JPH06302645A - Terminal connection method of electronic components, electronic equipment connected according to the connection method and terminal connection bump therefor - Google Patents

Abstract

PURPOSE:To make it possible to interconnect terminal electrodes even in an area where the amount of gaps between opposed electrodes exceeds a specified value by repeating several times a process which forms metal wire bumps and connecting both terminal electrodes by way of a conductive bonding agent. CONSTITUTION:A bump 13-1 is formed by means of wire bonding at a specified position on a terminal electrode 2 formed on one electronic component. Then, a bump 13-2 is formed on the bump 13-1 further by means of wire bonding. A conductive bonding agent is deposited on a terminal electrode formed at the top of a bump 13-4 in the uppermost stage or in the other component in this manner. The terminal electrode 2 formed on one electronic component 3 by way of the conductive boding agent is connected to the terminal electrode formed on the other electronic component. In this manner, the terminals formed on a plurality of electronic components are interconnected. It is, therefore, possible to interconnect terminal electrodes in a wide area where the amount of gaps ranges from some mum to 100mum and over.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of connecting terminals of electronic parts, an electronic device having a plurality of substrates integrated by this connecting method, or a document reading apparatus having a light receiving element and a light emitting element, and a terminal connection thereof. For laminated metal wire bumps for automobiles.

[0002]

2. Description of the Related Art Conventionally, when connecting an electronic component to a wiring pattern on a substrate, the terminals of the electronic component and the terminals provided on the substrate are connected to each other in the direction of facing terminal electrodes. A method of connecting through a conductive film or conductive particles,
Alternatively, a method is known in which a bump is formed on a terminal by soldering or bonding and both are connected via the bump. The method of connecting using an anisotropic conductive film or conductive particles, while the process is simple, not only difficult to form terminals of fine pitch, there is a problem such as low heat resistance, Further, the soldering method has high reliability, but has a drawback that the terminal electrode needs to be subjected to metallizing treatment, which complicates the process. On the other hand, for example, the Technical Report of the Institute of Electronics, Information and Communication Engineers (CPM8
9-45, pp7-12) The method of using metal bumps formed by bonding as disclosed in "COG mounting method by stat bump method" can be applied to fine pitch terminals and does not require metallization. Have the advantage of.

FIG. 4 shows the shape and manufacturing process of a conventional metal bump. In FIG. 4 (a), one end of the metal wire 1 is formed on a spherical end 11 by electric discharge or the like, As shown in b), this is pressed onto the terminal electrode 2 formed on the substrate 3 to be connected by thermocompression bonding with ultrasonic wave, and the connection portion 12 is formed. After that, as shown in FIG. 3C, the bent portion 14 is formed on the metal wire 1 and the other end 1 is formed.
5 is cut to form metal bumps. That is, one end 12 of this metal wire bump is connected to the terminal electrode 2, but the other end 15 is a free end.

The connection using the metal wire bump according to the above-mentioned conventional technique is effective when the gap between the terminal electrode of the electronic component to be connected such as a liquid crystal display element and the terminal electrode on the substrate is about several tens of μm. However, when connecting an electronic component having a gap of 50 μm or more, it is difficult to use because the height of the metal bump is insufficient. As a similar method, there is a method described in JP-A-1-227458. In this method, only the first bonding is performed using a metal wire, and the wire is cut by laser light without forming the second bonding to form a convex bump. However, this method cannot be applied to a document reading apparatus in which the gap between the opposing electrodes is large, to which the present invention is applied, because the height of bumps that can be formed is at most 50 μm.

On the other hand, an image input / output device is widely used in information related equipment, and a cathode ray tube (CRT) and a liquid crystal display device (L) are used as a display which is one of the image output devices.
There are various methods such as CD), electroluminescence device (ELD), and plasma display device (PDP). With the development of high-density packaging technology, drive ICs have come to be directly mounted on a display substrate, and recently, a device having a compact display such as a portable personal computer or an electronic notebook has been developed. As the image sensor, which is one of the image input devices, a contact type line image sensor having a size of a document width using a photoelectric conversion film such as amorphous silicon is mainly used. An image sensor of this type is disclosed in JP-A-53-53.
As disclosed in Japanese Patent No. 119619, a two-dimensional image sensor that does not require a drive system such as paper feeding has been proposed. However, in the image sensor having such a configuration, an illumination device that can move a light source for scanning is provided. There is a drawback in that it is difficult to reduce the size because it is required and the size of the original is limited.

Further, Japanese Patent Laid-Open No. 1-106467 discloses a technique in which these display element and image reading element are formed in distant portions on the same substrate, and the image is read immediately after the image is read. There is. But,
The technique disclosed in this publication has a drawback that a display device and an image reading device are formed in different regions, so that when a lighting device such as a light source is added, the device becomes considerably large.

[0007]

The present invention has been invented in view of such a situation, and a first object of the present invention is to provide a gap between opposing terminal electrodes of several μm to 10 μm.
An object of the present invention is to provide a terminal connection method for electronic components that enables connection between terminal electrodes even in a wide range of 0 μm or more. A second object of the present invention is to make a two-dimensional light emitting element and a light receiving element on separate substrates, and fix the two substrates integrally with each other with a desired gap so that the respective elements face each other. An object of the present invention is to provide an electronic apparatus such as a document reading device that connects the drive electrode of the light emitting element to the light receiving element substrate side with high reliability. A third object of the present invention is to provide a laminated metal wire bump for the above connection.

[0008]

In order to achieve the first object of the present invention, a step of forming a first metal wire bump on one terminal electrode by wire bonding and a second metal wire bump thereon. Forming step, repeating this step a plurality of times, attaching a conductive adhesive to the top of the uppermost metal wire bump or the other terminal electrode, and connecting both terminals via this conductive adhesive. It consists of an electronic component connecting step of connecting electrodes. Further, in order to achieve the second object of the above invention, a document reading in which a light receiving element substrate having a light receiving element and a terminal electrode on the inner surface and a light emitting element substrate having a light emitting element and a terminal electrode on the inner surface are integrally arranged facing each other The device has bump electrodes of a laminated structure formed on one of the light receiving element substrate and the light emitting element substrate and formed on a terminal electrode, and a terminal electrode on the other one of the light receiving element substrate and the light emitting element substrate. And the other terminal electrode is connected to the laminated structure bump electrode by a conductive adhesive adhered to the top of the laminated structure bump electrode formed on the one terminal electrode or the other terminal electrode, and the light receiving element substrate A transparent spacer for forming a gap is provided between the substrate and the light emitting element substrate. In order to achieve the third object of the present invention, a wire ball formed by electric discharge is thermocompression-bonded to a terminal electrode, and a capillary tool is pulled up while the wire is clamped to cut the wire. A laminated metal wire bump is formed by stacking a number of bumps.

[0009]

According to the present invention, by using the laminated metal wire bumps, it is possible to increase the contact area with the electrodes while maintaining a high mounting density, and thus it is possible to improve the connection reliability. Since the gap between the substrates is maintained by the transparent spacer, it is possible to realize the configuration of the document reading device with a small gap variation.

[0010]

EXAMPLES The present invention will be specifically described below based on examples. FIG. 1 is a schematic diagram illustrating a process of forming a metal wire bump. As shown in FIG. 1A, first, the tip of a metal wire 1 having good conductivity such as gold is heated and melted by electric discharge or the like to form a molten spherical portion 11. Next, as shown in FIG. 1B, the fused spherical portion 11 is connected to the terminal electrode 2 provided on the surface of the substrate 1 by thermocompression bonding or the like using ultrasonic waves to form a ball 12. Thereafter, as shown in FIG. 3C, after pulling up a capillary tool (not shown) while the metal wire 1 is clamped, the metal wire 1 is cut by, for example, a laser beam to form a convex bump 13-1. . Next, as shown in FIG.
The tip of the metal wire 1 is heated and melted by the same heating method to form the molten spherical portion 11-2 again. This spherical part 1
As shown in (e) of the same figure, 1-2 is pressed against the upper portion of the bump 13-1 formed in the previous step and connected by thermocompression bonding or the like combined with ultrasonic waves to connect the ball 12-on the bump 13-1.
Form 2. After that, as shown in FIG. 3F, after pulling up a capillary tool (not shown) while the metal wire 1 is clamped, the metal wire 1 is cut by the same cutting method and placed on the bump 13-1. A second-layer convex bump 13-2 is formed. FIG. 1G shows a case where four layers of bumps are stacked by repeating the same forming method twice, and the bumps 13-3 of the third stage and the bumps 13-4 of the fourth stage are stacked and laminated. Bumps 13 are formed.

In this embodiment, the wire diameter 1 is 25-28.
Assuming that the thickness of the ball 12 is μm, the ball 12 has a thickness m of about 20 μm and a diameter n of 80 to 85 μm. A height H of about 100 μm is obtained in the laminated bump 13 in which four layers are stacked.

FIG. 2 is a diagram illustrating a step of attaching a conductive adhesive to the tops of the laminated bumps formed by the manufacturing method of FIG. The laminated metal wire bump 13 obtained by the above method is formed on the upper surface of the terminal electrode 2 provided on the surface of the substrate 3, and the adhesive attaching jig 4 having the conductive adhesive 5 applied on the bottom surface thereof is formed as shown by an arrow. By vertically moving from the upper side to the lower side, the adhesive is uniformly attached to the top of the laminated metal wire bump 13. As the conductive adhesive, an epoxy resin added with Ag or Pd fine powder is suitable, but not limited to this as long as it is a material having good conductivity and adhesiveness.

FIG. 3 shows an integrated device according to the second invention in which a light emitting device and a light receiving device are connected to each other by using a laminated metal wire bump formed by the method shown in FIGS. It is sectional drawing which shows the schematic structure of the Example which carried out, and the partial enlarged view which shows the structure of a bump part is attached as FIG. The document reading device of this embodiment is configured by integrating a light receiving device 20 and a light emitting device 30 so as to face each other with a transparent spacer 40 for forming a gap therebetween.

In the light receiving device 20, a plurality of light receiving elements 22 are arranged on a light receiving element substrate 21, and the substrate 21
A light-receiving element terminal electrode 23 connected to each light-receiving element is provided at one end portion of the lead electrode 2.
4 are connected and configured. Further, a light emitting element terminal electrode 25 is provided at the other end of the substrate 21, a lead electrode 26 is connected to the terminal electrode, and a conductive adhesive 16 is provided on the top of the surface of the terminal electrode. The applied laminated metal wire bumps 13 are provided. The light emitting device 30 is configured by providing a plurality of light emitting elements 32 on a transparent light emitting element substrate 31 such as glass. The surface of the light emitting element is covered with a light shielding layer 33, and an entrance window 34 is provided in the light shielding layer at a position facing the light receiving element 22 provided in the light receiving device 20. A light emitting element terminal electrode 35 connected to each light emitting element 22 is provided at an end of the glass substrate 31, and a conductive material provided on the top of the bump 13 provided on the light emitting element terminal electrode 25 on the light receiving device 20 side. The terminal electrode of the light emitting element is connected to the conductive adhesive 16 and is taken out through the laminated metal wire bump 13.

The light receiving element substrate 21 and the light emitting element substrate 31 are opposed to each other so that the light receiving element 22 and the light emitting element 32 are inside, and the positions of the light receiving element 22 and the light emitting element 32 are arranged to correspond to each other. Let The light emitting element substrate 31 is made of a transparent material such as glass, and the original 6 is placed on the surface of the light emitting device 30, that is, the surface opposite to the light emitting element 32. The light from the light emitting element 32 is irregularly reflected by the original 6, and the reflected light is applied to the light receiving element 22 through the entrance window 34. Further, the light shielding layer 33 is formed so that the light from the light emitting element 32 is not directly irradiated to the light receiving element 22.

In the document reading apparatus having such a structure,
In terms of reading resolution, it is desirable that the distance between the light emitting element and the document and the distance between the light emitting element and the light receiving element are the same, and it is desirable that the value is smaller. In the case of the configuration of this embodiment, the above value is determined by the thickness of the light emitting element substrate. That is, since the minimum thickness of the light emitting element substrate is 50 to 100 μm due to a problem in handling in the manufacturing process, the distance between the light emitting element and the light receiving element, that is, the height required by the metal wire bump can be formed up to about 100 μm. Will be needed. When the metal wire bump of the present invention is used, a bump having a height of about 100 μm can be formed by stacking about four layers.
Suitable for bumps of this document reading device. Furthermore, the amount of gap in the substrate can be kept uniform over the front face of the device by inserting transparent, uniform diameter spherical spacers. The diameter of the metal wire bump is 80-85
Since it is μm, a wide gap amount of 100 μm can be realized while maintaining a high mounting density of 8 line / mm (125 μm pitch).

In the above embodiment, the conductive adhesive is applied to the top of the laminated metal wire bump, but
Of course, a conductive adhesive can be applied to the terminal electrode side by screen printing or the like for connection. In the embodiment of FIG. 3, the light emitting element 32 has a thickness of 1
EL (el) using ZnS: Mn as the material of the light emitting layer on the surface of the light emitting element substrate 31 substrate made of glass of 00 μm
An electroluminescence element was formed and used. A photodiode formed of amorphous Si is used as the light receiving element 22. Amorphous Si is suitable for such a large area device because a uniform film can be easily deposited on a large area by the plasma CVD method or the like. As the light emitting device, various other light emitting devices can naturally be used instead of the above EL.

In the document reading apparatus of this embodiment, the two-dimensional light emitting element not only functions as a light source for illuminating a document, but also functions as a display device by including a driving device. Can be made.

In the above embodiment, the document reading device in which the light emitting device and the light receiving device are integrated is shown. However, the present invention is not limited to this example. For example, a liquid crystal display device in which an LCD substrate and a light emitting device substrate are integrated. As a matter of course, the present invention can be applied to a display device in which a display unit and a light emitting unit or a drive unit formed on separate substrates are integrated, and naturally applied to other integrated electronic devices. can do.

[0020]

As described above, by stacking metal wire bumps, a height of up to about 100 μm can be freely realized, and an epoxy-based conductive paste is uniformly attached to the bump vertices, After aligning with the electrodes on the light emitting element substrate, the light emitting element substrate is uniformly pressed and baked at 150 ° C. for about 10 minutes,
Electrode 25 on light receiving element substrate and electrode 35 on light emitting element substrate
Can be connected via the laminated metal wire bumps 13. Furthermore, according to the present invention, even in the case of a display element such as an EL light emitting element in which several mA flows per element at a high driving voltage, the contact area of the electrodes can be increased without lowering the mounting density, and highly reliable connection is possible. Becomes In addition, the particles for forming the gap can be configured to have a small gap variation similar to that of a liquid crystal cell. As described above, the upper and lower electrodes can be contacted with high reliability without lowering the mounting density.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a shape of a metal wire bump according to the present invention and a step of forming the bump.

FIG. 2 is an explanatory diagram illustrating an adhesive attaching step according to the present invention.

FIG. 3 is a sectional view showing the structure of a document reading apparatus according to the present invention.

FIG. 4 is a schematic view showing a shape of a metal wire bump and a forming process thereof according to a conventional technique.

[Explanation of symbols]

1 metal wire, 2 terminal electrode, 3 substrate, 4
Adhesive attachment jig, 5 conductive adhesive, 11 fused spherical portion, 12 ball, 13 bump, 16 conductive adhesive, 20 light receiving device, 21 light receiving device substrate,
22 light receiving element, 23 light receiving element terminal electrode, 2
4, 26 lead wires, 25 light emitting element terminal electrodes,
30 light emitting device, 31 light emitting device substrate, 32 light emitting element, 33 light shielding layer, 34 incident window, 35 light emitting device terminal electrode.

Claims (5)

[Claims] 1. A method of connecting terminals of an electronic component for connecting terminals formed on a plurality of electronic components, wherein bumps are formed by wire bonding at predetermined positions on a terminal electrode formed on one electronic component. A step of further forming a bump on the bump by wire bonding, a step of attaching a conductive adhesive to the terminal electrode formed on the top of the uppermost bump or the other component, and A method of connecting terminals of an electronic component, comprising a step of connecting electronic components between the terminal electrode formed on the one electronic component and the terminal electrode formed on the other electronic component via an adhesive. 2. The method for connecting terminals to an electronic component according to claim 1, further comprising the step of forming bumps at a predetermined stage by wire bonding on the formed laminated bumps. 3. An electronic device in which a first substrate having an electronic component and a terminal electrode on an inner surface thereof and a second substrate having an other electronic component and a terminal electrode on an inner surface thereof are integrally disposed so as to face each other, A bump electrode having a laminated structure in which a plurality of bumps are laminated on a terminal electrode formed on either the first substrate or the second substrate; and the first substrate or the second substrate A terminal electrode on the other of the two terminal electrodes, the other terminal electrode to the laminated structure bump electrode by a conductive adhesive adhered to the top of the bump electrode of the laminated structure formed on the one terminal electrode or the other terminal electrode An electronic device characterized by being connected. 4. A document reading apparatus in which a light-receiving element substrate having a light-receiving element and a terminal electrode on its inner surface and a light-emitting element substrate having a light-emitting element and a terminal electrode on its inner surface are integrally arranged facing each other, wherein the light-receiving element substrate or the A bump electrode having a laminated structure formed by laminating a plurality of bumps on a terminal electrode formed on one of the light emitting element substrates, and a terminal electrode on the other of the light receiving element substrate or the light emitting element substrate. , While connecting the other terminal electrode to the laminated structure bump electrode by a conductive adhesive attached to the top or the other terminal electrode of the laminated structure bump electrode formed on the one terminal electrode, and the light receiving element substrate An original reading apparatus, wherein a transparent spacer for forming a gap is provided between the light emitting element substrate and the light emitting element substrate. 5. A plurality of layers of convex bumps formed by thermocompression bonding a wire ball formed by electric discharge to a terminal electrode, pulling up a capillary tool with the wire clamped, and cutting the wire. A laminated metal wire bump characterized by: