JP2005276910A - Ceramic substrate, package for accommodating electronic component, and electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide ceramic substrate where the base material at the bottom surface of the concave section is thin, the height of the rear face can be lowered further, and deformation is not generated at the bottom surface of the concave section. <P>SOLUTION: The ceramic substrate comprises the base material 1 formed by laminating a plurality of ceramic layers 1a, and the concave section 2 formed to the principal surface of the base material 1. Thickness of the base material 1 at the bottom surface of the concave section 2 ranges to 0.2 mm from 0.05 mm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a ceramic substrate formed by laminating ceramic layers, an electronic component storage package formed using the ceramic substrate, and an electronic device.

  Ceramic substrates used for electronic component storage packages for storing electronic components such as semiconductor elements such as optical semiconductor elements and semiconductor integrated circuit elements, crystal resonators, piezoelectric ceramic parts, surface acoustic wave elements, capacitive elements, etc. The structure includes a base body formed by laminating ceramic layers, and a recess for storing an electronic component formed on the main surface of the base body.

  An electronic component housing package is formed by forming a wiring conductor on the ceramic substrate base so as to lead out from the inside of the recess to the outer surface of the base.

  The electronic component is stored in the recess of the electronic component storage package, the electronic component is joined to the bottom surface of the recess through a brazing material, resin, glass, and the like, and the electrode of the electronic component is electrically connected to the wiring conductor, The recess is closed with a lid or the like and the electronic component is hermetically sealed to complete the electronic device.

  The completed electronic device is mounted and used as a component in an electronic device such as a mobile phone or a digital camera.

  Such a ceramic substrate is generally manufactured by the following method.

First, a raw material powder such as aluminum oxide or silicon oxide is kneaded with an organic solvent and a binder to prepare a ceramic slurry, and then the ceramic slurry is formed into a sheet shape by a processing method such as a doctor blade method, and a plurality of green sheets Next, a part of the green sheet is punched to form an opening for forming a recess, and then a plurality of green sheets are formed with the opening formed as an upper layer. In addition to being laminated so as to be positioned at the same position, pressure is applied from above and below with a large pressure of about 4 MPa to 20 MPa, the layers are brought into close contact to form a green ceramic laminate, and then the green ceramic laminate is fired.
Japanese Patent No. 347269

  Recently, in response to the downsizing and thinning of electronic devices used in electronic devices, the ceramic substrate used in the electronic component storage package and the like has been strongly demanded to be thin.

  When the thickness of the ceramic substrate is reduced, the height required to accommodate the electronic component in the recess is at a minimum, and therefore it is necessary to reduce the thickness of the substrate on the bottom surface of the recess as much as possible.

However, in the conventional ceramic substrate, when the thickness of the base at the bottom of the recess is made thinner than 0.3 mm, there is a problem that the base is deformed at the bottom of the recess and the flatness is lowered. . The flatness can be measured by the moire interference method or the like. For example, when the thickness of the substrate on the bottom surface of the recess is 0.2 mm, six or more moire interference fringes with a 10 μm interval between contour lines are generated. The interval between the contour lines means a difference in height of the surface of the object to be measured, which corresponds between adjacent contour lines. If parallel light is used, the interval (Δh) between the contour lines of the interference fringes is determined according to the light incident / exit angle (θ) to the grating and the grating interval (p). (For example, JP 2002-39726 A)
(Expression) Δh = p / (2 tan θ)
When the flatness of the substrate is lowered at the bottom surface of the recess, the electronic component cannot be normally stored in the recess and fixed to the bottom surface of the recess, and the electrodes of the electronic component can be securely connected to the corresponding wiring conductor. It causes problems such as being unable to do so.

  In addition, for example, when the electronic component is an optical semiconductor element such as a CCD (Charge Coupled Device), if the lid body is slightly inclined with respect to the light receiving surface on the upper surface of the optical semiconductor element, the lid body is transmitted into the recess. Incident light is distorted with respect to the light receiving surface and cannot be received accurately. For this reason, conventionally, it has been necessary to secure a thickness of 0.3 mm or more on the bottom surface of the recess, and there is a problem that it is difficult to make the substrate thinner.

  The deformation of the base body at the bottom of the recess is considered to be caused by the following reasons.

That is,
A large pressure of about 4 MPa to 20 MPa applied when the green sheets are laminated and adhered is directed to the bottom surface of the thin recess through the portion surrounding the recess in the green sheet (laminate), and the bottom surface of the recess is directed toward the center. The stress is transmitted as pressing force, and the thin green sheet is bent and deformed by this stress.

  In addition, the pressure at this time is efficiently transmitted to the portion surrounding the concave portion, but does not act directly on the bottom surface of the concave portion. Since it is in a state of being easily deformed, the deformation of the substrate on the bottom surface of the recess as described above is very likely to occur.

  The present invention has been devised in order to solve the above-described conventional problems. The object of the present invention is to make the bottom surface thin, for example, less than about 0.3 mm, and to further reduce the height. An object of the present invention is to provide a ceramic substrate with good flatness on the bottom surface of a recess, an electronic component storage package using the ceramic substrate, and an electronic device.

  When the thickness of the substrate is thinner than the conventional 0.3 mm, the difference is only about 0.1 mm, which seems easy, but it is 67% when converted to the thickness ratio. The thickness of the sheet will be reduced to a very large ratio as shown below, and in such a thin area, even if the thickness is slightly reduced, the mechanical strength of the green sheet is significantly reduced. Deformation of the substrate on the bottom surface of the recess is very likely to occur with a large pressure of about 4 MPa to 20 MPa applied when closely contacting. It is extremely difficult to reduce the thickness of the difference of 0.1 mm. Conventionally, such a thin ceramic substrate has not been provided.

  Further, as a method for increasing the flatness of the surface of a substrate such as a ceramic substrate, surface polishing processing such as lapping and polishing is known, and it is considered that such polishing processing is performed on a substrate. However, when the thickness of the base at the bottom of the recess is 0.05 mm to 0.2 mm, the thickness of the base is very thin and the mechanical strength is low. Mechanical destruction will occur.

  In addition, it is possible to increase the flatness by grinding the unevenness on the bottom surface of the recess by blasting such as sandblasting, but in this case, the surface roughness on the bottom surface of the thin recess becomes rough and the thickness is partially increased. Therefore, as in the case of the above-described polishing, defects such as cracks are easily induced in the substrate. In addition, when an electronic component is mounted on the bottom surface of the recess through the bonding material, the flow of the bonding material may be deteriorated.

  The ceramic substrate of the present invention comprises a substrate formed by laminating a plurality of ceramic layers, and a recess formed on the main surface of the substrate, and the thickness of the substrate on the bottom surface of the recess is 0.05 mm to 0 mm. .2 mm.

In the ceramic substrate of the present invention, the recess has an area of a bottom surface of 25 mm ^{2 to} 121 mm ² and has no more than 5 interference fringes when measured by a moire interferometry with a contour line interval of 10 μm. It is characterized by this.

  The ceramic substrate of the present invention is characterized in that the interference fringes are concentrically formed around a central portion of the bottom surface of the recess.

  In the electronic component storage package of the present invention, a wiring conductor is formed on the base of the ceramic substrate having the above-described structure so as to be led out from the inside of the recess to the outer surface, and the electronic component is stored in the recess. It is characterized by that.

  According to another aspect of the present invention, there is provided an electronic device including the electronic component storage package having the above-described configuration and an electronic component that is stored in the recess and is electrically connected to the electrode. .

  According to the ceramic substrate of the present invention, since the thickness of the substrate at the bottom surface of the recess is 0.05 mm to 0.2 mm, the thickness of the substrate can be made as thin as the thickness of the electronic component.

  In this case, since the thickness of the substrate is only about 0.1 mm thinner than the conventional thickness of 0.3 mm, it seems to be not very effective at first glance, but it is represented by mobile phones with cameras and digital cameras. In electronic products that require the incorporation of thin optical semiconductor elements for imaging, optical semiconductor storage packages such as CCD sensors and CMOS sensors for incorporating optical semiconductor elements, and semiconductors for IC cards In fields where thinning is strongly demanded, such as packages for housing integrated circuits, this thinning can provide a significant effect.

  As a result, it is possible to provide a ceramic substrate that is effective for reducing the thickness of electronic component storage packages and electronic devices.

Further, the ceramic substrate of the present invention is the area of the bottom surface of the recess is 25 mm ² to 121mm ² or less, when the interference fringes produced as measured by moire interferometry in which the contour interval between 10μm is not more than five Is a semiconductor element such as an optical semiconductor element or a semiconductor integrated circuit element, a piezoelectric vibrator such as a crystal vibrator or a ceramic piezoelectric part, a surface acoustic wave element, a capacitor element, etc. Electronic components can be stored efficiently. At the same time, since the number of occurrence of interference fringes is small and the flatness is good, the electronic component can be fixed on the bottom surface of the recess at a normal position without causing problems such as tilt. As a result, it is possible to provide a ceramic substrate capable of more reliably forming a thin and highly functional electronic component storage package or electronic device.

  Further, in the ceramic substrate of the present invention, when the interference fringes are formed concentrically around the central portion of the bottom surface of the concave portion, the bottom surface of the concave portion is high in the central portion, and is entirely directed toward the outer peripheral portion. Since the shape gradually decreases in the circumference, for example, when an electronic component is placed on the bottom surface of the recess and bonded and fixed with a bonding material, the center of the bottom surface of the electronic component is placed at the center of the recess. The portion of the electronic component is placed between the lower surface of the electronic component and the bottom surface of the recess, and a pool of adhesive that gradually increases toward the outer peripheral portion of the electronic component is formed. It can be securely fixed firmly.

  According to the electronic component storage package of the present invention, the wiring conductor is formed on the base of the ceramic substrate having the above-described configuration so as to be led out from the inside of the recess to the outer surface, and the electronic component is stored in the recess. Therefore, an electronic component storage package capable of forming a thin and highly functional electronic device can be provided.

  In addition, the electronic device of the present invention includes the electronic component storage package having the above-described configuration and the electronic component that is housed in the recess and is electrically connected to the electrode, so that the electronic device is thin and highly functional. can do.

  The ceramic substrate, electronic component storage package, and electronic device of the present invention will be described in detail below.

  FIG. 1 is a cross-sectional view showing an embodiment of a ceramic substrate, an electronic component storage package and an electronic device according to the present invention. In FIG. 1, reference numeral 1 denotes a substrate formed by laminating a plurality of ceramic layers 1a. The ceramic substrate 3 of the present invention is formed by the base 1 and the recess 2.

  Further, an electronic component storage package 5 is formed by forming the wiring conductor 4 on the base 1 of the ceramic substrate 3, and an electronic device 7 is formed by storing the electronic component 6 in the electronic component storage package 5.

  The ceramic layer 1a includes ceramics such as an aluminum oxide sintered body, a glass ceramic sintered body, an aluminum nitride sintered body, a mullite sintered body, a barium titanate sintered body, and a lead titanate sintered body. It is formed by a sintered body. In addition, the kind of ceramic sintered compact can be suitably selected according to the use of a ceramic substrate. For example, when emphasizing the mechanical strength of the substrate 1, each ceramic layer 1a is formed of an aluminum oxide sintered body or the like. Further, in the case where a portion having a large capacitance is secured in the substrate 1, the corresponding ceramic layer 1a is formed of a barium titanate sintered body having a large relative dielectric constant.

  For example, if each ceramic layer 1a is made of an aluminum oxide sintered body, the substrate 1 is formed by forming a ceramic powder such as aluminum oxide into a sheet shape on a support together with an organic solvent, a binder, and the like. A green sheet is produced, and a predetermined shape is punched to form a frame-shaped ceramic green sheet. Thereafter, a ceramic green sheet that has not been punched is positioned in the lower layer, and the frame-shaped ceramic green sheet is The ceramic green sheet laminate is formed by being laminated so as to be positioned in the upper layer, and is manufactured by firing.

  In the ceramic substrate 3 of the present invention, the thickness of the substrate 1 on the bottom surface of the recess 2 is 0.05 mm to 0.2 mm.

  By making the thickness of the base 1 at the bottom surface of the recess 2 0.05 mm to 0.2 mm, the thickness of the base 1 is reduced to, for example, the same level as the thickness of the electronic component 5 housed in the recess 2. Can do.

  In this case, since the thickness of the substrate is only about 0.1 mm thinner than the conventional thickness of 0.3 mm, it seems to be not very effective at first glance, but it is represented by mobile phones with cameras and digital cameras. In electronic products that require the incorporation of thin optical semiconductor elements for imaging, optical semiconductor storage packages such as CCD sensors and CMOS sensors for incorporating optical semiconductor elements, and semiconductors for IC cards In fields where thinning is strongly demanded, such as packages for housing integrated circuits, this thinning can provide a significant effect.

  As a result, a ceramic substrate effective for reducing the thickness of the electronic component storage package 5 and the electronic device 7 can be provided.

  If the thickness of the substrate 1 on the bottom surface of the recess 2 exceeds 0.2 mm, the thickness is not sufficiently reduced as compared with the conventional ceramic substrate, and sufficient effects can be obtained in applications such as the above electronic devices. Can't get. Further, if the thickness is less than 0.05 mm, the mechanical strength of the ceramic substrate 3 becomes too weak. Therefore, a machine such as a crack in the base 1 due to stress such as thermal stress when the electronic component 6 is mounted on the bottom surface of the recess 2. Therefore, the reliability as a ceramic substrate used in applications such as an electronic component storage package becomes insufficient. Therefore, the thickness of the substrate 1 on the bottom surface of the recess 2 needs to be 0.05 mm to 0.2 mm.

Further, in the ceramic substrate 1 of the present invention, when the area of the bottom surface of the recess 2 and 25 mm ² to 121mm ^2, and the interference fringes produced as measured by Moire Interferometry the contour interval was 10μm and five or less Is
The area of the bottom surface of the recess 2 is sufficiently wide to make a semiconductor element such as an optical semiconductor element or a semiconductor integrated circuit element, a piezoelectric vibrator such as a crystal vibrator or a ceramic piezoelectric component, a surface acoustic wave element, a capacitor element, etc. The component 6 can be stored efficiently.

  At the same time, since the number of interference fringes is small and the flatness of the bottom surface of the recess 2 is good, the electronic component 6 can be fixed on the bottom surface of the recess 2 in a normal position without causing problems such as tilt. . As a result, it is possible to provide a ceramic substrate that can more reliably form a thin and highly functional electronic component storage package 5 or electronic device 7.

In this case, when the area of the bottom surface of the recess 2 is 25 mm ² or less, it becomes difficult to efficiently store the electronic component 6. When the area exceeds 121 mm ² , the mechanical strength of the ceramic substrate 31 becomes too weak, and thus the thin recess 2 There is a possibility that mechanical destruction such as cracks is likely to occur due to stress such as thermal stress when the electronic component 6 is mounted on the bottom surface of the substrate.

If the number of interference fringes exceeds 5, the flatness of the bottom surface of the recess 2 becomes insufficient. For example, when the electronic component 6 is stored in the recess 2 when used as an electronic component storage package. In addition, it is difficult to fix the electronic component 6 at a predetermined position, and it becomes difficult to accurately connect the electrode of the electronic component 6 to the corresponding wiring conductor 4, or the electronic component 6 is inclined. When the electronic component 6 is tilted, for example, when the electronic component 6 is an optical semiconductor element, the light receiving surface on the upper surface is tilted, and the light receiving accuracy tends to deteriorate. Thus, the recess 2 is the area of the bottom surface is 25 mm ² to 121mm ² or less, interference fringes that occur when measured by moire interferometry in which the contour interval between 10μm is preferably not less five.

  In this case, the contour line corresponds to the position where each interference fringe is generated, and the interval between the contour lines means the difference in height of the surface of the object to be measured corresponding to the adjacent contour lines. That is, when the interval between the contour lines is 10 μm, one interference fringe is generated every time the surface height of the object to be measured (the bottom surface of the recess 2) changes by 10 μm.

The concave portion 2 having a bottom area of 25 mm ^{2 to} 121 mm ² is, for example, a square having a side length of 5 mm × 5 mm to 11 mm × 11 mm, or a rectangular shape such as a rectangle having such an area. In this case, the corner portion is not formed into a perfect quadrangle shape, but the corner portion is formed into an arc shape to prevent the base body 1 from being cracked or the like more effectively, or is stored in applications such as an electronic component storage package. Depending on the shape of the electronic component, a part of the outer side may be bent or bent outward or inward.

  Further, the measurement of the bottom surface of the concave portion 2 by the moire interferometry is performed by setting a diffraction grating having a grating interval of 20 μm directly above the concave portion 2 and then passing through the diffraction grating so that the incident / exit angle is 45 degrees from the upper side of the grating. This can be done by irradiating the bottom surface of the recess with light from a light source and measuring the number of interference fringes (moire fringes) generated by superimposing the diffraction grating image reflected by the bottom surface of the recess and the diffraction grating itself. The diffraction grating is manufactured, for example, by forming a light-shielding portion on a glass plate with the lattice-like pattern as described above.

  In this case, the interval (Δh) between the contour lines indicated by the interference fringes is determined according to the light incident / exit angle (θ) to the grating and the grating interval (p) if parallel light is used. (Refer to the following formula.) In order to make the light emitted from the light source parallel light, a lens is disposed between the light source and the grating.

(Expression) Δh = p / (2 tan θ)
For example, when θ = 45 degrees and p = 20 μm, Δh = 20 / (2 tan 45 °) = 10 μm.

  In the ceramic substrate 3 of the present invention, the interference fringes are preferably generated concentrically around the central portion of the bottom surface of the recess 2.

  When the interference fringes are formed concentrically around the central portion of the bottom surface of the concave portion 2, the bottom surface of the concave portion 2 is high at the central portion and has the same inclination toward the outer peripheral portion, Since the height gradually becomes lower, for example, when the electronic component 6 is placed on the bottom surface of the recess 2 and fixed with a bonding material as will be described later, an electron is placed at the center of the recess 2. Since the central portion of the bottom surface of the component 6 is placed, a pool of bonding material that gradually increases toward the outer peripheral portion of the electronic component 6 is formed between the lower surface of the electronic component 6 and the bottom surface of the recess 2. The electronic component 6 can be more securely and firmly bonded and fixed to the bottom surface of the recess 2.

  By forming the wiring conductor 4 on the ceramic substrate 3 from the inside of the recess 2 to the outer surface of the base 1, an electronic component storage package in which the electronic component 6 is stored in the recess 2 is formed.

  The wiring conductor 4 is made of a metal material such as tungsten (W), molybdenum (Mo), manganese (Mn), copper (Cu), silver (Ag), palladium (Pd), gold (Au), platinum (Pt), etc. For example, it is formed by printing a conductor paste prepared by adding an organic solvent and a binder to a tungsten powder and kneading it on the surface of the ceramic green sheet forming the substrate 1 to form a conductor layer. .

  As described above, the electronic component 6 is a semiconductor element such as an optical semiconductor element or a semiconductor integrated circuit element, a piezoelectric vibrator such as a crystal vibrator or a ceramic piezoelectric part, a surface acoustic wave element, a capacitor element, or the like. And bonded and fixed to the bottom surface of the recess 2 by a bonding material such as resin, brazing material, or glass.

  The electrode of the electronic component 6 housed in the recess 2 is connected to a portion of the wiring conductor 4 exposed in the recess 2 via a conductive connecting material such as a bonding wire 8 or solder (not shown). Are electrically connected.

  In this case, the wiring conductor 4 is formed on the base 1 of the ceramic substrate 3 having the above-described structure so as to be led out from the inside of the recess 2 to the outer surface, and the electronic component 6 is accommodated in the recess 2. It is possible to provide an electronic component storage package capable of forming a highly functional electronic device 7.

  The surface of the wiring conductor 4 is nickel (Ni), cobalt (Co), Cu for preventing corrosion of the wiring conductor 4 or for improving the bonding property of the bonding wire 8 and the wettability of solder. Pd, Pt, Au, etc. may be plated.

  After the electronic component 6 is stored in the recess 2 of the electronic component storage package 5, the lid 9 is attached to the upper surface of the base 1 to close the recess 2 or sealing in the recess 2 as necessary. The electronic device 7 is formed by sealing the electronic component 6 by means such as filling a resin (not shown).

  According to the electronic device 7 of the present invention, since the electronic component 6 is housed and formed in the electronic component housing package 5 having the above-described configuration, the electronic device 7 can be made thin and highly functional.

  Attachment of the lid 9 to the base body 1 can be performed by a method of bonding via a bonding material such as a brazing material, glass, a resin adhesive, or a method such as welding.

Next, the ceramic substrate 1 of the present invention, the thickness of the substrate 1 on the bottom surface of the recess 2 and 0.05mm to 0.2 mm, preferably, the area of the bottom surface 25 mm ² to 121mm ² or less, 10 [mu] m spacing contours The manufacturing method in which the interference fringes generated when measured by the moire interferometry described above is 5 or less will be specifically described with an example.

  The lowering of the flatness of the bottom surface of the recess 2 due to deformation of the base 1 due to deformation or the like is caused by pressing the ceramic green sheet laminate with a large pressure of about 4 MPa to 20 MPa when the base is manufactured. Therefore, in order to increase the flatness, it is only necessary to reduce the pressure of the pressurization and ensure the adhesion between the layers of the ceramic green sheets. The specific example described below is an example thereof, and the ceramic green sheet has a two-layer structure including a layer containing a molten component, and when the ceramic green sheets are stacked vertically, the molten component is melted to In this method, the layers of the ceramic green sheets are brought into close contact with each other.

  FIG. 2 is a cross-sectional view for each process showing an example of the method for producing the ceramic substrate 1 of the present invention, wherein 11 is a support, 14 is a ceramic green sheet, 15 is a conductor layer, and 16 is a ceramic green sheet laminate. In this example of the manufacturing method, the ceramic green sheet 14 is formed of a first ceramic green sheet layer 12 and a second ceramic green sheet layer 13.

  First, as shown in FIG. 2A, the first ceramic green sheet layer 12 is formed on the support 11, and then, as shown in FIG. 2B, the first ceramic green sheet layer 12 is formed on the first ceramic green sheet layer 12. Two ceramic green sheet layers 13 are formed to form a ceramic green sheet 14.

  As the first ceramic green sheet layer 12 and the second ceramic green sheet layer 13, a mixture of ceramic powder, an organic binder, a solvent and the like is used. The first ceramic green sheet layer 12 further contains a molten component. Both the first ceramic green sheet layer 12 and the second ceramic green sheet layer 13 may be added with a plasticizer to adjust the hardness and strength of the ceramic green sheet 14.

Examples of the ceramic powder include composite perovskite ceramic powders such as Al ₂ O ₃ , AlN, glass ceramic powder (a mixture of glass powder and filler powder), BaTiO ₃ system, PbTiO ₃ system, and the like. It is appropriately selected according to the required characteristics.

Examples of the glass component of the glass ceramic powder include SiO ₂ —B ₂ O ₃ system, SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ system, SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —MO system (however, , M is composed of Ca, Sr, Mg, Ba or Zn), SiO ₂ —Al ₂ O ₃ —M ₁ O—M ₂ O system (where M 1 and M 2 may be the same or different, and Ca, Sr, Mg , Ba or Zn), SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —M ¹ O—M ² O (wherein M ¹ and M ² may be the same or different and may be Ca, Sr, Mg, Ba or Zn), SiO ₂ —B ₂ O ₃ —M ³ ₂ O system (where M ³ is composed of Li, Na or K), SiO ₂ —B ₂ O ₃ —Al ₂ O _3- M ³ ₂ O system (however, M ³ is made of Li, Na or K), Pb glass, Bi glass and the like.

Further, as the filler powder of the glass ceramic powder, for example, a composite oxide of Al ₂ O ₃ , SiO ₂ , ZrO ₂ and an alkaline earth metal oxide, a composite oxide of TiO ₂ and an alkaline earth metal oxide, A ceramic powder such as a composite oxide (for example, spinel, mullite, cordierite) containing at least one selected from Al ₂ O ₃ and SiO ₂ can be used.

  As the organic binder blended in the ceramic green sheet 14, those conventionally used for ceramic green sheets can be used. For example, acrylic (acrylic acid, methacrylic acid or their homopolymer or copolymer Polymer, specifically acrylic ester copolymer, methacrylic ester copolymer, acrylic ester-methacrylic ester copolymer, etc.), polyvinyl butyral, polyvinyl alcohol, acrylic-styrene, polypropylene Examples include carbonate-based and cellulose-based homopolymers or copolymers. In view of decomposition and volatility in the firing step, an acrylic binder is more preferable.

  The molten component contained in the first ceramic green sheet layer 12 is in a molten state upon heating when the ceramic green sheet laminate 6 is produced, and is a hydrocarbon, fatty acid, ester, fatty alcohol, polyhydric alcohol. Etc. Considering the solubility in a solvent when preparing the slurry, hydrocarbons, esters, fatty alcohols and polyhydric alcohols having a small molecular weight and polarity are preferred. Further, in view of compatibility with the above-described acrylic binder, esters, fatty alcohols, and polyhydric alcohols are more preferable.

  Among the above-mentioned melting components, those having a melting point of 35 to 100 ° C. are preferred. This is because when the melting point in this range is used, the first ceramic green sheet layer 12 is not softened and deformed at room temperature. Therefore, handling up to the lamination process is facilitated, and the ceramic green sheet laminate 16 is formed. This is because organic components such as a binder and a plasticizer in the ceramic green sheet 14 are not decomposed during heating in the production process, and therefore delamination does not occur due to the decomposition gas. Specific examples of the melting component having a melting point of 35 to 100 ° C. include hexadecanol, polyethylene glycol, polyglycerol, stearylamide, oleylamide, ethylene glycol monostearate, paraffin, stearic acid, and silicone.

  The content of the molten component contained in the first ceramic green sheet layer 12 varies depending on the binder component to be used and the amount thereof and the molten component to be used, but the first ceramic green sheet layer is in a melted state. 12 may be an amount that softens and deforms following the shape of the second ceramic green sheet layer 13 of the ceramic green sheet 14 located below and the metal paste 15 formed thereon.

  The first ceramic green sheet layer 12 is a slurry obtained by adding a solvent (organic solvent, water, etc.) to the ceramic powder, organic binder, and molten component, and a predetermined amount of plasticizer and dispersant as required. It is obtained by molding on a support such as a PET film by a doctor blade method, a lip coater method, a die coater method or the like. The thickness of the first ceramic green sheet layer 2 is formed to be thicker than the thickness of the conductor layer in order to fill the step between the conductor layer and the ceramic green sheet.

  The second ceramic green sheet layer 13 is formed using a slurry that does not contain a molten component with respect to the slurry used for the first ceramic green sheet layer 12.

  The method for forming the second ceramic green sheet layer 13 on the first ceramic green sheet layer 12 is as follows. (1) The second ceramic green sheet layer 13 formed in the same manner as the first ceramic green sheet layer 12 is (2) A slurry of the second ceramic green sheet 13 is applied on the first ceramic green sheet layer 12 formed on the support 11. And (3) a method in which a slurry of the second ceramic green sheet layer 13 is applied on the slurry of the first ceramic green sheet layer 12 applied on the support 11.

  When the second ceramic green sheet layer 13 is laminated on the first ceramic green sheet layer 12, a gap is generated between the first ceramic green sheet layer 12 and the second ceramic green sheet layer 13. In order to improve the adhesion between the first ceramic green sheet layer 12 and the second ceramic green sheet layer 13, the method (2) or (3) is preferable. Furthermore, the method (3) is more preferable because the first ceramic green sheet layer 12 and the second ceramic green sheet layer 13 are formed almost simultaneously, which simplifies the process. In the method (3), an extrusion method such as a die coater method or a lip coater method may be used. These are non-contact coating methods, and a slurry having a relatively low viscosity and a small amount of solvent is used. Therefore, the ceramic green sheet 14 may be formed without mixing the slurry of the first ceramic green sheet layer 12 and the slurry of the second ceramic green sheet layer 13.

  Next, as shown in FIG. 2 (c), a part of the ceramic green sheet 14 is subjected to punching such as punching using a die and formed into a frame shape, and the second ceramic green sheet layer 13 is formed. A conductor layer 15 is formed thereon. As a method for forming the conductor layer 15 on the ceramic green sheet 14, for example, a conductor paste obtained by pasting a conductor material powder such as tungsten is printed by a screen printing method or a gravure printing method, or by a plating method or a vapor deposition method. A method of directly forming on a ceramic green sheet 14 to form a metal film having a predetermined pattern shape, a conductor thick film formed into a predetermined pattern shape by printing, a metal foil processed into a predetermined pattern shape, a plating method, a vapor deposition method, etc. There is a method of transferring the metal film having a predetermined pattern shape formed by the above method onto the ceramic green sheet 14. Examples of the conductive material include one or more of W, Mo, Mn, Au, Ag, Cu, Pd, Pt, and the like. In the case of two or more, any form such as mixing, alloy, coating, etc. There may be.

  The conductor layer 15 is formed on the second ceramic green sheet layer 13 of the ceramic green sheet 14. This is because since the second ceramic green sheet layer 13 does not contain a melting component that melts when heated, the second ceramic green sheet layer 13 is not deformed when heated, so that the conductor layer 15 is formed thereon. This is to prevent the conductor layer 15 from being deformed.

  In addition, before forming the conductor layer 15, a through-hole conductor such as a via-hole conductor or a through-hole conductor for connecting the conductor layers 15 between the upper and lower layers may be formed as necessary. These through conductors are formed by means such as embedding a paste of conductor material powder (conductor paste) by printing or press filling into a through hole formed in the ceramic green sheet 14 by punching or laser processing.

  Next, as shown in FIG. 1 (d), the stacked ceramic green sheets 14 are aligned at a temperature at which the molten component becomes molten and the first ceramic green sheet layer 12 is softened and deformed, that is, the molten component. The ceramic green sheet laminated body 16 is produced by heating at a temperature of about the melting point. At this time, the first ceramic green sheet layer softened so that the laminated ceramic green sheets 14 are not displaced so that the ceramic green sheets 14 ′ serving as the bottom surfaces of the recesses 2 are not deformed. If pressure is applied so as to assist in deforming following the pattern shape of the second ceramic green sheet layer 13 and the conductor layer 15 formed thereon, more accurate and reliable crimping Is possible.

  The pressurization in this case is about 0.5 MPa, for example, and is a very small pressure of about 1/8 to 1/40 compared to the conventional high pressure of 4 to 20 MPa.

  As described above, when the upper and lower ceramic green sheets are brought into close contact with each other, only heating to the melting point or higher of the molten component, or heating and pressurization with a very small pressure are performed. A large stress does not act through the portion surrounding the recess 2, and it is possible to effectively prevent bending and deformation of the thin green sheet.

  In the process of producing the ceramic green sheet laminate 16, the first ceramic green sheet layer 12 contains a melting component that melts when heated, and thus the ceramic green sheet 14 on which the conductor layer 15 is formed is laminated and heated. In this case, the first ceramic green sheet layer 12 is softened, so that the first ceramic green sheet layer 12 is formed on the second ceramic green sheet layer 13 of another ceramic green sheet 14 located thereunder and on the second ceramic green sheet layer 13. The conductor layer 15 is deformed following the shape of the conductor layer 15. As a result, the ceramic green sheets 14 are brought into close contact with each other without generating voids around the conductor layer 15 or between the conductor layers 15, and the electronic component obtained by firing the ceramic green sheet laminate 16 is free from delamination. It will not be.

  In addition, since the first ceramic green sheet layer 12 contains a melting component that melts when heated, the first ceramic green sheet layer 12 softens and has adhesiveness only by heating. There is no need to press the ceramic green sheet 14 by pressure. And since the 2nd ceramic green sheet layer 13 in which the conductor layer 15 is formed does not contain the melting component which melts at the time of heating, the 2nd ceramic green sheet layer 13 does not change at the time of heating, and laminated ceramic Further, the softened first ceramic green sheet layer 12 is deformed so as to follow the shape of the pattern of the second ceramic green sheet layer 13 and the conductor layer 15 formed thereon so that the green sheet 14 is not displaced. It will not be deformed to the extent that it is pressed to assist it. Accordingly, the ceramic green sheet laminate 16 and the conductor layer 15 formed thereon are not deformed, and the ceramic green sheet laminate 16 obtained without any distortion to the green sheet 14 due to pressurization is fired. The ceramic substrate 3 (electronic component storage package 5) obtained in this manner has high dimensional accuracy and effectively prevents deformation such as warpage on the bottom surface of the recess 2.

For example, when a conventional green sheet that needs to pressurize the upper and lower ceramic layers with a large pressure of about 4 MPa to 20 MPa is used, the flatness and the interval between the contour lines on the bottom surface of the concave portion 2 of the ceramic green sheet laminate 16 and the ceramic substrate are set. The number of interference fringes generated when measured by the moire interferometry of 10 μm was 7 to 9, and the number of interference fringes greatly exceeded 5. As described above, the first containing a molten component When the ceramic green sheet layer 12 is used, the number of interference fringes on the bottom surface of the concave portion 2 of the ceramic green sheet laminate 16 and the ceramic substrate 3 is about 1 to 5, and it has been experimentally found that the flatness is greatly improved. did. The above example is the case bottom area of the recess 2 is 25mm ² ~121mm ^2.

  As the ceramic green sheet positioned at the bottom of FIG. 1D, that is, the ceramic green sheet forming the bottom surface of the recess 2, a ceramic green sheet 4 ′ composed only of the second ceramic green sheet layer 3 is used. Good. Further, in the case of an electronic component storage package in which the wiring conductors 4 are exposed on both main surfaces of the substrate 1, a substrate in which the conductor layers 15 are formed on both surfaces of the lowermost ceramic green sheet 14 'may be used.

  Finally, the ceramic green sheet laminate 16 is fired to produce the ceramic substrate 3 (electronic component storage package 5) of the present invention. The firing step consists of removing organic components and sintering the ceramic powder.

  Removal of the organic component is performed by heating the ceramic green sheet laminate 16 in a temperature range of 100 to 800 ° C., and the organic component is decomposed and volatilized. The sintering temperature varies depending on the ceramic composition, and ranges from about 800 to 1600 ° C. Do it within. The firing atmosphere varies depending on the ceramic powder and the conductor material, and is performed in the air, in a reducing atmosphere, in a non-oxidizing atmosphere or the like, and may contain water vapor or the like in order to effectively remove organic components.

When a low-temperature sintered material such as glass ceramic is used as the ceramic material, if a constrained green sheet is further laminated on the upper and lower surfaces of the ceramic green sheet laminate 16 and fired, and the restraint sheet is removed after firing, It becomes possible to obtain the ceramic substrate 3 with higher dimensional accuracy. The constrained green sheet is a green sheet mainly composed of a hardly sinterable inorganic material such as Al ₂ O ₃ and does not shrink during firing. In the laminate in which the constraining green sheets are laminated, the constraining green sheet that does not shrink is prevented from shrinking in the laminating plane direction (xy plane direction) and shrinks only in the laminating direction (z direction). Is suppressed. If the constraining green sheet at this time is also configured to have a first ceramic green sheet layer 12 and a second ceramic green sheet layer 13 similar to the ceramic green sheet 14 of the present invention, the constraining green sheets are laminated and pressure-bonded. In particular, a large pressing force is not required, and the obtained ceramic substrate 3 (electronic component storage package 5) may be of higher dimensional accuracy.

In addition to the hardly sinterable inorganic component, the constrained green sheet may contain a glass component having a softening point equal to or lower than the firing temperature, for example, the same glass as the glass in the ceramic green sheet 14. This is because the glass softens and bonds with the ceramic green sheet 14 during firing, so that the bond between the ceramic green sheet 14 and the constraining green sheet becomes strong, and a more reliable restraining force can be obtained. When the glass amount at this time is 0.5 to 15% by mass with respect to the inorganic component including the hardly sinterable inorganic component and the glass component, the binding force is improved and the firing shrinkage of the constraint green sheet is 0.5%. It is suppressed to the following.

  After firing, the constraining sheet is removed. Examples of the removing method include water jet, chemical blasting, sand blasting, wet blasting (a method of spraying abrasive grains and water by air pressure) and the like.

  In addition, when performing blasting such as water blasting as described above, it is necessary to prevent blasting from directly hitting the bottom surface of the thin recess 2 after removing the restraint sheet. If the blast injection directly hits the bottom surface of the recess, there is a risk of causing problems such as cracks in the base 1 at the bottom surface of the recess 2.

  Since the ceramic substrate 3 (electronic component storage package 5) manufactured by the above method does not have delamination inside and has high dimensional accuracy, the ceramic substrate 3 (electronic component storage package 5). ) Excellent electrical characteristics and high airtightness required as

It is sectional drawing which shows an example of embodiment of the ceramic substrate of this invention, the package for electronic component accommodation, and an electronic device. (A)-(d) is sectional drawing for every process which shows an example of the manufacturing method of the ceramic substrate of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Base | substrate 2 ... Recessed part 3 ... Ceramic substrate 4 ... Wiring conductor 5 ... Electronic component storage package 6 ... Electronic component 7 ... Electronic device 8 ... Bonding wire 9 ... Lid 11 ·· Support 12 · · First ceramic green sheet layer 13 · Second ceramic green sheet layer 14 · Ceramic green sheet 15 · · Conductor layer

Claims (5)

  It comprises a substrate formed by laminating a plurality of ceramic layers and a recess formed on the main surface of the substrate, and the thickness of the substrate on the bottom surface of the recess is 0.05 mm to 0.2 mm. And ceramic substrate. Said recess is in the area of the bottom surface is 25 mm ² to 121mm ² or less, according to claim 1, wherein the interference fringes produced as measured by moire interferometry in which the contour interval between 10μm is equal to or less than five Ceramic substrate.   The ceramic substrate according to claim 2, wherein the interference fringes are concentrically formed around a central portion of the bottom surface of the recess.   A wiring conductor is formed on the base of the ceramic substrate according to any one of claims 1 to 3 so as to be led out from the inner side to the outer surface of the concave portion, and an electronic component is accommodated in the concave portion. Electronic component storage package.   5. An electronic device comprising: the electronic component storage package according to claim 4; and an electronic component that is stored in the recess and is electrically connected to the electrode.

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