Glass substrate for reinforcing wiring substrate

Abstract

Provided is a glass substrate for reinforcing a wiring board, which has excellent low dielectric loss characteristics. A glass substrate for reinforcing a wiring board, the glass substrate comprising a sheet glass having a glass composition in which the content of SiO2 + Al2O3 + B2O3 is 87% or more in mol% and a thickness t of 5-500 [mu] m (inclusive).

Description

Technical Field

[0001] The present invention relates to a glass substrate used for a prepreg and a core material for a wiring substrate. Background Art

[0002] In recent years, wiring substrates such as printed wiring substrates with low dielectric loss are required as next-generation communication components. In the past, prepregs and core materials used for printed wiring substrates used base materials impregnated with resin in cloth woven from glass fibers, i.e., glass cloth. So far, E-glass fabrics are generally used, but especially in high-frequency applications, there is a disadvantage of high dielectric loss. Therefore, in patent document 1, a fabric using quartz glass fibers with less dielectric loss is used. If high frequency is reached, the skin effect in which current flows easily near the surface of the wiring tends to become significant, and if the surface of the substrate is large, it takes time for the signal to be transmitted, so the transmission loss tends to become larger.

[0003] In a substrate in which resin is impregnated in glass cloth, there is a tendency for the ratio of glass / resin to be different locally. If the ratio is different, the transmission loss will also be different, which may become a factor in changes in the signal waveform and signal propagation delay. It is also important to improve the performance and lightness of the substrate, and for this purpose, it is effective to reduce the thickness of the prepreg and the core material. Therefore, it is proposed to use glass cloth with small diameter fibers. However, the small diameter of the fiber reduces the rigidity of the prepreg and the core material, and there is a tendency for the glass / resin interface to increase. If there are gaps or foreign matter at the interface between dissimilar materials, there is a possibility of causing circuit disconnection, etc., so it is preferred that the area of ​​the glass / resin interface is as small as possible. Therefore, in Patent Document 2, it is proposed to use plate glass with limited surface roughness instead of fabric.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 6999487

[0007] Patent Document 2: Japanese Patent Application Publication No. 2011-225777 Summary of the invention

[0008] Problems to be solved by the invention

[0009] When plate glass is used as a prepreg or core material for a printed wiring board, there is a problem that the dielectric loss of the plate glass is large and the desired low dielectric properties cannot be obtained. This tendency is particularly prominent when the plate glass is made thinner.

[0010] In view of the above, an object of the present invention is to provide a glass substrate for reinforcing a wiring board having excellent low dielectric loss characteristics.

[0011] Means of solving the problem

[0012] The present inventors have repeatedly conducted various experiments and, as a result, have found that the above-mentioned technical problems can be solved by using a glass substrate having a predetermined glass composition, and proposed the present invention.

[0013] (1) That is, the glass substrate for reinforcing a wiring board of the present invention is characterized in that it comprises a plate glass having a glass composition in which the content of SiO2+Al2O3+B2O3 is 87% or more in mol % and a thickness t of 5 μm or more and 500 μm or less. In addition, "SiO2+Al2O3+B2O3" means the total amount of SiO2, Al2O3 and B2O3.

[0014] (2) In the wiring board reinforcement glass substrate of the present invention, in the above (1), the fictive temperature of the glass is preferably equal to or lower than the glass transition temperature Tg+300°C.

[0015] As the wiring substrate of the next generation communication component, high density installation is implemented in stacking to increase capacity. Therefore, the glass substrate as a reinforcing material has a tendency to require thinning. If the glass substrate is thinned, the cooling rate is accelerated and the fictive temperature is easily raised, and as a result, there is a tendency that the dielectric loss becomes larger. The inventors etc. focus on this point, and find that by controlling the fictive temperature of the glass substrate as low as possible as mentioned above, low dielectric loss characteristics can be achieved.

[0016] (3) In the wiring board reinforcement glass substrate of the present invention, in the above (1) or (2), it is preferred that a plate width L of the plate glass is 5 mm or more and 1000 mm or less.

[0017] (4) It is preferred that the glass substrate for reinforcing a wiring substrate of the present invention, in any one of the above (1) to (3), the value of the ratio t / L of the thickness t of the plate glass to the plate width L is 0.01×10 －3 Above and 20×10 －3 the following.

[0018] (5) In the wiring board reinforcement glass substrate of the present invention, in any one of (1) to (4) above, the plate glass preferably has a dielectric loss of 0.027 or less at 25° C. and a frequency of 40 GHz.

[0019] (6) The glass substrate for reinforcing a wiring board of the present invention is preferably used as a prepreg or a core material for a wiring board in any one of (1) to (5) above.

[0020] (7) The prepreg of the present invention comprises the plate glass according to any one of (1) to (6) above, and a resin layer provided on at least one main surface of the plate glass.

[0021] Effects of the Invention

[0022] According to the present invention, a glass substrate for reinforcing a wiring board having excellent low dielectric loss characteristics can be provided. DETAILED DESCRIPTION

[0023] Hereinafter, the glass substrate for reinforcing a wiring board (hereinafter, also simply referred to as a “glass substrate”) of the present invention will be described in detail.

[0024] The glass substrate of the present invention includes a plate glass having a predetermined fictive temperature. The so-called fictive temperature of glass refers to the temperature at which the glass structure is frozen, and varies according to the melting temperature, cooling rate, annealing temperature and time. If the fictive temperature is high, the structure becomes sparse and the dielectric loss tends to increase. Therefore, the fictive temperature of the plate glass is preferably below the glass transition temperature Tg+300°C, below Tg+290°C, below Tg+250°C, below Tg+230°C, below Tg+200°C, below Tg+180°C, below Tg+160°C, below Tg+150°C, below Tg+130°C, below Tg+100°C, below Tg+80°C, below Tg+50°C, and particularly preferably below Tg+30°C. On the other hand, in order to lower the fictive temperature, it is necessary to lower the melting temperature, or lower the cooling rate, and then extend the annealing time, which tends to reduce productivity. Therefore, the appropriate fictive temperature is preferably Tg-200°C, Tg-150°C, Tg-100°C or higher, and particularly preferably Tg-75°C or higher.

[0025] The fictive temperature of plate glass can be measured by the following method. First, the density of the plate glass is measured by the Archimedes method (density 1). Thereafter, the plate glass is heat treated for 1 hour near the glass transition temperature Tg + 300°C, and after water cooling, the density is measured by the Archimedes method (density 2). This measurement is repeated at multiple heat treatment temperatures. In particular, it is preferred to set the heat treatment temperature in such a way that density 2 can obtain values ​​higher than density 1 and values ​​lower than density 1. Thus, a graph showing the correlation between density and heat treatment temperature can be obtained. In the obtained graph, the temperature corresponding to density 1 is the fictive temperature. When the sample is small in size, the density can also be measured by the heavy liquid method. If a resin or metal wiring is formed on the plate glass, the wiring is removed using a ferric chloride liquid solution, and the resin layer can be removed by heat treatment at 300°C to 500°C for several hours. Thereafter, the fictive temperature of the plate glass can be measured by the above method.

[0026] The viscosity of the plate glass at the fictive temperature is preferably 10 9.0 dPa·s or more, 10 9.3 dPa·s or more, 10 9.5 dPa·s or more, 10 10.0dPa·s or more, particularly preferably 10 10.5 On the other hand, in order to increase the viscosity at the fictive temperature, it is necessary to lower the melting temperature, reduce the cooling rate, or extend the annealing time, which tends to reduce productivity. Therefore, the upper limit of the viscosity at the fictive temperature of the plate glass is preferably 10 14.0 dPa·s or less, 10 13.5 dPa·s or less, particularly preferably 10 13.0 dPa·s or less.

[0027] If the thickness t of the plate glass is too thin, when the glass substrate of the present invention is used to manufacture prepregs, it is difficult to handle and easy to break. In addition, if the wall thickness of the plate glass is too thin, the cooling rate of the glass is accelerated, and there is a tendency for the fictive temperature to become higher, so the result is that the dielectric loss is easily increased. On the other hand, if the thickness t of the plate glass is too thick, for example, when the glass substrate of the present invention is used for prepreg, the glass content in the prepreg becomes higher, so the dielectric loss of the prepreg as a whole is likely to become larger. Therefore, the lower limit of the thickness t of the plate glass is preferably more than 5 μm, more than 8 μm, more than 10 μm, more than 15 μm, more than 18 μm, more than 20 μm, more than 25 μm, more than 30 μm, more than 35 μm, more than 40 μm, more than 45 μm, and particularly preferably more than 50 μm. On the other hand, the upper limit of the thickness t of the plate glass is preferably 500 μm or less, 450 μm or less, 400 μm or less, 350 μm or less, 300 μm or less, 250 μm or less, 200 μm or less, particularly preferably 150 μm or less.

[0028] If the plate width L of the plate glass is too narrow, the installation process of the wiring substrate is difficult. In addition, there is a tendency for the cooling rate of the glass to accelerate, or the imaginary temperature to rise, and as a result, the dielectric loss is easily increased. On the other hand, if the plate width L of the plate glass is too wide, it is difficult to obtain a smooth plate due to uneven thickness or warping. Therefore, the lower limit of the plate width L is preferably more than 5mm, more than 10mm, more than 15mm, more than 20mm, more than 25mm, more than 30mm, more than 35mm, more than 40mm, more than 45mm, and particularly preferably more than 50mm. On the other hand, the upper limit of the plate width L is preferably less than 1000mm, less than 900mm, less than 800mm, less than 700mm, less than 600mm, less than 500mm, less than 400mm, less than 350mm, and particularly preferably less than 300mm.

[0029] If the value of the ratio t / L of the thickness t of the plate glass to the plate width L is too small, the cooling rate of the glass tends to be accelerated or the fictive temperature tends to be increased, so the dielectric loss tends to be increased. On the other hand, if the value of t / L is too large, for example, when the glass substrate of the present invention is used for a prepreg, the glass content in the prepreg becomes high, so the dielectric loss of the prepreg as a whole may increase. Therefore, the lower limit of the value of t / L is preferably 0.01×10 －3 Above, 0.02×10 －3 Above, 0.03×10 －3 More than 0.04×10 －3 On the other hand, the upper limit of the value of t / L is preferably 40×10 －3 Below, 35×10 －3 Below, 30×10 －3 Below, 25×10 －3 Below, particularly preferably 20×10 －3 the following.

[0030] In the glass substrate for strengthening the wiring substrate of the present invention, the glass composition of the plate glass is preferably 87% or more, 87.5% or more, and particularly preferably 88% or more in terms of molar % SiO2+Al2O3+B2O3. If the content of SiO2+Al2O3+B2O3 is too little, the oxides forming the network in the glass will decrease, and the non-bridging oxygen will increase. As a result, as the fictive temperature increases, the glass structure tends to become chaotic, and there is a tendency for the dielectric constant and the dielectric loss tangent to increase. On the other hand, the upper limit of the content of SiO2+Al2O3+B2O3 is not particularly limited, and is less than 100%, but if it is too much, the viscosity of the glass becomes high and the productivity may decrease. Therefore, the upper limit of the content of SiO2+Al2O3+B2O3 can be less than 99%, less than 98%, less than 97%, less than 96.8%, less than 96.5%, and in particular, less than 96%.

[0031] SiO2 is the composition of the skeleton that forms a network structure in glass, and is also the composition that reduces dielectric constant and dielectric loss tangent in addition. If SiO2 content is too little, then it is difficult to obtain the described effect. On the other hand, if SiO2 content is too much, then the fusibility of raw material reduces, and it is difficult to obtain homogeneous glass. There is the tendency that the forming temperature rises in addition, and productivity reduces. Therefore, SiO2 suitable lower limit range is more than 57%, more than 58%, more than 59%, more than 60%, more than 64%, and suitable upper limit range is below 80%, lower than 80%, below 79%, most preferably below 78%.

[0032] Al2O3 is the skeleton that forms glass, and is the composition that suppresses the phase separation of glass and makes it stable.But if Al2O3 content is too much, then dielectric constant and dielectric loss tangent are easy to raise.Therefore, suitable upper limit range is below 20%, below 19%, below 18%, below 17%, below 16%, below 15%, below 13%, below 12%, below 11%, below 10%, below 9%, below 8%, below 7%, below 6%, especially below 5%.Al2O3 lower limit range is not particularly limited, is more than 0%, but in order to obtain the above-mentioned effect, is preferably more than 0.01%, especially preferably more than 0.015%.

[0033] B2O3 and SiO2 are the same, are the components of the skeleton that form glass, are the components that dielectric constant and dielectric loss tangent are reduced in addition.If B2O3 content is too little, then be difficult to obtain described effect.On the other hand, if B2O3 content is too much, then glass is easy to phase-splitting, and productivity may reduce.Therefore, B2O3 suitable lower limit range is more than 10%, more than 11%, more than 12%, more than 13%, more than 15%, particularly more than 16%, and suitable upper limit range is below 30%, below 28%, particularly below 27%.

[0034] As glass components constituting plate glass, the following components may be contained in addition to SiO2, Al2O3 and B2O3.

[0035] MgO is a component that reduces the viscosity of glass. Compared with alkali metal components such as Li2O, Na2O, K2O, it is a component that is difficult to increase the dielectric constant and dielectric loss tangent. In addition, by making MgO coexist with alkali metal elements, it has the effect of suppressing the dielectric loss caused by the movement of alkali metal ions. However, if the content of MgO is too much, it may promote phase separation. This tendency is significant in the glass composition system with less Al2O3 content. Therefore, the appropriate upper limit range of MgO content is less than 15%, less than 13%, less than 10%, less than 9%, less than 8%, and particularly less than 7%. In addition, the lower limit range of MgO is not particularly limited, and is more than 0%, but in order to obtain the above-mentioned effect, it is preferably more than 0.01%, more than 0.05%, more than 0.07%, and particularly preferably more than 0.1%.

[0036] CaO is the same as MgO, and is a component that reduces the viscosity of glass. Compared with the alkali metal components of Li2O, Na2O, K2O, etc., it is a component that is difficult to increase the dielectric constant and dielectric loss tangent. In addition, by making CaO coexist with alkali metal elements, there is an effect of suppressing the movement of alkali metal ions. However, if the content of CaO is too much, it may promote phase separation. This tendency is significant in the glass composition system with little Al2O3 content. Therefore, the suitable upper limit range of CaO content is less than 15%, less than 13%, less than 10%, less than 9%, and particularly less than 8%. In addition, the lower limit range of CaO is not particularly limited, and is more than 0%, but in order to obtain the above-mentioned effect, it is preferably more than 0.01%, more than 0.05%, more than 0.07%, and particularly preferably more than 0.1%.

[0037] SrO is the same as MgO and CaO, and is a component that reduces the viscosity of glass. Compared with the alkali metal components of Li2O, Na2O, K2O, etc., it is a component that is difficult to increase the dielectric constant and dielectric loss tangent. In addition, SrO has the effect of suppressing the movement of alkali metal ions by coexisting with alkali metal elements. However, if the content of SrO is too much, it is possible to promote phase separation. This tendency is particularly significant in the glass composition system with less Al2O3 content. Therefore, the suitable upper limit range of SrO content is less than 5%, less than 4%, less than 3%, less than 2%, less than 1.5%, less than 1%, less than 0.8%, less than 0.7%, less than 0.6%, less than 0.5%, less than 0.4%, less than 0.3%, less than 0.2%, less than 0.1%, especially less than 0.1%. The lower limit of SrO is not particularly limited but is 0% or more. However, in order to obtain the above-mentioned effect, it is preferably 0.01% or more, 0.05% or more, and particularly preferably 0.07% or more.

[0038] BaO, like MgO and CaO, is a component that reduces the viscosity of glass, and is a component that is difficult to increase dielectric constant and dielectric loss tangent compared to the alkali metal components of Li2O, Na2O, K2O, etc. In addition, BaO has the effect of suppressing the movement of alkali metal ions by coexisting with alkali metal elements. However, if the content of BaO is too much, it is possible to promote phase separation. This tendency is particularly significant in the glass composition system with less Al2O3 content. Therefore, the suitable upper limit range of BaO content is less than 5%, less than 4%, less than 3%, less than 2%, less than 1.5%, particularly less than 1%, and further less than 0.1%. In addition, the lower limit range of BaO is not particularly limited, and is more than 0%, but in order to obtain the above-mentioned effect, it is preferably more than 0.01%, more than 0.05%, more than 0.07%, and particularly preferably more than 0.1%.

[0039] ZnO, like MgO and CaO, is a component that reduces the viscosity of glass, and is a component that is difficult to increase dielectric constant and dielectric loss tangent compared to the alkali metal components of Li2O, Na2O, K2O, etc. In addition, ZnO has the effect of suppressing the movement of alkali metal ions by coexisting with alkali metal elements. However, if the content of ZnO is too much, it is possible to promote phase separation. This tendency is particularly significant in the glass composition system with less Al2O3 content. Therefore, the suitable upper limit range of ZnO content is less than 5%, less than 4%, less than 3%, less than 2%, less than 1.5%, and particularly less than 1%. In addition, the lower limit range of ZnO is not particularly limited, and is more than 0%, but in order to obtain the above-mentioned effect, it is preferably more than 0.01%, more than 0.05%, more than 0.07%, and particularly preferably more than 0.1%.

[0040] Li2O is a component that reduces the viscosity of glass, and is a component that makes glass easy to manufacture and can reduce manufacturing costs, but if its content is too much, dielectric constant and dielectric loss tangent are easily increased. In addition, when the glass substrate of the present invention is used as a wiring substrate, if the wiring substrate is exposed to a high temperature and high humidity environment, the Li2O component is likely to dissolve from the glass, and if the Li2O component is precipitated at the wiring position in the wiring substrate, it may hinder electrical signals. Therefore, the suitable upper limit range is less than 3%, less than 2.5%, less than 2.3%, less than 2.1%, less than 2.0%, less than 1.5%, less than 1.4%, particularly less than 1.3%. On the other hand, the lower limit range of Li2O is not particularly limited, and is more than 0%, but in order to obtain the above-mentioned effect, it is preferably more than 0.001%, more than 0.005%, more than 0.01%, more than 0.02%, and particularly preferably more than 0.05%.

[0041] Na2O is the same as Li2O, and is a component that reduces the viscosity of glass. It is a component that makes glass easy to manufacture and can reduce manufacturing costs, but if its content is too much, dielectric constant and dielectric loss tangent are easily increased. In addition, when the glass substrate of the present invention is used as a wiring substrate, if the wiring substrate is exposed to a high temperature and high humidity environment, the Na2O component is likely to dissolve from the glass, and if the Na2O component is precipitated at the wiring position in the wiring substrate, it may hinder electrical signals. Therefore, the suitable upper limit range is less than 3%, less than 2.4%, particularly less than 2.3%. On the other hand, the lower limit range of Na2O is not particularly limited, and is more than 0%, but in order to obtain the above-mentioned effect, it is preferably more than 0.01%, more than 0.05%, more than 0.08%, more than 0.1%, more than 0.5%, more than 0.8%, and particularly preferably more than 1%.

[0042] K2O, like Li2O and Na2O, is a component that reduces the viscosity of glass and is a component that makes glass easy to manufacture and can reduce manufacturing costs, but if its content is too much, the dielectric constant and dielectric loss tangent are easily increased. In addition, when the glass substrate of the present invention is used as a wiring substrate, if the wiring substrate is exposed to a high temperature and high humidity environment, the K2O component is likely to dissolve from the glass, and if the K2O component is precipitated at the wiring position in the wiring substrate, it may hinder the electrical signal. Therefore, the suitable upper limit range is less than 3%, less than 2.4%, and particularly less than 2.3%. On the other hand, the lower limit range of K2O is not particularly limited, and is more than 0%, but in order to achieve the above-mentioned effect, it is preferably more than 0.01%, more than 0.05%, more than 0.08%, and particularly preferably more than 0.1%.

[0043] If Li2O + Na2O + K2O (the total amount of Li2O, Na2O and K2O) is too much, the dielectric constant and dielectric loss tangent are likely to increase. In addition, when the glass substrate of the present invention is used as a wiring substrate, if the wiring substrate is exposed to a high temperature and high humidity environment, the Na2O component, the Li2O component and / or the K2O component may dissolve from the glass. If these components are precipitated at the wiring position in the wiring substrate, the electrical signal may be hindered. Therefore, the appropriate upper limit range is less than 6%, less than 5.5%, and less than 5%. On the other hand, the lower limit range of Li2O + Na2O + K2O is not particularly limited to more than 0%, but in order to achieve the above-mentioned effect, it is preferably more than 0.1%, more than 0.3%, more than 0.5%, and particularly preferably more than 1%. In addition, Li2O, Na2O and K2O are components that are easily dissolved from glass, but by allowing them to coexist, they can hinder each other's movement in the glass and inhibit dissolution. Therefore, it is preferred to contain two or three of these components in a mixed manner.

[0044] ZrO2 is a component that improves the chemical durability of glass. However, if the content of ZrO2 is too much, the liquidus temperature becomes high, or devitrification may occur during forming, which reduces production efficiency. Therefore, the appropriate upper limit range is less than 1.5%, less than 1.3%, less than 1.2%, less than 1%, less than 0.5%, less than 0.1%, less than 0.05%, and particularly less than 0.03%. On the other hand, the lower limit range of ZrO2 is not particularly limited and is more than 0%, but in order to achieve the above-mentioned effect, it is preferably more than 0.001%, more than 0.003%, and particularly preferably more than 0.005%.

[0045] Fe2O3 is a component with a clarifying effect. However, if the content of Fe2O3 is too much, dielectric constant and dielectric loss tangent may rise. Therefore, the suitable upper limit range is below 0.15%, below 0.1%, below 0.09%, particularly below 0.08%. On the other hand, the lower limit range of Fe2O3 is not particularly limited, being more than 0%, but in order to obtain the above-mentioned effect, preferably more than 0.0001%, more than 0.0005%, more than 0.001%, more than 0.005%, more than 0.006%, more than 0.007%, more than 0.008%, more than 0.009%, more than 0.010%, more than 0.011%, more than 0.012%, particularly preferably more than 0.013%.

[0046] SnO2 is also a component with a clarifying effect. Specifically, since the valence of Sn changes according to the temperature of the molten glass, oxygen is released above 1500°C. However, if its content is high, the light absorption in the visible range becomes large, and the glass may be colored. Therefore, the appropriate upper limit range is below 0.5%, below 0.45%, below 0.4%, below 0.35%, and especially below 0.3%. On the other hand, the lower limit range of the content of SnO2 is not particularly limited, and is above 0%, but in order to achieve the above-mentioned effect, it is preferably above 0.01%, above 0.02%, and particularly preferably above 0.05%. In addition, when the content of alkali metal components such as Li2O, Na2O and K2O is small, the melting temperature is easy to increase. SO3, which also has a clarifying effect, decomposes above 1400°C and releases SO2 gas, but if the gas is released in a state where the viscosity of the molten glass is high, sufficient defoaming cannot be expected. In this case, SnO2 is preferably used as a clarifying agent.

[0047] F is also a component with a clarifying effect. In addition, it also has the effect of reducing the viscosity of molten glass. However, if its content is high, the environmental burden increases, or the melting equipment may be corroded. Therefore, the appropriate upper limit range is below 0.5%, below 0.3%, below 0.2%, and particularly below 0.1%. On the other hand, the lower limit range of the content of F is not particularly limited, and is above 0%, but in order to obtain the above-mentioned effect, it is preferably above 0.01%, above 0.02%, and particularly preferably above 0.05%.

[0048] Cl is also a component with a clarifying effect. In addition, it also has the effect of reducing the viscosity of molten glass. However, if its content is high, the environmental burden increases, or the melting equipment may be corroded. Therefore, the appropriate upper limit range is below 0.5%, below 0.3%, below 0.2%, and particularly below 0.1%. On the other hand, the lower limit range of the Cl content is not particularly limited, and is above 0%, but in order to obtain the above-mentioned effect, it is preferably above 0.01%, above 0.02%, and particularly preferably above 0.05%.

[0049] In addition, if the composition with a large content of B2O3 is melted by combustion heating, the evaporation amount of B2O3 from the glass melt becomes more. Therefore, it is also possible to use electric heating. As an electrode for electric current, for example, MoO3 can be used, but MoO3 has the possibility of melting in the glass melt. If MoO3 coexists with polyvalent oxides such as Fe2O3 or SnO2, redox reaction occurs between the polyvalent oxides, and the glass may be colored. Therefore, the suitable upper limit range of MoO3 in the glass is below 1000ppm, below 900ppm, below 700ppm, below 500ppm, below 300ppm, and particularly below 200ppm. On the other hand, the lower limit range of the content of MoO3 is not particularly limited, and is above 0ppm, but can also be above 0.01ppm, above 0.02ppm, and particularly can be contained in the range above 0.03ppm.

[0050] In addition to the above-mentioned components, TiO2 may be contained in an amount of less than 5%, less than 1%, and particularly less than 0.2%.

[0051] Because the dielectric loss tangent is easily affected by charge shift, the electronegativity difference between the constituent elements of each component (constituent elements other than oxygen atoms) and oxygen atoms is easily affected. Specifically, if there are many network-forming oxides such as SiO2, Al2O3, and B2O3, the glass structure is difficult to deform relative to the change of the electric field, and the dielectric loss tangent tends to become smaller. On the other hand, if there are many modified oxides such as Li2O, Na2O, K2O, MgO, CaO, SrO, and BaO, the glass structure and localized charge shift are easy to change relative to the change of the electric field, so the dielectric loss tangent tends to become larger. In addition, if there are many modified oxides, the glass structure becomes weak, so especially when the fictive temperature is high, the glass structure will be frozen in a disordered state, so the dielectric loss tangent tends to become larger. In view of the above, the ratio of the electronegativity of the network-forming oxide to the electronegativity of the modifying oxide, i.e., the value of NWF / NWM is preferably 5 or more, 7 or more, 8 or more, 9 or more, 10 or more, 12 or more, 12.5 or more, 13 or more, 13.5 or more, 14 or more, 14.5 or more, 14.8 or more, 14.9 or more, and particularly preferably 15 or more. On the other hand, if the value of NWF / NWM becomes higher, the melting temperature increases, so the productivity decreases. Therefore, the upper limit of NWF / NWM is preferably 160 or less, 155 or less, 150 or less, 145 or less, 100 or less, 50 or less, 40 or less, 30 or less, and particularly preferably 20 or less.

[0052] The values ​​of NWF and NWM can be calculated by the following formula using the content (mol %) of each component and the electronegativity difference between each element and the oxygen atom. The electronegativity was calculated using the values ​​of Pauling's electronegativity shown in Table 1.

[0053] NWF = Σ (content of network-forming oxide × coefficient of constituent element of network-forming oxide × electronegativity difference between constituent element of network-forming oxide and oxygen atom ΔX)

[0054] NWM = Σ (content of modified oxide × coefficient of constituent element of modified oxide × electronegativity difference between constituent element of modified oxide and oxygen atom ΔX)

[0055]

Table 1

[0056]

[0057] (Characteristics of glass substrate)

[0058] The glass substrate for reinforcing the wiring substrate of the present invention preferably has a dielectric constant of less than 5 at a frequency of 25°C and 40GHz, and preferably has a dielectric loss tangent of less than 0.005. If the dielectric constant and the dielectric loss tangent are too high, the dielectric loss becomes large, which may cause attenuation of the radio waveform. This tendency is particularly significant in the case of high-frequency applications. Therefore, the upper limit range of the appropriate dielectric constant is less than 5, less than 4.9, less than 4.8, less than 4.6, less than 4.5, less than 4.4, less than 4.3, and less than 4.2. The lower the dielectric constant, the more preferred, but in the case of glass, the lower limit is actually about 3. In addition, the upper limit range of the appropriate dielectric loss tangent is less than 0.005, less than 0.0045, and less than 0.004. The dielectric loss tangent is also preferably low, but in the case of glass, the lower limit is actually about 0.001. In addition, the upper limit of the dielectric loss, which is the product of the dielectric constant and the dielectric loss tangent, is preferably 0.025 or less, 0.024 or less, 0.023 or less, 0.022 or less, 0.021 or less, or 0.020 or less. Although the dielectric loss is preferably lower, in the case of glass, the lower limit is actually about 0.003.

[0059] (Method for manufacturing glass substrate)

[0060] First, glass raw materials are prepared according to the desired composition and melted in a melting furnace or a melting pot. As glass raw materials, natural raw materials, chemical raw materials, or cullet can be used. By using water-containing raw materials such as hydroxides, the amount of water in the glass can also be adjusted. As heating methods, hydrogen combustion, oxygen combustion, and electric heating can be listed. Two or more of these methods can also be combined.

[0061] Molten glass is formed and cut as needed to obtain a glass substrate. The forming method includes flattening, overflow forming, slit down-drawing, redrawing, float forming, etc. The formed glass may be thinned by chemical grinding, mechanical grinding, etching, etc.

[0062] (Prepreg)

[0063] The prepreg of the present invention comprises the plate glass and a resin layer provided on at least one main surface thereof. Here, in order to improve the adhesion between the plate glass and the resin layer, a silane coupling agent layer is preferably provided between the plate glass and the resin layer. Specifically, a silane coupling agent is preferably applied to the surface of the plate glass, and a resin layer is provided on the obtained silane coupling agent layer.

[0064] The silane coupling agent can be applied by spin coating, dip coating, spray coating, or atomization coating. Alternatively, the silane coupling agent may be applied immediately after the plate glass is manufactured, and the silane coupling agent may be solidified while annealing in an annealer. Alternatively, the silane coupling agent may be applied while the molten glass is formed into plate glass.

[0065] Examples of the silane coupling agent include γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-(2-aminoethyl)aminopropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane hydrochloride, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, and vinyltriethoxysilane. It is preferred to select these agents appropriately according to the type of the resin layer to be formed.

[0066] As the resin used for the resin layer, a thermosetting resin can be cited. Specific examples of the thermosetting resin include novolac-type phenolic resins such as phenol novolac resin, cresol novolac resin, and bisphenol A novolac resin, unmodified Resol phenolic resin, Resol phenolic resin modified with tung oil, linseed oil, walnut oil, and the like, and the like; bisphenol-type epoxy resins such as bisphenol A-type epoxy resin, bisphenol F-type epoxy resin, bisphenol S-type epoxy resin, bisphenol E-type epoxy resin, bisphenol M-type epoxy resin, bisphenol P-type epoxy resin, and bisphenol Z-type epoxy resin, novolac-type epoxy resins such as phenol novolac resin, cresol novolac epoxy resin, and the like; biphenyl-type epoxy resins, biphenyl aralkyl-type epoxy resins, and arylalkylene-type epoxy resins. Epoxy resins such as alkylene epoxy resins, naphthalene epoxy resins, anthracene epoxy resins, phenoxy epoxy resins, dicyclopentadiene epoxy resins, norbornene epoxy resins, adamantane epoxy resins, and fluorene epoxy resins; urea-formaldehyde (urea) resins; resins having triazine rings such as melamine resins; unsaturated polyester resins, bismaleimide resins (BT resins), polyurethane resins, diallylphthalate resins, silicone resins, resins having benzoxazine rings, cyanate resins, etc. One of them may be used alone, or two or more thereof may be used in combination. In the case of using one resin, two or more thereof having different weight average molecular weights may be used in combination. Its prepolymer may also be used in combination with the above-mentioned resins.

[0067] Example

[0068] Hereinafter, the present invention will be described based on examples, but the present invention is not limited to these examples.

[0069] Tables 2 to 5 show Examples 1 to 16 of the present invention and Comparative Example 1.

[0070]

Table 2

[0071]

[0072]

Table 3

[0073]

[0074]

Table 4

[0075]

[0076]

Table 5

[0077]

[0078] Each sample described in Tables 2 to 5 was prepared as follows.

[0079] First, weigh a total of 500g of various glass raw materials such as natural raw materials and chemical raw materials, melt them and make the glass composition shown in Tables 1 and 2 to prepare the raw material batch. The obtained raw material batch is crushed and mixed for 20 minutes, and then put into a 300cc platinum-rhodium crucible. Then, it is heated at about 1450-1680°C for 6 hours in an indirect heating electric furnace in an atmosphere to form molten glass. The obtained molten glass is poured onto a carbon plate, rolled with a metal roller to a thickness of 5mm and cooled to room temperature to obtain a glass sample. After keeping the obtained sample in an annealer set to each imaginary temperature described in the table for 1 hour, the sample is quickly taken out of the annealer and immersed in water (20°C) for rapid cooling. Thus, a sample (plate glass) is obtained.

[0080] The following properties were measured for each of the obtained samples.

[0081] The strain point, annealing point and softening point were measured by the fiber elongation method.

[0082] The glass transition temperature Tg is measured using a dilatometer. If the sample amount is small, it can also be measured using a DTA (differential thermal analyzer).

[0083] High temperature viscosity 10 4 Temperature at dPa·s, high temperature viscosity 10 3 dPa·s, and high temperature viscosity 10 2.5 The temperature under dPa·s (expressed as "10^4", "10^3" and "10^2.5" in the table) is measured by crushing a part of the glass sample obtained by the above method to an appropriate size in advance, putting it into a platinum crucible, heating it to a molten state, and then measuring it by the platinum ball pulling method.

[0084] The viscosity at the fictive temperature is calculated based on the strain point, annealing point, softening point, high temperature viscosity 10 4 Temperature at dPa·s, high temperature viscosity 10 3 Temperature and high temperature viscosity at dPa·s10 2.5 The viscosity curve is created by comparing the temperature at dPa·s and the viscosity corresponding to the fictive temperature is calculated from the viscosity curve.

[0085] The dielectric constant ε and dielectric loss tangent tanδ at a frequency of 40 GHz are measured as follows. The glass sample obtained by the above method is processed into a size of 30 mm × 40 mm × 0.15 mmt. The two main surfaces are mirror-finished by polishing. After the obtained sample is kept in an annealer set to the imaginary temperature described in the table for 1 hour. The sample is quickly removed from the annealer and immersed in water (20°C) for rapid cooling. The measurement is performed using a resonator and a vector analyzer for 40 GHz by the split cylindrical resonator method. In addition, the measurement is performed at room temperature (25°C).

[0086] Young's modulus was measured using a glass sample obtained by the above method and processed into a 40×20×2mm sample piece. In addition, both surfaces of the glass sample piece with a thickness of 2mm were polished with a polishing liquid containing 1200 aluminum oxide powder dissolved in water. Gold (1500Å or more) was vapor-deposited on the sample, and the width, length, thickness, and weight of the sample were measured. The measurement was performed using a free resonance elastic modulus measuring device JE-RT3 manufactured by Japan Techno-Plus (company).

[0087] As shown in the table, the content of SiO2+Al2O3+B2O3 in Examples 1 to 16 is 93.7 mol% or more, and the dielectric loss is as low as 0.0182 or less. On the other hand, the content of SiO2+Al2O3+B2O3 in Comparative Example 1 is as low as 5.7 mol%, so the dielectric loss is as high as 0.0283.

[0088] Industrial Applicability

[0089] The glass substrate of the present invention is suitable for reinforcing wiring substrates such as printed wiring substrates, multilayer wiring substrates, and substrates for high-density semiconductor packaging used in a high-frequency band of 10 GHz or higher.

Claims

1. A glass substrate for reinforcing a wiring substrate, comprising a plate glass having a glass composition of SiO2+Al2O3+B2O3 of 87% or more in mol % and a thickness t of 5 μm or more and 500 μm or less.

2. The glass substrate for reinforcing a wiring substrate according to claim 1, wherein: The fictive temperature of the plate glass is equal to or lower than the glass transition temperature Tg+300°C.

3. The glass substrate for reinforcing a wiring substrate according to claim 1 or 2, wherein: The plate width L of the plate glass is 5 mm or more and 1000 mm or less.

4. The glass substrate for reinforcing a wiring substrate according to claim 1 or 2, wherein: The value of the ratio t / L of the thickness t of the plate glass to the plate width L is 0.01×10 －3 Above and 20×10 －3 the following.

5. The glass substrate for reinforcing a wiring substrate according to claim 1 or 2, wherein: The plate glass has a dielectric loss of 0.025 or less at 25° C. and a frequency of 40 GHz.

6. The glass substrate for reinforcing a wiring substrate according to claim 1 or 2, wherein: Used as prepreg or core material for wiring boards.

7. A prepreg having: The plate glass according to claim 1 or 2; and A resin layer provided on at least one main surface of the plate glass.

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