Glass material with low dielectric constant attributable to high weight percentage of boron trioxide

Abstract

A glass material with a low dielectric constant attributable to a high weight percentage of boron trioxide includes at least one component for forming the main constructure of the glass material, a fluxing component, a reinforcing component, and a modifier; wherein the at least one component for forming the main constructure of the glass material includes silicon dioxide (SiO.sub.2); the fluxing component includes boron trioxide (B.sub.2O.sub.3); the reinforcing component includes aluminum oxide (Al.sub.2O.sub.3); and the modifier includes calcium oxide (CaO). The glass material is characterized in that it has a boron trioxide (B.sub.2O.sub.3) content by weight of 30%-40%, which is higher than those in the prior art; a calcium oxide (CaO) content by weight of 1%-6%, which is lower than those in the prior art; and consequently a lower dielectric constant and a lower dissipation factor of the glass material than those in the prior art can be obtained.

Claims

1. A glass material with a low dielectric constant attributable to a high weight percentage of boron trioxide, comprising: at least one component for forming a main constructure of the glass material, wherein the at least one component for forming the main constructure of the glass material comprises silicon dioxide (SiO.sub.2), and the silicon dioxide (SiO.sub.2) makes up more than or equal to 45% and less than 50.4% by weight of the glass material; a fluxing component comprising boron trioxide (B.sub.2O.sub.3), wherein the boron trioxide (B.sub.2O.sub.3) makes up more than 35% and less than or equal to 40% by weight of the glass material and is used to reduce viscosity of the glass material when the glass material is melted; a reinforcing component comprising aluminum oxide (Al.sub.2O.sub.3), wherein the aluminum oxide (Al.sub.2O.sub.3) makes up 10%44% by weight of the glass material and is used to increase structural strength of the glass material; and a modifier comprising calcium oxide (CaO), wherein the calcium oxide (CaO) makes up 1%-6% by weight of the glass material and is used to increase water resistance of the glass material.

2. The glass material of claim 1, further comprising magnesium oxide (MgO), wherein the magnesium oxide (MgO) is used to lower a melting temperature of the glass material, and the magnesium oxide (MgO) and the calcium oxide (CaO) jointly make up 1%-8% by weight of the glass material.

3. The glass material of claim 1, further comprising at least one alkali metal oxide selected from the group consisting of sodium oxide (Na.sub.2O), potassium oxide (K.sub.2O), and lithium oxide (Li.sub.2O), wherein the at least one alkali metal oxide makes up 0.01%-1% by weight of the glass material.

4. The glass material of claim 2, further comprising at least one alkali metal oxide selected from the group consisting of sodium oxide (Na.sub.2O), potassium oxide (K.sub.2O), and lithium oxide (Li.sub.2O), wherein the at least one alkali metal oxide makes up 0.01%-1% by weight of the glass material.

5. The glass material of claim 3, wherein the aluminum oxide (Al.sub.2O.sub.3) makes up 11%-13% by weight of the glass material.

6. The glass material of claim 4, wherein the aluminum oxide (Al.sub.2O.sub.3) makes up 11%-13% by weight of the glass material.

7. The glass material of claim 5, wherein the calcium oxide (CaO) makes up 3.5%-6% by weight of the glass material.

8. The glass material of claim 6, wherein the calcium oxide (CaO) makes up 3.5%-6% by weight of the glass material.

9. The glass material of claim 7, wherein the at least one alkali metal oxide makes up 0.1%-0.5% by weight of the glass material.

10. The glass material of claim 8, wherein the at least one alkali metal oxide makes up 0.1%-0.5% by weight of the glass material.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) The present invention provides a glass material whose high weight percentage of boron trioxide imparts a low dielectric constant to the glass material, and which can be used to make glass fiber or other glass products. According to one embodiment of the invention, the glass material includes at least one component for forming the main constructure of the glass material, a reinforcing component, a fluxing component, and a modifier. The at least one component for forming the main constructure of the glass material includes silicon dioxide (SiO.sub.2), which is one of the skeletal oxides generally used to form glass and constitutes 45%-55% by weight of the glass material. The reinforcing component is intended to increase the structural strength of the glass material and at least includes aluminum oxide (Al.sub.2O.sub.3), which is another skeletal oxide generally used to form glass. When there is insufficient aluminum oxide (Al.sub.2O.sub.3), the glass material will have low water resistance and a high dielectric constant, but when the weight percentage of aluminum oxide (Al.sub.2O.sub.3) exceeds 18%, the filament drawing process used to turn the glass material into glass fiber will require a high temperature. In this embodiment, therefore, aluminum oxide (Al.sub.2O.sub.3) constitutes 10%-14%, preferably 11%-43%, by weight of the glass material.

(2) The fluxing component in this embodiment serves to reduce the viscosity of the glass material when the glass material is melted, and at least includes boron trioxide (B.sub.2O.sub.3), which constitutes 30%-40% by weight of the glass material. The modifier is used to increase the water resistance of the glass material and at least includes calcium oxide (CaO), which constitutes 1%-6% by weight of the glass material. It should be pointed out that in solid-state silicate- and borate-based glass, alkali metal ions and alkaline earth metal ions have a substantial effect on the dielectric constant of the glass; more specifically, the higher the contents of those ions, the higher the dielectric constant of the glass. Hence, while calcium oxide (CaO) is a glass network modifier capable of lowering the melting temperature of the glass material during a subsequent glass fiber forming process, increasing the calcium oxide (CaO) content will raise the dielectric constant of the glass material. In view of this, and to take advantage of the ability of boron trioxide (B.sub.2O.sub.3) to reduce the dielectric constant, dissipation factor, and melting temperature of glass, the present invention increases the boron trioxide (B.sub.2O.sub.3) content to 30%-40% by weight of the glass material and reduces the calcium oxide (CaO) content to 1%-6%, preferably 3.5%-6%, by weight of the glass material, as compared with those of the prior art. Therefore, the calcium oxide (CaO) content of the present invention is substantially lower than that (about 7%-10%) of the prior glass, and this allows the glass material of the invention to have a lower dielectric constant than its prior art counterparts (lower than about 4.5) and consequently the desired electrical properties.

(3) The glass material may also include magnesium oxide (MgO), which serves mainly to lower the melting temperature of the glass material and thereby facilitate the melting of the glass material and the formation of glass fiber. However, as the magnesium in magnesium oxide (MgO) is an alkaline earth metal, an exceedingly high magnesium oxide (MgO) content works against the reduction of the dielectric constant and dissipation factor of the glass material and may also lead to phase separation of the glass material. In this embodiment, therefore, the total magnesium oxide (MgO) and calcium oxide (CaO) content is set at 1%-8% by weight of the glass material. The glass material may also be added with at least one alkali metal oxide for use as a fluxing component, wherein the at least one alkali metal oxide may include sodium oxide (Na.sub.2O), potassium oxide (K.sub.2O), and/or lithium oxide (Li.sub.2O), and wherein the total content of the at least one alkali metal oxide is 0.01%-1% by weight of the glass material. As an excessively high alkali metal oxide content will increase the dielectric loss tangent, and impair the water resistance, of the glass material, the total content of the alkali metal oxide(s) is ideally 0.1%-0.5% by weight of the glass material.

(4) The glass material disclosed herein can be formed into glass fiber by heating the glass components and then subjecting the resulting molten glass to a filament drawing process. As the high boron trioxide (B.sub.2O.sub.3) content and low calcium oxide (CaO) content provide the glass material with a low dielectric constant and low dissipation factor, products (e.g., circuit boards) made of the glass material will have a lower dielectric loss during high-frequency transmission, which is a required electrical property of certain circuit boards. To demonstrate the technical superiority of the present invention to the prior art, the applicant conducted the following tests and obtained the test results shown below in Table 2. The log 3 fiber-forming temperature (“log 3 FT” or “T3”) is the temperature at which a melted glass composition has a viscosity of 1,000 poise. Three batches of materials B1 to B3 were prepared, each weighing 150 g and having a different composition from another batch. Each batch was poured into a 200 ml ceramic crucible and then heated at 1450° C. for about 6 hours, or until completely melted. The melt was allowed to cool down to room temperature gradually such that a glass block was formed. The glass block was cut with a diamond-tipped cutter into glass plate samples each having a length and width of 20 mm and a thickness of 2-3 mm. The dielectric constant and dissipation factor of each glass plate sample were then measured with a radio frequency (RF) impedance analyzer. According to the test results in Table 2, the glass material of the present invention has a dielectric constant equal to or lower than 4.5 and hence better electrical properties than the prior glass products.

(5) TABLE-US-00002 TABLE 2 Composition (wt %) B1 B2 B3 SiO.sub.2 49.1 49.9 47.6 B.sub.2O.sub.3 31.33 31.62 34.23 CaO 5.79 4.18 4.07 Al.sub.2O.sub.3 11.6 11.6 11.4 K.sub.2O 0.129 0.215 0.174 Na.sub.2O 0.353 0.349 0.418 MgO 0.136 0.121 — T3(° C.) 1302.36 1294.10 1284.65 Dielectric constant 4.5 4.4 4.3 (at 1 G Hz) Dissipation factor <0.001 0.001 <0.001 (at 1 G Hz)

(6) It is worth mentioning that, although the compositions of B1 to B3 in Table 2 do not include lithium oxide (Li.sub.2O), the same test results can be obtained with the addition of lithium oxide (Li.sub.2O), provided that the total alkali metal oxide content of each batch remains unchanged.

(7) While the invention herein disclosed has been described by means of specific embodiments, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope of the invention set forth in the claims.