JPWO2013001973A1 - Manufacturing method of multilayer ceramic substrate - Google Patents

Abstract

In order to increase the bonding strength of the surface electrode in the multilayer ceramic substrate, an oxide such as alumina is added to the conductive paste for forming the surface electrode, and it is allowed to react with the glass component in the ceramic body during firing. However, in the region of the surface electrode in contact with the via conductor, there is a problem that the penetration of the glass component is hindered and the sintering of the surface electrode does not proceed sufficiently. In order to solve this problem, the surface layer via conductor (16) connected to the surface electrode (14) is formed so as to penetrate the surface electrode (14) and one end thereof is exposed from the surface electrode (14). To do. Preferably, a plating film (15) or the like is formed on the surface electrode (14) and one end portion of the surface via conductor (16).

Description

  The present invention relates to a multilayer ceramic substrate, a manufacturing method thereof, and an electronic component module configured using the multilayer ceramic substrate, and particularly to a connection structure between a surface electrode and a via conductor of the multilayer ceramic substrate.

  For example, in Japanese Patent Application Laid-Open No. 2004-362822 (Patent Document 1), a ceramic body composed of a plurality of laminated ceramic layers, a surface electrode formed on the main surface of the ceramic body, and a ceramic layer are provided. A multilayer ceramic substrate is described that includes a via conductor formed to penetrate in the thickness direction and connected to a surface electrode.

  FIG. 9 is a cross-sectional view of the multilayer ceramic substrate 1 having the above configuration.

  The multilayer ceramic substrate 1 includes a ceramic body 3 formed by laminating a plurality of ceramic layers 2. In the following description, in order to distinguish among the plurality of ceramic layers 2 that are particularly arranged in the surface layer portion, they are referred to as “surface layer ceramic layers” and are denoted by reference numerals “2 (A)”. To. On the other hand, the ceramic layers 2 other than the surface ceramic layer 2 (A) are referred to as “inner ceramic layers” and are denoted by reference numerals “2 (B)”. In FIG. 9, only a part of each of the main surface direction and the stacking direction of the multilayer ceramic substrate 1 is illustrated. For example, the surface ceramic layer 2 (A ) Is illustrated, but the surface ceramic layer disposed on the lower main surface side is not illustrated.

  A surface electrode 4 is formed on the main surface of the ceramic body 3. A plating film 5 is formed on the surface electrode 4. A surface layer via conductor 6 is connected to the surface electrode 4. The surface layer via conductor 6 is formed so as to penetrate at least the surface layer ceramic layer 2 (A) in the thickness direction. In FIG. 9, the surface layer via conductor 6 passes through the surface layer ceramic layer 2 (A) and the inner layer ceramic layer 2 (B) therebelow.

  The multilayer ceramic substrate 1 also includes via conductors 7 other than the surface layer via conductors 6. The via conductor 7 is formed inside the ceramic body 3 so as to penetrate the specific ceramic layer 2 in the thickness direction. An internal conductor film 8 is formed along the interface between the ceramic layers 2 so as to connect the via conductor 7 and the surface via conductor 6.

  Although not shown, the surface electrode 4 is used when mounting a mounting component to be mounted on the multilayer ceramic substrate 1 such as an IC chip or another chip component, or when mounting the multilayer ceramic substrate 1 on the motherboard. Or used. That is, the mounting component or the mother board is electrically connected to the surface electrode 4 through the plating film 5 and a conductive bonding material such as solder applied thereon and mechanically. Be joined.

  The surface electrode 4 is formed by sintering a conductive paste at the same time as firing for sintering the ceramic body 3. In particular, the surface electrode 4 is electrically conductive in order to enhance the above-described mechanical bonding function. A paste to which an oxide such as alumina is added is used. Oxides such as alumina are sintered by reacting with the glass component in the ceramic body 3 in the firing step for sintering the ceramic body 3, whereby the surface electrode 4, the ceramic body 3, and the like. To improve the bonding strength between.

  Focusing on the behavior of the glass component in the ceramic body 3, referring to FIG. 9, the surface electrode 4 is in contact with the ceramic body 3 at the peripheral edge, but the surface layer is at the center. It can be seen that it is in contact with the via conductor 6 and not in contact with the ceramic body 3. For this reason, in the area | region which contact | connects the surface layer via conductor 6, the penetration | infiltration of the glass component from the ceramic element | base_body 3 to the surface electrode 4 is not fully made | formed. As a result, in this region, the surface electrode 4 may not be sufficiently sintered and may be sparse.

  When the surface electrode 4 has a sparse part as described above, the strength of the surface electrode 4 to the ceramic body 3 is lowered and the moisture resistance of the multilayer ceramic substrate 1 is lowered. In particular, when the plating film 5 is formed, the plating solution is trapped in a sparse part at the time of plating, which causes problems such as solder voids in the subsequent mounting component mounting process or the mounting process on the motherboard. .

  Moreover, since the specific resistance of the surface electrode 4 to which an oxide such as alumina is added is higher than that to which no oxide is added, an electrical connection portion through the surface electrode 4 is electrically Characteristic degradation may occur.

JP 2004-362822 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a multilayer ceramic substrate and a method for manufacturing the same, and an electronic component module configured using the multilayer ceramic substrate, which can solve the above-described problems.

  The present invention relates to a ceramic body composed of a plurality of laminated ceramic layers, a surface electrode formed on the main surface of the ceramic body, and a via conductor formed so as to penetrate the ceramic layer in the thickness direction. The via conductor is formed on a multilayer ceramic substrate including a surface layer via conductor that penetrates at least a surface layer ceramic layer on which a surface electrode is formed and is connected to the surface electrode among a plurality of ceramic layers. In order to solve the technical problem described above, the surface layer via conductor penetrates the surface electrode, and one end thereof is exposed from the surface electrode.

  In the multilayer ceramic substrate according to the present invention, preferably, a plating film is formed on the surface electrode and one end of the surface via conductor. According to the present invention, since the sparse portion caused by insufficient sintering does not occur in the surface electrode, the plating film is formed on the surface electrode and on one end portion of the surface via conductor as described above. Even if it is done, the plating solution is not trapped in the sparse part, and therefore, it is less likely to cause defects such as solder voids in the subsequent mounting component mounting process or mounting process on the motherboard. it can.

  Alternatively, in the multilayer ceramic substrate according to the present invention, a conductor film is preferably formed by baking on the surface electrode and one end of the surface via conductor. In this case, the strength of the surface electrode can be improved.

  Preferably, the surface electrode includes a sintered body of conductive component powder and oxide powder as an inorganic substance. Thereby, the adhesiveness of the surface electrode to the ceramic body can be further improved. In this case, the surface layer via conductor includes a sintered body of conductive component powder and oxide powder as an inorganic substance, and the content of the oxide powder in the inorganic substance in the surface electrode is determined by the oxide powder in the inorganic substance in the surface layer via conductor. It is preferable that the content is higher than the content.

  Moreover, it is preferable that a surface electrode and a ceramic body contain a glass component, and the glass component contained in a surface electrode is the same composition as the glass component contained in a ceramic body.

  The present invention is also directed to an electronic component module including the multilayer ceramic substrate described above and an electronic component electrically connected to the surface electrode and the surface layer via conductor via solder.

  The present invention is further directed to a method for producing a multilayer ceramic substrate.

  According to a first aspect of the method for manufacturing a multilayer ceramic substrate according to the present invention, a step of preparing a plurality of ceramic green sheets and a surface electrode on the ceramic green sheet for the surface layer to be arranged on the surface layer among the plurality of ceramic green sheets A plurality of ceramics including the surface layer ceramic green sheet so that the surface electrode is located on at least one main surface, and a surface layer via conductor penetrating the surface layer ceramic green sheet in the thickness direction. In the step of forming the surface layer via conductor, the step of forming the surface layer via conductor, and the step of forming the surface layer via conductor by laminating and pressure bonding the green sheet, A surface via conductor is formed so as to penetrate both sides in the thickness direction. That.

  According to a second aspect of the present invention, there is provided a multilayer ceramic substrate manufacturing method comprising: a step of preparing a plurality of ceramic green sheets; and a thickness of a ceramic green sheet for a surface layer to be disposed on a surface layer among the plurality of ceramic green sheets. Forming a surface via conductor penetrating in the direction, forming a surface electrode connected to the surface layer via conductor on the ceramic green sheet for the surface layer, and surface layer so that the surface electrode is located on at least one main surface In the step of forming a surface layer via conductor, comprising a step of producing a layered product by laminating and pressing a plurality of ceramic green sheets including ceramic green sheets for use, and a step of firing the layered product The conductor is formed using a conductive paste containing 25% by volume or more of inorganic powder to form a surface electrode. In the process, the thickness of the surface electrode is set to 10 μm or less after firing, and the step of manufacturing the laminate is performed in such a manner that the surface via conductor breaks through the surface electrode and exposes its end portion from the surface electrode. And a step of pressure-bonding the ceramic green sheet.

  Note that the thickness of the surface electrode is not a value measured using, for example, a fluorescent X-ray film thickness meter, but a value obtained by measuring the actual product as it is.

  The method for manufacturing a multilayer ceramic substrate according to the present invention preferably further includes a step of forming a plating film on the exposed end portion of the surface electrode and the surface layer via conductor after the step of firing the laminate. Alternatively, preferably, the method further includes a step of forming a conductive paste film on the exposed end portions of the surface electrode and the surface via conductor before the step of firing the laminate, and the step of firing the laminate includes the conductive paste A step of baking the film.

  In the method for producing a multilayer ceramic substrate according to the present invention, the ceramic green sheet preferably contains a glass component, and in the step of firing the laminate, the glass component is preferably sucked up by the surface electrode. Thereby, the glass component contained in the surface electrode has the same composition as the glass component contained in the ceramic body, but when such an embodiment is adopted, the adhesion between the surface electrode and the ceramic body is more improved. Can be increased.

  The method for producing a multilayer ceramic substrate according to the present invention comprises a step of forming a via conductor penetrating a ceramic green sheet other than the surface layer ceramic green sheet in the thickness direction, and a conductor film on the ceramic green sheet other than the surface layer ceramic green sheet. And a forming step.

  According to the present invention, the surface electrode can be in contact with the ceramic body in the entire region. Therefore, when the ceramic body contains a glass component, the surface electrode can sufficiently infiltrate the glass component from the ceramic body in the entire region thereof, and can sufficiently advance the sintering. As a result, the bonding strength of the surface electrode to the ceramic body can be maintained high, and the moisture resistance of the multilayer ceramic substrate can be maintained high.

  Further, according to the present invention, the surface via conductor penetrates the surface electrode, and one end of the surface via conductor is exposed from the surface electrode. Therefore, the electrical connection to the mounting component or the motherboard does not go through the surface electrode. Both can be guaranteed at least by the surface via conductors. Therefore, in order to increase the bonding strength of the surface electrode, even if an oxide such as alumina is added to increase the specific resistance, electrical characteristics are deteriorated at the electrical connection portion through the surface electrode. This can be prevented.

  As described above, according to the present invention, the surface electrode has a mechanical joining function with the mounting component or the motherboard, and the surface via conductor has an electrical connection function with the mounting component or the motherboard. As described above, by sharing the roles, it is possible to realize a multilayer ceramic substrate capable of exhibiting excellent functions in both mechanical joining and electrical connection.

It is sectional drawing which shows a part of multilayer ceramic substrate by 1st Embodiment of this invention. FIG. 2 is a cross-sectional view illustrating a method for manufacturing the multilayer ceramic substrate shown in FIG. 1, and in particular, a process applied to a surface layer ceramic green sheet. FIG. 2 is a cross-sectional view illustrating a method for manufacturing the multilayer ceramic substrate shown in FIG. 1, and in particular, a process performed on an inner layer ceramic green sheet. FIG. 10 is a plan view for explaining a second embodiment of the present invention and showing a modification of the positional relationship between the surface electrode and the surface via conductor. It is sectional drawing which shows a part of multilayer ceramic substrate by 3rd Embodiment of this invention. FIG. 6 is a cross-sectional view illustrating a manufacturing method of the multilayer ceramic substrate shown in FIG. 5, and in particular, a process applied to the surface ceramic green sheet and a pressure bonding process. It is sectional drawing which shows a part of multilayer ceramic substrate by 4th Embodiment of this invention. It is sectional drawing which shows an example of the electronic component module comprised using the multilayer ceramic substrate which concerns on this invention. It is sectional drawing which shows a part of conventional multilayer ceramic substrate 1 interesting for this invention.

  A first embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the multilayer ceramic substrate 11 includes a ceramic body 13 in which a plurality of ceramic layers 12 are laminated, as in the case of the conventional multilayer ceramic substrate 1 shown in FIG. Also in the following description, when distinguishing among the ceramic layers 12 that are particularly arranged in the surface layer portion, they are referred to as “ceramic layers for the surface layer” and are denoted by reference numerals “12 (A)”. I will decide. On the other hand, the ceramic layers 12 other than the surface ceramic layer 12 (A) are referred to as “inner ceramic layers” and are denoted by reference numerals “12 (B)”. Also in FIG. 1, only a part of each of the main surface direction and the stacking direction of the multilayer ceramic substrate 11 is shown. For example, the surface ceramic layer 12 (on the upper main surface side of the ceramic body 13) ( Although A) is illustrated, the surface ceramic layer disposed on the lower main surface side is not illustrated.

  A surface electrode 14 is formed on the main surface of the ceramic body 13. A surface layer via conductor 16 is connected to the surface electrode 14. The surface layer via conductor 16 is formed not only to penetrate the surface layer ceramic layer 12 (A) in the thickness direction but also to penetrate the surface electrode 14 in the thickness direction. In FIG. 1, the surface layer via conductor 16 also penetrates the inner layer ceramic layer 12 (B) below the surface layer ceramic layer 12 (A).

  A plating film 15 is formed on the surface electrode 14 and on one end of the surface layer via conductor 16 exposed from the surface electrode 14. In FIG. 1, the exposed end surface of the surface via conductor 16 is flush with the upper surface of the surface electrode 4, but may be positioned below the upper surface of the surface electrode 4 instead of being flush with the upper surface.

  The multilayer ceramic substrate 11 also includes via conductors 17 other than the surface layer via conductors 16. The via conductor 17 is formed inside the ceramic body 13 so as to penetrate the specific ceramic layer 12 in the thickness direction. Further, an internal conductor film 18 is formed along the interface between the ceramic layers 12 so as to connect the via conductor 17 and the surface via conductor 16.

  The multilayer ceramic substrate 11 is manufactured as follows, for example.

  First, a plurality of ceramic green sheets to be the ceramic layer 12 are prepared. FIG. 2 shows a surface layer ceramic green sheet 22 (A) to be the surface layer ceramic layer 12 (A), and FIG. 3 shows another layer, that is, the inner layer ceramic layer 12 (B). An inner layer ceramic green sheet 22 (B) is shown. The ceramic green sheet 22 is obtained by, for example, adding a binder, a plasticizer, and a solvent to a ceramic raw material powder containing barium oxide, silicon oxide, and alumina, and mixing the resulting slurry into a sheet forming method such as a doctor blade method. It is obtained by forming into a sheet shape on a carrier film using As the ceramic raw material powder, one that generates glass upon firing may be used, or a sintering aid such as glass may be included.

Next, in the surface layer ceramic green sheet 22 (A), as shown in FIG. 2 (1), the surface electrode 14 is formed thereon using a conductive paste. For example, screen printing is applied to the formation of the surface electrode 14. As the conductive paste, a paste containing a conductive component powder and an oxide powder is preferably used as an inorganic substance. As the conductive component powder, for example, a powder mainly composed of a conductor such as Cu, Ag, Pt, Pd, Ni, or Au can be used. As the oxide powder, for example, Al ₂ O ₃ powder is representative, but other powders made of oxides of Si, Mg, Zr, Mn, Nb, Ti, or Ba can be used.

  The content of the conductive component powder in the inorganic material contained in the conductive paste used for forming the surface electrode 14 is 80 to 98.5% by volume, that is, the content of the oxide powder is 1.5. It is preferably ˜20% by volume. When the content of the oxide powder is less than 1.5% by volume, the amount of metal oxide that can react with the glass in the ceramic body 13 is small, so that the bonding strength of the surface electrode 14 to the ceramic body 13 is high. Tend to be lower. On the other hand, when the content of the oxide powder exceeds 20% by volume, the metal oxide is excessively increased, the glass in the ceramic body 13 is not sucked up sufficiently, and the bonding strength tends to be lowered. Moreover, there exists a tendency for plating property to fall.

  Next, as shown in FIG. 2 (2), a through-hole 23 penetrating the surface layer ceramic green sheet 22 (A) and the surface electrode 14 in the thickness direction is formed by punching or laser processing.

  Next, as shown in FIG. 2 (3), the through hole 23 is filled with a conductive paste, whereby the surface via conductor 16 is formed. As the conductive paste for the surface layer via conductor 16, for example, a paste containing a conductive component powder mainly composed of a conductor such as Cu or Ag is used. In addition, conductive component powders mainly composed of a conductor such as Pt, Pd, Ni, and Au can be used. Moreover, the conductive paste may contain a metal oxide powder in addition to the metal powder as an inorganic substance.

  In this case, the content of the oxide powder in the inorganic material contained in the conductive paste for the surface via conductor 16 is the content of the oxide powder in the inorganic material contained in the conductive paste for the surface electrode 14 described above. Is preferably lower. For example, the content of the conductive component powder in the inorganic substance contained in the conductive paste for the surface layer via conductor 16 is 25 to 58% by volume, that is, the content of the oxide powder is 42 to 75% by volume. It is preferable that

  Thus, the content rate of the oxide powder in the inorganic material contained in the conductive paste for the surface layer via conductor 16 is greater than the content rate of the oxide powder in the inorganic material contained in the conductive paste for the surface electrode 14. However, the surface via conductor 16 is more conductive than the surface electrode 14 after firing because the glass from the ceramic body 13 permeates the surface electrode 14 and is sintered. It will be excellent.

  On the other hand, for the inner layer ceramic green sheet 22 (B), for example, the following processing is performed. As an example, an inner layer ceramic green sheet 22 (B) to be the ceramic layer 2 illustrated at the bottom in FIG. 1 will be described.

  First, as shown in FIG. 3A, a through hole 24 penetrating through the inner layer ceramic green sheet 22 (B) in the thickness direction is formed by punching or laser processing.

  Next, as shown in FIG. 3B, the through-hole 4 is filled with a conductive paste, and a via conductor 17 is formed. Here, as the conductive paste, the same conductive paste as that for the surface via conductor 16 described above can be used.

  Next, as shown in FIG. 3 (3), the internal conductor film 18 electrically connected to the via conductor 17 described above is formed on the ceramic green sheet 22 (B) for the inner layer using a conductive paste. Is done. Here, as the conductive paste, for example, a paste containing a conductive component powder whose main component is a conductor such as Cu or Ag is used.

  Next, the surface electrode 14 is positioned on various surfaces so that the surface electrode 14 is positioned on one main surface, or when the surface electrode 14 is formed on both main surfaces of the ceramic body 12. As described above, the ceramic green sheet 22 (A) for the surface layer and the ceramic green sheet 22 (B) for the inner layer are laminated in a predetermined order and pressed to form an unsintered laminate.

  Next, the laminate is fired. As a result, a sintered ceramic body 13 is obtained. In this firing step, not only the ceramic green sheet 22 but also the conductive paste for forming the surface electrode 14, the surface layer via conductor 16, the via conductor 17 and the internal conductor film 18 are sintered.

At this time, the metal oxide such as Al ₂ O ₃ in the conductive paste forming the surface electrode 14 is sintered by reacting with the glass component in the ceramic body 13, thereby The bonding strength with the ceramic body 13 is improved. Therefore, after firing, both the surface electrode 14 and the ceramic body 13 contain a glass component, and the glass component contained in the surface electrode 14 and the glass component contained in the ceramic body 13 have the same composition. Become.

  The surface electrode 14 is in contact with the ceramic body 13 in the entire region. Therefore, the penetration of the glass component from the ceramic body 13 to the surface electrode 14 is sufficiently spread. As a result, the entire surface electrode 14 is sintered densely, and the bonding strength of the surface electrode 14 to the ceramic body 13 is increased. Enhanced. Further, it contributes to improvement of moisture resistance of the multilayer ceramic substrate 11.

  In addition, a shrinkage suppression layer mainly composed of a hardly sinterable material that does not substantially sinter at the firing temperature of the laminate is disposed on both principal surfaces or one principal surface of the laminate subjected to the firing step and fired. The above firing step may be performed by applying a so-called constrained firing method.

  Next, a plating film 15 is formed on the exposed end portions of the surface electrode 14 and the surface via conductor 16. The plating film 15 is composed of, for example, a Ni plating layer and an Au plating layer thereon. As described above, since the entire surface electrode 14 is densely sintered, the plating solution is not easily trapped by the surface electrode 14 in this plating step, and therefore, in the subsequent mounting component mounting step or mounting step on the motherboard, Problems such as solder voids can be made difficult to occur.

  As described above, the multilayer ceramic substrate 11 is obtained. In this multilayer ceramic substrate 11, the surface via conductor 16 penetrates the surface electrode 14, and one end thereof is exposed from the surface electrode 14. Even if 14 is not interposed, it can be ensured by at least the surface via conductor 16. Therefore, in order to increase the bonding strength of the surface electrode 14, there is no particular problem even if an oxide such as alumina is added to increase the specific resistance.

  Regarding the planar positional relationship between the surface electrode 14 and the surface layer via conductor 17, in the first embodiment, the surface layer via conductor 17 is disposed within the range where the surface electrode 14 is formed. As in the second embodiment, the surface layer via conductors 17 may be arranged in a state of partially protruding from the range where the surface electrode 14 is formed.

  Next, a third embodiment of the present invention will be described with reference to FIGS. 5 and 6, elements corresponding to those shown in FIGS. 1 to 3 described above are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 5, the multilayer ceramic substrate 31 has a surface electrode 34 and a surface via conductor 36 provided in relation to the surface ceramic layer 12 (A) as compared with the multilayer ceramic substrate 11 according to the first embodiment. The form is different. This difference in form stems from the difference in manufacturing method. Therefore, the manufacturing method will be described below.

  First, as shown in FIG. 6 (1), a surface layer via conductor 36 is formed on the surface layer ceramic green sheet 22 (A), and then a surface electrode 34 connected to the surface layer via conductor 36 is connected to the surface layer via conductor 36. It is formed so as to cover the end face. Here, the surface layer via conductor 36 is formed using a conductive paste containing 25% by volume or more of an inorganic powder, and the thickness of the surface electrode 34 is set to 10 μm or less after firing.

  On the other hand, the ceramic green sheet 22 (B) for the inner layer is processed in the same manner as in the first embodiment shown in FIG.

  Next, as in the case of the first embodiment, when the surface electrode 34 is located on one main surface or when the surface electrode 34 is formed on both main surfaces of the ceramic body 12, The surface layer ceramic green sheet 22 (A) and the inner layer ceramic green sheet 22 (B) are laminated in a predetermined order and pressure-bonded so that the surface electrode 34 is positioned on various surfaces. An unsintered laminated body 37 as shown in 2) is produced.

  In the above-described process, particularly the crimping process, the surface layer via conductor 36 breaks through the surface electrode 34, and an end portion thereof is exposed from the surface electrode 34. As a result, a state is obtained in which the surface layer via conductor 36 penetrates the surface electrode 34 and one end thereof is exposed from the surface electrode 34. In order to surely realize the behavior of the surface via conductor 36 and the surface electrode 34, as described above, the surface via conductor 36 is formed using a conductive paste containing 25% by volume or more of inorganic powder, The thickness of the surface electrode 34 is set to 10 μm or less after firing. These conditions can be confirmed by experimental examples described later. In addition, it is preferable that content of the inorganic substance powder contained in the electrically conductive paste for forming the surface layer via conductor 36 is 95 volume% or less. The thickness of the surface electrode 34 is preferably 1 μm or more after firing.

  Thereafter, as in the case of the first embodiment, the firing step and the plating step are performed, and the multilayer ceramic substrate 31 shown in FIG. 5 is obtained.

  In the above third embodiment, there is a condition that the conductive paste for the surface via conductor 36 contains 25% by volume or more of inorganic powder, and a condition that the thickness of the surface electrode 34 is 10 μm or less after firing. In order to confirm that it is appropriate, as shown in Table 1 below, samples with various changes in the “inorganic matter content in the surface via conductor” and the “surface electrode thickness” were prepared. The surface electrode 34 was pierced, and it was investigated whether or not a state where one end thereof was exposed from the surface electrode 34 was obtained.

  For each sample, the number of samples is 15, and if the breakthrough can be confirmed in all the samples, “○” is displayed in the “Breakthrough” column of Table 1. If even one breakthrough fails, “×” is displayed. displayed.

  Referring to Table 1, in Sample 3, the “thickness of the surface electrode” was 11 μm exceeding 10 μm, and therefore “breakthrough” was “x”. In sample 4, the “inorganic content in the surface via conductor” was 20% by volume less than 25% by volume, and “breakthrough” was “x”.

  On the other hand, according to Samples 1, 2, and 5 to 7, the “surface electrode thickness” was 10 μm or less and the “inorganic matter content in the surface via conductor” was 25% by volume or more. "Became" ○ ".

  Next, with reference to FIG. 7, a fourth embodiment of the present invention will be described. In FIG. 7, elements corresponding to the elements shown in FIG. 1 described above are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 7, in the multilayer ceramic substrate 41, a conductor film 45 is formed by baking between the surface electrode 14 and the plating film 15 formed in the multilayer ceramic substrate 11 according to the first embodiment. It is characterized by.

  The conductive film 45 is formed of a conductive paste so as to cover the surface of the surface electrode 14 and the end surface of the surface via conductor 16 after the surface electrode 14 and the surface layer via conductor 16 are formed on the surface ceramic green sheet 22 (A). Formed. Next, the ceramic green sheet 22 (A) for surface layers and the ceramic green sheet 22 (B) for inner layers are laminated | stacked in a predetermined | prescribed order, and an unbaking laminated body is produced by crimping, and this is baked. Then, the multilayer ceramic substrate 41 is obtained by forming the plating film 15 on the exposed portions of the conductor film 45 and the surface electrode 14.

  Oxide powder may be added to the surface electrode 14 in order to improve adhesion to the ceramic body 13, but in this case, the strength of the surface electrode 14 itself may be weakened. On the other hand, when the conductor film 45 is formed, the strength of the surface electrode 14 and the conductor film 45 as a whole can be improved. In particular, the amount of oxide powder contained in the conductor film 45 is preferably smaller than the amount of oxide powder contained in the surface electrode. Further, when a pure metal such as pure copper is used in the conductor film 45, the strength of the conductor film 45 can be improved due to its ductility.

  The conductor film 45 may be formed in advance on the surface layer ceramic green sheet 22 (A) as described above, or after laminating and pressing each ceramic green sheet to produce an unfired laminate, A conductive paste film may be applied to the exposed end portions of the electrode 13 and the surface via conductor 16.

  Note that the conductive film 45 may be formed by forming and baking a conductive paste film on the exposed ends of the surface electrode 13 and the surface via conductor 16 after firing the laminate. Although the plating film 15 is formed in FIG. 7, the plating film 15 may not be formed.

  FIG. 8 is a cross-sectional view showing an example of an electronic component module configured using the multilayer ceramic substrate according to the present invention. It should be understood that the multilayer ceramic substrate shown in FIG. 8 is the multilayer ceramic substrate 11 partially shown in FIG. Therefore, in the following, the multilayer ceramic substrate 11 shown in FIG. 1 will be described as being shown in FIG. 8, and in FIG. 8, elements corresponding to those shown in FIG. A duplicate description is omitted.

  The electronic component module 51 shown in FIG. 8 includes a multilayer ceramic substrate 11. On the upper main surface of the multilayer ceramic substrate 11, for example, surface mount type electronic components 52 and 53 are mounted. One electronic component 52 is, for example, a chip capacitor, and is electrically connected to the plating film 15 formed on the surface electrode 14 and the surface layer via conductor 16 via the solder 54. The other electronic component 53 is a semiconductor chip, for example, and is electrically connected to the plating film 15 formed on the surface electrode 14 and the surface layer via conductor 16 via the solder bump 55.

  The surface electrode 14 located on the lower principal surface of the multilayer ceramic substrate 11 has the same structure as the surface electrode 14 located on the upper principal surface.

11, 31, 41 Multilayer ceramic substrate 12 Ceramic layer 13 Ceramic body 14, 34 Surface electrode 15 Plated film 16, 36 Surface layer via conductor 22 Ceramic green sheet 45 Conductor film 51 Electronic component module 52, 53 Electronic component 54 Solder 55 Solder bump

SUMMARY OF THE INVENTION The present invention relates to the production how the multilayer ceramic board, in particular, to a method of forming a connecting portion between the surface electrode and the via conductor of the multilayer ceramic substrate.

Accordingly, an object of the present invention can solve the problems described above, it is to try to provide a manufacturing how the multilayer ceramic board.

In order to solve the above technical problems, a method for manufacturing a multilayer ceramic substrate according to the present invention includes a step of preparing a plurality of ceramic green sheets, and a ceramic green for a surface layer to be arranged on the surface layer among the plurality of ceramic green sheets. A step of forming a surface via conductor penetrating in the thickness direction on the sheet; a step of forming a surface electrode connected to the surface layer via conductor on the ceramic green sheet for surface layer; and the surface electrode is located on at least one main surface As described above, a step of forming a multilayer body by laminating and pressing a plurality of ceramic green sheets including a ceramic green sheet for surface layer and a step of firing the multilayer body, and forming a surface layer via conductor The surface via conductor is formed using a conductive paste containing 25% by volume or more of inorganic powder, In the step of forming the surface electrode, the thickness of the surface electrode is set to be 10 μm or less after firing, and in the step of manufacturing the laminate, the surface via conductor breaks through the surface electrode and the end portion is exposed from the surface electrode. In other words, the method includes a step of pressure bonding a plurality of ceramic green sheets.

According to the multilayer ceramic substrate obtained by the manufacturing method according to the present invention, the surface electrode can be in contact with the ceramic body in the entire region. Therefore, when the ceramic body contains a glass component, the surface electrode can sufficiently infiltrate the glass component from the ceramic body in the entire region thereof, and can sufficiently advance the sintering. As a result, the bonding strength of the surface electrode to the ceramic body can be maintained high, and the moisture resistance of the multilayer ceramic substrate can be maintained high.

Further, according to the multilayer ceramic substrate obtained by the manufacturing method according to the present invention, the surface layer via conductor penetrates the surface electrode and the one end thereof is exposed from the surface electrode. This electrical connection can be ensured by at least the surface via conductors without using the surface electrodes. Therefore, in order to increase the bonding strength of the surface electrode, even if an oxide such as alumina is added to increase the specific resistance, electrical characteristics are deteriorated at the electrical connection portion through the surface electrode. This can be prevented.

It is sectional drawing which shows a part of multilayer ceramic substrate used as the 1st reference example of this invention. FIG. 2 is a cross-sectional view illustrating a method for manufacturing the multilayer ceramic substrate shown in FIG. 1, and in particular, a process applied to a surface layer ceramic green sheet. FIG. 2 is a cross-sectional view illustrating a method for manufacturing the multilayer ceramic substrate shown in FIG. 1, and in particular, a process performed on an inner layer ceramic green sheet. It is a top view for demonstrating the 2nd reference example of this invention, and shows the modification of the positional relationship of a surface electrode and a surface layer via conductor. It is sectional drawing which shows a part of multilayer ceramic substrate manufactured by the manufacturing method by one Embodiment of this invention. FIG. 6 is a cross-sectional view illustrating a manufacturing method of the multilayer ceramic substrate shown in FIG. 5, and in particular, a process applied to the surface ceramic green sheet and a pressure bonding process. It is sectional drawing which shows a part of multilayer ceramic substrate by the 3rd reference example of this invention. It is sectional drawing which shows an example of the electronic component module comprised using the multilayer ceramic substrate which concerns on this invention. It is sectional drawing which shows a part of conventional multilayer ceramic substrate 1 interesting for this invention.

Prior to describing the manufacturing method according to the present invention, first, a first reference example useful for understanding the present invention will be described with reference to FIGS.

Regarding the planar positional relationship between the surface electrode 14 and the surface layer via conductor 17, in the first reference example , the surface layer via conductor 17 is disposed within the range where the surface electrode 14 is formed. As in the second reference example , the surface layer via conductor 17 may be disposed in a state of partially protruding from the range where the surface electrode 14 is formed.

Next, an embodiment of the present invention will be described with reference to FIGS. 5 and 6, elements corresponding to those shown in FIGS. 1 to 3 described above are denoted by the same reference numerals, and redundant description is omitted.

As shown in FIG. 5, the multilayer ceramic substrate 31 is different from the multilayer ceramic substrate 11 according to the first reference example in that the surface electrode 34 and the surface via conductor 36 provided in relation to the surface ceramic layer 12 (A). The form is different. This difference in form stems from the difference in manufacturing method. Therefore, the manufacturing method will be described below.

On the other hand, the inner layer ceramic green sheet 22 (B) is processed in the same manner as in the first reference example shown in FIG.

Next, as in the case of the first reference example , when the surface electrode 34 is located on one main surface or when the surface electrode 34 is formed on both main surfaces of the ceramic body 12, The surface layer ceramic green sheet 22 (A) and the inner layer ceramic green sheet 22 (B) are laminated in a predetermined order and pressure-bonded so that the surface electrode 34 is located on each main surface . An unsintered laminated body 37 as shown in (2) is produced.

Thereafter, as in the case of the first reference example , the firing step and the plating step are performed, and the multilayer ceramic substrate 31 shown in FIG. 5 is obtained.

In the implementation form described above, provided that the conductive paste for the surface layer via conductor 36 includes inorganic powders more than 25 vol%, and the thickness of the surface electrode 34, provided that after firing is 10μm or less is appropriate In order to confirm the existence, as shown in Table 1 below, samples with various changes in the “inorganic matter content in the surface via conductor” and the “surface electrode thickness” were prepared. It was investigated whether or not a state in which the electrode 34 was pierced and one end thereof was exposed from the surface electrode 34 was obtained.

Next, a third reference example of the present invention will be described with reference to FIG. In FIG. 7, elements corresponding to the elements shown in FIG. 1 described above are denoted by the same reference numerals, and redundant description is omitted.

As shown in FIG. 7, the multilayer ceramic substrate 41 has a conductor film 45 formed by baking between the surface electrode 14 and the plating film 15 formed in the multilayer ceramic substrate 11 according to the first reference example . It is characterized by.

FIG. 8 is a cross-sectional view showing an example of an electronic component module configured using the multilayer ceramic substrate according to the present invention. The multilayer ceramic substrate shown in FIG. 8 is the multilayer ceramic substrate 11 partially shown in FIG. 1, but may be replaced with the multilayer ceramic substrate 31 partially shown in FIG. In the following description, it is assumed that the multilayer ceramic substrate 11 shown in FIG. 1 is shown in FIG. 8, and in FIG. 8, elements corresponding to the elements shown in FIG. A duplicate description is omitted.

Claims (13)

A ceramic body composed of a plurality of laminated ceramic layers, a surface electrode formed on the main surface of the ceramic body, and a via conductor formed so as to penetrate the ceramic layer in the thickness direction. Prepared,
The via conductor includes a surface layer via conductor that penetrates at least a ceramic layer for surface layer in which the surface electrode is formed among the plurality of ceramic layers and is connected to the surface electrode,
The surface layer via conductor penetrates the surface electrode, and one end thereof is exposed from the surface electrode.
Multilayer ceramic substrate.   The multilayer ceramic substrate according to claim 1, further comprising a plating film formed on the surface electrode and on the one end of the surface via conductor.   The multilayer ceramic substrate according to claim 1, further comprising a conductive film formed by baking formed on the surface electrode and the one end portion of the surface layer via conductor.   The multilayer ceramic substrate according to claim 1, wherein the surface electrode includes a sintered body of conductive component powder and oxide powder as an inorganic substance.   The surface via conductor includes a sintered body of conductive component powder and oxide powder as an inorganic substance, and the content of the oxide powder in the inorganic substance in the surface electrode is determined by the inorganic substance in the inorganic substance in the surface via conductor. The multilayer ceramic substrate according to claim 4, wherein the content is higher than the content of the oxide powder.   The said surface electrode and the said ceramic element | base_body contain a glass component, and the glass component contained in the said surface electrode is the same composition as the glass component contained in the said ceramic element | base_body. Multilayer ceramic substrate.   An electronic component module comprising: the multilayer ceramic substrate according to claim 1; and an electronic component electrically connected to the surface electrode and the surface via conductor via solder. Preparing a plurality of ceramic green sheets;
Of the plurality of ceramic green sheets, forming a surface electrode on the ceramic green sheet for the surface layer to be disposed on the surface layer;
Forming a surface layer via conductor penetrating the surface layer ceramic green sheet and the surface electrode in a thickness direction;
Stacking the plurality of ceramic green sheets including the ceramic green sheet for surface layer, and press-bonding so that the surface electrode is located on at least one main surface;
And a step of firing the laminate. Preparing a plurality of ceramic green sheets;
Among the plurality of ceramic green sheets, a step of forming a surface layer via conductor penetrating in a thickness direction on a surface layer ceramic green sheet to be disposed on a surface layer;
Forming a surface electrode connected to the surface via conductor on the surface ceramic green sheet;
Stacking the plurality of ceramic green sheets including the ceramic green sheet for surface layer, and press-bonding so that the surface electrode is located on at least one main surface;
And firing the laminate.
In the step of forming the surface via conductor, the surface via conductor is formed using a conductive paste containing 25% by volume or more of inorganic powder,
In the step of forming the surface electrode, the thickness of the surface electrode is set to 10 μm or less after firing,
The step of producing the laminated body includes a step of pressure bonding the plurality of ceramic green sheets so that the surface layer via conductor pierces the surface electrode and exposes an end portion thereof from the surface electrode.
A method for producing a multilayer ceramic substrate.   The method for manufacturing a multilayer ceramic substrate according to claim 8 or 9, further comprising a step of forming a plating film on the exposed end portion of the surface electrode and the surface layer via conductor after the step of firing the multilayer body.   Prior to the step of firing the laminate, the method further includes the step of forming a conductive paste film on the exposed end of the surface electrode and the surface via conductor, and the step of firing the laminate comprises the conductive paste The multilayer ceramic substrate according to claim 8, comprising a step of baking a film.   The method for producing a multilayer ceramic substrate according to claim 8, wherein the ceramic green sheet contains a glass component, and the glass component is sucked up by the surface electrode in the step of firing the laminate.   A step of forming a via conductor penetrating in the thickness direction through the ceramic green sheet other than the surface layer ceramic green sheet, and a step of forming a conductor film on the ceramic green sheet other than the surface layer ceramic green sheet, The method for producing a multilayer ceramic substrate according to claim 8.

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