JPS6142822A - Method of producing low dielectric constant copper-lined insulating film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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 with a glass base material with a low dielectric constant are widely used as high-frequency printed circuit boards, but these are made by impregnating the glass base material with an emulsion of fluororesin, pre-drying it, and then applying fluorocarbon resin. Laminate resin-impregnated glass substrates to a specified thickness, and then layer copper foil to 50k.
A process in which copper-clad laminates are manufactured by holding the temperature at around 400°C for several hours under pressure of about g/cJ, or by molding fluororesin into a sheet with a predetermined thickness for flexible substrates. For example, a fluororesin raw material is fired to make an ingot, the ingot is cut into a film, rolled, and then heat treated to activate the surface of the sheet. After treatment to improve adhesion, a copper-clad board is manufactured by continuously pasting copper foil, or by melt-bonding the copper foil in a film heat treatment process.

However, all of the above methods require many steps, 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, and was made in an aqueous dispersion of a fluororesin.

Using a liquid obtained by emulsion polymerization of a vinyl monomer that has good thermal decomposition properties at high temperatures as an electrodeposition coating, an electrodeposition layer is formed using an electrodeposition coating method on a copper foil that has been polymerized with a fibrous base material. Then, if necessary, the deposited layer is treated with an organic solvent, and then heated at a high temperature for a short time to decompose and volatilize the vinyl resin in the deposited layer.

This paper proposes a method for manufacturing low dielectric constant copper-clad insulation films that is economical, highly reliable, and capable of continuous production.

[Results of invention]

In the present invention, the object to be coated is a material obtained by polymerizing a fibrous base material on a copper foil. As the fibrous base material used here, glass m I11+ is mainly used, and quartz fiber is suitable from the viewpoint of low dielectric constant, such as glass cloth (manufactured by Arisawa Seisakusho, EPCO50, EPCI02, EPC160, LP).
CO70, LPCIIO, etc.) can be used.

Examples of the fluororesin used in the present invention include polytetrafluoroethylene, polytrifluorochloroethylene, polyvinyl fluoride, polyvinylidene fluoride, dichlorodifluoroethylene, etc., and preferred ones include:
Examples include polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, etc.
The aqueous dispersion is optionally used, such as Teflon 120 or Teflon 30 manufactured by Mitsui Fluorochemical Co., Ltd.
-J etc.

In the present invention, it is used for emulsion polymerization in an aqueous dispersion of a fluororesin. The vinyl monomer used is one that is thermally decomposable at high temperatures, such as one or more of acrylic esters and methacrylic esters such as ethyl acrylate, butyl acrylate, methyl methacrylate, and butyl methacrylate. There are nine things that are suitable. These vinyl monomers play the role of a binder during electrodeposition of the aqueous dispersion of fluororesin, help form a tight electrodeposited layer, and facilitate film formation during heating.

The vinyl monomer is an aqueous dispersion of fluororesin 10
It is used in an amount of 3 to 20 parts by weight, preferably 5 to 10 parts by weight, based on 0 parts by weight (solid content). 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, the amount of extrusion will increase during thermal decomposition and pinholes will easily occur.

When emulsion polymerizing a vinyl monomer in an aqueous dispersion of a fluororesin, nonionic, anionic, or cationic surfactants are used as emulsifiers, but anionic surfactants are preferably used from the viewpoint of electrodepositivity. Examples include sodium lauryl sulfate, sodium dodecyl sulfate, sodium oleyl sulfate, sulfate ester salts of saturated or unsaturated higher alcohols such as -, l+, and sulfonates such as sodium dodecyl sulfonate and sodium dodecylbenzenesulfonate. The amount of the emulsifier used is not particularly limited, but from the viewpoint of electrodepositivity and emulsion stability, it is preferably 0.5 to 5 parts by weight per 100 parts by weight of the vinyl monomer.

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 11 are particularly preferred. It can be given as something. The amount of these polymerization initiators is 0.01 to 100 parts by weight of vinyl monomer.
It is used appropriately within a range of 10 parts by weight.

When a vinyl monomer is emulsion polymerized in an aqueous dispersion of a fluororesin, a vinyl resin that coats the fluororesin and adheres to the sea urchin is obtained, which can be used as it 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 to serve as an anode, and when a direct current is passed between it and the counter electrode, electrodeposition coating is performed. 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, dimethylsulfonamide, and ethyl cellosolve. Methods for organic solvent treatment include immersion in a solvent solution or contact with steam.

When the electrodeposited prayer layer thus treated 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.
The temperature is appropriately selected within the range of ~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 described 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 Wi-making method, a copper foil (1) and a fibrous base material (glass cloth) (2) are sent out, and then rolled to a roller (3).

The polymerized state obtained by (4) is sent via a roller (5) to an electrodeposition bath (8) provided with a counter electrode (7) by a roller (6) whose surface is insulated, and then A voltage is applied by the DC voltage 1 (13) from the point of contact, and an electrodeposited 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, the electrodeposited layer is heated to a roller (11). ) through winding M&(1
2) Winding up and rolling 6 Reference example: Manufacture of electrodeposition paint An example of a method for manufacturing the electrodeposition paint used in the present invention will be described below. First, polytetrafluoroethylene dispersion (Teflon 30-J, 'e
jN content 60%, manufactured by Mitsui Fluorochemical Co., Ltd.) 20Q, ion exchange water 102, and lauryl sulfate ester soda 6 g were added, stirred for 30 minutes through nitrogen gas, heated to 70 ° C., and added 6 g of ammonium persulfate and 2 g of sodium hydrogen sulfite. A solution dissolved in 20 g of ion-exchanged water is added, and 600 g of methyl methacrylate is immediately added dropwise over 30 minutes. After the addition is complete, the mixture is reacted at 70° C. for 2 hours. Next, ion-exchanged water is added 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 of 500 mm width and 35 μm thickness according to the manufacturing method shown in the figure, and the copper foil side was A DC voltage of 50 V is applied to the anode to form an electrodeposited layer. Next, this deposited layer is treated with organic solvent vapor, then heat-treated by electrical heating at the maximum temperature shown in Table 1, cooled, and then rolled up to obtain a copper-clad insulating film. The characteristics are also listed in Table 1. Note that the speed of the copper foil is preferably 1 to 1 oIl/min, but is not limited to this.

As is clear from the examples in Table 1, the insulating film according to the present invention has a lower vI electric current than the glass/epoxy film of the comparative example, and also has a very low dielectric loss tangent. Furthermore, in this embodiment, on the higher frequency side (IM)lz or higher),
Further, it is expected that the difference will become larger due to precipitation in glass/epoxy.

In the above description, the water-based ice version of the fluororesin, the vinyl monomer, the heating method, etc. are not limited to those exemplified above, and may be changed. Furthermore, the present invention is applicable not only to high-frequency printed circuit boards but also to the production of copper-clad insulating films for other uses.

〔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 insulation film can be manufactured continuously, economically and with high reliability. can do.

[Brief explanation of the drawing]

The figure is a system diagram showing one embodiment of the present invention, in which (1) is a copper foil, (2) is a fibrous base material, (3) to (6), and (11).
is a roller, (7) is a counter electrode, (8) is an electrodeposition bath, (9)
is an organic solvent vapor tank, and (io) is a heating furnace.

Claims (4)

[Claims] (1) An electrodeposited layer is formed on a copper foil with a polymerized fibrous base material by electrodeposition using a liquid obtained by emulsion polymerization of a vinyl monomer with good thermal decomposition in an aqueous dispersion of fluororesin as an electrodeposition coating. 1. A method for producing a low dielectric constant copper-clad insulating film, which comprises forming an insulating film by decomposing and volatilizing a vinyl polymer by heating. (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.