JP4284782B2 - Multilayer ceramic substrate and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a multilayer ceramic substrate that can substantially prevent shrinkage in a planar direction in a firing step for obtaining a multilayer ceramic substrate, and is particularly obtained in the firing step. The present invention relates to a method for manufacturing a multilayer ceramic substrate and a multilayer ceramic substrate manufactured by this method, which are improved to form protrusions that can function as bump electrodes, spacers, etc. on the main surface of the multilayer ceramic substrate. .
[0002]
[Prior art]
In order to increase the functionality, density, and performance of a multilayer ceramic substrate, it is effective to provide wiring at a high density in such a multilayer ceramic substrate.
[0003]
However, the firing process for obtaining a multilayer ceramic substrate involves shrinkage of the multilayer ceramic substrate and it is difficult to avoid such variations in shrinkage. This is a factor that hinders the high density of wiring on the substrate.
[0004]
Under such a background, a so-called non-shrinking process has been proposed that can suppress shrinkage in a planar direction in a firing step for obtaining a multilayer ceramic substrate.
[0005]
In the non-shrink process, a plurality of substrate green sheets containing a ceramic material are prepared, and a shrinkage-suppressing green sheet containing a ceramic that is not sintered at the firing temperature of the substrate green sheet is prepared. For example, a composite laminate in which a green sheet for suppressing shrinkage is disposed so as to sandwich a raw laminate for a substrate obtained by laminating a substrate is produced, and a firing process is applied to the composite laminate.
[0006]
In this firing step, only the substrate laminate is sintered so that the substrate laminate is a multilayer ceramic substrate, and the shrinkage suppressing green sheet exists as a shrinkage suppressing support in an unsintered state, By applying a force that suppresses shrinkage, that is, a restraining force, to the substrate laminate, shrinkage in the planar direction of the substrate laminate is suppressed. The substrate laminate shrinks in the thickness direction in this firing step.
[0007]
As described above, according to the non-shrinkage process, it is difficult to cause shrinkage in the planar direction of the laminate for a substrate, so that the dimensional accuracy in the planar direction of the obtained multilayer ceramic substrate can be increased. It is possible to advantageously increase the density of the wiring in.
[0008]
[Problems to be solved by the invention]
By the way, the multilayer ceramic substrate as described above is used, for example, as a package or module substrate on which an IC is mounted. Recently, however, it has been applied to a multichip module (MCM) substrate on which a plurality of ICs are mounted. ing.
[0009]
In multilayer ceramic substrates intended for such applications, the number of input / output terminals for achieving electrical connection by mounting on a motherboard has increased dramatically with the increase in wiring density. For this reason, a ball grid array (BGA) type in which input / output pads arranged two-dimensionally on a substrate surface are connected by solder balls has become the mainstream as a connection form adopted in the input / output terminals.
[0010]
In such a BGA type multi-layer ceramic substrate, the input / output terminals are connected mainly by solder bumps. In general, on the land offset from the via hole filled with the conductor for the input / output terminals. Bumps are formed on.
[0011]
However, as the mounting density increases, not only the offset described above but also the land formation on the via hole becomes difficult. In addition, since a relatively large amount of solder is used in the solder bumps, for example, if the bump connection is made directly to the via hole conductor, the stress tends to concentrate on each interface portion between the via hole conductor, the solder bump, and the substrate. Defects such as cracks are likely to occur in the solder or the substrate.
[0012]
On the other hand, there is also a method of connecting directly via a thin solder film without forming bumps on the lands.
[0013]
However, the surface of the conductor filled in the via hole and the surface of the substrate are often not on the same plane. For example, if the surface of the via hole conductor is lower than the surface of the substrate, an open defect is likely to occur in connection. . Further, it is necessary to manage the substrate warpage and waviness with high accuracy so that this does not occur. In order to improve the flatness of the substrate, post-processing such as grinding and polishing is effective. However, it is necessary to process the entire surface of the substrate, and the cost for that is increased, so that it is not practical. I can't say that.
[0014]
Accordingly, an object of the present invention is to provide a method for producing a multilayer ceramic substrate effective for solving the above-described problems and a multilayer ceramic substrate obtained by this production method.
[0015]
[Means for Solving the Problems]
The present invention is first directed to a method of manufacturing a multilayer ceramic substrate comprising a plurality of laminated ceramic layers and wiring conductors made of a ceramic material. In this manufacturing method, the following steps are performed.
[0016]
A plurality of substrate green sheets containing a ceramic material are prepared, and a plurality of shrinkage suppressing green sheets containing a ceramic that is not sintered at the firing temperature of the substrate green sheet.
[0017]
A wiring conductor is formed in a specific green sheet for a substrate, and a hole is provided in a specific green sheet for shrinkage suppression.
[0018]
Next, a plurality of green sheets for a substrate are laminated, forming a wiring conductor, a raw substrate laminate to be a multilayer ceramic substrate, and each main surface of the raw substrate laminate A composite laminate including the shrinkage-suppressing green sheets that are laminated to each other is produced. In this composite laminate, a cavity having an open end closed by at least one main surface of the raw substrate laminate is formed by a hole provided in the shrinkage-suppressing green sheet.
[0019]
Next, the composite laminate described above is fired. In this firing step, the laminate for substrate is sintered in order to obtain a multilayer ceramic substrate, but the shrinkage-suppressing green sheet is present as a shrinkage-suppressing support in an unsintered state, and the shrinkage-suppressing support is used. A restraint force is applied to the substrate laminate so that the substrate laminate is substantially contracted only in the thickness direction while suppressing shrinkage in the plane direction of the substrate laminate. The portion is raised along the inner surface of the cavity described above.
[0020]
Next, the above-described shrinkage suppression support is removed.
[0021]
In the method for manufacturing a multilayer ceramic substrate according to the present invention, the aforementioned cavity may form a bottomed recess or a through hole.
[0022]
Further, in the method for manufacturing a multilayer ceramic substrate according to the present invention, when the wiring conductor includes a via-hole conductor, the portion of the main surface of the raw substrate laminate that closes the open end of the cavity One end of the via-hole conductor may be positioned.
[0023]
In the method for manufacturing a multilayer ceramic substrate according to the present invention, the open end of the cavity may have a spot shape or a longitudinal shape.
[0024]
In the method for manufacturing a multilayer ceramic substrate according to the present invention, the wiring conductor is selected from the group consisting of Ag, Ag—Pt alloy, Ag—Pd alloy, Cu, Ni, Pt, Pd, W, Mo, and Au. It is preferable to use at least one kind as a main component.
[0025]
In the method for producing a multilayer ceramic substrate according to the present invention, the step of firing the composite laminate is preferably performed at a temperature of 1000 ° C. or lower.
[0026]
In the case described above, it is preferable that the shrinkage-suppressing green sheet contains at least one selected from alumina, zirconia and magnesia.
[0027]
Further, in the method for producing a multilayer ceramic substrate according to the present invention, when the composite laminate is fired, 10 kg / cm in the lamination direction.²It is preferable to apply the following loads.
[0028]
  The present invention is also directed to a multilayer ceramic substrate manufactured by the manufacturing method as described above..
[0033]
DETAILED DESCRIPTION OF THE INVENTION
1 to 5 are diagrams for explaining an embodiment of the present invention. Here, FIG. 4 shows a cross-sectional view of the multilayer ceramic substrate 1 according to this embodiment, and FIGS. 1 to 3 sequentially show the steps performed for manufacturing the multilayer ceramic substrate 1. FIG. 5 shows an example of the use of the multilayer ceramic substrate 1.
[0034]
First, the structure of the multilayer ceramic substrate 1 will be described with reference to FIG.
[0035]
The multilayer ceramic substrate 1 includes a plurality of laminated ceramic layers 2 made of a ceramic material and various wiring conductors. As the wiring conductor, internal conductors 3, 4,... Formed along a specific interface between the ceramic layers 2, and via-hole conductors 5, 6,... Extending through in the thickness direction of the specific ceramic layer 2 are used. I have. Further, connection electrodes 8, 9, 10, 11, 12, 13,... Are formed on one main surface 7 of the multilayer ceramic substrate 1.
[0036]
Further, on the other main surface 14 of the multilayer ceramic substrate 1, protrusions 15, 16,... Made of a ceramic material constituting the ceramic layer 2 are formed integrally with the ceramic layer 2. One end of each of the via-hole conductors 5 and 6 is located at the top of each of the illustrated protrusions 15 and 16.
[0037]
As described above, the protrusions 15 and 16 exposing the via-hole conductors 5 and 6 can function as bump electrodes.
[0038]
In FIG. 5, the multilayer ceramic substrate 1 is shown in an upside down posture from the posture shown in FIG. As shown in FIG. 5, an IC chip 17 is mounted on the main surface 7 of the multilayer ceramic substrate 1 so as to be connected to the connection electrodes 8 and 9 and is connected to the connection electrodes 10 and 11. A chip capacitor 18 is mounted, and a thick film resistor 19 is formed so as to be connected to the connection electrodes 12 and 13.
[0039]
In this way, the multilayer ceramic substrate 1 constitutes a functional module and is mounted on the mother board 20 constituted by, for example, a printed circuit board.
[0040]
Conductive lands 22 and 23 are formed on one main surface 21 of the motherboard 20 corresponding to the positions of the protrusions 15 and 16 of the multilayer ceramic substrate 1. As shown in FIG. 5, in a state where the protrusions 15 and 16 are aligned with the conductive lands 22 and 23, respectively, solder (such as to electrically connect the via-hole conductors 5 and 6 and the conductive lands 22 and 23 to each other) Is omitted). Thereby, the mounting of the multilayer ceramic substrate 1 on the mother board 20 is completed.
[0041]
A method for manufacturing such a multilayer ceramic substrate 1 will be described with reference to FIGS.
[0042]
First, referring to FIG. 1, a plurality of green sheets 24 for a substrate including a ceramic material to be the ceramic layer 2 is prepared. The substrate green sheet 24 can be produced, for example, by preparing a slurry by dispersing a mixed powder composed of alumina powder and borosilicate glass in an organic vehicle, and forming the slurry into a sheet by a casting method.
[0043]
The substrate green sheet 24 is preferably sinterable at a temperature of 1000 ° C. or lower, and therefore contains a glass having a softening point of 800 ° C. or lower in the ceramic component as an insulating material, magnetic material, or dielectric material. It is preferable to do. In this case, the weight ratio of glass component / ceramic component is preferably selected within the range of 100/0 to 5/95.
[0044]
Moreover, it is preferable that the ceramic material contained in the substrate green sheet 24 contains a liquid phase formation product that generates a liquid phase at a temperature of 900 ° C. or lower. In this case, the content of the liquid phase forming product is preferably selected within a range of 5 to 100% by weight with respect to the entire ceramic material.
[0045]
The internal conductors 3, 4,... And the via-hole conductors 5, 6,. These wiring conductors are mainly composed of at least one selected from the group consisting of Ag, Ag—Pt alloy, Ag—Pd alloy, Cu, Ni, Pt, Pd, W, Mo, and Au. It can be formed by applying a conductive paste containing a metal as a conductive component. Of the metals described above, Ag, Ag—Pt alloy, Ag—Pd alloy, and Cu are particularly suitable for use in the wiring conductor because of their low specific resistance.
[0046]
Further, a plurality of shrinkage-suppressing green sheets 25 and 26 containing ceramics that are not sintered at the firing temperature of the above-described substrate green sheet 24 are prepared. These shrinkage-suppressing green sheets 25 and 26 can be obtained, for example, by preparing a slurry by dispersing alumina powder in an organic vehicle and molding the slurry into a sheet by a casting method. The sintering temperature of the green sheets 25 and 26 for shrinkage suppression thus obtained is 1500 to 1600 ° C.
[0047]
In place of or in addition to the above-mentioned alumina powder, ceramic powder such as zirconia or magnesia can also be used. The shrinkage-suppressing green sheets 25 and 26 preferably contain the same ceramic component as that contained in the substrate green sheet 24 described above.
[0048]
A specific one of the shrinkage suppressing green sheets 25 and 26, that is, the shrinkage suppressing green sheet 25 is provided with holes 27, 28,. The holes 27 and 28 are provided at positions corresponding to the positions of the via-hole conductors 5 and 6 formed in the substrate green sheet 24, respectively.
[0049]
Next, the substrate green sheet 24 and the shrinkage suppressing green sheets 25 and 26 are stacked in the order shown in FIG. 1 to produce a composite laminate 29 as shown in FIG.
[0050]
More specifically, the composite laminate 29 includes a raw substrate laminate 30 formed by laminating a plurality of substrate green sheets 24. The substrate laminate 30 is to be the multilayer ceramic substrate 1 shown in FIG. 4, and forms the internal conductors 3, 4,... And the via-hole conductors 5, 6,.
[0051]
A plurality of shrinkage-suppressing green sheets 25 provided with holes 27 and 28 are stacked on one main surface 31 of the raw substrate laminate 30 described above, and holes are formed on the other main surface 32. A plurality of shrinkage-suppressing green sheets 26 that are not provided are stacked.
[0052]
When attention is paid to the main surface 31 side of the substrate laminate 30, the holes 27 and 28 provided in the shrinking green sheet 25 form a series of cavities 33 and 34, respectively. The open ends 35 and 36 of the cavities 33 and 34 are closed by the main surface 31 of the substrate laminate 30. Then, one end of each of the via-hole conductors 5 and 6 is positioned in a portion of the main surface 31 of the substrate laminate 30 where the open ends 35 and 36 of the cavities 33 and 34 are closed.
[0053]
The composite laminate 29 shown in FIG. 2 is then pressed in the lamination direction. For this press, for example, 200 to 1000 kg / cm²The hydraulic press is applied. Although not shown in FIG. 2, as a result of this pressing, a part of the substrate laminate 30 may rise slightly in the portion where the open ends 35 and 36 of the cavities 33 and 34 are closed.
[0054]
Next, the composite laminate 29 is fired at a temperature of 1000 ° C. or lower, for example. In this firing step, 10 kg / cm in the stacking direction²It is preferable to apply the following loads.
[0055]
As a result of the above-mentioned firing, as shown in FIG. 3, the multilayer body for substrate 30 is sintered, and the multilayer ceramic substrate 1 is obtained. Further, the shrinkage-suppressing green sheets 25 and 26 exist as shrinkage-suppressing supports 37 and 38 in an unsintered state. More specifically, the shrinkage-suppressing supports 37 and 38 are in an alumina porous state in which the organic binder contained in the shrinkage-suppressing green sheets 25 and 26 is scattered.
[0056]
In the firing step as described above, the shrinkage-suppressing supports 37 and 38 maintain an unsintered state, so that the restraining force thereby exerts on the laminate 30 for the substrate to be sintered, While suppressing the shrinkage of the substrate laminate 30 in the planar direction, the substrate laminate 30 acts to substantially shrink only in the thickness direction. As a result, in the portion where the open ends 35 and 36 of the cavities 33 and 34 are closed, a part of the laminated body 30 for the substrate rises along the inner surfaces of the cavities 33 and 34 and is sintered. , The projections 15 and 16 are formed.
[0057]
In a specific example, it has been confirmed that the thickness of the multilayer ceramic substrate 1 after sintering is approximately 0.6 times the thickness of the substrate laminate 30 before sintering. Further, the total thickness of the plurality of shrinkage suppression green sheets 25 and the total thickness of the plurality of shrinkage suppression green sheets 26 are about 0.8 to 1.0 mm, and the thickness of the raw substrate laminate 30 is about 1.2 mm. However, when the cross-sectional shape of each of the holes 27 and 28 is circular and the diameter thereof is 2 mm, it is confirmed that the formed protrusions 15 and 16 have a height of several hundred μm and a diameter of about 2 mm.
[0058]
The heights of the protrusions 15 and 16 vary depending on the constituent material and thickness of the substrate laminate 30, the pressure applied during pressing, the firing conditions, the dimensions of the holes 27 and 28, etc., but these parameters are adjusted. By doing so, the dimensions of the protrusions 15 and 16 can be variously changed.
[0059]
Next, by removing the shrinkage suppression supports 37 and 38, the multilayer ceramic substrate 1 is taken out as shown in FIG. For this removal, a wet honing method, a sand blast method, an ultrasonic vibration method, or the like is applied, and the shrinkage suppression supports 37 and 38 are removed while being peeled off, for example.
[0060]
Thereafter, the above-described connection electrodes 8 to 13 are formed on the main surface 7 of the multilayer ceramic substrate 1, and the IC chip 17, the chip capacitor 18, the thick film resistor 19 and the like are mounted, thereby functioning as a functional module. The multilayer ceramic substrate 1 is completed.
[0061]
According to the multilayer ceramic substrate 1 obtained in this way, the protrusions 15 and 16 have bump electrodes provided at the tops of the via hole conductors 5 and 6, respectively. 5 and 16 can be mounted on the mother board 20 without any problem as shown in FIG. 5, even if the main surface 14 has some irregularities.
[0062]
If the heights of the protrusions 15 and 16 are not uniform, the heights can be uniformed by polishing, for example, and a process for eliminating the irregularities on the main surface 14 of the multilayer ceramic substrate 1 is performed. Compared to the case, the processing for aligning the heights of the protrusions 15 and 16 is so easy as not to be compared.
[0063]
Since the via-hole conductors 5 and 6 are reinforced by the protrusions 15 and 16 made of ceramic, the mechanical strength of the bump electrode is high, and therefore, the handling of the multilayer ceramic substrate 1 is good. It can be.
[0064]
FIGS. 6 and 7 are diagrams corresponding to FIGS. 2 and 3 for describing another embodiment of the present invention, respectively. 6 and 7, elements corresponding to those shown in FIGS. 2 and 3 are denoted by the same reference numerals, and redundant description is omitted.
[0065]
In the embodiment described with reference to FIGS. 2 and 3, the cavities 33 and 34 have formed through holes. In this embodiment, however, the cavities 33 a and 34 a have a bottomed recess. It is a feature.
[0066]
Therefore, as shown in FIG. 6, on the main surface 31 side of the substrate laminate 30, the shrinkage suppressing green sheets 25 provided with the holes 27 and 28 are stacked so as to be in contact with the main surface 31. On top, a shrinkage-suppressing green sheet 26 without holes is laminated.
[0067]
Therefore, as shown in FIG. 7, when the firing process of the composite laminate 29a is finished, the protrusions 15a and 16a are formed not only on the inner peripheral surfaces of the cavities 33a and 34a but also on the upper end surface. Can do. From this, it becomes possible to set the heights of the protrusions 15a and 16a more strictly.
[0068]
FIG. 8 is a sectional view schematically showing a multilayer ceramic substrate 39 manufactured according to another embodiment of the present invention. Although not shown, the multilayer ceramic substrate 39 includes a plurality of laminated ceramic layers and wiring conductors made of a ceramic material.
[0069]
On one main surface 40 of the multilayer ceramic substrate 39, connection electrodes 41 and 42 and protrusions 43 and 44 are formed. These protrusions 43 and 44 are formed by the same method as the protrusions 15 and 16 described above.
[0070]
Further, on the main surface 40 side of the multilayer ceramic substrate 39, an electronic component 45 such as an IC chip is soldered to the connection electrodes 41 and 42 and the distance between the main surface 40 is defined by the projections 43 and 44. Has been implemented.
[0071]
The multilayer ceramic substrate 39 has a plurality of terminal electrodes 48 formed of solder bumps on the other main surface 47.
[0072]
As described above, when the electronic component 45 is mounted on the multilayer ceramic substrate 39, the reflow is applied with the solder 46 formed on the electronic component 45 side and in contact with the connection electrodes 41 and 42. . At this time, since the solder 46 is generally soft, deformation such as crushing occurs and connection failure is likely to occur. Therefore, delicate control of the amount of the solder 46 and the force applied to the electronic component 45 at the time of mounting is necessary. It is. On the other hand, according to this embodiment, since the protrusions 43 and 44 function as spacers, such delicate control of the amount of solder 46 and the force applied during mounting is unnecessary, and therefore, a process for mounting The work efficiency can be improved.
[0073]
The protrusions 43 and 44 shown in FIG. 8 can also be applied as spacers when mounted on the mother board 20 as shown in FIG.
[0074]
FIG. 9 is a sectional view schematically showing a multilayer ceramic substrate 49 manufactured according to still another embodiment of the present invention. The multilayer ceramic substrate 49 also includes a plurality of laminated ceramic layers and wiring conductors made of a ceramic material, although not shown.
[0075]
On one main surface 50 of the multilayer ceramic substrate 49, two rib-shaped protrusions 51 and 52 made of a ceramic material are formed at intervals. These protrusions 51 and 52 are formed by the same method as the protrusions 15 and 16 described above.
[0076]
Several electronic components 53 are mounted on the main surface 50 side where the protrusions 51 and 52 are formed, and a cap 54 is disposed so as to cover these electronic components 53. The cap 54 is fixed by the resin 55 while the lower end edge thereof is positioned between the two rib-shaped protrusions 51 and 52. The cap 54 performs a shielding function.
[0077]
In this embodiment, the protrusions 51 and 52 function as dams that prevent the flow of the resin 55 applied by potting.
[0078]
Such protrusions 51 and 52 can also function as dams for preventing the solder from flowing out.
[0079]
FIG. 10 is a cross-sectional view schematically showing a multilayer ceramic substrate 56 manufactured according to still another embodiment of the present invention. The multilayer ceramic substrate 56 also includes a plurality of laminated ceramic layers and wiring conductors made of a ceramic material, although not shown.
[0080]
On one main surface 57 of the multilayer ceramic substrate 56, an enclosed wall-shaped protrusion 58 made of a ceramic material is formed. The protrusion 58 is also formed by the same method as the protrusions 15 and 16 described above.
[0081]
Several electronic components 59 are mounted in the region surrounded by the protrusions 58 on the main surface 57 side where the protrusions 58 are formed. The lid 60 is disposed so as to close the space surrounded by the wall-shaped protrusions 58. The lid 60 performs, for example, a shielding function, but may also be a circuit module configuration such as a temperature compensated crystal oscillator (TCXO).
[0082]
Although the present invention has been described above with reference to some illustrated embodiments, various other modifications are possible within the scope of the present invention.
[0083]
For example, the design of the wiring conductor in the multilayer ceramic substrate 1 shown in FIG. 4 is merely an example, and other various circuit designs can be employed in the multilayer ceramic substrate. In addition, passive components such as capacitors, inductors, and resistors may be incorporated in the multilayer ceramic substrate. In this case, it is desirable that the capacitor and the inductor be block-shaped parts.
[0084]
Also, protrusions may be formed on the lower main surface 7 of the multilayer ceramic substrate 1 in FIG. 4 by the same method as the protrusions 15 and 16. This protrusion can be used as a spacer when mounting an electronic component, for example, like the protrusions 43 and 44 shown in FIG.
[0085]
【The invention's effect】
As described above, according to the method for manufacturing a multilayer ceramic substrate according to the present invention, a raw substrate which is formed by laminating a plurality of substrate green sheets and which forms a wiring conductor and is to be a multilayer ceramic substrate A composite laminate comprising a laminate for use and a shrinkage-suppressing green sheet that is laminated on each main surface of the raw substrate laminate, and then shrinking by firing the composite laminate While the suppression green sheet is present as a support for suppressing shrinkage in an unsintered state, the multilayer body for the substrate is obtained by sintering the multilayer body for the substrate. Since shrinkage is suppressed and variation in shrinkage is also reduced, it is possible to increase the dimensional accuracy of the obtained multilayer ceramic substrate and to increase the density of wiring by the wiring conductor. Kill.
[0086]
Further, in the above-described composite laminate subjected to the firing step, a cavity having an open end closed by at least one main surface of the raw substrate laminate is formed by a hole provided in the shrinkage-suppressing green sheet. ing. Therefore, in the firing step, the substrate laminate is substantially only in the thickness direction while restraining the shrinkage in the plane direction of the substrate laminate by causing the restraint force by the shrinkage suppression support to act on the substrate laminate. Therefore, a part of the laminated body for the substrate is raised along the inner surface of the cavity, whereby the protrusion can be easily formed.
[0087]
The shape of the protrusion depends on the shape of the opening end of the cavity. For example, when the opening end of the cavity has a spot shape, a protrusion protruding in a spot shape is formed, and the opening end of the cavity has a longitudinal shape. In this case, a protrusion extending in the longitudinal direction can be formed.
[0088]
Further, in the composite laminate described above, when one end of the via-hole conductor is located in a portion of the main surface of the raw substrate laminate that closes the open end of the cavity, the via-hole conductor is formed on the top of the protrusion. One end of the projection can be positioned, and such a projection can function as a bump electrode. In this case, according to the present invention, since a large number of protrusions can be formed in a relatively small area, the distribution density of the bump electrodes can be increased, and the wiring density of the multilayer ceramic substrate can be increased. Can do. In addition, it is easy to make the heights of the projections to be bump electrodes uniform, and therefore it is possible to make it difficult to cause open defects in the electrical connection.
[0089]
Further, according to the present invention, in addition to the protrusions functioning as bump electrodes as described above, the protrusions functioning as spacers for achieving proper soldering with electronic components mounted on the multilayer ceramic substrate, , Including a rib-like protrusion for positioning the lower end edge of the cap and preventing the resin from flowing out for fixing the cap, a wall-like protrusion for defining a closed space where the lid is disposed, and the like. A multilayer ceramic substrate can be easily manufactured.
[0090]
Further, in the step of firing the composite laminate provided for the method for producing a multilayer ceramic substrate according to the present invention, if a load of 10 kg / cm or less is applied in the laminating direction, the obtained multilayer ceramic substrate is warped or waved. Undesirable deformation of the substrate can be advantageously prevented, and a part of the substrate laminate for the formation of protrusions can be more reliably raised.
[0091]
In addition, if the cavity that causes the swell in the inside forms a bottomed recess, the height of the protrusion can be controlled more strictly.
[Brief description of the drawings]
FIG. 1 shows a plurality of substrate green sheets 24 and a plurality of shrinkage suppression green sheets 25 and 26 prepared in the method for manufacturing a multilayer ceramic substrate according to an embodiment of the present invention, arranged in accordance with the stacking order thereof. It is sectional drawing.
2 is a cross-sectional view showing a composite laminate 29 obtained by laminating the substrate green sheet 24 and the shrinkage suppressing green sheets 25 and 26 shown in FIG.
FIG. 3 is a cross-sectional view showing a state after firing the composite laminate 29 shown in FIG.
4 is a cross-sectional view showing a multilayer ceramic substrate 1 obtained by removing the shrinkage suppression supports 37 and 38 shown in FIG. 3. FIG.
5 is a cross-sectional view showing a state in which the multilayer ceramic substrate 1 shown in FIG. 4 is mounted on a mother board 20. FIG.
6 is a view corresponding to FIG. 2 for explaining another embodiment of the present invention, and is a cross-sectional view showing a composite laminate 29a. FIG.
7 is a cross-sectional view corresponding to FIG. 3, showing a state after firing of the composite laminate 29a shown in FIG.
FIG. 8 is a cross-sectional view schematically showing a multilayer ceramic substrate 39 according to another embodiment manufactured according to the present invention.
FIG. 9 is a cross-sectional view schematically showing a multilayer ceramic substrate 49 according to still another embodiment manufactured according to the present invention.
FIG. 10 is a cross-sectional view schematically showing a multilayer ceramic substrate 56 manufactured according to still another embodiment of the present invention.
[Explanation of symbols]
1,39,49,56 Multilayer ceramic substrate
2 Ceramic layer
3, 4 Inner conductor
5,6 Via-hole conductor
7, 14, 31, 32, 40, 47, 50, 57 Main surface
8-13, 41, 42 Connecting electrode
15, 16, 15a, 16a, 43, 44, 51, 52, 58 Projection
24 Green sheet for substrates
25,26 Green sheet for shrinkage suppression
27, 28 holes
29, 29a Composite laminate
30 Laminate for substrate
33, 34, 33a, 34a cavity
35, 36 Open end
37,38 Shrinkage suppression support
45 Electronic components
46 Solder
54 cap
60 lids

Claims (11)

A method for producing a multilayer ceramic substrate comprising a plurality of laminated ceramic layers and wiring conductors made of a ceramic material,
Preparing a plurality of substrate green sheets containing the ceramic material;
Preparing a plurality of shrinkage-suppressing green sheets containing ceramic that is not sintered at the firing temperature of the substrate green sheet;
Forming the wiring conductor on a specific one of the substrate green sheets;
Providing a hole in a specific one of the shrinkage-suppressing green sheets;
A laminate of a plurality of green sheets for a substrate, forming the wiring conductor, on a main substrate laminate to be a multilayer ceramic substrate, and on each main surface of the raw substrate laminate The shrinkage-suppressing green sheet is provided with a cavity having an opening end that is closed by at least one of the main surfaces of the raw substrate laminate. Forming such a composite laminate formed by the holes;
In order to obtain the multilayer ceramic substrate, the substrate laminate is sintered, but the shrinkage-suppressing green sheet is present as a shrinkage-suppressing support in an unsintered state, and the restraining force by the shrinkage-suppressing support The substrate laminate is substantially contracted only in the thickness direction while suppressing shrinkage in the plane direction of the substrate laminate by causing the substrate laminate to act on the substrate laminate. Firing the composite laminate so that a part of the cavity is raised along the inner surface of the cavity;
And a step of removing the shrinkage-suppressing support.   The method for manufacturing a multilayer ceramic substrate according to claim 1, wherein the cavity forms a bottomed recess.   The method for manufacturing a multilayer ceramic substrate according to claim 1, wherein the cavity forms a through hole.   The wiring conductor includes a via-hole conductor, and one end of the via-hole conductor is located in a portion of the main surface of the raw substrate laminate that closes the opening end of the cavity. A method for producing a multilayer ceramic substrate according to any one of 1 to 3.   The method for manufacturing a multilayer ceramic substrate according to claim 1, wherein the open end of the cavity has a spot shape.   The method for manufacturing a multilayer ceramic substrate according to claim 1, wherein the open end of the cavity has a longitudinal shape.   The wiring conductor is mainly composed of at least one selected from the group consisting of Ag, Ag-Pt alloy, Ag-Pd alloy, Cu, Ni, Pt, Pd, W, Mo, and Au. 7. A method for producing a multilayer ceramic substrate according to any one of 6 above.   The method for producing a multilayer ceramic substrate according to claim 1, wherein the step of firing the composite laminate is performed at a temperature of 1000 ° C. or lower.   The method for producing a multilayer ceramic substrate according to claim 8, wherein the shrinkage-suppressing green sheet contains at least one selected from alumina, zirconia, and magnesia. The method for producing a multilayer ceramic substrate according to any one of claims 1 to 9, wherein a load of 10 kg / cm ² or less is applied in the laminating direction in the step of firing the composite laminate. A multilayer ceramic substrate manufactured by the manufacturing method according to claim 1 .

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