JP2007208293A - Method for setting thickness of conductor pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for setting thicknesses of conductor patterns in a method of manufacturing a ceramic multilayer substrate for preventing the occurrence of defective printing of subsequently formed conductor patterns by flattening the surface of a burned body. <P>SOLUTION: The method of manufacturing a ceramic multilayer substrate includes steps of: printing conductor patterns 12, 12a on a plurality of ceramic green sheets 11, 11a, 11b; laminating the ceramic green sheets; and burning the laminated sheets while applying pressure thereto to form the ceramic multilayer substrate. The method for setting the thicknesses of the conductor patterns therefor is to allow the thicknesses of the conductor patterns 12, 12a to be equivalent to the thickness deformation of the ceramic green sheets 11, 11a, 11b in printing the conductor patterns 12, 12a during the steps of laminating, applying pressure, and burning. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for setting a thickness of a conductor pattern. In particular, the present invention relates to a method for setting the thickness of a conductor pattern suitable for use in a method for manufacturing a ceramic multilayer substrate.

  With reference to FIGS. 2A to 2C, a method of manufacturing a conventional ceramic multilayer substrate by a method of laminating ceramic green sheets will be described. As shown in FIG. 2A, through holes (not shown) are formed in each of a plurality (four in this example) of ceramic green sheets 51, 51a, 51b, 51c using a press die or the like. Then, via conductors are filled in the through holes by screen printing to form via conductors, and at the same time, conductor patterns (not shown) are formed by screen printing using the conductor paste. Next, as shown in FIG. 2B, these ceramic green sheets 51, 51a, 51b, 51c are overlapped to form a laminated body 52, and further, ceramic green sheets 51, The constraining ceramic green sheets 53 and 53a that are not sintered at the firing temperatures 51a, 51b, and 51c are superposed and fired while being pressed by the pressure body 54. Next, as shown in FIG. 2C, the ceramic ceramic sheets 53 and 53a for restraint are removed, and the fired body 55 is formed. The fired body 55 is further screen-printed with a conductor pattern (not shown) on the surface and fired to produce the ceramic multilayer substrate 50.

A method for manufacturing a ceramic multilayer substrate in which a conductor pattern is formed on the surface of a substrate after firing a laminate including a constraining ceramic green sheet under pressure is described in Japanese Patent Laid-Open No. 7-86743 (Patent Document 1). Yes.
JP 7-86743 A

  However, the conventional method for manufacturing a ceramic multilayer substrate as described above has the following problems.

  As shown in FIGS. 3A to 3C, for example, ceramic green sheets 61 and 61a on which conductor patterns 62 and 62a are printed and ceramic green sheets 61b (three ceramic green sheets are used in this example) are stacked. A ceramic multilayer substrate 60 formed by firing a laminate is a pressure body in which constraining ceramic green sheets 63, 63a that are not sintered at the firing temperature of the ceramic green sheets 61, 61a, 61b are placed on both sides of the laminate. Even if firing is performed while applying pressure at 64, the conductor pattern 62, 62a causes the outer surface side of the fired body 65 to bulge into a convex shape, resulting in irregularities on the surface. Due to the unevenness of the surface of the fired body 65, printing blur, pattern chipping, etc. occur in the formation of a post-fired conductor pattern (not shown) after firing, resulting in a decrease in yield. Unevenness is likely to occur on the surface of the fired body 65, particularly when the thickness of the ceramic green sheets 61, 61 a, 61 b is 100 μm or less.

  The present invention has been made in view of such circumstances, and provides a method for setting the thickness of a conductor pattern in a method for manufacturing a ceramic multilayer substrate that flattens the surface of a fired body and prevents the occurrence of defective printing of a retrofitted conductor pattern. The purpose is to do.

  In order to achieve the above object, a method for setting the thickness of a conductor pattern according to the present invention is formed by printing a conductor pattern on a plurality of ceramic green sheets, laminating the plurality of ceramic green sheets, and firing them while applying pressure. In the method for setting the thickness of the conductor pattern for the method of manufacturing a ceramic multilayer substrate, the thickness of the ceramic green sheet in the laminating, pressing and firing steps is determined when the conductor pattern is printed. Set to equivalent conductor thickness. As a result, the conductor thickness of the conductor pattern can be suppressed within the thickness deformation of the ceramic green sheet, so that the surface of the fired body can be flattened, and printing defects such as print bleeding and pattern chipping can occur. Can be prevented.

  Here, the ceramic green sheet is preferably made of a low-temperature fired ceramic that can be fired at 800 to 1000 ° C. Thereby, it is possible to perform firing while easily pressurizing using a constraining ceramic green sheet that is not sintered at the firing temperature of the ceramic green sheet.

  According to the present invention, since the conductor thickness of the conductor pattern can be suppressed within the thickness deformation amount of the ceramic green sheet, the surface of the fired body can be flattened, and post-printing such as printing bleeding and pattern chipping can be achieved. It is possible to prevent occurrence of defects at the time.

  Next, embodiments of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention. Here, FIGS. 1A to 1C are explanatory views of a method for manufacturing a ceramic multilayer substrate according to an embodiment of the present invention.

A method for manufacturing a ceramic multilayer substrate according to an embodiment of the present invention will be described with reference to FIGS. Here, a method for manufacturing a ceramic multilayer substrate using a low-temperature fired ceramic as the ceramic will be described. As shown in FIG. 1 (A), first, ceramic green sheets 11, 11a, 11b of low-temperature fired ceramics to be used (three ceramic green sheets are used in the present embodiment) are produced as follows. Is done. CaO—Al ₂ O ₃ —SiO ₂ —B ₂ O ₃ glass powder 50 to 65 wt% (preferably 60 wt%) and alumina powder 50 to 35 wt% (preferably 40 wt%) are mixed A low-temperature fired ceramic powder is prepared, and a solvent such as toluene, xylene, butanol, a binder such as polyvinyl butyral or acrylic resin, and a DOA (diethylhexyl adipate), for example, A plasticizer such as) is added and sufficiently kneaded to prepare a slurry, which is then formed into a sheet using a normal doctor blade method.

  Next, via holes (not shown) are drilled at predetermined positions of the ceramic green sheets 11, 11a, and 11b formed by cutting the sheet shape into predetermined dimensions using a punching die, an NC machine, or the like. Then, Ag-based conductor paste made of Ag, Ag-Pd, Ag-Pt, or the like is filled in the via holes of the ceramic green sheets 11, 11a, 11b of each layer by screen printing or the like to form via-hole conductors. Furthermore, on the ceramic green sheets 11 and 11a of the respective layers, conductor patterns 12 and 12a having a conductor thickness equal to or smaller than the thickness deformation of the ceramic green sheets 11, 11a and 11b are screen-printed using a conductor paste having the same composition. Form with. Note that a conductor pattern may be formed on the outer surface side of the uppermost ceramic green sheet 11b or the outer surface side of the lowermost ceramic green sheet 11, or a post-fired conductor pattern 16 (FIG. 1). (See (C)). Further, as the conductor paste, other low melting point metal pastes such as Cu type and Au type may be used in addition to the Ag type.

Next, as shown in FIG. 1 (B), ceramic green sheets 11, 11a, 11b are stacked one on top of the other, and further, the lower layer and the upper layer are not sintered at the firing temperature of the ceramic green sheets 11, 11a, 11b. The ceramic green sheets 13 and 13a are placed and stacked, and are sandwiched between porous insulating plates made of alumina, SiC or the like and pressed from both sides to apply a pressure of about 10 ⁵ to 10 ⁷ Pa. While firing at 800 to 1000 ° C., a fired body 15 (see FIG. 1C) is formed. In the fired body 15, since the conductor thickness of the conductor patterns 12, 12a is equal to or smaller than the thickness deformation amount of the ceramic green sheets 11, 11a, 11b, the conductors are embedded in the green sheets when the ceramic green sheets 11, 11a, 11b are laminated. In addition, since it is fired under pressure, it can be fired extremely flat. The constraining ceramic green sheets 13 and 13a used above are made of a ceramic for high temperature firing, such as alumina, magnesia, zirconia, etc., and a binder (for example, polyvinyl butyral, acrylic, nitrocellulose, etc.) is used for this ceramic powder. Resin), a solvent (for example, toluene, xylene, butanol, etc.) and a plasticizer, and kneaded sufficiently to prepare a slurry, which is formed into a sheet using a normal doctor blade method.

  The restraining ceramic green sheets 13 and 13a cannot be sintered unless heated to about 1300 to 1600 ° C. In addition, the restraining ceramic green sheets 13 and 13a do not contain a sintering aid such as silica, magnesia, or calcia, and thus are difficult to sinter. Therefore, if firing at 800-1000 ° C., the constraining ceramic green sheets 13, 13a remain unsintered. However, the organic matter such as the binder in the constraining ceramic green sheets 13 and 13a is thermally decomposed and scattered in the firing process, and only the inorganic ceramic powder remains.

  After firing, as shown in FIG. 1 (C), organic materials such as binder in the constraining ceramic green sheets 13 and 13a are scattered to remove the remaining ceramic powder, and the fired body 15 is produced. Then, a retrofitted conductor pattern 16 is formed on the surface of the fired body 15 by screen printing or the like using a low-melting point metal paste such as Ag, Ag-Pd, Ag-Pt, or the like, or Au or Cu. . In the formation of the post-attached conductor pattern 16, the surface of the fired body 15 is made extremely flat without being affected by the conductor patterns 12 and 12a formed inside the fired body 15. Thus, printing can be performed without causing defects such as pattern chipping. After printing, the post-conducting conductor pattern 16 is fired to produce the ceramic multilayer substrate 10 in a conductive state via the conductor patterns 12 and 12a and via-hole conductors (not shown).

In the above embodiment, a mixture of CaO—Al ₂ O ₃ —SiO ₂ —B ₂ O ₃ glass powder and alumina powder is used as the low-temperature fired ceramic material, but instead of this, MgO and _{-Al 2 O 3 -SiO 2 -B 2} O 3 based glass powder, and a mixture of alumina powder, glass powder SiO ₂ -B ₂ O ₃ -based, or a mixture of alumina powder, PbO-SiO ₂ -B _A low-temperature fired ceramic material that can be fired at 800 to 1000 ° C. such as a mixture of ₂ O ₃ glass powder and alumina powder or cordierite crystallized glass may be used. In addition, by using these low-temperature fired ceramic materials that can be fired at 800 to 1000 ° C. for the ceramic multilayer substrate, the ceramic green sheets for restraint that are not sintered at the firing temperature of the ceramic green sheets can be easily selected using alumina or the like. It is possible to perform firing while easily applying pressure.

The present invention is not limited to the ceramic multilayer substrate 10 made of a low-temperature fired ceramic, but may be applied to other ceramic multilayer substrates such as an alumina (Al ₂ O ₃ ) multilayer substrate and an aluminum nitride (AlN) multilayer substrate. it can.

  Further, in particular, when the thickness of the ceramic green sheets 11, 11a, 11b is usually 100 μm or less, the ratio between the conductor thickness of the conductor patterns 12, 12a and the thickness of the ceramic green sheets 11, 11a, 11b is close, so that it is flat. It becomes difficult to obtain the fired body 15. However, at this time, a condition when the thickness deformation amount of the ceramic green sheets 11, 11 a, 11 b is equal to or smaller than that of the ceramic green sheets 11 acts effectively, and the flat fired body 15 can be easily obtained.

(Example)
The present inventor compared the degree of unevenness on the surface of the fired body of the ceramic multilayer substrate produced by the manufacturing method according to the present invention and the degree of unevenness on the surface of the fired body of the ceramic multilayer substrate produced by the conventional manufacturing method. First, as a sample in the present invention, the thickness of the low-temperature fired ceramic green sheet is set to four types of 300, 200, 100, and 80 μm, and six low-temperature fired ceramic green sheets having the same thickness deformation amount are set as one unit. Six units were set in which the amount of deformation was changed to 30, 27, 18, 15, 9, and 7 μm. Using a conductor paste made of Ag, a conductor pattern having a size of 20 × 20 mm and having the same conductor thickness is formed by screen printing on five low-temperature fired ceramic green sheets, and a conductor pattern is not formed on the uppermost layer. Eight types of samples in which the conductor thickness of the conductor pattern was changed were prepared for the ceramic multilayer substrate on which the sheet was placed and six low-temperature fired ceramic green sheets were laminated at a pressure of 10 ⁵ Pa. Then, the surface roughness of the fired body of the ceramic multilayer substrate produced by the manufacturing method of the present invention is formed by laminating ceramic green sheets for restraint made of alumina on the lower layer and the upper layer on these samples and firing them while applying pressure. did. In addition to this, fired bodies of six types of ceramic multilayer substrates prepared by a conventional manufacturing method were prepared, and the surface irregularities were measured. The measurement results are shown in Table 1.

  As a result of measurement in the method of manufacturing the ceramic multilayer substrate of the present invention, the unevenness of the surface of the fired body of the ceramic multilayer substrate is found when the conductor thickness of the conductor pattern is equal to or smaller than the thickness deformation amount of the ceramic green sheet. It was confirmed that there was substantially no. Further, a large unevenness value was measured on the surface of the fired body of the ceramic multilayer substrate in which the conductor thickness of the conductor pattern in the conventional method for producing a ceramic multilayer substrate exceeded the thickness deformation amount of the ceramic green sheet.

  The thickness setting method of the first conductor pattern is a method of manufacturing a ceramic multilayer substrate in which a conductor pattern is printed on a plurality of ceramic green sheets, the plurality of ceramic green sheets are stacked, and fired while being pressed. In the method for setting the thickness of the conductor pattern for printing, when the conductor pattern is printed, the conductor pattern is set to a conductor thickness equivalent to the thickness deformation amount of the ceramic green sheet in the laminating, pressing and firing steps. The thickness setting method of the second conductor pattern is a method for manufacturing a ceramic multilayer substrate in which a conductor pattern is printed on a plurality of ceramic green sheets, the plurality of ceramic green sheets are laminated, and fired while being pressed. In the method for setting the thickness of the conductor pattern for printing, when the conductor pattern is printed, the conductor pattern is set to a conductor thickness smaller than the thickness deformation amount of the ceramic green sheet in the steps of lamination, pressing and firing. According to these conductor pattern thickness setting methods, the surface of the fired body can be flattened by pressing the conductor thickness of the conductor pattern into the thickness deformation amount of the ceramic green sheet. The occurrence of defects during printing can be prevented.

  In addition, the said embodiment disclosed this time is an illustration in all the points, Comprising: It is not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and includes all modifications within the scope and meaning equivalent to the terms of the claims.

(A)-(C) are explanatory drawings of the manufacturing method of the ceramic multilayer substrate which concerns on one embodiment of this invention, respectively. (A)-(C) are explanatory drawings of the manufacturing method of the conventional ceramic multilayer substrate, respectively. (A)-(C) is explanatory drawing of the problem of the ceramic multilayer substrate produced with the manufacturing method of the conventional ceramic multilayer substrate, respectively.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Ceramic multilayer substrate, 11, 11a, 11b Ceramic green sheet, 12, 12a Conductor pattern, 13, 13a Restraining ceramic green sheet, 14 Pressure body, 15 Fired body, 16 Retrofitted conductor pattern.

Claims (2)

In a method for setting the thickness of a conductor pattern for a method of manufacturing a ceramic multilayer substrate, wherein a conductor pattern is printed on a plurality of ceramic green sheets, the plurality of ceramic green sheets are laminated, and fired while being pressed.
A method for setting a thickness of a conductor pattern, wherein the conductor pattern is set to a conductor thickness equivalent to a thickness deformation amount of the ceramic green sheet in the laminating, pressing and firing steps when printing the conductor pattern. In a method for setting the thickness of a conductor pattern for a method of manufacturing a ceramic multilayer substrate, wherein a conductor pattern is printed on a plurality of ceramic green sheets, the plurality of ceramic green sheets are laminated, and fired while being pressed.
A method for setting a thickness of a conductor pattern, wherein the conductor pattern is set to a conductor thickness smaller than a thickness deformation amount of the ceramic green sheet in the steps of laminating, pressing and firing in printing the conductor pattern.

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