JP4948459B2 - Paste composition - Google Patents

Description

  The present invention relates to a paste composition suitable for screen printing in the production of a ceramic multilayer circuit board.

  Ceramic multilayer circuit boards are widely used as high-density mounting circuit boards. The ceramic multilayer circuit board is manufactured by the following procedure by the ceramic green sheet lamination method.

  First, a ceramic green sheet is obtained by forming a slurry comprising ceramic fine powder and an organic binder, a plasticizer, a solvent, and the like by a known forming method such as a doctor blade method or a calendar method. Next, via holes for interlayer connection are formed in the plurality of ceramic green sheets thus obtained by punching, laser processing, or the like. Next, a conductive paste is filled in the via hole of each ceramic green sheet by hole printing to form a via hole conductor. Thereafter, a wiring pattern made of a conductive paste, an insulating layer made of an insulating paste, or the like is printed on each ceramic green sheet on which via-hole conductors are formed using a screen printer. Further, a plurality of ceramic green sheets printed with a wiring pattern made of a conductive paste or an insulating layer made of an insulating paste are laminated and pressure-bonded. Finally, a ceramic multilayer circuit board is manufactured by simultaneously firing the laminated ceramic green sheets.

  However, when a wiring pattern or an insulating layer is printed with a paste composition using a screen printing machine, if the same screen plate making is used repeatedly, bleeding occurs between the wiring patterns and at the corners of the wiring pattern. Sometimes. In order to eliminate the bleeding, work such as wiping the screen plate is being performed. As a result, the productivity of screen printing is reduced while the manufacturing cost of the ceramic multilayer circuit board is increased.

As for this type of technology, Patent Document 1 discloses, as a conductive paste for forming a via-hole conductor, 10 to 30 parts by weight of an organic vehicle and 0.5 to 10 parts by weight of a fatty acid amide with respect to 100 parts by weight of conductive powder. The electroconductive paste which mix | blended the part is disclosed.
JP 2005-209681 A

  In Patent Document 1, since fatty acid amide acts to impart thixotropy to the conductive paste, by adding 0.5 to 10 parts by weight of fatty acid amide to 100 parts by weight of the conductive powder, the via hole is formed. It is described that no poor filling of the conductive paste occurs. On the other hand, in recent years, the wiring of a ceramic multilayer circuit board tends to be thinned and it is required to form a fine wiring pattern. In order to satisfy such a requirement, as described in Patent Document 1, it is not sufficient to add a fatty acid amide to the conductive powder.

  The present invention has been made in view of such problems of the prior art, and its purpose is to prevent the occurrence of bleeding in the screen-printed print pattern even when repeated printing is performed on the same screen plate making. An object of the present invention is to provide a paste composition capable of forming a fine wiring pattern.

  In order to achieve the above object, the gist of the present invention is that a paste composition comprising an inorganic filler, a cellulose resin, a butyral resin, dihydroterpineol, and a fatty acid amide contains 60.0 to 90.0% by weight of an inorganic filler; 0 to 5.0 wt% cellulose resin, 0.1 to 1.0 wt% butyral resin, 8.8 to 31.0 wt% dihydroterpineol, and 0.1 to 3.0 wt% It consists of fatty acid amides, and is characterized by a total of 100.0% by weight of the above compounds.

  ADVANTAGE OF THE INVENTION According to this invention, even if it prints repeatedly by the same screen platemaking, the paste composition which does not generate | occur | produce a screen-printed printing pattern and can form a fine wiring pattern can be provided.

FIG. 1 is a longitudinal sectional view showing an example of a low-temperature fired ceramic multilayer circuit board manufactured in the manufacturing process of this embodiment, and FIG. 2 is a flowchart showing the flow of the manufacturing process of this embodiment. Hereinafter, it demonstrates in order of a manufacturing process.
(1) Formation of Green Sheet First, a ceramic green sheet 1 for a low-temperature fired ceramic multilayer circuit board shown in FIG. 1 is tape-formed by using a low-temperature fired ceramic slurry by a doctor blade method or the like. In this case, as the ceramic, for example, a mixture of MgO—CaO—SiO ₂ -based crystallized glass 50 to 65 wt% and alumina 35 to 50 wt% can be used, but is not limited thereto. In addition, any low-temperature fired ceramic material that can be fired at 800 to 1000 ° C., such as a mixture of MgO—SiO ₂ —B ₂ O ₃ crystallized glass and alumina, can be used.
(2) Cutting of green sheet and drilling of via hole After this, the ceramic green sheet 1 tape-formed is cut to a predetermined size, and then via holes 2 and 3 are punched at predetermined positions as shown in FIG. . The via hole 3 having a larger diameter is a via hole that forms a thermal via for dissipating heat of a mounted electronic component (not shown), and the via hole 2 having a smaller diameter is a via hole that connects the wiring patterns 4 between the layers. A via hole that forms a conductor.
(3) Filling printing of conductive paste in via hole and printing of wiring pattern and insulating layer Thereafter, in FIG. 1, filling printing of via hole 2, 3 and interlayer wiring pattern 4, surface wiring pattern 5, back wiring pattern 6, component The mounting land 7 is printed using, for example, an Ag-based conductive paste having a composition described later. An insulating layer is printed on the surface layer wiring pattern 5 using an insulating paste obtained by using a mixture of glass and metal oxide as a paste, if necessary, like a green sheet.

  The conductive paste used in this printing can use Ag, Au, Pt, Pd, Cu, Ni, Fe, or the like as the conductive powder (conductive inorganic filler). Addition of Pd or Pt can be expected to improve solder resistance and suppress sintering. The content of the conductive powder (conductive inorganic filler) in the conductive paste is preferably 60.0 to 90.0% by weight. This is because if the conductive inorganic filler is less than 60.0% by weight, the electrical resistance value of the printed conductor increases and the electrical characteristics cannot be stabilized. On the other hand, when the conductive inorganic filler exceeds 90.0% by weight, the fluidity of the paste is insufficient, poor filling of the via hole occurs, and a good wiring pattern cannot be formed.

  The content of the insulating inorganic filler (glass powder, metal oxide, etc.) in the insulating paste is preferably 60.0 to 90.0% by weight, more preferably 65.0 to 75.0% by weight. When the insulating inorganic filler is less than 60.0% by weight, the insulating film after firing is too thin and the insulating effect becomes poor. On the other hand, if the insulating inorganic filler exceeds 90.0% by weight, the fluidity of the paste becomes poor, and pinholes are generated after printing, causing poor insulation.

  The cellulose resin is not limited, but ethyl cellulose, methyl cellulose and the like can be used.

  The butyral resin preferably has a composition having a butyral group of 60 to 70 mol% and an acetyl group of 3 mol% or less and a low polymerization degree of 250 to 400.

  The fatty acid amide is not limited, but stearic acid dimethylaminopropylamide and the like can be used.

A paste can be prepared by sufficiently kneading and dispersing a compound having a predetermined composition using a mixing device such as a three-roll mill.
(4) Lamination / crimping After printing is finished, as shown in FIG. 1, green sheets 1 of each layer are laminated, and this laminate is thermocompression bonded under conditions of 60 to 150 ° C. and 0.1 to 30 MPa, for example. Turn into.
(5) Firing After that, the laminate of the green sheet 1 shown in FIG. 1 is heated at a rate of temperature rise of about 10 ° C./min, firing peak temperature = 800 to 1000 ° C. (preferably around 900 ° C.), and 10 to 10 at the peak temperature. By firing in an air atmosphere under a condition of holding for 30 minutes, the laminate of the green sheet 1 is filled with an interlayer wiring pattern 4, a surface wiring pattern 5, a back wiring pattern 6, a component mounting land 7, and via holes 2 and 3 filling conductors. At the same time, it can be fired to produce a low-temperature fired ceramic multilayer circuit board.

  In addition, after the alumina green sheet is laminated on both surfaces of the laminate of the green sheet 1 in the firing step and fired at 800 to 1000 ° C. while pressing the laminate in this state, the alumina green sheet remains from both sides of the fired substrate. The material can be removed to produce a low-temperature fired ceramic multilayer circuit board. According to this baking method, an advantage that the dimensional accuracy of the substrate after baking can be improved by reducing the baking shrinkage amount of the substrate can be expected.

A paste was prepared by kneading the compounds shown in Table 1 and Table 2 (weight%) using a three-roll mill, and as a ceramic green sheet, 60% by weight of MgO—CaO—SiO ₂ crystallized glass. A 1 mm thick material mixed with 40% by weight of alumina was used.

  The green sheet was cut into 30 mm square to prepare a sample substrate. And after printing the printing pattern 8 for bleeding evaluation as shown in FIG. 3 on the sample board | substrate 9 by screen printing using the paste of the mixing | blending of each Example and comparative example which are shown in the following Table 1 and Table 2. Then, drying was performed at 120 ° C. for 10 minutes, and whether or not bleeding occurred between the printed patterns and at the corners of the printed patterns and the state of the paste film after drying were observed. Furthermore, the sample substrate on which the printed pattern for evaluation of bleeding after drying was formed was baked in a belt-type baking furnace under the conditions of a peak temperature of 900 ° C. and a peak temperature holding time of 20 minutes, and the baked conductor film and insulation The film was observed. Table 1 and Table 2 show the presence or absence of bleeding of the printed pattern 8 for bleeding evaluation after drying and the observation results of the paste film, and the observation results of the conductor film and insulating film after baking.

表１に示すように、本発明の実施例１ないし１６のペーストは、本発明の範囲内の適正な配合からなるので、滲み評価用印刷パターンに全く滲みは発生せず、乾燥後および焼成後の導体膜と絶縁膜の外観も良好であった。

As shown in Table 1, since the pastes of Examples 1 to 16 of the present invention consisted of proper blends within the scope of the present invention, no bleeding occurred in the printing pattern for bleeding evaluation, after drying and after baking. The appearances of the conductor film and the insulating film were also good.

  However, in Comparative Example 1, since there was too much ethyl cellulose, the conductive film after firing became porous.

  Moreover, since the comparative example 2 had too little ethylcellulose and dihydroterpineol, the conductor film after drying and baking was faded.

  Moreover, since the comparative example 3 had too much butyral resin, the paste was strong, and stringing was seen in the conductor film after drying and baking.

  In Comparative Example 4, since a butyral resin was not blended at all, bleeding occurred in the printing pattern for bleeding evaluation.

  Further, in Comparative Example 5, since there was too much dihydroterpineol, bleeding occurred in the printing pattern for bleeding evaluation, and the conductor film after firing was too thin.

  Further, in Comparative Example 6, since there was too much dimethylaminopropylamide stearate, cracking was observed in the fired conductor film due to poor debinding.

  Furthermore, in Comparative Example 7, since dimethylaminopropylamide stearate was not blended at all, bleeding occurred in the printing pattern for bleeding evaluation.

  In Comparative Example 8, since terpineol was used as a solvent instead of dihydroterpineol, bleeding occurred in the bleeding evaluation print pattern.

In Comparative Examples 9 to 13, since stearic acid was used in place of dimethylaminopropylamide stearate, bleeding occurred in the print pattern for bleeding evaluation.
<Viscosity characteristics>
Next, since the test which compares a viscosity characteristic was done about the paste of this invention of the mixing | blending of Example 5 in Table 1, and the paste of the mixing | blending of the comparative example 4 in Table 2, it demonstrates below.

  The test was carried out using a cone plate type rotational viscometer (Brookfield's product name is “DV-III”) at a rotational speed of 1 rpm, 2.5 rpm, 5 rpm, 10 rpm, 5 rpm, 2.5 rpm, Viscosity at the number of revolutions (Pa · s) of the arithmetic average value of the values after 2 minutes at each number of revolutions, changing in steps of 1 rpm, 2.5 rpm, 5 rpm, 10 rpm, 5 rpm, 2.5 rpm, and 1 rpm. It was. The results of the viscosity characteristic comparison test are shown in FIG. 4 with the rotational speed (rpm) as the horizontal axis and the viscosity (Pa · s) as the vertical axis.

  As can be seen from FIG. 4, the paste (symbol ◯) of the present invention has a good return of viscosity at each rotation speed, and the decrease in viscosity decreases as the rotation speed increases.

  On the other hand, the paste of the comparative example (symbol ●) shows little return of viscosity at each rotation speed, and the viscosity clearly decreases as the rotation speed increases, and this tendency does not change even at high rotation speed. Since the conventional paste composition has a viscosity characteristic similar to that of the paste of the comparative example of FIG. 4, bleeding is likely to occur when screen printing a wiring pattern or an insulating layer, and in particular, using the same screen plate making Bleeding tends to increase when printing repeatedly.

  The present invention provides a paste material that satisfies the requirements of fine and precise printability in response to the demands for multi-functionalization, complexization, downsizing of wiring due to downsizing, and the increase in the number of chips in recent years. Yes.

It is a figure which shows typically the cross section of an example of the low-temperature baking ceramic multilayer circuit board manufactured at the manufacturing process of this embodiment. It is a flowchart of an example of the manufacturing process of a low-temperature baking ceramic multilayer circuit board. It is a figure which shows the printing pattern for bleeding evaluation. It is a figure which shows the viscosity characteristic of the paste of this invention, and the paste of a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Green sheet 2 Via hole 3 Via hole 4 Interlayer wiring pattern 5 Surface layer wiring pattern 6 Back surface wiring pattern 7 Component mounting land 8 Print pattern for bleeding evaluation 9 Sample substrate

Claims (1)

In a paste composition comprising an inorganic filler, a resin component, a solvent and a fatty acid amide,
The inorganic filler is a conductive inorganic filler or an insulating inorganic filler,
The resin component is a cellulose resin and a butyral resin;
The solvent is dihydroterpineol,
When the total paste composition is 100.0% by weight, the inorganic filler content is 60.0 to 90.0% by weight , and the cellulose resin content is 1.0 to 5.0%. The butyral resin content is 0.1 to 1.0% by weight , the dihydroterpineol content is 8.8 to 31.0% by weight , and the fatty acid amide content is paste composition characterized in that 0.1 to not be 3.0 wt%.

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