JP2008078454A - Multilayer ceramic substrate and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To further increase the strength of a multilayer ceramic substrate, by increasing the strength of sides of its ceramic laminate, when the multilayer ceramic substrate whose flexural strength is increased by developing compressing stress on superficial ceramic parts in a cooling process, after firing by setting the thermal expansion coefficient of the superficial ceramic parts to be smaller than those of internal layer ceramic parts. <P>SOLUTION: The ceramic layered body 15 has a layered structure which is comprising two superficial ceramic parts 13 and 14, exhibiting a first thermal expansion coefficient and the internal layer ceramic part 12, exhibiting a second thermal expansion coefficient larger than the first thermal expansion coefficient layered in between. In this case, a side ceramic part 26, exhibiting a third thermal expansion coefficient smaller than the second thermal expansion coefficient, is provided along at least a part of a side 21 that extends in the direction of the layer stack and is connected with at least one superficial ceramic part 14. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a multilayer ceramic substrate and a method for manufacturing the same, and more particularly, to a multilayer ceramic substrate and a method for manufacturing the same, in which a difference in thermal expansion coefficient is provided between a surface layer ceramic portion and an inner layer ceramic portion to increase strength. Is.

  A multilayer ceramic substrate that is of interest to the present invention is described, for example, in JP-A-6-29664 (Patent Document 1). In Patent Document 1, as shown in FIG. 11, a low-temperature fired multilayer ceramic substrate 1 made of glass and the balance is crystalline, and the thermal expansion coefficient of the outermost layer 2 is made smaller than the thermal expansion coefficient of the inner layer 3. And what made the sum total of the thickness of the outermost layer 2 of the front and back smaller than the thickness of the inner layer 3 is described. By adopting such a configuration, compressive stress is generated in the outermost layer 2 on the front and back sides in the cooling process after firing, so that the bending strength of the multilayer ceramic substrate 1 is improved.

  However, the strength of the side surface 4 extending in the stacking direction of the multilayer ceramic substrate 1 is not particularly improved. More specifically, the side surface 4 of the multilayer ceramic substrate 1 has a different coefficient of thermal expansion, and therefore, an interface 5 between the outermost layer 2 and the inner layer 3 made of different materials is exposed. Tends to be the starting point of destruction such as cracks.

In particular, when the side electrode 6 is formed on the side surface 4 so as to straddle the interface 5, the multilayer ceramic substrate 1 is mounted on a mother substrate 7 (shown by imaginary lines) such as a printed wiring board. In this state, the side electrode 6 may be peeled off or the multilayer ceramic substrate 1 may be broken from the vicinity of the side electrode 6 because it cannot withstand an impact such as dropping or bending, or thermal stress.
JP-A-6-29664

  Therefore, an object of the present invention is to provide a multilayer ceramic substrate that can solve the above-described problems.

  Another object of the present invention is to provide a preferred method for producing the multilayer ceramic substrate described above.

  This invention has a laminated structure in which an inner layer ceramic part having a second thermal expansion coefficient larger than the first thermal expansion coefficient is sandwiched between two surface layer ceramic parts having a first thermal expansion coefficient. Firstly directed to a multilayer ceramic substrate having a ceramic laminate, and in order to solve the above technical problem, at least one surface ceramic portion along at least a part of a side surface extending in the laminating direction of the ceramic laminate A side ceramic portion having a third thermal expansion coefficient smaller than the second thermal expansion coefficient in a state of being connected to each other is provided.

  It is preferable that the third thermal expansion coefficient of the side ceramic part is substantially equal to the first thermal expansion coefficient of the surface ceramic part. In addition, when the third thermal expansion coefficient and the first thermal expansion coefficient are not equivalent, the third thermal expansion coefficient is preferably larger than the first thermal expansion coefficient.

  In the multilayer ceramic substrate according to the present invention, it is sufficient that, of the two surface ceramic portions, only the surface layer ceramic portion located on the mother substrate side in mounting is connected to the side ceramic portion.

  When the multilayer ceramic substrate according to the present invention further includes a side electrode formed along the side surface of the ceramic laminate, the side ceramic portion may be provided so as to be in contact with at least a part of the peripheral portion of the side electrode. preferable.

  It is preferable that the surface layer ceramic portion, the inner layer ceramic portion and the side surface ceramic portion are made of a low temperature sintered ceramic. In this case, when the multilayer ceramic substrate according to the present invention includes a conductor pattern provided in association with the surface layer ceramic portion and / or the inner layer ceramic portion, the conductor pattern preferably contains silver or copper as a main component.

  The multilayer ceramic substrate according to the present invention may further include a surface-mounted electronic component that is mounted on the surface of the ceramic laminate that is opposite to the mother substrate during mounting.

  The present invention is also directed to a method of manufacturing a multilayer ceramic substrate as described above.

  According to a first preferred embodiment of the method for producing a multilayer ceramic substrate according to the present invention, an unfired surface ceramic part that becomes a surface ceramic part when fired and an unfired inner layer that becomes an inner ceramic part when fired A non-sintered assembly that is an aggregate of a plurality of unsintered ceramic laminates having a structure in which ceramic parts are laminated and an unsintered side ceramic part that becomes a side ceramic part when fired. The method includes a step of manufacturing a substrate, a step of firing an unfired aggregate substrate, and a step of dividing the aggregate substrate so that the ceramic portion is exposed to the side surface. Here, either the firing step or the dividing step may be performed first.

  In a second preferred embodiment, an unfired surface layer ceramic part that becomes a surface layer ceramic part when fired and an unfired inner layer ceramic part that becomes an inner layer ceramic part when fired are laminated. A step of producing a fired ceramic laminate, and by pressing protrusions from the outside into the unfired surface layer ceramic part, a part of the unfired surface layer ceramic part is deformed inward, and the unfired surface layer ceramic part A step of forming an unfired side surface ceramic portion that becomes a side surface ceramic portion when fired, and a step of firing an unfired ceramic laminate.

  In a third preferred embodiment, an unfired surface layer ceramic part that becomes a surface layer ceramic part when fired and an unfired inner layer ceramic part that becomes an inner layer ceramic part when fired are laminated. A step of producing a fired ceramic laminate, a step of imparting an unfired side ceramic portion that becomes a side ceramic portion when fired to at least a part of a side surface of the unfired ceramic laminate, and an unfired side surface And a step of firing the unfired ceramic laminate provided with the ceramic portion.

  According to the multilayer ceramic substrate according to the present invention, the first thermal expansion coefficient of the surface ceramic part is made smaller than the second thermal expansion coefficient of the inner ceramic part, so that the surface ceramic part is cooled in the cooling process after firing. In addition to increasing the bending strength of the multilayer ceramic substrate, the inner layer is also connected to at least one surface ceramic portion on the side surface of the ceramic laminate. Since the side ceramic part having the third thermal expansion coefficient smaller than the second thermal expansion coefficient of the ceramic part is provided, it is possible to make it difficult to cause a crack such as a crack starting from the side.

  Therefore, when the multilayer ceramic substrate according to the present invention is mounted on the mother substrate, even if an impact such as dropping or bending, or thermal stress is applied, the multilayer ceramic substrate has sufficient strength to withstand these. Can do.

  As described above, when the multilayer ceramic substrate is mounted on the mother substrate, if the side ceramic portion is connected only to the surface ceramic portion located on the mother substrate side, the effect can be sufficiently exerted. .

  When the multilayer ceramic substrate includes a side electrode, if the side ceramic part is provided so as to be in contact with at least a part of the peripheral part of the side electrode, the strength at the peripheral part of the side electrode is improved. Is less likely to occur.

  When the surface ceramic part, inner layer ceramic part, and side ceramic part are made of low-temperature sintered ceramic, firing and co-firing to sinter the ceramic laminate are possible even if silver or copper is used as the main component of the conductor pattern. In addition, it is possible to reduce the electrical resistance of the conductor pattern and to reduce the loss due to the electrical resistance of the conductor pattern.

  According to the first embodiment of the method for manufacturing a multilayer ceramic substrate according to the present invention, the manufacturing process can be carried out in the state of an aggregate substrate that is an aggregate of a plurality of ceramic laminates. A substrate can be manufactured.

  According to the second embodiment of the method for manufacturing a multilayer ceramic substrate according to the present invention, the side ceramic part is formed by deforming a part of the unfired surface layer ceramic part. Can be simplified. Also, according to the second embodiment, as in the case of the first embodiment, a process for manufacturing a multilayer ceramic substrate can be performed in a state of an aggregate substrate that is an aggregate of a plurality of ceramic laminates. .

  According to the third embodiment of the method for manufacturing a multilayer ceramic substrate according to the present invention, after obtaining an unfired ceramic laminate, an unfired side ceramic portion is imparted to the side surface of the unfired ceramic laminate. Thus, the multilayer ceramic substrate having the side ceramic portion can be manufactured without significantly changing the method for manufacturing the multilayer ceramic substrate having no side ceramic portion.

  1 to 3 are for explaining a first embodiment of the present invention. 1A is a cross-sectional view showing the multilayer ceramic substrate 11, and FIG. 1B is a cross-sectional view taken along line BB in FIG. 1A. 2 and 3 are for explaining a method of manufacturing the multilayer ceramic substrate 11 shown in FIG.

  Referring to FIG. 1, a multilayer ceramic substrate 11 has a multilayer structure comprising an inner layer ceramic portion 12 and two surface layer ceramic portions 13 and 14 positioned so as to sandwich the inner layer ceramic portion 12 in the stacking direction. 15 is provided. The inner layer ceramic part 12 is constituted by at least one inner layer part ceramic layer 16, and the surface layer ceramic parts 13 and 14 are constituted by at least one surface layer part ceramic layers 17 and 18, respectively.

  The multilayer ceramic substrate 11 preferably includes a conductor pattern mainly composed of silver or copper. The conductor pattern is provided in association with the inner layer ceramic portion 12 and / or the surface layer ceramic portions 13 and 14, and forms a passive element such as a capacitor or an inductor, or an electrical connection between the elements. It is for performing a simple connection wiring.

  As the conductor pattern, some internal conductor films 19 formed inside the ceramic laminate 15, some surface conductor films 12 formed on the outer surface of the first surface ceramic portion 13, and the ceramic laminate 15 A number of side surface electrodes 22 formed along side surfaces 21 extending in the stacking direction, and electrically connected to any one of the conductor films 19 and 20 and any one of the ceramic layers 16 to 18 in the thickness direction There are several via-hole conductors 23 provided so as to pass through.

  In FIG. 1A, a mother substrate 24 for mounting the multilayer ceramic substrate 11 is indicated by an imaginary line. The side electrode 22 described above is soldered and electrically connected to a conductive land on the mother substrate 24 side when mounted on the mother substrate 24.

  A surface-mounted electronic component 25 is mounted on the surface of the ceramic laminate 15 opposite to the mother substrate 24 when mounted, as indicated by a broken line. The surface mount electronic component 25 is electrically connected to a specific surface conductor film 20.

  In the ceramic laminate 15, the thermal expansion coefficients of the surface ceramic parts 13 and 14 are made smaller than the thermal expansion coefficient of the inner ceramic part 12. Thereby, high bending strength can be given to the ceramic laminate 15.

  As a characteristic configuration of the present invention, the ceramic laminate 15 is provided with a side ceramic portion 26 in a state along at least a part of the side surface 21 thereof. The side ceramic part 26 has a thermal expansion coefficient smaller than that of the inner ceramic part 12. The thermal expansion coefficient of the side ceramic part 26 is preferably substantially equal to the thermal expansion coefficient of the surface ceramic parts 13 and 14. The thermal expansion coefficient of the side ceramic part 26 is sufficient if it is smaller than the thermal expansion coefficient of the inner ceramic part 12, but in terms of the thermal expansion coefficient of the surface ceramic parts 13 and 14, if both are different, It is preferable that the coefficient of thermal expansion of the surface ceramic parts 13 and 14 is larger.

  The side surface ceramic portion 26 is provided in a state of being connected to at least one of the surface layer ceramic portions 13 and 14, but the side surface ceramic portion 26 is connected to the surface layer ceramic located on the mother substrate 24 side as in this embodiment. Part 14 is preferred. The presence of the side ceramic portion 26 improves the strength on the side surface 21 of the ceramic laminate 15, but as described above, when the surface layer ceramic portion 14 located on the mother substrate 24 side is connected to the side ceramic portion 26. In addition, the multilayer ceramic substrate 11 can be effectively protected from the damage caused by the impact or thermal stress that is easily applied when the multilayer ceramic substrate 11 is mounted on the mother substrate 24.

  The side ceramic part 26 is preferably provided so as to be in contact with at least a part of the peripheral edge part of the side electrode 22. In this embodiment, more preferably, the side ceramic part 26 is provided so as to be in contact with the entire periphery of the side electrode 22. Thereby, the strength in the vicinity of the side electrode 22 is improved, and the side electrode 22 can be made difficult to be peeled off even by an impact or thermal stress.

  As described above, the thermal expansion coefficient of the surface ceramic parts 13 and 14 and the thermal expansion coefficient of the side ceramic part 26 are made smaller than the thermal expansion coefficient of the inner ceramic part 12. In order to realize such a relationship in thermal expansion coefficient, as an example, the materials of the inner ceramic part 12, the surface ceramic parts 13 and 14, and the side ceramic part 26 are selected as follows.

The inner layer ceramic portion 12, the surface layer ceramic portions 13 and 14, and the side surface ceramic portion 26 are preferably made of a non-glass ceramic material. Non-glass based ceramic materials contain SiO ₂ based crystalline phases such as quartz and / or cristobalite, for example. In this case, the thermal expansion coefficient can be adjusted by changing the proportion of the SiO ₂ crystal phase. More specifically, the surface ceramic portions 13 and 14 and the side surface ceramic portion are reduced by reducing the surface ceramic portions 13 and 14 and the side surface ceramic portion 26 from the inner layer ceramic portion 12 with respect to the proportion of the SiO ₂ crystal phase. The thermal expansion coefficient of 26 can be made smaller than the thermal expansion coefficient of the inner layer ceramic portion 12.

The surface ceramic parts 13 and 14 and the side ceramic part 26 and the inner ceramic part 12 are preferably formed of materials having substantially the same composition except for the proportion of the SiO ₂ crystal phase. As a result, a good bonding state can be obtained between the surface ceramic parts 13 and 14 and the side ceramic part 26 and the inner ceramic part 12, and defects such as delamination are less likely to occur.

The surface ceramic parts 13 and 14 and the side ceramic part 26 and the inner ceramic part 12 are preferably formed of materials having substantially the same composition as described above. The “same composition” means a composition in which at least one (preferably two or more) same crystal phase can be precipitated in addition to the SiO ₂ crystal phase.

More specifically, the inner layer ceramic part 12, the surface layer ceramic parts 13 and 14, and the side surface ceramic part 26 are preferably formed of a BaO—Al ₂ O ₃ —SiO ₂ based low temperature sintered ceramic material. As a result, the bending strength of the inner layer ceramic portion 12, the surface layer ceramic portions 13 and 14 and the side surface ceramic portion 26 itself can be increased, and sintering at a relatively low temperature such as 950 to 1040 ° C. is possible in the firing process. It is. Therefore, when the conductor patterns such as the conductor films 19 and 20, the side electrode 22 and the via-hole conductor 23 described above are mainly composed of silver or copper, the firing of these conductor patterns is performed to obtain the ceramic laminate 15. Can be done at the same time. The BaO—Al ₂ O ₃ —SiO ₂ -based low-temperature sintered ceramic material is a typical non-glass-based material, but besides this, Al ₂ O ₃ —CaO—SiO ₂ —MgO—B ₂ O ₃ -based low-temperature sintering is also used. A sintered ceramic material (non-glass) can also be used.

The BaO—Al ₂ O ₃ —SiO ₂ -based low-temperature sintered ceramic material described above has a Ba of 4.0 to 50.0 wt% when converted to BaO, and an Al of 2.0 to 2.0 when converted to Al ₂ O _3. It is preferable to contain 60.0% by weight and 4.0 to 70.0% by weight of Si in terms of SiO ₂ .

When Ba is less than 4.0% by weight or more than 50.0% by weight in terms of BaO, the sinterability is deteriorated and the sintered body becomes difficult to be sufficiently densified, leading to a decrease in Q. . When Al is less than 2.0% by weight in terms of Al ₂ O ₃ , the Al compound that contributes to the improvement of the bending strength is not sufficiently precipitated, and the bending strength cannot be sufficiently increased. On the other hand, when Al exceeds 60.0% by weight in terms of Al ₂ O ₃ , the sinterability is deteriorated and the sintered body is not sufficiently densified, so that the bending strength may be lowered. When Si is less than 4.0% by weight or more than 70.0% by weight in terms of SiO ₂ , the sinterability deteriorates and the sintered body becomes difficult to be sufficiently densified, leading to a decrease in Q. is there. In addition, the BaO—Al ₂ O ₃ —SiO ₂ low-temperature sintered ceramic material having the composition system described above can precipitate a crystal phase of sambourite or celsian alumina in addition to the SiO ₂ crystal phase of quartz or cristobalite.

Note that the _BaO-Al 2 O 3 -SiO ₂ based low-temperature co-fired ceramic material, it is preferred that _B 2 _{O 3} in the range of 1 to 30 wt% is added. Thereby, the sinterability can be improved and the sintered body can be further densified.

The BaO—Al ₂ O ₃ —SiO ₂ low temperature sintered ceramic material (non-glass type) has been described above, but the ceramic material for the inner layer ceramic portion 12, the surface layer ceramic portions 13 and 14, and the side surface ceramic portion 26 is this. It is not limited to. For example, even a glass composite type or crystallized glass type low temperature sintered ceramic material can be suitably used as long as it has a SiO ₂ type crystal phase.

  In the multilayer ceramic substrate 11, it is preferable that the thickness of the inner layer ceramic portion 12 is 50 to 1500 μm, and the thickness of each of the surface layer ceramic portions 13 and 14 is 5 to 150 μm. The reason is as follows.

  Stress due to the difference in thermal expansion coefficient acts at the interface between the surface ceramic parts 13 and 14 and the inner ceramic part 12. More specifically, a compressive stress acts on the surface ceramic parts 13 and 14 side, and this compressive stress decreases as the distance from the interface increases. On the other hand, a tensile stress acts on the inner layer ceramic portion 12 side, and this tensile stress decreases as the distance from the interface increases. This is because the stress is relaxed according to the distance. If this distance exceeds 150 μm, compressive stress almost does not act on the surface and the effect is hardly seen. Therefore, the thickness of each of the surface ceramic portions 13 and 14 is preferably 150 μm or less.

  On the other hand, when the thickness of each of the surface layer ceramic portions 13 and 14 is less than 5 μm, the inner layer ceramic portion 12 whose strength is reduced due to the acting tensile stress exists in the region near the surface less than 5 μm from the surface. For this reason, breakage easily occurs from the inner layer ceramic portion 12 near the surface, and the effect strengthened by forming compressive stress in the surface layer ceramic portions 13 and 14 cannot be seen. Therefore, the thickness of each of the surface ceramic portions 13 and 14 is preferably 5 μm or more.

  The multilayer ceramic substrate 11 as described above is preferably manufactured as follows.

  In order to manufacture the multilayer ceramic substrate 11, an unfired aggregate substrate 32 that is an aggregate of a plurality of unfired ceramic laminates 31 as shown in FIG. 2 is produced. The unfired ceramic laminate 31 is to be fired to become the multilayer ceramic substrate 11, and when fired, the unfired inner layer ceramic that becomes the inner ceramic portion 12 in the multilayer ceramic substrate 11, respectively. Part 33, unfired surface ceramic parts 34 and 35 to be surface ceramic parts 13 and 14, and unfired side surface ceramic part 36 to be side ceramic part 26. The unfired ceramic laminate 31 includes the unfired ones of the internal conductor film 19, the surface conductor film 20, the side electrode 22, and the via-hole conductor 23.

  The collective substrate 32 is divided along a dividing line 37 indicated by a one-dot chain line in order to take out the plurality of ceramic laminated bodies 15 or the unfired ceramic laminated bodies 31 therefrom.

  The side electrode 22 described above is obtained by dividing the through-hole conductor formed in the collective substrate 32 along the dividing line 37.

The unfired inner layer ceramic portion 33, the unfired surface ceramic portions 34 and 35, and the unfired side surface ceramic portion 36 are, for example, raw materials for a BaO—Al ₂ O ₃ —SiO ₂ based low temperature sintered ceramic material. , At least SiO ₂ , and a material that generates a SiO ₂ -based crystal phase when fired. After firing, as described above, the ratio of the SiO ₂ crystal phase in the surface ceramic parts 13 and 14 and the side ceramic part 26 is made smaller than the ratio of the SiO ₂ crystal phase in the inner ceramic part 12. The compositions of the unfired surface ceramic parts 34 and 35, the side ceramic part 36 and the inner ceramic part 33 are selected.

In order to achieve the specific relationship as described above with respect to the proportion of the SiO ₂ based crystal phase, the first preferred embodiment includes the unfired surface ceramic parts 34 and 35 and the side ceramic part 36. the ratio of SiO ₂ to be is less than the proportion of SiO ₂ contained in the inner ceramic part 33 of the unfired. In the second preferred embodiment, the unfired surface ceramic portions 34 and 35 and the side surface ceramic portion 36 and the unfired inner layer ceramic portion 33 are formed of materials having substantially the same composition, and the unfired surface layer. The calcining temperature applied when the inorganic material contained in the ceramic parts 34 and 35 and the side ceramic part 36 is produced is calcined when the inorganic material contained in the unfired inner layer ceramic part 33 is produced. Higher than the temperature.

  The unfired inner layer ceramic portion 33 is configured with an inner layer ceramic green sheet 38 that becomes the inner layer ceramic layer 16 when fired, and the unfired surface layer ceramic portions 34 and 35 are respectively surface layer ceramic when fired. The surface layer ceramic green sheets 39 and 40 to be the layers 17 and 18 are formed. In order to produce the unfired collective substrate 32, the inner layer ceramic green sheet 38 and the surface layer ceramic green sheets 39 and 40 are usually prepared, laminated in a predetermined order, and then pressed. However, the unfired aggregate substrate 32 may be produced by forming a raw ceramic layer corresponding to each of the ceramic green sheets 38 to 40 by thick film printing.

  As shown in FIG. 2, an unfired side ceramic part 36 is formed in association with a specific one of the inner layer ceramic green sheets 38. In the embodiment shown in FIG. 2, in connection with the inner layer ceramic green sheet 38 (A) adjacent to the unfired surface ceramic portion 35 and the inner layer ceramic green sheet 38 (B) adjacent thereto, the unfired A side ceramic portion 36 is formed.

  FIG. 3 shows a state before the inner layer ceramic green sheet 38 (A) is stacked. Before lamination, the inner layer ceramic green sheet 38 (A) is provided with a through hole 41, and the through hole 41 is filled with a ceramic slurry to be the unfired side ceramic part 36. Next, a through-hole 42 is provided in the unfired side ceramic part 36, and the through-hole 42 is filled with a conductive paste to be the side electrode 22. The inner layer ceramic green sheet 38 (A) is further provided with a conductive paste to be the inner conductor film 19 and the via-hole conductor 23.

  In the other inner layer ceramic green sheets 38 and the surface layer ceramic green sheets 39 and 40 as well, as can be easily inferred from the above, the unfired side ceramic portions 36 should be formed in a predetermined form as necessary. Conductive paste to be ceramic slurry, conductor films 19 and 20, side electrode 22, and via-hole conductor 23 is applied.

Next, the unfired aggregate substrate 32 is fired. As an example, copper is used as the conductive component of the conductor films 19 and 20, the side electrode 22, and the via-hole conductor 23, and the unfired inner layer ceramic portion 33, the unfired surface layer ceramic portions 34 and 35, and the unfired side surface ceramic portion 36. Is a composition containing a raw material for a BaO—Al ₂ O ₃ —SiO ₂ -based low-temperature sintered ceramic material, it is fired at a temperature of 950 to 1040 ° C. in a reducing atmosphere. As a result of this firing, the aggregate substrate 32 is sintered.

  Next, the collective substrate 32 is divided along the dividing line 37, whereby the ceramic laminate 15 shown in FIG. 1 is obtained. The firing step described above may be performed after this dividing step.

It includes an inorganic material such as Al ₂ O ₃ that is not substantially sintered at a temperature at which the unfired inner layer ceramic portion 33, the unfired surface ceramic portions 34 and 35, and the unfired side surface ceramic portion 36 are sintered. A restraining green sheet may be prepared, and the firing step may be performed in a state where the restraining green sheet is disposed on at least one main surface of the unfired aggregate substrate 32 or the unfired ceramic laminate 31 after division. . In this case, the constraining green sheet does not substantially sinter in the firing step and thus does not shrink, and acts on the unfired ceramic laminate 31 to suppress shrinkage in the main surface direction. As a result, undesired deformation of the obtained ceramic laminate 15 after sintering can be suppressed and the dimensional accuracy can be improved, and at the time of firing, the unfired surface ceramic portions 34 and 35 and the unfired inner layer It is possible to make it difficult for the ceramic part 33 to peel off.

  FIG. 4 is a sectional view showing a multilayer ceramic substrate 11a according to the second embodiment of the present invention. FIG. 4 is a diagram corresponding to FIG. 1A. In FIG. 4, elements corresponding to those shown in FIG. 1A are denoted by the same reference numerals, and redundant description is omitted.

  The multilayer ceramic substrate 11a shown in FIG. 4 is characterized in that the side ceramic part 26 is provided along the entire side surface 21 of the ceramic laminate 15. Therefore, the side ceramic part 26 is in a state of being connected to both the two surface ceramic parts 13 and 14.

  According to such a multilayer ceramic substrate 11a, the strength at the side surface 21 can be made higher than that of the multilayer ceramic substrate 11 shown in FIG.

  FIGS. 5 and 6 are for explaining a third embodiment of the present invention. FIG. 5 is a sectional view showing the multilayer ceramic substrate 11b. FIG. 6 is a diagram showing the multilayer ceramic substrate 11b shown in FIG. It is sectional drawing for demonstrating this manufacturing method. 5 and 6, elements corresponding to the elements shown in FIGS. 1 to 3 described above are denoted by the same reference numerals, and redundant description is omitted. 5 and 6, illustration of the internal conductor film 19, the surface conductor film 20, the via-hole conductor 23, and the surface-mounted electronic component 25 shown in FIG. 1 and the like is omitted.

  Referring to FIG. 5, the ceramic laminate 15 provided in the multilayer ceramic substrate 11b is deformed at the bottom end portion. As a result, a part of the surface ceramic part 14 constitutes the side ceramic part 26. In this portion, a state in which the surface ceramic portion 14 is connected to the side ceramic portion 26 is obtained. A bottom conductor film 45 is formed, and a part of the bottom conductor film 45 constitutes the side electrode 22. And the side ceramic part 26 is located so that the peripheral part of this side electrode 22 may be touched.

  The multilayer ceramic substrate 11b as described above is preferably manufactured as follows.

  An unfired aggregate substrate 32 that is an aggregate of a plurality of unfired ceramic laminates 31 for the plurality of ceramic laminates 15 as shown in FIG. The unfired ceramic laminate 31 includes an unfired inner layer ceramic part 33 that becomes the inner layer ceramic part 12 when fired, and unfired surface layer ceramic parts 34 and 35 that become the surface layer ceramic parts 13 and 14 when fired. Has a laminated structure.

  The aggregate substrate 32 is divided along the dividing line 37, whereby the plurality of ceramic laminates 15 or the unfired ceramic laminate 31 are taken out. A bottom conductor film 45 is formed of a conductive paste on the aggregate substrate 32 so as to straddle the dividing lines 37.

  On the other hand, as shown in FIG. 6 (1), a press die 47 in which a protrusion 46 aligned so as to correspond to the position of the dividing line 37 is prepared.

  Next, as shown by arrows 48 and 49, the unfired aggregate substrate 32 and the press die 47 are brought close to each other. At this time, the protrusion 46 is pushed into the unfired surface ceramic part 35 from the outside. As a result, as shown in FIG. 6 (2), a part of the unfired surface ceramic part 35 at the dividing line 37 is deformed inward, and a part of the unfired surface ceramic part 35 is fired. As a result, an unfired side ceramic part 36 which becomes the side ceramic part 26 is formed.

  Along with the deformation of the unfired surface ceramic portion 35, the bottom conductor film 45 is also deformed, and the side electrode 22 is formed by a part of the bottom conductor film 45.

  Next, the unfired aggregate substrate 32 is fired. As a result, the aggregate substrate 32 is sintered.

  Next, the aggregate substrate 32 is divided along the dividing line 37, thereby obtaining the ceramic laminate 15 shown in FIG. 5. In this dividing step, the portion deformed inward of the surface ceramic portion 14 acts to facilitate the division. In addition, a baking process may be implemented after a division | segmentation process.

  7, 8, 9 and 10 are cross-sectional views showing multilayer ceramic substrates 11c, 11d, 11e and 11f according to the fourth, fifth, sixth and seventh embodiments of the present invention, respectively. 7 to 10, elements corresponding to those shown in FIG. 1A are denoted by the same reference numerals, and redundant description is omitted. 7 to 10, elements corresponding to the conductor films 19 and 20 and the via-hole conductor 23 shown in FIG. 1 are not shown.

  The multilayer ceramic substrate 11c shown in FIG. 7 is preferably manufactured as follows.

  First, an unsintered structure having a laminated structure in which an unsintered surface ceramic part that becomes the outer ceramic parts 13 and 14 when fired and an unfired inner layer ceramic part that becomes the inner ceramic part 12 when fired are laminated. A ceramic laminate is produced.

  Next, a ceramic slurry having a predetermined composition is applied to the entire side surface of the unfired ceramic laminate to provide an unfired side ceramic portion that becomes the side ceramic portion 26 when fired.

  Next, the unfired ceramic laminate provided with the unfired side ceramic portion is fired. Then, the side electrode 22 is formed by applying and baking a conductive paste so as to extend from the side surface to the bottom surface of the ceramic laminate 15.

  Next, in the multilayer ceramic substrate 11d shown in FIG. 8, the side surface ceramic portion 26 is formed along a part of the side surface 21 of the ceramic laminate 15 as compared with the multilayer ceramic substrate 11c shown in FIG. It is characterized by that.

  Next, the multilayer ceramic substrate 11e shown in FIG. 9 is characterized in that a bottom surface conductor film 52 is formed instead of the side electrode 22 as compared with the multilayer ceramic substrate 11c shown in FIG. When the multilayer ceramic substrate 11e is mounted on the mother substrate, the bottom conductor film 52 is electrically connected to the conductive land on the mother substrate side.

  Next, the multilayer ceramic substrate 11 f shown in FIG. 10 is characterized by including a cavity 55. The cavity 55 has an opening directed toward the mother substrate 24 on which the multilayer ceramic substrate 11c is mounted. A bottom conductor film 57 is formed on the bank 56 around the cavity 55, and the bottom conductor film 57 is electrically connected to the conductive land on the mother substrate 24 side.

  In such a multilayer ceramic substrate 11 f, the side ceramic part 26 is provided in a state of being connected to the surface ceramic part 14. In FIG. 10, the side ceramic portion 26 is provided only on the bank portion 56, but may be further provided so as to be connected to the surface ceramic portion 13 on the upper surface side.

  The side ceramic portion 26 shown in FIG. 10 is provided by a method substantially similar to the method described with reference to FIG. 2, but is substantially the same as the method described with reference to FIG. It may be provided by a method or a method substantially similar to the method described with reference to FIG.

1 shows a multilayer ceramic substrate 11 according to a first embodiment of the present invention, in which (a) is a sectional view taken from the front direction, and (b) is a sectional view taken along line BB in (a). . FIG. 2 is a cross-sectional view showing an unfired collective substrate 32 produced in the middle of manufacturing the multilayer ceramic substrate 11 shown in FIG. 1. It is sectional drawing which shows independently the state before lamination | stacking of the inner-layer part ceramic green sheet 38 (A) shown in FIG. It is sectional drawing which shows the multilayer ceramic substrate 11a by 2nd Embodiment of this invention. It is sectional drawing which shows the multilayer ceramic substrate 11b by 3rd Embodiment of this invention. FIG. 6 is a cross-sectional view showing an unfired aggregate substrate 32 for explaining a method of manufacturing the multilayer ceramic substrate 11b shown in FIG. It is sectional drawing which shows the multilayer ceramic substrate 11c by 4th Embodiment of this invention. It is sectional drawing which shows the multilayer ceramic substrate 11d by 5th Embodiment of this invention. It is sectional drawing which shows the multilayer ceramic substrate 11e by 6th Embodiment of this invention. It is sectional drawing which shows the multilayer ceramic substrate 11f by 7th Embodiment of this invention. It is sectional drawing which shows the conventional multilayer ceramic substrate 1 interesting for this invention.

Explanation of symbols

11, 11a to 11f Multilayer ceramic substrate 12 Inner layer ceramic part 13, 14 Surface layer ceramic part 15 Ceramic laminate,
DESCRIPTION OF SYMBOLS 21 Side surface 22 Side surface electrode 24 Mother board 25 Surface mount type electronic component 26 Side surface ceramic part 31 Unbaked ceramic laminated body 32 Collective substrate 33 Unfired inner layer ceramic part 34,35 Unfired surface layer ceramic part 36 Unfired side surface ceramic Part 37 Dividing line 46 Projection

Claims (9)

  A ceramic laminated body having a laminated structure in which an inner layer ceramic part having a second thermal expansion coefficient larger than the first thermal expansion coefficient is sandwiched between two surface ceramic parts having a first thermal expansion coefficient And having a third thermal expansion coefficient smaller than the second thermal expansion coefficient along at least a part of a side surface extending in the stacking direction of the ceramic laminate and connected to at least one of the surface ceramic layers. A multilayer ceramic substrate provided with a side ceramic part.   2. The multilayer ceramic substrate according to claim 1, wherein the third thermal expansion coefficient is substantially equal to or greater than the first thermal expansion coefficient.   3. The multilayer ceramic substrate according to claim 1, wherein, of the two surface layer ceramic portions, only the surface layer ceramic portion located on the mother substrate side in mounting is connected to the side surface ceramic portion.   The side ceramic part is further provided with the side electrode formed along the side surface of the said ceramic laminated body, The said side ceramic part is provided so that at least one part of the peripheral part of the said side electrode may be contact | connected. A multilayer ceramic substrate as described in 1.   The surface layer ceramic part, the inner layer ceramic part, and the side surface ceramic part are made of a low-temperature sintered ceramic, and are provided in association with the surface layer ceramic part and / or the inner layer ceramic part and contain silver or copper as a main component. The multilayer ceramic substrate according to any one of claims 1 to 4, further comprising a conductor pattern.   The multilayer ceramic substrate according to any one of claims 1 to 5, further comprising a surface-mounted electronic component that is mounted on a surface opposite to the mother substrate when the ceramic laminate is mounted. A ceramic laminated body having a laminated structure in which an inner layer ceramic part having a second thermal expansion coefficient larger than the first thermal expansion coefficient is sandwiched between two surface ceramic parts having a first thermal expansion coefficient And a side ceramic part having a third thermal expansion coefficient smaller than the second thermal expansion coefficient along at least a part of a side surface extending in the stacking direction of the ceramic laminate and connected to the surface ceramic part A method for producing a multilayer ceramic substrate, comprising:
It has a laminated structure in which an unfired surface layer ceramic part that becomes the surface layer ceramic part when fired and an unfired inner layer ceramic part that becomes the inner layer ceramic part when fired, and the side surface when fired A step of producing an unfired aggregate substrate, which is an aggregate of a plurality of unfired ceramic laminates, having an unfired side ceramic part to be a ceramic part in a part thereof;
Firing the unfired aggregate substrate;
Dividing the aggregate substrate so that the side ceramic portion is exposed on the side surface. A ceramic laminated body having a laminated structure in which an inner layer ceramic part having a second thermal expansion coefficient larger than the first thermal expansion coefficient is sandwiched between two surface ceramic parts having a first thermal expansion coefficient And a side ceramic part having a third thermal expansion coefficient smaller than the second thermal expansion coefficient along at least a part of a side surface extending in the stacking direction of the ceramic laminate and connected to the surface ceramic part A method for producing a multilayer ceramic substrate, comprising:
An unfired ceramic laminate having a laminated structure in which an unfired surface ceramic part that becomes the surface ceramic part when fired and an unfired inner ceramic part that becomes the inner ceramic part when fired are laminated A manufacturing process;
A part of the unfired surface ceramic part was deformed inward by pushing protrusions from outside into the unfired surface layer ceramic part, and was fired with a part of the unfired surface layer ceramic part. Sometimes forming an unfired side ceramic part to be the side ceramic part;
And a step of firing the unfired ceramic laminate. A ceramic laminated body having a laminated structure in which an inner layer ceramic part having a second thermal expansion coefficient larger than the first thermal expansion coefficient is sandwiched between two surface ceramic parts having a first thermal expansion coefficient And a side ceramic part having a third thermal expansion coefficient smaller than the second thermal expansion coefficient along at least a part of a side surface extending in the stacking direction of the ceramic laminate and connected to the surface ceramic part A method for producing a multilayer ceramic substrate, comprising:
An unfired ceramic laminate having a laminated structure in which an unfired surface ceramic part that becomes the surface ceramic part when fired and an unfired inner ceramic part that becomes the inner ceramic part when fired are laminated A manufacturing process;
Providing at least a part of the side surface of the unfired ceramic laminate with an unfired side surface ceramic portion that becomes the side surface ceramic portion when fired;
And a step of firing the unfired ceramic laminate provided with the unfired side ceramic portion.

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