JP6420088B2 - Manufacturing method of ceramic multilayer wiring board - Google Patents

Description

  The present invention relates to a method for manufacturing a ceramic multilayer wiring board having a structure in which a plurality of inner layer electrodes and a plurality of ceramic insulating layers are laminated to form a multilayer.

  In recent years, semiconductor integrated circuit elements (IC chips) used as computer microprocessors and the like have become increasingly faster and more functional, with an accompanying increase in the number of terminals and a tendency to narrow the pitch between terminals. . In general, a large number of terminals are densely arranged in an array on the bottom surface of an IC chip. An electronic component inspection wiring board is used for inspection of electronic components such as IC chips.

  As a wiring board for electronic component inspection, a ceramic multilayer wiring board having a structure in which a plurality of inner layer electrodes and a plurality of ceramic insulating layers are laminated to be multilayered has been put into practical use. Each ceramic insulating layer is provided with a plurality of via conductors, and the inner layer electrodes are connected to each other by via conductors. Further, as shown in FIG. 9, on the surface of the ceramic insulating layer 101, a plurality of island conductors 102 connected to a plurality of via conductors and a plain conductor 103 surrounding the plurality of island conductors 102 are provided. , Formed as an inner layer electrode. These conductors 102 and 103 are usually formed by printing (screen printing or the like) (see, for example, Patent Document 1).

Japanese Patent No. 3570242 ([0003] etc.)

  By the way, since the plain conductor 103 is a power source or ground conductor, a large current flows through the plane conductor 103. However, when the conductors 102 and 103 are formed by the above-described method (printing), the island-like conductor 102 and the plain-like conductor 103 may be short-circuited due to printing bleeding. There is a need. Moreover, when the pitch between the adjacent island conductors 102 becomes narrow, the island conductors 102 cannot be individually surrounded by the plane conductor 103. From the above, since it is difficult to increase the area of the plane conductor 103, there is a problem that the impedance of the plane conductor 103 is increased.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for manufacturing a ceramic multilayer wiring board capable of reducing the impedance of a plane conductor by increasing the area of the plane conductor. It is to provide.

Means for solving the above problems (Means 1) has a structure in which a plurality of inner layer electrodes and a plurality of ceramic insulating layers are laminated to form a multilayer, and the plurality of inner layer electrodes are formed of the plurality of ceramic insulating layers. A method of manufacturing a ceramic multilayer wiring board connected to each other by a plurality of via conductors formed in a layer, the sheet preparing step of preparing a ceramic green sheet formed into a sheet shape having a main surface using a ceramic material; The unfired conductor layer forming step of forming a photosensitive unfired conductor layer on the main surface of the ceramic green sheet, and after the unfired conductor layer forming step, the unfired conductor layer is exposed and then developed. Accordingly, the plurality of island-shaped conductors connected to the plurality of via conductors, the plain-shaped conductor surrounding the plurality of island-shaped conductors, and the adjacent island-shaped conductors are extended. An exposure development process for forming a bridge portion that forms part of the plain conductor on the unfired conductor layer, and after the exposure development process, the ceramic green sheet and the unfired conductor layer are heated to a temperature of 1000 ° C. or higher. by co-firing in the ceramic green sheet and the ceramic insulating layer, seen including a firing step to the inner electrode of the unfired conductor layer, the thermal expansion coefficient difference between the inner electrode with respect to the ceramic insulating layer There is a method for manufacturing a ceramic multilayer wiring board, wherein the difference in thermal expansion coefficient of the unfired conductor layer with respect to the ceramic insulating layer is smaller .

  Therefore, according to the manufacturing method of the ceramic multilayer wiring board of means 1, the island-like conductor and the plain-like conductor are not formed by printing, but are formed by developing after exposing the unfired conductor layer. In this case, since printing blur does not occur, even if the gap between the island-shaped conductor and the plain-shaped conductor is reduced, the short-circuit between the two is prevented, so that the plain-shaped conductor can be spread toward the island-shaped conductor. In addition, in the exposure and development process, a bridge portion that extends between adjacent island-shaped conductors and forms a part of the plain-shaped conductor is formed, so that the island-shaped conductors are individually surrounded by the plain-shaped conductor including the bridge portion. be able to. As a result, the plain conductor is expanded by the area of the bridge portion. From the above, since the area of the plain conductor is increased, the impedance of the plain conductor can be reduced.

  Hereinafter, the manufacturing method of the ceramic multilayer wiring board according to the above means 1 will be described.

  In the sheet preparation step, a ceramic green sheet formed in a sheet shape having a main surface is prepared using a ceramic material. Here, preferable examples of the ceramic material include alumina, aluminum nitride, silicon nitride, boron nitride, beryllia, mullite, glass ceramic, and the like.

  In the subsequent unfired conductor layer forming step, an unfired conductor layer having photosensitivity is formed on the main surface of the ceramic green sheet. In the green conductor layer forming step, the green conductor layer may be formed by applying a photosensitive metallized paste mainly composed of tungsten or molybdenum on the main surface of the ceramic green sheet. In this way, the manufacturing cost of the ceramic multilayer wiring board can be reduced compared to the case of using a metallized paste mainly composed of gold or silver. The “main component” means that the photosensitive metallized paste contains 50% by volume or more of tungsten or molybdenum.

  Furthermore, the photosensitive metallized paste may contain metal particles having a particle size of 1 μm or more and 10 μm or less. If the particle size of the metal particles is less than 1 μm, that is, if the metal particles are nanoparticles, it is necessary to use metal particles different from general metal particles. The manufacturing cost will increase. On the other hand, when the particle size of the metal particles is larger than 10 μm, the unfired conductor layer formed by application of the photosensitive metallized paste becomes thick.

  In the exposure and development step after the unfired conductor layer forming step, the unfired conductor layer is exposed and developed to surround the multiple island-shaped conductors connected to the multiple via conductors and the multiple island-shaped conductors. A plain conductor and a bridge portion extending between adjacent island conductors and constituting a part of the plain conductor are formed in the unfired conductor layer. Note that the plain-shaped conductor including the bridge portion preferably constitutes a power supply conductor or a ground conductor. In such a case, since the problem peculiar to the present application that the impedance of the plain conductor is increased is likely to occur, the significance of adopting the means 1 is increased.

  In the firing step after the exposure and development step, the ceramic green sheet and the unfired conductor layer are simultaneously fired at a temperature of 1000 ° C. or higher, whereby the ceramic green sheet is used as the ceramic insulating layer and the unfired conductor layer is used as the inner layer electrode. A ceramic multilayer wiring board is manufactured through the above processes.

The thermal expansion coefficient difference of the inner electrode to the ceramic insulating layer, a that smaller than the thermal expansion coefficient difference unfired conductor layer to the ceramic insulating layer. In this case , the thermal stress due to the difference in thermal expansion coefficient between the ceramic insulating layer and the inner layer electrode is reduced, and the inner layer electrode is difficult to peel from the ceramic insulating layer, so that the yield is increased and the reliability is improved. Here, “thermal expansion coefficient” means the thermal expansion coefficient in the direction (XY direction) perpendicular to the thickness direction (Z direction), and the ceramic when the temperature is raised from 0 ° C. to 600 ° C. A value obtained by converting the amount of expansion of the insulating layer or inner layer electrode into the amount of expansion per unit temperature (thermal expansion coefficient = 0.degree. Of expansion of ceramic insulating layer when heated from 0.degree. C. to 600.degree. C./600.degree. C.).

Sectional drawing which shows the ceramic multilayer wiring board in this embodiment. The top view which shows an island-like conductor, a plain-like conductor, and a bridge | bridging part. The elements on larger scale of FIG. Sectional drawing which shows a sheet | seat preparation process. Sectional drawing which shows the process of forming a via conductor. Sectional drawing which shows an unbaking conductor layer formation process. Sectional drawing which shows an exposure development process. Sectional drawing which shows the process of forming a ceramic laminated body. The top view which shows an island-like conductor and a plain-like conductor in a prior art.

  Hereinafter, an embodiment in which the present invention is embodied in a ceramic multilayer wiring board will be described in detail with reference to the drawings.

  As shown in FIG. 1, the ceramic multilayer wiring board 10 of this embodiment is a component used in a part of an inspection apparatus for performing an electrical inspection of an IC chip (electronic component). The ceramic multilayer wiring board 10 is a wiring board having a length and width of about 10 cm and a thickness of about 4 mm. When used, the main surface 11 of the ceramic multilayer wiring board 10 is arranged toward the IC chip to be inspected. The

  Furthermore, a plurality of main surface side terminals 28 are formed in an array at the central portion on the main surface 11 of the ceramic multilayer wiring board 10. Each main surface side terminal 28 has a circular cross-section and a diameter of 50 μm. On the other hand, on the back surface 12 of the ceramic multilayer wiring substrate 10, a plurality of back surface side terminals 38 are formed in an array over almost the entire area. Each back terminal 38 has a circular cross-section and a diameter of 1.0 mm.

  As shown in FIG. 1, the ceramic multilayer wiring board 10 has a multilayered structure in which two layers of inner layer electrodes 41, 42 and three layers of ceramic insulating layers 31, 32, 33 are alternately stacked. Yes. The ceramic insulating layers 31 to 33 of the present embodiment are alumina sintered bodies, and the thermal expansion coefficient is set to 7.6 ppm / ° C. Further, the inner layer electrodes 41 and 42 of the present embodiment are metallized layers made of tungsten, and the thermal expansion coefficient is set to 4.5 ppm / ° C. Therefore, the difference in thermal expansion coefficient between the inner layer electrodes 41 and 42 with respect to the ceramic insulating layers 31 to 33 is 3.1 ppm / ° C. The thermal expansion coefficients of the inner layer electrodes 41 and 42 are values obtained by converting the expansion amount when the temperature is raised from 0 ° C. to 600 ° C. into the expansion amount per unit temperature (thermal expansion coefficient = 0 ° C. to 600 ° C. The amount of expansion of the inner layer electrodes 41 and 42/600 ° C.).

  A through hole 36 penetrating in the thickness direction is formed in each ceramic insulating layer 31 to 33, and a via conductor 37 connected to the inner layer electrodes 41 and 42 is formed in the through hole 36. Therefore, the inner layer electrodes 41 and 42 are connected to each other by the plurality of via conductors 37. Each through hole 36 has a circular cross-section and an inner diameter of 20 to 500 μm. Each via conductor 37 has a circular cross section and has an outer diameter of 20 to 500 μm. The via conductor 37 is a metallized layer made of the same material as the inner layer electrodes 41, 42, that is, tungsten.

  As shown in FIGS. 1 to 3, the first-layer inner layer electrode 41 includes an island-shaped conductor 51 and a plane-shaped conductor 52 including a bridge portion 53. A plurality of island conductors 51 are provided on the main surface 34 of the first ceramic insulating layer 31. Each island-like conductor 51 has a circular shape in plan view, and has a diameter A1 (see FIG. 3) set to 50 μm and a thickness of 10 μm. That is, the diameter A1 of the island-shaped conductor 51 is larger than the outer diameter (20 to 500 μm) of the via conductor 37. Each island-shaped conductor 51 is connected to an inner layer electrode 42 provided on the main surface of the ceramic insulating layer 32 through a via conductor 37 that penetrates the second ceramic insulating layer 32. Each island-shaped conductor 51 is connected to a back-side terminal formed on the back surface of the ceramic insulating layer 33 (the back surface 12 of the ceramic multilayer wiring board 10) via a via conductor 37 penetrating the first ceramic insulating layer 31. 38. Each island-shaped conductor 51 constitutes a signal conductor. Further, some of the island-shaped conductors 51 are connected to each other via a wiring pattern 54 (see FIG. 2) formed on the main surface 34 of the ceramic insulating layer 31.

  As shown in FIGS. 2 and 3, the plain-shaped conductor 52 covers substantially the entire area of the main surface 34 of the ceramic insulating layer 31, and individually surrounds the plurality of island-shaped conductors 51. Further, the bridge portion 53 extends between the adjacent island-shaped conductors 51 and constitutes a part of the plain-shaped conductor 52. In this embodiment, the thickness of the plane conductor 52 (and the bridge portion 53) is set to 10 μm, and the gap S1 (see FIG. 3) between the plane conductor 52 (and the bridge portion 53) and the island-shaped conductor 51 is 20 μm. Is set to The plain conductor 52 including the bridge portion 53 constitutes a power supply conductor or a ground conductor.

  Next, a method for manufacturing the ceramic multilayer wiring board 10 will be described.

  First, a sheet preparation process is performed, and ceramic green sheets 61, 62, and 63 having a thickness of 30 to 1000 μm are formed using a ceramic material mainly composed of alumina powder (see FIG. 4). In addition, each ceramic green sheet 61-63 is shape | molded by the sheet form which has the main surface 64 and the back surface 65 located in the other side of the main surface 64. FIG. And each ceramic green sheet 61-63 is drilled by laser processing, punching processing, drill processing, etc., and many 20-500 micrometers through-holes 36 are formed in a predetermined position (refer FIG. 4). Thereafter, using a conventionally known paste printing apparatus (not shown), each through hole 36 is filled with a conductive paste (tungsten paste in this embodiment) to form an unfired via conductor 39 (see FIG. 5). .

  In the subsequent unfired conductor layer forming step, a photosensitive metallized paste mainly composed of tungsten is applied (printed) onto the main surface 64 and the back surface 65 of each ceramic green sheet 61 using a paste printing apparatus. Further, a photosensitive metallized paste is applied (printed) onto the main surface 64 of the ceramic green sheets 62 and 63 using a paste printing apparatus. As a result, the unfired conductor layer 45 having a thickness of 10 μm is formed on the main surface 64 and the back surface 65 of the ceramic green sheet 61 and on the main surface 64 of the ceramic green sheets 62 and 63 ( (See FIG. 6). The photosensitive metallized paste of the present embodiment contains metal particles having a particle size of 1 μm or more and 10 μm or less (in this embodiment, tungsten metal particles). Further, the unfired conductor layer 45 of the present embodiment has a thermal expansion coefficient set to 3.5 ppm / ° C. Therefore, the difference in thermal expansion coefficient of the unfired conductor layer 45 with respect to the ceramic insulating layers 31 to 33 (thermal expansion coefficient is 7.6 ppm / ° C.) is 4.1 ppm / ° C. Therefore, the difference in thermal expansion coefficient (3.1 ppm / ° C.) of the inner layer electrodes 41 and 42 with respect to the ceramic insulating layers 31 to 33 is smaller than the difference in thermal expansion coefficient of the unfired conductor layer 45 with respect to the ceramic insulating layers 31 to 33. Become. The thermal expansion coefficient of the unfired conductor layer 45 is a value obtained by converting the expansion amount when the temperature is raised from 0 ° C. to 600 ° C. into the expansion amount per unit temperature (thermal expansion coefficient = 0 ° C. to 600 ° C. The amount of expansion of the unsintered conductor layer 45/600 ° C.).

  In the exposure development step after the unfired conductor layer forming step, the unfired conductor layer 45 is exposed and then developed. Specifically, first, based on CAD data, a direct drawing exposure apparatus (LDI: Laser Direct) is applied to the main surface 64 and the back surface 65 of the ceramic green sheet 61 and the main surface 64 of the ceramic green sheets 62 and 63. Imager) is irradiated with ultraviolet light to expose the unfired conductor layer 45. In addition, you may expose the unbaking conductor layer 45 using the method different from this embodiment. For example, a photomask including a plurality of light transmitting portions that can transmit ultraviolet light and a non-transmitting portion that cannot transmit ultraviolet light is disposed on the unfired conductor layer 45. Then, the unfired conductor layer 45 may be exposed by irradiating with ultraviolet light through a photomask from a conventionally known exposure machine (not shown).

  Thereafter, the exposed unfired conductor layer 45 is developed. As a result, the unfired conductor layer 45 formed on the main surface 64 of the ceramic green sheet 61 has an inner layer electrode 41 (island conductor 51, plain conductor 52, and bridge portion 53) in a region irradiated with ultraviolet light. Is formed (see FIG. 7). Further, in the unfired conductor layer 45 formed on the back surface 65 of the ceramic green sheet 61, a back surface side terminal 38 is formed in a region irradiated with ultraviolet light (see FIG. 7). Further, the unfired conductor layer 45 formed on the main surface 64 of the ceramic green sheet 62 is formed with an inner layer electrode 42 in a region irradiated with ultraviolet light (see FIG. 7). Further, in the unfired conductor layer 45 formed on the main surface 64 of the ceramic green sheet 63, the main surface side terminal 28 is formed in a region irradiated with ultraviolet light (see FIG. 7). That is, the unfired conductor layer 45 of this embodiment has negative photosensitivity in which a portion exposed during development is cured.

  Then, after drying the conductive paste and the photosensitive metallized paste, the ceramic green sheets 61 to 63 are stacked, and a pressing force is applied in the sheet stacking direction. As a result, the ceramic green sheets 61 to 63 are integrated to form a ceramic laminate 66 (see FIG. 8).

  In the firing step after the exposure and development step, the ceramic laminate 66 (ceramic green sheets 61 to 63, the unfired via conductor 39 and the unfired conductor layer 45) is degreased and further heated to a temperature of 1000 ° C. or higher (eg, 1400 ° C. to 1600 ° C.). At the same temperature). As a result, alumina in the ceramic green sheets 61 to 63, tungsten in the conductive paste, and tungsten in the photosensitive metallized paste are simultaneously sintered, and the ceramic green sheets 61 to 63 become the ceramic insulating layers 31 to 33. The unfired via conductor 39 becomes the via conductor 37, and the unfired conductor layer 45 becomes the inner layer electrodes 41 and 42. In the present embodiment, the difference between the sintering temperature of the ceramic green sheets 61 to 63 and the sintering temperature of the green conductor layer 45 (and the green via conductor 39) is 100 ° C. or less. The ceramic multilayer wiring board 10 is manufactured through the above processes.

  Therefore, according to the present embodiment, the following effects can be obtained.

  (1) According to the method for manufacturing the ceramic multilayer wiring board 10 of the present embodiment, the island-shaped conductor 51 and the plane-shaped conductor 52 are not formed by printing as in the prior art, but the unfired conductor layer 45 is exposed. Then, it is formed by developing. In this case, since printing blur does not occur, even if the gap S1 between the island-shaped conductor 51 and the plane-shaped conductor 52 is reduced, a short circuit between the two is prevented, so that the plane-shaped conductor 52 is moved to the island-shaped conductor 51 side. Can be spread. In addition, in the exposure and development process, since the bridge portion 53 that extends between the adjacent island conductors 51 and constitutes a part of the plane conductor 52 is formed, the island conductor 51 is formed into a plain shape including the bridge portion 53. The conductors 52 can be individually surrounded. As a result, the plane conductor 52 is expanded by the area of the bridge portion 53. From the above, since the area of the plane conductor 52 is increased, the impedance of the plane conductor 52 can be reduced.

  (2) By the way, it is conceivable to form island-like conductors 51, plain-like conductors 52, and the like by spraying a photosensitive metallized paste using an inkjet device. However, in this case, there is a problem that the photosensitive metallized paste cannot be ejected unless metal particles (specifically, nanoparticles) having a particle diameter of less than 1 μm are used as the metal particles contained in the photosensitive metallized paste. . However, even if the nanoparticles are used as the metal particles, the temperature at which the photosensitive metallized paste starts firing shrinkage does not match the temperature at which the ceramic green sheets 61-63 start firing shrinkage. There is a risk of delamination.

  Therefore, in this embodiment, the photosensitive metallized paste containing metal particles having a particle diameter of 1 μm or more is applied using a paste printing apparatus, and then exposed and developed, whereby the island-shaped conductor 51 and the plain shape are formed. A conductor 52 and the like are formed. In this case, since the timing at which the photosensitive metallized paste is fired and contracted coincides with the timing at which the ceramic green sheets 61 to 63 are fired and contracted, the above problems (warping, surface irregularities, and delamination) are prevented.

  (3) It is also conceivable to form island-like conductors 51, plain-like conductors 52, etc. by screen printing. However, in this case, there is a problem that the conductors 51 and 52 are thick at the outer peripheral portions of the conductors 51 and 52, whereas the conductors 51 and 52 are thin at the central portion of the conductors 51 and 52.

  On the other hand, in this embodiment, the photosensitive metallized paste is applied using a paste printing apparatus, and then exposed and developed to form island-like conductors 51, plain-like conductors 52, and the like. In this case, the thickness of the conductors 51 and 52 is constant both in the outer peripheral portion and in the central portion, so that the electric resistance value becomes uniform and electricity flows stably. Furthermore, when obtaining the same electric resistance value as in the case of screen printing, the conductors 51 and 52 can be made to have the same thickness (that is, thinner) as the portion that becomes thinner in the case of screen printing. In this case, it is easy to prevent delamination between the conductors 51 and 52 and the ceramic insulating layer 31 starting from the outer peripheral edges of the conductors 51 and 52.

  In addition, you may change this embodiment as follows.

  In the above embodiment, the plane conductor 52 including the bridge portion 53 constitutes a power supply conductor or a ground conductor, but may constitute a signal conductor.

  The unfired conductor layer 45 of the above embodiment has a negative photosensitivity in which a portion exposed during development is cured, but the unfired conductor layer 45 is a positive type in which a portion exposed during development is dissolved. The photosensitivity may be as follows.

  -In the unbaked conductor layer formation process of the said embodiment, the photosensitive metallizing paste was apply | coated (printed) using the paste printing apparatus. However, a metal mask is disposed on the main surface 64 and the back surface 65 of the ceramic green sheet 61 and the main surface 64 of the ceramic green sheets 62 and 63, and in the unfired conductor layer forming step, the photosensitive material is exposed via the metal mask. A metallic metallized paste may be applied.

  Next, in addition to the technical ideas described in the claims, the technical ideas grasped by the embodiment described above are listed below.

  (1) A method for producing a ceramic multilayer wiring board according to the above means 1, wherein the unsintered conductor layer has negative photosensitivity in which a portion exposed during development is cured.

  (2) The method for manufacturing a ceramic multilayer wiring board according to the above means 1, wherein the unsintered conductor layer has positive photosensitivity in which a portion exposed during development is dissolved.

  (3) In the above means 1, in the unfired conductor layer forming step, a photosensitive metallized paste mainly composed of tungsten or molybdenum is applied on the main surface of the ceramic green sheet through a metal mask, A method for producing a ceramic multilayer wiring board, comprising forming the green conductor layer.

  (4) In the said means 1, in the said exposure and development process, the said unbaking conductor layer is exposed through a photomask, The manufacturing method of the ceramic multilayer wiring board characterized by the above-mentioned.

  (5) In the said means 1, the manufacturing method of the ceramic multilayer wiring board characterized by the clearance gap between the said island-shaped conductor and the said plane-shaped conductor being 50 micrometers or less.

  (6) The method for producing a ceramic multilayer wiring board according to the above means 1, wherein the difference between the sintering temperature of the ceramic green sheet and the sintering temperature of the unfired conductor layer is 100 ° C. or less.

  (7) The method for manufacturing a ceramic multilayer wiring board according to the above means 1, wherein the thickness of the unfired conductor layer is 30 μm or less.

DESCRIPTION OF SYMBOLS 10 ... Ceramic multilayer wiring board 31, 32, 33 ... Ceramic insulating layer 37 ... Via conductor 41, 42 ... Inner layer electrode 45 ... Unsintered conductor layer 51 ... Island-like conductor 52 ... Planar conductor 53 ... Bridge part 61, 62, 63 ... Ceramic green sheet 64 ... Main surface of ceramic green sheet

Claims (4)

A ceramic having a multilayer structure in which a plurality of inner layer electrodes and a plurality of ceramic insulating layers are stacked, and the plurality of inner layer electrodes are connected to each other by a plurality of via conductors formed in the plurality of ceramic insulating layers A method for manufacturing a multilayer wiring board, comprising:
A sheet preparation step of preparing a ceramic green sheet formed into a sheet shape having a main surface using a ceramic material;
An unfired conductor layer forming step of forming an unfired conductor layer having photosensitivity on the main surface of the ceramic green sheet;
After the unfired conductor layer forming step, the unfired conductor layer is exposed and developed to develop a plurality of island-shaped conductors connected to the plurality of via conductors, and a plain shape surrounding the plurality of island-shaped conductors An exposure and development step of forming a conductor and a bridge portion extending between adjacent island-shaped conductors and forming a part of the plain-shaped conductor in the unfired conductor layer;
After the exposure and development step, the ceramic green sheet and the unfired conductor layer are simultaneously fired at a temperature of 1000 ° C. or more, whereby the ceramic green sheet is used as the ceramic insulating layer, and the unfired conductor layer is used as the inner electrode. and the firing step seen including that,
The method for manufacturing a ceramic multilayer wiring board , wherein a difference in thermal expansion coefficient of the inner layer electrode with respect to the ceramic insulating layer is smaller than a difference in thermal expansion coefficient of the unfired conductor layer with respect to the ceramic insulating layer .   2. The method for manufacturing a ceramic multilayer wiring board according to claim 1, wherein the plain-shaped conductor including the bridge portion constitutes a power supply conductor or a ground conductor. In the unfired conductor layer forming step, the unfired conductor layer is formed by applying a photosensitive metallized paste mainly composed of tungsten or molybdenum on the main surface of the ceramic green sheet. Item 3. A method for producing a ceramic multilayer wiring board according to Item 1 or 2 . 4. The method for producing a ceramic multilayer wiring board according to claim 3 , wherein the photosensitive metallized paste contains metal particles having a particle size of 1 [mu] m to 10 [mu] m.

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