaining a long-life COG structure fluorescent display tube. There is a particular thing.

The present invention will be explained in detail below using examples.

FIG. 3 is a cross-sectional view according to an embodiment of the present invention.

In the figures, the same members as in FIGS. 1 and 2 are denoted by the same reference numerals, and their basic roles are the same as in the conventional method. In particular, the display section on the glass substrate IA is the same as the conventional method, and the explanation will be omitted.
The drive circuit [14 formed on B will be explained.

In this example, several dozen fluorescent display tubes before LSI die bonding were placed in a quadrupole high frequency sputtering device, and Al5Os (i7 sputtering) was performed only on the designated glass substrate surface through a mask under the following conditions. Protective film 3 (l
formed.

Pressure and atmosphere; Argon I X 10-'T
orr applied voltage (1); anode 50V (2);
Auxiliary electrode 300■ (3); Target 100OV, 1 part export 7 high MJ
Power: 800vv-1000W6- Sputtering time: 6 minutes Sputtering film thickness: Approximately 30ooA Preheating of glass substrate: 100°0 Target (covering material): 99.8% Polycrystalline alumina This protective film 30 is used for die bonding of the LSI chip 15. The glass substrate is located at the same location as the glass substrate.

An LSi 15 was die-bonded using a conductive adhesive 16 onto the glass substrate manufactured as described above. Subsequently, the A/electrode on the chip 15 and the pad portion 17 formed by the wiring film 2 are connected by wire bonding. Here, the connection is made by the thermosonic method using gold wire 18. Furthermore, a silicone or epoxy resin 19 is coated over these to complete the drive circuit section 14.

In the fluorescent display tube of the present invention manufactured in this manner, the ionic impurities such as Na'' and Ni+ that diffuse into the glass substrate are blocked by the A4mOs protective film 30, and the L
The effect of preventing characteristic deterioration of SI elements was confirmed. Furthermore, when fil i Q is used as the protective film 30, A
/ * The same effect as Om was observed.

In other words, this application includes all cases in which a substance that prevents ionic impurities from a glass substrate is removed from a substrate portion on which an LSI chip is die-bonded, and the type of coating material that serves as a protective film and the method of removal are included. It is clear that it does not depend on The thickness of the protective film 30 also has the flexibility to be appropriately selected and used depending on the usage conditions of the fluorescent display tube.

Furthermore, although this embodiment describes only the case where one LSI chip is mounted on a segment-type fluorescent display tube, it is clear that this method is also effective when mounting multiple chips on a dot-type fluorescent display tube. It is.

[Brief explanation of drawings]

Figures 1 and 2 are a cutaway plan view of essential parts showing an example of a multi-digit fluorescent display tube with a conventional COG structure;
FIG. 3 is a cross-sectional view showing an embodiment of a multi-digit fluorescent display tube having a COG structure according to the present invention. 1...Glass substrate, 2...Wiring coating,
3... Insulating coating, 4... Segment electrode, 5... Phosphor layer, 6... Anode display section, 11... Control electrode, 12...Cathode, 13...Top plate, 14...Drive circuit section, 15...LSI chip, 17...
・Pad part, 19...Resin film, 20...
External terminal, 30...Protective film. 9- vJi second sentence? times

Claims (1)

[Claims] A multi-digit display section having a phosphor layer and a drive circuit section for operating the display section are separated into a fluorescent display tube having a structure in which they are integrally formed on the same substrate. A fluorescent display tube characterized in that a coating is applied to protect semiconductor devices from ionic impurities.