JPH03215329A - Ultraviolet-ray shielding glass fiber composition for printed wiring board - Google Patents

Abstract

PURPOSE:To obtain the title composition capable of reinforcing printed wiring boards requiring the high speed processing of signals by incorporating a glass fiber composition of low dielectric constant with each specified proportion of Fe2O3 and TiO2. CONSTITUTION:The objective composition can be obtained by incorporating (A) 100 pts.wt. of a glass fiber composition of low dielectric constant with (B) 0.1-1.8 pts.wt. of Fe2O3 and (C) 0.1-2 pts.wt. of TiO2. The present composition has a dielectric constant of <=4.5 at a frequency of 1MHz at room temperature and is used for reinforcing printed wiring boards requiring the high speed processing of signals. Furthermore, this composition enables solder resist patterns to be formed through double-sided simultaneous exposure.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is used to strengthen printed wiring boards on which solder resist patterns are formed by photoprinting, especially printed wiring boards that require high-speed signal processing. The present invention relates to an ultraviolet-shielding glass fiber composition for printed wiring boards, which makes it possible to form a solder resist pattern by simultaneous exposure on both sides.

[Prior art and its problems] Typical long-fiber glasses commonly produced commercially as long-fiber glasses used to strengthen printed wiring boards include fiber glasses called E-glass and 621 glass. ing.

E glass is S102-Al2O3-CaO-MgO-
Composition of B2O3? For example, U.S. Pat. No. 2,334,
According to No. 961, the weight percentages are as follows.

SiO■ 52-56% A1■0312-16% CaO 1B-19% MgO 3-6% B2O. 9 to 11% G21 glass also has S10■-AI2O3-CaO-
B2O3, e.g. U.S. Pat. No. 2,571
, No. 074, the weight percentages are as follows.

SiO. 52 to 56% AI■0312 to 16% CaO 1B to 25% B2O38 to 13% However, printed wiring boards reinforced with the above-mentioned E glass and 621 glass are suitable for high-speed signal processing that is required in the electronic equipment field in recent years. The problem has arisen that it is not enough to deal with it. In order to process signals at high speed, it is necessary to increase the signal propagation speed of the printed wiring board circuit. Since the smaller the dielectric constant of a printed wiring board, the higher the signal propagation speed, the printed wiring board is required to have a dielectric constant of 3 or less. A printed wiring board is a composite material composed of glass fiber, resin, modifier, etc., and the dielectric constant of the wiring board is ultimately determined by the dielectric constant of these constituent materials, so glass fiber has a dielectric constant of 4. E glass and 621 glass have dielectric constants of 2.0% and Na2O0 to 3.5 or more.

Under the above circumstances, a glass fiber composition having a lower dielectric constant than E glass or 821 glass, so-called D type glass, has been developed and the demand for it has been increasing in recent years. In particular, devices that require high-speed signal processing, such as large computers, often use double-sided or more multilayer printed wiring boards with components mounted at high density.

By the way, with the development of electronic devices, the circuit patterns formed on printed wiring boards have become denser, and the solder resist patterns corresponding to those circuits have also become more complex.The photoprinting method has replaced the conventional screen printing molding method. It is becoming more and more used. In the photoprinting method, an ultraviolet curing resist is first applied to the surface of a wiring board, and a resist pattern is formed by ultraviolet exposure and etching. For wiring boards with circuits formed on both the top and bottom sides, exposure to ultraviolet rays is performed twice on each side, or both sides are exposed simultaneously. Compared to the method of repeating single-sided exposure, the double-sided simultaneous exposure method has higher production efficiency. However, since the glass cloth and resin that make up the wiring board transmit ultraviolet rays,
If both sides are exposed simultaneously, the ultraviolet rays irradiated from one side will affect the solder resist on the opposite side, resulting in a problem called back-burning where unnecessary parts are exposed.

In response to this problem, a method has been proposed in which a UV absorber is mixed into a resin. For example, Japanese Patent Application Laid-open No. 54-32763 uses a resin mixed with pigments such as phthalocyanine blue, dyes such as methyl violet, ultraviolet absorbers such as orthohydroxybenzophenone, and fillers such as calcium carbonate and clay. 1 shows a method of manufacturing a glass prepreg with shielding properties. Furthermore, JP-A-81-11380 discloses a method of imparting ultraviolet shielding properties to a wiring board by mixing titanium oxide powder with a resin, and a method of internally impregnating, surface coating, or surface impregnation of an organic ultraviolet absorbing substance into the wiring board. shows a method for imparting ultraviolet shielding properties to wiring boards. However, adding an absorbent to resin in this way may deteriorate the mechanical properties of the resin.
Further, it is difficult to mix and coat uniformly, and the ultraviolet shielding properties tend to be uneven, which is not preferable.

[Structure of the Invention] The present inventors have incorporated Fe2O3 and T10 into a low dielectric constant glass fiber composition used for reinforcing printed wiring boards, especially printed wiring boards that require high-speed signal processing. By simultaneously adding them in optimum proportions, it is possible to obtain sufficient ultraviolet shielding properties to prevent back-burning caused by simultaneous exposure on both sides during the formation of solder resist patterns by photoprinting without significantly impairing the necessary dielectric properties. I found out what I can do.

Generally, when Fe2O3 is added to glass, ultraviolet shielding properties are imparted to the glass because Fe3+ absorbs ultraviolet rays. However, if a large amount of Fe2O3 is added, the dielectric constant of the glass increases, making it impossible to use it to strengthen printed wiring boards for high-speed signal processing. Also Fe2
O,, is a part of FeO when glass is melted at high temperature.
Due to the action of Fe2+, absorption occurs not only in the ultraviolet region but also in the visible region, resulting in significant coloring of the glass. Furthermore, absorption occurs in the infrared region, making it difficult for heat rays to be transmitted.

Therefore, as a result of various researches, the present inventor found that Fe2
T10 on O3. The present inventors have discovered that the desired ultraviolet shielding properties can be imparted to glass while suppressing visible and infrared absorption without significantly impairing the necessary dielectric properties by coexisting with the above, and have proposed the present invention.

That is, the UV-shielding glass fiber composition for printed wiring boards of the present invention contains Fe2O3 in weight% relative to 100% by weight of a low dielectric constant glass fiber composition having a dielectric constant of 4.5 or less at a frequency of 1 MHz at room temperature. but? ．． 1-1.8%
and T10■ are added in an amount of 0.1 to 2.0%.

Further, the ultraviolet-shielding glass fiber composition for printed wiring boards of the present invention is preferably a low dielectric constant glass fiber composition 1 having a dielectric constant of 4.5 or less at the frequency IMZ at room temperature.
00% by weight, Fe2O3 is 0.45 to 0.45% by weight
1.5% and TiO. is added in an amount of 0.2 to 1.5%.

The reason why the contents of Fe2O3 and TiO2 are limited as described above in the present invention is as follows.

Fe2O3 is a component that gives ultraviolet absorbency to glass, and its content is 0.1-1.8%, preferably 0.45%.
~1.5%. If it is less than 0.1%, the ultraviolet absorbing property is insufficient, and if it is more than 1.8%, the dielectric constant increases greatly, the coloring of the glass becomes significant, and heat ray absorption becomes significant, making it difficult to melt the glass. Become.

TiO■ is a component that coexists with Fe2O3 and gives the glass ultraviolet absorbency and suppresses the absorption of ultraviolet rays in the visible and infrared regions, and its content is 0.1 to 2.0%, preferably 0.2%. ~1.5%. The content of T1o2 is 0.
If it is less than 1%, the above effects cannot be obtained, and if it is more than 2.0%, absorption of ultraviolet rays in the visible region becomes significant, causing coloring of the glass and increasing the dielectric constant.

Further, the low dielectric constant glass fiber composition used in the present invention has a dielectric constant of 4.5 or less at a frequency of I MHz at room temperature, and more specifically, S10270.0 in weight%.
~80.0%, AI2O3 0 ~2.0%, B2O
312.0%, Na2O0~3.0~21.5%, M
g0 0-1.0%, CaO2~2.0%, L12
O 0 ~2.0%, Na2O 0 ~3.0%, K2
O0 ~ 3.0%, L12O+Na2O+K2O2
．． It has a basic composition of 0 to 2.0% and Na2O of 0 to 3.0%.

[Example code] Next, the present invention will be explained in more detail based on examples.

The following table shows the Fe2 of each sample of the example of the present invention and the comparative example.
O3 and T10 content and wavelength 380nm 1400n
m and transmittance at 500 nm and frequency 1 at room temperature
It shows the value of dielectric constant in MHz.

Each sample in the table was prepared as follows.

First, weight% TeSlo. 76%, B2O32O%, Mg
O O. 5%, Ca0 0.5%, Li2O 0.5%
, Na2O 1.5%, K2Ol. Fe2O3 and TiO2 for a low dielectric constant glass fiber composition consisting of θ%
Glass raw materials were prepared so as to form a glass in which was added in the proportions shown in the table, and melted at 1550° C. for 16 hours using a platinum crucible. After melting, the melt was poured onto a carbon plate, formed into a plate shape, and slowly cooled. Then 30X IOX 5mn
A sample piece was prepared by optically polishing both sides to a + size, and the transmittance was measured using a spectrophotometer. Add the remaining sample to 5
It was polished into a plate shape of 0x50x3+am, and the electrical conductivity at a frequency of I MHz at room temperature was measured.

Margin below? As is clear from Fe2O. and Comparative example NO. containing no TiO2. Sample No. 5 has a good dielectric constant of 4.5 or less, but has a high transmittance of 88% or more at wavelengths of 380 nm to 1400 nm, indicating that it hardly blocks ultraviolet rays. On the other hand, NO. The samples of Examples 1 to 4 had a transmittance of NO. 1 at 400 nm while keeping the dielectric constant at 4.5 or less. It decreased to 1/10 or less of that of sample No. 5, and has sufficient ultraviolet shielding properties. However, Fe
Comparative example No. 2O3 and TiO■ were added in large amounts. In sample No. 6, the transmittance increased to 4.5 or more, and at the same time the transmittance in the visible region, that is, at 500 tv, decreased to almost zero. It can be seen that the coloration is remarkable compared to Examples 1 to 4.

[Effects of the Invention] As described above, the glass fiber composition for printed wiring boards of the present invention has a dielectric constant of 4 at the frequency I Mllz at room temperature.
．． 5 or less, it is suitable for strengthening printed wiring boards that require high-speed signal processing, and it also has the desired ultraviolet shielding properties without causing coloration or heat ray absorption.
It becomes possible to form a solder resist pattern using a photoprinting method with simultaneous exposure on both sides, and production efficiency in manufacturing printed wiring boards can be greatly improved.

Claims (3)

[Claims] (1) Dielectric constant at room temperature and frequency 1MHz is 4.5
It is characterized in that 0.1 to 1.8% by weight of Fe_2O_3 and 0.1 to 2.0% by weight of TiO_2 are added to 100% by weight of the following low dielectric constant glass fiber composition. UV-shielding glass fiber composition for printed wiring boards. (2) The dielectric constant at a frequency of 1 MHz at room temperature is 4.5
It is characterized by adding 0.45 to 1.5% by weight of Fe_2O_3 and 0.2 to 1.5% by weight of TiO_2 to 100% by weight of the following low dielectric constant glass fiber composition. An ultraviolet-shielding glass fiber composition for printed wiring boards according to claim 1. (3) Low dielectric constant glass fiber composition is SiO_2 by weight%
70.0-80.0%, Al_2O_30-2.0%,
B_2O_315.0-21.5%, MgO0-1.0
%, CaO0-2.0%, Li_2O0-2.0%, N
a_2O0-3.0%, K_2O0-3.0%, Li_
The ultraviolet-shielding glass fiber composition for printed wiring boards according to claims 1 and 2, which has a basic composition of 2.0 to 5.0% of 2O+Na_2O+K_2O.