JPS6362393A - Flame-retardant circuit board - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Field of Application] In general, paper/phenol substrates are the mainstream substrate materials for consumer use, and glass/epoxy substrates are the mainstream substrate materials for industrial use. With the advancement of semiconductor technology, the demand for printed wiring boards is increasing, and higher performance is also required.

Conventionally, it has been known to introduce hollow spheres into a circuit board to obtain a board with a low dielectric constant. (Tokuko Sho 57-1B353@
). Furthermore, a circuit board formed by laminating a resin layer containing hollow spheres, a layer consisting of resin and a base material, and steel foil has already been proposed in JP-A-60-167394. In addition, in order to obtain a uniform and thick sheet from a resin composition in which fillers such as hollow spheres having different specific gravities are mixed, Japanese Patent Application Laid-Open No. 61-10430 and Japanese Patent Application No. 60-8
7164 is useful.

In order to impart flame retardancy to resins, it has long been known to empirically add or react with phosphorus compounds, bromine compounds, and chlorine compounds. It is also known that adding antimony trioxide as an auxiliary agent has a synergistic effect (for example,
Industrial Materials Volume 21, No. 4. APR (1973)
See page 7>.

As described above, by introducing hollow spheres into the resin, a board with excellent dielectric properties, which is the most important performance of a printed circuit board, can be obtained.

[Problems to be Solved by the Invention] However, the conventional technique of simply adding hollow spheres to resin as fillers has the disadvantage that satisfactory performance as a circuit board other than dielectric properties, especially flame retardance, cannot be obtained. was there.

Inside the hollow sphere is nitrogen, which is usually a nonflammable gas, or
Although carbon dioxide gas is contained, when a composition containing hollow spheres is exposed to a flame, the apparent surface area of the resin increases, making it more likely to burn.

Furthermore, when a large number of hollow spheres are introduced, the viscosity of the mixed resin increases, resulting in poor processability into resin plates.

As mentioned above, it was very difficult and rare to make a resin composition into which hollow spheres were introduced flame retardant and thereby satisfy the flame retardant standards for the substrate.

Therefore, the present invention has been made based on the results of considering the manufacturing method when introducing hollow spheres into a circuit board, and examining a method for providing sufficient flame retardance while satisfying various important characteristics for the board. It has been reached.

[Means for Solving the Problems] The present invention has the following configuration in order to eliminate the drawbacks of the prior art.

That is, the present invention provides a circuit board in which composite layers of a resin composition and a textile base material are formed on both sides of a core layer, and steel foil is further adhered to the surface of each composite layer, the circuit board comprising: The core layer is made of a composite material of a resin composition mainly composed of brominated epoxy resin and micro hollow spheres, and the content of the micro hollow spheres is 40 to 60%. It relates to circuit boards.

Examples of the microscopic hollow spheres include those made of inorganic substances such as alumina, silica, zirconia, glass, and shirasu, and those made of phenolic resin. For example, product names include Phyllite (Nippon Phyllite), Shirasu Balloon (Sanki Kogyo), and Ecosphere (EHER3ON C).
UHING INC, ), Glass Bubbles (3M Company),
Examples include phenol balloons (UNIONCARBIDE). As for the characteristics of the hollow sphere, one having a diameter of 10 to 200 μm and one having a bulk specific gravity of 0.2 to 0.8 are used in view of its strength and dielectric constant.

The core layer composed of micro hollow spheres and a resin composition described in the present invention will be referred to as a core sheet hereinafter.

Examples of the resin for the core sheet include thermosetting resins such as bromine-containing phenol resins, epoxy resins, furan resins, unsaturated polyester resins, xylene resins, alkyd resins, sulfonamide resins, and melamine resins.

There are various ways to introduce bromine. For example, any method such as brominating the base agent, brominating the curing agent, or adding a bromine-containing compound can be used.

The bromine content is 10-3 based on the total weight of the core sheet resin composition, that is, the main resin, curing agent, and a small amount of catalyst.
0% by weight is preferred.

The content of hollow spheres in the core sheet is suitably 40 to 60 in volume percentage in view of the properties and workability of the core sheet obtained. If the amount of the resin composition exceeds this range, the resin and the hollow spheres are likely to separate, and if the content of the hollow spheres exceeds this range, the viscosity of the hollow spheres will become too high, making handling difficult.

A uniform core sheet without warping can be prepared by referring to Japanese Patent Application Laid-Open No. 61-010430@ and Japanese Patent Application No. 60-87164.

Antimony trioxide is preferably pulverized to an average particle size of 1 μm or less, for example, fine particles manufactured by Kingdom Seiren Co., Ltd. It can be added to the resin composition by following the usual method, but be sure to disperse it thoroughly. Therefore, it is preferable to further pulverize the powder using a three-roll mill or the like.

The amount of antimony trioxide added is preferably 1 to 5 parts by weight based on the resin composition for the core sheet. This is because if it is smaller than 1, the flame retardant effect will be small, and if it is larger than 5, problems such as separation may occur, resulting in inconvenience in terms of work.

The composite layer of the resin composition and the textile base material will hereinafter be referred to as prepreg. The resin composition for the prepreg may be the same as or different from the resin composition for the core sheet. From the standpoint of flame resistance, bromine-containing compositions are also preferred.

As the textile base material, a textile made of glass fiber, synthetic fiber, natural fiber, etc. is used. The impregnation method is the usual method,
That is, a method is adopted in which a base material is continuously immersed in a resin solution and then continuously heated and dried.

Steel foils with thicknesses of 9.18 and 35.70 tim are often used.

[Example] Bromine-containing liquid epoxy resin (diglycidyl ether of tetrabromobisphenol A, diglycidyl ether of glycidol, diglycidyl ether of polyhydric alcohol, curing agent "Epiclompa B650" (Dainippon Ink)
Co., Ltd.), dimethylbenzylamine) (both are liquid at room temperature) as a resin component, and this resin component and an average diameter of 6
Hollow sphere with a diameter of 0 μm and a specific gravity of 0.38 (“glass bubble”)
33B/4000, manufactured by 3M Company) were mixed at a predetermined volume ratio. Note that the epoxy resin 3 above contains bromine.
Controlled by changing the ratio of ingredients.

Antimony trisunide (fine particles) manufactured by Kingdom Seiren Co., Ltd. was sufficiently dispersed in "Epicoat" 828 (Yuka Shell Co., Ltd.) using three rolls to form a 60% (by weight) paste. A predetermined amount of this paste was added to the above components to prepare a resin mixture.

After vacuum defoaming of this mixture,
Using the vertical double belt device shown in Figure 1 of No. 7,
It was pushed out through a slit between rotating belts.

Then, while running in the vertical direction, the belt temperature was increased to 150'.
C. After curing for 30 minutes, a flat plate was removed from between the double belts with a clearance of 1.2 mm to obtain a 1.2 mm resin sheet. This material had no fluidity at all even when heated to 130° C. and was in a so-called C-stage state.

Next, 80% each of ``Epicoat'' 1045 (brominated epoxy resin, solid at room temperature), ``Epicoat'' 154 (phenol novolak type epoxy resin, liquid at room temperature), dicyandiamide (DICY), and methyl cellosolve were added.
0.20.4.100 parts were mixed, and this was impregnated into a glass cloth (manufactured by WE1BK Nichizuka Spinning Co., Ltd.) using a conventional method to create a B-stage prepreg.With the resin sheet in the center, two sheets of prepreg and a steel foil were mixed. Stack two sheets and heat to 160'.
C. A substrate having the cross section shown in the drawing was produced by hot pressing at a pressure of 35 kg/- for 30 minutes.

The thickness was 1.5 mm. The obtained substrate had a small thickness area, and no peeling or blistering was observed when immersed in a 260° C. solder bath.

Among the evaluations, flame resistance was determined according to JIS 6911 vertical method (UL
-94), and if -0, mark ○, V
If -O was not satisfied, it was distinguished by an X mark. Workability directly refers to viscosity, and if the viscosity of the resin/hollow sphere mixture is low and easy to work with, and the hollow spheres and antimony trioxide do not separate, it is marked with an ○, and if not, it is marked with an X. The performance of the substrate directly indicates the dispersibility of the hollow spheres and antimony trioxide in the substrate, and those with good dispersibility are marked with an ○ and those with poor dispersibility are marked with an X.

Table 1 shows the evaluation results of the obtained circuit board with a thickness of 1.6 mm. As can be seen from the table, results satisfying all of the flame retardance, workability, and substrate performance were obtained under the conditions proposed in the present invention.

[Effects of the Invention] By considering the ratio of hollow spheres to the resin composition and the bromine content of 1 m, the present invention has sufficient flame retardancy while satisfying various characteristics such as workability and substrate performance. The present invention provides a circuit board.

[Brief explanation of the drawing]

The drawings show an example of a circuit board according to the present invention. Its components are a steel foil 1, a resin 2, a base material 3, a resin 4, and a hollow sphere 5. Patent Applicant Higashi Shi Co., Ltd. Company Procedure Ne City Official Book 1, Indication of Case Patent Application No. 205945 of 1985 2, Name of Invention Flame Retardant Circuit Board 3, Person Making Amendment Relationship with Case Patent Applicant Address 2-2 Nihonbashi Muromachi, Chuo-ku, Tokyo Name (3
15) Toshi Co., Ltd. 5. Number of inventions increased by amendment None In the specification (1) The scope of claims will be amended as shown in the attached sheet. (2) On page 4, line 13, r60% is expressed by J as “60
Correct the fact that it is % (volume) with J. Claims (1) A circuit board formed by forming composite layers of a resin composition and a textile base material on both sides of a core layer, and further adhering steel foil to the surface of each composite layer, The first core layer is made of a composite material of a resin composition mainly composed of brominated epoxy resin and micro hollow spheres, and the content of the micro hollow spheres is 40 to 60.
% (volume) flame retardant circuit board. (2) The flame-retardant circuit board according to claim (1), wherein the core layer contains 1 to 5 parts by weight of antimony trioxide based on the resin composition. (3) The flame-retardant circuit board according to claim (1), wherein the core layer contains 10 to 30% by weight of bromine based on the resin composition. Showa 62.Tan 15th??r5'FITFzS' RFB F'fJ M V
1. Indication of the incident 1985 Patent Application No. 205945 2. Name of the invention Flame-retardant circuit board 3. Changed name of the person making the amendment (315) Toshi Co., Ltd. 5. Number of inventions increased by the amendment None. 6. Insert "The present invention relates to a circuit board with excellent flame retardancy. [Prior art]" in (1) page 1, line 20 of the specification subject to amendment.

Claims (3)

[Claims] (1) A circuit board formed by forming composite layers of a resin composition and a textile base material on both sides of a core layer, and further adhering steel foil to the surface of each composite layer, wherein the core layer is , is made of a composite material of a resin composition mainly composed of a brominated epoxy resin and micro hollow spheres, and the content of the micro hollow spheres is 40 to 6
A flame retardant circuit board characterized by having a flame retardance of 0%. (2) The flame-retardant circuit board according to claim (1), wherein the core layer contains 1 to 5 parts by weight of antimony trioxide based on the resin composition. (3) Claim (1) characterized in that the core layer contains 10 to 30% by weight of bromine based on the resin composition.
) The flame-retardant circuit board described in item 2.