JPH08204342A - Paste for multilayer wiring board and manufacture thereof - Google Patents

Abstract

PURPOSE: To stably maintain the paste printing amount and printing shape even in the case of continuously printing by strengthening the paste aggregating force. CONSTITUTION: The paste for a multilayer wiring board comprises an inorganic material made of at least one of a conductor material and an insulating material, and an organic vehicle containing polymer material and solvent. The polymer material is so formed of mixture of low polymerization resin and high polymerization resin that the aggregate force 16 of the paste 14 overcome viscous force 17 to be clearly separated from a mask plate 13. The inorganic material of the composition is 50 to 90wt.%, the vehicle is 10 to 50wt.%, the polymer material in the vehicle is 5 to 2Owt.%, and the solvent is 80 to 95wt.%. The low polymerization resin in the polymer material is 30 to 70wt.%, and the high polymerization resin is 30 to 70wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paste as a raw material for a multilayer wiring board for mounting an electronic component such as an LSI or an IC to form an electronic circuit, and a method for manufacturing the paste.

[0002]

2. Description of the Related Art With the recent development of low-temperature sintered glass / ceramic substrates, it has become possible to use at least one of Au, Ag, Cu and Pd for the wiring conductors and via conductors. Since these metals have lower conductor resistance and melting temperature than W and Mo that have been used for conventional ceramic multilayer wiring boards, a good quality multilayer wiring board can be manufactured at low cost using equipment with good safety. It can be manufactured.

As a method of manufacturing such a ceramic multilayer wiring board, there are a green sheet laminating method and a thick film printing method. The former is suitable for high stacking and can form a fine wiring pattern, but on the other hand, it has a drawback that the shrinkage of the substrate during firing tends to vary and the manufacturing yield is not good. on the other hand,
Since the latter has less shrinkage in the planar direction of the substrate during firing, it is possible to manufacture a multilayer wiring board with high yield, but on the other hand, a step due to wiring occurs on the surface of the board, so it is not suitable for high stacking and fine wiring patterns. There are drawbacks.

Printing of wiring conductors and formation of via conductors are generally performed according to the procedure shown in FIG. That is, in the case shown in FIG. 2A, the glass / ceramic green sheet 2 placed on the stage 1 is covered with the screen plate 3, and the conductive paste 4 supplied on the screen plate 3 is spread with the squeegee 5. Delay. Since the screen plate 3 is provided with an opening having a shape corresponding to the wiring pattern, a wiring conductor can be thick-film printed on the glass-ceramic green sheet 2. In addition, FIG.
Since the screen plate 3 in the example shown in FIG. 6 has the openings 7 corresponding to the via holes 6 which are the through holes of the glass / ceramic green sheet 2, the via holes are formed by printing the conductive paste 4 using the squeegee 5. Via conductors 8 can be formed in 6.

In the case shown in FIG. 2C, the glass-ceramic green sheet 2 itself has a film 9 on its surface, and this film 9 is provided with holes corresponding to the via holes 6. When the conductive paste 4 is printed through the film 6, the via conductor 8 can be obtained. In this case, in order to efficiently fill the conductive paste 4 in the via holes 6, vacuum suction is performed from the back surface side of the glass / ceramic green sheet 2.

In the printing of such a wiring conductor and the formation of a via conductor, the viscosity and thixotropy of the conductive paste should be controlled so that the conductor resistance does not change or bleeding occurs. Is important.
Further, with the miniaturization of wiring patterns, it has become important to manage the cohesive force of the conductive paste. As shown in FIG. 3, the viscous force of the conductive paste 4 acts in the direction indicated by the arrow 10, whereas the cohesive force acts in the direction indicated by the arrow 11. That is, the cohesive force of the conductive paste 4 acts in the direction of separating the paste 4 itself from the screen plate 3 against the viscous force.

[0007]

In forming the via conductor, the printing step shown in FIG. 4 (a) is performed, and then the via conductor shown in FIG. 4 (b) is formed.
The plate separation step shown in Fig. 4 is entered and the state shown in Fig. 4 (c) is entered. However, if the cohesive force of the conductive paste 4 is weak, the cohesive force of the paste 4 in the process of passing through the screen plate 3 is The viscous force cannot be overcome, and the portion 4a of the paste 4 remains on the screen plate 3.
Therefore, in the subsequent printing process, the paste 4
There are problems such as drooling and bleeding around the backside of the print.

Particularly, a conductive paste for a via conductor is often added with a shrinkage suppressing material such as Al ₂ O ₃ so that the shrinkage amount at the time of firing is close to the shrinkage amount of the glass / ceramic paste at the time of firing. . Therefore, the mixing ratio of the inorganic material in the paste becomes large, and when an organic vehicle similar to the wiring paste is used, the viscosity of the paste increases and filling printing of the via conductor becomes difficult.

Therefore, an organic vehicle is prepared by using a resin having a lower degree of polymerization than before. However, when a resin having a low degree of polymerization is used, the cohesive force of the paste itself is further weakened, so that the via conductor is filled. When printing on a mound
Problems such as who and bleeding appear more prominently.

Therefore, an object of the present invention is to provide a paste for a multilayer wiring board and a method for producing the same, which can strengthen the cohesive force of the paste and maintain a stable print amount and print shape of the paste even when the paste is continuously printed. To do.

[0011]

According to the present invention, in order to achieve the above-mentioned object, a composition comprising an inorganic material comprising at least one of a conductor material and an insulating material and an organic vehicle containing a polymer material and a solvent. Specifically, there is provided a paste for a multilayer wiring board, wherein the polymer material is a mixture of a low polymerization degree resin and a high polymerization degree resin.

The degree of polymerization of the low degree of polymerization resin is 1 by the number average degree of polymerization.
It is possible to make the degree of polymerization of the high-polymerization resin to be not less than 00 and less than 500 and not less than 500 and not more than 1000 in terms of number average degree of polymerization.

The polymer material may include at least one of ethyl cellulose, polyvinyl butyral and acrylic resin.

The composition contains 50 to 90% by weight of an inorganic material, 10 to 50% by weight of an organic vehicle, 5 to 20% by weight of a polymer material in an organic vehicle, and 80% of a solvent.
~ 95% by weight, and the low degree of polymerization resin in the polymer material is 3
The composition may be 0 to 70% by weight and the high-polymerization degree resin is 30 to 70% by weight.

A multilayer wiring board characterized by mixing an inorganic vehicle powder with an organic vehicle composed of a low polymerization degree resin and a solvent, and then mixing an organic vehicle composed of a high polymerization degree resin and a solvent. A method of making a paste is provided.

[0016]

In the present invention, the polymer material constituting the organic vehicle is composed of a mixture of a low-polymerization degree resin and a high-polymerization degree resin. Can be expanded in each of the zones. The high-polymerization degree resin has a function of strengthening the cohesive force of the paste, but if all the high-polymerization degree resin in the organic vehicle is replaced with the high-polymerization degree resin, the viscosity of the paste increases and printing becomes impossible. Therefore, since the low degree of polymerization resin is added, the degree of polymerization can be selected from a wide range centered on the average degree of polymerization of the resin contained in the conventional paste.
That is, the cohesive force of the paste can be increased while maintaining the same viscosity and thixotropy as those of the conventional paste.

[0017]

EXAMPLE An electroconductive paste in one example of the present invention is 41.7% by weight of Ag powder having an average particle size of 2.0 μm and glass-ceramic powder having an average particle size of 1.8 μm (manufactured by Nippon Electric Glass Co., Ltd., MLS). -25) 41.7% by weight, ethyl cellulose resin having a number average degree of polymerization of 250 as a binder (manufactured by Nisshin Kasei, Etocel N-10) 0.32% by weight, ethyl cellulose resin having a number average degree of polymerization of 900 (Nisshin Chemical composition, Etocel N-100) 0.48% by weight and terpineol 15.8% by weight as a solvent.

These materials are mixed and kneaded by a triple roll to prepare a conductive paste for via conductors.

During the mixing, a mixture of ethyl cellulose resin having a number average degree of polymerization of 250 and terpineol (first vehicle) and a mixture of ethyl cellulose resin having a number average degree of polymerization of 900 and terpineol (second vehicle) were mixed. It was found that the dispersibility of the inorganic powder in the paste can be made good by first preparing and mixing the first vehicle, the Ag powder and the glass-ceramic powder, and then mixing and kneading the second vehicle.

Table 1 shows the tack, which is the viscosity, thixo index, and cohesive force index of the conductive paste of this example.
The paste in this example is substantially equivalent in viscosity and thixo index as compared with the conventional via conductor paste, and the tack value, that is, the paste cohesive force is strengthened by about 1.5 times. I understand.

[0021]

[Table 1]

As a raw material for the glass-ceramic green sheet to be the insulating layer, a composition in which B ₂ O ₃ --SiO ₂ --PbO glass powder was mixed with Al ₂ O ₃ in a weight ratio of 45:55 (Nippon Glass Co., Ltd.) MLS-1000), polyvinyl butyral as a binder, butylbenzyl phthalate as a plasticizer, and toluene as a solvent were used. These were mixed to form a slurry, and a doctor blade method was applied to form a glass-ceramic green sheet (hereinafter abbreviated as a green sheet) on the film.

After punching is performed at the via conductor forming position of the green sheet to form a via hole, the surface of the green sheet is covered with a metal mask, and the conductive film is formed on the surface of the green sheet through the metal mask. The sex paste was printed. Since the metal mask has an opening at a position corresponding to the via hole, a part of the conductive paste spread by the squeegee is filled in the via hole. At this time, vacuum suction was performed from the back surface side of the green sheet through the sintered metal and the filter paper.

Next, after printing for forming the wiring conductor on the green sheet, a plurality of green sheets are laminated and formed into a laminated body by hot pressing, which is placed in a heating furnace and placed in the atmosphere. The binder was removed and the glass / ceramic was fired.

In the step of printing the conductive paste, as shown in FIG. 1A, the surface of the green sheet 12 is covered with a metal mask 13, and the conductive paste 14 provided on the metal mask 13 is spread with a squeegee 15. Let When the used conductive paste 14 has the characteristics shown in the upper part of Table 1, in the process of shifting to the state shown in FIG. 1C through the plate separating step shown in FIG. Therefore, the releasability of the conductive paste 14 from the metal mask 13 is improved.

This is a result of the cohesive force (indicated by the arrow 16) of the conductive paste 14 passing through the metal mask 13 overcoming the viscous force (indicated by the arrow 17), on the surface of the green sheet 12 and vias. It is possible to supply a predetermined amount of the conductive paste 14 in the holes to repeatedly form a conductor having a predetermined shape.

The conductive paste having the composition shown in the above-mentioned embodiment can be used not only for via conductors but also for wiring. When applied to 100 green sheets in a multilayer wiring board having a minimum wiring width of 0.75 mm, no trouble such as bleeding or broken wiring was observed. Further, in forming the via conductor, it was possible to print continuously in a via hole having a diameter of 0.05 mm to 0.15 mm without disturbance.

The paste and the manufacturing method thereof according to the present invention are not limited to the conductive paste, but can be applied to the insulating paste for forming the green sheet.

The inorganic material in the paste composition is 50 to 50%.
It is preferably selected from the range of 90% by weight. Further, the polymer material in the organic vehicle can be selected from the range of 5 to 20% by weight. Further, the low polymerization degree resin and the high polymerization degree resin in the polymer material can be selected from the range of 30 to 70% by weight, respectively. If the amount of the low-polymerization resin is extremely small compared to the high-polymerization resin, it becomes difficult to carry out the printing process.

[0030]

As described above, according to the present invention, since the polymer material in the organic vehicle is composed of the low-polymerization resin and the high-polymerization resin, the polymerization degree can be selected in a wide range and the same as in the conventional case. While maintaining viscosity and thixotropy, it is possible to strengthen the cohesive force of the paste, and therefore, it is possible to suppress the occurrence of obstacles such as the plate back and back of the paste during printing, bleeding, dripping, etc., and to manufacture a multilayer wiring board with good yield. can do.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a printing process using a conductive paste according to the present invention.

FIG. 2 is a schematic diagram of a printing process for forming a wiring conductor and a via conductor.

FIG. 3 is a diagram showing a relationship between a viscous force and a cohesive force of a printing paste which passes through a mask plate.

FIG. 4 is a schematic diagram of a printing process using a conventional conductive paste.

[Explanation of symbols]

 12 Green sheet 13 Metal mask 14 Conductive paste 16 Direction of cohesive force 17 Direction of viscous force

(72) Inventor Hiroyuki Otani 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Koichi Kumagai, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (5)

[Claims] 1. A composition comprising an inorganic material composed of at least one of a conductor material and an insulating material and an organic vehicle containing a polymer material and a solvent, wherein the polymer material is a low-polymerization resin and a high-polymerization resin. A paste for a multilayer wiring board, which comprises a mixture of 2. The multilayer wiring board according to claim 1, wherein the low degree of polymerization resin has a number average degree of polymerization of 100 or more and less than 500, and the high degree of polymerization resin has a number average degree of polymerization of 500 or more and 1000 or less. Paste. 3. The paste for a multilayer wiring board according to claim 1, wherein the polymer material contains at least one of ethyl cellulose, polyvinyl butyral and acrylic resin. 4. The composition contains 50 to 90% by weight of an inorganic material, 10 to 50% by weight of an organic vehicle, 5 to 20% by weight of a polymer material in an organic vehicle, and 80% of a solvent.
~ 95% by weight, and the low degree of polymerization resin in the polymer material is 3
The paste for a multilayer wiring board according to claim 1, wherein 0 to 70% by weight and the high-polymerization degree resin are 30 to 70% by weight. 5. A multi-layer wiring board characterized by mixing an inorganic vehicle powder with an organic vehicle composed of a low polymerization resin and a solvent, and then mixing an organic vehicle composed of a high polymerization resin and a solvent. Paste manufacturing method.