Ceramic wiring member

Abstract

This ceramic wiring member (1) comprises: a body portion (10) made of ceramic and having tabular portions (11, 12); and an electrically conductive portion (20) disposed in contact with the tabular portions (11, 12). The composition of the electrically conductive portion (20) includes: an electrically conductive phase (31) that comprises at least one metal component of W or Mo and has a plurality of pores (31A) dispersed spaced apart from one another; and glass phases (32) that fill the plurality of pores (31A) and occupy 3-20% inclusive of the area in a cross-section in the thickness direction of the tabular portions (11, 12). In the cross-section in the thickness direction of the tabular portions (11, 12), the number of glass phases (32) that have an aspect ratio of 1.5 or less constitute 40% or more of the total number of glass phases (32).

Description

Technical Field

[0001] The present disclosure relates to a ceramic wiring member.

Background Art

[0002] A ceramic wiring member including a ceramic main body having a plate-like portion and a conductive portion composed of a material containing a metal disposed in contact with the plate-like portion is known. Such a ceramic wiring member is used as a member for holding an electronic component. The conductive portion constitutes part of a current path to or from the electronic component. In such a ceramic wiring member, it is important to reduce the electrical resistance of the conductive portion. On the other hand, due to the difference in the coefficient of linear expansion between the ceramic constituting the main body portion and the metal constituting the conductive portion, the ceramic wiring substrate may be warped. If this warpage becomes large, there is a risk of problems such as the conductive portion peeling off from the main body portion. Therefore, reduction of warpage is desired.

[0003] For example, by introducing a ceramic glass phase into the conductive portion to bring the coefficient of linear expansion of the conductive portion close to that of the main body portion, the above warpage can be reduced. Among the ceramics constituting the main body portion, it is known that a glass phase mainly composed of a component added as a sintering aid is formed in the conductive portion in the manufacturing process of the ceramic wiring member (see, for example, Japanese Patent Application Laid-Open No. 2003-347710 (Patent Document 1)). Although the formation of the glass phase increases the electrical resistance of the conductive portion, it is considered that by forming an appropriate amount of the glass phase, the warpage can be reduced while allowing the increase in electrical resistance within an acceptable range.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, even when the ratio of the glass phase in the conductive portion is within an appropriate range as described above, there are cases where the electrical resistance rises beyond the allowable range or the warpage cannot be sufficiently reduced.

[0006] One of the objects of the present disclosure is to provide a ceramic wiring member capable of achieving both reduction of warpage and reduction of the electrical resistance of the conductive portion.

Means for Solving the Problems

[0007] The ceramic wiring member according to the present disclosure includes a ceramic main body portion having a plate-shaped portion and a conductive portion disposed in contact with the plate-shaped portion. The structure of the conductive portion is composed of a metal component containing at least one of W (tungsten) and Mo (molybdenum), and includes a conductive phase having a plurality of voids dispersed apart from each other, and a glass phase that fills the plurality of voids and has an area ratio in the cross-section in the thickness direction of the plate-shaped portion of 3% or more and 20% or less. In the cross-section in the thickness direction of the plate-shaped portion, the ratio of the number of glass phases having an aspect ratio of 1.5 or less among all the glass phases is 40% or more.

Effects of the Invention

[0008] According to the above ceramic wiring member, it is possible to provide a ceramic wiring member capable of achieving both reduction of warpage and reduction of the electrical resistance of the conductive portion.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

DETAILED DESCRIPTION OF THE INVENTION

[0010] [Overview of Embodiment] First, embodiments of the present disclosure will be listed and described. The ceramic wiring member in the first aspect of the present disclosure includes a ceramic main body portion having a plate-like portion and a conductive portion disposed in contact with the plate-like portion. The structure of the conductive portion is composed of a metal component containing at least one of W and Mo, and has a conductive phase in which a plurality of voids are dispersed apart from each other, and a glass phase that fills the plurality of voids and has an area ratio of 3% or more and 20% or less in the cross-section in the thickness direction of the plate-like portion. In the cross-section in the thickness direction of the plate-like portion, the ratio of the number of glass phases having an aspect ratio of 1.5 or less to the total number of glass phases is 40% or more.

[0011] In the ceramic wiring member of the first aspect, in the cross-section in the thickness direction of the plate-like portion, the ratio of the number of glass phases having an aspect ratio of 2 or less to the total number of glass phases may be 65% or more.

[0012] The inventor has studied the reasons why the electrical resistance increases beyond the allowable range or the warpage cannot be sufficiently reduced even when the ratio of the glass phase in the conductive portion is within an appropriate range. As a result, the following findings were obtained.

[0013] Regarding the values of the electrical resistance and warpage, the shape of the glass phase that fills the voids has an impact. Specifically, when the shape of each glass phase is far from spherical, that is, when the aspect ratio of the glass phase is large in the cross-section in the thickness direction of the plate-like portion, the influence on the increase in the value of the electrical resistance and the value of warpage is significant. The reasons for this are considered as follows, for example. When the aspect ratio of the glass phase is large, stress concentration is likely to occur near the tip in the longitudinal direction of the glass phase. Therefore, when stress is applied to the conductive portion in the manufacturing process of the ceramic wiring member after firing the main body portion and the conductive portion, stress concentrates near the tip, and minute cracks occur in the conductive phase. The occurrence of these cracks increases the electrical resistance of the conductive portion. Also, when the aspect Ratio ratio of the glass phase is large, a difference in the amount of expansion occurs between the major axis direction and the minor axis direction. Then, the glass phase does not contract (or expand) isotropically in three dimensions. As a result, non-uniform stress is generated, and the value of warpage increases.

[0014] On the other hand, when the aspect ratio of the glass phase is close to 1, that is, when the shape of the glass phase is close to spherical, the influence of the presence of the glass phase on the increase in the value of the electrical resistance and the value of warpage is small. More specifically, in the cross-section in the thickness direction of the plate-like portion, the ratio of the number of glass phases with an aspect ratio of 1.5 or less among all the glass phases is 40% or more, preferably the ratio of the number of glass phases with an aspect ratio of 1.5 or less is 40% or more, and the ratio of the number of glass phases with an aspect ratio of 2 or less is 65% or more, whereby the influence of the presence of the glass phase on the increase in the value of the electrical resistance and the value of warpage is reduced. As a result, according to the ceramic wiring member of the present disclosure, it is possible to provide a ceramic wiring member capable of achieving both reduction of warpage and reduction of the electrical resistance of the conductive portion.

[0015] Here, in the present application, the aspect ratio of the glass phase means the ratio of the major axis to the minor axis in the ellipse with the smallest area containing each glass phase inside. This aspect ratio can be obtained, for example, for the conductive part, by observing the cross-section in the thickness direction of the plate-like part with a scanning electron microscope, binarizing the obtained image data into black and white with image processing software, determining the ellipse with the smallest area containing each glass phase inside, and calculating the ratio of the major axis to the minor axis (major axis / minor axis) of the ellipse. The data is acquired such that 150 or more glass phases are included in the image data. Further, in the present application, the glass phase may contain, in addition to the glass components contained in the main body part, crystals of the main ceramic component (alumina) contained in the main body part and a small amount of metal components in the conductive part. Also, the glass phase may contain glass components not contained in the main body part.

[0016] In the above ceramic wiring member, the conductive part may include a first part that contacts the first main surface of the plate-like part and a second part that contacts the second main surface located on the side opposite to the first main surface in the thickness direction of the plate-like part. In this way, by electrically connecting the first main surface side and the second main surface side of the plate-like part by the conductive part with reduced electrical resistance, a high-performance ceramic wiring member capable of coping with power saving and high-speed communication speed can be obtained.

[0017] [Specific Example of Embodiment] Next, a specific embodiment of the ceramic wiring member of the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals and their description will not be repeated.

[0018] (Embodiment 1) FIG. 1 is a schematic cross-sectional view showing the structure of a ceramic wiring member according to an embodiment of the present disclosure. Referring to FIG. 1, the ceramic wiring member 1 of the present embodiment includes a ceramic main body 10 and a conductive part 20. The ceramic constituting the main body 10 is not particularly limited, and for example, aluminum oxide (Al2O3) can be adopted. Further, the ceramic constituting the main body 10 may contain at least one glass component selected from the group consisting of oxides containing Si, oxides containing Ca, oxides containing Mg, oxides containing Mn, and oxides containing Ba as a sintering aid.

[0019] The main body 10 includes a bottom wall 11 as a first plate-shaped part having a plate shape and a side wall 12 as a second plate-shaped part having a plate shape. The bottom wall 11 has a flat plate shape. The bottom wall 11 includes a first main surface 11A and a second main surface 11B located on the opposite side of the first main surface 11A in the thickness direction. The planar shape of the bottom wall 11 (the shape seen in the direction perpendicular to the first main surface 11A) is, for example, rectangular.

[0020] The side wall 12 has a plate shape rising from the outer edge of the first main surface 11A of the bottom wall 11. More specifically, for example, it has a shape in which four flat plates corresponding to the respective sides of the outer edge of the first main surface 11A of the bottom wall 11 having a rectangular planar shape are connected to each other. When viewed in the direction perpendicular to the first main surface 11A, the side wall 12 may be arranged so as to surround, for example, a cavity 10A which is a space on the first main surface 11A. The side wall 12 includes a planar first end surface 12A and a second end surface 12B which is a planar end surface on the opposite side of the first end surface 12A in the thickness direction of the bottom wall 11. The side wall 12 is connected to the first main surface 11A of the bottom wall 11 at the second end surface 12B. The first end surface 12A is located on a single plane throughout the entire area. As a result, by placing a flat lid member on the first end surface 12A, the cavity 10A can be closed. Electronic components such as crystal oscillators that require airtightness can be housed in the cavity 10A. Such a ceramic wiring member 1 is used as a ceramic package.

[0021] In the present embodiment, the ceramic wiring member 1 includes a pair of conductive portions 20. Each conductive portion 20 includes an internal terminal 21 as a first portion arranged in contact with the first main surface 11A, an external terminal 25 as a second portion arranged in contact with the second main surface 11B, and an internal wiring 23 arranged inside the bottom wall portion 11. Each conductive portion 20 further includes a first connection portion 22 connecting the internal terminal 21 and the internal wiring 23, and a second connection portion 24 connecting the internal wiring 23 and the external terminal 25. The internal wiring 23, the first connection portion 22, and the second connection portion 24 are a third portion connecting the internal terminal 21 as a first portion and the external terminal 25 as a second portion. The internal terminal 21, the external terminal 25, the internal wiring 23, the first connection portion 22, and the second connection portion 24 are all part of the conductive portion 20 arranged in contact with the bottom wall portion 11 as the first plate-like portion. Note that, as a modification example of the first connection portion 22 and the second connection portion 24, for example, a castellation may be provided on the side surface of the bottom wall portion 11, and a conductive portion may be provided on the castellation surface.

[0022] Referring to FIG. 2, at least one, preferably all of the internal terminal 21, the external terminal 25, the internal wiring 23, the first connection portion 22, and the second connection portion 24 constituting the conductive portion 20 are made of a metal component containing at least one of W and Mo, and have a conductive phase 31 having a plurality of voids 31A dispersed away from each other, and a glass phase 32 filling the plurality of voids 31A and having an area ratio of 3% or more and 20% or less in the cross-sectional area in the thickness direction of the bottom wall portion 11. The glass phase 32 having an area ratio of 20% or less suppresses an increase in the electrical resistance of the conductive portion 20, and the glass phase 32The area ratio of is 3% or more, preferably 8% or more, whereby the difference in the linear expansion coefficients between the conductive part 20 and the main body part 10 can be reduced. The glass phase 32 in the conductive part 20 basically penetrates by capillary action from the main body part during sintering, but the glass phase 32 may contain a glass component not contained in the main body part 10. From the viewpoints of electrical resistance and strength, the void 31A not filled with the glass phase 32 is desirably 5% or less, and more desirably 1% or less, in terms of the area ratio in the cross-section of the conductive part 20. In the cross-section in the thickness direction of the bottom wall part 11 (the cross-section shown in FIG. 2), the ratio of the number of glass phases 32 having an aspect ratio of 1.5 or less among all the glass phases 32 is 40% or more. Regarding the glass phase 32, it is desirable that the major axis of the ellipse obtained by the elliptical fitting described later is 0.1 μm or more and 4 μm or less. By setting the major axis of the ellipse to 0.1 μm or more, the void 31A in the conductive part 20 is suppressed, and the strength of the conductive part 20 increases. Also, by setting the major axis of the ellipse to 4 μm or less, the electrical resistance of the conductive part 20 can be reduced.

[0023] In the ceramic wiring member 1 of the present embodiment, in the cross-section in the thickness direction of the bottom wall part 11 as the plate-like part, the ratio of the number of glass phases 32 having an aspect ratio of 1.5 or less among all the glass phases 32 is 40% or more. Thereby, the influence of the presence of the glass phase 32 on the increase in the value of the electrical resistance and the value of warpage of the conductive part 20 is reduced. As a result, the ceramic wiring member 1 of the present embodiment is a ceramic wiring member in which both warpage reduction and reduction of the electrical resistance of the conductive part 20 are achieved.

[0024] In the ceramic wiring member 1 of the above-described present embodiment, it is preferable that the ratio of the number of glass phases having an aspect ratio of 2 or less among all the glass phases 32 is 65% or more. Thereby, the influence of the presence of the glass phase 32 on the increase in the value of the electrical resistance and the value of warpage of the conductive part 20 is more surely reduced. As a result, the ceramic wiring member 1 of the present embodiment can be made into a ceramic wiring member in which both warpage reduction and reduction of the electrical resistance of the conductive part 20 are more surely achieved.

[0025] Next, an example of the manufacturing method of the ceramic wiring member 1 in the present embodiment will be described. FIG. 3 is a flowchart showing an outline of the manufacturing method of the ceramic wiring member. Referring to FIG. 3, in the manufacturing method of the ceramic wiring member 1 of the present embodiment, first, as step S10, a green sheet preparation step is carried out. In this step S10, a green sheet to be the main body portion 10 is prepared. Specifically, Al2O3, which is the main component of the ceramic powder constituting the main body portion 10, a sintering aid powder, and further a resin, a solvent, etc. that do not constitute the main body portion 10 (i.e., disappear during firing) are mixed in a ball mill to obtain a slurry. This slurry is processed into a green sheet by the doctor blade method. Thereby, a green sheet to be the main body portion 10 is obtained. Here, referring to FIG. 1, a plurality of green sheets having a rectangular planar shape are prepared as the green sheets to be the bottom wall portion 11. Also, a plurality of green sheets to be the side wall portion 12 are prepared. As the green sheets to be the side wall portion 12, annular green sheets having a rectangular planar shape and with the portion (central portion) corresponding to the cavity 10A removed are prepared.

[0026] Next, as step S20, a conductive portion printing step is carried out. In this step S20, a paste to be the conductive portion 20 is printed on the green sheet prepared in step S10. Specifically, first, at least one first metal component of W and Mo, at least one second metal component selected from the group consisting of Ni, Co, and Fe, an additive, a resin, a solvent, etc. are blended, and further, ceramic powder is added as necessary and kneaded to create a paste. The ceramic powder may be the same as or different from that constituting the main body portion 10.

[0027] Print this paste on the green sheet prepared in step S10, for example, by screen printing. As a result, referring to FIG. 1, as the green sheet to become the bottom wall portion 11, a green sheet with the paste printed in the area corresponding to the external terminal 25, a green sheet with the paste printed in the area corresponding to the second connection portion 24, a green sheet with the paste printed in the area corresponding to the internal wiring 23, a green sheet with the paste printed in the area corresponding to the first connection portion 22, and a green sheet with the paste printed in the area corresponding to the internal terminal 21 are produced. After being dried, they are laminated in this order. Drying can be carried out, for example, under the condition of heating to 110° C. and holding for 5 minutes.

[0028] Furthermore, a plurality of additional green sheets (annular green sheets with the portion corresponding to the cavity 10A removed) to become the side wall portion 12 prepared in step S10 are laminated. In this way, a laminate of green sheets is obtained.

[0029] Next, as step S30, a firing process is carried out. In this process, the laminate of green sheets prepared in step S20 is fired. Firing can be carried out, for example, by heating to a temperature of 800° C. or higher and 1600° C. or lower in an atmosphere in which hydrogen, nitrogen, and water vapor are mixed. The heating temperature is selected from the temperature range that can suppress the formation of an intermetallic compound phase composed of an intermetallic compound of the first metal component and the second metal component in the structure of the conductive portion 20, taking into account the sufficient progress of sintering. By the above procedure, the ceramic wiring member 1 of the present embodiment can be manufactured.

[0030] In the method for manufacturing the ceramic wiring member 1 of the present embodiment, in step S20, as the metal component constituting the conductive phase 31, in addition to the first metal component, a second metal component is adopted. The second metal component is added in a proportion of 0.1% or more and 10% or less with respect to the first metal component. The remainder of the metal components other than the first metal component and the second metal component is only inevitable impurities. By adding the second metal component, in step S30, it is possible to suppress the intrusion of the glass phase containing the sintering aid constituting the main body portion 10 into the conductive portion 20. Further, by adding the second metal component, sintering of the metal powder, which is the raw material powder of the conductive portion 20, can be promoted. As a result, connection of the glass phases 32 filling the adjacent voids 31A is suppressed, and the aspect ratio of the glass phase 32 becomes small. The method for manufacturing the ceramic wiring member 1 of the present embodiment is not limited to the above manufacturing method, but the ceramic wiring member 1 of the present embodiment can be easily manufactured by the above manufacturing method.

[0031] (Embodiment 2) Next, Embodiment 2, which is another embodiment of the present disclosure, will be described. FIG. 4 is a schematic cross-sectional view showing the structure of the ceramic wiring member in Embodiment 2. FIG. 4 is a figure corresponding to FIG. 1 referred to in the description of Embodiment 1. Referring to FIGS. 4 and 1, the ceramic wiring member 1 of Embodiment 2 basically has the same configuration as that of Embodiment 1 and exhibits the same effects. However, the ceramic wiring member 1 of Embodiment 2 is mainly different from that of Embodiment 1 in the arrangement and structure of the conductive portion. Hereinafter, Embodiment 2 will be described centering on the differences from Embodiment 1.

[0032] Referring to FIG. 4, the conductive portion 20 of the ceramic wiring member 1 according to the second embodiment includes an upper terminal 26 as a first portion disposed in contact with the first end face 12A, a lower terminal 28 as a second portion disposed in contact with the second end face 12B, and a third connection portion 27 connecting the upper terminal 26 and the lower terminal 28. The lower terminal 28 is disposed so as to also contact the first main surface 11A of the bottom wall portion 11. The upper terminal 26, the lower terminal 28, and the third connection portion 27 are all part of the conductive portion 20 disposed in contact with the side wall portion 12 as the second plate-like portion.

[0033] At least one, preferably all, of the compositions of the upper terminal 26, the lower terminal 28, and the third connection portion 27 constituting the conductive portion 20 include a first metal component as a main component that is at least one of W and Mo, similar to the internal terminal 21 in the first embodiment, and at least one second metal component selected from the group consisting of Ni, Co, and Fe that is 0.1% or more and 10% or less in total with respect to the first metal component. Further, at least one, preferably all, of the structures of the upper terminal 26, the lower terminal 28, and the third connection portion 27 constituting the conductive portion 20 include a conductive phase composed of an alloy of the first metal component and the second metal component, similar to the internal terminal 21 in the first embodiment. Further, at least one, preferably all, of the structures of the upper terminal 26, the lower terminal 28, and the third connection portion 27 constituting the conductive portion 20 include a glass phase 32 composed of a ceramic component having an area ratio of 3% or more and 20% or less in the cross section of the conductive portion 20.

[0034] Also in the ceramic wiring member 1 of the present embodiment, the same effects as in the first embodiment can be obtained. Further, the ceramic wiring member 1 of the present embodiment can be manufactured in the same manner as in the first embodiment, except that the arrangement of the conductive portion 20 is mainly changed. In the present embodiment, the bottom wall portion 11 is made of ceramic, which is an insulator, but a conductor such as metal may be adopted as the material constituting the bottom wall portion 11.

[0035] (Embodiment 3) Next, Embodiment 3, which is yet another embodiment of the present disclosure, will be described. FIG. 5 is a schematic cross-sectional view showing the structure of the ceramic wiring member in Embodiment 3. FIG. 5 corresponds to FIG. 1 referred to in the description of Embodiment 1. Referring to FIGS. 5 and 1, the ceramic wiring member 1 of Embodiment 3 basically has the same configuration as that of Embodiment 1 and exhibits the same effects. However, the ceramic wiring member 1 of Embodiment 3 is different from that of Embodiment 1 mainly in the structure of the main body portion, the arrangement, and the structure of the conductive portion. Hereinafter, Embodiment 3 will be described centering on the differences from Embodiment 1.

[0036] Referring to FIG. 5, the side wall portion 12 of the ceramic wiring member 1 of Embodiment 3 includes a protruding portion 121 that protrudes toward the regions facing each other across the cavity 10A. The protruding portion 121 includes a first surface 121B facing the first main surface 11A of the bottom wall portion 11, a second surface 121A located on the side opposite to the first surface 121B in the thickness direction of the bottom wall portion 11, and a third surface 121C that is the tip surface connecting the first surface 121B and the second surface 121A. The region including the tip connected to the third surface 121C of the first surface 121B faces the first main surface 11A, and the other region (the region corresponding to the vicinity of the root of the protruding portion 121) does not face the first main surface 11A.

[0037] The conductive portion 20 includes an upper terminal 26 as a first portion arranged in contact with the first end surface 12A, a lower terminal 28 as a second portion arranged in contact with the second end surface 12B, and a third connection portion 27 connecting the upper terminal 26 and the lower terminal 28. The conductive portion 20 further includes an intermediate terminal 30 arranged in contact with the first surface 121B and a fourth connection portion 29 connecting the intermediate terminal 30 and the third connection portion 27. The intermediate terminal 30 is arranged so as to also contact the first main surface 11A of the bottom wall portion 11. The upper terminal 26, the lower terminal 28, the third connection portion 27, the intermediate terminal 30, and the fourth connection portion 29 are all parts of the conductive portion 20 arranged in contact with the side wall portion 12.

[0038] Among at least one, preferably all, of the upper terminal 26, the lower terminal 28, the third connection part 27, the intermediate terminal 30, and the fourth connection part 29 that constitute the conductive part 20, the composition of each is, similar to the internal terminal 21 etc. of Embodiment 1, a first metal component that is at least one of W and Mo as a main component, and at least one second metal component selected from the group consisting of Ni, Co, and Fe that is 0.1% or more and 10% or less in total with respect to the first metal component. Further, among the structures of the upper terminal 26, the lower terminal 28, and the third connection part 27 that constitute the conductive part 20, at least one, preferably all, of the structures include a conductive phase composed of an alloy of the first metal component and the second metal component, similar to the internal terminal 21 etc. of Embodiment 1. Here, the alloy refers to not only a solid solution composed of the first metal component and the second metal component but also a mixture of the first metal component and the second metal component that has not been solidified. Further, at least one, preferably all, of the structures of the upper terminal 26, the lower terminal 28, the third connection part 27, the intermediate terminal 30, and the fourth connection part 29 that constitute the conductive part 20 include a glass phase 32 composed of a ceramic component that has an area ratio of 3% or more and 20% or less in the cross-section of the conductive part 20.

[0039] Also in the ceramic wiring member 1 of the present embodiment, the same effects as in the case of Embodiment 1 can be obtained. Further, the ceramic wiring member 1 of the present embodiment can be manufactured in the same manner as in the case of Embodiment 1, except mainly for changing the structure of the main body part 10 and the arrangement of the conductive part 20. In the present embodiment, the bottom wall part 11 is made of ceramic which is an insulator, but a conductor such as metal may be adopted as the material constituting the bottom wall part 11. Also, in the above embodiment, the shape of the main body part 10 was exemplified, but the shape of the main body part of the present disclosure is not limited to these. As the shape of the main body part, various shapes such as a rectangular parallelepiped shape, a spherical shape, and a film shape can be adopted, for example.

Examples

[0040] An experiment was conducted to investigate the effects of the area ratio and aspect ratio of the glass phase on the resistivity of the conductive part, the warp of the ceramic wiring member, and the adhesion strength of the conductive part to the main body part. The procedure of the experiment is as follows.

[0041] A conductive part 20 arranged in contact with the main body part 10 was formed by the same procedure as the manufacturing method described in the above embodiment, and the resistivity of the conductive part 20, the warp of the ceramic wiring member 1, and the adhesion strength of the conductive part 20 to the main body part 10 were investigated. Specifically, in step S10, a green sheet containing Al2O3 powder, at least one powder selected from the group consisting of SiO2, CaO, MgO, MnO, and BaO as a sintering aid, resin, solvent, etc. was prepared.

[0042] Next, in step S20, a paste containing a first metal component was printed on the green sheet prepared in step S10 and dried. No ceramic component was added to the paste. Drying was carried out under the condition of heating to 110°C and holding for 5 minutes. At this time, at least one of W and Mo was adopted as the first metal component. Also, from the viewpoint of changing the area ratio and aspect ratio of the glass phase, the addition amounts of Ni, Co, and Fe as the second metal component were changed. Also, samples without adding the second metal component were prepared.

[0043] Then, in step S30, the green sheet printed with the paste was fired. Firing was carried out by heating from room temperature to a predetermined temperature in an atmosphere in which hydrogen, nitrogen, and water vapor were mixed, and then cooling to room temperature. As a result, a sample in which a conductive part was arranged on one main surface of a ceramic main body part having a plate-like part was obtained. In this sample, no conductive part or internal wiring was provided on the other main surface. Regarding the conductive part after firing, the voids not filled with the glass phase were 1% or less in area ratio.

[0044] Regarding the obtained samples, the area ratio of the glass phase in the conductive portion in the cross-section in the thickness direction of the plate-like portion, the ratio of the number of glass phases with an aspect ratio of 1.5 or less among the total number of glass phases, and the ratio of the number of glass phases with an aspect ratio of 2 or less were investigated. Specifically, regarding the obtained samples, the cross-section of the conductive portion 20 was observed with a scanning electron microscope. Then, regarding the obtained image data, after performing binary black-and-white conversion with image processing software, the areas of the glass phases 32 were totaled, and the area ratio of the glass phase 32 in the conductive portion 20 was calculated. In addition, an ellipse with the minimum area containing each glass phase was determined (ellipse fitting), and the aspect ratio of each glass phase was obtained by calculating the ratio of the major axis to the minor axis (major axis / minor axis) of the ellipse. Then, based on the aspect ratio of each obtained glass phase, the number of glass phases with an aspect ratio of 1.5 or less was calculated. Based on this result, the ratio of the number of glass phases with an aspect ratio of 1.5 or less to the total number of glass phases, and the ratio of the number of glass phases with an aspect ratio of 2 or less within the field of view observed with the scanning electron microscope were calculated. ImageJ (free software) was used for the above image processing.

[0045] Furthermore, regarding the obtained samples, the resistivity of the conductive portion 20 was investigated. Specifically, regarding the obtained samples, first, the electrical resistance of the conductive portion 20 was measured by the four-terminal method. For the measurement of the electrical resistance, RM3544-01 manufactured by Hioki Electric Co., Ltd. was used. Then, the resistivity was calculated from the obtained electrical resistance, the length of the conductive portion 20, and the cross-sectional area perpendicular to the longitudinal direction.

[0046] Also, regarding the obtained samples, the warp was measured. Specifically, using a three-dimensional shape measuring device (model number VK-X1000) manufactured by Keyence Corporation, the value of the warp of the sample was investigated. When the sample was placed on a plane such that one main surface on which the conductive portion was arranged was upward and the other main surface was downward, the value of the warp was measured with the state of being convex on one main surface side being negative and the state of being convex on the other main surface side being positive.

[0047] Furthermore, for the obtained samples, the adhesion strength of the conductive part 20 to the main body part 10 was investigated. Specifically, a Ni plating layer with a thickness of 2 - 3 μm was applied to a conductive part with a width of 2 mm and a length of 5 mm, and a 5 - mm - long part of a metal L - shaped holding member with a width of 0.7 mm, a length of 5 mm, and a height of 2.5 mm in a direction perpendicular to the length direction was joined by brazing. Next, the holding member and the sample were each held, and the tip portion with a height of 2.5 mm of the holding member was pulled in a direction perpendicular to the interface between the conductive part and the main body part, and the load at the time when the conductive part was peeled off from the main body part was measured as the adhesion strength. A digital force gauge (model number ZP200N) manufactured by IMADA Co., Ltd. was used for the measurement. It can be judged that the adhesion strength is sufficient if it is 9.8 N (1 kgf) or more, and insufficient if it is less than 9.8 N. The above experimental results are shown in Table 1.

[0048]

Table 1

[0049] FIG. 6 shows a secondary electron image of a cross section near the interface between the conductive portion 20 and the main body portion 10 of Samples 5 and 2, a state in which the secondary electron image of the conductive portion 20 is binarized, and a state in which elliptical fitting is performed based on the binarized image. In the left column of FIG. 6, a photograph (secondary electron image) of the cross section of each sample is shown, in the middle column, the result of binarizing the secondary electron image of the cross section of the conductive portion, and in the right column, the result of elliptical fitting of the binarized result is shown. The white region of the secondary electron image is the metal component (W), and the black region is the glass phase. The black region of the binarization result is the glass phase. The region surrounded by the black line in the elliptical fitting result is the glass phase.

[0050] Referring to FIG. 6, it can be seen that compared with Sample 2, the area ratio of the glass phase of Sample 5 is small, and the ratio of the glass phase 32 having a small aspect ratio is high. Based on such image data, the image data of the conductive portion 20 was binarized and elliptically fitted to calculate the area ratio and aspect ratio of the glass phase 32.

[0051] Referring to Table 1, in Sample 1, the area ratio of the glass phase is outside the range of 3% or more and 20% or less which is the range of the present disclosure. Specifically, the area ratio of the glass phase exceeds 20%. As a result, the resistivity becomes 0.2 Ω·μm or more, and Sample 1 is not preferable from the viewpoint of electrical resistance. In Samples 2 and 3, the area ratio of the glass phase 32 is smaller than that of Sample 1. As a result, the resistivity is less than 0.15 Ω·μm, and it can be said that it is in a preferable state from the viewpoint of electrical resistance. However, the ratio of the number of glass phases having an aspect ratio of 1.5 or less and the ratio of the number of glass phases having an aspect ratio of 2 or less among the total number of glass phases are less than 40% and 65% respectively. As a result, the absolute value of the warpage value exceeds 30 μm, and Samples 2 and 3 are not preferable from the viewpoint of warpage.

[0052] In contrast, in Samples 4 to 12, the area ratio of the glass phase 32 is within the range of 3% or more and 20% or less, which is the range of the present disclosure. Also, the ratio of the number of glass phases 32 having an aspect ratio of 1.5 or less and the ratio of the number of glass phases 32 having an aspect ratio of 2 or less among all the glass phases 32 are 40% or more and 65% or more, respectively. As a result, these samples are judged as A or B in all items of resistivity, warpage, and adhesion strength, and it can be said that favorable characteristics are obtained. In particular, regarding the samples in which the area ratio of the glass phase 32 is 8% or more and 20% Below or less, since the adhesion strength is 19.6 N (2 kgf) or more, it can be said that more favorable characteristics are obtained.

[0053] In Sample 13, the area ratio of the glass phase is outside the range of 3% or more and 20% or less, which is the range of the present disclosure. Specifically, the area ratio of the glass phase is less than 3%. As a result, the adhesion strength is less than 9.8 N (less than 1 kgf), and from the viewpoint of the adhesion strength of the conductive part 20 to the main body part 10, Sample 13 cannot be said to be favorable. From this, the formation of the glass phase 32 derived from the sintering aid of the main body part 10 contributes to an increase in the adhesion strength of the conductive part 20 to the main body part 10, and it is confirmed that when the glass phase 32 is reduced to below the lower limit of the range of the present disclosure, the adhesion strength becomes insufficient.

[0054] Also, in Samples 14 to 16, Mo is adopted as the first metal component instead of W in Samples 1 to 13. From these experimental results, even when Mo is adopted as the first metal component, the same tendency as when W is adopted is confirmed.

[0055] From the above experimental results, it is confirmed that according to the ceramic wiring member of the present disclosure, it is possible to achieve both reduction of warpage and reduction of the electrical resistance of the conductive part.

[0056] In the above-described embodiment, the case where the main body portion 10 includes the side wall portion 12 has been described. However, the ceramic wiring member of the present disclosure is not limited thereto, and may include a flat plate-shaped main body portion 10 in which the side wall portion 12 is omitted. Such a ceramic wiring member is used as a ceramic wiring board on which electronic components are mounted. Further, on the surfaces of the internal terminals 21 and the external terminals 25, a plating layer made of a Ni (nickel) layer, an Au (gold) layer, or the like may be formed from the viewpoint of reducing contact resistance and the like.

[0057] It should be understood that the embodiments and examples disclosed this time are illustrative in all respects and not restrictive in any way. The scope of the present disclosure is defined not by the above description but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims be included.

Explanation of Reference Numerals

[0058] 1 Ceramic wiring member, 10 Main body portion, 10A Cavity, 11 Bottom wall portion, 11A First main surface, 11B Second main surface, 12 Side wall portion, 12A First end surface, 12B Second end surface, 20 Conductive portion, 21 Internal terminal, 22 First connection portion, 23 Internal wiring, 24 Second connection portion, 25 External terminal, 26 Upper terminal, 27 Third connection portion, 28 Lower terminal, 29 Fourth connection portion, 30 Intermediate terminal, 31 Conductive phase, 31A Void, 32 Glass phase, 121 Protrusion, 121A Second surface, 121B First surface, 121C Third surface.

Claims

1. A ceramic main body having a plate-shaped portion, and a conductive portion disposed in contact with the plate-shaped portion, wherein the structure of the conductive portion comprises a conductive phase made of a metal component containing at least one of W and Mo and having a plurality of voids dispersed away from each other, and a glass phase that fills the plurality of voids and has an area ratio of 3% or more and 20% or less in a cross-section in the thickness direction of the plate-shaped portion, and in a cross-section in the thickness direction of the plate-shaped portion, the ratio of the number of the glass phases having an aspect ratio of 1.5 or less to the total number of the glass phases is 40% or more. A ceramic wiring member.

2. The ceramic wiring member according to claim 1, wherein in a cross-section in the thickness direction of the plate-shaped portion, the ratio of the number of the glass phases having an aspect ratio of 2 or less to the total number of the glass phases is 65% or more.

3. The conductive portion includes a first portion in contact with a first main surface of the plate-shaped portion, and a second portion in contact with a second main surface located on the side opposite to the first main surface in the thickness direction of the plate-shaped portion. The ceramic wiring member according to any one of claims 1 and 2.

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