JP2004349288A - Process for producing ceramic multilayer substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process for producing a ceramic multilayer substrate in which residual particles of a ceramic member are prevented from being generated in a recess formed by closing a through hole for castellation. <P>SOLUTION: The process for producing a ceramic multilayer substrate 10 by pressure sintering a ceramic green sheet 18 becoming one major surface side of a laminate 16 provided with a through hole 15 for castellation 14 and a ceramic sheet 20 becoming the other major surface side not provided with a hole communicating with the through hole 15 while superposing comprises a step for forming a tapered part 19 in the through hole 15 by irradiating the ceramic green sheet 18 with laser light, a step for filling the through hole 15 with a ceramic member 21, a step for pressure sintering the ceramic sheet 20, the ceramic green sheet 18 and an unsintered ceramic sheet 22 while superposing, and a step for removing the unsintered ceramicsheet 22 and the ceramic member 21 from a sintered compact 23 to form the laminate 16. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a ceramic multilayer substrate formed by firing a laminate having castellations on side surfaces of a plurality of ceramic substrates while applying pressure.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, some ceramic multilayer substrates have a castellation in which a concave portion is formed on a side surface of a plurality of ceramic base materials, and a conductive metal film is provided in the concave portion to serve as an electrode for an external connection terminal. As shown in FIGS. 3 (A) and 3 (B), a through hole 51 for castellation of a conventional ceramic multilayer substrate is formed, for example, by a punching method including a pin 52 and a die 53, before the ceramic base material is fired. The green sheet 54 is placed on a die 53 and formed by punching out the ceramic green sheet 54 with pins 52 in a direction perpendicular to the thickness direction.
[0003]
With reference to FIGS. 4A to 4C, a method for manufacturing the conventional ceramic multilayer substrate 50 will be described. As shown in FIG. 4 (A), a conductor metal paste is applied on the wall surface of the castellation through-hole 51 of the ceramic green sheet 54 composed of one or a plurality of sheets by screen printing or the like to form a through-hole conductor 55. Is formed. On the other hand, a ceramic substrate 56 composed of one or a plurality of sheets having no insertion hole communicating with the through hole 51 is prepared. The ceramic substrate 56 having no insertion hole may be a ceramic green sheet before firing or a fired ceramic sheet. Next, as shown in FIG. 4 (B), the ceramic green sheet 53 and the ceramic base material 56 are overlapped, and furthermore, the ceramic members which are superimposed and are not sintered at the firing temperature of the ceramic green sheet 53 on the lower surface. The unsintered ceramic sheet 57 made of is laminated and fired while applying pressure to form a fired body. Next, as shown in FIG. 4C, the unsintered ceramic sheet 57 adhered as the upper and lower surfaces of the fired body is removed by sandblasting or the like, so that a laminate 58 is formed, and substantially the holes are formed. The ceramic multilayer substrate 50 with the castellations 60 is manufactured by being cut along the dividing line 59 passing through the central line.
[0004]
Here, the above-mentioned pressure firing is to overlap the ceramic green sheets before firing the ceramic base material with the aim of reducing the firing shrinkage of the laminate and improving the dimensional accuracy of the substrate, and further, This is a method in which a ceramic sheet made of a ceramic member that does not sinter at the firing temperature of the ceramic green sheet is superimposed on the lower surface, fired while pressing, and then the ceramic sheet is removed to produce a laminate (for example, Patent Document 1). 1).
[0005]
In addition, the ceramic multi-layer substrate is fired for the purpose of suppressing the firing shrinkage of the ceramic green sheet with the fired ceramic substrate, thereby suppressing the firing shrinkage of the entire substrate to be small, and manufacturing the substrate with high accuracy. It has been proposed that an unfired ceramic green sheet on which a conductor wiring pattern is printed in advance is superimposed on the ceramic substrate and thermocompression-bonded, followed by firing to produce a ceramic multilayer substrate (for example, Patent Document 2). reference).
[0006]
Also, the method of forming a through hole in a ceramic green sheet is to form a small hole that cannot be formed by a method using a pin and a die, and to fill this hole with a conductive metal to improve the mounting density. It has been proposed to form a through-hole in the shape of a drum when viewed in cross section by irradiating a laser beam (for example, see Patent Document 3).
[0007]
[Patent Document 1]
JP-A-5-503498 [Patent Document 2]
JP 2001-267743 A [Patent Document 3]
JP-A-11-54885
[Problems to be solved by the invention]
However, the conventional method for manufacturing a ceramic multilayer substrate as described above has the following problems.
(1) In the case where the laminate is formed by firing while applying pressure, since the interior of the through-hole for castellation is hollow, the pressure causes deformation of the hole.
(2) In order to prevent the deformation in (1), it is conceivable to previously fill the holes with a ceramic member that does not sinter at the firing temperature of the ceramic green sheet and perform pressure firing. However, in the case of a laminate having a plurality of ceramic base materials on one main surface side and having a recess formed by closing a castellation through hole, a ceramic member is filled in the recess and pressure firing is performed. Even if it is performed, when the ceramic member is removed from the concave portion by sand blasting or the like after firing, the wall of the through hole is straight, so that the ceramic member at the bottom peripheral portion of the concave portion cannot be completely removed, and particles remain, and the particles are removed later. In a process to be performed, for example, in a plating process, defects such as non-sticking of plating occur.
[0009]
(3) An unfired ceramic green sheet on which a conductive wiring pattern has been printed in advance is laminated on a fired ceramic substrate and thermocompression-bonded, and then fired to form a ceramic multilayer substrate. Of the ceramic green sheet cannot be sufficiently suppressed even if only one side of the fired ceramic substrate is suppressed. Accordingly, defects such as peeling between the fired ceramic green sheet and the fired ceramic substrate, cracks in the fired ceramic green sheet, and warpage of the fired ceramic green sheet and fired ceramic substrate laminate. May occur.
(4) A case in which a through hole is formed in a ceramic green sheet by irradiating a laser beam to form a drum-shaped through hole in a cross-sectional view and the through hole for castellation is closed and formed. In this case, a ceramic member is filled into the concave portion and pressure firing is performed. After the firing, when the ceramic member is removed from the concave portion by sandblasting or the like, the wall surface of the through-hole has a drum shape. The particles tend to collect and cannot be completely removed, leaving particles, which may cause problems such as non-plating in a later step, for example, a plating step.
The present invention has been made in view of the above circumstances, and provides a method of manufacturing a ceramic multilayer substrate that prevents generation of particles remaining in a ceramic member in a recess formed by closing a castellation through hole. The purpose is to:
[0010]
[Means for Solving the Problems]
The method for manufacturing a ceramic multilayer substrate according to the present invention, which meets the above object, comprises the steps of: forming one or a plurality of ceramic base green unfired ceramic green sheets on one main surface side of a laminate including a plurality of ceramic bases; A through hole for castellation is provided, and a ceramic green sheet and a ceramic sheet are provided without providing a through hole communicating with the through hole in one or a plurality of fired ceramic sheets of a ceramic base material on the other main surface side. In the method for manufacturing a ceramic multilayer substrate formed by sintering and pressing while laminating, the ceramic green sheet is irradiated with laser light, the diameter of the through hole on the side where the laser light comes into contact is increased, and the side on which the laser light exits In the step of forming a tapered portion on the side wall of the through-hole by drilling the diameter of the through-hole small, and the firing temperature of the ceramic base material in the through-hole, A step of filling a ceramic paste made of a ceramic member not to be bonded from a side having a large through-hole, and a step of filling a ceramic green sheet into one or a plurality of ceramic sheets serving as the other main surface side. An unsintered ceramic sheet made of a ceramic member that does not sinter at the firing temperature of the ceramic green sheet is superimposed on the lower surface, and fired while applying pressure. Forming a fired body; and removing the unsintered ceramic sheet and the ceramic member filled in the through hole from the fired body to form a laminate.
[0011]
This makes it possible to easily provide a tapered portion in the through-hole so as to have a large diameter on the outer surface side by the laser beam, and to sinter the ceramic substrate easily filled from the large-diameter through-hole at the firing temperature. For example, abrasive particles for blasting can be radiated to the entire surface up to the bottom of the ceramic member which is not used, so that the generation of residual particles of the ceramic member can be prevented. In addition, since the ceramic multilayer substrate is manufactured by firing while being pressed, the shrinkage of the substrate during firing can be suppressed, and the substrate can be made highly accurate, and at the same time, problems such as peeling between the substrates, cracking and warping of the substrate occur. Can be prevented.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention.
Here, FIGS. 1A and 1B are explanatory views of a ceramic multilayer substrate manufactured by the method for manufacturing a ceramic multilayer substrate according to one embodiment of the present invention, and FIGS. It is explanatory drawing of the manufacturing method of the same ceramic multilayer substrate.
[0013]
With reference to FIGS. 1A and 1B, a description will be given of a ceramic multilayer substrate 10 manufactured by a method for manufacturing a ceramic multilayer substrate 10 according to an embodiment of the present invention. As shown in FIG. 1A, the ceramic multilayer substrate 10 is formed by a ceramic substrate 11 formed of, for example, a low-temperature fired ceramic substrate, and a plurality of ceramic substrates 11 are stacked and fired while applying pressure. ing. In the ceramic multilayer substrate 10, for example, a concave portion is formed on the side surface of the substrate, a conductive metal film 12 is provided on the surface of the concave portion, and a conductive pattern 13 is provided on the substrate surface connected to the concave portion. And a castellation 14 for performing the operation. The wall surface of the through hole 15 provided in the ceramic base material 11 for forming the castellation 14 has a taper in which the hole diameter on the outer surface side of the plurality of ceramic base materials 11 is large and the hole diameter on the bottom side on the internal side is small. It has a shape.
[0014]
As shown in FIG. 1B, the ceramic multilayer substrate 10 having the castellations 14 is a plurality of, for example, a plurality of large ceramic substrates for forming four ceramic multilayer substrates 10 at one time. It is formed from a laminate 16 in which sheets are laminated. The laminated body 16 has a through-hole 15, a conductive metal film 12, a conductive pattern 13, and the like at predetermined positions of each large sheet-shaped ceramic substrate. It is formed by firing. Then, the laminated body 16 formed by firing is divided by the dividing lines 17 so as to pass substantially through the center of the through hole 15, thereby forming the individual ceramic multilayer substrates 10.
[0015]
Next, a method of manufacturing the ceramic multilayer substrate 10 according to one embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 2A, unfired ceramic of a large sheet-shaped ceramic substrate serving as a ceramic base 11 forming one main surface side of a ceramic multilayer substrate 10 according to one embodiment of the present invention. The green sheet 18 is made of a low-temperature fired ceramic. Ceramic green sheet 18 made of the low temperature co-fired ceramic, for _example, a _{CaO-Al 2 O 3 -SiO 2} -B 2 O 3 based glass 50-65% by weight (preferably 60 wt%), the _Al 2 _{O 3} A resin, a solvent, and a plasticizer are added to and mixed with 50 to 35% by weight (preferably 40% by weight) of ceramic powder, and the mixture is formed into a sheet having a desired thickness by a doctor blade method or the like. And is formed in a rectangular shape of a desired size. The ceramic green sheet 18 is irradiated with a laser beam by using a laser beam machine such as a YAG laser or a carbon dioxide laser, and the diameter A of the through hole 15 on the side where the laser beam comes into contact is large. The through hole 15 for the castellation 14 having the tapered portion 19 on the side wall of the ceramic green sheet 18 is formed such that the diameter B of the through hole 15 on the exit side is reduced.
[0016]
In the case where one main surface side of the ceramic multilayer substrate 10 is formed of a plurality of ceramic green sheets 18, the tapered portions 19 are formed by irradiating a laser beam to each of the ceramic green sheets 18. When superimposed, the entire tapered portion 19 can be formed to be a straight line with a small step. Alternatively, the tapered portion 19 can be formed by irradiating a laser beam to a joined body in which a plurality of ceramic green sheets 18 are first overlapped and temporarily joined.
[0017]
The fired ceramic sheet 20 which is the other main surface side of the ceramic multilayer substrate 10 is formed by pressing unfired ceramic green sheets of one or more large-sized sheet-shaped ceramic substrates serving as the ceramic base material 11 in advance. It is formed by firing. This ceramic sheet 20 is not provided with an insertion hole communicating with the through hole 15 formed in the ceramic green sheet 18.
[0018]
Next, as shown in FIG. 2B, in the ceramic green sheet 18 in which the through-holes 15 are formed, a conductor made of a low melting point metal such as Ag-based or Cu-based is provided on the tapered portion 19 of the through-hole 15. The conductive metal film 12 is formed by screen printing or the like using the paste. On the outer surface side of the ceramic green sheet 18, a conductor pattern 13 is formed by screen printing or the like using the same conductor paste as the conductor metal film 12. Then, inside the through hole 15 in which the conductive metal film 12 is formed, a ceramic member 21 in the form of a ceramic paste that does not sinter at the firing temperature of the ceramic green sheet 18 is formed by screen printing or the like from the side where the diameter of the through hole 15 is large. Will be filled.
[0019]
Although not shown, the outermost surface of the fired ceramic sheet 20 on the other main surface side of the ceramic multilayer substrate 10 usually has a wiring pattern. In order to electrically connect the wiring pattern with the conductive metal film 12 and the conductive pattern 13, the ceramic sheet 20 on the outer surface and the ceramic sheet 20 on the inner layer in the case of a plurality of sheets, Via conductors and wiring patterns using the same conductive paste as the conductive metal film 12 are formed.
[0020]
Next, as shown in FIG. 2C, a ceramic green sheet 18 is provided in the fired ceramic sheet 20 on the other main surface side of the ceramic multilayer substrate 10 by forming through holes formed in the ceramic green sheet 18. 15 are overlapped so that the side with the smaller hole diameter is in contact and the larger side is the outer surface. Further, an unsintered ceramic sheet 22 made of a ceramic member that does not sinter at the firing temperature of the ceramic green sheet 18 is overlaid on the lower surface of the ceramic sheet 20 and the ceramic green sheet 18 which are overlapped. The sintered body 23 is formed by firing at a temperature of, for example, about 800 to 1100 ° C. while applying pressure from above the unsintered ceramic sheet 22 superposed on both surfaces.
[0021]
Next, as shown in FIG. 2D, the unsintered ceramic sheet 22 remaining without sintering in the fired body 23 and the ceramic member 21 filled in the through-hole 15 are, for example, , And are removed by sandblasting or the like. As a result, a laminate 16 including a plurality of ceramic substrates 11 provided with a plurality of ceramic multilayer substrates 10 is formed. The laminate 16 is cut at a dividing line 17 passing through the center line of the through hole 15 at a predetermined position. Thus, the ceramic multilayer substrate 10 having the castellations 14 on the side surfaces of the substrate is manufactured.
[0022]
【The invention's effect】
In the method for manufacturing a ceramic multilayer substrate according to claim 1, the ceramic green sheet is irradiated with a laser beam, and the diameter of the through hole on the side contacting the laser beam is increased, and the diameter of the through hole on the exit side is reduced. A step of forming a tapered portion on the side wall of the through hole, a step of filling the through hole with a ceramic paste made of a ceramic member that does not sinter at the firing temperature of the ceramic base material from the side with the larger diameter of the through hole, and the other main surface The ceramic green sheet is superimposed on one or more ceramic sheets on the side such that the side with the larger diameter of the through hole becomes the outer surface. A step of laminating unsintered ceramic sheets made of non-sintered ceramic members and firing them under pressure to form a fired body; Since there is a step of forming a laminate by removing the unsintered ceramic sheet and the ceramic member filled in the through hole from the body, it is easy to provide a tapered portion in the through hole so as to have a large diameter on the outer surface side. The ceramic member easily filled from the large-diameter through-hole can be irradiated with, for example, blasting abrasive grains over the entire surface up to the bottom, thereby preventing generation of particles remaining in the ceramic member. Further, by firing under pressure, the shrinkage of the substrate can be suppressed and the substrate can be made with high precision, and at the same time, the occurrence of problems such as peeling between the substrates and cracking and warping of the substrate can be prevented.
[Brief description of the drawings]
FIGS. 1A and 1B are explanatory views of a ceramic multilayer substrate manufactured by a method for manufacturing a ceramic multilayer substrate according to an embodiment of the present invention.
FIGS. 2A to 2D are explanatory views of a method for manufacturing the same ceramic multilayer substrate.
FIGS. 3A and 3B are explanatory views of a conventional method for forming a through hole for castellation of a ceramic multilayer substrate.
FIGS. 4A to 4C are explanatory views of a conventional method for manufacturing a ceramic multilayer substrate.
[Explanation of symbols]
10: ceramic multilayer substrate, 11: ceramic base material, 12: conductive metal film, 13: conductive pattern, 14: castellation, 15: through hole, 16: laminated body, 17: division line, 18: ceramic green sheet, 19 : Taper portion, 20: ceramic sheet, 21: ceramic member, 22: unsintered ceramic sheet, 23: fired body

Claims (1)

A through hole for castellation is provided in one or more unfired ceramic green sheets of the ceramic base material on one main surface side of the multilayer body composed of a plurality of ceramic base materials, and the other main surface side One or more of the fired ceramic sheets of the ceramic base material are not provided with an insertion hole communicating with the through hole, and the ceramic green sheet and the ceramic sheet are stacked and fired while being pressed. In the method for manufacturing a ceramic multilayer substrate to
The ceramic green sheet is irradiated with laser light, the diameter of the through-hole on the side where the laser light comes into contact is increased, and the diameter of the through-hole on the side where the laser light exits is reduced to form a side wall of the through-hole. Forming a tapered portion on
Filling the through-hole with a ceramic paste made of a ceramic member that does not sinter at the firing temperature of the ceramic base material from the side with the larger diameter of the through-hole;
The ceramic green sheet is superimposed on one or a plurality of the ceramic sheets on the other main surface side such that the side with the larger diameter of the through hole becomes the outer surface, and furthermore, the superimposed upper and lower A step of laminating an unsintered ceramic sheet made of a ceramic member that does not sinter at the firing temperature of the ceramic green sheet on the surface, and firing while pressing to form a fired body,
A method of manufacturing a ceramic multilayer substrate, comprising a step of removing the unsintered ceramic sheet and the ceramic member filled in the through hole from the fired body to form the laminate.

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