Resin composition to be plated

Abstract: A resin composition for plating comprising a thermoplastic resin and aluminum borate or amorphous silica, or both as an inorganic filler. The resin composition exhibits excellent plating characteristics and excellent electrical characteristics.

Description: BACKGROUND OF THE INVENTION Field of the Invention: The present invention relates to a resin composition which can be plated. The resin composition has superior plating characteristics and excellent electrical characteristics, and is particularly useful as a material for electric or electronic parts such as printed circuit boards, wiring circuit boards, connectors, housing, and insulators. More particularly, because the resin composition of the present invention is thermoplastic and has excellent plating and electrical characteristics, it is suitable as a material for manufacturing three dimensional circuit boards, molded interconnection devices (MID), and molded circuit boards (MCB) using injection molding techniques. Discussion of the Background: Because thermoplastic resin compositions having superior plating characteristics can be easily processed by injection molding or extrusion molding into three dimensional articles, such compositions are abundantly used for various electric or electronic parts, automobile parts, mechanical parts, and ornamental articles. Conventional resin compositions capable of being plated exhibit adequate plating characteristics due to improvements in the shape and size of fillers which are added to such compositions and development in the plating technology. In addition to the excellent plating characteristics thermoplastic resins used for electronic parts, such as printed circuit boards, wiring circuit boards, connectors, housing, and insulators, must have excellent electrical characteristics. Here, the plating characteristics indicate the capability of connecting the plated resin composition and the plating metal, that is, the adhesion between the resin composition and the metal plating film. Excellent resin-metal adhesion means excellent plating characteristics. Excellent electrical characteristics, on the other hand, are characteristics required for an insulating resin material, particularly a high frequency insulating resin material. Specifically, a material having excellent electrical characteristics must have a low dielectric constant (ε) and a low dielectric loss tangent (tan δ). However, conventional resins and resin compositions to be plated have a high dielectric constant and a high dielectric loss tangent. For example, resins to be plated disclosed in Japanese Patent Application Laid-open Nos. 136841/1981, 230276/1993, and 98637/1989 have excellent plating characteristics and possess an extremely high value industrially. However, because of their poor electrical characteristics, application of these resins must be limited. For example, it is difficult to use these resins for electronic parts used in the high frequency wave region due to a large signal loss. On the other hand, the adhesion strength between a molded resin and a metal plating film is largely affected by the physical characteristics of the resin surface, that is, roughness of the resin surface. In particular, the plating adhesion strength is remarkably improved by forming uniformly small anchoring pores (hereinafter called "micropores"). This is called the anchoring effect. In many cases, a chemical etching process using an acid, an alkali, or an organic solvent is used for forming micropores on the surface of molded resins. Such micropores can be easily formed by a chemical etching process which comprises, for example, manufacturing molded articles from a resin composition comprising a prescribed amount of inorganic filler which is soluble in an acid, an alkali, or an organic solvent and immersing the molded resin surface in a specific solvent (the acid, alkali, or organic solvent) to cause the inorganic filler to dissolve out and be removed. In this manner a resin composition comprising a thermoplastic resin and a specific inorganic filler which is soluble in an acid, an alkali, or an organic solvent has been conventionally used as the resin composition to be plated. Various fillers, such as calcium carbonate, glass, magnesium carbonate, magnesium oxide, calcium pyrophosphate, barium sulfate, barium carbonate, and zinc oxide, are used as the inorganic filler. These conventional inorganic fillers, however, impair the electrical characteristics of the resins, for example, by increasing the dielectric constant or the dielectric loss tangent. The increase in the dielectric constant or the dielectric loss tangent causes the signal loss to increase or delays the signal transmission speed, particularly when the product is used as an insulating material for electronic parts, inter alia, electronic parts for high frequency wave signals. Here, the high frequency signals are signals of a frequency in the range of 1 GHz or larger. Specific equipment using high frequency signals includes cellular phones, PHS, pocket bells, satellite terminals, navigation systems, wireless LANs, and the like. Conventionally, there has been no report disclosing resin compositions having both excellent plating characteristics and excellent electrical characteristics (low dielectric constant and low dielectric loss tangent). Because of miniaturization and high integration of electronic parts in recent years, great attention is given to the technologies for manufacturing electrohic parts by injection molding which is suitable for molding small and integrated parts. An object of the present invention is therefore to provide a thermoplastic resin composition for plating, suitable for injection molding and having both excellent plating characteristics and excellent electrical characteristics. In view of this situation the present inventors have conducted extensive studies and found that the addition of a specific inorganic filler to a thermoplastic resin produces a resin composition exhibiting both excellent plating characteristics and excellent electrical characteristics. SUMMARY OF THE INVENTION Accordingly, a specific object of the present invention is to provide a resin composition exhibiting both excellent plating characteristics and excellent electrical characteristics comprising a thermoplastic resin and amorphous silica of the chemical formula SiO 2 which has an average particle diameter of 0.01 to 100 µm and an aspect ratio of 10 or less. Other objects, features and advantages of the invention will hereinafter become more readily apparent from the following description. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Amorphous silica used in the present invention has aspect ratios of 10 or smaller, preferably 5 or smaller, and an average particle diameter of 0.01-100 µm. The resin composition of the present invention preferably has a dielectric constant of 4.0 or smaller and a dielectric loss tangent of 0.01 or smaller in the high frequency region of 100 KHz to 300 GHz. Resins represented by commercially available thermoplastic resins are used as the thermoplastic resins of the present invention. Specific examples of such thermoplastic resins include general purpose resins, such as polyethylene (PE), polypropylene (PP), polystyrene (PS), polymethyl methacrylate (PMMA), ABS resin, and AS resins; engineering plastics, such as polyacetate (POM), polycarbonate (PC), polyphenylene ether (PPE), polyamide (PA: nylon), polyethylene terephthalate (PET), and polybutylene terephthalate (PBT); and other thermoplastic resins such as polyphenylene sulfide (PPS), polyether sulfone (PES), polyether imide (PEI), polyether ether ketone (PEEK), polyketone (PK), polyimide (PI), polycyclohexanedimethanol terephthalate (PCT), polyallylate (PAR), and various liquid crystal polymers (LCP). These resins may be used individually or may be used as a polymer alloy or a polymer blend which is a multicomponent polymer system consisting of two or more of these resins chemically or physically blended in prescribed proportions. A denatured product of these resins can also be used. The denatured product here means a synthetic resin or a mixture of synthetic resins, of which a part of the basic component is replaced by another component when the resins are reacted or compounded. Given as preferred combinations of resins in multicomponent polymer systems are, as binary systems, PPE/PS, PPE/PC, PPE/PA, PPE/PET, PPE/PBT, PPE/PEI, PPE/PPS, PPE/PES, PPE/PEEK, PPE/PCT, PPE/LCP, PEI/PC, PEI/PEEK, PEI/LCP, PEI/PET, PEI/PBT, LCP/PAR, LCP/PEEK, LCP/PET, LCP/PBT, LCP/PC, LCP/PCT, and LCP/PEEK, and as ternary systems, PPE/PC/PS, PPE/PEI/PC, PPE/PEI/PS, PEI/PPE/LCP, PEI/PC/LCP, PEI/PEEK/LCP, and the like. A compatibilizer or the like may be added to these polymer alloys or polymer blends to improve compatibility among the polymers. Given as examples of specific compatibilizers which can be used are copolymers of epoxy-modified-MMA and MMA; copolymers of epoxy-modified-St and St; copolymers of epoxy-modified-St and MMA; copolymers of epoxy-modified-MMA and St; copolymers of St and maleic anhydride; copolymers of St and MMA; and copolymers of maleic anhydride and vinyl compound. These copolymers may be random copolymers, block copolymers, alternating copolymers, or graft copolymers. The thermoplastic resin used in the present invention may contain various additives which may improve the basic characteristics of the resins, such as mechanical characteristics, electrical characteristics, heat resistance, molding processability, fluidity, flame retarding characteristics, UV resistance, chemical resistance, and outward appearance of the molded products, and to provide a color or glossiness to the products. Plasticizers, thermal stabilizers, oxidation stabilizers, cross-linking agents, flame retardants, UV absorbers, coloring agents, glossing agents, and the like are given as examples of specific additives. The inorganic filler used in the present invention which is amorphous silica is shown by the following formula: SiO 2 The amorphous silica is preferably that containing 96% or more, preferably 99% or more, of silicon oxide (SiO 2 ). Such an amorphous silica is manufactured, for example, by melting quartz (crystalline silica) and cooling the molten silica. The dielectric constant and dielectric loss tangent are high if the amount of silicone oxide in the amorphous silica is less than 96%. The amorphous silica used in the present invention is a powdery or globular filler having an aspect ratio, which is the ratio of the length along the long axis to the length along the short axis, of 10 or less, preferably 5 or less, and an average diameter of 0.01-100 µm, preferably 0.1-50 µm. The closer the aspect ratio to 1, that is, the closer the shape of the filler to a sphere, the greater the degree of improvement in the plating characteristics. If the aspect ratio is too large, specifically larger than 10, the shape of the micropores is fibrous, remarkably decreasing the plate adhesion strength. If the average particle diameter is less than 0.01 µm, it is difficult for the catalysts for non-electrolytic plating to adhere to the surface of the molded product. This results not only in insufficient adhesion strength, but also uneven plating. If the average particle diameter is larger than 100 µm, the micropores are too large to provide sufficient anchoring. As a result, only weak physical bonding is obtained between the plated film and the resin. The amount of the inorganic filler, that is, amorphous silica, is 5-70 parts by weight, preferably 10-60 parts by weight, for 100 parts by weight of the total amount of the thermoplastic resin and the inorganic filler. If the amount of the inorganic filler is less than 5 parts by weight, sufficient plating adhesion strength cannot be obtained; if larger than 70 parts by weight, the fluidity of the resulting resin composition is remarkably lowered and molding processability is impaired. In order to improve dispersibility and affinity to the resin, thermal stability and oxidation stability, the inorganic fillers used in the present invention may be surface-treated by a conventional method. The addition of a coupling agent is given as an example of the method of surface treatment. Given as examples of coupling agents which can be preferably used are silane coupling agents, such as vinyltrichlorosilane, vinyltris(β-methoxyethoxy)silane, vinyltriethoxysilane, vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, di(3-triethoxysilylpropyl)tetrasulfide, 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2(aminoethyl)-3-aminopropyltrimethoxysilane, vinyltri(2-methoxyethoxy)silane, 3-methacryloyloxypropyltrimethoxysilane, and 3-glycidyloxypropyltrimethoxysilane; and titanate coupling agents, such as triisostearoylisopropyl titanate, di(dioctylphosphate)diisopropyl titanate, didodecylbenzenesulfonyldiisopropyl titanate, and diisostearyldiisopropyl titanate. These coupling agents can be used in an amount which does not impair the electrical characteristics or plating characteristics, usually in an amount of 0.0001-1 part by weight for 100 parts by weight of the inorganic filler. Further, it is possible to use inorganic fillers other than amorphous silica to an extent which does not impair the electrical characteristics and plating characteristics. Given as examples of such other inorganic fillers which can be used together are glass, glass single fiber, glass fiber, glass balloons, shirasu balloons, chopped strands, carbon fiber, carbon, carbon black, alamide, potassiumtatanate, magnesium borate, calcium carbonate, magnesium carbonate, magnesium sulfate, calcium sulfate, aluminum sulfate, pyrophosphate, silicon nitride, aluminum nitride, boron nitride, silicon carbide, alumina, alumina fiber, silica, mica, talc, diatomaceous earth, clay, volcanic ash, lime stone, bentonite, titanium oxide, magnesium oxide, calcium oxide, molybdenum disulfide, and the like. The resin composition of the present invention can be manufactured by a conventional process for manufacturing common composite materials. Industrially, a melt-kneading method is preferred in view of productivity and economy. Specific examples of such methods include a kneading method using a biaxial or uniaxial extruder, and a method using a batch-type heating melt-kneader which is typified by the laboplast mill. Because the resin composition of the present invention is thermoplastic, injection molding or extrusion molding can be used for manufacturing molded products from the resin composition. Films or membranes can also be manufactured by a solvent cast method using an organic solvent or the like. In the same way as in the case of conventional resin compositions for plating, the strength of adhesion between the molded products made from the resin composition of the present invention and the plating metal film (the plating adhesion strength) depends on the physical characteristics of the molded surface of the resin composition, specifically the roughness of the molded resin surface. It is possible to remarkably improve the plating adhesion strength from the anchoring effect obtained by forming uniform micropores of an appropriate size on the surface of the molded article before plating. In the same manner as in the case of molded products made from conventional resin compositions for plating, chemical etching is effective for producing the micropores. As mentioned above, the chemical etching can be carried out by immersing the molded resin surface in an acid, alkali, or organic solvent, or the like and dissolving and removing the inorganic filler from the surface of the molded article. Because amorphous silica used in the present invention is soluble in alkaline aqueous solutions, it is possible to dissolve amorphous silica and remove these from the surface of molded articles by chemically etching that surface with an alkaline aqueous solution, thereby producing micropores which are effective for plating. As the alkaline aqueous solution, aqueous solutions of sodium hydroxide, potassium hydroxide, lithium hydroxide, and the like are preferred in view of the solubility of aluminum borate and amorphous silica, and also in view of economy. These alkaline aqueous solution may be used either individually or mixed. The preferred concentration of the alkaline aqueous solution is in the range of 1 N to 15 N, and particularly in the range of 3 N to 12 N. If the alkali concentration is too small, it takes a long time for the amorphous silica to dissolve out; if the concentration is too high, the resin may exhibit conspicuous deterioration, resulting in a decrease in the plating adhesion strength. In the case where inorganic fillers other than amorphous silica are used, these other inorganic fillers may be chemically etched together with amorphous silica. In this case, the etching solution is selected taking into consideration the characteristics (e.g., the solubility, corrosivity, etc.) of such other inorganic fillers. For instance, when calcium carbonate, pyrophosphate, or barium sulfate is used together with amorphous silica, an acid, such as sulfuric acid, hydrochloric acid, chromic acid, phosphoric acid, acetic acid, or boric acid, a mixture of two or more of these acids, or aqueous solution of one or more of these acid can be used. When glass-type or alumina-type fillers are used together, an alkali, such as an aqeous solution of potassium hydroxide, sodium hydroxide, or lithium hydroxide, or mixture of these, at any optional concentration, can be used. In any of the above cases, the chemical etching is carried out at room temperature (20°C) to 120°C, preferably at a temperature of 50°C to 100°C. If the etching temperature is too low, it takes a long time for the inorganic fillers to dissolve out; if too high, deterioration of the resin is conspicuous. To improve the rate of dissolution of the organic fillers it is possible to agitate the mixture, irradiate the mixture with ultrasonic waves, or bubble air through the mixture, during the chemical etching. In addition, to carry out the chemical etching more effectively a procedure called pre-etching, which consists of exposing the inorganic fillers by dissolving the resin on the surface of molded article (a skin layer of resin), may be applied. Conventional methods of pre-etching can be used. Among organic solvents, alkaline solutions, and acids commonly used for pre-etching, organic solvents or acids are particularly preferred in the present invention. Preferred organic solvents used for pre-etching are, for example, chloroform, dichloromethane, benzene, toluene, xylene, pyridine, hexane, tetrahydrofuran, acetonitrile, ethyl acetate, N,N-dimethylformamide, N-methylpyrrolidone, and dimethylsulfoxide. Sulfuric acid, hydrochloric acid, chromic acid, nitric acid, or phosphoric acid, or mixtures of these are given as preferred examples of the acids. Except for the chemical etching step and the pre-etching step, the molded products produced from the resin composition of the present invention may be plated by non-electrolyte plating or electrolytic plating in the same manner as in conventional resin compositions for plating. As previously mentioned, the resin composition of the present invention preferably has a dielectric constant of 4.0 or less and a dielectric loss tangent of 0.01 or less in the high frequency region of 100 KHz to 300 GHz. Resin compositions having a dielectric constant greater than 4.0 or a dielectric loss tangent greater than 0.01 in the above frequency region may unduly increase signal loss when used as an insulating material for electronic parts, particularly the electronic parts or materials used in a high frequency region of 1 GHz or greater, making it difficult to reasonably design circuits and the like. Such parts or materials are unusable in some on applications. Other features of the invention will become apparent in the course of the following description of the exemplary embodiments. EXAMPLES Amorphous silica used in the examples and comparative examples was made by melting quartz (crystalline silica) with an SiO 2 purity of 99.9% or more, and cooling the molten silica. The following resins were used in the examples and comparative examples. PEI: Polyether imide, Ultem 1000™, manufacturedbyGE Plastics Japan Ltd. PPE: Denatured polyphenylene ether, XYRON PXL X9102™, manufactured by Asahi Chemical Industry Co., Ltd. LCP: Liquid crystal polymer, SUMIKASUPER LCP E6000™, manufactured by Sumitomo Chemical Co., Ltd. PA: Nylon 6, NOVAMID 1013C™, manufactured by Mitsubishi Chemical Corp. POM: Polyacetate, Tenac 3010™, manufactured by Asahi Chemical Industry Co., Ltd. PBT: Polybutylene terephthalate, Teijin PBT CN-7000™, manufactured by Teijin Co. PEEK: Polyether ether ketone, VICTREX 45G™, manufactured by Sumitomo Chemical Co., Ltd. PPS: Polyphenylene sulfide, Lightone R-4™, manufactured by Dainippon ink and chemicals, Inc. PC: Polycarbonate, NOVAREX 7022A™, manufactured by Mitsubishi Chemical Corp. Example 1-32 <Preparation of resin compositions to be plated> Thermoplastics, and amorphous silica were pre-blended in the proportions shown in Tables 1-1 to 1-2. The mixture was fed into a biaxial extruder (ZE40A™, manufactured by Hermann Berstorff Maschinenban GmbH) using a quantitative feeder at a rate of 20-60 kg/hour, and melt-kneaded at the temperatures and rotations shown in Tables 2-1 to 2-2. After cooling, the strands were cut by a pelletizer to produce pellets. <Molding> The pellets were dried at 100-150°C in a thermostat and molded by an injection molding machine (F-85™, manufactured by Klockner Ferromatik Desma GmbH) at the molding temperatures shown in Tables 2-1 to 2-2 to prepare test leaves for the evaluation of plating characteristics and electrical characteristics. The shapes of the test leaves were as follows. <Shapes of test leaves> ASTM #1 Dumbbell: for the evaluation of plating characteristics Disc 1,  100 mm x 1.6 mm: for the evaluation of electrical characteristics in the frequency range of 1-15 MHz Disc 2,  100 mm x 0.8 mm: for the evaluation of electrical characteristics in the frequency range of 1-25 GHz <Plating> The above test leaves were de-fatted by treating with Ace Clean A220™ manufactured by Okuno Chemical Industries Co., Ltd. at 60°C for 5 minutes and washed with water. The flat surface of the test leaves was chemically etched under the conditions shown in Tables 3-1 to 3-2 or Table 8. After chemical etching, the test leaves were neutralized with 5 g/l NaOH aqueous solution or 5 ml/l HCl aqueous solution at 25°C for 3 minutes followed by washing with water, conditioned with 150 ml/l of Condilizer SP™ manufactured by Okuno Chemical Industries Co., Ltd. at 50°C for 4 minutes followed by washing with water. The test leaves were then catalyzed with 60 ml/l of Catalyst C™ manufactured by Okuno Chemical Industries Co., Ltd. and 150 ml/l HCl at room temperature for 4 minutes, followed by washing with water, and activated with 5 wt% HCl acqueous solution at 25°C for two minutes. After washing with diluted H 2 SO 4 , the test leaves were non-electrolytically plated in OPC-750™ manufactured by Okuno Chemical Industries Co., Ltd. using 100 ml/l of A solution, 100 ml/l of B solution, and 2ml/l of C solution, followed, after washing with diluted H 2 SO 4 , by electroplating (copper plate, thickness: 40 µm) in a copper sulfate bath (120-250 g/l of CuSO 4 · 5H 2 O; 30-100 g/l of H 2 SO 4 ; 20-80 mg/l of Cl - ion) under the conditions of the electric current density of 1-20 A/dm 2 , the bath voltage of 1-5 V and the source voltage of 6-8 V. <Evaluation of plating characteristics> Evaluation of surface conditions after chemical etching The test leaves (ASTM #1 Dumbbell) were dried after chemical etching . A cellophane tape (width: 18 mm, manufactured by Nichiban Co., Ltd.) was attached to the chemically etched surface and pressed (pressure: about 500 g) to attach the tape to the surface of the test leaf. The tape was then peeled off uninterruptedly at an angle of 90° to evaluate the peelability of the surface layer by macroscopic observation. The results are classified as follows: o ○ There was no release of resin from the surface whatsoever. ○ There was almost no release of resin from the surface. Δ Part of the surface resin was released. × The resin surface was attached to the tape and released with the tape. ·Evaluation of external appearance of plated surface After electroplating, the external appearance of the plated surface (uniformity of plated film, presence or absence of plating swelling) was macroscopically observed according to the following criteria. (Uniformity of plated film) o ○ The surface was uniform and mirror-like ○ The surface was uniform and almost mirror-like. Δ Part of the surface was not uniform. × The surface was not uniform as a whole. (Swelling of plated film) o ○ There was no swelling of the plated film whatsoever. ○ There was almost no swelling of the plated film. Δ Part of the plated film exhibited swelling. × Complete swelling of the plated film was observed. ·Measurement of plate film adhesion strength After electroplating, a stripe 1 cm in width was cut out with a cutter knife. The tip of the stripe was pulled upward at 90° and this tip was attached to a spring to measure the strength required to release the plated film (kg/cm). <Evaluation of electrical characteristics> ·Measurement of dielectric constant and dielectric loss tangent Measured wave length: 1 MHz, 10 MHz, 1GHz, 10GHz, 20 GHz Measurement temperature: 25°C Measuring method: (1) Parallel plate electrode method (1-15 MHz) (2) Triplate line resonator method (Loss separation method; 1-25 GHz) The results of evaluation of peelability of the surface layer and plating characteristics after chemical etching are shown in Tables 3-1 to 3-2. The results of evaluation of the electrical characteristics are shown in Tables 4-1 to 4-2. Example No. Resin Inorganic Filler (Amorphous silica) Types Amount (wt%) Amount (wt%) Average Diameter (µm) Aspect Ratio (Average) 1 PEI 80 20 5.2 1.4 2 PEI 70 30 5.2 1.4 3 PEI 60 40 5.2 1.4 4 PEI 40 60 5.2 1.4 5 PEI 60 40 3.1 1.5 6 PEI 60 40 1.2 1.3 7 PEI 60 40 7.9 1.4 8 PEI 60 40 27.0 1.3 9 PEI 60 40 3.1 3.0 10 PEI 60 40 3.1 7.8 11 PPE 60 40 5.2 1.4 12 POM 60 40 5.2 1.4 13 PA 60 40 5.2 1.4 14 PBT 60 40 5.2 1.4 15 PEEK 60 40 5.2 1.4 16 PPS 60 40 5.2 1.4 17 LCP 60 40 5.2 1.4 18 PPE 60 40 0.1 1.6 19 PPE 60 40 50 1.2 20 PPE 30 70 5.2 1.4 21 PPE 90 10 5.2 1.4 22 PPE 95 5 5.2 1.4 Example No. Resin Inorganic Filler (Amorphous silica) Types Amount (wt%) Amount (wt%) Average Diameter (µm) Aspect Ratio (Average) 23 PEI/PPE 25/25 50 5.2 1.4 24 PEI/PPE 30/20 50 5.2 1.4 25 PEI/PPE 20/30 50 5.2 1.4 26 PEI/PPE/LCP 20/20/10 50 5.2 1.4 27 PPE/PA 25/25 50 5.2 1.4 28 PPE/PC 25/25 50 5.2 1.4 29 PEI/PC 30/20 50 5.2 1.4 30 PEI/PPE 18/42 40 5.2 1.4 31 PEI/PPE 18/42 40 5.2 1.4 32 PEI/PPE 18/42 40 5.2 1.4 Example No. Kneading Conditions Temperature Rotation Injection Nozzle Temperature (°C) rpm (°C) 1 300 150 310 2 300 150 310 3 300 150 320 4 300 150 340 5 300 150 320 6 300 150 320 7 300 150 320 8 300 150 320 9 300 150 320 10 300 150 320 11 260 150 290 12 210 150 220 13 250 150 260 14 240 150 260 15 350 150 390 16 320 150 340 17 340 150 340 18 260 140 290 19 260 150 290 20 270 100 300 21 260 150 290 22 260 150 290 Example No. Kneading Conditions Temperature Rotation Injection Nozzle Temperature (°C) rpm (°C) 23 300 150 320 24 300 150 320 25 300 150 320 26 300 150 330 27 280 150 300 28 250 150 260 29 280 150 300 30 300 150 320 31 300 150 320 32 300 150 320 Example No. Chemical Etching Conditions Surface Evaluation of plated film Soln. Conc. Temp. (°C) Time (min) Peelability Appearance Adhesion Uniformity Swelling (Kg/cm) 1 Acq.KOH 8N 90 60 o ○ o ○ o ○ 1.36 2 Acq.KOH 8N 90 90 o ○ o ○ o ○ 1.49 3 Acq.KOH 8N 90 90 o ○ o ○ o ○ 1.88 4 Acq.KOH 8N 90 90 o ○ o ○ o ○ 1.95 5 Acq.KOH 8N 90 90 o ○ o ○ o ○ 1.51 6 Acq.KOH 8N 90 90 o ○ o ○ o ○ 1.47 7 Acq.KOH 8N 90 90 o ○ o ○ o ○ 1.48 8 Acq.KOH 8N 90 90 o ○ o ○ o ○ 1.35 9 Acq.KOH 8N 90 90 o ○ o ○ o ○ 1.45 10 Acq.KOH 8N 90 120 o ○ o ○ o ○ 1.41 11 Acq.KOH 8N 90 60 o ○ o ○ o ○ 1.56 12 Acq.KOH 8N 90 90 o ○ o ○ o ○ 1.52 13 Acq.KOH 8N 90 90 o ○ o ○ o ○ 1.47 14 Acq.KOH 8N 90 90 o ○ o ○ o ○ 1.48 15 Acq.KOH 8N 90 90 o ○ o ○ o ○ 1.72 16 Acq.KOH 8N 90 90 o ○ o ○ o ○ 1.31 17 Acq.KOH 8N 90 90 o ○ o ○ o ○ 1.57 18 Acq.KOH 8N 90 90 o ○ o ○ o ○ 1.21 19 Acq.KOH 8N 90 90 o ○ o ○ o ○ 1.78 20 Acq.KOH 8N 90 90 o ○ o ○ o ○ 1.23 21 Acq.KOH 8N 90 90 o ○ o ○ o ○ 1.10 22 Acq.KOH 8N 90 90 ○ ○ ○ 1.02 Example No. Chemical Etching Conditions Surface Evaluation of plated film Soln. Conc. Temp. (°C) Time (min) Peelability Appearance Adhesion Uniformity Swelling (Kg/cm) 23 Acq.KOH 8N 90 90 o ○ o ○ o ○ 1.71 24 Acq.KOH 8N 90 90 o ○ o ○ o ○ 1.63 25 Acq.KOH 8N 90 90 o ○ o ○ o ○ 1.69 26 Acq.KOH 8N 90 90 o ○ o ○ o ○ 1.53 27 Acq.KOH 8N 90 90 o ○ o ○ o ○ 1.41 28 Acq.KOH 8N 90 90 o ○ o ○ o ○ 1.54 29 Acq.KOH 8N 90 90 o ○ o ○ o ○ 1.63 30 Acq.KOH 8N 90 90 o ○ o ○ o ○ 1.63 31 Acq.KOH 8N 90 90 o ○ o ○ o ○ 1.65 32 Acq.KOH 8N 90 90 o ○ o ○ o ○ 1.42 (Upper row: Dielectric constant Lower row: Dielectric loss tangent) Example No. 1 MHz 10 MHz 1 GHz 10 GHz 20 GHz 1 3.15 3.14 3.10 3.10 3.10 0.003 0.004 0.005 0.005 0.006 2 3.19 3.18 3.12 3.12 3.11 0.003 0.004 0.005 0.006 0.006 3 3.20 3.19 3.15 3.14 3.13 0.004 0.004 0.005 0.005 0.006 4 3.25 3.24 3.24 3.22 3.20 0.003 0.003 0.004 0.005 0.005 5 3.21 3.20 3.17 3.15 3.13 0.003 0.004 0.004 0.005 0.005 6 3.20 3.20 3.15 3.15 3.14 0.003 0.003 0.004 0.005 0.006 7 3.20 3.19 3.18 3.14 3.14 0.003 0.004 0.005 0.005 0.006 8 3.21 3.20 3.17 3.15 3.15 0.004 0.004 0.005 0.006 0.006 9 3.20 3.20 3.19 3.16 3.13 0.003 0.004 0.005 0.006 0.007 10 3.21 3.19 3.17 3.16 3.15 0.003 0.004 0.004 0.005 0.006 11 2.92 2.90 2.89 2.88 2.86 0.001 0.001 0.002 0.002 0.002 12 3.62 3.61 3.60 3.58 3.56 0.005 0.005 0.006 0.006 0.007 13 3.34 3.34 3.32 3.31 3.30 0.007 0.008 0.008 0.009 0.009 14 3.21 3.19 3.18 3.17 3.17 0.001 0.001 0.001 0.001 0.001 15 3.08 3.06 3.04 3.02 3.01 0.002 0.002 0.003 0.003 0.003 16 3.49 3.48 3.46 3.45 3.44 0.004 0.004 0.005 0.005 0.005 17 3.59 3.58 3.58 3.58 3.58 0.007 0.007 0.007 0.005 0.004 18 2.88 2.87 2.86 2.86 2.85 0.001 0.001 0.001 0.001 0.001 19 2.89 2.89 2.87 2.85 2.84 0.001 0.001 0.002 0.002 0.002 20 2.98 2.97 2.95 2.94 2.93 0.002 0.002 0.003 0.003 0.003 21 2.68 2.67 2.65 2.64 2.64 0.002 0.001 0.002 0.002 0.002 22 2.65 2.64 2.62 2.61 2.60 0.002 0.002 0.002 0.002 0.003 (Upper row: Dielectric constant Lower row: Dielectric loss tangent) Example No. 1 MHz 10 MHz 1 GHz 10 GHz 20 GHz 23 3.01 3.00 2.97 2.96 2.95 0.003 0.003 0.003 0.003 0.003 24 3.02 3.01 2.99 2.99 2.98 0.003 0.004 0.004 0.004 0.004 25 2.98 2.97 2.95 2.94 2.93 0.003 0.003 0.003 0.004 0.004 26 2.99 2.98 2.97 2.96 2.96 0.004 0.005 0.005 0.005 0.006 27 2.98 2.97 2.95 2.95 2.94 0.005 0.006 0.007 0.007 0.007 28 2.82 2.81 2.79 2.78 2.77 0.003 0.003 0.003 0.004 0.005 29 2.99 2.98 2.97 2.96 2.96 0.003 0.003 0.004 0.004 0.005 30 2.79 2.78 2.76 2.76 2.75 0.002 0.002 0.002 0.002 0.002 31 2.85 2.84 2.85 2.83 2.83 0.002 0.002 0.002 0.003 0.003 32 2.85 2.84 2.82 2.81 2.79 0.001 0.001 0.002 0.002 0.002 Comparative Examples 1-14 <Preparation of Resin Compositions to be Plated> Thermoplastic resins and inorganic fillers were pre-blended in the proportions shown in Table 5. The mixtures were fed into a biaxial extruder (ZE40A™, manufactured by Hermann Berstorff Maschinenban GmbH) using a quantitative feeder at a rate of 40-60 kg/hour, and melt-kneaded at the temperatures and rotations shown in Table 6. After cooling with water, the strands were cut by a pelletizer to produce pellets. <Molding> The pellets were molded in the same manner as in Examples 1-33 except for those items listed in Table 6, thereby preparing test leaves for the evaluation of plating characteristics and electrical characteristics. <Plating, Evaluation of Plating Characteristics, and Evaluation of Electrical Characteristics> The same procedures as in Examples 1-33 were followed in principle, except that for the chemical etching conventional solvents were used under the conventionally reported conditions (temperatures and reaction time) shown in Table 7. The results of evaluation of surface layer peelability and plating characteristics after chemical etching are shown together in Table 7 and the results of evaluation of electrical characteristics are shown in Table 8. Comparative Example No. Resin Inorganic Filler Types Amount (wt%) Amount (wt%) Average Diameter (µm) Aspect Ratio (Average) 1 PEI 50 Glass fiber 50 - 80 2 PEI 50 Calcium pyrophosphate 50 10 1.2 3 PEI 50 Calcium carbonate 50 8 1.3 4 PEI 50 Barium sulfate 50 5 1.4 5 PEI 50 Glass beads 50 10 1.1 6 PEI 50 Aluminum oxide 50 15 1.3 7 LCP 50 Calcium pyrophosphate 50 10 1.2 8 PPE 50 Calcium carbonate 50 8 1.3 9 PPE 50 Calcium pyrophosphate 50 10 1.2 10 PA 50 Calcium pyrophosphate 50 10 1.2 11 PEI/PPE 25/25 Calcium pyrophosphate 50 10 1.2 12 PEI/PPE 30/20 Calcium pyrophosphate 50 10 1.2 13 PEI/PPE/LCP 20/20/10 Calcium pyrophosphate 50 10 1.2 14 PA/PPE 25/25 Calcium pyrophosphate 50 10 1.2 Comparative Example No. Kneading Conditions Injection Nozzle Temperature Temperature Rotation (°C) rpm (°C) 1 320 100 340 2 320 100 340 3 320 100 340 4 320 100 340 5 320 100 330 6 320 100 340 7 330 100 340 8 290 150 300 9 290 150 300 10 250 150 250 11 300 100 330 12 300 100 330 13 310 100 330 14 290 100 300 Comp. Example No. Chemical Etching Conditions Surface Evaluation of plated film Soln. Conc. Temp. (°C) Time (min) Peelability Appearance Adhesion Uniformity Swelling (Kg/cm) 1 Acq.NaOH 10N 80 120 × × × 0.23 2 Conc.H 2 SO 4 25 15 o ○ o ○ o ○ 1.85 3 Conc.H 2 SO 4 25 15 ○ ○ ○ 1.46 4 Conc.H 2 SO 4 25 15 ○ ○ ○ 1.50 5 Acq.NaOH 10N 80 120 ▵ ○ ○ 1.30 6 Acq.NaOH 10N 80 120 ○ ○ ○ 1.19 7 Conc.H 2 SO 4 25 15 o ○ o ○ o ○ 1.86 8 Conc.H 2 SO 4 25 15 ▵ ○ ○ 1.10 9 Conc.H 2 SO 4 25 15 o ○ ○ ○ 1.26 10 Conc.H 2 SO 4 25 15 o ○ o ○ o ○ 1.36 11 Conc.H 2 SO 4 25 15 o ○ o ○ o ○ 1.45 12 Conc.H 2 SO 4 25 15 o ○ o ○ o ○ 1.65 13 Conc.H 2 SO 4 25 15 o ○ o ○ o ○ 1.80 14 Conc.H 2 SO 4 25 15 o ○ o ○ o ○ 1.47 (Upper row: Dielectric constant Lower row: Dielectric loss tangent) Comparative Example No. 1 MHz 10 MHz 1 GHz 10 GHz 20 GHz 1 4.51 4.44 4.41 4.40 4.28 0.032 0.033 0.035 0.039 0.042 2 4.48 4.42 4.36 4.35 4.35 0.028 0.028 0.029 0.030 0.033 3 3.99 3.97 3.96 3.96 3.95 0.015 0.015 0.016 0.016 0.018 4 4.15 4.14 4.10 4.10 4.09 0.019 0.018 0.022 0.021 0.021 5 4.49 4.43 4.42 4.41 4.35 0.035 0.034 0.036 0.036 0.036 6 4.20 4.20 4.18 4.18 4.15 0.022 0.022 0.024 0.025 0.025 7 4.69 4.67 4.65 4.61 4.60 0.033 0.034 0.035 0.035 0.038 8 4.15 4.15 4.14 4.12 4.12 0.018 0.018 0.020 0.021 0.024 9 4.28 4.26 4.25 4.25 4.24 0.009 0.010 0.012 0.012 0.013 10 4.59 4.58 4.52 4.50 4.48 0.033 0.033 0.032 0.034 0.035 11 4.39 4.38 4.35 4.31 4.30 0.029 0.029 0.031 0.033 0.034 12 4.45 4.41 4.39 4.38 4.38 0.031 0.035 0.036 0.037 0.037 13 4.50 4.46 4.42 4.41 4.40 0.033 0.035 0.036 0.036 0.037 14 4.40 4.40 4.38 4.32 4.30 0.030 0.031 0.033 0.035 0.036 Evaluation and Comparison of Plating Characteristics Samples of Examples 1-33 comprise commercially available resins, polymer alloys, and amorphous silica with a specific size and shape. Samples of Comparative Examples 1-14 were made by blending conventional inorganic fillers. Although the required plate adhesion strength differs depending on the application, the strength should be at least about 1 kg/cm. As can be seen in Tables 3-1 to 3-2, no test leaves of Examples 1-33 were peeled in the surface peelability test after etching with alkali (a KOH aqueous solution). In addition, all these test leaves exhibited an adhesion strength greater than 1 kg/cm. As can be seen in Tables 5 and 7, the composition of the Comparative Example 1 blended with glass fiber exhibited peeling of the surface layer after chemical etching, indicating poor plating strength. The external appearance of the plated surface was also poor. On the other hand, Tables 5 and 7 show that all test leaves of the Comparative Examples 2-14 exhibited adequate plating characteristics. There was no peeling in the surface peelability test after chemical etching and all these test leaves exhibited an adhesion strength greater than 1 kg/cm. Evaluation and Comparison of Electrical Characteristics As indicated in Tables 4-1 to 4-2, test leaves made from compositions of Examples 1-33 comprising amorphous silica had a dielectric constant of 4.0 or less at all wavelengths. Some exhibited a dielectric constant of 3.0 or less. In addition, all these test leaves had a dielectric loss tangent of 0.01 or less, showing superior electrical characteristics of the resin composition of the present invention comprising amorphous silica. In contrast, as can be seen in Table 8, all test leaves of the Comparative Examples 1-14 exhibited both a high dielectric constant and a high dielectric loss tangent, indicating remarkably impaired electrical characteristics for these test leaves as compared with those of the present invention. As illustrated above, the resin composition for plating of the present invention has both excellent plating characteristics and excellent electrical characteristics. The composition is useful as a material for electric and electronic parts used in high frequency ranges.

Claims: A resin composition for plating comprising a thermoplastic resin and amorphous silica of the chemical formula SiO 2 which has an average particle diameter of 0.01 to 100 µm and an aspect ratio of 10 or less. The resin composition for plating according to claim 1, wherein the amorphous silica has a purity of 96% or more and the content of the amorphous silica is from 5 to 70 wt%. The resin composition for plating according to claim 1 or claim 2, wherein the thermoplastic resin is a polymer alloy consisting of polyether imide and polyphenylene ether.

Inventors: IWAFUNE MASATOSHI, MIZOGUCHI TAKASHI, IWAFUNE, MASATOSHI, MIZOGUCHI, TAKASHI
Applicants: COSMO OIL CO LTD, COSMO SOGO KENKYUSHO KK, COSMO OIL COMPANY, LTD, COSMO RESEARCH INSTITUTE
Application year: 1996
Main classification: C08K3
IPC codes: C08L79, C08J7, C08K3, C08L71, H05K1, H05K3, G03F7