JP2011099157A - Formed circuit component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure the insulation of a portion which is not formed into a circuit and to improve adhesiveness in electroless plating by preventing occurrence of ion migration. <P>SOLUTION: In a formed circuit component, an electroless copper plating layer 3 is formed selectively on the surface of an insulating substrate 1 which is prepared by mixing a thermoplastic resin with a filler comprising multi-needle crystal particles of zinc oxide. In that case, the filler existing in the surface layer of the substrate is removed by an etching liquid before forming the electroless copper plating layer. The filler-removed surface layer of the substrate 1 exerts excellent anchoring effect with respect to the copper plating layer 3, and can prevent occurrence of ion migration in the portion 1b which is not formed into a circuit. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a molded circuit component in which an electroless plating layer is selectively formed on the surface of an insulating substrate.

  Conventionally, there has been provided a molded circuit component in which a conductive circuit is formed by selectively performing electroless plating on the surface of an insulating substrate. In this molded circuit component, in order to ensure the adhesion between the surface of the insulating substrate and the electroless plating, the surface of the insulating substrate is usually roughened in advance for the portion to be subjected to electroless plating. The adhesiveness of electroless plating is ensured (for example, refer patent document 1). As one of the means for roughening the surface of the insulating substrate, the insulating substrate is mixed with a filler of, for example, a rubber substance that is easily dissolved by the etching solution, and the etching solution is applied to the surface layer portion of the insulating substrate. There are means for dissolving the filler to be mixed. (For example, refer to Patent Document 2.)

  Conventionally, fillers have also been used to improve the strength and rigidity of insulating substrates. In order to improve the strength, rigidity, etc. of these insulating substrates, inorganic fillers such as glass fibers, glass beads, carbon fibers, metal fibers, or zinc oxide whiskers have been proposed (for example, Patent Document 3). reference.).

  By the way, in recent years, zinc oxide multi-needle crystal grains, that is, zinc oxide crystal grains having a shape in which a large number of needle crystals grow radially from the center have been developed and commercialized. For example, a product “Panatetra” (registered trademark) manufactured by Amtec Corporation is commercially available. It is said that by mixing this “Panatetra” with a synthetic resin, excellent moldability, wear resistance, antistatic properties, and radio wave shielding properties can be obtained.

  As described above, since the zinc oxide multi-needle crystal grains have a large number of needle crystals grown radially from the center, it is ideal for obtaining an anchor effect for ensuring the adhesion of electroless plating. Can be thought of as the target. In other words, if multi-needle crystals of zinc oxide are mixed in an insulating substrate and the zinc oxide multi-needle crystals existing on the surface of the insulating substrate can be removed, the multi-needle crystals are removed. Since the cavities are radially branched in all directions, if electroless plating penetrates into these cavities, extremely good adhesion can be obtained.

JP-A-11-145583 JP 2006-240085 A JP 2000-239422 A

  However, zinc oxide crystals are easily ionized by dissolving in acid and alkaline aqueous solutions. For this reason, when a voltage is applied in a humid atmosphere, an insulating substrate mixed with zinc oxide crystals is reduced to metal zinc, so-called ion migrainin is generated, and a short circuit between the circuits is likely to occur. There is a problem. Moreover, since the multi-needle-like crystal grains of zinc oxide have conductivity, it is conceivable that the insulating properties of the non-circuit portions where electroless plating is not formed are reduced. For this reason, with respect to the molded circuit component that forms the conductive circuit by selectively performing electroless plating on the surface of the insulating substrate, in order to improve the adhesion between the insulating substrate and the electroless plating, The use of multi-needle crystal grains as a filler has not been performed.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a molded circuit component that prevents the occurrence of ion migration and secures the insulation of a non-circuit portion and that has extremely excellent electroless plating adhesion.

  As a result of diligent research, the inventors of the present application have removed the zinc oxide multi-needle crystal particles mixed in the surface layer by etching the surface of the thermoplastic resin mixed with zinc oxide multi-needle crystal particles with an etching solution. As a result, it was found that an ideal anchoring effect for electroless plating can be obtained, the occurrence of ion migrainin can be prevented, and the electrical insulation of a non-circuit portion can be secured. It was.

  That is, the feature of the molded circuit component according to the present invention is a molded circuit component in which an electroless plating layer is selectively formed on the surface of the insulating substrate, and this insulating substrate is formed of a multi-needle of zinc oxide on a thermoplastic resin. Before the formation of the electroless plating layer, the filler mixed in the surface layer of the insulating substrate is removed by the etching solution, and the insulating substrate is mixed. The electrical insulation resistance of the non-circuit portion is at least 10E9Ω. The mixing ratio of the filler is desirably 5 to 45 parts by weight. Moreover, you may mix 5-20 weight part of the other inorganic filler melt | dissolved in the said etching liquid with the said insulating base | substrate.

  Here, the “molded circuit component” is not limited to a planar two-dimensional shape, but includes a three-dimensional three-dimensional shape and a hollow shape. “Selectively forming an electroless plating layer” is a non-circuit in which an electroless plating layer is formed only on a portion of a conductive circuit having a predetermined path shape and the surface of the insulating substrate is exposed in the remaining portion. It means to become a part. The “thermoplastic resin” preferably has acid resistance and alkali resistance, such as polyetherimide, polysulfone, polyethylene terephthalate, polybutylene terephthalate, polyphthalamide, aromatic polyester liquid crystal polymer, and polyether ether ketone.

  As described above, “multi-needle crystal grains of zinc oxide” means a shape in which a large number of needle crystals grow radially from the central portion. For example, a product “Panatetra” (amtec Co., Ltd.) ( Registered trademark). “Electroless plating” means so-called normal chemical plating. Electroless copper plating, electroless nickel plating, electroless gold plating, electroless silver plating, or electroless plating with different plating metals, Also includes multi-layered ones. “Etching solution” means a solution for dissolving and removing zinc needle multi-needle crystal grains mixed in the surface layer of an insulating substrate, and includes both an acidic solution and an alkaline solution.

  “10E9Ω” means that the surface resistivity is 10 9 ohms. The reason that “the electrical insulation resistance of the non-circuit portion is at least 10E9Ω” is that conduction is established at 10E8Ω or less. “It is desirable that the mixing ratio of the filler is 5 to 45 parts by weight”. If it is less than 5 parts by weight, the distribution of the zinc oxide multi-needle crystal grains becomes sparse. This is because the anchor effect for electroless plating is lowered. Conversely, when the amount exceeds 45 parts by weight, the distribution of the zinc oxide multi-needle crystal grains becomes dense, and the electrical insulation of the non-circuit portion is achieved. This is because the resistance decreases. Examples of “other inorganic fillers soluble in the etching solution” include calcium carbonate, calcium silicate, and calcium pyrophosphate.

  The cavity formed by mixing the zinc oxide multi-needle crystal grains in the insulating substrate and removing the zinc oxide multi-needle crystal grains mixed in the surface layer of the insulating substrate with the etching solution is in all directions. Since it becomes a thing branched radially, if electroless plating penetrate | invades into this cavity, the extremely outstanding adhesiveness will be acquired. In addition, the non-circuit portion that is not covered with electroless plating can also prevent the occurrence of ion migration because the zinc oxide multi-needle crystal grains mixed in the surface layer are removed by the etching solution.

  By setting the mixing ratio of the multi-needle crystal grains of zinc oxide within a predetermined range, the electrical insulation of the non-circuit portion can be ensured. Furthermore, by mixing a material that dissolves in the etching solution, such as calcium carbonate, as an inorganic filler, the cavity from which the calcium carbonate has been removed is connected to the cavity from which the multi-needle crystals of zinc oxide have been removed. The anchor effect for electrolytic plating can be improved.

It is process drawing which shows the manufacturing process of a molded circuit component. It is explanatory drawing explaining the anchor effect with respect to electroless plating.

  A method for manufacturing a molded circuit component according to the present invention will be described with reference to the process chart shown in FIG. In the first step (A), the block-shaped insulating substrate 1 is formed by injection molding. Here, the material of the insulating substrate 1 is 50.1% by weight of polyether ether ketone (for example, product “1000G” manufactured by Daicel Evonik Co., Ltd.), which is a thermoplastic resin, and multi-needle crystal grains of zinc oxide (for example, Amtec Co., Ltd. product “Panatetra (registered trademark) WZ-0501”) 32.6% by weight and calcium carbonate as an inorganic filler (for example, Shiraishi Kogyo Co., Ltd. product “Whiten P-10”) 12.3% by weight To make.

  Next, after degreasing and cleaning the insulating substrate 1 in the step (B), the surface of the insulating substrate is etched with an etchant in the step (C). As an etching solution, for example, an acidic aqueous solution of 400 g of concentrated sulfuric acid and 400 g / liter of chromic anhydride is used, and the insulating substrate 1 is immersed at a temperature of 70 ° C. for 10 minutes.

  Next, after neutralizing and cleaning the insulating substrate 1, in step (D), the surface of the insulating substrate 1 is covered with the masking 2 on the portion 1b that becomes a non-circuit portion, leaving the portion 1a that becomes a circuit. . The masking 2 is molded by injecting an oxyalkylene group-containing polyvinyl alcohol resin (for example, “Ecomati AX” manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) that is water-soluble and easily dissolved in warm water. As masking 2, polylactic acid (for example, “Lacia # H-100J / F” manufactured by Mitsui Chemicals, Inc.) or polyglycolic acid (for example “Kureha Co., Ltd.“ # KSK08 ") or the like may be used.

  In the next step (E), a catalyst is applied to the insulating substrate 1 covered with the masking 2 to form nuclei for depositing electroless plating. As a procedure for applying the catalyst, for example, the insulating substrate 1 is immersed in a mixed catalyst solution of tin and palladium, and then activated with an acid such as hydrochloric acid or sulfuric acid to deposit palladium on the surface. Alternatively, a relatively strong reducing agent such as stannous chloride is adsorbed on the surface and immersed in a catalyst solution containing noble metal ions such as gold to deposit gold on the surface. What is necessary is just to immerse the temperature of a liquid at 15-23 degreeC for 5 minutes.

  In the next step (F), the masking 2 covering the insulating substrate 1 is removed. When the masking 2 is an oxyalkylene group-containing polyvinyl alcohol resin, the insulating substrate 1 covered with the masking 2 is immersed in warm water at 80 ° C. for about 10 minutes to elute the masking in hot water. . When the masking 2 is polylactic acid or polyglycolic acid, it is immersed for about 1 to 120 minutes in a caustic (NaOH, KOH, etc.) aqueous solution having a concentration of 2 to 15% by weight and a temperature of 25 to 70 ° C. Masking 2 is removed.

  In the last step (G), the electroless copper plating layer 3 is formed on the surface 1a of the insulating substrate 1 and on the portion 1a that is not covered with the masking 2 and becomes a circuit. That is, as will be described later, since the cavity from which the multi-needle crystal grains of zinc oxide are removed and the catalyst is applied to the portion 1a to be a circuit, the electroless copper plating layer 3 is formed on the surface and the cavity. It precipitates inside and firmly adheres to this insulating substrate. Specifically, the insulating substrate 1 coated with the masking 2 is applied to a plating solution having an acidic bath composition, for example, 5 to 15 g / L of copper sulfate as a metal salt, and 8 to 37% by volume of a formalin as a reducing agent. It is immersed in a solution at a temperature of 20 ° C. mixed with 12 mL / L, 20-25 g / L of Rochelle salt as a complexing agent, and 5-12 g / L of sodium hydroxide as an alkaline agent.

  The excellent anchor effect for the electroless copper plating 3 will be described with reference to FIG. FIG. 2A shows a cross section of the surface layer of the insulating substrate 1 injection-molded in the step (A) of FIG. 1 described above. That is, the insulating substrate 1 is obtained by mixing a thermoplastic resin 11 with multi-needle crystal grains 12 of zinc oxide and fine calcium carbonate 13 and one of the multi-needle crystal grains of zinc oxide. The part protrudes from the surface. Therefore, when a voltage is applied in this state, the portion protruding from the surface of the zinc oxide multi-needle crystal grains 12 is ionized by moisture in the air, ion migrasin is generated, and a short circuit between the circuits is generated. There is a risk of inviting.

  FIG. 2B shows a cross section of the surface layer of the insulating substrate 1 after etching in the step (C) of FIG. 1 described above. That is, in the zinc oxide multi-needle crystal grains 12, not only a portion protruding from the surface of the insulating substrate 1 but also a portion inside the surface of the insulating substrate is dissolved and removed, and a cavity 14 extending in all directions is formed. The Also, the calcium carbonate 13 in contact with the zinc oxide multi-needle crystal grains 12 is dissolved and removed, and a granular cavity 15 communicating with the cavity 14 is formed.

  FIG. 2B shows a cross section of the surface layer of the insulating substrate 1 on which the electroless copper plating layer 3 is formed in the above-described step (G) of FIG. That is, the electroless copper plating layer 3 is provided not only in the surface portion 31 of the insulating substrate 1 but also in the cavities 14 and granular cavities 15 in which the zinc oxide multi-needle crystal grains 12 and the calcium carbonate 13 are dissolved and removed. Is also formed. Therefore, the electroless copper plating layer 3 is firmly fixed to the surface layer of the insulating substrate 1. In the non-circuit portion 1b where the electroless copper plating layer 3 is not formed, the zinc oxide multi-needle crystal grains 12 and calcium carbonate 13 mixed in the surface layer of the insulating substrate 1 are dissolved and removed. The generation of ion migrainin can be prevented.

  The electroless copper plating three layers can be easily formed not only in the above-described process but also in other processes. For example, the step (D) (masking) and the step (E) (catalyst application) in FIG. 1 can be interchanged. Further, the step (F) (masking removal) and the step (G) (electroless copper plating) can be interchanged. Furthermore, if a catalyst is mixed in the insulating substrate 1 in advance, the step (E) (providing the catalyst) in FIG. 1 can be omitted. In this case, it is necessary to interchange the step (F) (masking removal) and the step (G) (electroless copper plating).

  Further, the insulating substrate 1 is formed of a material that is difficult to plate, and the masking 2 is formed on the surface by a material in which the above-described thermoplastic resin 11 is mixed with the multi-needle crystal grains 12 of zinc oxide and calcium carbonate 13. It is also possible to selectively form the electroless copper plating layer 3 on the surface of the masking 2. Furthermore, an electroless nickel layer or an electrolytic copper plating layer can be easily stacked on the electroless copper plating layer 3.

As thermoplastic resin 11, polyether ether ketone (PEEK) (product “# 1000G” manufactured by Daicel-Evonik Co., Ltd.) 50.1% by mass, as multi-needle crystal grains of zinc oxide (product of Amtec Co., Ltd. “ #Panatetra WZ-0501 ") 32.6 parts by weight and inorganic filler calcium carbonate (CaCO ₃ ) (Shiraishi Kogyo Co., Ltd. product"# Whiten P-10 ") 12.3 parts by weight An insulating substrate 1 is formed using a material, and after degreasing and cleaning, etching is performed in an aqueous solution of 400 g of concentrated sulfuric acid and 400 g of chromic anhydride / liter as a chemical etching agent for 70 ° C./10 minutes, and the surface layer of this insulating substrate As a result of measuring the insulation resistance of the non-circuit portion 1b by completely removing the zinc oxide multi-needle crystal grains 12 and the calcium carbonate 13 mixed together, and forming the electroless copper plating layer 3 described above. We were able to verify is 10 square Ω or more. The adhesion strength of electroless copper plating layer 3 was 2.0 KN / m in the peel test.

  As thermoplastic resin 11, polyether ether ketone (PEEK) (product “# 1000G” manufactured by Daicel-Evonik Co., Ltd.) 62.8% by weight, as zinc oxide needle crystal grains (product of Amtec Co., Ltd. “ #Panatetra WZ-0501 ") Insulating substrate 1 is formed using a composite material containing 37.2 parts by weight, and after degreasing and cleaning, in an aqueous solution of 400 g of concentrated sulfuric acid and 400 g of chromic anhydride as a chemical etching agent. Then, etching is performed at 70 ° C. for 10 minutes to completely remove the zinc oxide needle crystal grains 12 mixed in the surface layer of the insulating base, and the above-described electroless copper plating layer 3 is formed. As a result of measuring the insulation resistance of 1b, it was verified that it was 10 10 Ω or more. The adhesion strength of the electroless copper plating layer 3 was 1.5 KN / m in a peel test.

As thermoplastic resin 11, polyphthalamide (PPA) (Kuraray Co., Ltd. product “#Genesta N1000 M42”) 41.45% by weight, as zinc oxide needle-like crystal grains 12, product of Amtec Co., Ltd. #Panatetra WZ-0501 ") 38.55 parts by weight, and calcium carbonate (CaCO ₃ ) (product of Shiraishi Kogyo Co., Ltd."# Whiten P-10 ") 20 parts by weight as an inorganic filler. The insulating substrate 1 is molded using degreasing, and after degreasing and cleaning, etching is performed at 50 ° C. for 5 minutes in an aqueous solution of 400 g of concentrated sulfuric acid and 400 g of chromic anhydride as a chemical etching agent. As a result of completely removing the mixed zinc oxide needle crystal grains 12, forming the above-described electroless copper plating layer 3, and measuring the insulation resistance of the non-circuit portion 1b, it is 10 to the 10th power Ω or more. But with verification Came. Moreover, the adhesive strength of the electroless copper plating layer 3 was 1.0 KN / m in the peel test.

  As thermoplastic resin 11, liquid crystal polymer (LCP) (product “Vectra # C820” manufactured by Polyplastics Co., Ltd.) is 40% by weight, whereas liquid crystal polymer (LCP) (product “Vectra # A950” manufactured by Polyplastics Co., Ltd.) is used. ) Insulating substrate 1 was molded using a composite material containing 40 parts by weight and 20 parts by weight of Amtec Co., Ltd. product “#Panatetra WZ-0501” as multi-needle crystal grains 12 of zinc oxide. After degreasing and cleaning, this insulating substrate was immersed in an alkaline aqueous solution at a temperature of 70 ° C. dissolved in 45% by weight of caustic soda as a chemical etching agent for 50 minutes to perform etching, and zinc oxide mixed in the surface layer of this insulating substrate The multi-needle crystal grains 12 and calcium pyrophosphate (previously added to “Vectra # C820”) are completely removed, and by known laser patterning Subjecting the road form, the results of the insulation resistance was measured in the non-circuit portion 1b, it was verified to be 10 10 square Ω or more. The adhesion strength of the electroless copper plating layer 3 was 1.0 KN / m in a peel test.

  When the electrochemical migration test (test standard JPCA-ET04-2007 constant temperature and humidity test) was performed at the temperature of 85 ° C. and the relative humidity of 85% on the specimens of Examples 1 to 4 described above, all migrated. It was verified that there was no occurrence of insulation and that the insulation resistance value did not decrease.

  It is possible to prevent the occurrence of ion migration, and to ensure the insulation of the non-circuited portion, and the excellent adhesion of the electroless plating can be widely used in industries related to electronic devices and the like.

DESCRIPTION OF SYMBOLS 1 Insulation base | substrate 1a The part used as a circuit 1b The part used as a non-circuit 2 Masking 3 Electroless copper plating (electroless plating)

Claims (3)

A molded circuit component in which an electroless plating layer is selectively formed on the surface of an insulating substrate,
The insulating substrate is a mixture of a thermoplastic resin and a filler made of zinc oxide multi-needle crystal grains,
Prior to forming the electroless plating layer, the filler mixed in the surface layer of the insulating substrate is removed by an etching solution,
The molded circuit component, wherein the non-circuit portion has an electric insulation resistance of at least 10E9Ω on the surface of the insulating substrate.       2. The molded circuit component according to claim 1, wherein a mixing ratio of the filler is 5 to 45 parts by weight.       3. The molded circuit component according to claim 1, wherein 5 to 20 parts by weight of another inorganic filler dissolved in the etching solution is further mixed with the insulating substrate.

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