JPH0122149B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrical insulating laminate having a novel structure or a metal foil-clad laminate made of the same and metal foil. The object of the present invention is to provide an electrical laminate or a metal foil-clad laminate (hereinafter, both may be simply referred to as an electrical laminate) that has excellent insulation properties, dimensional stability, and heat resistance. In the present invention, the electrical insulating laminate refers to a laminate used as a substrate or support plate for various electronic components and devices, and the metal foil laminate is used for mounting electronic circuit components, etc. A printed circuit board that constitutes a printed circuit. Conventionally, these materials are made of phenolic resin, which is a thermosetting resin, and paper as a base material, or epoxy resin and paper, or epoxy resin and glass cloth, etc., and these resin varnishes are applied to the base material, such as paper or glass cloth. It is manufactured by impregnating the prepreg, then constructing a prepreg, and then laminating a large number of these sheets or a metal foil, such as an electrolytic copper foil, in a heated and pressurized press, and sufficiently curing the resin. ing. Conventional electrical laminates or metal foil laminates manufactured in this way are
For example, if one is made of phenolic resin and paper, it has a structure as shown in FIG. FIG. 3 shows a cross-sectional view of such a conventional laminate. That is, although paper composited with resin is laminated in multiple layers, the actual situation is that the paper fibers are essentially entangled between each layer, and the paper is not separated between each layer. On the other hand, it is well known that the electrical insulation properties, heat resistance, dimensional stability, etc. of electrical laminates are impaired due to moisture absorption or water absorption, which is undesirable from a practical standpoint. Water mainly enters the board through the surface layer of the laminate, but the presence of fibers in the base material such as paper and the presence of an interface layer between the fibers and resin make it easier for water to enter. For example, this applies to surfaces with exposed paper fibers in the surface layer, as shown in Figure 3; or adhesives for bonding metal foil to surfaces, or insulating plates, as shown in Figure 4. When measuring the surface insulation resistance of a surface on which a layer made of a resin equivalent to that of the previous one is measured under moisture absorption, the rate of decrease in the former case is extremely large. This means that the presence of paper fibers acts as a dominant factor in reducing resistivity and, therefore, infiltrating water into the surface layer and into the board. In such conventional products, for example, consider the case of the product represented in FIG. In such a state, water that has entered from the surface can easily penetrate into the interior through the continuous vertical fibers, which can be regarded as a substantially continuous structure. It is easy to absorb moisture and water,
In addition, the electrical insulation properties in such cases, especially JIS-
This causes a large decrease in the volume resistivity and insulation resistivity specified in C-6481, and further increases the moisture absorption value, which impairs heat resistance such as solder heat resistance. Foil-clad laminates have several drawbacks, such as an increase in the volume of the insulating plate portion, deterioration of dimensional stability, and increased warping of the board. In addition, although the conventional product represented by Fig. 4 is improved compared to the one shown in Fig. 3 as mentioned above, the resin layer that exists on the surface is slightly temporarily removed from the surface. This suppresses the intrusion of water and moisture, but once the moisture has penetrated into the board from the surface layer, it easily penetrates the inside of the laminate, and eventually results in considerable water absorption and deterioration due to moisture absorption. It turns out that there is no solution. In view of the current situation, the present inventor has already developed a structure in which heat is applied between each base material in order to eliminate the structure of conventional products in which each base material layer contacts each other and becomes a substantially continuous body when viewed in cross section. It was discovered that when a curable resin layer is formed to create a structure in which contact between each base material layer is substantially cut off, an electrical insulating laminate or metal foil-covered laminate with excellent properties can be obtained, and the patent application was filed in 1973. −11780 filed. As a result of further research, the inventor of the present invention found that the base material is paper mainly composed of cellulose fibers such as kraft paper, linter paper, or cotton paper, and the paper base material is a phenolic resin or amino resin having a methylol group. For example, when the thermosetting resin is an unsaturated polyester resin or an epoxy resin, it is pre-impregnated with a treatment agent whose main component is a dehydration condensation resin such as a phenolic resin, a melamine resin, or a urea resin. The present invention was achieved by discovering that an extremely high-performance electrical laminate or metal foil-clad laminate can be obtained. That is, the present invention provides a method for treating a paper base material mainly made of cellulose fibers, which has been treated with a treatment agent containing a methylol group-containing phenolic resin or an amino resin as a main component, with a thermosetting resin selected from unsaturated polyester resins or epoxy resins. In an electrical laminate made by laminating multiple sheets impregnated with a thermosetting resin, a layer of a thermosetting resin selected from an unsaturated polyester resin or an epoxy resin covers substantially the entire area of each base material layer. The content includes an electrical laminate formed continuously and alternately with base material layers. Various phenolic resins or amino resins having a methylol group can be used in the present invention, but methylolmelamine and/or methylolguanamine are preferred. Examples include initial condensates of guanamines such as guanamine and formaldehyde, or those obtained by etherifying part or all of their methylol groups with lower alcohols such as methanol and butanol. For the purpose of improving punching workability, it is preferable to mix or condense a higher aliphatic derivative in addition to the methylol group-containing phenolic resin or amino resin. Higher aliphatic derivatives include, for example, saturated fatty acids such as caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, and stearic acid; Saturated fatty acids and esters of the above fatty acids with polyhydric alcohols such as ethylene glycol, polyethylene glycol, propylene glycol, glycerin, pentaerythritol, sorbitol, aliphatic amides that are derivatives of the above fatty acids, and caprylic alcohol, lauryl alcohol , saturated or unsaturated higher alcohols such as myristyl alcohol, cetyl alcohol, stearyl alcohol, oleyl alcohol, linoleyl alcohol, ethers of higher alcohols and polyhydric alcohols, and aliphatic amines that are derivatives of higher alcohols. be able to. Also, oxyfatty acids and derivatives thereof such as ricinoleic acid can be used for the same purpose. in short,
Punching workability is achieved by having in the molecule a group that can condense with the methylol group of the amino resin, such as a hydroxyl group, carboxyl group, amino group, or amide group, and a long-chain alkyl group that acts to weaken the cohesive force of the amino resin. This is a necessary condition as a modifier. The number of higher aliphatic derivatives that meet these conditions is extremely large, but according to the results of studies conducted by the present inventors, when the number of carbon atoms is 8 or more, they can be used as punching processability modifiers. The effect becomes remarkable, and when using oleic acid, oleyl alcohol, and their derivatives, such as oleic acid monoglyceride, oleic acid diglyceride, oleic acid amide, and oleylamine, which have 18 carbon atoms and one unsaturated group, the resulting laminate It has also become clear that the performance of the present invention is well-balanced and good, and that this is a preferred embodiment of the present invention. By the way, the optimum amount of such a modifier to be used varies depending on the glass transition temperature of the unsaturated polyester resin used in the laminate, but it is usually a phenolic resin or an amino resin having a methylol group.
It is in the range of 3 to 40 copies per 100 copies. As for how to use it, either the modifier and the methylol group-containing phenolic resin or amino resin can be mixed in the form of a solution or suspension, or they can be used by condensing the two in advance. You can read it. In this case, water, alcohols, ketones, esters, etc. are used as the solvent. In the present invention, the paper whose main component is cellulose fibers that has been pre-impregnated with a treatment agent whose main component is a methylol resin-containing phenolic resin or an amino resin refers to the above-mentioned paper, for example, a dehydrated condensation resin A treatment agent whose main component is, for example, a solution dissolved in a solvent such as alcohol or water, which is impregnated into paper, and then the solvent is dried. However, impregnation treatment in which the weight ratio of the dehydrated condensation type resin attached to the paper after drying reaches 100%, as in the case of manufacturing so-called prepreg, is not preferred for the present invention. This is because such materials make it difficult to impregnate thermosetting resins such as unsaturated polyester resins and epoxy resins in the present invention, making it difficult to manufacture the products of the present invention. A preferable amount of adhesion is about 5 to 30%, more preferably about 10 to 20% based on the weight of the paper. The product of the present invention, in which the base material is paper that has been subjected to such impregnation treatment in advance, is an improvement of the above-mentioned invention by the present inventors, and it goes without saying that it exhibits better volume resistivity and insulation resistance. In addition to these, (1) It is possible to suppress the whitening phenomenon of the laminate due to the impact during punching. (2) The bending strength of the laminate is improved. (3) Volume resistivity, insulation resistance, and especially the induction characteristics when absorbing moisture are further improved compared to the case where the paper base material is not subjected to impregnation treatment in advance. From this point of view, in the present invention, it is preferable to use a paper base material that has been pre-impregnated with a treatment agent containing a melamine resin as a main component among dehydration condensation type resins. More preferable processing agents include methylolmelamine and/or methylolguanamine,
Furthermore, in addition to these, it is a mixture or condensation product with a higher aliphatic derivative having at least one group capable of condensing with a methylol group in the molecule. The above-mentioned higher aliphatic derivatives are useful for suppressing the occurrence of cracks during punching. As described above, the present invention is directed to a mixture of a dehydration condensation type resin such as a melamine resin as a main component and a third component for the purpose of improving punching processability, or a mixture of a dehydration condensation type resin and a third component, for example, for the purpose of improving punching processability. It includes a paper base material that has been previously impregnated with a treatment agent made of a reaction product with a component. It is essential in the present invention that the main component is a phenolic resin or an amino resin having a methylol group, and such a compound has a favorable affinity for both cellulose fibers and unsaturated polyester resins and epoxy resins. The present invention conjectures that this is connected to the above-mentioned improvement. The thermosetting resin used in the present invention can basically be any well-known unsaturated polyester resin or epoxy resin. However, it goes without saying that it is preferable to select a more appropriate grade depending on the use of the electrical laminate and the metal foil clad laminate. In the present invention, among these thermosetting resins, those that are liquid at room temperature and can be impregnated into a paper base material that has been impregnated in advance without being diluted with a solvent are particularly preferred. This is because the paper base material used in the present invention is pre-impregnated with, for example, dehydrated condensation resin, which adheres to or covers the surface of the cellulose fibers that are the main component. When impregnating with a resin diluted with a solvent, that is, a so-called resin varnish,
This is because, depending on the type of solvent used, an undesirable phenomenon may occur in which most of the dehydration condensation resin on the surface of the cellulose fibers is dissolved. First, the concept of the present invention is illustrated as a cross-sectional view of an insulating laminate.
As shown in Fig. and Fig. 2. In the electrical laminate of the present invention having the structure shown in the figure, water that has entered from the surface can be absorbed further into the interior by the resin layer that exists between the base material of the first layer and the base material of the second layer. The same thing can be said in sequence. Therefore, there is almost no intrusion of water into the interior of the laminate, and the aforementioned deterioration of properties due to moisture absorption and water absorption can be greatly improved. The thermosetting resin layer existing between the multiple base materials in the present invention may be constructed by any method. A more preferable method is selected depending on the processing conditions of the resin used. For example, it can be constructed by forming a prepreg by a well-known method, further applying a resin varnish to its surface, drying it again, and laminating and curing it in a press that is appropriately heated and pressurized. However, excessive pressurization at this time has the effect of trying to expel the resin present on each base material to the outside, making it difficult to form a resin layer between each base material. From this point of view, epoxy resins and unsaturated polyester resins that do not require large molding pressure and can be cured effectively even under substantially no pressure are preferred for the present invention. This is because the pressure can be selected with emphasis on controlling the thickness of the resin layer between each base material. These thermosetting resins contain a curing catalyst, a curing agent, a curing aid, and the like as usual. Further, the curing method is not limited to only heat curing, but may also be curing by radiation, light, or a combination thereof. A preferred embodiment of the method for manufacturing the electrical laminate according to the present invention is as follows. Using epoxy resins and unsaturated polyester resins that are liquid at room temperature in an uncured state,
A method such as impregnating an excessive amount of these resin liquids into a base material that has been previously treated with a treatment agent, or, if the amount of resin impregnated is small, further applying the resin liquid onto the base material when the base materials are stacked on top of each other. After passing through slits, each impregnated base material is laminated continuously or discontinuously by passing through slits with intervals calculated in advance from the thickness and number of base materials, or the thickness of the resin layer between base materials, etc. This can be achieved by heating and curing. When laminating and curing, use a cover sheet such as metal foil, cellophane, or plastic sheet on the side where metal foil is not laminated to improve surface properties or protect the resin that is affected by oxygen in the atmosphere during curing. can also be used as appropriate. This type of resin, which is liquid at room temperature in an uncured state, does not contain volatile components such as solvents, so it does not require drying. It is easy to control and is suitable for the present invention. Furthermore, in order to control the impregnation into the base material and the thickness of the resin layer between the base materials, the viscosity of the uncured resin liquid is also a factor;
Particularly suitable in the present invention is an unsaturated polyester resin that is liquid at room temperature and allows for easy preparation of a resin liquid in the range of 0.05 to 15 poise. The thickness of the resin layer between each base material constructed according to the present invention is usually preferably about 1 to 100 μm. If the thickness of this resin layer is excessively large, other properties such as punching properties may be impaired. The thickness of this resin layer is preferably equal to or less than the thickness of each base material used. In addition, to confirm the presence and thickness of this resin layer, either scrape the cross section with a sharp knife, or fix the specimen using resin for embedding the specimen, cut it, and lightly polish it. Accurate observation is possible using an optical microscope with a magnification of about 10 to 100 times using a well-known method. The metal foil used in the present invention is preferably aluminum foil or copper foil in terms of conductivity, mechanical strength, etc., and so-called electrolytic copper foil is particularly suitable due to its adhesive properties. In addition, in the present invention, in addition to the presence of a resin layer between each base material layer as shown in FIG. It goes without saying that it is preferable that a resin layer be present also on the bonding surface with the metal foil. At this time, the resin layer present on the surface to be bonded to the metal foil is preferably composed of an epoxy adhesive. For example, an epoxy adhesive consisting of a bisphenol A type epoxy resin and a polyamide resin curing agent is suitable. This is because such adhesives exhibit a desired cured product under no-pressure or low-pressure curing conditions, and if an adhesive that requires high pressure is used as a curing condition, the resin layer between each base material will deteriorate as described above. This is because it may have an adverse effect on the formation. As shown in Figures 1 and 2, it goes without saying that it is preferable that each base material layer is completely separated by a resin layer, but some parts of the base material may be separated from each other to some extent. The effects of the present invention can be achieved even if there is contact between the two. Further, the presence of the resin layer 3 on the surface shown in FIG. 2 is preferable in the present invention, but the present invention focuses on forming a resin layer between each base material layer, and the resin layer 3 on the surface is clearly formed. The present invention provides sufficient effects even in cases where this cannot be confirmed. In the present invention, when paper with a thickness of about 200 to 300 μm is used as a base material, for example, by laminating two to more than ten sheets, an electrical laminate with a thickness of about 0.5 to 3 mm or the thickness of these sheets can be obtained. It is possible to easily produce a metal foil-clad laminate having an insulating plate of. Hereinafter, the present invention will be explained in more detail with reference to Examples. Example A melamine resin consisting of 12 parts by weight of commercially available trimethylolmelamine (S-305 manufactured by Nippon Carbide), 1.6 parts by weight of oleic acid monoglyceride, 0.2 parts of a surfactant (Emulgen 905 manufactured by Kao Soap) and 100 parts by weight of water was used. Prepare an aqueous solution as a component, infiltrate commercially available kraft paper (MKP-150 manufactured by Tomegawa Paper Manufacturing Co., Ltd.) into the solution, pull it up, set the squeezing rate to 100%, and heat it at 100°C x 10
The paper base material was dried under the conditions of 10 minutes to obtain a paper base material which had been previously impregnated. Using 5 sheets of this paper base material, they were laminated and cured without pressure, and the thickness was approximately 1.5 mm, which was equivalent to that shown in Figure 1, that is, with a resin layer of approximately 15 μm between each paper base material and on the surface layer on both sides. A laminated insulating board was obtained. A commercially available unsaturated polyester resin (Polymer 6305, manufactured by Takeda Pharmaceutical Co., Ltd.) that is liquid at room temperature was used as the resin. As a curing catalyst, 1 part by weight of Perbutyl O (manufactured by NOF Corporation) was added in advance. The test results are shown in Table 1. Comparative Example 1 In the example, a laminated insulating board with a thickness of about 1.6 mm was obtained, which had almost no resin layer between each paper base material and on the surface layer on both sides. Comparative Example 2 In the example, a laminated insulating board having the same structure as the example was obtained using an untreated paper base material that had not been impregnated in advance. Comparative Example 3 A number of commercially available products having the structure shown in FIG. 3, manufactured from phenolic resin and paper base material, were tested. As a typical example from this
Comparative Example 3 was a commercially available product of XPC. As shown in Table 1, although this commercially available product test value is extremely reasonable for conventional products and is within the high performance range among conventional products, the laminate of the present invention is superior to conventional products. It has been clearly shown that it has extremely superior quality compared to 【table】

[Brief explanation of drawings]

FIG. 1 is a cross-sectional conceptual diagram of the electric laminate of the present invention;
FIG. 2 is a conceptual cross-sectional view of the metal foil-clad laminate of the present invention, and FIGS. 3 and 4 are conceptual cross-sectional views of conventional products. 1... Each sheet of paper base material impregnated with resin, 2...
...Resin layer existing between base materials, 3...Resin layer forming a surface layer, 4...Adhesive layer, 5...Metal foil.

Claims (1)

[Scope of Claims] 1. An electrical laminate including an insulating part made of a laminate of a plurality of base materials impregnated with a thermosetting resin selected from unsaturated polyester resin or epoxy resin, wherein the base material is A paper base material mainly made of cellulose fibers that has been treated in advance with a treatment agent containing a methylol group-containing phenolic resin or an amino resin as a main component, and that is continuous over substantially the entire area of each base material layer. An electrical laminate, characterized in that the thermosetting resin layers and base material layers are alternately formed. 2. The laminate according to claim 1, wherein the methylol group-containing resin in the treatment agent is a melamine resin. 3. The laminate according to claim 2, wherein the melamine resin is methylolmelamine or methylolguanamine. 4. The treatment agent is a mixture of (a) methylolmelamine or methylolguanamine and (b) a higher aliphatic derivative having at least one group capable of condensing with a methylol group in the molecule, or (a) and (b). The laminate according to claim 2, which is a reaction condensate of. 5. The laminate according to claim 1, 2, 3, or 4, wherein the thermosetting resin layer existing as a substantially continuous layer has a thickness in the range of 1 to 100 μm. 6. The laminate according to claim 1, which has a metal foil bonded to the outermost thermosetting resin surface with an epoxy resin adhesive. 7. Claims 1, 2, 3, 4, and 5, in which the resin present between the base material layers and the resin impregnated into the base material are the same type of thermosetting resin. Or the laminate according to item 6. 8. Mainly cellulosic fibers made by treating a thermosetting resin selected from unsaturated polyester resins or epoxy resins, which are liquid themselves at room temperature, with a treatment agent containing a methylol group-containing phenolic resin or an amino resin as a main component. A resin-impregnated base material is made by excessively impregnating a paper base material by impregnation and/or coating, and these are stacked on top of each other, and the thermosetting resin is continuous over substantially the entire area of each base material layer. 1. A method for manufacturing an electrical laminate, which comprises passing through slits having a predetermined interval so that layers of a synthetic resin are alternately formed with base material layers, and curing the slits. 9. The method for producing a laminate according to claim 8, wherein the resin having a methylol group in the treatment agent is a melamine resin. 10. The method for producing a laminate according to claim 9, wherein the melamine resin is methylolmelamine or methylolguanamine. 11 The treatment agent is a mixture of (a) methylolmelamine or methylolguanamine and (b) a higher aliphatic derivative having at least one group capable of condensing with a methylol group in the molecule, or (a) and (b). The method for producing a laminate according to claim 9, which is a reaction condensate of. 12. Production of a laminate according to claim 8, 9, 10 or 11, wherein the thermosetting resin layer existing as a substantially continuous layer has a thickness in the range of 1 to 100 μm. Method. 13. The method for manufacturing a laminate according to claim 8, which comprises laminating a metal foil onto the surface of the outermost thermosetting resin layer using an epoxy resin adhesive. 14. Claims 8, 9, 10, and 11, wherein the resin present between the base material layers and the resin impregnated into the base material are the same type of thermosetting resin.
The method for manufacturing a laminate according to item 12 or 13.