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

Ceramic wiring materials

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

[0002] Ceramic wiring members are known that include a ceramic main body having a plate-shaped portion and a conductive portion made of a material containing metal and arranged in contact with the plate-shaped portion. Such ceramic wiring members are used as members for holding electronic components. The conductive portion constitutes part of the path of current to or from the electronic component. In such ceramic wiring members, it is important to reduce the electrical resistance of the conductive portion. However, due to the difference in the linear expansion coefficient between the ceramic that constitutes the main body and the metal that constitutes the conductive portion, warping may occur in ceramic wiring substrates. If this warping becomes excessive, problems such as peeling of the conductive portion from the main body may occur. Therefore, reducing warping is desirable.

[0003] For example, the warpage can be reduced by introducing a ceramic glass phase into the conductive portion to bring the coefficient of linear expansion of the conductive portion closer to that of the main body. It is known that a glass phase, which is composed of a ceramic component that is added mainly as a sintering aid to the ceramic that constitutes the main body, is formed in the conductive portion during the manufacturing process of the ceramic wiring member (see, for example, Japanese Patent 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 believed that by forming an appropriate amount of glass phase, it is possible to reduce warpage while keeping the increase in electrical resistance within an acceptable range.

[0004] Japanese Patent Application Laid-Open No. 2003-347710

[0005] However, even if the proportion of the glass phase in the conductive portion is set within an appropriate range as described above, there are cases in which the electrical resistance increases beyond an allowable range or warpage cannot be sufficiently reduced.

[0006] An object of the present disclosure is to provide a ceramic wiring member that can achieve both reduced warping and reduced electrical resistance in the conductive portion.

[0007] A ceramic wiring member according to the present disclosure includes a ceramic body having a plate-shaped portion and a conductive portion disposed in contact with the plate-shaped portion. The conductive portion has a structure including a conductive phase made of a metal component including at least one of W (tungsten) and Mo (molybdenum) and having a plurality of voids dispersed apart from one another, and a glass phase filling the voids and occupying an area ratio of 3% to 20% in a cross section in the thickness direction of the plate-shaped portion. In the cross section in the thickness direction of the plate-shaped portion, the proportion of the number of glass phases having an aspect ratio of 1.5 or less out of the total number of glass phases is 40% or more.

[0008] According to the ceramic wiring member, it is possible to provide a ceramic wiring member that can achieve both reduced warpage and reduced electrical resistance of the conductive portion.

[0009] Fig. 1 is a schematic cross-sectional view showing the structure of a ceramic wiring member. Fig. 2 is a schematic cross-sectional view showing the structure near the interface between a main body portion (plate-shaped portion) and a conductive portion. Fig. 3 is a flowchart showing an outline of a method for manufacturing a ceramic wiring member. Fig. 4 is a schematic cross-sectional view showing the structure of a ceramic wiring member in embodiment 2. Fig. 5 is a schematic cross-sectional view showing the structure of a ceramic wiring member in embodiment 3. Fig. 6 is a diagram for explaining analysis of the state of existence of a glass phase in a conductive portion.

[0010] [Summary of the Embodiments] First, embodiments of the present disclosure will be described. A ceramic wiring member according to a first aspect of the present disclosure includes a ceramic main body having a plate-shaped portion and a conductive portion disposed in contact with the plate-shaped portion. The structure of the conductive portion includes a conductive phase made of a metal component containing at least one of W and Mo, the conductive phase having a plurality of voids dispersed apart from one another, and a glass phase filling the voids and occupying an area ratio of 3% to 20% in a cross section in the thickness direction of the plate-shaped portion. In a cross section in the thickness direction of the plate-shaped portion, the proportion of glass phases having an aspect ratio of 1.5 or less out of the total number of glass phases is 40% or more.

[0011] In the ceramic wiring member of the first aspect, in a cross section of the plate-like portion in the thickness direction, the proportion 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 present inventors have investigated the reasons why electrical resistance increases beyond the allowable range and warpage cannot be sufficiently reduced even when the proportion of the glass phase in the conductive portion is within an appropriate range, and have obtained the following findings.

[0013] The electrical resistance and warpage values ​​are affected by the shape of the glass phase filling the voids. Specifically, when the shape of each glass phase is far from spherical, i.e., when the aspect ratio of the glass phase is large in the cross section of the thickness direction of the plate-shaped portion, the increase in the electrical resistance and warpage values ​​is significant. The reasons for this are thought to be, for example, as follows: When the aspect ratio of the glass phase is large, stress tends to concentrate near the longitudinal tip of the glass phase. Therefore, when stress is applied to the conductive portion during the manufacturing process of the ceramic wiring member after firing the main body portion and the conductive portion, stress concentrates near the tip, causing microcracks in the conductive phase. The occurrence of these cracks increases the electrical resistance of the conductive portion. Furthermore, when the aspect 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. This prevents the glass phase from shrinking (or expanding) isotropically three-dimensionally. As a result, non-uniform stress occurs, resulting in an increase in the warpage value.

[0014] In contrast, when the aspect ratio of the glass phase is close to 1, i.e., when the shape of the glass phase is close to spherical, the presence of the glass phase has a small effect on increases in electrical resistance and warpage. More specifically, in the cross section in the thickness direction of the plate-shaped portion, the proportion of glass phases having an aspect ratio of 1.5 or less to the total number of glass phases is 40% or more, preferably 40% or more and the proportion of glass phases having an aspect ratio of 2 or less is 65% or more, thereby reducing the effect of the presence of the glass phase on increases in electrical resistance and warpage. As a result, the ceramic wiring member of the present disclosure can provide a ceramic wiring member that can achieve both reduced warpage and reduced electrical resistance of the conductive portion.

[0015] Here, in the present application, the aspect ratio of the glass phase refers to the ratio of the major axis to the minor axis of the ellipse with the smallest area that contains each glass phase. This aspect ratio can be obtained, for example, by observing the thickness direction cross section of the plate-shaped conductive portion using a scanning electron microscope, binarizing the obtained image data using image processing software, determining the ellipse with the smallest area that contains each glass phase, and calculating the ratio of the major axis to the minor axis (major axis / minor axis) of the ellipse. The image data is acquired so that 150 or more glass phases are included in the image data. In the present application, the glass phase may include, in addition to the glass component contained in the main body portion, crystals of the ceramic main component (alumina) contained in the main body portion and a small amount of metal component contained in the conductive portion. The glass phase may also include glass components that are not contained in the main body portion.

[0016] In the ceramic wiring member, the conductive portion may include a first portion that contacts the first main surface of the plate-shaped portion and a second portion that contacts the second main surface located on the opposite side of the plate-shaped portion from the first main surface in the thickness direction of the plate-shaped portion. In this way, the first and second main surfaces of the plate-shaped portion are electrically connected by the conductive portion with reduced electrical resistance, thereby providing a high-performance ceramic wiring member that can accommodate power savings and higher communication speeds.

[0017] [Specific Examples of Embodiments] Next, specific examples 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 designated by the same reference characters, and their description will not be repeated.

[0018] 1 is a schematic cross-sectional view showing the structure of a ceramic wiring member according to one embodiment of the present disclosure. Referring to FIG. 1, a ceramic wiring member 1 of the present embodiment includes a ceramic body 10 and a conductive portion 20. The ceramic constituting body 10 is not particularly limited, but may be, for example, aluminum oxide (Al ２ O ３The ceramic constituting the main body 10 may contain, as a sintering aid, at least one glass component selected from the group consisting of an oxide containing Si, an oxide containing Ca, an oxide containing Mg, an oxide containing Mn, and an oxide containing Ba.

[0019] The main body 10 includes a bottom wall 11 serving as a first plate-shaped portion and a side wall 12 serving as a second plate-shaped portion. 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 when viewed in a direction perpendicular to the first main surface 11A) is, for example, rectangular.

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

[0021] In this 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 to the internal wiring 23 and a second connection portion 24 connecting the internal wiring 23 to the external terminal 25. The internal wiring 23, the first connection portion 22, and the second connection portion 24 form a third portion connecting the internal terminal 21 as the first portion and the external terminal 25 as the 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-shaped portion. As a modification of the first connecting portion 22 and the second connecting portion 24, for example, castellations may be provided on the side surfaces of the bottom wall portion 11, and conductive portions may be provided on the surfaces of the castellations.

[0022] 2 , the structure of at least one, and preferably all, of the internal terminal 21, external terminal 25, internal wiring 23, first connecting portion 22, and second connecting portion 24 constituting the conductive portion 20 is made of a metal component containing at least one of W and Mo, and includes a conductive phase 31 having a plurality of voids 31A dispersed apart from one another, and a glass phase 32 filling the plurality of voids 31A and having an area fraction of 3% to 20% in the cross section in the thickness direction of the bottom wall portion 11. Having an area fraction of the glass phase of 20% or less suppresses an increase in the electrical resistance of the conductive portion 20, while having an area fraction of the glass phase of 3% or more, preferably 8% or more, reduces the difference in the linear expansion coefficient between the conductive portion 20 and the main body portion 10. The glass phase 32 in the conductive portion 20 basically penetrates from the main body portion by capillary action during sintering, but the glass phase 32 may also contain glass components not contained in the main body portion 10. From the viewpoint of electrical resistance and strength, the voids 31A not filled with the glass phase 32 are preferably 5% or less, more preferably 1% or less, in terms of area ratio in the cross section of the conductive portion 20. In the cross section (cross section shown in FIG. 2 ) in the thickness direction of the bottom wall portion 11, the proportion of the number of glass phases 32 having an aspect ratio of 1.5 or less to the total number of glass phases 32 is 40% or more. Regarding the glass phase 32, the major axis of the ellipse obtained by ellipse fitting described below is preferably 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 voids 31A in the conductive portion 20 are suppressed, and the strength of the conductive portion 20 is increased. Furthermore, by setting the major axis of the ellipse to 4 μm or less, the electrical resistance of the conductive portion 20 can be reduced.

[0023] In the ceramic wiring member 1 of this embodiment, in a cross section in the thickness direction of the bottom wall portion 11 serving as a plate-like portion, the proportion of glass phases 32 having an aspect ratio of 1.5 or less to the total number of glass phases 32 is 40% or more. This reduces the effect of the presence of glass phases 32 on increases in the electrical resistance and warpage of the conductive portion 20. As a result, the ceramic wiring member 1 of this embodiment is a ceramic wiring member that achieves both reduced warpage and reduced electrical resistance of the conductive portion 20.

[0024] In the ceramic wiring member 1 of the present embodiment, the proportion of glass phases having an aspect ratio of 2 or less to the total number of glass phases 32 is preferably 65% ​​or more. This more reliably reduces the influence of the presence of glass phases 32 on increases in the electrical resistance and warpage of the conductive portion 20. As a result, the ceramic wiring member 1 of the present embodiment can be a ceramic wiring member that more reliably achieves both reduced warpage and reduced electrical resistance of the conductive portion 20.

[0025] Next, an example of a method for manufacturing the ceramic wiring member 1 according to this embodiment will be described. FIG. 3 is a flowchart showing an outline of the method for manufacturing the ceramic wiring member. Referring to FIG. 3, in the method for manufacturing the ceramic wiring member 1 according to this embodiment, a green sheet preparation step is first carried out as step S10. In this step S10, a green sheet to be used as the main body 10 is prepared. Specifically, Al, which is the main component of the ceramic powder constituting the main body 10, is prepared. ２ O ３ The sintered powder, sintering aid powder, and resin, solvent, etc. that do not constitute the main body 10 (i.e., disappear during firing) are mixed in a ball mill to obtain a slurry. This slurry is processed into green sheets by a doctor blade method. In this way, green sheets to become the main body 10 are obtained. Here, referring to FIG. 1 , a plurality of green sheets having a rectangular planar shape are prepared as green sheets to become the bottom wall 11. A plurality of green sheets to become the side wall 12 are also prepared. As the green sheets to become the side wall 12, annular green sheets having a rectangular planar shape and with the portion (center portion) corresponding to the cavity 10A removed are prepared.

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

[0027] This paste is printed, for example, by screen printing, on the green sheets prepared in step S10. As a result, referring to Fig. 1, the following green sheets are prepared as the bottom wall portion 11: a green sheet having the paste printed in an area corresponding to external terminal 25, a green sheet having the paste printed in an area corresponding to second connection portion 24, a green sheet having the paste printed in an area corresponding to internal wiring 23, a green sheet having the paste printed in an area corresponding to first connection portion 22, and a green sheet having the paste printed in an area corresponding to internal terminal 21. After drying, the green sheets are laminated in this order. Drying can be performed, for example, by heating to 110°C and maintaining the temperature for 5 minutes.

[0028] Furthermore, a plurality of green sheets (annular green sheets with the portions corresponding to the cavities 10A removed) prepared in step S10 to become the side wall portions 12 are further stacked. In this manner, a stack of green sheets is obtained.

[0029] Next, a firing step is carried out as step S30. In this step, 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 containing a mixture of hydrogen, nitrogen, and water vapor. The heating temperature is selected from a temperature range that can suppress the formation of an intermetallic compound phase consisting of an intermetallic compound of the first metal component and the second metal component in the structure of the conductive portion 20, taking into consideration the sufficient progress of sintering. The ceramic wiring member 1 of this embodiment can be manufactured by the above procedure.

[0030] In the manufacturing method of the ceramic wiring member 1 of this embodiment, in step S20, a second metal component is used in addition to the first metal component as the metal component constituting the conductive phase 31. The second metal component is added at a ratio of 0.1% to 10% of the first metal component. The remainder of the metal components other than the first and second metal components consists only of unavoidable impurities. The addition of the second metal component can prevent a glass phase containing a sintering aid constituting the main body 10 from penetrating into the conductive portion 20 in step S30. The addition of the second metal component can also promote sintering of the metal powder, which is the raw material powder of the conductive portion 20. This prevents the glass phases 32 filling adjacent voids 31A from connecting to each other, thereby reducing the aspect ratio of the glass phases 32. The manufacturing method of the ceramic wiring member 1 of this embodiment is not limited to the above-described manufacturing method, but the above-described manufacturing method can easily manufacture the ceramic wiring member 1 of this embodiment.

[0031] Second Embodiment Next, a second embodiment of the present disclosure will be described. FIG. 4 is a schematic cross-sectional view showing the structure of a ceramic wiring member according to the second embodiment. FIG. 4 is a view corresponding to FIG. 1 referred to in the description of the first embodiment. Referring to FIGS. 4 and 1, the ceramic wiring member 1 of the second embodiment basically has the same configuration and produces the same effects as the first embodiment. However, the ceramic wiring member 1 of the second embodiment differs from the first embodiment mainly in the arrangement and structure of the conductive portions. The second embodiment will be described below, focusing on the differences from the first embodiment.

[0032] 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 arranged in contact with the first end face 12A, a lower terminal 28 as a second portion arranged in contact with the second end face 12B, and a third connecting portion 27 connecting the upper terminal 26 and the lower terminal 28. The lower terminal 28 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, and the third connecting portion 27 are all parts of the conductive portion 20 arranged in contact with the side wall portion 12 as the second plate-like portion.

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

[0034] The ceramic wiring member 1 of this embodiment can also achieve the same effects as those of Embodiment 1. The ceramic wiring member 1 of this embodiment can be manufactured in the same manner as Embodiment 1, mainly except for changing the arrangement of the conductive portion 20. In this embodiment, the bottom wall portion 11 is made of ceramic, which is an insulator, but a conductive material such as a metal may be used as the material for the bottom wall portion 11.

[0035] Third Embodiment Next, a third embodiment of the present disclosure will be described. FIG. 5 is a schematic cross-sectional view showing the structure of a ceramic wiring member according to the third embodiment. FIG. 5 corresponds to FIG. 1 referred to in the description of the first embodiment. Referring to FIGS. 5 and 1, the ceramic wiring member 1 of the third embodiment basically has the same configuration as the first embodiment and achieves the same effects. However, the ceramic wiring member 1 of the third embodiment differs from the first embodiment mainly in the structure of the main body and the arrangement and structure of the conductive portion. The third embodiment will be described below, focusing on the differences from the first embodiment.

[0036] 5 , the side wall 12 of the ceramic wiring member 1 according to the third embodiment includes a protruding portion 121 that protrudes toward 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 11, a second surface 121A located on the opposite side of the bottom wall 11 from the first surface 121B in the thickness direction of the bottom wall 11, and a third surface 121C that is a tip surface connecting the first surface 121B and the second surface 121A. A region of the first surface 121B that includes a tip connected to the third surface 121C faces the first main surface 11A, while the other region (a region corresponding to the vicinity of the base 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] At least one, preferably all, of the upper terminal 26, lower terminal 28, third connecting portion 27, intermediate terminal 30, and fourth connecting portion 29 constituting the conductive portion 20 contain a first metal component as a main component, which is at least one of W and Mo, and at least one second metal component selected from the group consisting of Ni, Co, and Fe, in a total amount of 0.1% to 10% of the first metal component, similar to the inner terminal 21 of the first embodiment. Furthermore, at least one, preferably all, of the structures of the upper terminal 26, lower terminal 28, and third connecting portion 27 constituting the conductive portion 20 contain a conductive phase composed of an alloy of the first metal component and the second metal component, similar to the inner terminal 21 of the first embodiment. Note that the term "alloy" as used herein refers to a solid solution of the first metal component and the second metal component as well as a mixture of the first metal component and the second metal component that is not solid-solutioned. Furthermore, the structure of at least one, and preferably all, of the upper terminal 26, lower terminal 28, third connection portion 27, intermediate terminal 30, and fourth connection portion 29 that constitute the conductive portion 20 contains a glass phase 32 consisting of a ceramic component with an area ratio of 3% to 20% in the cross section of the conductive portion 20.

[0039] The ceramic wiring member 1 of this embodiment can also achieve the same effects as those of the first embodiment. The ceramic wiring member 1 of this embodiment can be manufactured in the same manner as the first embodiment, except that the structure of the main body 10 and the arrangement of the conductive portion 20 are mainly changed. In this embodiment, the bottom wall 11 is made of ceramic, which is an insulator, but a conductive material such as metal may be used as the material for the bottom wall 11. Although the above embodiment illustrates the shape of the main body 10, the shape of the main body of the present disclosure is not limited to this. The main body may have various shapes, such as a rectangular parallelepiped shape, a spherical shape, or a film-like shape.

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

[0041] The conductive portion 20 was formed in contact with the main body portion 10 using the same procedure as in the manufacturing method described in the above embodiment, and the resistivity of the conductive portion 20, the warpage of the ceramic wiring member 1, and the adhesive strength of the conductive portion 20 to the main body portion 10 were investigated. ２ O ３ powder and SiO as a sintering aid ２ A green sheet containing powder of at least one selected from the group consisting of CaO, MgO, MnO and BaO, a resin, a 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 performed by heating to 110°C and holding for 5 minutes. At least one of W and Mo was used as the first metal component. In addition, the amounts of Ni, Co, and Fe added as the second metal component were changed in order to change the area ratio and aspect ratio of the glass phase. Samples without the second metal component were also prepared.

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

[0044] For 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-shaped portion, the proportion of the number of glass phases with an aspect ratio of 1.5 or less to the total number of glass phases, and the proportion of the number of glass phases with an aspect ratio of 2 or less were investigated. Specifically, for the obtained samples, the cross section of the conductive portion 20 was observed with a scanning electron microscope. The obtained image data was then binarized into black and white using image processing software, and the areas of the glass phases 32 were summed to calculate the area ratio of the glass phase 32 in the conductive portion 20. In addition, an ellipse with the smallest area that contained each glass phase was determined (ellipse fitting), and the ratio of the major axis to the minor axis of the ellipse (major axis / minor axis) was calculated to obtain the aspect ratio of each glass phase. Then, based on the obtained aspect ratio of each glass phase, the number of glass phases with an aspect ratio of 1.5 or less was calculated. Based on these results, the ratio of the number of glass phases with an aspect ratio of 1.5 or less to the total number of glass phases within the field of view observed with the scanning electron microscope and the ratio of the number of glass phases with an aspect ratio of 2 or less were calculated. ImageJ (free software) was used for the image processing.

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

[0046] The obtained samples were also measured for warpage. Specifically, the warpage value of the samples was investigated using a three-dimensional shape measuring device (model number VK-X1000) manufactured by Keyence Corporation. The sample was placed on a flat surface so that one main surface on which the conductive portion was arranged was facing up and the other main surface was facing down, and the warpage value was measured by defining a state in which one main surface was convex as negative and a state in which the other main surface was convex as positive.

[0047] Furthermore, the adhesion strength of the conductive portion 20 to the main body 10 was investigated for the resulting samples. Specifically, a 2-3 μm thick Ni plating layer was applied to a 2 mm wide, 5 mm long conductive portion, and a 5 mm long portion of a 0.7 mm wide, 5 mm long, and 2.5 mm high metal L-shaped holding member was brazed to the conductive portion. The holding member and the sample were then held together, and the 2.5 mm high tip of the holding member was pulled in a direction perpendicular to the interface between the conductive portion and the main body. The load at which the conductive portion peeled from the main body was measured as the adhesion strength. Measurements were performed using a digital force gauge (model ZP200N) manufactured by Imada Corporation. Adhesion strength of 9.8 N (1 kgf) or greater was considered sufficient, while adhesion strength below 9.8 N was considered insufficient. The experimental results are shown in Table 1.

[0048] In Table 1, resistivity was evaluated as A for less than 0.15 Ω·μm, B for 0.15 Ω·μm or more but less than 0.2 Ω·μm, and C for 0.2 Ω·μm or more. For warpage, absolute values ​​of less than 30 μm were evaluated as A, and 30 μm or more were evaluated as C. For adhesion strength, 9.8 N or more was evaluated as A, and less than 9.8 N was evaluated as C. For the overall evaluation, samples that were evaluated as C in any of the three evaluation items were evaluated as C, and samples that were not evaluated as C in any of the items were evaluated as A. In other words, A means excellent, C means poor, and B means somewhere in between. An example of an analysis of the state of the glass phase 32 in the conductive portion 20 using image processing software is shown in FIG. 6 .

[0049] FIG. 6 shows secondary electron images of the cross section near the interface between the conductive portion 20 and the main body portion 10 of Samples 5 and 2, the binarized secondary electron images of the conductive portion 20, and the results of ellipse fitting based on the binarized images. The left column of FIG. 6 shows photographs (secondary electron images) of the cross section of each sample, the center column shows the results of binarizing the secondary electron images of the cross section of the conductive portion, and the right column shows the results of ellipse fitting the binarized results. The white areas in the secondary electron images are the metal component (W), and the black areas are the glass phase. The black areas in the binarized results are the glass phase. The area surrounded by a black line in the ellipse fitting results is the glass phase.

[0050] 6 , it can be seen that the area ratio of the glass phase in Sample 5 is smaller and the proportion of the glass phase 32 with a small aspect ratio is higher than in Sample 2. Based on this image data, binarization and ellipse fitting were performed on the image data of the conductive portion 20, and the area ratio and aspect ratio of the glass phase 32 were calculated.

[0051] Referring to Table 1, in Sample 1, the area ratio of the glass phase is outside the range of 3% to 20% in the present disclosure. Specifically, the area ratio of the glass phase exceeds 20%. As a result, the resistivity is 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, which is preferable from the viewpoint of electrical resistance. However, the proportion of the number of glass phases having an aspect ratio of 1.5 or less and the proportion of the number of glass phases having an aspect ratio of 2 or less out of 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 fraction of the glass phase 32 was within the range of 3% to 20%, which is the range of the present disclosure, and the percentage of the number of glass phases 32 with an aspect ratio of 1.5 or less and the percentage of the number of glass phases 32 with an aspect ratio of 2 or less were 40% or more and 65% or more, respectively. As a result, these samples were evaluated as A or B in all items of resistivity, warpage, and adhesion strength, and it can be said that they obtained favorable characteristics. In particular, it can be said that the samples with an area fraction of the glass phase 32 of 8% to 20% obtained more favorable characteristics because the adhesion strength was 19.6 N (2 kgf) or more.

[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 Sample 13 cannot be said to be preferable from the viewpoint of the adhesion strength of the conductive part 20 to the main body part 10. This confirms that 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 that when the glass phase 32 is reduced to a level below the lower limit of the range of the present disclosure, the adhesion strength becomes insufficient.

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

[0055] The above experimental results confirm that the ceramic wiring member of the present disclosure can achieve both reduced warpage and reduced electrical resistance of the conductive portion.

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

[0057] It should be understood that the embodiments and examples disclosed herein are illustrative in all respects and are not limiting in any respect. The scope of the present disclosure is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

[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 wiring member comprising: a ceramic body having a plate-shaped portion; and a conductive portion arranged 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 apart from one another; and a glass phase filling the voids and accounting for an area ratio of 3% to 20% in a cross section in the thickness direction of the plate-shaped portion; wherein the proportion of the number of glass phases having an aspect ratio of 1.5 or less out of the total number of glass phases in the cross section in the thickness direction of the plate-shaped portion is 40% or more.

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

3. A ceramic wiring member according to claim 1 or claim 2, wherein the conductive portion includes a first portion in contact with a first main surface of the plate-like portion, and a second portion in contact with a second main surface located on the opposite side of the first main surface in the thickness direction of the plate-like portion.

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