JP2626015B2 - Semiconductor device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to, for example, a liquid crystal display device in which a semiconductor chip for driving is directly and easily and reliably mounted on a liquid crystal panel formed of a transparent conductive film. The present invention relates to a semiconductor device.

2. Description of the Related Art In recent years, a thin and light-weight liquid crystal display device in which a driving semiconductor chip is directly mounted on a liquid crystal panel having a structure in which a liquid crystal material is filled in a gap between two glass plates having a transparent conductive film formed thereon. Has been actively conducted. As a typical method, a protruding connection metal electrode formed in advance by gold plating or the like on a semiconductor chip electrode portion and a connection electrode having a transparent conductive film formed on a glass plate are opposed to each other. State (semiconductor chip faces down)
In this case, there is a method of performing electrical connection and bonding / fixing with a conductive adhesive interposed therebetween. At this time, the conductive adhesive is previously formed on the protruding connection metal electrode surface of the semiconductor chip by a transfer method, a dipping method, or the like, and is placed in alignment with the transparent conductive film pattern on the glass plate. After that, it is electrically connected by thermosetting.

FIG. 5 shows a connection structure in the case where a conductive adhesive is used in this liquid crystal display device. Reference numerals 1a and 1b denote two glass plates constituting a liquid crystal panel, which are transparent conductive films 4a and 4b, respectively.
On the glass plate 1a, the transparent conductive film 4a extends to the outside and is formed as a connecting electrode 4a in the shape of an eave as shown in the figure. The semiconductor chip 7 on which the metal electrode 6 is formed is electrically connected in a face-down state, and is adhered and fixed. Reference numeral 2 denotes a liquid crystal, and reference numeral 3 denotes a sealant.

Problems to be Solved by the Invention In the above-mentioned bonding structure, as shown in FIG. 4, a transparent conductive film generally formed on the surface of an eave-shaped glass plate 1a
In order to perform electrical connection and bonding / fixing via the conductive adhesive 5 in a state in which the protruding connection metal electrode 6 of the semiconductor chip 7 is face-down directly on the connection electrode 4a made of 4a, Most of the connection electrode 4a 'is exposed (including a portion where the semiconductor chip 7 is not mounted). Transparent conductive films generally used for transparent electrodes are oxides and are stable in dry air because they are oxides.However, they are easily decomposed in the presence of moisture, and when a voltage is applied, electrolytic corrosion or short-circuit between adjacent electrodes causes excessive current. When applied to a liquid crystal display device, such as disconnection of the transparent conductive film, or adhesion of conductive dust such as metal scraps or ionic contaminants such as sweat or saliva, which may cause short-circuit or corrosion In addition, there were major problems that lacked quality and long-term connection reliability. As one of the measures, the connection electrode 4
a ', that is, a structure in which nickel plating is applied to the transparent conductive film by electroless plating or the like, and a metal film is applied by further gold plating. In this case, if there is slight contamination on the surface of the transparent conductive film, the surface of the transparent conductive film is not uniformly and completely covered with the plating film, and there is a problem that many pinholes are generated. Furthermore, since the thickness of the transparent conductive film is usually 300 to 2000 mm and extremely thin, there is a problem that the plating film is formed in an extremely poor state in the thickness direction, that is, on the side surface of the transparent conductive film. As described above, permanent measures such as the intrusion of moisture from the pinholes of the plating film or the interface between the transparent conductive film and the plating film due to the presence of moisture and the occurrence of electrolytic corrosion by applying a voltage are provided. Not.

The present invention solves such a problem, and completely protects a transparent conductive film in a liquid crystal display device or the like in which a semiconductor chip is directly mounted on a liquid crystal panel in a face-down state using an anisotropic conductive adhesive. And a semiconductor device which can be applied to a high quality and high reliability liquid crystal display device.

Means for Solving the Problems To solve the above problems, a semiconductor device of the present invention
On an insulating substrate, a semiconductor chip provided with a protective film made of a synthetic resin on a connection electrode whose upper layer is a metal film and a lower layer is a transparent conductive film, and provided with a protruding connection metal electrode, The connection electrode provided on the insulating substrate is disposed so as to face each other, and the connection metal electrode of the semiconductor chip is pierced through the protective film by thermocompression bonding via an anisotropic conductive adhesive. It is configured to be mounted so as to be electrically connected to the connection electrode.

According to this configuration, a protective film made of a synthetic resin is further formed on a connection electrode having an upper layer made of a metal film and a lower layer made of a transparent conductive film on the insulating substrate, and In the electrical connection between the semiconductor chip provided with the connection metal electrode having a shape and the connection electrode provided on the insulating substrate, the protective film is melted at the time of thermocompression of the semiconductor chip and provided on the semiconductor chip by a pressing force. The electrical connection can be obtained by being pierced by the protruding connection-shaped metal electrode and being largely removed at the peripheral portion other than the connection metal electrode. Moreover, by providing a metal film on the upper layer on the insulating substrate as described above, the transparent conductive film of the lower layer is roughly protected in advance, and the metal electrodes for connection in the semiconductor chip are electrically connected. Since the protective film remains on the connection electrode in the portion that is not covered and the portion other than the semiconductor chip (exposed portion where the semiconductor chip is not mounted), the protection film is doubly protected. And the like, and as a result, a state in which the connection electrode is completely protected from the outside air can be maintained, and a semiconductor device with high quality and high reliability can be obtained.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In FIG. 2a, reference numerals 11a and 11b denote glass plates as two insulating substrates constituting a liquid crystal panel, on which transparent conductive films 14a, 14a 'and 14b are formed, respectively. The film 14a 'extends to the outside and is exposed like an eave. In addition, 12 is a liquid crystal and 13 is a sealant. Reference numeral 15 denotes a metal film provided on the transparent conductive film 14a ',
a ′ and the metal film 15 constitute a connection electrode. Reference numeral 16 denotes a protective film made of a synthetic resin provided on the metal film 15, and a metal film 1 on the transparent conductive film 14a '.
5 and a double protective film of a synthetic resin 16 are provided. In the present embodiment, as the metal film 15, a nickel plating film having a thickness of 0.8 μm was formed by an electroless plating method, and then a gold plating film having a thickness of 0.05 μm was formed by an electroless plating method. , And others, gold, silver,
Single-layer coatings of copper, chromium, platinum, palladium, aluminum, solder, etc., as well as metals formed by electroless plating, electrolytic plating, sputtering, vapor deposition, etc. of these multilayers, alloys, etc. Coatings are also effective. Further, in the present embodiment, as the protective film 16 made of a synthetic resin, in the connection by thermocompression bonding of the semiconductor chip, a thermoplastic polyester resin which easily melts and has a high adhesive strength is used, and the protective film 16 is formed on the transparent conductive film 14a '. In order to completely cover the formed metal film 15, the entire surface was coated to form a protective film. In addition, acrylic,
Thermoplastic resins such as polyvinyl butyral and polystyrene, thermoplastic rubbers such as styrene-butadiene copolymer rubber, uncured liquid phenolic resin, epoxy resin, epoxy-modified phenolic resin, curable resin such as silicone resin, uncured liquid Of epoxy acrylate oligomers, acrylate monomers, and other photo-curable resins, or a mixture thereof is also effective. FIG. 2B is a cross-sectional view taken along the line AA ′ in FIG.
A connection electrode composed of a transparent conductive film 14a ′ formed on 11a and a metal film 15 formed thereon,
Also, a state is shown in which a protective film 16 is formed on the entire surface including a blank portion other than the connection electrodes.

Next, as shown in FIG. 3, the electrode portions of the semiconductor chip 18 are previously formed with gold-plated connecting metal electrodes for projection.
17 is a semiconductor chip including the connection metal electrode 17
An anisotropic conductive adhesive layer 21 formed by dispersing conductive powder 20 in synthetic resin 19 was formed on the surface of 18. If this structure is described in detail, gold is used in the present embodiment as the protruding connection metal electrode 17 on the semiconductor chip 18, but
Alternatively, a simple substance or a composite substance of solder, silver, copper, platinum, palladium, nickel, chromium, etc. may be used.

Further, as the synthetic resin 19 constituting the anisotropic conductive adhesive 21, the same as the protective film 16 is preferable, and in this embodiment, a thermoplastic polyester resin was used. Further, as the conductive powder 20, in the present embodiment, a polystyrene resin ball having a particle diameter of 1 to 40 μm, an electroless nickel plating film was used, and then an electroless gold plating film was further used. Nickel, solder,
Metal powders such as gold, silver, and copper, and conductive powders such as carbon powder and graphite powder can also be used.

In this embodiment, in order to obtain the anisotropic conductive adhesive 21, 100 parts by weight of the thermoplastic polyester resin is added to the conductive powder 24 in the form of a styrene resin ball having a plating film as described above.
Parts by weight were added and mixed by a ball mill to obtain an anisotropic conductive adhesive. The anisotropic conductive adhesive 21 was formed into a sheet and temporarily fixed at a low temperature of about 80 ° C. to the surface of the semiconductor chip 18 including the connecting metal electrodes as shown in FIG. 3 by thermocompression bonding. Furthermore, in the present embodiment, the anisotropic conductive adhesive 21 is formed on the surface of the semiconductor chip 18 as described above, but is not limited thereto.
As shown in FIG. 4, on the glass plate 11a (the transparent conductive film 14)
a ', including the metal film 15 and the protective film 16), the anisotropic conductive adhesive (sheet) 21 formed in advance does not hinder the present invention.

Next, as shown in FIG. 1, the connection metal electrode 17 and the glass plate 11a on the semiconductor chip 18 on which the protruding connection metal electrode 17 made of gold and the anisotropic conductive adhesive 21 are formed in advance. (The semiconductor chip 18 is in a face-down state) with the connection electrodes formed on the other side facing each other.
The semiconductor chip 18 was pressed from the back surface of the semiconductor chip 18 with a 140 ° C. heating tool at a pressure of 3 kg / cm ² for 30 seconds, and was electrically connected and fixed to obtain a liquid crystal display device. According to such a connection structure, as shown in FIG.
During the thermocompression bonding, the metal is melted and pierced by the protruding connection metal electrode 17 formed on the semiconductor chip 18 by the pressurizing force, and at the same time, flows to the peripheral portion other than the connection metal electrode 17, and is mostly removed, and at the same time, , Conductive powder in anisotropic conductive adhesive 21
Reference numeral 20 denotes a metal electrode 17 for connection of a semiconductor chip 18 and a glass plate 11
It is sandwiched between the connection electrodes on a and electrical connection is obtained. In addition, since the protective film 16 and the synthetic resin 19 constituting the anisotropic conductive adhesive 21 are bonded over the entire surface of the semiconductor chip 18 except for the connecting metal electrode 17 by thermocompression bonding, the bonding strength is increased. Can be significantly improved. Furthermore, the protective film 16 remains in a portion of the connection electrode where the semiconductor chip 18 is not mounted, and is shielded from the outside air, so that a moisture-proof effect can be obtained. Incidentally, in order to confirm the moisture-proof effect of the liquid crystal display device obtained according to the present embodiment, the liquid crystal display device 10 was used.
Side, while applying the applied voltage DC15V each, 6
The sample was put in a constant temperature and humidity atmosphere of 90 to 95% RH at 0 ° C. to perform an electric corrosion resistance test. The results obtained are shown in the following table.

Further, as Comparative Examples 1 and 2, liquid crystal display devices were manufactured by a conventional technique.

COMPARATIVE EXAMPLE 1 As shown in FIG. 5, transparent conductive films 4a and 4b are formed on two glass plates 1a and 1b, respectively. As a result, a liquid crystal panel exposed like an eave was manufactured. Silver powder is dispersed in an epoxy resin on the transparent conductive film 4a formed on the eaves-like portion of the liquid crystal panel, on the connecting metal electrode 6 having a protruding shape formed by gold plating on the electrode portion of the semiconductor chip 7 in advance. The conductive adhesive obtained by the dip method was opposed to each other, aligned, mounted, and then thermoset at 150 ° C., electrically connected and fixed to obtain a liquid crystal display device.

Comparative Example 2 As Comparative Example 2, on the connection electrode 4a made of the transparent conductive film 4a exposed in an eaves shape of the liquid crystal panel in Comparative Example 1,
After forming a nickel plating film having a thickness of 0.8 μm in the same manner as in this example, a gold plating film having a thickness of 0.05 μm was further formed,
A semiconductor chip was electrically connected and fixed in the same manner as in Comparative Example 1 to obtain a liquid crystal display device.

In Comparative Examples 1 and 2, similarly to the present example, an electrolytic corrosion resistance test was performed on each of ten liquid crystal display devices. The results obtained are shown in the following table.

As shown in the above table, in the liquid crystal display device of the present example, in the electric corrosion resistance test, no electric corrosion breakage failure occurred at all.

Effect of the Invention The semiconductor device configured as in the present invention has a semiconductor chip having a double protective film configuration in which a protective film made of a metal film and a synthetic resin is formed on a transparent conductive film provided on an insulating substrate. The moisture resistance and dust resistance of the transparent conductive film in the part where it is not mounted can be remarkably improved, and when the semiconductor chip is electrically connected and fixed in a face-down manner, the electrical connection is made by a protruding connection metal electrode, Through the anisotropic conductive adhesive, the protective film made of a synthetic resin is pierced, and an ohmic connection can be obtained to the metal film provided on the transparent conductive film by the multiple conductive powders in the anisotropic conductive adhesive. In this state, the entire surface of the semiconductor chip other than the connection metal electrodes is adhered and fixed by the protective film made of synthetic resin, so that the connection reliability can be significantly improved. Furthermore, in order to prevent crosstalk in a liquid crystal display device, an attempt to provide a metal film on a transparent conductive film for the purpose of reducing the resistance value has been conventionally performed.
Although the electrolytic corrosion disconnection could not be completely prevented, it can be achieved by the configuration of the present invention. As a result, a highly reliable and high-quality liquid crystal display device of a semiconductor chip mounting type is obtained. It becomes.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a semiconductor device according to one embodiment of the present invention, FIGS. 2a and 2b are partial cross-sectional views illustrating the configuration of one embodiment of the present invention, and FIG. Partial cross-sectional view showing a state in which an anisotropic conductive adhesive is provided on the surface of a semiconductor chip provided with a protruding connection metal electrode used in an embodiment of the present invention,
FIG. 4 is a sectional view of a main part showing another embodiment of the present invention, and FIG. 5 is a partial sectional view showing a connection state of a conventional semiconductor device. 11a, 11b: insulating substrate, 12: liquid crystal, 13: sealant, 14a, 14a ', 14b ... transparent conductive film, 15: metal film, 1
6 ... Protective film, 17 ... Metal electrode for connection, 18 ... Semiconductor chip, 19 ... Synthetic resin, 20 ... Conductive powder, 21 ... Anisotropic conductive adhesive.

Claims (1)

(57) [Claims] A protective film made of a synthetic resin is provided on a connection electrode having an upper layer made of a metal film and a lower layer made of a transparent conductive film, and a projection-shaped connection metal electrode is provided on an insulating substrate. The semiconductor chip is disposed so as to face the connection electrode provided on the insulating substrate, and the connection metal electrode of the semiconductor chip is protected by the thermocompression bonding via an anisotropic conductive adhesive. A semiconductor device mounted so as to penetrate a film and be electrically connected to the connection electrode.