JPS6042567B2 - Manufacturing method for electrical laminates - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method of manufacturing an electrical laminate.

More specifically, the present invention relates to a method for producing an electrical laminate with excellent surface smoothness. The electrical laminate used in the present invention refers to a laminate used for laminated insulating boards or copper-clad laminates used as substrates for various electronic components, and its shape is approximately 0.3 to 5 wrm in thickness. It is.

Conventionally, these materials have generally been manufactured using a heating and pressing method using phenol resin based on paper, epoxy resin based on glass cloth, or the like. In addition, a method has been proposed in which a non-adhesive prepreg is formed using an unsaturated polyester resin varnish that is solid at room temperature and has crystallinity, and the prepreg is laminated and manufactured by pressure pressing. However, due to the high quality of raw materials, it has not been fully put into practical use.
On the other hand, when using unsaturated polyester chill resin that is liquid at room temperature, a non-adhesive prepreg cannot be formed.
In addition, during press processing, it is difficult to manufacture using conventional methods due to the high fluidity of the resin and the difficulty of pressure molding. has not been put into practical use at all.

However, when using an unsaturated polyester resin that is liquid at room temperature, for example, a solvent is not required in the process of impregnating the base material, and the curing reaction is radical polymerization, so there is no easy volatilization during curing. This method is superior in that it does not require the removal of sexual components, and therefore has the potential to produce products that are advantageous in terms of cost, and a new manufacturing method has been desired. The present inventors conducted extensive research in view of this point of view and found that a base material is impregnated with an unsaturated polyester resin liquid that is liquid at room temperature, then laminated, and air that inhibits radical polymerization is blocked. It has been discovered that a product with excellent properties can be manufactured by covering the product with a cover film or sheet and curing it for the purpose of ensuring surface smoothness.

Although this method has the feature of being able to perform continuous non-pressure molding, it has a drawback in the flatness of the product. As a result of further research, the present inventors discovered that by appropriately controlling the rigidity of this film or sheet material, it was possible to produce a product with excellent surface smoothness, and thus arrived at the present invention.

As described later, the term "surface smoothness" as used in the present invention refers to microscopic irregularities and gentle macroscopic irregularities resembling wave undulations that depend mainly on the surface properties of the base material. That is, the present invention impregnates a plurality of base materials that are continuously supplied in parallel with an unsaturated polyester resin liquid that is liquid at room temperature, laminates the resin-impregnated base materials, and then forms a film or sheet-like product. Flexural modulus of stiffness (E-K9/CTI)
When defined as the product of the cube of the thickness (Dcm), that is, E-D3k9・α, the . Rigidity value is 3 x 10-3 kg・G or more 3
A continuous electrical laminate characterized in that the laminate is continuously coated with a film or sheet material having a hardness of x101k9・σ or less and cured under substantially no pressure conditions. This is the manufacturing method.

The unsaturated polyester used in the present invention may be any well-known commercially available polyester, but one in which the mixture of the unsaturated polyester chain and the crosslinking comonomer is liquid at room temperature before curing is used.

In the present invention, it is more advantageous in terms of heat resistance and dimensional stability of the product to use an unsaturated polyester chain synthesized from propylene glycol, iso-phthalic acid and fumaric acid.

Styrene, α-methylstyrene, vinyltoluene, divinylbenzene, etc. are suitable as copolymerizable monomers, and it is preferable to use polyfunctional hydrocarbon monomers such as styrene and divinylbenzene together, or if necessary. If these materials are used in combination with a monofunctional derivative, the dimensional stability of the product is better. Further, in a preferred embodiment, the viscosity of the resin liquid at room temperature is 0.1 to 15 poise, more preferably 0.5 to 7 poise. This is to ensure the desired impregnation of the substrate. The base material as used in the present invention refers to a sheet-like base material such as paper such as linter paper or kraft paper, glass cloth, or nonwoven fabric made of inorganic and organic fibers.

In the present invention, a required number of resin-impregnated base materials are laminated, and a film or sheet-like covering/forced bar is further formed.

When covering these laminates and coatings, it is desirable to control the amount of resin required while removing excess resin liquid using a roll or blade-like object, but at this time, compressive force acts on the laminate. In addition, since the surface of the base material is generally not microscopically smooth, if a coating with low rigidity is used, the coating will follow the microscopic and macroscopic irregularities, and in the present invention, As described below, since it is cured under no pressure conditions,
There are cases where the surface quality of the product is not sufficient. According to the research of the present inventors, the rigidity value of a film or sheet-like material defined by E-D3k9・α is 3×10−3k9・α
When the above conditions were met, a practically preferable surface smoothness was obtained.

Furthermore, more desirable results are obtained when the stiffness value is 5X10-1k9·G or more. In the present invention, the stiffness value is 3
It is preferable to use a coating having a diameter of ×10 −3 k9·d or more and having flexibility, from the viewpoint of ensuring long objects and workability when peeling from the laminate. The present invention is achieved by covering both sides with such a coating and curing the resin liquid. For curing, organic peroxides are generally used as polymerization initiators, and the curing temperature is selected depending on the type of these and the combination of accelerators, but from the viewpoint of the pot life of the resin, etc. 60C~1500C
Preferably, the prescription will be such that:

Of course, in addition to thermal curing, curing by light, electron beam, radiation, etc. is also possible, and the present invention is not limited thereto. Further, during curing, in the present invention, a good product can be manufactured without requiring special pressure. On the contrary, unnecessary pressurization may cause the resin to flow out or cause distortion within the product, often resulting in unfavorable results in terms of dimensional stability and the like. Above, we have described electrical laminates with both sides covered with coatings.
In the present invention, a single-sided copper-clad laminate with excellent planar smoothness can be manufactured by using electrolytic copper foil on one side, for example.

Alternatively, by covering only one side of a resin liquid-impregnated laminate with the coating of the present invention and using another coating on the other side, it is possible to produce an electrical laminate with excellent surface smoothness on one side. In the present invention, one of the preferred embodiments is to use paper mainly composed of cellulose fibers as the base material.

The thickness is 200 to 300p and the basis weight is 150g/d.
Front and rear linter paper or kraft paper are suitable. These papers usually have microscopic irregularities as shown in Figure 1, and are coated with a rigidity value of less than 3 x 10-3 kg・α, such as a polyester film with a thickness of 35p (flexural modulus of 2). .8
1×10-4k9・d, so the stiffness value is 1.20
x10-3k9.d), the film follows the irregularities of the paper, resulting in a product with poor surface smoothness, as shown in FIG. The rigidity value of the coating is 3X10-3
When k9·α is exceeded, the ability to follow the unevenness of the base material is reduced. For example, when a polyester film with a rigidity value of 2.81 0-2k9·α and a thickness of 100p is used, as shown in FIG. 2, the following of the unevenness of the base material is slight. More preferably, a coating with a rigidity value of 5 x 10-1 kg/cm or more, for example, an aluminum foil with a thickness of 100 µm (the flexural modulus of this material is 0.67 x 1 Cfkg/d
1 Therefore, the stiffness value was 6.7 × 10-1 kg・α)
, or a stainless steel foil having a thickness of 100 μm (the bending elastic modulus of this material is 1.86×1 Cf'Kg·Clt, therefore, the rigidity value is 1.86 kg·T), etc. are suitable in the present invention. Further, the coating used in the present invention may be a single film or sheet-like material, or may be a composite film or sheet-like material.

In general, stiffness decreases as the temperature rises, but in the present invention, covering the laminate with the coating is usually possible at room temperature, so it is sufficient as long as the stiffness value at room temperature is within a predetermined range. It is not preferable that the stiffness value is significantly lowered.

Moreover, those having high adhesiveness to the cured unsaturated polyester resin are not preferred. From this point of view, cellophane, polyester, polypropylene, Teflon, polyamideimide films, etc. are suitable, and polyimide films are not suitable. Moreover, aluminum foil, rolled copper foil, and stainless steel foil are suitable. In this way, in the present invention, the coating can be easily peeled off without using a special release agent or release paper between the coating and the laminate, and there is no need to insert release paper or the like. be. If a film-like material is inserted for the purpose of mold release, etc., it is preferably a composite sheet-like material bonded to a coating. Furthermore, as can be easily inferred from FIG. 2, the surface of the product depends on the surface properties of the coating, so it is preferable that the surface of the coating be a mirror surface. Although the case where the base material is paper has been described above, the same can be said when other base materials are used.

In addition, by making the coating long, laminating resin-impregnated base materials that are continuously conveyed, and then continuously coating and curing the coating, we have created an electrical lamination with excellent surface smoothness. Plates can be manufactured continuously.

For this purpose, the stiffness value of the coating used must be 3 x 10-3k
It is preferable that it is 9.alpha. or more and has flexibility. Those with flexibility are in the form of a roll-like multilayer winding,
Alternatively, it can be handled in the form of an endless belt, greatly improving workability. From this point of view, the rigidity value of the coating is 3 x 10-3 k9・α ~ 3 x 101 kg・G
) are suitable for the present invention. According to the present invention, an electrical laminate with excellent surface smoothness and properties can be manufactured without requiring any pressure during continuous manufacturing.

In the present invention, pressurization during curing causes distortion in the base material and resin 5 due to compressive force, which is not preferable from the viewpoint of dimensional stability and the like. Therefore, the present invention is particularly advantageous in that it does not require a difficult process such as continuous pressurization. Also, O in electrical laminates and copper-clad laminates.
This requires advanced properties such as heat resistance, flame retardancy, dimensional stability under heating or moisture absorption, moisture absorption properties, punching workability, adhesive strength between the laminate and copper foil, and electrical insulation properties.

Therefore, various additives, mixtures, or fillers may be added to the unsaturated polyester resin liquid for the purpose of improving these, and this does not limit the present invention in any way. The present invention will be described in further detail with reference to Examples below. Example 1 Commercially available unsaturated polyester resin (Showa Kobunshi Rigolak 150HR, viscosity at 123°C: 5 poise) was added as a polymerization initiator to t-butylperoxy-2-
1 part by weight of ethylhexanoate and 0.6% cobalt naphthenate as a polymerization accelerator. ? Commercially available kraft paper (MKP-150, manufactured by Tomegawa Paper Industries) was continuously impregnated with the blended material, and two sheets of this resin-impregnated paper were passed between rolls to remove excess resin liquid and laminated together. Polyester film with a thickness of 100p (stiffness value 2.81
x10-2k9・CWL) on both sides, heated from 60°C to 100°C over 30 minutes, hardened, and further coated with 85°C x 1'3! f! After-curing was carried out under the conditions of 520p to obtain an electrical laminate having a thickness of 520p, excellent surface smoothness, and little surface waviness.

Moreover, this product was equivalent to NEMA standard XPC.
Comparative Example 1 In Example 1, the coating was a polyester film with a thickness of 3F3p (rigidity value 1.54 x 10-3 kg●C
In the case of m), the unevenness of the paper was reflected on the surface of the product, making it unsuitable for applications requiring surface smoothness.

Example 2 In Example 1, the coating was made of commercially available aluminum foil with a thickness of 100 μm (rigidity value 6.7×10 −1 kg·C!).
The sample marked n) showed excellent surface smoothness with little waviness.

The aluminum foil was easily peeled off. Example 3 In Example 1, the coated material was a commercially available stainless steel foil having a thickness of 100p (rigidity value: 1.86 k9·Cm), and exhibited excellent surface smoothness with little waviness.

The stainless steel foil was easily peeled off. In addition, the evaluation of the surface smoothness in Examples and Comparative Examples was based on visual observation and a surface roughness meter. As described above, the present invention enables the production of electrical laminates, which was difficult to manufacture continuously due to the conventional compression molding method using a press, to be able to manufacture electrical laminates continuously and in terms of quality, especially surface smoothness. This makes it possible to manufacture products comparable to compression molded products.

That is, since a press cannot be used in the continuous production method of rigid type laminates, for example, if a phenol resin, which generates water as a by-product during curing, is used, a cavity will be created inside the resin, making it impossible to obtain a completely satisfactory product.

Unsaturated polyester resins do not generate volatile by-products during curing and have excellent electrical properties, so they are suitable for the purpose of the present invention. Also, impregnating multiple base materials that are continuously supplied in parallel with resin liquid involves a series of subsequent steps in which the multiple base materials are laminated as they are after impregnation, and the laminate is coated and cured. It is convenient for the process to develop, and does not require manual handling during that time.

Furthermore, oxygen in the air is known to be a polymerization inhibitor for unsaturated polyester resins.

Therefore, during curing, the uncured laminate must be shielded from contact with air. If the stiffness value of the coating used for this purpose is not in an appropriate range, the coating will follow the unevenness of the surface of the laminate before curing because no press is used, and a laminate with excellent surface smoothness will not be obtained. The coating used in the method of the present invention also serves as a carrier sheet to prevent uncured resin liquid from adhering to and contaminating the curing device. By combining at least these requirements, the present invention enables the continuous industrial production of electrical laminates with quality, especially surface smoothness, that is comparable to conventional products made by shrinkage molding. This makes it possible to put it into practical use.

[Brief explanation of drawings]

FIGS. 1 and 2 are schematic diagrams showing the relationship between the unevenness of the base material and the coating. 1 is a coating, 2 is a resin-impregnated base material, and 3 is a resin layer.

Claims (1)

[Claims] 1. A plurality of base materials that are continuously supplied in parallel are impregnated with an unsaturated polyester resin liquid that is liquid at room temperature, and the resin-impregnated base materials are laminated to form a film or sheet. The stiffness of a shaped object is calculated by bending elastic modulus (E・kg/cm^2) and thickness (
dcm) to the third power, that is, E・d^3kg・cm, the rigidity value is 3×10^-^3kg・cm or more and 3×10^1kg・cm or less. A method for manufacturing an electrical laminate, characterized in that the laminate is continuously coated with a long coating and cured under substantially no pressure conditions. 2. The method for manufacturing an electrical laminate according to claim 1, wherein the base material is paper mainly composed of cellulose fibers. 3. The method for manufacturing an electrical laminate according to claim 1, wherein the surface of the film-like or sheet-like material is a mirror surface.