JPS5929160B2 - Manufacturing method of wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a wiring board, and more particularly to a method of manufacturing a wiring board that can produce a high-density, low-cost wiring board.

In order to miniaturize and improve the performance of electronic devices, a mounting method in which a large number of bare LSI chips are mounted on a ceramic wiring board (hereinafter referred to as a "ceramic board") is attracting attention.

A thick film multilayer method is generally used to form the wiring layer of a ceramic board.

In this method, a metal or plastic mesh is coated with a photosensitive resin, and the resin is exposed and developed by shining light through a photomask with a predetermined wiring pattern formed thereon, thereby creating a printing screen having a predetermined wiring pattern. Next, a thick film paste of a conductor such as Ag-Pd or an insulator such as crystallized glass is printed on the ceramic plate through this screen to form a predetermined thick film paste pattern. After that, 1
Dry at 20-150°C and bake at about 800-1000°C. Note that in the case of multilayering, the processes of conductor printing and firing and insulator printing and firing are repeated. However, since this conventional thick film multilayer method uses a screen, it has the disadvantage that the width of the wiring pattern cannot be made sufficiently narrow.

In other words, in view of the required thickness of the conductor, the repeated use of the screen, etc., at present, a screen of approximately 300 mesh or less is used, and the width of the conductor is limited to 0.11 gt.
Furthermore, since this method uses a photomask to form the wiring pattern, it also has the disadvantage of high costs in small-scale production. Furthermore, conventionally, there is also a force method using a photosensitive thick film paste as a thick film paste for forming a high-density pattern.

In this case, a photosensitive thick film paste is applied to the entire surface of the ceramic plate, exposed through a photomask, developed to form a pattern of the thick film paste, and then baked in a conventional manner to obtain a wiring pattern. By the way, photosensitive thick film paste is useful as an insulator, but in the case of conductors, it generally has very poor light transmittance, so it is difficult to form high-density patterns on conductors with normal thickness using this method. .

Further, since a photomask is used, the disadvantage of high cost in small-scale production is the same as that of the thick film multilayer method described above. The present invention has been made in view of the above-mentioned actual situation in the prior art, and its purpose is to provide a method for manufacturing a wiring board that can obtain a thick film wiring pattern with high density and without using a photomask. It is about providing. In order to achieve this object, the main feature of the present invention is to form a wiring pattern by irradiating a thick film paste coated on a ceramic plate with a laser beam, and then firing it in a furnace.

It should be noted that if only the laser beam is irradiated, the peripheral portion of the conductor will be defective in baking and the desired conductive properties cannot be obtained, so it is essential to bake it in a furnace.

Hereinafter, the method for manufacturing a wiring board according to the present invention will be explained in detail based on the drawings.

FIG. 1 is an explanatory view showing the first aspect of the present invention, FIG. 1a is a block diagram showing the manufacturing process, and FIG. 1b is a side sectional view showing the manufacturing process. In addition, each of A to 2 in FIG. 1A corresponds to each of A to 2 in FIG. 1B. Further, in FIG. 1b, 1 is a ceramic board, 2 is a thick film paste, and 3 is a wiring pattern. First, as shown in each A and B of FIG. 1 is placed, and the thick film paste 2 is partially fired by irradiation with a laser beam as shown at the opening to form a predetermined wiring pattern 3. Next, as shown in c, the thick film paste 2 in the area not irradiated with the laser beam is dissolved using a suitable solvent. Finally, as shown in step 2, the material is fired using a conventional belt furnace or the like in order to complete the sintering and obtain the desired conductivity. In this way, a wiring board is obtained. Next, a specific example of manufacturing a wiring board using the method according to the first invention described above will be described.

In this specific example, the ceramic plate 1 has a purity of 96
% and a thickness of 111Q was used. Then, a silver-platinum paste manufactured by DuPont (Catalog No. 9770) was printed on the entire surface of this alumina substrate using a 325 mesh screen and dried at 150° C. for 15 minutes. Next, this board is placed on a table that moves in the X-Y direction, and the YAG
Continuous output 50W using laser, diameter approximately 0.0571iR
The thick film paste was irradiated with a laser beam of . The moving speed of the substrate at this time was set to 1 m/min. Next, the substrate irradiated with the laser beam was immersed in ethylene trichloride, and ultrasonic waves were applied to dissolve the thick film paste in the areas not irradiated with the laser beam. Finally, it was fired at a maximum temperature of 900°C using a belt furnace. Through the above steps, a wiring board having a wiring pattern with a width of 0.1 m or less was obtained. FIG. 2 is an explanatory view showing the second invention of the present invention, FIG. 2a is a block diagram showing the manufacturing process, and FIG. 2b is a side sectional view showing the manufacturing process.

This second invention shows a method for performing multilayer wiring. Note that each of I to I in Fig. 2a is the same as Fig. 2b.
It corresponds to each of I to I in . Figure 2b
, 4 is a ceramic board, 5 is a thick film conductor paste,
6 is a wiring pattern, 7 is a thick film insulator paste, 8 is a through hole, and 9 is a thick film conductor paste. In addition, Fig. 2 A, b
Steps I to C in FIG.
Since this is the same as (c), the explanation will be omitted. In this second invention, a thick film insulating paste 7 is applied to the entire surface of the ceramic board 4 on which the wiring pattern 6 is formed as shown in C.
Apply.

As the thick film insulating paste 7, for example, a paste manufactured by DuPont, Catalog 9950 is used. Next, as shown in E, approximately 800 to 1
Fire at 000°C. Then, as shown in Fig. 5, a laser beam is irradiated to a predetermined position to open a through hole 8. Note that in order to prevent the lower wiring pattern 6 from dissolving at this time, it is desirable that the material of the wiring pattern 6 be copper.
Next, thick film conductor paste 9 is applied to the entire surface as shown in FIG.
Apply. Repeat the following steps as necessary. In this way, a multilayer wiring board is obtained. Note that instead of the second thick film insulator paste application step in the second aspect of the invention described above, a photosensitive thick film insulator paste may be applied.

In this case, as the photosensitive thick film insulating paste, for example, FODEL (trade name) manufactured by DuPont is used. Then, after exposing it to light through a photomask, it is developed,
A through hole similar to through hole 8 in FIG. 2b is formed. This is then adjusted to about 800-1 to obtain the desired conductive properties.
After firing at 000°C, the process shown in Figure 2 is started, and the following steps are repeated as necessary. Even in this manner, a multilayer wiring board can be obtained. As explained above, in the method for manufacturing a wiring board of the present invention, since the pattern is formed by irradiating a laser beam, a wiring board having a thin wiring pattern can be obtained, and moreover, when forming the wiring pattern, Since no photomask is used, it is possible to manufacture at a lower cost than conventional methods.

Further, by firing in a furnace after laser beam irradiation, the peripheral part of the conductor can be completely baked and desired conductive properties can be obtained.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the first invention of the method for manufacturing a wiring board of the present invention, FIG. 1a is a block diagram showing the manufacturing process, and FIG. 1b is a side sectional view showing the manufacturing process. FIG. 2 is an explanatory view showing the second aspect of the present invention, FIG. 2a is a block diagram showing the manufacturing process, and FIG. 2b is a side sectional view showing the manufacturing process. 1, 4... Ceramic board, 2... Thick film paste, 3, 6... Wiring pattern, 5, 9...
...Thick film conductor paste, 7...Thick film insulator paste, 8...Sulfonate.

Claims (1)

[Claims] 1. Covering a substrate with a thick film paste, irradiating the thick film paste with a laser beam, melting and removing the thick film paste in areas not irradiated with the laser beam to form a predetermined pattern, and then A method for manufacturing a wiring board, characterized by firing in a furnace. 2 Cover the substrate with thick film conductor paste, irradiate the thick film conductor paste with a laser beam, dissolve and remove the thick film conductor paste in the areas not irradiated with the laser beam, and then form a predetermined wiring pattern. 1. A method of manufacturing a wiring board, comprising: coating a wiring pattern and the surface of a board with a thick film insulating paste, firing the paste in a furnace, and then drilling holes at predetermined positions using a laser beam. 3 Cover the substrate with thick film conductor paste, irradiate the thick film conductor paste with a laser beam, dissolve and remove the thick film conductor paste in the areas not irradiated with the laser beam, and then form a predetermined wiring pattern. A method for manufacturing a wiring board, which comprises applying a photosensitive thick film insulating paste to a wiring pattern and the surface of a substrate, exposing and developing the paste to make holes, and then baking it in a furnace.