JP2004152906A - Insulating substrate and ceramic package - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an insulating substrate and a ceramic package in which crack will not be generated even at high temperatures under high humidities. <P>SOLUTION: In the insulating substrate, a cavity 12 wherein an electronic element 4 is mounted therein is provided on a main surface, and a terminal electrode 3 is provided on a surface opposed to the main surface while a wiring conductor 2 for electrically connecting the electronic element 4 to the terminal electrode 3 is formed and a metallized layer for connecting a lid body is equipped on the main surface. Further, the minimum height thereof is not higher than 0.5mm. The area of a site on which the forming region of the cavity projected in a plane is superposed on the forming region of the terminal electrode is specified so as to be not wider than 10% of the whole area of the cavity. <P>COPYRIGHT: (C)2004,JPO

Description

【００７８】
【表２】

【００７９】
本発明の試料Ｎｏ．２、５、８、１０、１３〜３３は、残留応力が１９０ＭＰａ以下、面積比が１０％以下で、接合テスト及び封止テストでも異常は見られなかった。
【００８０】
一方、面積比が１１％以上と大きい本発明の範囲外の試料Ｎｏ．１、３、４、６、７、９、１１及び１２は、残留応力が２００ＭＰａ以上、面積比が１１％以上で、接合テスト及び／又は封止テストにおいてクラックが観察された。
【００８１】
【発明の効果】
本発明は、端子電極とキャビティとの交差部面積を制御することにより、パッケージ裏面部の残留応力を２５０ＭＰａ以下と低減し、基板底部におけるクラック発生を防止することができ、さらに強度を５００ＭＰａ以上、メタライズ層の接合強度を４９Ｎ以上とすることで、絶縁基板基板堤部の肉厚が０．１〜０．３ｍｍ、電子素子が実装される絶縁基板の基板底部の厚みが０．１〜０．３ｍｍ、絶縁基板の高さが０．５ｍｍ以下であるセラミックパッケージが安価に得られる。
【図面の簡単な説明】
【図１】本発明の絶縁基板の構造を示すもので、（ａ）は概略断面図、（ｂ）は概略平面図、（ｃ）はその部分拡大平面図である。
【図２】本発明の他の絶縁基板を示す概略平面図である。
【図３】本発明のセラミックパッケージの構造を示す概略平面図である。
【符号の説明】
１、１０１・・・絶縁基板
１ａ、１０１ａ・・・基板底部
１ｂ、１０１ｂ・・・基板堤部
２、１０２・・・配線導体
２ａ、１０２ａ・・・表面配線導体
２ｂ、１０２ｂ・・・内部配線導体
３、２３、１０３・・・端子電極
７、１０７・・・メタライズ層
８、１０８・・・メッキ層
９、１０９・・・共晶Ａｇ−Ｃｕロウ材
１２、３２、１１２・・・キャビティ
１５・・・交差部
１０４・・・電子素子
１０４ａ・・・電気部品
１０４ｂ・・・半導体素子
１０５・・・導電性接着剤
１０６・・・ワイヤボンディング
１１０・・・蓋体
Ｔ・・・絶縁基板の高さ
Ｄ・・・基板底部の厚み
ｄ・・・基板堤部の幅[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a ceramic package in which an electronic element and / or a semiconductor element is mounted and hermetically sealed by a lid such as a lid, particularly, a height of 0.5 mm or less and a bank width of 0.3 mm or less. Ultra-small and ultra-thin ceramic packages.
[0002]
[Prior art]
2. Description of the Related Art In recent years, with the increase in the degree of integration of semiconductor elements and the miniaturization of electrical components, various electronic devices have been reduced in size and function. Along with this, it is required to reduce the size of a ceramic package that houses electronic elements or mounts passive components at the same time as a semiconductor element. For example, a ceramic that has been reduced in size to about 3 mm in height, 2 mm in width, and 0.8 mm in height. A package is disclosed.
[0003]
However, further miniaturization is required for packages, and for example, ultra-small and ultra-thin ones represented by IC cards are required. In such an ultra-small and ultra-thin ceramic package, the electronic element is sealed with a lid in order to protect the electronic element from moisture in the atmosphere.
[0004]
For example, there is described a ceramic package for mounting a crystal oscillator inside, sealing with a lid, and protecting the crystal oscillator from the outside air.
[0005]
[Patent Document 1]
JP-A-2001-237665
[0006]
[Problems to be solved by the invention]
However, the ceramic package described in Patent Literature 1 has low corrosion resistance to water and has no problem immediately after production. However, in a hot and humid environment such as the rainy season, corrosion progresses with time, and cracks occur in the package. There was a problem.
[0007]
Accordingly, an object of the present invention is to provide an insulating substrate and a ceramic package that do not generate cracks even under high temperature and high humidity.
[0008]
[Means for Solving the Problems]
The present invention is based on the finding that residual stress affects water corrosion and crack generation of a ceramic package, and controls the area of an overlapping portion when a cavity and a terminal electrode are projected on a plane. This suppresses the occurrence of cracks.
[0009]
That is, in the insulating substrate of the present invention, a cavity in which an electronic element is mounted is provided on a main surface, and a terminal electrode is provided on an opposing main surface, and wiring is provided for electrically connecting the electronic element and the terminal electrode. A conductor is formed, and a metallized layer for bonding a lid is provided on the main surface, and the insulating substrate having a minimum height of 0.5 mm or less is formed such that a region where the cavity is projected in a plan view is the terminal. The area of a portion overlapping the electrode formation region is not more than 10% of the total area of the cavity.
[0010]
In particular, the insulating substrate is made of an alumina sintered body containing 4% by mass or more of a sintering aid, the alumina sintered body has a strength of 500 MPa or more, a Young's modulus of 320 GPa or less, and a thermal conductivity of 15 W / mK. It is preferable that it is above. Thus, even if stress is generated due to a difference in thermal expansion, the stress can be relieved by rapid heat dissipation and deformation, and destruction can be effectively prevented.
[0011]
Further, the alumina-based sintered body contains Mn in an amount of 2 to 8% by mass in terms of oxide and Si in an amount of 1 to 6% by mass in terms of oxide. ₂ O ₃ Is the main crystal phase, and MnAl ₂ O ₄ Preferably, it contains crystals. This makes it easy to increase the strength to 500 MPa or more and the thermal conductivity to 15 W / mK or more.
[0012]
Further, it is preferable that the adhesion strength of the metallized layer to the insulating substrate is 49 N or more. This effectively suppresses peeling that occurs between the metallized layer and the insulating substrate when the lid and the package are joined, and can achieve higher reliability.
[0013]
Furthermore, it is preferable that one terminal electrode is provided at each of the four corners of the opposing main surface. As a result, the connection structure can be simplified, connection from the outside is facilitated, and stress concentration can be suppressed.
[0014]
Further, a ceramic package according to the present invention is characterized in that a lid is joined to the main surface of the insulating substrate. Thereby, cracks under high temperature and high humidity can be suppressed, and high airtightness of the package can be realized.
[0015]
Particularly, the maximum residual stress at the bottom of the substrate is 250 MPa or less. Thereby, generation of cracks can be more effectively prevented.
[0016]
Further, it is preferable that the width of the bank portion of the ceramic package is 0.1 to 0.3 mm, and the thickness of the bottom of the insulating substrate on which the electronic element is mounted is 0.1 to 0.3 mm. By setting such dimensions, thermal stress destruction of the insulating substrate can be more effectively prevented, and the volume of the package can be further reduced.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
The insulating substrate of the present invention will be described with reference to the drawings.
[0018]
As shown in FIG. 1A, for example, the insulating substrate includes an insulating substrate 1 including a substrate bottom 1a and a substrate bank 1b, a wiring conductor 2 provided on the substrate bottom 1a, and an upper surface of the substrate bank 1b. And a metallized layer 7 formed in a ring shape. The insulating substrate 1 has a substrate bank 1b integrally provided on the outer periphery of a substrate bottom 1a.
[0019]
The wiring conductor 2 includes a surface wiring conductor 2a provided on the surface of the substrate bottom 1a and an internal wiring conductor 2b formed inside the substrate bottom 1a, and is provided on the back surface for electrical connection with the outside. It is connected to the terminal electrode 3.
[0020]
As shown in FIG. 1B, terminal electrodes 3 are provided at four corners on the surface of the substrate bottom 1a. Then, as shown in FIG. 2 (c) which is an enlarged view of FIG. 2 (b), when the cavity 12 formed by the substrate bottom 1a and the substrate bank 1b is projected on a plane parallel to the substrate, It is important that the area of the portion where the formation region overlaps with the formation region of the terminal electrode 3 is 10% or less of the entire area of the cavity 12.
[0021]
That is, in FIG. 1C, the area of the intersection 15 is represented by S ₀ , The area of the cavity 12 is S _cav And S ₀ Is S _cav Is important to be 10% or less of the area ratio S. ₀ / S _cav Corresponds to 0.1 or less. This is because a residual stress is generated due to a difference in thermal expansion coefficient between the metallized metal forming the terminal electrode 3 and the ceramics forming the substrate bottom 1a. ₀ Is small, it is possible to prevent cracks starting from near the intersection. That is, when the cavity 12 and the terminal electrode 3 are projected on a plane parallel to the insulating substrate 1 and a stress is generated at the intersection 15 and in the vicinity thereof, the thin portion of the substrate bottom 1a in contact with the cavity withstands the stress. It is considered that a crack occurs without cutting.
[0022]
Therefore, the area ratio S ₀ / S _cav Is 0.1 or less, the occurrence of cracks can be largely prevented. In particular, it is preferably 0.07 or less, more preferably 0.05 or less, and more preferably 0.03 or less. Most preferred is the area ratio S ₀ / S _cav Is 0, and there is no intersecting site.
[0023]
The shape of the terminal electrode 3 may be a square as shown in FIG. 1B, but in order to increase the length of one side of the terminal electrode 3, as shown in FIG. Alternatively, a shape in which one corner of a square is removed in a triangular shape may be used, and further, a shape (not shown) in which a corner is provided in one corner of a square in order to reduce residual stress.
[0024]
It is important that the minimum height of the insulating substrate 1 is 0.5 mm or less. If it is larger than 0.5 mm, the thickness of the ceramic package becomes large, and it becomes impossible to reduce the height of the device. In order to further reduce the height and secure the strength, the minimum thickness of the substrate bottom 1a is particularly preferably 0.4 mm or less.
[0025]
Further, the three-point bending strength of the alumina sintered body constituting the insulating substrate 1 is preferably 500 MPa or more. If the pressure is lower than 500 MPa, thermal stress is applied during sealing of the metal lid or during secondary mounting, and the metal lid is broken, or the metal lid is broken due to impact during handling or use. In order to be resistant to such thermal stress and impact force and to exhibit higher reliability, the strength is preferably at least 550 MPa, more preferably at least 600 MPa.
[0026]
In addition, the thermal conductivity radiates heat at the time of sealing to the outside of the system and can reduce a temperature difference within the insulating substrate 1, so that destruction at the time of sealing is more effectively prevented. It is preferably at least 15 W / mK, more preferably at least 20 W / mK, further preferably at least 25 W / mK.
[0027]
In addition, the Young's modulus is preferably 320 GPa or less, particularly 310 GPa or less, and more preferably 300 GPa or less, from the viewpoint that thermal stress tends to be absorbed by deformation and breakage is more effectively prevented.
[0028]
It is preferable that the adhesive strength of the metallized layer 7 to the insulating substrate 1 is 49 N or more. Thereby, peeling that occurs between the metallized layer 7 and the insulating substrate 1 when joining the lid and the package can be effectively suppressed, and higher reliability can be obtained.
[0029]
In FIG. 1, one terminal electrode 3 is provided at each of the four corners of the insulating substrate 1. This simplifies the structure, facilitates the connection to the terminal electrode 3 from the outside, and has symmetry, which is effective in dispersing the residual stress, and facilitates prevention of stress concentration.
[0030]
According to the present invention, it is important that the metallized layer 7 for joining the lid is provided on the main surface of the insulating substrate 1. Specifically, it is important that at least a portion of the substrate bank 1b is provided with a metallized layer 7 for joining the lid. In particular, the metallized layer 7 is preferably provided by simultaneous firing. This eliminates the need for a separate metallization layer forming step, so that the steps can be shortened, the product cost can be reduced, and the metallization layer 7 with high adhesion can be obtained.
[0031]
A plating layer made of a metal such as Ni, Co, Cr, Au and Cu may be formed on the surface of the metallized layer 7 for the purpose of preventing the diffusion of the brazing material and improving the adhesion strength. For example, a Ni plating layer and an Au plating layer can be sequentially formed on the surface of the metallized layer 7.
[0032]
The insulating substrate 1 contains alumina as a main component and a sintering aid of 4% by mass or more, particularly 6% by mass or more, and more preferably 8% by mass or more, so that it can be co-fired with the wiring conductor 2 and the metallized layer 7. Is preferred.
[0033]
The main component alumina preferably contains alumina in a proportion of 90% by mass or more, particularly 90 to 96% by mass, more preferably 93 to 96% by mass. This makes it easy to set the three-point bending strength of the insulating substrate 1 to 500 MPa or more, the thermal conductivity to 15 W / mK or more, and the Young's modulus to 320 GPa or less.
[0034]
As a second component, Mn is Mn. ₂ O ₃ It is preferably contained in a ratio of 2 to 8% by mass, particularly 3 to 8% by mass, and more preferably 3 to 6% by mass. This is because the Mn component acts as a sintering aid, and by selecting the above ratio, the sinterability is enhanced, and it is easy to achieve densification at a firing temperature of 1250 to 1400 ° C, MnAl ₂ O ₄ Is likely to be appropriately deposited. Such an appropriate amount of MnAl ₂ O ₄ Crystal precipitation has the effect of increasing the bending strength of the sintered body.
[0035]
Further, as a third component, Si is converted to SiO 2 ₂ The content is preferably 1 to 6% by mass, particularly 2 to 5% by mass, and more preferably 3 to 5% by mass. SiO ₂ Is involved in the generation of a liquid phase during sintering. Therefore, by selecting the above ratio, it is easy to achieve densification, and there is little residual amorphous phase. ₂ O ₄ It is easy to maintain high strength due to crystal precipitation.
[0036]
In addition, if desired, at least one of Mg, Ca, Sr, and Ba as a fourth component may be used to enhance the simultaneous sinterability with the wiring conductor. , May be contained at a ratio of 3% by mass or less in terms of oxide. Further, if desired, a metal such as W or Mo may be used as a fifth component as a component for blackening the sintered body in a proportion of 2% by mass or less based on 100% by mass of the composition up to the third component. May be included.
[0037]
The wiring conductor 2 and the metallized layer 7 are made of W and / or Mo as a main component and made of alumina in order to enable connection with various metal terminals or sealing of the lid, and maintain a strong adhesive force with the insulating substrate. It is preferably contained in an amount of 10% by mass or less, particularly 8% by mass or less.
[0038]
In the ceramic package of the present invention, for example, as shown in FIG. 3, an electronic element 104 such as an electric component 104a or a semiconductor element 104b is placed inside a cavity 112 of an insulating substrate 101, and a lid 110 is interposed via a metallization layer 107. In which the electrical components 104a and the semiconductor elements 104b connected to the wiring conductors 102 provided on the substrate bottom 101a of the insulating substrate 101 can be placed. The number of electronic elements 104 to be mounted is not particularly limited, and may be one or more.
[0039]
As the electrical component 104a, at least one of a crystal oscillator, a dielectric, a resistor, a filter, and a capacitor can be used, and the electrical component 104a can be electrically connected to the surface wiring conductor 102a using the conductive adhesive 105. It is possible. The semiconductor element 104b is connected to the wiring conductor 102 by wire bonding 106.
[0040]
The lid 110 is bonded to the substrate bank 101b via the metallization layer 107 to protect the electronic elements 104 such as the electric components 104a and the semiconductor elements 104b. Preferably, the alloy is a Fe—Ni—Co alloy having the following formula: By using such an alloy, thermal stress generated at the time of sealing can be reduced, and breakage of the insulating substrate 101 at the time of sealing can be more effectively prevented.
[0041]
Residual stress is generated in the substrate bottom 101a of the insulating substrate 101 of the ceramic package obtained by joining the lid 110 due to thermal contraction at the time of joining. If the residual stress increases, cracks may occur in the substrate bottom 101a, and in order to prevent this, it is preferable that the maximum residual stress (maximum residual stress) be 250 MPa or less. For this purpose, it is necessary to appropriately adjust the lid material, brazing material, joining conditions, and the like.
[0042]
According to the present invention, the width d of the substrate bank portions 1b and 101b is set to 0.1 to 0.3 mm, the thickness D of the substrate bottom portions 1a and 101a is set to 0.1 to 0.3 mm, and the height T of the package is set to 0.1 to 0.3 mm. Preferably, it is 0.3 to 0.5 mm. By setting these dimensions, the strength of the alumina-based sintered body as the insulating substrates 1 and 101 can be taken into account, and the damage to the thermal stress when the lid 110 is sealed can be more effectively prevented. The volume of the package can be made smaller.
[0043]
In particular, by setting the height T of the insulating substrate to 0.5 mm or less, it can be applied to an IC card or the like as a microminiature and ultrathin ceramic package on which electronic elements and / or semiconductor elements are mounted. In addition, it is preferable that the lid is thinner in that the height can be reduced. For example, it is preferably 0.3 mm or less, particularly 0.2 mm or less, and more preferably 0.1 mm or less.
[0044]
Next, a method of manufacturing the ceramic package according to the present invention will be described in detail with reference to a case in which a connecting substrate in which a plurality of insulating substrates are connected to each other is used and one of them is used separately.
[0045]
First, an alumina powder having an average particle diameter of 0.5 to 2.0 μm, particularly 1.0 to 1.5 μm is prepared as a raw material powder. By setting the average particle diameter to 0.5 μm or more, sheet formability can be ensured and powder cost increase can be easily prevented. Further, when the thickness is 2.0 μm or less, densification by firing at 1400 ° C. or less can be promoted, and sintering can be facilitated.
[0046]
Further, Mn having a purity of 99% or more and an average particle diameter of 0.5 to 5 μm as a second component. ₂ O ₃ Powder, SiO 3 having a purity of at least 99% and an average particle diameter of 0.5 to 3 μm as a third component ₂ Prepare powder. Note that Mn and Si may be added as carbonates, nitrates, acetates, and the like, which can form an oxide by firing, in addition to the above oxide powder.
[0047]
These components are based on the alumina powder, ₂ O ₃ 2 to 8% by weight, especially 3 to 8% by weight, more preferably 3 to 6% by weight, ₂ It is preferable to add the powder in an amount of 1 to 6% by mass, particularly 2 to 5% by mass, and more preferably 3 to 5% by mass in order to enhance sinterability and promote densification.
[0048]
If desired, at least one of Mg, Ca, Sr, and Ba may be 3% by mass or less in terms of oxide as a fourth component, and a metal powder of a transition metal such as W or Mo may be used as a fifth component. Oxide powder may be added as a coloring component at a ratio of 2% by mass or less in terms of metal.
[0049]
Further, Zr, Hf, and the like, which are well-known methods for improving strength and fracture toughness, may be appropriately added.
[0050]
After appropriately adding an organic binder to the above mixed powder, a green sheet for forming the insulating substrate 1 is prepared by a well-known molding method such as a pressing method, a doctor blade method, a rolling method, and an injection method. . For example, after a slurry is prepared by adding an organic binder and a solvent to the mixed powder, a green sheet is formed by a doctor blade method. Alternatively, an organic binder is added to the mixed powder, and a green sheet having a predetermined thickness can be produced by press molding, rolling molding, or the like.
[0051]
Since each insulating substrate has a small shape, it is preferable to form a plurality of insulating substrates on one connecting substrate and to use them separately in order to enhance productivity. To cope with this, a wiring conductor paste is applied to the green sheet by screen printing, gravure printing, or the like, on each green sheet, in the form of a wiring pattern for forming the wiring conductor 2, or in the metallization layer 7. Print and apply in a ring shape for formation.
[0052]
If desired, a via hole having a diameter of 50 to 250 μm is previously formed in the green sheet by a microdrill, a laser, or the like, and the above-described wiring conductor paste is filled in the via hole.
[0053]
As the wiring conductor paste, W and / or Mo is preferably used as a wiring conductor component, to which alumina powder is added in an amount of 10% by mass or less, particularly 8% by mass or less. This improves the adhesion between the alumina sintered body and the wiring conductor 2 while keeping the conduction resistance of the wiring conductor 2 low, and can easily prevent the occurrence of defects such as chipping of the plating. In order to improve the adhesion, a powder of the same composition as the oxide ceramic component forming the insulating substrate may be added instead of the alumina powder, and an oxide such as Ni may be added in an amount of 0.05 to 2% by volume. It is also possible to add in a ratio.
[0054]
Thereafter, the green sheet on which the wiring conductor paste is applied is printed and laminated and pressed. After that, a plurality of cutout grooves for separating the insulating substrate are formed. As a method of forming the notch groove, a method such as a cutter blade, a mold, and laser processing can be used, and among these, a mold and laser processing are particularly preferable because they can be mass-produced at low cost.
[0055]
The laminated body having the notched grooves formed therein is heated from a temperature of at least 1000 ° C. to a maximum firing temperature at a heating rate of 150 ° C./h or more, and fired in a non-oxidizing atmosphere at 1250 to 1400 ° C. It is important to fire at a cooling rate of 250 ° C./h or less.
[0056]
If the heating rate is less than 150 ° C./h between 1000 ° C. and the firing maximum temperature, the liquid phase generation in the low temperature liquid phase region at the time of heating becomes uneven, and the alumina grain growth is biased. As a result, bending strength may decrease. In particular, in order to further increase the strength, it is preferable that the heating rate be 180 ° C./h or more, and more preferably 200 ° C./h.
[0057]
Further, the sintering temperature sufficiently promotes densification, easily achieves a bending strength of 500 MPa or more, and lowers the adhesive strength with alumina due to progress of sintering of W and / or Mo itself, and reduces the particle size of alumina. Firing at 1250 to 1400 ° C. is preferable in terms of suppressing growth and improving mechanical and electrical reliability.
[0058]
The cooling rate from the holding temperature immediately after the completion of the firing to 1000 ° C. is preferably 250 ° C./h or less. MnAl ₂ O ₄ Can be easily crystallized, and the bending strength can be easily improved. The cooling rate is particularly preferably 200 ° C./h or less from the viewpoint of increasing the strength.
[0059]
The firing atmosphere is desirably a non-oxidizing atmosphere so that the metal is not oxidized. Specifically, it is desirable to use nitrogen or a mixed gas of nitrogen and hydrogen. For degreasing the organic binder, it is desirable that the atmosphere be a non-oxidizing atmosphere containing hydrogen and nitrogen and having a dew point of + 30 ° C. or lower, particularly 25 ° C. or lower. Note that an inert gas such as argon may be mixed into the atmosphere, if desired.
[0060]
A plating layer made of at least one of Ni, Co, Cr, Au and Cu may be formed on the wiring conductor 2 for surface protection and solder bonding.
[0061]
By the above-described manufacturing method, it is possible to manufacture the insulating substrate 1 which can be simultaneously fired with the metallized layer 7 and can be suitably used as a small ceramic package having a strength of 500 MPa or more. Further, the electronic element 4 and / or the semiconductor element 6 are mounted inside the obtained insulating substrate 1, electrically connected to the wiring conductor 2, and the plating layer 8 is formed on the surface of the ring-shaped metallized layer 7. And the lid 10 is joined by eutectic Ag-Cu brazing material 9 or the like by seam welding or the like. Thus, a semi-wiring conductor device in which the electronic element 4 is hermetically sealed can be obtained.
[0062]
The plating layer 8 is preferably made of at least one of Ni, Co, Cr, Au and Cu in order to prevent diffusion of the brazing material and obtain good adhesion.
[0063]
【Example】
For alumina powder having a purity of 99% or more and an average particle size of 1.5 μm, Mn having a purity of 99% or more and an average particle size of 0.7 μm is used. ₂ O ₃ Powder, SiO with purity of 99% or more and average particle diameter of 1.0 μm ₂ Powder, W powder having a purity of 99.9% or more and an average particle diameter of 1.2 μm, Mo powder having a purity of 99.9% or more and an average particle diameter of 1.2 μm, purity of 99.9% or more and an average particle diameter of 0.7 μm MgCO ₃ Powder, purity of 99% or more, CaCO having an average particle diameter of 1.3 μm ₃ Powder, SrCO with a purity of 99% or more and an average particle diameter of 1.0 μm ₃ Powder, BaCO ₃ Powder, Cr ₂ O ₃ Powder and Co ₃ O ₄ Powder was prepared.
[0064]
After mixing these raw material powders at the ratios shown in Table 1, an acrylic binder was used as a molding organic resin (binder) and toluene was used as a solvent to prepare a slurry, and then the slurry was prepared by a doctor blade method. A 150 μm green sheet was produced.
[0065]
After laminating the obtained green sheets to a predetermined thickness and performing degreasing in a nitrogen-hydrogen mixed atmosphere at a dew point of + 25 ° C., the temperature was continuously raised from 1000 ° C. to the maximum firing temperature at a temperature rising rate shown in Table 2, After firing for 1 hour in a nitrogen-hydrogen mixed atmosphere with a dew point of + 25 ° C. at the highest firing temperature, cooling was performed at a rate shown in Table 2 up to 1000 ° C.
[0066]
The main crystal phase of the obtained sintered body was identified by crushing the sintered body and X-ray diffraction. The bulk density was measured by the Archimedes method, and the relative density was calculated from the ratio to the theoretical density. The strength was measured at room temperature based on JISR1601 by preparing a beam-shaped sample having a thickness of 3 mm, a width of 4 mm, and a length of 40 mm.
[0067]
On the other hand, Cu, Au and Ag (low resistance metal) were added to W powder having an average particle diameter of 1.2 μm, Mo powder having an average particle diameter of 1.2 μm, and alumina powder having an average particle diameter of 1.5 μm. After preparing the composition as shown in No. 1, an acrylic binder and acetone were mixed as a solvent to prepare a wiring conductor paste.
[0068]
Then, the green sheet produced in the same manner as described above is punched to form a via hole having a diameter of 100 μm. Printing was applied in a pattern (wiring conductor) and a ring (metallized layer). At this time, the pattern shape was adjusted so that the total area of the portion facing the terminal electrode was 10% or less of the area of the cavity. In the green sheet on which the ring-shaped metallization was formed, a portion for housing the electronic element was removed by punching.
[0069]
The green sheets produced in this manner were aligned and laminated and pressed to produce a laminate. Thereafter, a notch groove is formed in the laminate, the molded body is degreased in a nitrogen / hydrogen mixed atmosphere at a dew point of + 25 ° C., and then degreased in a nitrogen / hydrogen mixed atmosphere at a dew point of + 25 ° C. The temperature was raised from 1000 ° C. to the maximum firing temperature at the temperature raising rate shown in Table 2, and after firing for 1 hour in a nitrogen-hydrogen mixed atmosphere with a dew point of + 25 ° C. at the maximum firing temperature, Table 2 shows the temperature up to 1000 ° C. Cooled at speed.
[0070]
The main crystal phase of the obtained sintered body was identified by crushing the sintered body and X-ray diffraction. Further, the bulk density was measured by the Archimedes method, and the porosity was calculated. The strength was measured at room temperature based on JIS R1601 by preparing a beam-shaped sample having a thickness of 3 mm, a width of 4 mm, and a length of 40 mm. Further, the average crystal particle diameter was measured by an intercept method and expressed as a particle diameter.
[0071]
The Young's modulus was measured at room temperature based on JIS R1602, and the thermal conductivity was measured at room temperature by a laser flash method. The dimensions of the insulating substrate were measured with a micrometer to calculate the size of the cavity, and the area of the intersection 15 was calculated from the size of the terminal electrode 3. The area of the intersection 15 was divided by the area of the cavity and expressed as a percentage as an area ratio.
[0072]
Next, electrolytic Ni plating was applied to the surface of the wiring conductor and the metallized layer formed in a ring shape, and further, 0.2 μm Au plating was applied to the surface. A 0.1 mm thick lid made of an Fe-Co-Ni alloy is joined to the ring-shaped metallized layer on which the plating layer 8 is formed by seam welding using a eutectic Ag-Cu brazing material, It was hermetically sealed.
[0073]
As a bonding test, the obtained sample was subjected to metallization peeling with a microscope of 40 magnifications, and cracks of the insulating substrate were confirmed.
[0074]
Next, a sample without metallized peeling or cracking was subjected to a heat cycle test up to 100 cycles, where a cycle of holding at -65 ° C. for 5 minutes and holding at 150 ° C. for 5 minutes was one cycle, and the hermetic sealing property was determined by the He leak method. A sealing test for evaluating the sealing state was performed.
[0075]
In the He leak method, the sample is taken out after being held in a 0.41 MPa He pressurized atmosphere for 2 hours, and the amount of He gas detected in a vacuum atmosphere is measured. ^-10 MPa ・ cm ³ 5 × 10 for / sec or less ^-9 MPa ・ cm ³ Those exceeding / sec were evaluated as x, and then the residual stress at the bottom of the substrate was measured by X-ray diffraction. The results are shown in Table 2. The residual stress was calculated from the diffraction peak (2θ) of 152 ° measured by X-ray diffraction using the parallel tilt method.
[0076]
The bonding strength of the ring-shaped metallization layer to the insulating substrate is determined by forming a 2 mm × 25 mm wiring conductor, applying electroless Ni plating, joining the metal fittings using a silver brazing, and peeling the metal fittings. Was measured for the peeling load. Further, the Young's modulus was measured at room temperature based on JIS R1602. Thermal conductivity was measured at room temperature by the laser flash method. The results are shown in Tables 1 and 2.
[0077]
[Table 1]

[0078]
[Table 2]

[0079]
Sample No. of the present invention In 2, 5, 8, 10, 13 to 33, the residual stress was 190 MPa or less, the area ratio was 10% or less, and no abnormality was observed in the bonding test and the sealing test.
[0080]
On the other hand, the sample No. having an area ratio as large as 11% or more and out of the range of the present invention. In 1, 3, 4, 6, 7, 9, 11, and 12, the residual stress was 200 MPa or more, the area ratio was 11% or more, and cracks were observed in the bonding test and / or the sealing test.
[0081]
【The invention's effect】
According to the present invention, by controlling the area of the intersection between the terminal electrode and the cavity, the residual stress on the back surface of the package can be reduced to 250 MPa or less, the occurrence of cracks at the bottom of the substrate can be prevented, and the strength can be reduced to 500 MPa or more. By setting the joining strength of the metallized layer to 49 N or more, the thickness of the insulating substrate substrate bank is 0.1 to 0.3 mm, and the thickness of the insulating substrate on which the electronic element is mounted is 0.1 to 0. A ceramic package having a height of 3 mm and a height of the insulating substrate of 0.5 mm or less can be obtained at low cost.
[Brief description of the drawings]
FIGS. 1A and 1B show the structure of an insulating substrate of the present invention, in which FIG. 1A is a schematic sectional view, FIG. 1B is a schematic plan view, and FIG.
FIG. 2 is a schematic plan view showing another insulating substrate of the present invention.
FIG. 3 is a schematic plan view showing the structure of the ceramic package of the present invention.
[Explanation of symbols]
1, 101 ... insulating substrate
1a, 101a ... substrate bottom
1b, 101b ... substrate bank
2, 102 ... wiring conductor
2a, 102a ... surface wiring conductor
2b, 102b ... internal wiring conductor
3, 23, 103 ... terminal electrodes
7, 107 ... metallized layer
8, 108 ... plating layer
9, 109: Eutectic Ag-Cu brazing material
12, 32, 112 ... cavity
15 ... intersection
104 ・ ・ ・ Electronic element
104a ... electric parts
104b ... Semiconductor element
105 ... conductive adhesive
106 ・ ・ ・ Wire bonding
110 ... lid
T: Height of insulating substrate
D: Thickness of substrate bottom
d: width of substrate bank

Claims (8)

A cavity in which an electronic element is mounted is provided on a main surface, and a terminal electrode is provided on an opposing main surface. A wiring conductor is formed for electrically connecting the electronic element and the terminal electrode. A metallized layer for bonding is formed on the main surface, and, on an insulating substrate having a minimum height of 0.5 mm or less, an area of a region where the cavity forming region projected in a plan view overlaps with the terminal electrode forming region. Is 10% or less of the total area of the cavity. The insulating substrate is made of an alumina sintered body containing 4% by mass or more of a sintering aid, and has a strength of 500 MPa or more, a Young's modulus of 320 GPa or less, and a thermal conductivity of 15 W / mK or more. The insulating substrate according to claim 1, wherein: The alumina-based sintered body contains 2 to 8% by mass of Mn in terms of oxide and 1 to 6% by mass of Si in terms of oxide, and has Al ₂ O ₃ as a main crystal phase. 3. The insulating substrate according to claim 1, wherein the grain boundary contains MnAl ₂ O ₄ crystal. The insulating substrate according to any one of claims 1 to 3, wherein an adhesion strength of the metallized layer to the insulating substrate is 49N or more. 5. The insulating substrate according to any one of 1 to 4, wherein one terminal electrode is provided at each of four corners of the opposing main surface. A ceramic package, wherein a lid is bonded to a main surface of the insulating substrate according to any one of the above items 1 to 5. 7. The ceramic package according to claim 6, wherein the maximum residual stress at the bottom of the substrate is 250 MPa or less. The width of the bank portion of the ceramic package is 0.1 to 0.3 mm, and the thickness of the bottom of the insulating substrate on which the electronic element is mounted is 0.1 to 0.3 mm. 7. The ceramic package according to 7.

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