JPH0119202B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A number of insulating boards are known for printed wiring boards and other uses. Common printed wiring boards often have different dielectric constants when measured in different directions of the board. This arises from the need to take into account the desired physical properties and dielectric constants achieved by the typical materials used in printed wiring boards.

For example, Special Publication No. 12207, No. 47-12207, Special Publication No. 42-
As described in Publication No. 18159, insulating paper or laminated insulating materials formed by impregnating and curing insulating paper with resin have been considered, but due to the materials used, both of these are isotropic dielectrics. It did not have a specific rate. Furthermore, the insulated wire described in Japanese Utility Model Publication No. 46-14122 uses hollow fibers coated with adhesive paint as its coating layer, and since hollow fibers are used, this coating layer also has the following properties: It did not have a tropic dielectric constant.

Therefore, a truly isotropic printed wiring board having substantially the same dielectric constant when measured in all or any direction has long been highly desirable.
This has been achieved in some cases using alumina in printed wiring boards. However, the use of alumina resulted in plates that were expensive, difficult to machine, and brittle, making them unsuitable for many applications.

It is an object of this invention to provide a composite polymeric insulating board useful as a printed wiring board that exhibits isotropy with respect to dielectric constant and tangent loss, and that can be adapted to have any preselected dielectric constant over a wide range. That's true.

Another object of the invention is to provide a reinforcement and an impregnated weight compound therein in accordance with the above object to provide mechanical strength, making it possible to obtain an insulating board with good mechanical properties for use as a printed wiring board. It is an object of the present invention to provide an insulating plate having a coalescent material.

Yet another object is to provide a method for manufacturing an insulating board according to the above object.

This invention comprises: (a) a reinforcing fiber material made of a polyolefin material; (b) a polybutadiene having a dielectric constant very close to that of the reinforcing fiber material and impregnated into the reinforcing fiber material and cured. Provided is an insulating plate made of a material having an isotropic dielectric constant and an isotropic tangent loss substantially free of air, and a method for manufacturing the same.

The feature of this invention is that a reinforcing fiber material is impregnated with a polybutadiene material having a dielectric constant very close to that of the material, and when polymerized and cured in a deaerated state, an isotropic dielectric constant and an isotropic dielectric constant are obtained. It is based on the knowledge that an insulating plate with tangential loss can be obtained.

The insulating board of the present invention includes polypropylene, polyethylene, and
It has a polymer fiber material (reinforcing fiber material) made of a polyolefin material containing polytetrafluoroethylene and its copolymer. Second
The reinforcing layer is impregnated with a polymeric material having a dielectric constant very close to that of the reinforcing layer, preferably within ±1 of the dielectric constant of the polymeric layer of the fibrous material. The dielectric constants of the reinforcing polymer layers, polyethylene, polypropylene, and polytetrafluoroethylene, are all very close to that of polybutadiene, and no matter which reinforcing polymer layer is combined with polybutadiene, the dielectric constant and It can be used to obtain isotropic tangent loss. The overall dielectric constant of the insulating plate is isotropic, preferably in the range from 2.2 to 20 when measured in any or all directions at a temperature of 25° C. and 60 cycles. The insulating plate is 0.0009 or more when measured at 8.5 kilomegacycles (GHz), 23°C, and 50%RH.
Preferably it has a tangent loss in the range of 0.01.

The tangent loss or dielectric constant can be tailored to suit the particular application. The reinforcing fiber material is selected from the group consisting of polypropylene, polyethylene, polytetrafluoroethylene and copolymers containing these olefin polymers as a main component. The polymer impregnated into and formed around the reinforcing material is preferably polybutadiene or a butadiene copolymer with a small amount of other monomer (preferably an unsaturated vinyl monomer). Fillers can also be added to the impregnated material prior to its polymerization so that either the dielectric constant or the tangent loss is different from that of an insulating board containing pure polymeric impregnated material and polymeric fiber reinforced material. However, fillers are used only to preselect one or the other of dielectric constant and tangent loss.

If it is desired to change the dielectric constant or tangent loss, this can be done using fillers. The filler is inert and does not participate in the exothermic reaction of the impregnated polymer during curing around the fiber material.

A feature of this invention is that a wide range of dielectric constants and tangent losses are obtained in an insulating plate with good mechanical properties, and the insulating plate of this invention has a wide range of applications. Isotropy with respect to both dielectric constant and tangent loss is particularly important when the insulating plate is used as a substrate for an antenna such as a phased array or as a common printed wiring board.

Referring to the drawings, the insulating board of the present invention is indicated at 10 in FIG.

The overall length and width of the insulating plate can vary widely depending on the particular application known. Thickness likewise depends on the particular application. For example, the insulating plate can be 0.004 inch to 1 inch or more thick. For most applications, insulation plate 0.05
~0.1 inch thick. When thickness greater than 0.05 inch is required, it is preferable to use composite board;
For example, as shown in FIG.
It is used with. Of course, any number of fiber layers can be used with the impregnating material to make it as thick as desired. The insulating plate can have a layer of copper, aluminum or other metals, for example by forming or subsequently applying the copper layer 18 or by directly applying the insulating plate onto a pre-formed metal sheet. You can also make one. The insulation board is etched,
It can be processed into a circuit board using known techniques including masking.

The fiber material used as the reinforcing material is preferably a non-woven polypropylene fiber material. In some cases, woven or chopped fiber materials are used as reinforcing fiber materials. Preferably, the fibers are evenly distributed throughout the finished board. Other olefins, such as polyethylene and polytetrafluoroethylene or copolymers of these olefins with each other or with other monomers, may also be used in fiber-forming capacity. Polypropylene is preferred as it provides the desired mechanical strength and has a dielectric constant within the desired range very close to that of the impregnated polymer. An important feature of this invention is that the impregnating agent, when polymerized and cured, has a dielectric constant very close to that of the reinforcing material. It is preferable that the dielectric constants of both are within ±1 of each other, and in the case of polybutadiene and polypropylene, the dielectric constants of the two are within the range of ±1.
It is within 0.7.

In preferred embodiments, the reinforcing fibrous material is a non-woven fabric, such as
Made by Perlon Corporation, thickness 0.002 ~
The Pelon consists of a 0.025 inch polypropylene butt. Weight of 30g/ ^m2 , approx. 0.009
A particularly preferred material is Pellon N1251F, which has a thickness of 1 inch, a breaking strength of 5 pounds, an elongation of 22%, and a wicking rate of 40 seconds/inch in 30% KOH.

The impregnating polymer matching Peron's dielectric constant is polybutadiene, polymerized alone or with other monomers, preferably vinyl unsaturated monomers, and may contain fillers.

For use as the impregnation polymer, high vinyl 1-2 liquid polybutadiene, such as those manufactured by Colorado Chemical Specialties, Golden, Colo., consisting of polybutadiene and having a microstructure of 70±5% 1.2-vinyl and an average molecular weight of about 2050±200, is used. death,
Viscosity 40000 ± 10000, specific gravity 0.89, bulk density approximately 7.4, measured with a Burdskfield viscometer at 23°C in CPS
Ricon 150 (dielectric constant at 8.5GHz, 23°C) with pounds per gallon and intrinsic viscosity 0.105±0.06
2.38, tangent loss 0.003) is preferred. Other polybutadienes may also be used. Preferably, the polybutadiene is finally cured or polymerized after being impregnated into the reinforcing material.

Polybutadiene compositions are formulated with comonomers such as vinyl unsaturation such as styrene, vinyltoluene, t-butylstyrene, alpha-methylstyrene, monochlorostyrene, i-butyl methacrylate, methyl methacrylate, diallyl phthalate, diallyl maleate. It can also have a monomer. Preferably, substantially pure polybutadiene is used, and in all cases at least 50% by weight of any final copolymer is polybutadiene. Although it is preferred to include a known crosslinking agent to shorten the curing time, it may be omitted in some cases. Peroxide curing or other conventional curing methods such as radiation irradiation may be used.

Crosslinking agents include divinylbenzene, trimethylolpropane, trimethacrylate, 1,3-
Butylene dimethacrylate. Known organic peroxide catalysts are also used for curing. Such catalysts include benzoyl peroxide, methyl ethyl ketone peroxide, di-t-butyl peroxide, α,α'-bis(t-butyl peroxide)
There is diisopropylbenzene.

Curing can also be done using small amounts of other compounding agents. In all cases, the final product is a thermoset polybutadiene polymer material. In addition to maintaining the physical properties of the final cured product, it is important to maintain isotropy with respect to tangent loss and dielectric constant over a wide range of operating frequencies and other conditions. Desired physical properties include high strength, moderate flexibility, good support for conventional printed wiring and antenna materials, and other desirable physical properties known for printed wiring boards.

In some cases it is advantageous to adapt the dielectric constant and/or the tangent loss to the desired values, and various fillers are used for this purpose. Preferred fillers include polyethylene, polytetrafluoroethylene, alumina, barium titanate, titanium dioxide and strontium titanate. Other fillers can of course also be used. Fillers can be used to increase the dielectric constant needed to balance the properties of the material throughout the board. Fillers can also be used to adjust the tangent loss of the material. Generally, the insulating plate of the present invention can be designed to meet a predetermined dielectric constant or a predetermined tangent loss by selecting the amount and type of filler used. However, it is generally not possible to preset both values by adding one type of filler. Therefore, although either the tangent loss or the dielectric constant to be set is selected and the desired amount of filler is added to obtain the set value, it is not possible to obtain the other value that was not selected. In all cases, the filler is inert during the chemical reaction that hardens the impregnating material around the reinforcing material. The filler is preferably in the form of submicron-sized particles and should not account for more than 95% by weight of the total composition.

The insulating plates of this invention are generally made by mixing butadiene monomer in low polymerized butadiene together with a catalyst and one or more comonomers (if used). Similarly, if fillers are used, they are premixed with the monomers. Preferably, each component is homogeneously distributed. Select a reinforcing textile material and cut to size. The resin and catalyst mixture is poured into the reinforcing material and thoroughly absorbed. If more than one layer of reinforcing material is used, multiple layers are stacked until the desired number of layers and desired thickness are obtained. Finished thickness generally
One reinforcing layer 0.007 inch thick is used every 0.010 inch. The layer of absorbed reinforcement is placed in a degassing chamber to remove all air and thoroughly wet the reinforcing fiber layer. Impregnated reinforcing fiber layer 275~300〓
Press in a press to remove air and cure preferably for 30 to 2 hours. The complete molded article exhibited thermoset morphology, substantially homogeneous, and isotropic with respect to dielectric constant and tangent loss.

Example 1 100 g of Recon 150 was used as a catalyst (Lepersol 101 manufactured by Leucidol Corporation,
This is a peroxide catalyst with a boiling point of 119°C and suitable for high temperature curing of polybutadiene). After preparing the mixture, 30 g of it was transferred to a Peron sheet (0.0080 inch thick, 10 inch straight, 10 inch wide (weight 8.34 g) with a dielectric constant of 2.2 at 8.5 GHz and 23°C).
0.0005). After sufficient absorption, stack the sheets and put them in a deaeration chamber to remove all the air.
Wet the fabric completely. The impregnated fabric is placed in the press at room temperature and the press is lowered to the stop to determine the thickness.
It was made into a 0.025 inch finished product. The product was held in a press at 285° for 1 hour to obtain a final product insulating plate having a dielectric constant of 2.3 at 8.5 GHz and 23°C. The tangent loss of the insulating plate was 0.002 at 8.5 GHz and 23°C. Here, silicon 150 has a dielectric constant of 2.38 at 8.5GHz and 23℃.
The tangent loss was 0.003. These values are recon 150
This is the value when only the material is cured. The insulating board showed good mechanical properties for use as a printed wiring board. The insulating plates had some flexibility and maintained their physical properties while withstanding temperatures up to at least 275 degrees Celsius. The insulating plate was a thermoset composite material and exhibited isotropy in terms of tangent loss and dielectric constant.

Example 2 Example 1 was repeated, but 56 g of the Recon-Liupazol mixture was mixed with 144 g of powdered strontium titanate to obtain a homogeneous mixture. 140 grams of the mixture was impregnated into four sheets of Perron sheet used in Example 1, molded and cured as in Example 1 to yield a final product 0.040 inch thick. 8.5GHz, 23
The dielectric constant at ℃ was 10, 8.5GHz, and the tangent loss at 23℃ was about 0.0032.

Example 3 Example 1 was repeated but with 40 g of recon
The Pasol mixture was further mixed with 160 g of strontium titanate. 150 g of this mixture was spread over three Perron 1251F sheets (8.5 GHz, dielectric constant 2.2 at 23°C,
Impregnated with tangent loss 0.0005). Three sheets of Perron were cured in a mold stacked on top of each other as described above. The final product exhibited a dielectric constant of 16 and a tangent loss of approximately 0.0029 at 85 GHz and 23 °C, respectively.

Example 4 Example 2 was repeated, but using 155 g of barium titanate (BaTiO ₃ ) instead of 144 g of strontium titanate. The insulating plate had good mechanical properties and a dielectric constant of 10 and a tangent loss of about 0.008 at 8.5 GHz and 23 °C, respectively.

In all of the above examples, the dielectric constant and tangent loss of the resulting products were isotropic.

When any of the compositions of Examples 1 to 4 is formed by placing it in the form of an impregnated sheet on a copper layer, the impregnated polymerizable material polymerizes and adheres closely to the copper;
As shown in FIG. 2, an integrated printed wiring board suitable for etching could be formed.

Although particular embodiments of the invention have been described, many modifications are possible. In all cases, the resin, fibers and particulate filler must be matched to give the resulting insulating board the desired dielectric constant or tangent loss. Both the impregnated thermoset material and the reinforcement layer are subjected to operating temperatures e.g. 60 cycles/sec and 23
It is necessary to have a dielectric constant of 3 or less and a tangent loss of 0.002 or less at ℃. In all cases, the final insulation board has a dielectric constant of 3 or less, unless filled with an impregnating polymeric material, and has a dielectric constant of at least 3 without melting.
Can withstand continuous operating temperature of 135℃. The polyolefin reinforcing layer is preferably a non-woven fibrous material that swells or is otherwise evenly distributed throughout the insulation board from top to bottom to provide homogeneity. Mats of Peron or similar materials are preferred because they allow the fibers to swell and provide a substantially homogeneous distribution. Such fibers often have at least 1/
It has a length of 8 inches and a diameter of less than 0.001 inch, although these dimensions may vary.

The dielectric constant and tangent loss of any particular material are
Of course, it varies somewhat depending on the frequency at the time of measurement. The stated values are for the operating frequency and temperature. Often this variation is small, for example the dielectric constant of polypropylene reinforced pine is 2.2 at 60 cycles, ¹⁰³ cycles and ¹⁰⁶ cycles, but the tangent loss (tanδ) is approximately
0.0005, 10 ³ cycles and 0.0008, 10 ⁶ cycles
It is 0.0018. Polybutadiene has a dielectric constant of approximately 2.9 at 60 cycles, 2.78 at 10 ⁶ cycles, and 2.9 at ^{10 10} cycles when measured at 23°C, and a tangent loss (tan δ) of 0.0001 at 60 cycles and 2.9 at 10 ⁶ cycles.
0.0029, 0.004 for 10 ¹⁰ cycles. When these materials are combined in this invention, the entire insulating plate has a dielectric constant of 10 to 2.315 at ¹⁰ cycles and a tangent loss of 0.0015.
gave.

Polymerizable impregnated material is 70~ for reinforcing material
Consisting of 98wt% binder and reinforcing material 2~
It is preferable because it is 30wt%. The insulation plate is 0.005 to 1 inch thick.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an insulating plate of the present invention. FIG. 2 is a cross-sectional view of a variant having an outer layer of copper for use as a printed wiring circuit member.

Claims (1)

[Scope of Claims] 1 (a) a reinforcing fibrous material made of a polyolefin material; (b) a reinforcing fibrous material having a dielectric constant very close to the dielectric constant of the reinforcing fibrous material, impregnated with the reinforcing fibrous material and hardened; An insulating plate having an isotropic dielectric constant and an isotropic tangent loss with substantially no air mixed therein. 2. The insulating board according to claim 1, wherein the polyolefin material is made of polypropylene, polyethylene, polytetrafluoroethylene, or a copolymer thereof. 3. The reinforcing fiber material and the polybutadiene material each have a dielectric constant of 3 or less at 60 cycles at 23°C, and have a dielectric constant in the range of 2.2 to 20 at 60 cycles at 25°C, making them suitable for printed wiring boards. An insulating plate according to claim 1. 4. The insulating board according to claim 1, wherein the polybutadiene material contains a filler that is inert to the curing of the polybutadiene material. 5. The insulating board according to claim 4, wherein the filler is selected from the group consisting of polyethylene, polytetrafluoroethylene, alumina, barium titanate, titanium dioxide, and strontium titanate. 6. The insulating board according to claim 4, wherein the polybutadiene material is a copolymer of butadiene monomer and a small proportion of unsaturated vinyl monomer. 7. The insulating plate according to claim 3, which has a tangent loss in the range of 0.009 to 0.01 at 8.5 GHz and 23°C. 8. Claims 2 to 7, wherein the polybutadiene material contains a uniform distribution of an inert filler that changes the dielectric constant of the insulating plate without impairing its isotropy.
Insulating plate described in any one of the items. 9. The insulating board according to any one of claims 2 to 8, wherein the insulating board is overlaid with a copper layer. 10 The polybutadiene material is 70-90% by weight of the insulation board, and the insulation board is 2.2-20% by weight at 25℃ for 60 cycles.
Claim 1 having a dielectric constant in the range of
Insulating board as described in section. 11. impregnating a reinforcing fiber material selected from the group consisting of polypropylene, polyethylene, polytetrafluoroethylene and copolymers thereof with a butadiene monomer having a dielectric constant very close to that of the fiber material in the polymerized state; A method for producing an insulating board having an isotropic dielectric constant and an isotropic tangent loss, comprising the steps of substantially removing internal air and polymerizing and curing a butadiene monomer in a fibrous material. 12. The method for manufacturing an insulating board according to claim 11, which includes the step of uniformly mixing an inert filler into the reinforcing fiber material before impregnating the butadiene monomer into the monomer.