JPH05311010A - High-permittivity composite substrate - Google Patents

Abstract

PURPOSE:To obtain the high-permittivity substrate which is small and excellent in dielectric characteristics and moldability and is useful for an electronic apparatus, an information apparatus, etc., by mixing a polyolefin with a ceramic deriv. powder and molding the resulting mixture. CONSTITUTION:The substrate is produced by mixing a polyolefin (pref. a thermoplastic resin having an epsilonr of 2.2/10<6>Hz-3.0/10<6>Hz and a tan delta lower than 10<-2>/10<6>Hz) with a ceramic deriv. powder (pref. one having an epsilonr higher than 30 and a tan delta lower than 1X10<-2> in the frequency range of 10<6>-10<9>MHz) and molding the resulting mixture. Since the substrate exhibits desired dielectric characteristic without detriment to the excellent dimensional accuracy and moldability inherent in the mixture, it can be made small with a high accuracy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite high dielectric constant substrate used in electronic equipment, information equipment and the like.

[0002]

2. Description of the Related Art In recent years, the frequency band used in the field of electronic devices and communication devices is shifting to a higher frequency region with the rapid increase in the amount of communication information due to the shift to an advanced information society. Especially mobile communication such as mobile phones and car phones,
For satellite broadcasting and satellite communication, high frequency signals in the UHF band from the megahertz to the gigahertz band are used. On the other hand, a mobile phone, which is a typical example of the above-mentioned device, had a capacity of 400 ml and a weight of 600 g several years ago, but has recently been 15
The size tends to be drastically reduced to 0 ml and 230 g. In order to respond to the miniaturization of electronic circuits in such a high frequency region, the substrate used for the transceiver must be a material having both excellent high frequency transmission characteristics and high dielectric constant.
That is, transmission energy loss called dielectric loss is inevitably generated in the circuit. The dielectric loss is proportional to the product of the frequency and the dielectric loss tangent of the substrate (hereinafter referred to as tan δ). Also,
In the high frequency region such as UHF, tan δ has a strong tendency to increase as the frequency increases. From the above, in order to make the dielectric loss as small as possible, it is necessary to make tanδ as small as possible (low). On the other hand, in the substrate, the high frequency wavelength (λ) is shortened in inverse proportion to the dielectric constant of the substrate (hereinafter referred to as ε _r ) as shown in equation (1) with respect to the original wavelength (λ ₀ ), It can be seen that the larger the ε _{r of the} substrate, the smaller the size can be. λ = λ ₀ / √ε _r (1) As mentioned above, as a substrate for small equipment intended to be used in a high frequency region, a material having a large ε _r (high) and a small tan δ (low) is used. is necessary. On the other hand, high dielectric constant substrates (hereinafter abbreviated as substrates) include substrates made of inorganic materials (hereinafter abbreviated as inorganic substrates) and substrates made of organic materials (hereinafter abbreviated as organic substrates). Dielectric ceramic substrates such as oxide-based and perovskite-based substrates are known as inorganic substrates, and cyanoethyl cellulose-based resin substrates and the like as organic substrates.

[0003]

The characteristics of high dielectric constant ceramics substrates are generally ε _r = ~ 100/1 MHz, ~ 100.
/ GHZ, tan δ = 10 ^-2 to 10 ^-4 , showing excellent characteristics. The production is performed by firing an unfired sheet (green sheet). However, since it is hard after firing, it is difficult to make holes, cuts, and cuts, which are important as a substrate. Therefore, press holes are punched and cut at the green sheet stage,
It is difficult to keep the dimensional accuracy, which is indispensable for high-frequency circuit boards, within ± 5% due to the large dimensional shrinkage in the firing process, and it is not possible to sufficiently meet the demand for high-precision and high-density circuits. .. Furthermore, it has the disadvantages of high specific gravity and brittleness. On the other hand, as an organic substance with a large value of ε _r ,
For example, cyanoethyl resin-based materials have ε _r = 15-
20/10 ⁶ Hz, but tan δ> 10 ⁻² / 10 ⁶ Hz, and it is difficult to obtain a low tan δ substrate. Also, because the manufacturing of the substrate must start with a low viscosity solution,
It also has a drawback that it takes time to manufacture a substrate having a thickness of mm or more. On the other hand, recently, a polyphenylene oxide resin substrate has been proposed as seen in Japanese Patent Laid-Open No. 1-245053. This substrate contains polyphenylene oxide, a three-dimensional crosslinkable monomer and ceramic powder. Since this substrate starts from a solution system and is accompanied by cross-linking due to the limitation of the manufacturing process, it has a problem of moldability similar to the case of manufacturing a high dielectric constant ceramics substrate.

As described above, since the conventional high dielectric constant substrates each have some drawbacks, it has been strongly desired to develop a new high dielectric constant substrate which is suitable for small equipment and is easy to mold. The present invention is to solve the above-mentioned conventional problems, and has a desired high ε _r and low tan δ, and also has a high dielectric constant using a resin composition that is easy to handle and mold in small equipment. It is intended to provide a substrate.

[0005]

As a result of intensive studies in view of the above circumstances, the inventors of the present invention have found that the above object can be achieved by using a polyolefin polymer and a ceramic dielectric powder. The present invention has been completed. That is, the present invention relates to a composite high dielectric constant substrate formed by mixing and molding a polyolefin polymer having a small tan δ and a ceramics dielectric powder having a large ε _r .

The polyolefin polymer used in the present invention is a polymer mainly composed of olefin hydrocarbons. That is, ethylene, propylene, 1-
It is a polymer consisting of a simple substance such as butene or 4-methylpentene, or a polymer mainly containing such a monomer. Such polymers include polyethylene, polypropylene, poly 1-butene, poly 4-methylpentene, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-
Examples thereof include acrylic acid copolymers, ethylene-ethyl acrylate copolymers, polyethylene ionomers, ethylene-vinyl acetate copolymer partial hydrolysates, and other ethylene-multi-component monomer (binary or higher) copolymers.
You may use such a polymer 1 type or in mixture of 2 or more types. The properties of such polymers are ε _r = 2.2-
It is 3.0 / 10 ⁶ Hz. On the other hand, tan δ <10 ^-2 / 10 ⁶
It is preferably in the range of Hz and is a thermoplastic resin.

The reason why such a polymer is used will be described with its features compared with other materials. First, since such a polymer is a thermoplastic resin,
Unlike thermosetting resins, it melts without a solvent and only by heating, so workability is excellent and workability is excellent, and the troublesome work of a curing reaction is unnecessary. Looking at the thermoplastic resin, it has low polarity, so it has excellent moisture resistance,
Even when such a polymer is mixed with another material, the wettability to the material to be mixed, and thus the kneading property is excellent.
Further, there are various advantages that deformation due to creep is less likely to occur even when compared with other low-polarity polymers such as rubber, and that the price is generally low compared to other so-called engineering plastics.

As a ceramic material for forming a dielectric powder mixed with a polyolefin-based polymer, 10 ⁶ to
Ε _r > 30, tan δ <1 × 10 in the frequency range of 10 ⁹ MHz
Materials showing a value of ^-2 are preferred. Examples of such ceramic materials include the following. LiO-SrO-NbO ₂ -TiO ₂ system {Example: SrTiO ₃ -Sr (Li
_{1 / 4Nb3 / 4) O 3} }, MgO-CaO-La 2 O 3 -TiO 2 system _{{Example: (MgCa) TiO 3 -La 2} Ti 2 O 7}, MgO-BaO-N
bO ₂ system {Example: Ba (Mg1 / 3Nb2 / 3) O ₃ }, MgO-SrO-N
bO ₂ system {example: Sr (Mg1 / 3Nb2 / 3) O ₃ }, CaO-TiO ₂ system {example: CaTiO ₃ }, CaO-SrO-TiO ₂ system {example: CaT
iO ₃ -SrTiO ₃ }, CaO-La ₂ O ₃ -TiO ₂ system {Example: Ca
TiO ₃ -La ₂ O ₃ -TiO ₂ }, CaO-Bi ₂ O ₃ -La ₂ O ₃ -Ti
O ₂ system {Example: CaTiO ₃ -La ₂ O ₃ -Bi ₂ O ₃ -TiO ₂ }, Mn
O ₂ -BaO-NbO ₂ system {Example: Ba (Mn1 / 3Nb2 / 3) O ₃ }, Z
nO ₂ -SrO-NbO ₂ system {Example: Sr (Zn1 / 3Nb2 / 3) O ₃ },
ZnO ₂ -BaO-NbO ₂ system {Example: Ba (Zn1 / 3Nb2 / 3)
O ₃ }, SrO-TiO ₂ system {Example: SrTiO ₃ }, SrO-Ba
O-La ₂ O ₃ -TiO ₂ system {Example: BaTiO ₃ -SrTiO ₃ -La ₂
O ₃ -TiO ₂ }, SrO-SnO ₂ system {Example: SrSnO ₃ }, Zr
O ₂ -TiO ₂ system {Example: ZrTiO ₄ }, ZrO ₂ -SnO ₂ -TiO
₂ system {Example: (ZrSn) TiO ₄ }, SnO ₂ -TiO ₂ system {Example: Sn
O ₂ -TiO ₂ }, BaO-TiO ₂ system {Example: Ba ₂ Ti ₉ O ₂₀ }, Ba
O-ZrO ₂ -TiO ₂ system {Example: Ba (ZrTi) O ₃ }, BaO-N
d ₂ O ₃ -TiO ₂ system {Example: BaTiO ₃ -Nd ₂ O ₃ -TiO ₂ }, B
_{aO-Nd 2 O 3 -PbO-} TiO 2 system {Example: BaO-PbO-Nd ₂ O
₃ -TiO ₂ }, BaO-Sm ₂ O ₃ -TiO ₂ system {Example: BaO-Sm ₂
O ₃ -TiO ₂ , BaO-Sm ₂ O ₃ -5TiO ₂ } BaO-Nd ₂ O ₃ -B
i ₂ O ₃ -TiO ₂ system, BaO-Nd ₂ O ₃ -Sm ₂ O ₃ -Bi ₂ O ₃ -Ti
O ₂ system, La ₂ O ₃ -TiO ₂ system {Example: La ₂ O ₃ -2TiO ₂ },
Nd ₂ O ₃ -TiO ₂ system {Example: Nd ₂ Ti ₂ O ₇ }, Bi ₂ O ₃ -TiO
₂ type {Example: Bi ₂ O ₃ -2TiO ₂ }, TiO ₂ Furthermore, such materials can be used alone or in admixture of two or more. The average particle diameter of the above-mentioned ceramic dielectric powder is preferably 100 μm or less, and particularly preferably 0.5 to 20 μm on average. If the average particle size is large, the surface becomes rough when formed into a substrate, and it is difficult to form a high-precision circuit. On the contrary, if the average particle size is small, the dielectric properties are deteriorated and the kneading workability with a polyolefin polymer is also deteriorated. Further, such a ceramic dielectric may be completely fired or incompletely fired, but is preferably completely fired. Further, the powder may be prepared by crushing after calcination, or may be prepared by a calcination method for adjusting the particle size.

The weight compounding ratio of the polyolefin-based polymer and the ceramics dielectric powder when forming the substrate is preferably 70:30 to 5:95. When the compounding amount of the ceramics dielectric powder is small, the dimensional stability as a substrate may be lacked or the dielectric properties may not be exhibited. On the other hand, if the amount is large, the moldability will deteriorate. Further, for the purpose of improving workability, various waxes such as amorphous polypropylene, polypropylene wax, polyethylene wax and other waxes having a smaller molecular weight than such polymers may be appropriately added to the polyolefin-based polymer. As a method for producing a substrate, for example, a method is used in which a ceramic dielectric powder is kneaded into a melted or softened polyolefin-based polymer little by little by using a heating two-roll, and then is kneaded into a plate shape using a spacer by a heating press. Is adopted. An extrusion kneader may be used for kneading. In addition, when creating a board, a metal deactivator (also called a copper damage inhibitor when the circuit is copper) to prevent deterioration of the polyolefin polymer due to the metal forming the circuit on the board is kneaded as necessary. You may mix at the time of. The blending amount of such a metal deactivator is 10
5 parts by weight or less with respect to 0 parts by weight. In order to improve the dispersibility of the ceramic dielectric powder during kneading,
A dispersant such as a titanate type or a silane coupling agent may be blended. The compounding amount of such a dispersant is 5 parts by weight or less with respect to 100 parts by weight of the ceramic dielectric powder.

Further, the method of forming a circuit on the surface of the substrate according to the present invention may be a subtractive method or an additive method, and a method of adhering a metal layer to be such a circuit to a substrate is electroless plating. Alternatively, electroless plating and electrolytic plating may be combined, and particularly in the case of a metal foil having good surface smoothness, a method of bonding with a high dielectric constant, low loss adhesive or the like may be used. Further, it is possible to form a surface circuit by a so-called transfer method in which a metal circuit pattern formed on another temporary substrate is pressure-bonded and transferred onto the main substrate by taking advantage of the fact that the main substrate is thermoplastic.

[0011]

The substrate of the present invention exhibits desired dielectric properties while maintaining the excellent dimensional accuracy and moldability of the mixture of polyolefin polymer and ceramic dielectric powder. Therefore, the substrate of the present invention can be manufactured in a small form with high accuracy.

[0012]

EXAMPLES Next, examples of the present invention will be described. In addition, all the compounding parts of a display show a weight part. Example 1 Commercially available polypropylene as a polyolefin-based polymer {MFR≈60, ε _r = 2.3, tan δ = 3 × 10 ⁻⁴ / 1
MHz, designated as (A)} 50 parts by weight were placed on a two-roll roll at 180 ° C. and melted, and sintered TiO ₂ as a ceramic dielectric powder {average particle size 1 μm, ε
_r = 100, tan δ = 3 × 10 ^-4 / 1 MHz, which is (B)
Kneading while adding 50 parts little by little, (A)
A mixture of + (B) was made. Furthermore, the mixture of (A) + (B) is put in a 5mm-thick frame that also serves as a spacer, sandwiched from both sides with two end plates, and press-molded at 210 ° C using a 50t press to give a 5mm-thickness. A substrate and a molded product of 10 × 10 × 10 mm were prepared.

Example 2 In the same manner as in Example 1, 20 parts of (A) and 80 parts of (B) were used to prepare a substrate and a molded article made of a mixture of (A) + (B).

Comparative Example 1 In the same manner as in Example 1, (A) was 2 parts and (B) was 98 parts.
An attempt was made to prepare a substrate composed of a mixture of (A) + (B), but it could not be molded.

Comparative Example 2 A substrate and a molded article made of a mixture of (A) + (B) with 80 parts of (A) and 20 parts of (B) were prepared in the same manner as in Example 1.

Comparative Example 3 In the same manner as in Example 1, 20 parts of (A) was melted and fired as a ceramic dielectric powder TiO ₂ {average particle size 0.3 μm, ε _r = 100, tan δ = 3. × 10 ^-4 / 1
The kneading was tried while adding 80 parts by mass of MHz, which is (B-2)}, but sufficient kneading was impossible.

Comparative Example 4 In the same manner as in Example 1, 50 parts of (A) was melted and fired as a ceramic dielectric powder TiO ₂ {average particle size 120 μm, ε _r = 100, tan δ = 3 × 10. ^-4 / 1
MHz, which is (B-3)}, was kneaded while adding 50 parts little by little to prepare a mixture of (A) + (B-3), and then a substrate and a molded product were prepared. However, after heating and returning to room temperature, the polymer part shrinks more than the ceramic dielectric powder, the surface becomes uneven and the roughness is conspicuous, and it is difficult to form a copper foil layer for measuring the characteristics of the substrate. The cutting process was extremely difficult.

Example 3 Polyethylene ionomer commercially available as a polyolefin polymer {Himilan 1652 manufactured by Mitsui DuPont Polychemical Co., ε _r = 2.4, tan δ = 1.0 × 10 ^-3 /
Using the same method as in Example 1, 20 MHz of 1 MHz, which is (C)}, and 80 parts of (B) as the ceramic dielectric powder are formed into a substrate made of a mixture of (C) + (B) and molded. I created a product.

Example 4 Commercially available poly-4-methylpentene as a polyolefin-based polymer {TPX manufactured by Mitsui Petrochemical Co., ε _r = 2.2, tan
δ = 5 × 10 ⁻³ / 1 MHz, which is (D)} 20
And 80 parts of (B) as the ceramic dielectric powder were processed in the same manner as in Example 1 to prepare a substrate and a molded product made of a mixture of (D) + (B).

Example 5 20 parts of (A) as a polyolefin polymer and commercially available BaO-Nd ₂ O ₃ -Bi ₂ O ₃ -as a ceramic dielectric powder.
TiO ₂ -based fired product {average particle size 5 μm, ε _r = 105, tan δ
= 3 × 10 ^-4 / 1 MHz, which is (E)} By using the same method as in Example 1 for 80 parts, a substrate and a molded product made of a mixture of (E) + (B) were prepared.

Based on the substrates and molded products prepared in Examples 1 to 5 above, ε _r at frequencies of 1 MHz and 800 MHz.
And tan δ were measured, test samples shown in FIGS. 1 and 2 were prepared. FIG. 1 shows a disk-shaped substrate 2 having a diameter of 56 mm and a thickness of 5 mm and a copper foil layer 1 formed on it. FIG. 2 shows a cylindrical substrate 3 having an outer diameter of 7 mm, an inner diameter of 3 mm and a height of 10 mm. Figure 1
Is a sample for measurement test at 1 MHz, and FIG. 2 is a sample for measurement test at 800 MHz. Moreover, the copper foil layer 1 in FIG.
Finished to a thickness of μm. Further, the measurement at 1 MHz was performed using an LCR meter manufactured by Yokogawa Hewlett-Packard (YHP), and the measurement at 800 MHz was performed using a vector network analyzer manufactured by YHP. The measurement results are shown in Table 1. The machinability was evaluated by the machinability during the preparation of the sample shown in FIG. In addition, Table 1 shows the measurement results of commercially available high frequency substrates for comparison. In Table 1, ∘ indicates that the moldability and workability are good, Δ indicates a little good, x indicates a defect, and ─ indicates that the measurement is not performed. This commercially available product is a cross-linked composite high frequency substrate whose main material is polyphenylene oxide. The embodiments of the present invention have been described above, but the present invention is not limited to these without departing from the gist of the present invention.

[0022]

[Table 1]

[0023]

Industrial Applicability The composite high dielectric constant substrate of the present invention has excellent dielectric properties because it is formed by mixing and molding a polyolefin polymer having a small tan δ and a ceramics dielectric powder having a large ε _r. Excel. Therefore, it can be applied to small information devices such as electronic devices and communication devices used in a high frequency region, and its social contribution is extremely large.

[Brief description of drawings]

FIG. 1 is a diagram showing a test sample for dielectric property measurement, (a)
Is a perspective view. (B) is a front sectional view.

FIG. 2 is a perspective view showing a test sample for dielectric property measurement.

[Explanation of symbols]

 1 ... Copper foil layer, 2 ... Substrate, 3 ... Substrate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tadamitsu Nakayama 2-1-1 Nishishinjuku, Shinjuku-ku, Tokyo Within Hitachi Chemical Co., Ltd. (72) Kenji Watanabe 1150 Goshomiya, Shimodate City, Ibaraki Prefecture Hitachika Seigo Co., Ltd. Goshomiya Plant (72) Inventor Kozaburo Nakamura 1-1-6 Uchiyuki-cho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation (72) Inventor Mikio Takeshima 1-1-1 Uchisai-cho, Chiyoda-ku, Tokyo No. 6 Nihon Telegraph and Telephone Corporation (72) Inventor Fumio Yamamoto 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (1)

[Claims] 1. A composite high dielectric constant substrate obtained by mixing and molding a polyolefin polymer and a ceramics dielectric powder.