JP2006332578A - Printed wiring board and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printed wiring board with built-in parts which can be easily manufactured and scarcely leaves solvent and air bubbles in an insulating layer and is excellent in strength, and to provide a method of efficiently manufacturing the printed wiring board with built-in parts. <P>SOLUTION: In the printed wiring board in which parts are built, a part or all of the insulating layer constituting the printed wiring board consists of an insulating material including fiber which is not spun or woven and a resin composition, and relates to the method of manufacturing the printed wiring board. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a printed wiring board and a manufacturing method thereof.

  As seen in the example of integration of printed wiring boards used in the fields of personal computers and mobile phones in recent years, the density of component mounting has been increasing year by year. A general technique for increasing the density of component mounting is to increase the degree of integration of components mounted on a multilayer printed wiring board. The limit of density increase by this method can be easily estimated from the size and number of components to be mounted and the surface area of the printed wiring board on which they are mounted. On the other hand, there is a market demand for miniaturization and high performance of products, and it is necessary to mount a large amount of advanced components on a smaller board, which simply increases the degree of integration of components mounted on the surface of a printed wiring board. This approach is approaching its limits.

Therefore, in order to further increase the density, “component built-in substrates” in which components are also mounted inside the substrate have been actively studied. As a typical component built-in and multilayer method, holes are drilled in the board, such as embedding parts in through holes and vias, or mounting parts directly on the board and then embedding with prepreg or insulating resin A technique for forming a circuit has been devised. However, although these methods are effective methods, (I) the process of embedding with a resin or the like increases and becomes complicated. (II) When embedded with a resin alone, the strength tends to decrease. If embedded in, there is a possibility that the solvent may remain and cause defects, (IV) When prepreg is used, it is difficult to form a good insulating layer due to insufficient resin when embedding complicated mounting parts There is a need to establish a more effective manufacturing method.
JP 2004-96058 A JP 2004-319561 A JP 2003-92460 A JP 2002-344146 A JP 2002-76637 A JP 2001-298273 A JP 2001-298274 A Japanese Patent Laid-Open No. 2001-210955 Japanese Patent Laid-Open No. 10-56251 Japanese Patent Laid-Open No. 9-2104090

  In view of the above, the present invention can be easily manufactured, has a low possibility of leaving a solvent or air bubbles in the insulating layer, and has an excellent strength and a printed wiring board with a built-in component. The object is to provide a method of manufacturing well.

  That is, the present invention is characterized by the following items (1) to (4).

  (1) A printed wiring board having a built-in component, wherein a part or all of an insulating layer constituting the printed wiring board is made of an insulating material including unspun fibers and a resin composition. Printed wiring board.

  (2) The printed wiring board according to (1), wherein the fiber is glass fiber or aramid fiber.

  (3) A printed wiring board manufacturing method including a step of embedding a component mounted on a substrate with a sheet-like insulating material and forming an insulating layer, wherein the sheet-like insulating material is not woven and a resin composition A method for producing a printed wiring board comprising an insulating material containing

  (4) The method for producing a printed wiring board according to (3), wherein the fiber is glass fiber or aramid fiber.

  According to the present invention, a component-embedded printed wiring board that can be easily manufactured, has a low possibility of leaving a solvent or bubbles in an insulating layer, and has excellent strength, and efficiently manufactures the component-embedded printed wiring board. It becomes possible to provide a method.

  Hereinafter, embodiments of the present invention will be described in detail.

  The present invention is characterized in that a part or all of an insulating layer constituting a printed wiring board having a built-in component is an insulating layer made of an insulating material including a non-spun fiber and a resin composition. It is. The “component” in the present invention is a known component that can be mounted on a printed wiring board. For example, a passive element such as a capacitor, various capacitors, a chip coil, a semiconductor chip, a semiconductor element, or an active element is used. There are no particular restrictions on the type of elements. In addition, the printed circuit board is formed with necessary circuits, etc., and appropriate parts are mounted between the circuits, on the circuit, in the through holes, or in the vias, etc. Not limited. Preferably, the component is arranged around or inside the insulating layer made of the insulating material.

  The non-spun fibers may be either inorganic fibers or organic fibers, as long as they are not spun and do not significantly impair the properties of the printed wiring board while ensuring insulation. For example, glass, aramid, polyester, polyethylene, polypropylene, cellulose, acrylic, polyurethane, cupra, nylon, vinylon, polyacrylonitrile, rock wool, rayon, viscose, polyvinyl chloride, polyvinylidene chloride, polyacrylonitrile, polyclar , Silk, cotton, wool, hemp, and the like. The inorganic fiber is preferably a glass fiber, and the organic fiber is preferably an aramid fiber.

  The shape of the fiber is not particularly limited as long as it does not impair the properties of the printed wiring board, but the fiber diameter is preferably 3 to 13 μm. In addition, fibers having a diameter of several μm or less may be mixed alone or mixed with fibers having the above diameter range. Although it does not specifically limit about fiber length, Preferably, it is 6-15 mm.

  The resin composition is not particularly limited as long as it does not significantly impair the required characteristics as a printed wiring board, and is not particularly limited, but may be any resin composition mainly composed of a thermosetting resin or a thermoplastic resin. It is a resin composition mainly composed of a thermosetting resin. Although it does not specifically limit as a thermosetting resin, For example, an epoxy resin, a urea resin, a melamine resin, a phenol resin etc. can be mentioned preferably, Especially using an epoxy resin is especially preferable. These epoxy resins can be used alone or in combination.

  The epoxy resin is not particularly limited. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, biphenyl type epoxy resin, naphthalenediol type epoxy resin, phenol novolac type epoxy resin, cresol novolak Type epoxy resin, bisphenol A novolak type epoxy resin, cycloaliphatic epoxy resin, glycidyl ester resin, glycidyl amine resin, heterocyclic epoxy resin (triglycidyl isocyanurate, diglycidyl hydantoin, etc.) and these were modified with various materials Modified epoxy resins, brominated compounds thereof, halides such as chlorinated compounds, and the like can be mentioned, and two or more of these epoxy resins can be used in combination. In particular, the use of phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolak type epoxy resin or their halides is possible because the insulating layer can be provided with high heat resistance and reliability applicable to electrical and electronic materials. desirable. Although the addition amount of an epoxy resin is not specifically limited, In order to obtain sufficient hardened | cured material, it is preferable that it is the range of 1 to 95 weight% in all the resin compositions.

  Moreover, you may add a hardening | curing agent for the purpose of workability improvement, hardening acceleration of the added resin, etc. As the curing agent, for example, a known curing agent such as phenol, amine, cyanate, acid anhydride, or a compound having a dihydrobenzoxazine ring may be used alone or in combination. Specifically, phenolic novolak, cresol novolak, bisphenol A, bisphenol F, bisphenol S, phenolic curing agents having a phenolic hydroxyl group such as melamine-modified novolak type phenolic resins, or halides thereof, and amine curing agents such as dicyandiamide Etc.

  The compound having a dihydrobenzoxazine ring can be easily synthesized by heating and reacting phenols, amines and aldehydes in an appropriate solvent such as methyl ethyl ketone (MEK) and removing the solvent and water. . As the phenols, phenol, cresol, bisphenol A, bisphenol F, bisphenol S and the like can be used. As the amines, aniline, diaminobenzene and the like can be used. In the aldehydes, formaldehyde, paraform, etc. Can be used. Specifically, for example, 1 equivalent of aniline and 2 equivalents of formaldehyde are mixed with 1 equivalent of phenol to be used, refluxed and cooled at an arbitrary reaction rate, and then solvent and moisture. Depending on the case, a compound having a desired dihydrobenzoxazine ring can be obtained by removing unreacted substances.

  Moreover, when using an epoxy resin as resin in the said resin composition, what was made to react suitably with a hardening | curing agent beforehand can also be used.

  The addition amount of the curing agent is not particularly limited as long as it does not significantly inhibit the curing reaction of the resin composition, but is preferably added in the range of 0.5 to 80% by weight in the total resin composition.

  In addition to the above, an inorganic filler (filler) can be added to the resin composition in the present invention for the purpose of increasing the rigidity and reducing the thermal expansion. Can also be added. Examples of the inorganic filler include, but are not limited to, metal oxides such as molybdenum oxide, zinc oxide, and magnesium silicate, metal hydroxides such as aluminum hydroxide and magnesium hydroxide, alumina, silica, talc, mica, Calcium silicate, potassium silicate, calcined clay, titanium oxide, barium sulfate, strontium titanate, calcium titanate, barium titanate, aluminum oxide, magnesium carbonate, calcium carbonate, barium carbonate, in addition to molybdenum Further, it may be a compound such as an oxide composed of a plurality of elements such as zinc, calcium, phosphorus, aluminum, potassium, silicon, and magnesium.

  Furthermore, known pigments, adhesion assistants, antioxidants, curing accelerators, organic solvents, and the like can be added to the resin composition as long as the characteristics of the insulating layer in the present invention are not significantly impaired.

  The insulating material in the present invention is a material containing the non-spun fibers and the resin composition, and can be suitably used as an insulating layer of a printed wiring board containing components. The form of the insulating material may be pasty or sheet-like, and is not particularly limited. However, the insulating material is preferably in the form of a sheet and more preferably a resin-impregnated nonwoven fabric. In addition, the shape of the sheet-like insulating material is not particularly limited, and various shapes can be obtained by processing in advance.

  The resin-impregnated nonwoven fabric is not particularly limited, and for example, the fiber can be produced by making a paper to produce a nonwoven fabric, and the nonwoven fabric is impregnated with the varnish of the resin composition and dried. Alternatively, the fiber can be dispersed on a holding surface such as a wire mesh, impregnated with a varnish of the resin composition and dried, and then peeled off from the holding surface. The timing of peeling from the holding surface is not particularly limited, and may be before the resin composition varnish is impregnated, before the drying after the impregnation, or after the drying. In addition to the above, it can also be produced by dispersing fibers in a resin composition varnish and making paper. The resin content in the resin-impregnated nonwoven fabric is not particularly limited as long as a good insulating layer is formed, but is preferably 45 to 97% by weight, more preferably 75 to 97% by weight.

  The organic solvent used for preparing the resin composition varnish is not particularly limited as long as it has a viscosity and volatility suitable for uniformly dissolving or dispersing and impregnating the resin composition. However, methyl ethyl ketone, 2-methoxyethanol, 2-methoxypropanol, 1-methoxy-2-propanol, dimethylformamide (DMF), etc. are preferably used from the viewpoints of satisfying these requirements and price, handling, and safety. It is preferable to use about 5 to 75% by weight of the total weight of the resin composition.

  The method of forming the insulating layer with the insulating material is not particularly limited as long as the characteristics of the printed wiring board are not impaired. For example, the circuit is formed on or mounted on a substrate, components, vias, through holes, etc. A method of laminating a sheet-like insulating material such as the above resin-impregnated nonwoven fabric, pressing this with a metal foil or a release film and an end plate, and forming by heating and pressing is simple and easy, and the component is This is preferable because it can be embedded in the insulating layer. At this time, the number of sheet-like insulating materials to be stacked may be either one or a plurality, and is not particularly limited. Moreover, you may laminate | stack a prepreg, a resin sheet, copper foil with resin, etc. simultaneously with lamination | stacking of a sheet-like insulating material. For the purpose of improving workability after pressing, a release film such as a fluororesin film or polyethylene terephthalate may be used at the same time. Moreover, the conditions at the time of press molding are not particularly limited as long as the characteristics of the printed wiring board are ensured, but preferably 140 ° C. to 300 ° C., 200 hPa or less, 0.5 to 3 hours, more preferably 170 ° C. It is -250 degreeC and 40 hPa or less, and is 0.5 to 2 hours.

  In addition, the thickness of the insulating layer is not particularly limited as long as it does not impair the characteristics as a component built-in printed wiring board, and even if it is equivalent to a convex portion on a substrate, that is, a circuit or components, May be thicker or thinner. For example, as illustrated in FIG. 1B, the insulating layer 3 made of the resin-impregnated non-woven fabric may be formed so as to cover all the parts 1, and illustrated in FIGS. 1D and 1E. As such, the part 1 may be formed so as to be exposed. Furthermore, it is not necessary to embed a circuit or a component with only the insulating layer, and it may be supplemented with other constituent materials such as a prepreg, a resin film, or a copper foil with resin. 1A and 1C illustrate a state in which a prepreg, a resin film, and the like 2 are laminated on an insulating layer 3 made of the resin-impregnated nonwoven fabric. In FIG. 1, the circuit 5 formed on the insulating layer 4 is entirely embedded with the insulating layer 3, but part or all of the circuit is made of an insulating material different from the insulating layer made of the resin-impregnated nonwoven fabric. It may be embedded with other insulating layers. Although not shown, the insulating layer 3 made of the resin-impregnated nonwoven fabric may be formed on both sides of the insulating layer 4.

  In addition, uneven portions between circuits or parts of printed wiring boards, or concave portions such as through-holes and vias are filled with resin of the above sheet-like insulating material even if they are filled with resin, conductive paste or the like in advance. And it can be filled.

  In addition, part or all of the resin-impregnated nonwoven fabric and part or all of the fibers in the resin may be cut or broken during molding, but there are particular restrictions unless the characteristics of the printed wiring board with built-in parts are significantly impaired. Is not to be done.

  In the above, the insulating layer made of the resin-impregnated nonwoven fabric, which is the main feature of the present invention, has been mainly described. However, when the component-embedded printed wiring board of the present invention is manufactured, in addition to the above, the manufacture of the printed wiring board Needless to say, materials and processes known in the art may be applied.

  Hereinafter, the present invention will be described more specifically with reference to examples of the present invention and comparative examples thereof, but the present invention is not limited to these examples.

  In the examples and comparative examples, the following were used as epoxy resins, curing agents, prepregs, and the like. Nonwoven fabric is glass nonwoven fabric (product name: EPM-4025BH, manufactured by Japan Vilene, fiber diameter: average fiber diameter (diameter) 10 μm, fiber length: average fiber length 13 mm) and aramid nonwoven fabric (product name: APTF22, Oji) Made by Paper Manufacturing Co., Ltd., Sales: DuPont Teijin Advanced Paper Co., Ltd., fiber diameter: 8 μm (0.75 denier)) was used. For other organic solvents, additives, general-purpose fillers, non-woven fabrics, copper foils, releasable films, etc., raw materials generally used in the chemical industry and the electronics industry were used except those specifically described.

Epoxy resin: Cresol novolak type epoxy resin (trade name N-673 (epoxy equivalent 210)) manufactured by Dainippon Ink and Chemicals, Inc.
Phenol-based curing agent A: Melamine novolak resin (trade name Phenolite LA-7054) manufactured by Dainippon Ink and Chemicals, Inc.
・ Prepreg: Glass cloth prepreg manufactured by Hitachi Chemical Co., Ltd. (trade name: GEA-67BE HAHJ (corresponding to an insulating layer thickness of 100 μm))
Copper-clad laminate: manufactured by Hitachi Chemical Co., Ltd. (trade name: MCL-E-67 35D t0.4mm)
Test pattern: A copper-clad laminate of 250 mm square was etched in stripes with a width of 100 μm and an interval of 100 μm (line space 100 μm / 100 μm) by a subtractive method to form a pseudo circuit. On this substrate, a metal piece having a width of 1 mm, a length of 2 mm, and a thickness of 1 mm that was regarded as a component was bonded to form a through hole having a diameter of 1.0 mm. The arrangement of the metal pieces and the through-holes was set to 400 in total, 20 vertically and 20 horizontally at intervals of 5 mm on the substrate. The metal piece was bonded to both sides.

Example 1
The epoxy resin and the curing agent were weighed so that the equivalent ratio of epoxy group and hydroxyl group was 1: 0.8, and dissolved in methyl ethyl ketone so as to have a solid content concentration of 75% by weight. Furthermore, the hardening accelerator and the additive for viscosity adjustment were added, and the varnish was produced. This varnish was impregnated into a glass nonwoven fabric and dried at 160 to 175 ° C. for 4 minutes to obtain a resin-impregnated nonwoven fabric (corresponding to 100 microns) having a resin content of 86% by weight.

  Evaluation is made by laminating the resin impregnated non-woven fabric 7Ply and the prepreg 1Ply produced on both sides of the test pattern, respectively, and further superposing copper foil on the outside, with a vacuum degree of 40 hPa, a hot plate temperature of 185 ° C. and a product pressure of 3 MPa. For 80 minutes to prepare an evaluation substrate. And evaluation of the moldability, heat resistance, and impact test of this evaluation substrate was performed as follows. The evaluation results are shown in Table 1.

  Formability was determined by visual inspection after the copper foil on both sides of the evaluation substrate was entirely removed by etching. Furthermore, the circuit, components (metal pieces), and through-hole portions were taken out, and after casting with epoxy resin, the cross section was confirmed with a microscope to confirm that there were no voids.

  For heat resistance, the evaluation substrate was cut into 50 mm square and dried, and then immersed in 260 ° C. solder for 10 seconds to check for abnormalities such as blistering.

  The impact test was a falling ball test. In the falling ball test, a spherical weight of 50 g was dropped on the evaluation substrate, and the drop height when a crack occurred on the substrate was measured, and the case where the height was 50 cm or more was regarded as acceptable (no problem).

(Example 2)
An evaluation substrate was prepared in the same manner as in Example 1 except that the glass nonwoven fabric was changed to an aramid nonwoven fabric, and the same evaluation was performed. The evaluation results are shown in Table 1.

(Comparative Example 1)
An evaluation substrate was prepared in the same manner as in Example 1 except that the prepreg 8Ply was laminated on both sides of the test pattern, and the same evaluation was performed. The evaluation results are shown in Table 1.

(Comparative Example 2)
A release film is laid on a glass substrate so that the release surface is on top, and the same varnish as in Example 1 is applied in several portions, air-dried, and when the resin thickness reaches 200 μm, 160 The resin sheet with a carrier film was obtained by drying at ~ 175 ° C for 4 minutes and removing the release film together with the glass substrate. Next, four sheets of this resin sheet were laminated on both sides of the test pattern while peeling off the carrier film, and then a prepreg was further laminated, and copper foil was further laminated on the outside, and the degree of vacuum was 40 hPa and the hot plate temperature was 185. An evaluation substrate was produced by heating and pressing at 80 ° C. and a product pressure of 3 MPa for 80 minutes, and the evaluation substrate was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

(Comparative Example 3)
The same varnish as in Example 1 was directly applied to both sides of the test pattern and dried to try to form an insulating layer between the parts. The results are shown in Table 1.

  From Table 1, in Examples 1-2, the test results were all “good” or “no problem”. The handleability of the resin-impregnated non-woven fabric was as good as that of the prepreg, and the peripheral portions of the circuits and components were sufficiently filled with fibers and the resin composition, and the vias and through holes were also filled with the resin. In addition, no defects were found in the moldability evaluation by visual observation and microscopic observation. Furthermore, the heat resistance and impact test characteristics were also good. However, in Comparative Examples 1 to 3, various problems occurred and the characteristics as a printed wiring board were impaired.

  From the above, it can be said that an insulating layer made of an insulating material containing unspun fibers and a resin composition has good characteristics as an insulating layer of a printed wiring board containing components. It can be said that the component built-in printed wiring board having an insulating layer is superior in various characteristics to the component built-in printed wiring board manufactured by the conventional method. Therefore, the superiority of the present invention is clear.

Sectional drawing of one Embodiment of the component built-in printed wiring board of this invention.

Explanation of symbols

1: Component 2: Prepreg, resin film, etc. 3: Insulating layer 4 made of resin-impregnated nonwoven fabric of the present invention 4: Insulating layer 5: Circuit

Claims (4)

  A printed wiring board having a built-in component, wherein a part or all of an insulating layer constituting the printed wiring board is made of an insulating material containing unspun fibers and a resin composition Board.   The printed wiring board according to claim 1, wherein the fibers are glass fibers or aramid fibers.   A printed wiring board manufacturing method including a step of embedding a component mounted on a substrate with a sheet-like insulating material and forming an insulating layer, wherein the sheet-like insulating material includes an unwoven fiber and a resin composition. A method for producing a printed wiring board comprising a material.   The method for producing a printed wiring board according to claim 3, wherein the fibers are glass fibers or aramid fibers.

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