JP4166731B2 - Low temperature fired substrate material and multilayer wiring board using the same - Google Patents

Description

  The present invention relates to a glass-ceramic substrate composed of a glass component and a ceramic component, that is, a low-temperature fired substrate material, and a multilayer wiring substrate using the same.

Disclosure of technology related to glass-ceramic substrates (low temperature fired substrates, LTCC substrates) that can be fired at a low temperature of 1000 ° C. or lower in order to perform simultaneous firing with a conductor material and a resistance material in an insulating wiring substrate for semiconductor chips. (For example, refer to Patent Document 1 or Patent Document 2). This substrate is obtained by first forming a green sheet, printing a wiring with a conductive material or a resistance material on the surface, laminating and pressing a plurality of sheets, and firing the laminated body. Configure the substrate. This substrate is used as an LTCC module such as a high frequency superposition module, an antenna switch module, or a filter module.
JP-A-1-132194 Japanese Patent Laid-Open No. 5-21006

  In recent years, in order to increase production efficiency, firing is often performed in the form of a collective substrate so that a plurality of products can be obtained from one substrate. At this time, in order to maintain the accuracy of the product obtained from the collective substrate, the flatness of the collective substrate is increasingly required.

  At the same time, in order to increase the integration and miniaturization of LTCC modules, not only a multilayer wiring board in which glass-ceramic mixed layers having the same dielectric constant are stacked, but also glass-ceramic mixed layers having different relative dielectric constants are stacked. It is desired to form a multilayer wiring board.

  However, when glass / ceramic mixed layers of different compositions are laminated to make a difference in relative dielectric constant to form a multilayer wiring board, the linear thermal expansion coefficient of the glass / ceramic mixed layers of different compositions also differs. This causes a problem of warping.

  In order to solve the problem of warpage of the fired product, the difference in the linear thermal expansion coefficient is canceled and the warp of the fired product is prevented by making the green sheet a symmetrical structure in the stacking direction. . However, in order to improve the degree of freedom of design and flexibly respond to demand demands, it is desired that the warp is small even without taking a symmetrical structure.

Therefore, the first object of the present invention is to have a linear thermal expansion coefficient of 5.90 × 10 ^{−6 to} 6.40 × 10 ⁻⁶ / ° C., which is similar to that of a conventional low-temperature fired substrate material. On the other hand, it is to provide a low-temperature fired substrate material having a dielectric constant as high as 10 or more. By including a high-capacitance capacitor layer in the multilayer wiring board, the module can be made thinner and smaller. Furthermore, a second object of the present invention is to provide a multilayer wiring board in which glass-ceramic mixed layers of different compositions are laminated for improving the degree of freedom in design, and warps of the fired product even if the laminated structure is not symmetrical. To make it smaller.

The present inventors have found that cordierite can be contained as a filler, and that the linear thermal expansion coefficient of the low-temperature fired substrate material can be easily controlled by increasing or decreasing the content thereof, thereby completing the present invention. . That is, the low-temperature fired substrate material according to the present _invention, SiO 2 46 to 60 _{wt%, B} 2 O 3 0.5 to 5 _{wt%, Al} 2 O 3 6 to 17.5 wt% and an alkaline earth metal oxide 60-78 vol% glass having a composition of 25-45 wt%, wherein at least 60 wt% of the alkaline earth metal oxide is SrO, 14-27 vol% titania, and 5 to 5 cordierite containing 15.5Vol%, and, in linear thermal expansion coefficient at 50 to 300 ° C. is ^{5.90 × 10 -6 /℃~6.40×10 -6 / ℃} , the relative dielectric constant at room temperature 1.9GHz It is characterized by being 10 or more. As disclosed in Patent Document 2, as a substrate material having a high relative dielectric constant, a material composed of glass and filler, in which the filler is composed of titania and alumina, is known. Titania is added to increase the dielectric constant, and alumina is added to adjust the dielectric constant. However, since titania and alumina both have a large coefficient of linear thermal expansion, a multilayer wiring board in which a glass-ceramic mixed layer containing titania and alumina is laminated with a glass-ceramic mixed layer of a different composition having a low linear thermal expansion coefficient is sintered. Sometimes warps. In order to reduce this warpage, it is conceivable to reduce the content of titania having a large linear thermal expansion coefficient, but this is not preferable because the high dielectric constant characteristic of titania is lost. Therefore, the present inventors do not contain alumina having a high linear thermal expansion coefficient like titania, and by adding cordierite having a low linear thermal expansion coefficient, the linear thermal expansion coefficient is maintained while maintaining a high relative dielectric constant. Succeeded in controlling. With the low-temperature fired substrate material according to the present invention, the linear thermal expansion coefficient can be easily controlled by increasing or decreasing the cordierite content.

The multilayer wiring board according to the present invention is a multilayer wiring board in which glass-ceramic mixed layers are laminated. At least one of the glass-ceramic mixed layers is composed of 46 to 60% by weight of SiO ₂ and B ₂ O ₃ 0. .5～5 _{wt%, Al} 2 O 3 has a composition of from 6 to 17.5% by weight and an alkaline earth metal oxide 25-45 wt%, at least 60% by weight of the alkaline earth metal oxide is The glass which is SrO contains 60 to 78 vol%, titania 14 to 27 vol% and cordierite 5 to 15.5 vol%, and the linear thermal expansion coefficient at 50 to 300 ° C. is 5.90 × 10 6. in ^{-6 /℃~6.40×10 -6} / ℃, characterized in that it consists of low-temperature fired substrate material is 10 or more relative dielectric constant at room temperature 1.9 GHz. Temperature fired substrate material according to the present invention, while having a high dielectric constant, since the linear thermal expansion coefficient can be controlled with 5.90 × ^{10 -6} /℃~6.40×10 ^-6 / ℃ For example, when combined with a low-dielectric constant low-temperature fired substrate material, the linear thermal expansion coefficient can be matched to reduce warpage.

In the multilayer wiring board according to the present invention, a wire at 50 to 300 ° C. of the glass-ceramic mixed layer made of the low-temperature fired substrate material according to the present invention and another glass-ceramic mixed layer other than the glass-ceramic mixed layer. The difference in thermal expansion coefficient is preferably 0.25 × 10 ⁻⁶ / ° C. or less. Warpage can be reduced by controlling the difference in linear thermal expansion coefficient within the above range.

  In the multilayer wiring board according to the present invention, the other glass-ceramic mixed layer preferably has a relative dielectric constant of 5 to 8 at a room temperature of 1.9 GHz. A multilayer wiring board can be formed by laminating glass-ceramic mixed layers having different relative dielectric constants, and the LTCC module can be highly integrated and miniaturized.

In the multilayer wiring board according to the present invention, the other glass-ceramic mixed layer is specifically composed of 46 to 60% by weight of SiO ₂ , 0.5 to 5% by weight of B ₂ O ₃ , Al ₂ O ₃ 6. 58 to 76 vol% of glass having a composition of ˜17.5 wt% and alkaline earth metal oxide of 25 to 45 wt%, wherein at least 60 wt% of the alkaline earth metal oxide is SrO, and A glass-ceramic mixed layer made of a low-temperature fired substrate material containing 24 to 42 vol% of alumina is preferable.

  Further, in the multilayer wiring board according to the present invention, the occurrence of warpage is suppressed by reducing the difference in coefficient of linear thermal expansion between the glass-ceramic mixed layers, but the warpage is 200 μm or less per 50 mm square size. Is included. Furthermore, the case where the curvature is 200 μm or less per 100 mm square is included.

  The present invention includes a cordierite as a filler for controlling the linear thermal expansion coefficient in a low-temperature fired substrate material, thereby preventing high-expansion porcelain and having a high relative dielectric constant. It can be. Further, according to the present invention, in a multilayer wiring board in which glass-ceramic mixed layers having different compositions are laminated, the warp of the fired product can be reduced without making the laminated structure symmetrical. Thus, by placing a high-capacitance capacitor layer in the multilayer wiring board, the degree of freedom in design can be improved while the module is reduced in thickness and size.

  Hereinafter, although an embodiment is shown to the present invention and the present invention is explained in detail, the present invention is limited to these descriptions and is not interpreted.

The low-temperature fired substrate material according to the present embodiment includes 60 to 78 vol% glass component and 22 to 40 vol% ceramic component, that is, titania (TiO ₂ ) and cordierite (Mg ₂ Al ₄ Si ₅ O ₁₈ ). It consists of ceramic components.

Here, the glass is composed of 46 to 60% by weight of SiO ₂ , preferably 47 to 55% by weight, 0.5 to 5% by weight of B ₂ O ₃ , preferably 1 to 4% by weight, and _{6 to} 17.5 Al ₂ O ₃ . It is necessary to have a composition of wt%, preferably 7 to 16.5 wt% and alkaline earth metal oxide 25 to 45 wt%, preferably 30 to 40 wt%. If this SiO ₂ is less than 46% by weight, vitrification becomes difficult, and if it exceeds 60% by weight, the glass softening point becomes too high and low-temperature sintering becomes impossible. Further, if B ₂ O ₃ is more than 5% by weight, the moisture resistance after sintering is lowered, and if it is less than 0.5% by weight, the vitrification temperature is slightly increased and the sintering temperature is increased. Since it becomes too high, it is not preferable. Further, if Al ₂ O ₃ is less than 6% by weight, the strength of the glass component is lowered, and if it exceeds 17.5% by weight, vitrification becomes difficult. As the alkaline earth metal oxide in the glass component, there are MgO, CaO, BaO and SrO, but it is necessary that at least 60% by weight, preferably 80% by weight or more of the total amount is SrO. If this amount is less than 60% by weight, the glass softening point becomes high and low-temperature firing becomes difficult. And by adding some of other CaO, MgO, BaO in combination, the viscosity of the molten glass can be reduced, the sintering temperature range can be expanded, and the production becomes easy. Is preferred. In terms of the effect of addition, CaO, MgO, and BaO in the alkaline earth metal oxide are preferably combined in an amount of 1% by weight or more, and CaO and MgO are each 0.2% by weight or more, particularly 0.5%. It is preferable to make it at least wt%. The CaO in the alkaline earth metal oxide is preferably less than 10% by weight, and MgO is preferably 6% by weight or less. If the amount of these oxides is larger than that, a high-strength porcelain cannot be obtained, and it becomes difficult to control the crystallinity of the glass.

  In the low-temperature fired substrate material according to the present embodiment, the glass component is preferably 60 to 78 vol%. When the glass component is less than 60 vol%, that is, when the ceramic component exceeds 40 vol%, a dense sintered body at 1000 ° C. or less cannot be obtained. On the other hand, when the glass component exceeds 78 vol%, that is, when the ceramic component is less than 22 vol%, the bending strength decreases.

  The content of titania, which is one of the ceramic components, is preferably 14 to 27 vol%. Titania is added to increase the relative dielectric constant, and if it is less than 14 vol%, the relative dielectric constant is low. On the other hand, if it is added over 27 vol%, the linear thermal expansion coefficient of the low-temperature fired substrate material becomes too large.

The content of cordierite that is one of the ceramic components is preferably 5 to 15.5 vol%. Cordierite has a low linear thermal expansion coefficient of 50 to 300 ° C. as 1.8 × 10 ⁻⁶ / ° C. and a relative dielectric constant as low as 4.8. Therefore, by changing the content in the low-temperature fired substrate material, it is possible to control the linear thermal expansion coefficient to be lowered without greatly affecting the relative dielectric constant. When the cordierite content is less than 5 vol%, the linear thermal expansion coefficient of the low-temperature fired substrate material becomes large. On the other hand, when the cordierite content exceeds 15.5 vol%, the linear thermal expansion coefficient of the low-temperature fired substrate material becomes too small. .

The low-temperature fired substrate material according to the present embodiment has a linear thermal expansion coefficient of 5.90 × 10 ^{−6 to} 6.40 × 10 ⁻⁶ / ° C. at 50 to 300 ° C. and room temperature of 1 by adjusting each component. The relative dielectric constant at 9 GHz is preferably 10 or more. In particular, the linear thermal expansion coefficient is controlled by cordierite. As a low-temperature fired substrate material, it is possible to provide a material having a high relative dielectric constant while suppressing high linear thermal expansion.

  The low-temperature fired substrate material of the present embodiment may contain other components as long as the object of the present invention is not violated.

  Only the glass-ceramic mixed layer made of the low-temperature fired substrate material according to the present embodiment may be laminated to form a multilayer wiring board. However, in the present embodiment, at least one of the glass-ceramic mixed layers as shown in FIG. Is made of the low-temperature fired substrate material according to the present embodiment, and a multilayer wiring substrate can be formed by laminating glass-ceramic mixed layers having different compositions. FIG. 1 shows a schematic cross-sectional view of a multilayer wiring board. The laminated structure shown by (a) to (e) in (1) and (a) to (e) in (2) is a specific example in the case where glass-ceramic mixed layers having different compositions are laminated in an asymmetric structure. The laminated structures shown in (a) to (e) of (3) are specific examples in the case where glass-ceramic mixed layers having different compositions are laminated in a symmetrical structure. FIG. 1 shows a case where a multilayer wiring board is obtained by laminating glass-ceramic mixed layers having two compositions. For example, the glass-ceramic mixed layer shown by hatched portions is made of the low-temperature fired substrate material according to the present embodiment. The glass-ceramic mixed layer shown by the white part without the mark is made of another low-temperature fired substrate material. In addition, it is good also as a multilayer wiring board which consists of a glass-ceramics mixed layer of 3 or more types of different compositions.

The low-temperature fired substrate material according to the present embodiment has a linear thermal expansion coefficient of 5.90 × 10 ^{−6 to} 6.40 × 10 ⁻⁶ / ° C. at 50 to 300 ° C., and a relative dielectric constant of 10 or more at a room temperature of 1.9 GHz. However, when a multilayer substrate is combined with a glass-ceramic mixed layer of another composition, the difference in linear thermal expansion coefficient at 50 to 300 ° C. between the glass-ceramic mixed layers is 0.25 × 10 ⁻⁶ / ° C. By making the following, it is possible to suppress warping of the collective substrate. Warpage is indicated by w in FIG. By setting the difference in linear thermal expansion coefficient of each laminated glass-ceramic mixed layer to 0.25 × 10 ⁻⁶ / ° C. or less, the warp W of the multilayer wiring board is 200 μm or less per 50 mm square size, Alternatively, it can be 200 μm or less per 100 mm square size. At this time, assuming that the length of one side of the substrate (long side when there is a long side and a short side) is t, the warpage rate obtained by w / t is 0.4% or less, preferably 0.2% or less. it can.

When the difference in linear thermal expansion coefficient exceeds 0.25 × 10 ⁻⁶ / ° C., for example, a laminated structure shown in (a) to (e) of FIG. The glass-ceramic mixed layer must be arranged so as to be symmetric at the center in the stacking direction. However, in the multilayer wiring board according to the present embodiment, the difference in coefficient of linear thermal expansion can be controlled within 0.25 × 10 ⁻⁶ / ° C. depending on the cordierite content, so that (a) in FIG. Even when laminated in an asymmetric structure like the laminated structures shown in (a) to (e) of (e) and (2), the warp can be kept small.

  Furthermore, if the relative dielectric constant at room temperature 1.9 GHz of another glass-ceramic mixed layer made of materials other than the low-temperature fired substrate material according to the present embodiment is 5 to 8, the difference in relative dielectric constant should be at least 2 or more. Therefore, the degree of freedom in substrate design is further increased.

For example, the glass-ceramic mixed layer made of the low-temperature fired substrate material described in Patent Document 1 can be selected as another glass-ceramic mixed layer made of other than the low-temperature fired substrate material according to the present embodiment. The low-temperature fired substrate material described in Patent Document 1 has a linear thermal expansion coefficient at 50 to 300 ° C. of 5.90 × 10 ^{−6 to} 6.40 × 10 ⁻⁶ / ° C., and a relative dielectric constant at a room temperature of 1.9 GHz is 5-8. Therefore, it is suitable for forming a multilayer substrate in combination with the low-temperature fired substrate material according to the present invention. The low-temperature fired substrate material described in Patent Document 1 is composed of 46 to 60% by weight of SiO ₂ , 0.5 to 5% by weight of B ₂ O ₃ , _{6 to} 17.5% by weight of Al ₂ O _3, and alkaline earth metal oxide 25. The glass has a composition of ˜45% by weight, 58% to 76% by volume of glass in which at least 60% by weight of the alkaline earth metal oxide is SrO, and 24 to 42% by volume of alumina as a filler. The reason why the glass component is 58 to 76 vol% is that the glass is not fired if it is less than 58 vol%, and the bending strength is lowered if it exceeds 76 vol%.

When the glass-ceramic mixed layer made of the low-temperature fired substrate material described in Patent Document 1 is used as the other glass-ceramic mixed layer, the difference in linear thermal expansion coefficient between the layers at 50 to 300 ° C. is 0.25 × 10 ^−6. Glass-ceramics made of the low-temperature fired substrate material according to the present embodiment in order to set the difference in relative dielectric constant between layers to 2 or more, more preferably within 0.10 ° C., and more preferably 0.10 × 10 ⁻⁶ / ° C. In the mixed layer, the content of titania, which is one of the ceramic components, is preferably 14 to 27 vol%, more preferably 15 to 25 vol%. Furthermore, the content of cordierite which is one of ceramic components is preferably 5 to 15.5 vol%, more preferably 5 to 13 vol%. The glass component is 60 to 78 vol%, more preferably 62 to 78 vol%. Wherein the composition of the glass, _preferably, SiO 2 _47-55% by weight, _{B 2} O 3 1 to 3 _{wt%, Al} 2 O 3 7 to 16.5% by weight and an alkaline earth metal oxide 30-40 wt %.

  The glass-ceramic mixed layer other than the glass-ceramic mixed layer made of the low-temperature fired material according to the present invention is formed of at least one layer using, for example, the low-temperature fired substrate material related to the wiring board described in Patent Document 1. Preferably, all other glass-ceramic mixed layers are formed of a low-temperature fired substrate material according to the wiring substrate described in Patent Document 1.

  In order to manufacture the multilayer wiring board of the present embodiment, for example, the ceramic component and glass component raw materials are mixed as a powder having an average particle size of 10 μm or less, preferably 1 to 4 μm, respectively, and water or a solvent and necessary A paste is prepared by adding an appropriate binder accordingly. Next, this paste is formed into a sheet having a thickness of about 0.1 to 1.0 mm using a doctor blade, an extruder or the like to obtain a ceramic green sheet. A plurality of the ceramic green sheets are laminated and pressed in a heated state at 40 to 120 ° C. to obtain a laminated body. This laminate is simultaneously sintered at 800 to 1000 ° C. Thereby, a multilayer substrate is obtained. Alternatively, the powdery mixture of each component may be dry-pressed as it is to form a sheet, a plurality of these are laminated, then pressed to obtain a laminate, and this may be sintered. At this time, a multilayer wiring board may be formed by applying a conductor, a resistor, an overcoat, a thermistor, and the like and firing them simultaneously.

Next, the present invention will be described in more detail with reference to examples. Each powder of glass, titania and cordierite was mixed with a ball mill for 16 hours so that the composition shown in Table 1 was obtained, and the resulting mixed powder (average particle size 1.5 μm) was mixed with an organic solvent such as toluene and ethanol, and A paint is obtained by adding a binder to form a paste. Here, the composition of the glass was 50 wt% SiO ₂ +2 wt% B ₂ O ₃ +11 wt% Al ₂ O ₃ +1 wt% MgO + 3 wt% CaO + 33 wt% SrO in terms of oxide. Using this paint, a ceramic green sheet was formed by the doctor blade method. The thickness of the ceramic green sheet was adjusted to 80 μm after firing. Six layers of this ceramic green sheet were laminated, then pressed and fired at 850 to 950 ° C. for 2 hours. As a result, a multilayer substrate having a thickness of 480 μm and a single composition was obtained. Table 1 shows the relative dielectric constant εr, Q (1 / tan δ) at room temperature of 1.9 GHz, linear thermal expansion coefficient α and bending strength at 50 to 300 ° C. of the obtained multilayer substrate. The relative dielectric constant and tan δ were measured by the perturbation method using a device name network analyzer model number HP8510C manufactured by HEWLETT PACKARD. The linear thermal expansion coefficient was measured using a device name DILATOMETER model number 5000 manufactured by MAC. The bending strength was determined by a three-point bending method using a device name Universal Material Testing Machine Model No. 5543 manufactured by INSTRON.

(Control of coefficient of linear thermal expansion by adding cordierite-part 1)
First, as shown by Comparative Example 1 and Comparative Example 2 and Examples 1 to 3, titania was replaced with cordierite, that is, composition formula 0.60 glass + (0.40−x) TiO 2. _{In 2} + xMg ₂ Al ₄ Si ₅ O ₁₈ , when x is changed, the linear thermal expansion coefficient changes as shown in FIG. 3, and the relative dielectric constant changes as shown in FIG. Further, as shown by Comparative Example 4, Comparative Example 5 and Examples 8 to 11, when titania is replaced with cordierite, that is, composition formula 0.78 glass + (0.22-x) TiO. _{In 2} + xMg ₂ Al ₄ Si ₅ O ₁₈ , when x is changed, the linear thermal expansion coefficient changes as shown in FIG. 5, and the relative dielectric constant changes as shown in FIG. Cordierite has a linear thermal expansion coefficient of 1.8 × 10 ⁻⁶ / ° C. and a relative dielectric constant of 4.8 at 50 to 300 ° C., while titania has a linear thermal expansion coefficient of 11 at 50 to 300 ° C. 5 × 10 ⁻⁶ / ° C. and a relative dielectric constant of 104. Therefore, when the substitution amount for replacing titania with cordierite is increased, the linear thermal expansion coefficient decreases according to the addition amount as shown in FIGS. 3 and 5, and the relative dielectric constant is reduced as shown in FIGS. Decreases according to the amount added. However, when cordierite is added in the range of FIG. 4, the relative permittivity is 13.5 or more, and when cordierite is added in the range of FIG. 6, the relative permittivity is 10.5 or more. In either case, a relative dielectric constant of 10 or more can be secured. Therefore, it has been clarified that by replacing titania with cordierite, the low-temperature fired substrate material can be controlled so as to reduce the linear thermal expansion coefficient while having a relative dielectric constant of 10 or more.

From the above, it has been clarified that the coefficient of linear thermal expansion can be controlled by adding cordierite, but it must be fired as a low-temperature fired substrate, and even if fired, it must have a bending strength of a predetermined level or higher. is there. Furthermore, the linear thermal expansion coefficient at 50 to 300 ° C. is required to be 5.90 × 10 ^{−6 to} 6.40 × 10 ⁻⁶ / ° C., and the relative dielectric constant at room temperature 1.9 GHz is required to be 10 or more. . Comparative Example 4 contains only 4 vol% cordierite, and the linear thermal expansion coefficient is too high at 6.44 × 10 ⁻⁶ / ° C. In Comparative Example 2, cordierite is as high as 16 vol%, and the linear thermal expansion coefficient is too low at 5.87 × 10 ⁻⁶ / ° C. Since Comparative Example 1 has a high titania content of 28 vol%, the thermal expansion coefficient is as high as 6.42 × 10 ⁻⁶ / ° C. Comparative Example 3 was not fired because the glass component contained only 58 vol%. Since the comparative example 5 contains only 13 vol% of titania, the linear thermal expansion coefficient is too low at 5.78 × 10 ⁻⁶ / ° C. Since the comparative example 6 contains 80 vol% of glass components, the bending strength is low.

(Preliminary examination of warpage of different composition multilayer substrate)
Two types of ceramic green sheets with different compositions are each formed into a 10 mm square, and a laminated body is formed so as to form a laminated structure of 6 layers, and then fired at the same time. A multilayer substrate made of Here, the composition of one glass-ceramic mixed layer is 70 vol% glass-30 vol% alumina (referred to as S composition), and the composition of the other glass-ceramic mixed layer is 70 vol% glass-15 vol% alumina-15 vol% titania. (Denoted as T composition). Here, the composition of each glass was 50 wt% SiO ₂ +2 wt% B ₂ O ₃ +111 wt% Al ₂ O ₃ +1 wt% MgO + 3 wt% CaO + 33 wt% SrO in terms of oxide. The multilayer structure of the multilayer substrate was the multilayer structure shown in FIGS. The magnitude (average value) of warping at that time is shown in FIG. Referring to FIG. 7, the warp is the largest in the laminated structure shown in (d), which is the most asymmetrical structure, and the warped in the laminated structure shown in (a) and (g), which is a multilayer substrate made of only the same composition. Is the smallest.

  From the results shown in FIG. 7, since it was confirmed that the multilayer structure of (c) is the most asymmetric structure among the multilayer substrates having the multilayer structure of (a) to (e) of FIG. The laminated structure shown in FIG. 1C was evaluated. This is because if the warp can be reduced in the stacked structure of FIG. 1C, the warp is reduced in other stacked structures.

(Examination of warpage of multilayer substrate with different composition)
Two types of ceramic green sheets having different compositions are respectively formed, and a laminated body is formed so as to have a laminated structure of 6 layers shown in FIG. 1 (c), and then subjected to simultaneous firing, whereby a thickness of 6 layers is 480 μm. A multilayer substrate comprising glass-ceramic mixed layers having different compositions was prepared. Three levels of the multilayer substrate were prepared: 10 mm square, 50 mm square, and 100 mm square. Here, the composition of one glass-ceramic mixed layer was set to each composition shown in Table 1. The composition of the other glass-ceramic mixed layer was a glass-ceramic mixed layer containing 70 vol% glass and 30 vol% alumina. Here, in any glass-ceramic mixed layer, the composition of the glass is 50 wt% SiO ₂ +2 wt% B ₂ O ₃ +111 wt% Al ₂ O ₃ +1 wt% MgO + 3 wt% CaO + 33 wt% in terms of oxide. SrO. The other glass-ceramic mixed layer had a linear thermal expansion coefficient α at 50 to 300 ° C. of 6.15 × 10 ⁻⁶ / ° C. and a relative dielectric constant of 7.3.

Table 2 summarizes the linear thermal expansion coefficient α of the glass-ceramic mixed layer at 50 to 300 ° C., the amount of warpage of each of the 10 mm square, 50 mm square, and 100 mm square multilayer substrates, and the warpage evaluation of the multilayer substrate. In the evaluation of the warpage of the multilayer substrate, a sample in which the warpage of a 50 mm square substrate was 200 μm or less was evaluated as “◯”, and the case where it exceeded 200 μm was evaluated as “X”. Further, whether or not the relative dielectric constant difference between the glass-ceramic mixed layers was equal to or greater than a predetermined value was added to the evaluation of the multilayer substrate. When the warpage of the 50 mm square substrate is 200 μm or less, the relative dielectric constant of one glass-ceramic mixed layer is 10 or more, and the bending strength in Table 1 is 190 MPa or more, the multilayer substrate is A comprehensive evaluation (circle) was given, the case where it was not satisfied was set as x, and the results are shown in Table 2.

From the results of Table 2, it can be seen that the smaller the difference in the coefficient of linear thermal expansion between the other glass-ceramic mixed layer and the one glass-ceramic mixed layer, the smaller the warp of the substrate. The linear thermal expansion coefficient at 50 to 300 ° C. of the other glass-ceramic mixed layer is 6.15 × 10 ⁻⁶ / ° C., whereas the linear heat at 50 to 300 ° C. of one glass-ceramic mixed layer. When the expansion coefficient is 5.90 × 10 ^{−6 to} 6.40 × 10 ⁻⁶ / ° C., the warpage of the substrate is small. That is, if the difference in linear thermal expansion coefficient is within 0.25 × 10 ⁻⁶ / ° C., the warpage of the 50 mm square substrate can be reduced to 200 μm or less. More preferably, by setting the difference in linear thermal expansion coefficient to be within 0.1 × 10 ⁻⁶ / ° C., the warpage of the 50 mm square substrate becomes 100 μm. More preferably, by setting the difference in coefficient of linear thermal expansion within 0.05 × 10 ⁻⁶ / ° C., the warpage of a 100 mm square substrate becomes 200 μm or less. Comparative Examples 1, 2, 4, and 5 have large differences in linear thermal expansion coefficients and large warpage. In Comparative Example 3, a fired body cannot be obtained. In Comparative Example 6, since the bending strength of one glass-ceramic mixed layer is small, it is considered that the bending strength of the multilayer substrate itself is also small. As shown in the examples, a multilayer substrate having a small warpage and a glass-ceramic mixed layer having different dielectric constants could be produced. As a result, a high-capacity capacitor layer is placed in the multilayer wiring board while maintaining accuracy, and the degree of freedom in design can be improved while reducing the thickness and size of the module.

The cross-sectional schematic diagram of a multilayer wiring board is shown, and the laminated structure shown by (a) to (e) in (1) and (a) to (e) in (2) is asymmetric with a glass-ceramic mixed layer of different composition It is a specific example in the case of being laminated in a structure, and the laminated structure shown by (a) to (e) in (3) is a specific example in the case where glass-ceramic mixed layers having different compositions are laminated in a symmetric structure. It is the schematic which shows the measurement location when calculating | requiring the curvature amount of a board | substrate. In the composition formula 0.60 glass _{+ (0.40-x) TiO 2} + xMg 2 Al 4 Si 5 O 18, is a graph showing changes in linear thermal expansion coefficient x. In the composition formula 0.60 glass _{+ (0.40-x) TiO 2} + xMg 2 Al 4 Si 5 O 18, is a graph showing changes in the dielectric constant by x. In the composition formula 0.78 glass _{+ (0.22-x) TiO 2} + xMg 2 Al 4 Si 5 O 18, is a graph showing changes in linear thermal expansion coefficient x. In the composition formula 0.78 glass _{+ (0.22-x) TiO 2} + xMg 2 Al 4 Si 5 O 18, is a graph showing changes in the dielectric constant by x. It is a figure which shows one relationship between the laminated structure of a multilayer substrate, and the curvature of a board | substrate.

Claims (7)

A SiO ₂ 46 to 60 _{wt%, B} 2 O 3 0.5 to 5 _wt%, a composition of _Al 2 O 3 _6~17.5 wt% and an alkaline earth metal oxide 25-45 wt%, the Glass containing at least 60% by weight of SrO in the alkaline earth metal oxide contains 60 to 78 vol%, titania 14 to 27 vol%, cordierite 5 to 15.5 vol%, and 50 to linear thermal expansion coefficient at 300 ° C. is at ^{5.90 × 10 -6 /℃~6.40×10 -6 / ℃} , low-temperature fired substrate, wherein the relative dielectric constant at room temperature 1.9GHz is 10 or more material. In the multilayer wiring board in which the glass-ceramic mixed layers are laminated, at least one of the glass-ceramic mixed layers is composed of 46 to 60% by weight of SiO ₂ , 0.5 to 5% by weight of B ₂ O ₃ , Al ₂ O ₃ 6-17.5 wt% and has a composition of an alkaline earth metal oxide 25-45 wt%, glass 60～78Vol% at least 60% by weight of the alkaline earth metal oxide is SrO The titania contains 14 to 27 vol%, the cordierite contains 5 to 15.5 vol%, and the linear thermal expansion coefficient at 50 to 300 ° C is 5.90 × 10 ^-6 / ° C to 6.40 ×. A multilayer wiring board comprising a low-temperature fired substrate material having a relative dielectric constant of 10 or more at 10 ⁻⁶ / ° C. and a room temperature of 1.9 GHz. The difference in linear thermal expansion coefficient at 50 to 300 ° C. between the glass-ceramic mixed layer made of the low-temperature fired substrate material and another glass-ceramic mixed layer other than the glass-ceramic mixed layer is 0.25 × 10 ^−6. The multilayer wiring board according to claim 2, wherein the temperature is not higher than / ° C.   4. The multilayer wiring board according to claim 2, wherein the other glass-ceramic mixed layer has a relative dielectric constant of 5 to 8 at a room temperature of 1.9 GHz. The other glass - ceramic mixed _layer, SiO 2 46 to 60 _{wt%, B} 2 O 3 _{0.5~5 wt%, Al} 2 O 3 _6~17.5 wt% and alkaline earth metal oxides 25 Glass comprising a low-temperature fired substrate material having a composition of 45% by weight, 58 to 76% by volume of glass in which at least 60% by weight of the alkaline earth metal oxide is SrO, and 24 to 42% by volume of alumina. The multilayer wiring board according to claim 2, wherein the multilayer wiring board is a ceramic mixed layer.   6. The multilayer wiring board according to claim 2, wherein the warpage of the multilayer wiring board is 200 μm or less per 50 mm square. 7. The multilayer wiring board according to claim 2, wherein the warpage of the multilayer wiring board is 200 [mu] m or less per 100 mm square.

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