JP4540297B2 - Low-temperature fired porcelain composition, low-temperature fired porcelain, and wiring board - Google Patents

Description

【００５３】
【表２】

【００５４】
表２の結果から明らかなように、本発明の試料Ｎｏ．２〜８、１１、１４では、何れも１ＧＨｚにおける比誘電率が７．３以下と低くなり、かつ、抗折強度が２８０ＭＰａ以上と高かった。これに焼成温度を９００〜９７５℃とした本発明の試料Ｎｏ．３〜８、および１４では、何れもコーディライトおよびサフィリンが検出され、そのＸ線回折におけるピーク強度比Ｓ／Ｃが０．１７以上となり、１ＧＨｚにおける比誘電率を７以下で抗折強度を２８５ＭＰａ以上にできた。特に、試料Ｎｏ．６、７では、Ｘ線回折におけるピーク強度比Ｓ／Ｃが０．３３以上となり、比誘電率は６．９以下とさらに低くでき、かつ、機械的強度を３１５ＭＰａ以上にまで高めることができた。
【００５５】
一方、磁器の組成範囲を本発明の範囲外とした試料Ｎｏ．１、９、１０、１２、１３、１５では、焼成後の磁器が未焼結かまたは過焼結となった。または比誘電率が高いかまたは低い抗折強度しか得られなかった。
【００５６】
【発明の効果】
以上詳述したように、本発明の低温焼成磁器組成物及び低温焼成磁器では、ＳｉＯ_２、Ｂ_２Ｏ_３、Ａｌ_２Ｏ_３およびＭｇＯを主成分として含むガラス成分とアルミナとを所定の割合で組み合わせることにより磁器の低誘電率化を図ることができる。特に、磁器中に少なくともコーディライト及び／またはサフィリンを含有させることにより、低誘電率かつ高強度化を図ることができる。
【００５７】
以上詳述したように、本発明の低温焼成磁器組成物では、ＳｉＯ_２、Ｂ_２Ｏ_３、Ａｌ_２Ｏ_３およびＭｇＯを主成分として含むガラス成分とアルミナとを所定の割合で組み合わせることにより、得られる低温焼成磁器の１ＧＨｚにおける比誘電率を７．５よりも低くでき、機械的強度を２８０ＭＰａ以上に高めることができる。特に、低温焼成磁器中に少なくともコーディライト及び／またはサフィリンを含有させることにより、さらに低誘電率かつ高強度化を図ることができる。
【図面の簡単な説明】
【図１】 本発明の配線基板の一実施例を説明するための概略断面図である。
【符号の説明】
１ 絶縁基板
２ 蓋体
３ メタライズ配線層
４ 接続端子
４ａ 電極パッド
４ｂ ボール状端子
５ 半導体素子
６ キャビティ
７ 絶縁体
８ 配線導体
９ 電極層
１０ ビアホール導体
Ａ 半導体素子収納用パッケージ
Ｂ 外部電気回路基板[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a low-temperature fired ceramic composition, a low-temperature fired ceramic, and a wiring board, and in particular, a low-temperature fired ceramic having a low dielectric constant and high strength, and a wiring used for a semiconductor element storage package using the same as an insulating layer. It relates to a substrate.
[0002]
[Prior art]
In recent years, mobile devices such as mobile phones and PDAs have been rapidly developed as electronic devices that process high-frequency signals of the GHz level or higher, such as optical communication and high-speed interfaces. As a wiring board used for such electronic devices, it has a lower relative dielectric constant and can withstand unexpected drops and impacts when being carried in order to suppress attenuation of transmission signals due to dielectric loss. There is a need for an insulating substrate having sufficient mechanical strength.
[0003]
In place of the conventionally used insulating substrate made of alumina ceramics, low-temperature fired porcelain formed by mixing a glass component and a filler component capable of lowering the dielectric constant than alumina has been developed. For example, according to Patent Document 1 shown below, a mixture of glass powder containing alumina, SiO ₂ , Al ₂ O ₃ , B ₂ O _3, alkaline earth metal oxide, and the like and alumina powder is baked and crystallized. By depositing strontium feldspar as a phase, an insulating substrate is reduced in dielectric constant and strength.
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 7-58454
[Problems to be solved by the invention]
However, the low-temperature fired ceramic described in Patent Document 1 described above has a problem that the mechanical strength is still low although the relative dielectric constant is as low as 5 at the minimum. On the other hand, attempts have been made to increase the strength of porcelain, but in this case, the relative dielectric constant was still high.
[0006]
Accordingly, it is an object of the present invention to provide a low-temperature fired porcelain having high mechanical strength and a wiring board using the same, as well as lowering the dielectric constant.
[0007]
[Means for Solving the Problems]
The present inventors have made extensive studies with respect to the object, the a SiO ₂ 35 ~ 40 mol% and _B 2 _{O 3} and 13-18 mol% and _Al 2 _{O 3} 7 to 12 mol% and MgO By firing a composition containing a glass component of 33 to 40 mol% and alumina, the dielectric strength in the high frequency region is made lower than 7.5 while increasing the bending strength of the resulting low-temperature fired ceramic. The present inventors have found that it is possible to achieve the present invention.
[0008]
That is, the low-temperature fired ceramic composition of the present invention, the SiO ₂ 35-40 mole% and _B 2 _{O 3} and 13 to 18 mol% and _Al 2 _{O 3} 7 to 12 mol% and MgO of 33 to 40 mol% Is contained in a proportion of 45 to 59% by volume of a glass component containing 99 mol% or more in total and 38 to 55% by volume of spherical alumina.
[0009]
The low-temperature fired ceramic of the present invention is characterized by firing the above-mentioned low-temperature fired ceramic composition at 850 to 1050 ° C.
[0010]
According to such a configuration, the relative permittivity of the low-temperature fired porcelain can be made lower than 7.5, and the use of such a low-temperature fired porcelain is sufficient to withstand unexpected drops and impacts when being carried. An insulating substrate having mechanical strength can be obtained.
[0011]
The low-temperature fired porcelain preferably contains at least cordierite and saphirin as crystal phases in the porcelain.
[0012]
By including at least cordierite and saphirin as crystal phases in the low-temperature fired porcelain, the relative dielectric constant at 1 GHz can be lowered, and the mechanical strength (bending strength) of the porcelain can be increased.
[0013]
In the low-temperature fired porcelain, when the (2 2 2) diffraction peak intensity of the cordierite in the X-ray diffraction measurement of the low-temperature fired porcelain is C and the (−2 5 2) diffraction peak intensity of the saphirin is S, S The peak ratio represented by / C is desirably 0.1 or more.
[0014]
In the relationship between cordierite and sapphirine formed in the low-temperature fired porcelain, the dielectric constant of the porcelain can be lowered and the mechanical strength can be further increased by increasing the generation ratio of saphirin.
[0015]
Wiring board of the present invention is the wiring board surface and / or inside the metallized wiring layer of an insulating substrate ceramic insulating layers are laminated in multiple layers are disposed, at least one layer of the ceramic insulating layers It consists of said low-temperature baking ceramics. By forming a wiring board using the low dielectric constant and high strength low-temperature sintered porcelain of the present invention, it is possible to form a wiring board having high transmission characteristics and excellent resistance to mounting and drop impact of products.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
The low-temperature fired ceramic of the present invention is composed of a glass component and a filler component as basic components.
[0017]
The glass component has a lower relative dielectric constant of itself , so that the glass component contains 35 to 40 mol% of SiO ₂ , 13 to 18 mol% of B ₂ O ₃ , and 7 to 12 of Al ₂ O _3. It is characterized by containing 99 mol% or more of mol% and MgO in a total amount of 33 to 40 mol%.
[0019]
Further, in the glass component constituting the low-temperature fired porcelain of the present invention, in addition to the above-mentioned SiO ₂ B ₂ O ₃ , Al ₂ O ₃ , and MgO, the dielectric constant and mechanical strength of the porcelain are not deteriorated. Impurities may be contained.
[0020]
The ratio of SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ and MgO contained in the glass component is limited to the above range because SiO ₂ is more than 40 mol% or B ₂ O ₃ is 18 mol. %, Al ₂ O ₃ is less than 7 mol%, or MgO is less than 33 mol%, the Young's modulus or strength of the glass tends to be low, and it is difficult to increase the strength of the porcelain. In addition, when SiO ₂ is less than 35 mol%, B ₂ O ₃ is less than 13 mol%, Al ₂ O ₃ is more than 12 mol%, or MgO is more than 40 mol%, the glass component This is because it is difficult to make the relative dielectric constant of porcelain lower than 7.5. In the latter case, vitrification tends to be difficult.
[0021]
In addition, as the total amount of SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ and MgO mainly constituting the glass component, the characteristics of the low-temperature fired ceramic according to the present invention that lower the relative dielectric constant and increase the mechanical strength are improved. It is desirable that the amount is 99 mol% or more, particularly 99.5 mol% or more. The glass component constituting the low-temperature fired porcelain of the present invention may contain inevitable impurities mixed in during the manufacturing process as long as it does not affect the dielectric constant and mechanical strength of the porcelain. .
[0022]
Further, the glass component other than the glass is preferably a glass having a relative dielectric constant lower than that of alumina. For example, borosilicate glass, quartz crystallized glass, cordierite crystallized glass, enstatite crystallized glass, forsterite Examples thereof include crystallized glass, mullite crystallized glass, diopside crystallized glass, and anorthite crystallized glass.
[0023]
Further, it is important that the low-temperature fired ceramic of the present invention contains alumina as a filler component. This is because, together with the glass component of the present invention, alumina having good wettability with the glass component and a relatively low dielectric constant and a high Young's modulus is contained, thereby suppressing the relative dielectric constant of the low-temperature fired ceramic porcelain of the present invention and Strength can be increased.
[0024]
In addition, the low-temperature fired ceramic composition of the present invention may contain other fillers in addition to the alumina. In this case, it is desirable that the metal oxide has a relative dielectric constant lower than that of alumina, for example, Quartz (SiO ₂ ), cordierite (2MgO · 2Al ₂ O ₃ · 5SiO ₂ ), enstatite (MgO · SiO ₂ ), forsterite (2MgO · SiO ₂ ), mullite (3Al ₂ O ₃ · 2SiO ₂ ), diopside Examples thereof include metal oxides such as (CaO · MgO · 2SiO ₂ ) and anorthite (CaO · Al ₂ O ₃ · 2SiO ₂ ). Among these, quartz and cordierite are desirable for reducing the dielectric constant of the porcelain.
[0025]
The low-temperature fired ceramic composition of the present invention contains 45 to 59 % by volume of the glass component and 38 to 55% by volume of alumina as a filler component for the purpose of obtaining a low dielectric constant and high strength. is Ru important. When the glass component is less than 45% by volume or the alumina is more than 55% by volume, the sinterability is lowered and only a porcelain with many voids is obtained, and the relative dielectric constant is also increased.
[0026]
On the other hand, when the glass component is more than 59 % by volume or alumina is less than 38 % by volume, the excess glass component makes it easy to melt at the time of firing, and the mechanical strength also decreases, and cracks occur in the mounting process. It becomes easy to do.
[0027]
As described above, in the low-temperature fired ceramic obtained from the low-temperature fired ceramic composition of the present invention in which the glass component and the alumina are configured in the above ratio, at least cordierite (2MgO · 2Al ₂ O ₃₎ is used as a crystalline phase. · 5SiO ₂₎ and / or sapphirine (it is desirable to contain the _{4MgO · 5Al 2 O 3 · 2SiO} 2), in particular, the low temperature sintering of ceramic of the cordierite in the X-ray diffraction measurement (2 2 2) diffraction When the peak intensity is C and the (−2 5 2) diffraction peak intensity of the saphirin is S, the peak ratio represented by S / C is preferably 0.1 or more, particularly 0.13 or more, It is more desirable that it is 0.17 or more, 0.21 or more, and further 0.33 or more.
[0028]
By including cordierite and / or sapphirine in the porcelain, the dielectric constant can be further lowered and the mechanical strength can be increased. As described above, since the relative permittivity of the porcelain can be reduced when the cordierite and sapphirine are precipitated in the porcelain, the average bending strength of the low-temperature fired porcelain is conventionally used. It can be equivalent to porcelain such as.
[0029]
In the low-temperature fired ceramic according to the present invention, the relative dielectric constant at 1 GHz can be lower than 7.5, and the mechanical strength can be increased to 280 MPa or more .
[0030]
In addition, the low-temperature fired porcelain of the present invention has a maximum diameter of 10 μm on the surface and / or inside of the porcelain because it increases the mechanical strength as described above and further improves the moisture resistance as a wiring board. It is desirable that the thickness be 5 μm or less. In the present invention, a low relative dielectric constant can be obtained and the strength can be increased even when densification is carried out by incorporating cordierite and sapphirine as crystal phases in the porcelain.
[0031]
Next, a method for producing the low-temperature fired porcelain of the present invention will be described.
[0032]
First, as a starting material, the glass powder as the glass component and the alumina powder as the filler component are mixed at the predetermined ratio described above according to the purpose such as the firing temperature and the thermal expansion coefficient.
[0033]
In the present invention, the average particle size of the glass powder applied to the porcelain is 0.1 to 5 μm, particularly 1 to 3 μm, because the maximum diameter of voids in the low-temperature fired porcelain is reduced and the sinterability is increased. The average particle size of the alumina powder is preferably 0.1 to 5 μm, particularly preferably 1 to 3 μm.
[0034]
In addition, when the glass powder used in the present invention does not add alumina as a filler powder, the firing shrinkage start temperature is 800 ° C. or lower and melts at 900 ° C. or higher, and a metallized wiring layer is disposed. I can't. However, by mixing alumina, crystal precipitation occurs in the firing process, and a liquid phase for liquid phase sintering of alumina can be formed at an appropriate temperature.
[0035]
Moreover, since the shrinkage start temperature of the whole compact can be raised, matching of the simultaneous firing conditions with the metallized wiring layer can be achieved by adjusting the content of the alumina powder depending on the type of metal used.
[0036]
Moreover, it is desirable that the blending amount of the alumina powder is appropriately adjusted according to the yield point of the glass powder. The yield point refers to the temperature at the center of the temperature range in which the glass melts rapidly and exhibits the largest volume change, and is usually 30 to 60 ° C. higher than the glass transition point. That is, when the yield point of the glass powder is as low as 550 to 700 ° C., the sinterability at a low temperature is enhanced, so that the amount of alumina can be blended relatively as high as 40 to 55% by volume. On the other hand, when the yield point of the glass powder is as high as 700 to 850 ° C., the sinterability is lowered. Therefore, it is desirable that the amount of alumina is relatively small as 38 to 50% by volume. The alumina used here is preferably a solid sphere for the reason of reducing the raw material cost of the filler powder.
[0037]
The low-temperature fired ceramic of the present invention is a mixture of the above glass powder and alumina containing at least one selected from the group consisting of chromium oxide, cobalt oxide, manganese oxide, nickel oxide, iron oxide and copper oxide as a coloring component. You may mix | blend in the ratio of 1 volume% or less with respect to 100 volume%.
[0038]
According to the present invention, an organic binder having an appropriate shape is added to the mixture of the glass powder and the alumina powder blended as described above, and then a desired forming means such as a doctor blade, a rolling method, and a die press. After forming into a predetermined shape, etc., firing is performed.
[0039]
In baking, the organic binder component mix | blended for shaping | molding is removed first. The removal of the organic binder is performed in an air atmosphere around 700 ° C. or in a nitrogen atmosphere. At this time, the shrinkage start temperature of the molded body is desirably about 700 to 850 ° C. If the shrinkage start temperature is lower than this, it becomes difficult to remove the organic binder. It is desirable to control the yield point as described above.
[0040]
Firing is performed in an oxidizing atmosphere at 850 ° C. to 1050 ° C. or in a non-oxidizing atmosphere. If the firing temperature at this time is lower than 850 ° C., it is difficult to densify, and if it exceeds 1050 ° C., simultaneous firing with a metallized wiring layer such as copper or silver becomes difficult when a wiring board described later is produced. In particular, it is desirable to bake in a temperature range of 900 to 1000 ° C., more preferably 900 to 975 ° C.
[0041]
That is, in the present invention, pores in the porcelain can be reduced by using a mixture of glass powder having an average particle diameter in the above range and alumina powder, and cordierite and / or in the porcelain. By depositing a specific low dielectric constant crystalline phase called safilin, a low dielectric constant and high strength low temperature fired ceramic can be obtained.
[0042]
FIG. 1 is a schematic cross-sectional view showing an embodiment of a wiring board, in particular, a BGA type semiconductor element housing package and its mounting structure, as an application example of the low-temperature fired porcelain of the present invention. This package has a basic structure of a so-called wiring board in which a metallized wiring layer is disposed on the surface or inside of an insulating board, A is a package for housing a semiconductor element, and B is an external circuit board.
[0043]
The semiconductor element storage package A includes an insulating substrate 1, a lid 2, a metallized wiring layer 3, and connection terminals 4, and the insulating substrate 1 and the lid 2 have a cavity 6 for accommodating the semiconductor element 5 in an airtight manner. Form. In the cavity 6, the semiconductor element 5 is bonded and fixed to the insulating substrate 1 through an adhesive such as glass or resin.
[0044]
A metallized wiring layer 3 is disposed on the surface and inside of the insulating substrate 1 so as to be electrically connected to the semiconductor element 5 and the connection terminal 4 formed on the lower surface of the insulating substrate 1. ing. According to the package of FIG. 1, the connection terminal 4 has a ball-shaped terminal 4b made of high-melting-point solder (tin-lead alloy) attached through a connection pad 4a with a brazing material.
[0045]
On the other hand, the external circuit board B is composed of an insulator 7 and a wiring conductor 8, and the insulator 7 is made of an insulating material containing at least an organic resin, specifically, a glass-epoxy composite material or the like. The linear thermal expansion coefficient of 40 to 400 ° C. is 12 to 16 × 10 ⁻⁶ / ° C., and a printed circuit board or the like is generally used. In addition, the wiring conductor 8 formed on the surface of the substrate B is usually Cu, Au, Ag, Al, Ni, Pb in terms of the consistency of the thermal expansion coefficient with the insulator 7 and good electrical conductivity. -It consists of metal conductors, such as Sn.
[0046]
In order to mount the semiconductor element housing package A on the external circuit board B, the ball-like terminals 4b on the lower surface of the insulating substrate 1 of the package A are placed on and contacted with the wiring conductors 8 of the external circuit board B, Mounting is performed by melting the solder at a temperature of about 250 to 400 ° C. with a soldering material such as solder having a melting point and joining the wiring conductor and the ball-shaped terminal 4 b. At this time, it is desirable that a brazing material is previously formed on the surface of the wiring conductor 8 in order to easily connect the ball terminal 4b with the brazing material.
[0047]
According to the present invention, a multilayer wiring board constituted by using a low-temperature fired porcelain having high strength and low dielectric constant is excellent in mechanical characteristics and high in reliability as the multilayer wiring board such as alumina conventionally used. It is useful and has excellent dielectric characteristics, and can suppress signal attenuation due to dielectric loss even when handling high-frequency signals.
[0048]
【Example】
Hereinafter, the low-temperature fired porcelain of the present invention and a wiring board using the same will be described in detail based on examples. First, two types of glass powders shown in Table 1 were prepared as glass powders, and alumina powder and quartz were prepared as fillers, and weighed and mixed so that the ratios shown in Table 2 were obtained. The average particle size of the glass powder was 3 μm, and the average particle size of alumina and quartz was 1 μm.
[0049]
Next, after pulverizing this mixture, an organic binder and an organic solvent were added and mixed well to prepare a slurry, and a green sheet having a thickness of 300 μm was prepared by a doctor blade method.
[0050]
After the obtained green sheets and 15 sheets were laminated and pressure-bonded, samples of 60 mm × 60 mm × 2.4 mm and 5.5 mm × 60 mm × 4.5 mm were prepared and placed in a nitrogen atmosphere containing 700 ° C. water vapor. After the binder removal treatment, firing was performed in a nitrogen atmosphere having a firing temperature × 1 hour shown in Table 2.
[0051]
Next, the relative dielectric constant and three-point bending strength at 1 GHz were measured for the low-temperature fired ceramics obtained as described above. Moreover, X-ray diffraction measurement was performed on this low-temperature fired ceramic, and the crystal phase was identified from the X-ray diffraction pattern. Further, for the sample in which cordierite and sapphirine were detected, the ratio S / C between the intensity C of cordierite (222) diffraction peak and the intensity S of saphirin (−25 2) diffraction peak was determined. The results are shown in Table 2.
[0052]
[Table 1]

[0053]
[Table 2]

[0054]
As is apparent from the results in Table 2, the sample No. 2～8,11, in 14, both the relative dielectric constant at 1GHz as low as 7.3 or less, and flexural strength was as high as 280 MPa or more. For this, the sample No. of the present invention was baked at 900 to 975 ° C. In each of 3 to 8 and 14, cordierite and sapphirine are detected, the peak intensity ratio S / C in the X-ray diffraction is 0.17 or more, the relative dielectric constant at 1 GHz is 7 or less, and the bending strength is 285 MPa. It was done above. In particular, sample no. 6 and 7, the peak intensity ratio S / C in X-ray diffraction was 0.33 or more, the relative dielectric constant could be further lowered to 6.9 or less, and the mechanical strength could be increased to 315 MPa or more. .
[0055]
Meanwhile, sample no. In 1, 9, 10, 12, 13 , and 15 , the sintered porcelain was unsintered or oversintered. Alternatively, only a high dielectric constant or a low bending strength was obtained.
[0056]
【The invention's effect】
As described above in detail, in the low-temperature fired ceramic composition and low-temperature fired ceramic of the present invention, a glass component containing SiO ₂ , B ₂ O ₃ , Al ₂ O _3, and MgO as main components and alumina at a predetermined ratio. By combining them, the dielectric constant of the porcelain can be reduced. In particular, by including at least cordierite and / or sapphirine in the porcelain, a low dielectric constant and high strength can be achieved.
[0057]
As described above in detail, in the low-temperature fired ceramic composition of the present invention, by combining a glass component containing alumina, SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ and MgO as main components with alumina in a predetermined ratio, The relative dielectric constant at 1 GHz of the obtained low-temperature fired ceramic can be made lower than 7.5, and the mechanical strength can be increased to 280 MPa or more. In particular, by including at least cordierite and / or sapphirine in the low-temperature fired ceramic, it is possible to further reduce the dielectric constant and increase the strength.
[Brief description of the drawings]
1 is a schematic cross-sectional view for explaining an embodiment of a wiring substrate of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Insulation board | substrate 2 Cover body 3 Metallized wiring layer 4 Connection terminal 4a Electrode pad 4b Ball-shaped terminal 5 Semiconductor element 6 Cavity 7 Insulator 8 Wiring conductor 9 Electrode layer 10 Via-hole conductor A Package for semiconductor element storage B External electric circuit board

Claims (5)

A glass component containing 35 to 40 mol% of SiO ₂ , 13 to 18 mol% of B ₂ O ₃ , 7 to 12 mol% of Al ₂ O ₃ and 33 to 40 mol% of MgO in a total amount of 99 mol% or more. A low-temperature-fired porcelain composition containing 45 to 59% by volume and spherical alumina in a proportion of 38 to 55% by volume.   A low-temperature fired ceramic made by firing the low-temperature fired ceramic composition according to claim 1 at 850 to 1050 ° C.   The low-temperature-fired porcelain according to claim 2, wherein the crystal phase contains at least cordierite and saphirin.   In the X-ray diffraction measurement, when the (2 2 2) diffraction peak intensity of the cordierite is C and the (−25 2) diffraction peak intensity of the saphirin is S, the peak ratio represented by S / C is 0. The low-temperature fired porcelain according to claim 3, wherein the number is one or more.   5. A wiring board in which a metallized wiring layer is disposed on the surface and / or inside of an insulating board in which ceramic insulating layers are laminated in multiple layers, and at least one of the ceramic insulating layers is any one of claims 2 to 4. A wiring board comprising the low-temperature fired porcelain described in 1.

Images