JPH04340523A - Production of wiring substrate - Google Patents

Abstract

PURPOSE:To easily produce the wiring substrate by irradiating the part of defective parts with light energy with a laser oscillator from the rear side of a transparent base material, thereby selectively removing a high-polymer material and exchanging the parts when a defect is generated in the parts of the wiring substrate formed by coating the parts and thin-film wirings with the high-polymer material. CONSTITUTION:The light energy generated by the laser oscillator 6 is condensed by an optical system 7 and the part having the defective parts 3 is irradiated with this light energy from the rear surface of the transparent base material 1. The chemical bond between the transparent base material 1 and the high- polymer material 5 is cut by the irradiation with the light of the high energy in such a manner and, therefore, the high-polymer material 5 peels from the transparent base material 1. This high-polymer material can easily be removed if the material is selectively heated. A heating tool, such as soldering iron, and a lamp, hot air blower, and laser are applicable as the means for heating and other heating means are equally employed. After the defective parts 3 are removed, the parts 3 are freshly mounted and packaged, by which the wiring substrate is produced.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a substrate for a liquid crystal display device used in office automation equipment such as computers and word processors. More specifically, we selectively remove the polymer material of thin film wiring, components, and wiring boards made of polymer materials formed on transparent substrates, and use this polymer material to remove electrically defective materials that are covered or buried. This relates to a method for manufacturing wiring boards for which parts are replaced and repaired.

0002

2. Description of the Related Art In recent years, image display devices using liquid crystals are thinner and lighter than cathode ray tubes (Cathode Ray Tubes).
n) Used in many devices. In a liquid crystal display device (the schematic structure of which is shown in Figure 3), liquid crystal is sealed between two transparent glass substrates formed with a thin film, and a display signal, that is, a drive signal, is applied to the thin film wiring to drive the liquid crystal. do. In order to supply drive signals, a plurality of components such as LSIs are usually required. Conventionally, this driving L
After the SI was mounted on another base material 14 different from the glass base material 1, the transparent base material 1 and the other base material 14 were connected. This method requires an additional base material 14, which limits miniaturization of the liquid crystal display device. Recently, a method of directly mounting and mounting this driving LSI on a transparent base material, for example, the glass base material 1, without using another base material has been studied. In particular, the method of directly mounting and mounting unmolded LSI chips (COG: Chip On
Glass) is attracting attention as the method for achieving the most miniaturization. A promising method for electrical connection is a method (flip-chip method) in which the input/output terminals of the LSI chip and the thin film wiring are connected and mounted using fine solder protrusions. After mounting, the LSI chip is covered with a polymer material and buried in order to protect the LSI chip.

[0003] During the process after mounting an LSI chip or during actual use of a liquid crystal display device, the LSI may be electrically damaged or solder protruding electrodes may be damaged due to the effects of static electricity and thermal stress applied from outside. This may result in defects such as cracking or coming off. In this case, it is necessary to remove the defective LSI chip from the base material and replace or repair it with a normally operating LSI chip.

As a conventional method for removing a defective LSI chip and repairing a wiring board, a conventional method shown in FIG. 2 has been considered. In the figure, 1 is a transparent base material, for example, a glass base material, 2 is a wiring formed on the transparent base material,
For example, indium-tin composite oxide (ITO; In
Thin film wiring made of (dium thin oxide)
3 is a component electrically connected to the thin film wiring 2 and placed on the transparent base material 1, such as an LSI (Large Scale
Integrated Circuit) chip, 4
5 is a bonding member that electrically connects the thin film wiring 2 and the component 3, such as solder; 5 is a polymer material that covers or embeds the component 3, such as epoxy resin; 12 is a material that chemically dissolves and removes the epoxy resin; 13 is a box for filling the solvent 12, such as sodium hydroxide solution. In this method, a wiring board with a defective LSI chip 3 as a component is immersed in a solvent 12 to remove the polymeric material covering and embedding the component 3, and the LSI chip is replaced.

[0005]

[Problem to be Solved by the Invention] However, it is difficult to selectively immerse the polymer material of a defective chip in a solvent in order to remove only the polymer material of a defective chip from among a plurality of LSI chips mounted. be. Furthermore, solvents that have the effect of dissolving and removing polymeric materials generally have a negative effect, such as dissolving thin film wiring such as ITO, so it is impossible to partially replace parts using this conventional method. In reality, however, wiring boards and liquid crystal display devices with defective LSI chips mounted on them are currently being discarded.

[0006] The present invention has been made in order to solve such problems, and its purpose is to disclose a method for selectively removing polymeric materials covering and embedding parts mounted and mounted on a transparent base material. shall be. Furthermore, this method allows selective removal and replacement of this component without causing any damage to the wiring on the transparent substrate.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an electrical thin film wiring formed on one main surface of a transparent base material having at least two main surfaces, and an electrical connection between the thin film wiring and the thin film wiring. A method for producing a wiring board made of a polymeric material that connects and embeds or covers parts disposed on the transparent base material, the thin film wiring, and the parts, the method comprising: from the other main surface of the transparent base material; selectively photochemically or thermally altering the polymer material near the interface between the polymer material and the transparent substrate by irradiating the polymer material with light energy through the transparent base material; The method of manufacturing a wiring board is characterized in that the polymer material is selectively removed, and the parts are replaced and buried with the polymer material.

[0008]

[Operation] The transparent base material and the polymeric material are bonded by some kind of chemical bonding force. This is because a transparent substrate typified by a glass plate has a smooth surface, and there is almost no so-called anchor (wedge effect) between it and the polymer material. The energy of light is inversely proportional to its wavelength; the shorter the wavelength, the higher the energy of the light, or photon. In general, the absorption coefficient of polymer materials increases as the wavelength of light becomes shorter. This optical property is closely related to the molecular structure of the polymer material. The chemical bonding force between the transparent base material and the polymer material, which is the bond between the base material and the polymer material, is
Cut by light energy. As a result, by irradiating light energy from the back side of the polymer material formed on the transparent base material, only the irradiated portions can be selectively removed. Therefore, parts covered and buried with this polymer material can be removed.

However, the points to be considered in the present invention are:
Just because short-wavelength light has a large interaction with polymeric materials does not necessarily mean that short-wavelength light is advantageous to the present invention. This is because, as with polymeric materials, when the wavelength of light becomes shorter, the absorption coefficient of transparent substrates also tends to increase as a general tendency. As the wavelength of light becomes shorter, the proportion of light energy irradiated onto a polymer material through a transparent base material is absorbed by the transparent base material, or in other words, the rate at which it is immediately converted into thermal energy increases. Therefore, the energy input into the polymeric material is reduced. Therefore, the proportion of the total energy irradiated that is involved in peeling off the interface between the transparent substrate and the polymeric material is reduced. However, considering the chemical reaction, since the reaction temperature increases, the frequency of the reaction, in other words, the rate of the reaction naturally increases. The temperature during this reaction can be controlled not only by the irradiated light energy but also by actively controlling the temperature of the transparent substrate or polymer material. Thus, in the present invention, the conditions of the irradiated light energy, such as wavelength, power, irradiation time, irradiation area, temperature, etc., depend on the materials and shapes of the transparent base material and polymer material used. Therefore, those conditions are appropriately determined depending on the materials used.

0010

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings. FIG. 1 is a schematic diagram showing a method of repairing a wiring board. In the figure, 1 is a transparent base material, for example, a glass base material, and 2 is a wiring formed on the transparent base material, for example, indium-
Tin complex oxide (ITO; Indium Thin O
A thin film wiring 3 consisting of
SI chip, 4 is a bonding member that electrically connects the thin film wiring 2 and the component 3, such as solder; 5 is a polymeric material that covers or embeds the component 3, such as epoxy resin; 6 is an oscillation wavelength in the ultraviolet region; A laser oscillator, for example, an excimer laser oscillator; 7 is an optical system for focusing the excimer laser; 8 is a drive system for scanning the excimer laser or a glass substrate; 9 is an excimer laser ON/OFF, output, and drive system It is a controller that controls the

With this configuration, the light energy generated by the laser oscillator 6 is focused by the optical system 7 and irradiated from the back surface of the transparent base material 1 at the portion where the defective component 3 is located. As a result, as described above, the chemical bonding force between the transparent substrate and the polymeric material is severed by irradiation with high-energy light, so that the polymeric material is peeled off from the transparent substrate. Thereafter, the polymer material can be easily removed by selectively heating it. As heating means, heat tools such as soldering irons, lamps, hot air blowers, and lasers can be used.
Other heating means may also be used. A wiring board can be manufactured by removing the defective component 3 and then mounting and mounting a new component 3.

0012

[Effects of the Invention] As explained above, according to the method for manufacturing a wiring board of the present invention, optical energy such as a laser beam is selectively applied to the polymer material through the transparent base material, so that defects can be avoided. The polymer material can be removed only from parts, making it easy to replace them with parts that are in good working order. As a result, there is no effect on the transparent substrate, the thin film wiring formed on the wiring board, other polymer materials, or the parts covered or embedded therein. In addition, other parts can be reused as they are, contributing to lower manufacturing costs of wiring boards and, in turn, to lowering costs of liquid crystal display devices.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram of a method for manufacturing a wiring board according to the present invention.

FIG. 2 is a schematic explanatory diagram of a conventional wiring board manufacturing method.

FIG. 3 is a schematic exploded perspective view of a conventional liquid crystal device.

[Explanation of symbols]

1 Transparent base material 2 Thin film wiring 3 Parts 4　Joining member 5 Polymer materials 6 Laser oscillator 7. Optical system 8 Drive system 9 Controller

Claims (1)

[Claims] 1. Forming electrical thin film wiring on one main surface of a transparent base material having at least two main surfaces, disposing a component on the transparent base material in electrical connection with the thin film wiring, and disposing a component on the transparent base material, A method for manufacturing a wiring board in which thin film wiring and the components are buried or covered with a polymeric material, the method comprising irradiating the polymeric material with light energy from the other principal surface of the transparent substrate through the transparent substrate. By doing so, the polymer material near the interface between the polymer material and the transparent substrate is selectively photochemically or thermally altered, the polymer material is removed, and the parts are replaced. Characteristic wiring board manufacturing method.