JPH0414448B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a method for manufacturing a single-sided insulator in which one side of a foil-like conductor is insulated with an electrodeposited layer. The obtained single-sided insulated conductor is used as a flexible printed wiring board, an electrode shield material, etc.

BACKGROUND ART Conventionally, a masking film adhesion method has been known as an electrodeposited layer forming method in a method for producing a single-sided insulated conductor. In this method, a masking film is adhered to the non-insulated surface of a foil-like conductor, and the film is immersed in an electrodeposition bath to form an electrodeposition layer on only one side, and then the film is removed.
However, this method has the disadvantage that it requires a masking film, its adhesion process, and removal process.

On the other hand, the group to which the present inventors belong has previously proposed a method that overcomes the above drawbacks. These are the roll close-contact method and the two-layer overlapping method. In the former method, a foil-like conductor is closely introduced into a roll partially immersed in an electrodeposition bath, and passed through the electrodeposition bath to form an electrodeposited layer on the other side. In this method, two conductor sheets are overlapped and introduced into an electrodeposition bath by immersion, and an electrodeposition layer is formed on the surface other than the overlapped surface.

The present invention provides a method for manufacturing a single-sided insulated conductor, characterized in that the electrodeposition layer is formed by contacting one side of the electrodeposition paint. This was done for the purpose of developing something that does not essentially belong to masking methods.

DISCLOSURE OF THE INVENTION The method for producing a single-sided insulated conductor of the present invention involves continuously introducing a sheet of foil-like conductor with both sides unmasked into a state in which only one side is in contact with an electrodeposition paint in an electrodeposition bath, While the foil conductor passes through the electrodeposition bath section, it is subjected to electrodeposition treatment to form an electrodeposition layer on one side of the foil conductor, and the obtained electrodeposition layer-formed conductor is subjected to a baking treatment.

The foil conductor used in the present invention includes:
For example, the thickness is 5 to 500 μm, preferably 10 to 200 μm,
Particularly preferred are metal foils such as copper foil, aluminum foil, and iron foil with a thickness of 15 to 100 μm. The width is generally 5 to 200 cm, but is not limited to this.

Examples of electrodeposition paints include dispersion-type or solution-type anionic or cationic paints using water or a mixed solvent of water and an organic solvent. Examples include one or more of the group consisting of acrylonitrile, methacrylonitrile, acrylic esters, methacrylic esters, acrolein, etc., and glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, acrylamide, methylol acrylamide, and ethyl acrylamide. One or more of the group consisting of rollacrylamide, etc., and one of the group consisting of acrylic acid, methacrylic acid, ethyl acrylic acid, crotonic acid, maleic acid, fumaric acid, etc.
The degree of polymerization is 10,000 to 10,000, which is copolymerized by appropriately reacting a species or two or more species, or is further blended with styrene or a styrene derivative such as alkylstyrene, divinylbenzene, or chlorostyrene.
Examples include varnish that has the ability to form a cross-linked structure by baking a resin dispersed in water. Of course, the electrodeposition paint is not limited to those mentioned above.

In the method of the present invention, first, a sheet of foil-like conductor, both surfaces of which are unmasked, is continuously introduced into the electrodeposition bath so that one surface thereof is in contact with the electrodeposition paint. The introduction method includes, for example, an overflow method (the first
Figure), the electrodeposition paint is supplied from below through a perforated plate,
A method in which an electrodeposition paint layer is formed on the upper part of a porous plate and introduced into this layer, and an electrodeposition paint 10 is supplied from the side of the plate 21 serving as an electrodeposition bath 9 to form an electrodeposition paint layer on the upper part of the plate. The method of introducing this layer into this layer (Figure 2)
Examples include a method in which the agent is introduced onto the surface or surface layer of the electrodeposition paint in a relatively large pool-like electrodeposition bath. Of course, the method is not limited to the above method. In addition, in the method using the above-described porous plate or plate, the plate may also serve as an electrode in the electrodeposition bath. On the other hand, the end portion of the foil conductor to be introduced may be bent to prevent the electrodeposition paint from flowing into the surface of the conductor that is not subjected to electrodeposition treatment.

FIG. 1 represents the method of the present invention applying the above-mentioned overflow method. That is, first, the electrodeposition paint 10 is caused to overflow from the electrodeposition bath 9, and the foil-like conductor 2 is continuously introduced into the overflow liquid so that one side thereof is in contact with the overflow liquid. This establishes a contact state between one side of the foil-like conductor and the electrodeposition paint, thereby making it possible to carry out the electrodeposition process. In the illustrated embodiment, the foil conductor sent out from the take-up roll 1 is continuously introduced into the overflow liquid via direction change rolls 3 and 4. Also, if there is an excess of overflow liquid,
It is received in the outer groove 9b of the electrodeposition bath and returned to the main tank 9a of the bathtub together with the newly supplied electrodeposition paint via the circulation pump 7 and the connecting pipe 8. In this way, the overflow state of the electrodeposition paint is maintained. Width of the bathtub of the electrodeposition bath in the overflow method - Main tank 9 in the example
The width of a is made narrower than the width of the foil-like conductor to be introduced in order to prevent the overflow liquid from reaching surfaces other than the contact surface with the overflow liquid of the foil-like conductor (in the example, the upper surface). Furthermore, it is preferable that the electrodeposited layer is formed only on one side of the foil-like conductor. The degree to which the width is narrowed is appropriately determined depending on the electrodeposition conditions such as the viscosity of the electrodeposition paint, the overflow state, and the introduction speed of the foil conductor. In normal cases, the degree is 5~
20mm is appropriate. That is, it is appropriate that the outer surface of the bathtub be located on both sides so that the outer surface of the bathtub is located approximately 2.5 to 10 mm inside the end of the foil conductor.

Next, the introduced foil-like conductor 2 is passed through an electrodeposition bath section while being in contact with the overflow liquid of the electrodeposition paint, and while passing through, the foil-like conductor 2 is subjected to electrodeposition treatment and electrodeposited on one side (contact surface) of the foil-like conductor. form a layer. In this way, an electrodeposited layer-formed conductor 12 having an electrodeposited layer on one side is obtained. The electrodeposition process is performed by applying a potential difference (electrodeposition voltage) between the foil conductor and the electrodeposition paint. applies an electrodeposition voltage via the plate electrode 6. In the electrode in the figure, since the electrodeposition paint is anionic, the roll electrode is used as the anode. In addition, when the plate electrode 6 is provided in the electrodeposition paint, it is preferable to use a porous plate such as a net for the plate electrode in order to prevent disturbance of the overflow liquid level. Further, reference numeral 11 denotes a direction change roll, which, together with the opposing direction change roll 4, is provided as close as possible to the electrodeposition bath. The gap between the direction change rolls 4 and 11 is made as narrow as possible to prevent or suppress the deflection of the foil conductor between them, and to maintain a planar contact state between the foil conductor and the overflow liquid to reduce the thickness. This is to form an electrodeposited layer with excellent uniformity. General electrodeposition processing conditions at room temperature include an electrodeposition voltage of 1 to
Appropriate values include 60V, an introduction and passage speed of 1 to 10 m/min, a solid content concentration of the electrodeposition paint of 10 to 25%, and a passage (treatment) time of 1 to 60 seconds.

Next, the obtained electrodeposited layer-forming conductor 12 is subjected to a baking treatment, but in the present invention, it is preferable to perform a solvent treatment and a prebaking treatment prior to the baking treatment.

In the figure, 13 is a solvent treatment chamber for treating the electrodeposition layer in the electrodeposition layer forming conductor 12 with a solvent. Treating the electrodeposited layer with a solvent has the advantage that coagulation between the electrodeposited resin particles is promoted, making it easier to form an electrodeposited insulating layer that is free from pinholes and has excellent insulation properties. In this case, examples of solvents used include alcohols such as ethylene glycol and glycerin, ethylene glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol dibutyl ether, and ethylene glycol monophenyl ether, N,N-dimethylformamide, and N,N-dimethylformamide. -dimethylacetamide, N
- a nitrogen-containing solvent such as methyl-2-pyrrolidone,
Examples include hydrophilic solvents such as dimethyl sulfoxide. Alternatively, it may be treated with high temperature (300 to 600°C) steam. In particular, N,N-dimethylformamide, N,N-dimethylacetamide, etc. are preferably used. It is more preferable to treat with these solvents in vapor state. The solvent treatment is appropriately determined depending on conditions such as the type of solvent and temperature, but usually 3 to 30 seconds is sufficient.

On the other hand, the pre-baking process is to smoothly perform the subsequent main baking process, and is performed in the pre-processing chamber 14 at a temperature of 1/3 to 3/5 of the main baking temperature for 5 seconds to 2 minutes. This is done by passing. This treatment is preferably performed in a non-oxidizing atmosphere in order to prevent or suppress oxidation of the surface of the foil conductor that does not have an electrodeposited layer (exposed surface), but since the treatment temperature is relatively low, it is preferable to perform this treatment in an air atmosphere. It's okay.

The baking treatment is performed to heat-treat the electrodeposited layer-forming conductor 12, which has been subjected to solvent treatment and prebaking treatment as necessary, to firmly bond the electrodeposition layer and the foil-like conductor. At this time, when an electrodeposition paint having the ability to form a cross-linked structure is used, it is treated to form a cross-linked structure. The baking process is performed by passing through a baking furnace 17 in the figure, but normally
Heat treatment at 300 to 500°C for 10 seconds to 2 minutes is sufficient. Further, in order to prevent or suppress oxidation of the exposed surface of the foil-like conductor, the baking treatment is preferably performed in a non-oxidizing atmosphere such as a rare gas atmosphere such as argon gas, a nitrogen gas atmosphere, or a reducing atmosphere.
In particular, when the purpose is to obtain a single-sided insulated conductor for use as a printed wiring board, the baking process should be performed in a non-oxidizing atmosphere to facilitate the formation and soldering of circuit wiring on the exposed surface. It is preferable. This typically results in a single-sided insulated conductor 18 having an electrodeposited insulating layer with a thickness of 5 to 100 μm.

In the figure, 15, 16, 19 are direction change rolls, and 20 is the obtained single-sided insulated conductor 18.
This is a winding roll. On the other hand, in some cases, for removing both ends of the obtained single-sided insulated conductor,
Alternatively, a cutting means such as a cutter (not shown) may be provided between the roll 19 and the take-up roll 20 to obtain a width suitable for the purpose.

Advantages of the Invention According to the present invention, single-sided insulated conductors can be obtained continuously and efficiently using a simple device without masking the foil-like conductor, simple operations, and a small number of steps. In addition, the thickness of the electrodeposited insulating layer can be easily adjusted, and the electrodeposited insulating layer, which has excellent thickness uniformity and excellent insulating properties even if it is thin, can be applied directly to only one side of the foil conductor. , and
It also has the advantage that it can be formed in a strong adhesive state and does not require a bonding material such as an adhesive.

In addition, the obtained single-sided insulated conductor has excellent flexibility, insulation properties, and smoothness of the insulating layer, and is also relatively heat resistant and can be directly soldered. and are difficult to peel off. As a result, it has advantages of excellent reliability and long-term stability, and is preferably used as flexible printed wiring boards, electromagnetic shielding materials, etc.

Example: Acrylic water-dispersed electrodeposition paint (solid content 15%, PH4.5, V-551-
20; manufactured by Ryoden Kasei Co., Ltd.) from the electrodeposition bath 9, the electrodeposition paint is supplied into the main tank through the circulation pump 7 and the connecting pipe 8, causing the electrodeposition paint to overflow. , this state was maintained. The height of the overflow liquid is approximately 5 mm above the top of the main tank.
It was hot.

Next, the width of the overflow liquid that is formed is
A copper foil of 160 mm and 35 μm thick was continuously introduced at a speed of 3 m/min. Both ends of the copper foil are connected to the main tank 9, respectively.
It was in a state where it protruded 5 mm from the outer surface of a. In addition, the overflow liquid that came into contact with one side of the copper foil
It was in such a state that it was spread all over the width of the copper foil.

Then, the copper foil was electrodeposited while maintaining the above state. That is, it was passed through an electrodeposition bath section.
Electrodeposition processing conditions were: electrodeposition voltage 15V, temperature 25℃, current application time approximately 4 seconds (introduction passage speed 3m/min), anode:
It was made of copper foil.

Subsequently, the obtained electrodeposited layer-forming conductor 12 was coated with N,N
- The electrodeposited layer was introduced into the solvent treatment chamber 13 in which a dimethylformamide vapor atmosphere was formed, and the electrodeposited layer was treated with the solvent for 15 seconds.

Thereafter, the solvent-treated conductor 12 was heated to 180°C.
The electrodeposited layer was dried by introducing it into a pretreatment chamber 14 in an air atmosphere at a temperature of 0.degree. C. and performing a prebaking process for 30 seconds.
Finally, the prebaked conductor 12 is heated to
Introduced into baking furnace 17 at 360℃ and nitrogen atmosphere.
The single-sided insulated conductor 18 having the electrodeposited layer forming a bridged structure was obtained by heat treatment for several seconds. The thickness of the electrodeposited insulating layer was 40 μm. Further, it was not possible to peel off the electrodeposited insulating layer from the single-sided insulated conductor.

The properties of the obtained conductor were evaluated by the following method.

(1) Dielectric breakdown voltage A copper plate with a width of 5 mm, a length of 80 mm, and a thickness of 4 mm is placed on the electrodeposited insulating surface of a 10 cm long sample, and a voltage of 500 V/sec is applied between the non-insulated surface of the sample and the copper plate. This was done by applying pressure at a pressure increase rate of .

(2) Soldering heat resistance According to JIS C 6481, soldering was conducted at a temperature of 300°C for 30 seconds.

(3) Heat resistance Testing was conducted in accordance with JIS C 6481 at a temperature of 260°C for 1 hour.

As a result, the dielectric breakdown voltage was 6.0KV, and it passed both the soldering heat resistance and heat resistance tests.

[Brief explanation of drawings]

FIG. 1 is a flowchart of an embodiment in which an overflow method is applied, and FIG. 2 is an explanatory sectional view showing an example of an electrodeposition bath formed using a plate. 2: Foil conductor, 5: Roll electrode, 6: Perforated plate electrode, 9: Electrodeposition bath, 10: Electrodeposition paint, 12: Electrodeposition layer forming conductor, 13: Solvent treatment chamber, 14: Pretreatment chamber, 17 : Baking furnace, 18: Single-sided insulated conductor, 2
1: Board.

Claims (1)

[Scope of Claims] 1. A sheet of foil-like conductor with both sides unmasked is continuously introduced into a state in which only one side is in contact with the electrodeposition paint in the electrodeposition bath, and the foil-like conductor is exposed to the electrodeposition paint in the electrodeposition bath. 1. A method for manufacturing a single-sided insulated conductor, which comprises performing electrodeposition treatment to form an electrodeposition layer on one side of a foil-like conductor while passing through a bath, and baking the obtained electrodeposition layer-formed conductor. 2. The method according to claim 1, wherein the electrodeposited layer-forming conductor is treated with a solvent and then subjected to a baking treatment.