JP3567640B2 - Method for manufacturing thick film circuit board - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a thick film circuit board.
[0002]
[Prior art]
8 to 12 show a method of manufacturing a via portion in a conventional thick film circuit board (multilayer board). First, as shown in FIG. 9, a conductor paste is printed on the ceramic substrate 11 of FIG. 8, dried and fired to form a lower conductor 12 on the ceramic substrate 11. Then, as shown in FIG. 10, the insulating layer forming paste is printed on the ceramic substrate 11 including the lower conductor 12, dried and fired to form the insulating layer 13. At this time, in the insulating layer 13, a plurality of via holes 14 are simultaneously formed at arbitrary positions on the lower conductor 12. Thereafter, as shown in FIG. 11, a conductor paste is printed so as to fill the via hole 14, and the via hole conductor 15 is formed by drying and firing. Further, as shown in FIG. 12, a conductor paste is printed on the insulating layer 13, dried and baked to form an upper conductor 16, and the lower and upper conductors 12, 16 are electrically connected via the via-hole conductor 15. Connect to
[0003]
[Problems to be solved by the invention]
However, in the step of forming the insulating layer 13 on the lower conductor 12, when the insulating layer forming paste 13a is screen-printed as shown in FIG. 13, the insulating layer forming paste 13a is dripped into the via hole 14. The via passage is narrowed, and a conduction failure occurs between the upper conductor wiring and the lower conductor wiring. In the worst case, the via conductor becomes open.
[0004]
In order to prevent the insulating layer forming paste 13a from dripping into the via hole 14, printing, drying and baking of the insulating layer forming paste may be performed in plural times. As a result, the via passage becomes narrow, and conduction failure occurs.
[0005]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for manufacturing a thick-film circuit board, which can eliminate a problem such as filling of a via hole due to sagging.
[0006]
[Means for Solving the Problems]
According to the first aspect of the present invention, in the first step, the lower conductor is disposed on the insulating substrate, and in the second step, the via hole formed on the lower conductor is formed of a material that is vaporized by firing. A partial filling is arranged. Then, in the third step, the insulating layer forming paste is disposed on the lower conductor. At this time, since the via hole filling material is disposed in the via hole, the paste for forming the insulating layer does not drip in the via hole. Further, in the fourth step, the insulating layer is formed by baking, and the via hole portion filling body is removed. By the fifth step, the inside of the via hole is filled with the conductor, and the upper conductor is arranged on the insulating layer.
[0007]
In this way, the lower conductor is formed on the insulating substrate, the upper conductor is arranged on the lower conductor via the insulating layer, and the lower conductor and the upper conductor are electrically connected through the via hole formed in the insulating layer. A thickly connected circuit board is manufactured.
[0008]
When the paste for forming the via hole portion filling body is made of the binder component in the glass paste as the insulating layer forming paste as in claim 2, the via hole portion filling body is surely fired in the fourth step. Removed.
[0009]
In other words, when a material obtained by dissolving cellulose or acrylic resin in terpineol or butyl carbitol as a solvent is used as in claim 3, it is possible to surely vaporize and remove the via hole portion filler by baking in the fourth step. Can be.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 7 shows a thick film circuit board according to the present embodiment. A lower conductor 2 is arranged on a ceramic substrate (insulating substrate) 1 made of 96% alumina. The lower conductor 2 has a thickness of about 10 μm. An insulating layer 3 is formed on the lower conductor 2. The insulating layer 3 is formed by printing, drying, and firing a glass paste. A via hole 4 having a diameter of about 300 μm is formed in the insulating layer 3, and the via hole 4 is filled with a via hole conductor 5. The upper conductor 6 is disposed on the insulating layer 3 including the via hole conductor 5, and the lower conductor 2 and the upper conductor 6 are electrically connected by the via hole conductor 5.
[0011]
Next, a method of manufacturing the thick film circuit board will be described with reference to FIGS.
First, a ceramic substrate 1 shown in FIG. 1 is prepared. Then, as shown in FIG. 2, a conductor paste is screen-printed using a screen mask having a predetermined pattern for forming the lower conductor 2 on the ceramic substrate 1, and the paste is dried and fired. As the conductor paste, for example, a material mainly composed of silver (Ag) is used.
[0012]
Then, as shown in FIG. 3, a via-hole filling member 7 for preventing sagging is arranged in a via-hole forming portion (a region where a via hole is to be formed) on the lower layer conductor 2. In forming the via hole portion filling body 7, a paste composed of a resin component that burns or decomposes and evaporates during firing of the glass paste and a solvent that evaporates by heating and drying is used. In the present embodiment, the via-hole filling paste is composed of a binder component cellulose and a solvent terpineol in a glass paste, and the via-hole filling paste, that is, a paste obtained by dissolving cellulose in terpineol is printed and printed. The via hole portion filling body 7 is formed by drying. The via-hole filling member 7 has a cylindrical shape, and its diameter is about 300 μm.
[0013]
Note that the height of the via hole portion filling body 7 is preferably substantially the same as the height of the glass paste (indicated by 3a in FIG. 4).
Next, as shown in FIG. 4, a glass paste 3 a as an insulating layer forming paste is printed on the ceramic substrate 1 including the lower layer conductor 2. At this time, the via-hole filling member 7 does not cause dripping of the glass paste 3a into the via-hole. Further, after drying at 100 to 150 ° C., baking is performed at about 800 ° C. for 1 hour to form the insulating layer 3 as shown in FIG. At the time of this firing, the via hole portion filling body 7 is vaporized to form the via hole 4. This insulating layer forming step may be performed by one printing, drying, and firing, or may be performed by multiple printing, drying, and firing. In the case of performing multiple times, the thickness per one time is 25 μm. Degree. When the glass paste is printed a plurality of times, the via hole portion filling body 7 may be formed before each glass paste is printed.
[0014]
Then, as shown in FIG. 6, the via-hole conductor paste is filled (printed) in the via-hole 4 formed by removing the via-hole filling member 7, and dried and fired to form the via-hole conductor 5. Further, as shown in FIG. 7, a conductor paste for forming an upper conductor is printed on the insulating layer 3 including the via hole conductor 5 and dried and fired. This is performed a plurality of times to form the upper conductor 6. As a result, the lower and upper conductors 2 and 6 are electrically connected via the via hole conductor 5.
[0015]
As described above, the present embodiment has the following features.
(A) The lower conductor 2 is disposed on the ceramic substrate 1 (first step), and the via hole filling member 7 made of a material that is vaporized by firing is disposed in the via hole forming portion on the lower conductor 2 (second step). Step), a glass paste 3a is disposed on the lower conductor 2 (third step), and the insulating layer 3 is formed by firing, and the via-hole filler 7 is removed (fourth step). And the upper conductor 6 was arranged on the insulating layer 3. Therefore, in the third step, since the via-hole filling member 7 is disposed in the via-hole portion, the glass paste 3a does not sag in the via-hole portion, and problems such as burying of the via hole due to the sag are eliminated. In other words, if printing, drying, and baking of the insulating layer forming paste are performed a plurality of times in order to prevent the insulating layer forming paste from dripping into the via holes, conduction errors may occur due to printing misalignment. In the embodiment, the method is not used, and no conduction failure occurs.
(B) As a paste for forming the via-hole-portion filling body 7, a paste obtained by dissolving cellulose with terpineol as a solvent was used. That is, it was composed of the binder component in the glass paste 3a as the insulating layer forming paste. Therefore, the via-hole filling member 7 can be reliably vaporized and removed at the time of firing the glass paste 3a.
[0016]
In the above embodiment, the via hole filling paste obtained by dissolving cellulose in terpineol was used.In addition to this, cellulose dissolved in butyl carbitol, and acrylic resin dissolved in terpineol or butyl carbitol Can be used as a paste for filling a via hole portion, the same effect can be obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view for explaining a manufacturing process of a thick-film circuit board in an embodiment.
FIG. 2 is a cross-sectional view for explaining a manufacturing process of the thick film circuit board in the embodiment.
FIG. 3 is a cross-sectional view for explaining a manufacturing process of the thick film circuit board in the embodiment.
FIG. 4 is a cross-sectional view for explaining a manufacturing process of the thick film circuit board in the embodiment.
FIG. 5 is a cross-sectional view for explaining a manufacturing process of the thick film circuit board in the embodiment.
FIG. 6 is a sectional view for illustrating a manufacturing process of the thick film circuit board in the embodiment.
FIG. 7 is a sectional view for illustrating a manufacturing process of the thick-film circuit board in the embodiment.
FIG. 8 is a cross-sectional view illustrating a manufacturing process of a conventional thick film circuit board.
FIG. 9 is a cross-sectional view for explaining a manufacturing process of a conventional thick film circuit board.
FIG. 10 is a cross-sectional view for explaining a manufacturing process of a conventional thick film circuit board.
FIG. 11 is a cross-sectional view for explaining a manufacturing process of a conventional thick film circuit board.
FIG. 12 is a cross-sectional view illustrating a manufacturing process of a conventional thick film circuit board.
FIG. 13 is a cross-sectional view for explaining a manufacturing process of a conventional thick film circuit board.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Ceramic substrate as an insulating substrate, 2 ... Lower conductor, 3 ... Insulating layer, 3a ... Glass paste as an insulating layer forming paste, 4 ... Via hole, 5 ... Via hole conductor, 6 ... Upper conductor, 7 ... Filling of via hole part body.

Claims (3)

A lower conductor is formed on an insulating substrate, an upper conductor is arranged on the lower conductor via an insulating layer, and the lower conductor and the upper conductor are electrically connected to each other through a via hole formed in the insulating layer. A method of manufacturing a thick film circuit board,
A first step of disposing a lower conductor on an insulating substrate;
A second step of disposing a via-hole filling body made of a material that is vaporized by firing in the via-hole forming portion on the lower conductor;
A third step of disposing an insulating layer forming paste on the lower conductor;
A fourth step of forming the insulating layer by firing and removing the via hole portion filling body;
Filling the via hole with a conductor and arranging an upper conductor on the insulating layer. 2. The method for manufacturing a thick film circuit board according to claim 1, wherein the paste for forming the via hole portion filling body is composed of a binder component in a glass paste as an insulating layer forming paste. 3. The method for manufacturing a thick film circuit board according to claim 2, wherein the paste for forming the via hole portion filling body is obtained by dissolving cellulose or acrylic resin in a solvent such as terpineol or butyl carbitol.

Images