KR100726249B1 - Prepreg and copper clad laminate comprising inorganic reinforcement having honeycomb structure - Google Patents

Abstract

A prepreg, a copper clad laminate, and a method of manufacturing the same, which include an inorganic reinforcement having a three-dimensional structure, which is light in weight, has a low dielectric constant, and can reduce the problem of warpage, has been proposed. According to an aspect of the present invention provides a copper clad laminate comprising an inorganic reinforcing material having a honeycomb structure connected not only in the horizontal direction but also in the vertical direction.

Prepreg, copper clad laminate, inorganic reinforcement, honeycomb

Description

Prepreg and copper clad laminate comprising inorganic reinforcement having honeycomb structure}

1 is a view showing a cross-sectional structure of a conventional copper clad laminate,

2 is a view showing a cross-sectional structure of a copper clad laminate according to an embodiment of the present invention,

3 is an enlarged (× 10,000) photograph of a polymer colloidal crystal according to one embodiment of the present invention observed through a SEM,

4 is an enlarged (× 10,000) photograph of an inorganic reinforcing material observed through an SEM according to an embodiment of the present invention;

5 is a schematic diagram showing a process of manufacturing a copper clad laminate according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

1: copper foil

2, 4: glass fabric

3: resin

5: mixed layer of inorganic reinforcing material and resin

6: inorganic reinforcement with honeycomb structure

The present invention relates to prepregs and copper clad laminates that can be used for substrate manufacture.

Recently, electronic devices tend to become smaller, thinner, and lighter, and printed circuit boards used for them are also required to have a thinner thickness. However, when a printed circuit board is processed using a thin material, a large amount of defects such as twisting or bending of the substrate may occur due to handling problems during processing or device problems in the processing process, resulting in a decrease in product yield. In addition, as printed circuit boards using halogen-free halogen-free, lead-free solder, etc., which are environmentally harmless, are required, thermal effects on substrate materials are increased due to higher processing temperatures. This warpage is more problematic in flip-chip printed circuit boards, due to the difference in thermal expansion caused by the relatively large bumps. The core is used to prevent warpage.

However, in order to improve the electrical characteristics, it is expected that thin materials will be gradually used in the future, and it is essential to find a way to eliminate the occurrence of warpage. As a method of improving this problem, a method of using a ceramic substrate close to thermal expansion of a semiconductor chip and having a high modulus of elasticity has been proposed. However, this method increases manufacturing costs, increases the weight of the substrate, and makes it difficult to form high-density wiring. Has its drawbacks. In addition, a multilayer printed circuit board using a wholly aromatic polyamide fiber cloth as an organic substrate has been proposed, but problems of warping and warping of the substrate still exist.

The present invention provides a prepreg and a copper clad laminate, and a method for manufacturing the copper clad laminate, which include an inorganic reinforcing material having a honeycomb structure that is light in weight, has a low dielectric constant, and can reduce the problem of warping.

According to an aspect of the present invention, it is possible to provide a prepreg and a copper foil laminated plate including an inorganic reinforcing material having a honeycomb structure and a resin.

In addition, according to another aspect of the present invention, it is possible to provide a substrate comprising a prepreg or a copper-clad laminate comprising the inorganic reinforcing material and the resin of the honeycomb structure.

In addition, according to another aspect of the present invention, it is possible to present a method for producing a copper clad laminate comprising the step of forming an inorganic reinforcing material having the honeycomb structure.

Hereinafter, this will be described in detail according to a preferred embodiment. However, prior to detailed description, the cause and the solution of the warpage of the substrate will be described first.

It is known that the main cause of the warpage of the substrate is due to thermal stress due to the difference in thermal expansion rate between the substrate material and the chip. There are two ways to solve this problem. First, there is a method of using a material stronger than glass fiber, that is, a material having a high modulus of elasticity, as a reinforcing material to withstand the stress generated. There is a method to use similar materials as the core material so as not to generate thermal stress itself which causes bending.

Materials with higher modulus of elasticity and lower coefficient of thermal expansion than glass fiber include various metal materials, inorganic materials, and reinforcing fibers. However, metal materials have no electrical insulation properties, which makes the process complicated and increases the process cost. have. In addition, ceramic materials have high applicability in mechanical and electrical properties, but have disadvantages of increased weight and high dielectric constant when manufacturing a substrate.

The present invention seeks to solve the above problems caused when the ceramic material is used as a substrate material and to propose a new substrate material which can maintain the advantages of the ceramic material. The use of a woven ceramic material in the form of a fiber is excellent in thermal expansion characteristics in the plane, as in the case of using a glass fiber reinforcement, but has no reinforcing effect in the vertical direction, it has been shown to have no significant effect in improving the bending property.

Accordingly, in the present invention, the bending property of the substrate is improved by using an inorganic reinforcing material having a three-dimensional honeycomb structure in which the reinforcing materials are connected to each other not only in the horizontal direction but also in the vertical direction while maintaining the thermal expansion rate similar to that of the chip.

1, 2 and 5, in the prepreg and the copper-clad laminate according to an embodiment of the present invention, the inorganic reinforcing material 6 is three-dimensionally connected, and the internal space is made of resin 3. Compared to the use of a flat plate-type inorganic material, it is relatively light in weight and can impregnate more than 50% of resin, and thus has an advantage of maintaining a low dielectric constant.

In the present invention, in order to introduce a three-dimensional structure connected in the vertical and horizontal directions to the inorganic reinforcing material, a honeycomb structure was formed.

The honeycomb structure means a shape in which a plurality of cells, which are partitioned by a plurality of gratings and serving as a fluid flow path, is formed, that is, a porous structure partitioned by a plurality of gratings. Therefore, the overall shape of the honeycomb molded body is not particularly limited as long as it has a porous structure partitioned into a plurality of lattice, and may include shapes such as cylindrical, square pillars, triangular pillars and the like. The honeycomb molded body's cell shape (cell shape in the vertical section with respect to the cell formation direction) is not particularly limited, and may include shapes such as rectangular cells and triangle cells in addition to the hexagonal cells of FIG. 4. In addition, the molding method of the three-dimensional structure including a honeycomb structure may be a molding method known to those skilled in the art, such as extrusion molding, injection molding, press molding. The drying method is not particularly limited, and conventional drying methods such as hot air drying, microwave drying, dielectric drying, reduced pressure drying, vacuum drying and freeze drying can be used.

In a preferred embodiment of the present invention, a colloidal crystal template method was used to mold the honeycomb structure.

According to this method, first, spherical monodisperse polymer particles having a uniform diameter are synthesized. These monodisperse polymer particles can be easily synthesized through general emulsion polymerization or emulsifier-free emulsion polymerization without using an emulsifier, and polymer particles having a particle size of 200 nm to 800 nm as the reaction conditions are controlled. Can be synthesized while maintaining a constant degree of dispersion. Generally, polystyrene is most commonly used as a polymer, but in addition, vinyl acetate, butyl acrylate, butyl methacrylate, vinyl propionate, and vinyl Can be used by polymerizing free-radical polymerizable molecules such as cyclopropene, acrylamide, vinylylidene chloride, and vinyl pridine methacrylate. have. In order to form a more uniform arrangement when the synthesized monodisperse polymer particles are crystallized, ionic groups may be introduced to the surface of the polymer particles. In one preferred embodiment of the present invention, sulfonic acid (-SO ₃ H) groups are introduced to the polystyrene particle surface.

Then, according to a preferred embodiment of the present invention, the synthesized uniform diameter polymer particles are arranged as shown in Figure 3 by filtration to form a colloidal crystal. Such an arrangement may be formed by a self-arrangement phenomenon by allowing the polymer particles dispersed in the liquid phase to sink to the bottom by gravity. For faster alignment, driving forces such as filtration and centrifugation can be applied. Subsequently, after the polymer particles are completely dried, the precursor of the inorganic material is introduced into the space between the polymer particles in a liquid form. The liquid inorganic material precursor can be easily introduced into the nano-sized space between the polymer particles by capillary action.

As the inorganic material, silica (SiO ₂ ), alumina (Al ₂ O ₃ ), silicon nitride (Si ₃ N ₄ ), aluminum nitride (AlN), or the like may be used. In a preferred embodiment of the present invention, Tetra ethyl ortho silicate (TEOS) was used as a precursor of silica, and after drying the structure in which the inorganic material was introduced between the polystyrene polymer particles, the polymer particles were burned in a high-temperature firing furnace and Firing the precursor yields an inorganic reinforcement with a honeycomb structure similar to the honeycomb shape of FIG. 4.

The inorganic reinforcing material obtained by the above method can be used for the production of an insulating material for prepreg or substrate manufacture by impregnating and drying the resin in the same manner as other reinforcing materials.

In addition, a copper foil laminated sheet may be manufactured by coating copper foil on a resin-impregnated inorganic reinforcing material by a known method or by laminating a copper foil coated with resin on an inorganic reinforcing material. In a preferred embodiment of the present invention, the B-stage Resin coated copper (RCC) was laminated on the upper and lower layers of the inorganic reinforcing material and molded under vacuum to obtain a double-sided copper clad laminate.

The resin used for the production of the prepreg and the copper clad laminate is not particularly limited and may be one commonly known. For example, an epoxy resin, a cyanic acid ester resin, a bismaleimide resin, a polyimide resin, a modified polyphenylene ether resin, etc. are mentioned, These resin can be used individually or in mixture of 2 or more types. In addition, bromine is added to the above-mentioned resins, and flame retardant resins can also be used. In general, the resin constituting the insulating layer of a copper clad laminate or a printed circuit board is rarely used as a single material, and is suitably used in consideration of desired physical properties and price. Moreover, various additives can be mixed in the range which does not greatly affect the characteristic of these thermosetting resin compositions. For example, various additives such as thermosetting resins, thermoplastic resins, inorganics, organic fillers, dyes, thickeners, lubricants, defoamers, dispersants, leveling agents, brighteners, and polymerization initiators other than the above-mentioned thermosetting resin compositions may be used depending on the desired purpose or use. Can be added. Moreover, as a flame retardant, phosphorus, a flame-retardant compound, bromine-free, etc. can be used, for example. Moreover, this flame retardant can use all the functional groups which exist or do not exist in a molecule | numerator. The resin composition may be cured by heating the resin itself, but may further include a suitable amount of a known curing agent and a thermosetting catalyst because the curing rate is slow and productivity is poor.

In addition, according to another aspect of the present invention, it is possible to provide a substrate including a prepreg or a copper clad laminate having an inorganic reinforcing material of a honeycomb structure. In other words, by applying the prepreg and the copper-clad laminate, it is possible to manufacture a printed circuit board or a semiconductor chip mounting substrate by laminating in various layers as required.

In addition, according to another aspect of the present invention, it is possible to present a method for manufacturing a copper clad laminate comprising the step of forming an inorganic reinforcing material having a honeycomb structure.

Specifically, the manufacturing method of the copper-clad laminate,

1) forming an inorganic reinforcement having a honeycomb structure; And

2) forming a copper foil layer coated with a resin on the upper layer and the lower layer of the inorganic reinforcing material, or

1) forming an inorganic reinforcement having a honeycomb structure;

2) forming a resin layer on the upper layer and the lower layer of the inorganic reinforcing material; And

3) forming a copper foil layer on the outer layer of the resin layer.

Here, the step of forming the inorganic reinforcing material of step 1) is not particularly limited as long as it is a method capable of forming a honeycomb structure, preferably by the colloidal crystal template method described above.

In addition, step 2) can be achieved by those who are skilled in the art by predictable conditions and methods, and is not particularly limited, but generally at a temperature of 100 to 300 ° C. and a pressure of 5 to 50 kgf / cm 2, Preferably it can be achieved by lamination for 30 minutes to 3 hours under vacuum.

Hereinafter, the present invention will be described in detail by way of examples, but the spirit of the present invention is not limited to the above embodiments, and many modifications are possible by those skilled in the art within the spirit of the present invention.

Example 1 Preparation of Inorganic Reinforcement with Honeycomb Structure

Inorganic reinforcement having a three-dimensional honeycomb structure was formed by the colloidal crystal templating method.

First, spherical polystyrene particles having a uniform diameter of about 200 nm to 800 nm were synthesized through an emulsion polymerization method. In order to form a more uniform arrangement when crystallizing monodisperse polymer particles, sulfonic acid (-SO ₃ H) groups were introduced to the surface of polystyrene. Polystyrene particles of uniform diameter were prepared by filtration to form colloidal crystals, and the polystyrene particles were completely dried. Then, the precursor TEOS (Tetra ethyl ortho silicate) of the inorganic material was penetrated into the space between the polystyrene particles in liquid form. . After drying completely, the polystyrene particles were burned at 600 ° C. for 5 hours and the TEOS was calcined to obtain an inorganic reinforcing material having a three-dimensional structure.

Example 2 Preparation of Prepreg Including Inorganic Reinforcement of Honeycomb Structure

450 parts by weight of the resin composition 2,2, -bis (4-cyanatephenyl) propane monomer was melted at 160 ° C. and reacted for 4.5 hours while stirring to obtain a mixture of the monomer and the prepolymer. This was melt | dissolved in methyl ethyl ketone, and 300 weight part of bisphenol-A epoxy resins, 100 weight part of phenol novolak-type epoxy resins, and 150 weight part of cresol novolak-type epoxy resins were mix | blended with this. 1000 weight part of calcined talc was added here, zinc octylate was melt | dissolved in 0.2 weight part of methyl ethyl ketone, and added as a hardening catalyst, and the compound obtained by well stirring was made into the varnish.

The varnish was impregnated into the inorganic reinforcing material of Example 1, dried, and the prepreg was produced so that the thickness after shaping | molding might be 100 micrometers.

Example 3 Preparation of Copper Clad Laminates Including Inorganic Reinforcement of Honeycomb Structure 1

Resin coated copper (RCC) having a thickness of 12 μm was laminated on the upper layer and the lower layer of the inorganic reinforcing material prepared in Example 1, and then molded for 2 hours under vacuum at 250 ° C. and 5 mmHg, and the insulating layer thickness was 200 μm. Phosphor double-sided copper clad laminate was prepared.

Example 4 Preparation of Copper Clad Laminates Including Inorganic Reinforcement of Honeycomb Structure 2

An electrolytic copper foil having a thickness of 12 μm was placed on both outer sides of the prepreg prepared in Example 2, and laminated by molding for 2 hours under vacuum at 250 ° C. and 5 mmHg to prepare a double-sided copper foil laminated plate having an insulating layer thickness of 200 μm.

Comparative Example 1: Fabrication of Copper Clad Laminate with Horizontal Reinforcement

The varnish of Example 2 was impregnated and dried by the glass woven fabric of thickness 0.093mm, and the resin amount was made to adhere so that the thickness after shaping | molding may be 100 micrometers, and the prepreg was produced. After stacking the two prepregs, the electrolytic copper foil having a thickness of 12 μm was placed on the upper layer and the lower layer, followed by lamination molding under vacuum at 250 ° C. and 5 mmHg for 2 hours to prepare a double-sided copper foil laminated plate having an insulating layer thickness of 200 μm.

Experimental Example 1: Efficiency Measurement of Copper Clad Laminates

1-1: permittivity measurement

It measured according to the method of IPC-650 2.5.5.3 with the structure of Example 2-Example 4 and the comparative example 1.

1-2: Warping and twisting (elastic modulus) measurement

In the structure of each Example and a comparative example, without using copper foil, it laminated | stacked similarly and produced the laminated board, measured by DMA method, and measured the elasticity modulus at 260 degreeC.

Example 1 Example 2 Comparative Example 1 Permittivity (1MHz) 5.0 4.9 4.6 Modulus of elasticity (GPa) 39 38 26

From the above results, it was confirmed that the copper-clad laminate including the inorganic reinforcing material having the honeycomb structure of the present invention can lower the dielectric constant and reduce the warpage or distortion of the substrate.

As described above, the prepreg and copper-clad laminate including the inorganic reinforcing material having the three-dimensional structure according to the present invention is light in weight, has a low dielectric constant, and can reduce the problems of warpage or warping, which is useful for miniaturization and weight reduction of electronic devices. Can be used as substrate material.

Claims (13)

A prepreg comprising an inorganic reinforcement and a resin having a honeycomb structure. The method of claim 1, wherein the inorganic reinforcing material is at least one selected from the group consisting of silica (SiO ₂ ), alumina (Al ₂ O ₃ ), silicon nitride (Si ₃ N ₄ ), and aluminum nitride (AlN). Prepreg obtained from a precursor. The prepreg of claim 1, wherein the resin is at least one resin selected from the group consisting of epoxy resins, cyanic acid ester resins, bismaleimide resins, polyimide resins, and modified polyphenylene ether resins. Copper foil laminated board containing inorganic reinforcement material and resin which have honeycomb structure. The method of claim 4, wherein the inorganic reinforcing material is at least one selected from the group consisting of silica (SiO ₂ ), alumina (Al ₂ O ₃ ), silicon nitride (Si ₃ N ₄ ) and aluminum nitride (AlN). The copper clad laminated board obtained from a precursor. The copper-clad laminate of claim 4, wherein the resin is at least one resin selected from the group consisting of an epoxy resin, a cyanic acid ester resin, a bismaleimide resin, a polyimide resin, and a modified polyphenylene ether resin. A substrate comprising the prepreg of claim 1 or the copper-clad laminate of claim 4.  The substrate of claim 7, wherein the substrate is a printed circuit board or a semiconductor chip mounting substrate.  1) forming an inorganic reinforcement having a honeycomb structure; And 2) A method of manufacturing a copper-clad laminate comprising a step of forming a resin-coated copper foil layer on the upper layer and the lower layer of the inorganic reinforcing material. 1) forming an inorganic reinforcement having a honeycomb structure; 2) forming a resin layer on the upper layer and the lower layer of the inorganic reinforcing material; And 3) A method for producing a copper clad laminate comprising the step of forming a copper foil layer on the outer layer of the resin layer. The method of claim 9 or 10, wherein the inorganic reinforcing material is selected from the group consisting of silica (SiO ₂ ), alumina (Al ₂ O ₃ ), silicon nitride (Si ₃ N ₄ ) and aluminum nitride (AlN). A method for producing a copper clad laminate obtained from at least one precursor. The copper clad laminate according to claim 9 or 10, wherein the resin is at least one resin selected from the group consisting of an epoxy resin, a cyanic acid ester resin, a bismaleimide resin, a polyimide resin, and a modified polyphenylene ether resin. Manufacturing method. The method for producing a copper clad laminate according to claim 9 or 10, wherein the inorganic reinforcing material is formed by a colloidal crystal template method.

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