JPH0419655B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a method for producing a low dielectric constant copper-clad insulating film such as a copper-clad laminate used in high-frequency equipment. [Prior art] In general, fluororesin substrates containing a glass base material with a low dielectric constant are widely used as high-frequency printed circuit boards. Pre-dry,
After that, the fluororesin-impregnated glass base material is laminated to a specified thickness, and then copper foil is layered and applied to a pressure of about 50 kg/ ^cm2.
A copper-clad laminate is produced by maintaining the temperature around 400℃ for several hours, or a process of forming a fluororesin into a sheet with a predetermined thickness to make a flexible substrate, such as a fluororesin raw material. After firing the ingot to make an ingot, cutting it into a film, rolling it, and heat-treating it, the surface of the resulting sheet is activated to improve its adhesion. A copper-clad board is manufactured by continuously pasting copper foil, or by melting and adhering copper foil during a film heat treatment process. However, many steps are required in any of the above methods, and in order for fluororesin substrates to be widely adopted as high-frequency substrates in the future, it is essential to reduce manufacturing costs by simplifying the steps. [Summary of the Invention] The present invention was made for the purpose of improving the above-mentioned drawbacks.
A liquid obtained by emulsion polymerization of a vinyl monomer that has good thermal decomposition properties at high temperatures is used as an electrodeposition coating, and an electrodeposition layer is formed using the electrodeposition coating method on copper foil overlaid with a fibrous base material. Then, if necessary, the precipitated layer is treated with an organic solvent, and then heated at high temperature for a short time to decompose and volatilize the vinyl resin in the precipitated layer, which enables economical, highly reliable, and continuous production. This paper proposes a method for manufacturing a low dielectric constant copper-clad insulation film. [Structure of the Invention] In the present invention, the object to be coated is a fibrous base material superimposed on a copper foil. Glass fiber is mainly used as the fibrous base material used here, and quartz fiber is suitable from the viewpoint of low dielectric constant. For example, glass cloth (manufactured by Arisawa Seisakusho, EPC050, EPC102,
EPC160, LPC070, LPC110, etc.) can be used. Examples of the fluororesin used in the present invention include polytetrafluoroethylene, polytrifluorochloroethylene, polyvinyl fluoride, polyvinylidene fluoride, dichlorodifluoroethylene, etc., and preferred examples include polytetrafluoroethylene. , tetrafluoroethylene-hexafluoropropylene copolymer, etc., and its aqueous dispersion can be optionally used. For example, Teflon 120 manufactured by Mitsui Fluorochemical Co., Ltd. and Teflon
Examples include 30-J. In the present invention, the vinyl monomer used for emulsion polymerization in the aqueous dispersion of fluororesin is one that has good thermal decomposition properties at high temperatures, such as ethyl acrylate, butyl acrylate, methyl methacrylate, and methacrylate. Preferred examples include one or more of acrylic esters such as butyl esters and methacrylic esters. These vinyl monomers play the role of a binder during the electrodeposition of the aqueous dispersion of fluororesin, assisting in the formation of a tight electrodeposited layer, and facilitating the formation of a film upon heating. The vinyl monomer is used in an amount of 3 to 20 parts by weight, preferably 5 to 10 parts by weight, per 100 parts by weight (solid content) of the aqueous fluororesin dispersion. If it is less than 3 parts by weight, the binder effect will be small and it will be difficult to obtain a uniform film, and if it exceeds 20 parts by weight,
During thermal decomposition, the amount of volatilization increases, making pinholes more likely to occur. In emulsion polymerization of vinyl monomers in an aqueous dispersion of fluororesin, nonionic, anionic, and cationic surfactants are used as emulsifiers, but anionic surfactants are preferably used from the viewpoint of electrodepositivity. Examples include sulfuric acid ester salts of saturated or unsaturated higher alcohols such as sodium lauryl sulfate, sodium dodecyl sulfate, and sodium oleyl sulfate, and sulfonic acid salts such as sodium dodecyl sulfonate and sodium dodecylbenzene sulfonate. There is no particular limit to the amount of emulsifier used, but from the viewpoint of electrodeposition and emulsion stability, it is 0.5 to 0.5 parts by weight per 100 parts by weight of vinyl monomer.
5 parts by weight is preferred. As the polymerization initiator used for emulsion polymerization of the vinyl monomer, ordinary initiators can be used without any restrictions, but redox initiators such as potassium persulfate-sodium hydrogen sulfite and ammonium persulfate-sodium hydrogen sulfite are particularly preferred. It can be given as a thing. The amount of these polymerization initiators is suitably used in the range of 0.01 to 10 parts by weight based on 100 parts by weight of the vinyl monomer. When a vinyl monomer is emulsion polymerized in an aqueous dispersion of a fluororesin, a vinyl resin that adheres to the fluororesin is obtained and used as is as an electrodeposition paint. The object to be coated is immersed in an aqueous dispersion obtained by emulsion polymerization of a vinyl monomer in an aqueous dispersion of fluororesin, which serves as an anode, and a direct current is passed between it and the counter electrode to perform electrodeposition coating. Then, the resin adheres to the object to be coated by electrophoresis, forming an electrodeposited layer. Electrodeposition conditions can be suitably implemented with an applied voltage of about 5 to 100 V depending on the required film thickness. When heating the electrodeposited layer obtained above to form a continuous film, in order to facilitate film formation, a hydrophilic organic material that dissolves or swells the vinyl resin in the electrodeposited layer is used before heating. Solvent treatment is useful. Suitable hydrophilic organic solvents include polar solvents such as N-methylpyrrolidone, dimethylformamide, dimethylacetamide, dimethylsulhomoside, and ethyl cellosolve. Methods for organic solvent treatment include immersion in a solvent solution or contact with steam. When the electrodeposited layer treated in this manner is heated, the vinyl polymer is decomposed and volatilized, and water is also removed, forming a continuous film. The heating temperature varies depending on the thermal decomposition temperature of the vinyl resin used and the thermal spraying temperature of the fluororesin, but is appropriately selected within the range of 400 to 600°C. Various methods can be employed as the heating method, but suitable methods include electrical heating, induction heating, oven heating, etc. in order to rapidly decompose and volatilize the vinyl resin in the electrodeposited layer. [Embodiments of the Invention] Hereinafter, embodiments of the present invention will be explained with reference to the drawings.
The figure is a system diagram showing a manufacturing method according to an embodiment of the present invention. In the manufacturing method, a copper foil 1 and a fibrous base material (glass cloth) 2 are sent out, and rollers 3 and 4
The polymerized state is sent via a roller 5 to an electrodeposition tank 8 provided with a counter electrode 7 by a roller 6 whose surface is insulated, and a voltage is applied by a DC power source 13 from the point in contact with the roller 6 to generate an electric current. A deposited layer is formed. Next, after the electrodeposited layer is treated in an organic solvent vapor tank 9, water, organic solvent, and binder are decomposed and volatilized in a heating furnace 10 to form a copper-clad insulating film, and after cooling, it is rolled up via a roller 11. It is wound up by the machine 12. Reference Example: Structure of Electrodeposition Paint An example of the method for manufacturing the electrodeposition paint used in the present invention will be described below. First, place polytetrafluoroethylene dispersion (Teflon 30-
J, resin content 60%, manufactured by Mitsui Fluorochemical Co., Ltd.) 20
Add 10 g of ion-exchanged water and 6 g of lauryl sulfate ester soda, stir for 30 minutes through nitrogen gas, raise the temperature to 70°C, and add 6 g of ammonium persulfate,
Add a solution of 2 g of sodium bisulfite dissolved in 20 g of ion-exchanged water, and immediately add methyl methacrylate.
600g was added dropwise over 30 minutes, and after the addition was completed, the reaction was allowed to proceed at 70°C for 2 hours. Next, add ion-exchanged water to obtain an aqueous dispersion with a total nonvolatile content of 20%. Examples 1 to 7 Using the electrodeposition paint shown in Table 1, the fibrous base material shown in Table 1 was polymerized on a continuous copper foil with a width of 500 mm and a thickness of 35 μm according to the manufacturing method shown in the figure, and the copper foil side was A DC voltage of 50 V is applied as an anode to form an electrodeposited layer. Next, this deposited layer was treated with organic solvent vapor, and then heat-treated by electrical heating at the maximum temperature shown in Table 1,
After cooling, a copper-clad insulating film is obtained by winding it up. The characteristics are also listed in Table 1. Note that the speed of the copper foil is 1
~10 m/min is preferably used, but is not limited thereto.

【table】

〔Effect of the invention〕

According to the present invention, after forming an electrodeposited layer using a fluororesin solution containing a binder, the binder is volatilized, so that a low dielectric constant copper-clad insulating film can be continuously formed economically and with high reliability. can be manufactured.

[Brief explanation of drawings]

The figure is a system diagram showing an embodiment of the present invention.
1 is a copper foil, 2 is a fibrous base material, 3 to 6, 11 are rollers, 7 is a counter electrode, 8 is an electrodeposition bath, 9 is an organic solvent vapor bath, and 10 is a heating furnace.

Claims (1)

[Scope of Claims] 1. Electrodeposition coating using a liquid obtained by emulsion polymerization of a vinyl monomer with good heat decomposition properties in an aqueous dispersion of fluororesin as an electrodeposition paint on a copper foil overlaid with fibrous base materials. A method for producing a low dielectric constant copper-clad insulating film, which comprises forming an electrodeposited layer by heating, decomposing and volatilizing the vinyl polymer by heating, and forming an insulating film. 2. The manufacturing method according to claim 1, wherein the fibrous base material is glass cloth. 3. The manufacturing method according to claim 1 or 2, wherein the vinyl monomer is methyl methacrylate. 4. The manufacturing method according to any one of claims 1 to 3, wherein the heating is electrical heating.