JP2006004854A - Patterned dielectric composition and method for forming the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dielectric composition and an optical wiring material thin enough as an interlayer insulation material for a large electrostatic capacitance capacitor contained in a high density SiP, in which the dielectric composition is patterned with an arbitrary shape in an arbitrary place on a substrate without losing the dielectric constant of the dieclectric composition itself. <P>SOLUTION: The dielectric composition comprises a resin, and an inorganic filler at least a part of which is dissolved in an developer. The quantity of the inorganic filler contained in the dielectric composition is not less than 60 volume% for the total amount of the solid material in the composition. The taper angle of the cross section of the patterned film formed by developing the film dielectric composition is not less than 70° and not larger than 110°. The pattern is formed by dissolving the filler component in the dielectric composition by using a mixed solution containing acid and hydrogen peroxide. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a dielectric composition exhibiting characteristics suitable as a capacitor or an interlayer insulating material for a circuit material having a function as a capacitor or an optical wiring material.

  In recent years, with the demand for downsizing electronic devices, increasing the speed of signals, and increasing the capacity, the density of mounted circuit components has been increasing. However, electrical noise increases and data errors are becoming a problem. In order to suppress the generation of this electrical noise and to operate the semiconductor device stably, it is important to supply a necessary amount of current from a position close to the semiconductor device. For this purpose, it is effective to dispose a capacitor having a large capacity directly under the semiconductor device as a decoupling capacitor.

  Therefore, as a method of arranging a capacitor on the printed wiring board, there is a method of arranging an external capacitor such as a chip capacitor on the printed wiring board. However, from the viewpoint of miniaturization, it is advantageous to add an inorganic filler to the inner layer of the printed wiring board to give the printed wiring board itself a capacitor function, and a composite of inorganic filler and resin is used as an interlayer insulating material. A method (see Patent Documents 1 and 2) is known. The composite containing an inorganic filler by the above method can increase the relative dielectric constant by increasing the addition rate of the inorganic filler.

  As a method for disposing a capacitor at an arbitrary place on a printed wiring board, there is a process using a photolithography technique, and a photosensitive paste in which inorganic fine particles are filled in a photosensitive resin has already been developed (see Patent Document 3). However, an acrylic copolymer with low heat resistance is used for the photosensitive resin, and after forming a desired pattern by photolithography technology, the acrylic resin was thermally decomposed by baking to obtain an inorganic pattern. This has the disadvantage that the pattern shrinks during firing, and it is difficult to precisely control the pattern, and further, since it undergoes a firing process, it cannot be handled on a printed circuit board.

We also developed a method of forming a desired pattern by photolithography using a photosensitive paste filled with inorganic fine particles in a photosensitive resin, and obtaining a high dielectric constant composition on the substrate without going through a firing step. (See Patent Document 4). Although there is no need for a firing step, since it contains a photosensitive resin, there are many polar groups and a high dielectric loss.
Although the above method is a chemical etching method, a method of forming a pattern by laser processing is known as a physical etching method. Examples of laser processing methods include excimer laser and YAG high-frequency laser, but these laser processing is suitable for processing micropores, but is not suitable for pattern processing of relatively large shapes of millimeter sizes. There was a problem that the processing speed was slow and not suitable for mass production.

  In addition, there is a method in which a paste prepared by dispersing inorganic particles in a resin before curing is applied and formed in a pattern on a substrate using a screen printing method. However, with this method, it is difficult to accurately form the film thickness and pattern shape.

On the other hand, in order to reduce the size and thickness of the system mounted inside, development of high-density SiP (system in package) that incorporates not only memory but also LSI with a large number of terminals is being carried out at a rapid pace. However, a capacitor built in this SiP is strongly required to be thin, and the film thickness of this capacitor interlayer insulating material is required to be 10 μm or less. Furthermore, since the capacitance of the capacitor is inversely proportional to the thickness of the interlayer insulating material, it is preferable to reduce the thickness of the interlayer insulating material from the viewpoint of increasing the capacitance of the capacitor.
JP-A-5-57852 (Claims) JP-A-6-85413 (Claims) JP-A-5-170517 (Claims) JP 2000-30534 A (Claims) JP-A-8-330181 (paragraphs 17, 19, and 23)

  In view of such circumstances, the present invention aims to pattern the dielectric composition in an arbitrary shape on an arbitrary location on the substrate without impairing the original dielectric constant of the dielectric composition, Provided are a dielectric composition and an optical wiring material that are sufficiently thinned as an interlayer insulating material for a large capacitance capacitor incorporated in a high-density SiP.

  That is, the present invention is a dielectric composition containing an inorganic filler that is at least partially dissolved in a developer and a resin, and the amount of the inorganic filler is 60% by volume of the total amount of solids contained in the dielectric composition. A patterned dielectric composition characterized in that when the film-like dielectric composition is developed and patterned, the taper angle of the film cross section is 70 ° or more and 110 ° or less. is there.

  Another aspect of the present invention is a mixed solution containing an acid and hydrogen peroxide in which a mask pattern is formed on a film-shaped dielectric composition containing an inorganic filler that is at least partially dissolved in a developer and a resin. A method for producing a patterned dielectric composition, wherein the filler component in the dielectric composition is dissolved and patterned by using.

  According to the present invention, it is possible to produce a thin film in which a dielectric composition having a high relative filling of an inorganic filler and having a high relative dielectric constant of 50 or more is patterned with high precision at an arbitrary location. Moreover, since the inorganic filler component of the dielectric composition is dissolved, the resin does not require characteristics such as photosensitivity, so that the resin structure is not limited and any resin can be used. Furthermore, formation of such a dielectric composition can realize light and thin mounting boards.

  The dielectric composition in the present invention is a dielectric composition having a resin and an inorganic filler that is at least partially dissolved in a developer used for patterning. Pattern processing can be performed by dissolving at least a portion of the inorganic filler contained in the composition. One or more inorganic fillers may be used, but one or more inorganic fillers to be used must be soluble in the developer used for patterning. If an inorganic filler that is completely insoluble in the developer is used, the pattern cannot be formed because the inorganic filler does not dissolve in the solution. In addition, the inorganic filler does not need to be completely dissolved, and a part of it may be dissolved. Preferably, the surface layer may be dissolved. The developing solution referred to in the present invention refers to a solution that swells and dissolves the dielectric composition, and also includes what is called an etching solution.

  The amount of the inorganic filler used in the present invention is 60% by volume or more of the total solid content contained in the dielectric composition. Preferably, it is 65 volume% or more, More preferably, it is 70 volume% or more. If the amount of filler is less than 60% by volume, the resin covers the surface of the dielectric composition, and the inorganic filler cannot be in contact with the solution, so that the inorganic filler cannot be dissolved in the solution.

  The solution for dissolving the inorganic filler, that is, the developer used for patterning is not particularly limited as long as it can dissolve the inorganic filler to be used, but a mixed solution of acid and hydrogen peroxide is preferable. It is done. Examples of the acid include sulfuric acid and hydrochloric acid. Sulfuric acid and hydrochloric acid show a strong oxidizing action, but cannot dissolve inorganic fillers such as barium titanate alone. On the other hand, a solution showing alkali is not preferable because it dissolves the resist. It is known that hydrogen peroxide decomposes by releasing oxygen by using various substances such as alkali metal or rough solid surface as a catalyst, but cannot dissolve inorganic fillers such as barium titanate. Therefore, an inorganic filler such as barium titanate can be dissolved by using a mixed solution of acid and hydrogen peroxide. Moreover, the dissolving ability can be enhanced by heating, and the temperature during development is preferably 20 to 80 ° C, more preferably 40 to 60 ° C.

  Moreover, it is preferable that the acid in a mixed solution is 5 volume% or more, and hydrogen peroxide is 1 volume% or more. If the acid is less than 5% by volume and the hydrogen peroxide is less than 1% by volume, a sufficient oxidizing action cannot be obtained, and no dissolution effect is observed. These mixed solutions may contain additives as necessary.

  A method for obtaining the patterned dielectric composition of the present invention will be described with reference to FIG. For example, first, a paste composition in which an inorganic filler is mixed with a resin and a solvent (referred to a state before the dielectric composition is solidified) is prepared, and the paste composition is applied to an adherend (for example, the substrate 1). Then, a method of obtaining a dielectric composition by performing solvent removal and solidification can be mentioned. The method for applying the paste composition is not particularly limited as long as it is a method capable of forming a thin film such as spinner, screen printing, blade coater, die coater. At this time, solidification by heat, light, etc. is mentioned as a solidification method. However, since the dielectric composition of the present invention is not a sintered body, it is not necessary to completely decompose and remove the resin, and it is preferable to heat at a temperature within the heat-resistant temperature range of the electronic component, for example, 500 ° C. or less. . In this way, an unpatterned dielectric composition 2 is obtained.

  Next, a resist is coated on the dielectric composition 2 with a spinner, dried to form a photosensitive layer, and then a light source that emits ultraviolet rays, such as a low pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, an arc, etc., a xenon lamp Etc., exposure is performed through a desired mask pattern, or irradiation is performed while scanning with an electron beam. Next, when this is immersed in a developing solution, when a negative resist is used, an unexposed portion is selectively dissolved and removed to obtain a resist pattern 3 (FIG. 1c). Even when a positive resist is used, the exposed portion is selectively dissolved and removed, and an image faithful to the mask pattern can be obtained.

  Examples of the resist developer used at this time include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, meta-calculated sodium, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, Triethylamine, methyldiethylamine, dimethylethylamine, triethanolamine, tetramethylammonium hydroxide, pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene, 1,5-diazabicyclo [4. An alkaline aqueous solution in which at least one alkaline compound such as 3.0] -5-nonene is dissolved can be used. The concentration of the alkaline aqueous solution is preferably 1 to 10% by weight. If the concentration of the aqueous alkali solution exceeds 10% by weight, the unexposed area is also dissolved in the developer, which is not preferable. In addition, an organic solvent, a surfactant, or the like can be added to the developer composed of an alkaline aqueous solution.

  Subsequently, after developing with the developing solution which consists of alkaline aqueous solution, it wash | cleans with water and dries. Next, when immersed in the developer, the portion of the dielectric composition not protected by the resist swells and dissolves. The step of swelling and dissolving the dielectric composition is referred to as dielectric composition etching or dielectric composition development (FIG. 1d). Hereinafter, dielectric composition etching is used. In the present invention, the dielectric composition etching method is not particularly limited, and examples thereof include a spray method, an immersion method, an immersion rocking method, and an ultrasonic method. Moreover, it is preferable to heat at the temperature at the time of dielectric composition etching at 20-100 degreeC, More preferably, it is 40-70 degreeC. If a residue remains during the etching of the dielectric composition, an increase in spray pressure or physical etching with a brush or the like may be performed. After the pattern formation, the resist pattern 3 is etched (FIG. 1e).

  In addition to the above method, an adherend (FIG. 2a) on which a first resist pattern 4 corresponding to the dielectric composition portion to be etched can be used, which will be described with reference to FIG. A dielectric composition is formed by applying a paste composition to this adherend, removing the solvent, and solidifying (FIG. 2b). A resist is applied on the dielectric composition, exposed through a mask pattern, and developed to form a second resist pattern 5 (FIG. 2c). An inorganic filler is immersed in a developing solution, and the dielectric composition is etched to form an arbitrary dielectric composition pattern (FIG. 2d). Next, the resist pattern 4 and the resist pattern 5 are peeled off (FIG. 2e). In this method, the taper angle of the film cross section can be designed by adjusting the length of a, which is the overlapping portion of the resist pattern 4 and the resist pattern 5 shown in FIG. Therefore, no residue remains in the etched portion of the dielectric composition. As a result, connection reliability is improved even when via connection is performed. However, there is a drawback that the number of steps for forming the resist pattern 4 increases. In the present invention, the pattern of the dielectric composition may be formed by either method.

  The dielectric composition of the present invention is preferably used as an interlayer insulating material for capacitors. The method for forming the interlayer insulating material for capacitors using the dielectric composition is not particularly limited. For example, as described above, after a high dielectric is formed on a substrate, it can be obtained by appropriately forming an electrode.

  The electrode can also be formed prior to patterning the dielectric composition. On the adherend or the adherend on which the resist pattern 4 is formed, the paste composition is applied again, and the solvent composition is removed and solidified to form the dielectric composition. Further, an electrode layer is formed on the dielectric composition. The electrode layer can be formed by an appropriate method such as sputtering, vacuum deposition, electroless plating, electrolytic plating, or hot pressing of copper foil. It is preferable to mainly use copper as the electrode. The copper electrode may be subjected to surface treatment such as CZ treatment, blackening treatment, and buffing. Further, a resist is applied, exposed through a mask pattern, and developed to form a resist pattern 5. After etching copper, it is immersed in a developing solution, the dielectric composition is etched, and a dielectric composition pattern with any electrode can be formed. By using such a method, it is possible to etch copper and a dielectric composition using the same resist pattern.

  Although the resist patterns 3 to 4 are illustrated by taking a negative resist as an example, either a negative resist or a positive resist can be selected. Various additives such as a diluent for diluting these resists, an antioxidant, a thermal polymerization inhibitor, a leveling agent, a surface modifier, and a defoaming agent can also be added.

  The patterned dielectric composition produced by the above method can control the taper angle of the film cross section, preferably 70 ° to 110 °, more preferably 80 ° to 100 °. It is. When the taper angle is less than 70 °, the area of the upper surface and the lower surface of the film is large, which complicates circuit design. In addition, since there is a large difference in the upper and lower diameters of vias in forming via holes, processing is performed based on the minimum diameter, but since densification is limited to the maximum diameter, even if fine processing is performed It becomes difficult to increase the density. When the angle exceeds 110 °, it becomes difficult to make a conductive material for via connection in close contact with the via wall surface, so that the via connection reliability is lowered.

  When the taper angle of the film cross section is 70 ° or more and 110 ° or less, the line width controllability, process management and handling are easy, and it is possible to form a dielectric composition having a substantially rectangular cross section and high shape accuracy. become. In addition, since this manufacturing method does not perform processing with a laser, it is possible to prevent the occurrence of delamination or the like due to thermal damage or increased smear.

  As used in the present invention, the taper angle of the film cross section is defined by the edge of the film cross section and the adherend on which the dielectric composition film (patterned) such as a substrate is formed as shown in FIG. It is the angle (θ).

  The advantage of the dielectric composition pattern forming method of the present invention is that the dielectric composition must contain a photosensitive organic component in addition to the control of the taper angle of the film cross section and the high connection reliability. In addition, since the resin component is not particularly limited, it is possible to use a resin according to the purpose such as low dielectric loss tangent and heat resistance.

  Further, in a dielectric composition having an inorganic filler and a resin, the relative dielectric constant of the dielectric composition follows a formula for deriving the relative dielectric constant of the composite, so-called logarithmic mixing rule (1) described below (ceramic material) Introduction to Science (Applied), Uchida Otsukuru Shinsha, WDKingery, translated by Komatsu Kazuzo et al., P912). The higher the content of the inorganic filler having a high dielectric constant, the higher the relative dielectric constant of the obtained dielectric composition. Conversely, the higher the content of the inorganic filler having a low dielectric constant, the lower the relative dielectric constant of the resulting dielectric composition.

ε: relative permittivity of the composite εi: relative permittivity of each component of the composite Vi: volume fraction of each component of the composite

  In addition to pattern processing, in order to obtain a low linear expansion coefficient and a high relative dielectric constant, it is desirable to contain these inorganic fillers in the resin at a high filling rate. For example, two or more types having different average particle diameters may be mixed and used. When a filler having a single particle size is filled, particularly when the filler is spherical or substantially spherical, a diamond-shaped void is formed between the filler and the filler when filled at a high density. The filler cannot enter. However, if the filler has a size smaller than the gap, the filler can further enter the gap, and the filling rate can be easily improved.

  In addition to these large fillers and small fillers, fillers of other particle sizes may be mixed, and the effect of improving the filling rate by mixing the fillers by appropriately selecting the particle size and blending ratio even if there are three or more types Is obtained.

  Examples of the shape of the inorganic filler include a spherical shape, a substantially spherical shape, an elliptical spherical shape, a needle shape, a plate shape, a scale shape, and a rod shape, and a spherical shape or a substantially spherical shape is particularly preferable. This is because spherical or substantially spherical fillers have the smallest specific surface area, and therefore are less likely to cause filler aggregation and resin fluidity reduction during filling. One of these can be used alone, or two or more can be mixed and used.

  As the inorganic filler used in the present invention, two kinds of inorganic fillers having different average particle diameters can be used, and the average particle diameter of the inorganic filler having the largest average particle diameter is preferably 5 μm or less. More preferably, it is 2 micrometers or less, More preferably, it is 1 micrometer or less. When an inorganic filler having an average particle diameter of greater than 5 μm is used to produce a capacitor having a film thickness of 10 μm or less, the filler tends to protrude from the film surface, so that it is difficult to obtain stable dielectric characteristics. Moreover, when the average particle diameter of the inorganic filler having the maximum average particle diameter is 2 μm or less, the filler in the filler dispersion liquid hardly settles. Furthermore, when the inorganic filler having the maximum average particle diameter has an average particle diameter of 1 μm or less, the filler is difficult to settle during long-term storage.

  Moreover, in this invention, it is preferable that the average particle diameter of the inorganic filler which has the minimum average particle diameter is 0.01-0.1 micrometer. Furthermore, it is more preferable to use a 0.04-0.06 micrometer thing. Since it is necessary to take a difference ratio between the maximum average particle size and the minimum average particle size, the inorganic filler having the minimum average particle size is appropriately selected from the above range depending on the maximum average particle size. The average particle size of the inorganic filler having the smallest average particle size can be increased by increasing the difference ratio from the average particle size of the inorganic filler having the largest average particle size. For this reason, the average particle diameter of the inorganic filler having the smallest average particle diameter is preferably 0.1 μm or less, more preferably, considering the preferred range of the average particle diameter of the inorganic filler having the largest average particle diameter. 0.06 μm or less. An inorganic filler having a small average particle diameter of 0.1 μm or less has a large specific surface area of the filler, and the inorganic filler tends to come into contact with the solution. Therefore, by including an inorganic filler having a small average particle size, pattern formation by dissolution becomes easy.

  The material of the inorganic filler used in the present invention is not particularly limited, and an inorganic filler such as ceramics can be used.

  Examples include barium titanate, barium zirconate titanate, strontium titanate, calcium titanate, bismuth titanate, magnesium titanate, barium neodymium titanate, barium tin titanate, magnesium niobium Barium oxide, barium magnesium tantalate, lead titanate, lead zirconate, lead zirconate titanate, lead niobate, lead magnesium niobate, lead nickel niobate, lead tungstate, tungsten Examples thereof include calcium oxide, lead magnesium tungstate, and titanium dioxide. The barium titanate system includes solid solutions based on barium titanate, in which some elements in the barium titanate crystal are replaced with other elements or other elements are infiltrated into the crystal structure. It is a generic name. Other barium zirconate titanate, strontium titanate, calcium titanate, bismuth titanate, magnesium titanate, barium neodymium titanate, barium tin titanate, barium magnesium niobate, magnesium tantalate Barium, lead titanate, lead zirconate, lead zirconate titanate, lead niobate, lead magnesium niobate, lead nickel niobate, lead tungstate, calcium tungstate, magnesium tungstic acid Both lead-based and titanium dioxide-based are the same, and are generic names including solid solutions that use each as a base material.

  In particular, it is preferable to use a filler having a perovskite crystal structure or a composite perovskite crystal structure. Of these, one kind can be used alone, or two or more kinds can be used in combination, but at least two kinds of inorganic fillers having different average particle diameters have the same chemical composition in terms of dielectric properties. Therefore, it is preferable. In particular, when obtaining a dielectric composition having a high dielectric constant, it is preferable to use a compound mainly composed of barium titanate from the viewpoint of compatibility with commercial convenience. However, for the purpose of improving dielectric properties and temperature stability, a small amount of a shifter, a depressor, etc. may be added.

  Examples of the method for producing the inorganic filler include solid phase reaction methods, hydrothermal synthesis methods, supercritical hydrothermal synthesis methods, sol-gel methods, and oxalate methods. As a method for producing the inorganic filler having the maximum average particle size, it is preferable to use a solid phase reaction method or an oxalate method from the viewpoint of high relative dielectric constant and quality stability. In addition, it is preferable to use one of the hydrothermal synthesis method, the supercritical hydrothermal synthesis method, and the sol-gel method as the method for producing the inorganic filler having the minimum average particle size because it is easy to reduce the particle size. .

  The patterned dielectric composition in the present invention may be used as an interlayer insulating material. In this case, the resin used is, for example, a wire of 30 to 50 ppm / ° C. for polyimide and 50 ppm / ° C. or more for epoxy resin. A resin that satisfies the expansion coefficient is preferred. This is very large compared to the linear expansion coefficient of 17 ppm / ° C. of a wiring metal, for example, copper, but by mixing an inorganic filler, the linear expansion coefficient of the entire dielectric composition is lowered and the linear expansion of the wiring metal is reduced. The difference from the coefficient can be reduced.

  The resin used in the present invention is for dispersing and holding the inorganic filler, and is not particularly limited, and any of thermoplastic and thermosetting resins can be selected. Moreover, since this invention melt | dissolves an inorganic filler, resin does not need to contain photosensitive resin, and the photosensitive organic component contained in resin is 5 volume% or less of the total amount of solid content contained in a dielectric composition. Preferably there is. More preferably, it is 1 volume% or less, More preferably, it is 0 volume%. Examples of the photosensitive resin include a photopolymerizable polymer and a photocrosslinkable polymer. When the photosensitive organic component is 5% by volume or more of the total solid content contained in the dielectric composition, the polar group contained in the photosensitive organic component increases the dielectric loss tangent, thereby forming a dielectric composition having a low dielectric loss tangent. Can not do it.

  As the thermoplastic resin, for example, polyphenylene ether, polyphenylene sulfide, polyether sulfone, polyether imide, liquid crystal polymer, polystyrene, polyethylene, fluorine resin, or the like can be used.

  Thermosetting resins include, for example, epoxy resins, phenol resins, siloxane resins, polyimides, acrylic resins, cyanate resins, benzocyclobutene resins, and other resins that are generally used for insulating layers of printed wiring boards. Can be used. From the viewpoint of solder heat resistance, it is preferable to use a thermosetting resin, and in particular, an epoxy resin is preferably used from the viewpoint of thermosetting shrinkage and viscosity.

  Here, the epoxy resin is a resin having a prepolymer containing two or more epoxy groups (oxirane rings) in the molecular structure. The prepolymer preferably has a biphenyl skeleton or a dicyclopentadiene skeleton from the viewpoint of dielectric properties. Moreover, you may have a hardening | curing agent and hardening agents, such as a phenol novolak resin, a bisphenol A type novolak resin, an aminotriazine compound, a naphthol compound, can be used for a hardening | curing agent. Further, it is possible to add a curing accelerator such as a metal chelate compound such as triphenylphosphine, a benzimidazole compound, or tris (2,4-pentanedionato) cobalt.

  The paste composition in the present invention is composed of an inorganic filler, a resin and a solvent (state before solidification of the dielectric composition), and is obtained by dispersing the inorganic filler in the resin. For example, the inorganic filler is added to the resin solution and mixed and dispersed, or a dispersion in which the inorganic filler is previously dispersed in an appropriate solvent is prepared, and then the dispersion is mixed with the resin solution. The Further, the method for dispersing the inorganic filler in the resin or solvent is not particularly limited. For example, methods such as ultrasonic dispersion, ball mill, roll mill, clear mix, homogenizer, and media disperser can be used. From the viewpoint of properties, it is preferable to use a ball mill or a homogenizer.

  When dispersing the inorganic filler, in order to improve dispersibility, for example, surface treatment of the inorganic filler, addition of a dispersant, addition of a surfactant, addition of a solvent, and the like may be performed. Examples of the surface treatment of the inorganic filler include rosin treatment, acid treatment, basic treatment and the like, in addition to treatment with various coupling agents such as silane, titanium, and aluminum, fatty acids, and phosphate esters. Examples of the addition of the dispersant include dispersants having an acid group such as phosphoric acid, carboxylic acid, fatty acid, and esters thereof. In particular, compounds having a phosphate ester skeleton are preferably used. . In addition, addition of nonionic, cationic, anionic surfactants, wetting agents such as polyvalent carboxylic acids, amphoteric substances, and resins having highly sterically hindered substituents can be mentioned. Moreover, the polarity of the system at the time of dispersion or after dispersion can be controlled by addition of a solvent. Moreover, the paste composition may contain a stabilizer, a dispersant, an anti-settling agent, a plasticizer, an antioxidant, and the like, if necessary. In addition, solid content means what combined the inorganic filler, resin, and other additives.

  The adherend to which the paste composition is applied can be selected from, for example, an organic substrate, an inorganic substrate, and those in which circuit constituent materials are arranged on these substrates. Examples of organic substrates include glass-based copper-clad laminates such as glass cloth / epoxy copper-clad laminates, composite copper-clad laminates such as glass nonwoven fabrics / epoxy copper-clad laminates, polyetherimide resin substrates, polyethers Examples include heat-resistant / thermoplastic substrates such as ketone resin substrates and polysulfone resin substrates, polyester copper-clad film substrates, and polyimide copper-clad film substrates.

  Examples of inorganic substrates include ceramic substrates such as alumina substrates, aluminum nitride substrates, and silicon carbide substrates, and metal substrates such as aluminum base substrates and iron base substrates. Examples of circuit components include conductors containing metals such as silver, gold and copper, resistors containing inorganic oxides, low dielectrics containing glassy materials and / or resins, resins and inorganics Examples thereof include a high dielectric material containing a filler and the like, and an insulator containing a glass-based material.

  The form of the dielectric composition of the present invention is not particularly limited, and can be selected according to applications such as a film shape, a rod shape, a spherical shape, etc., but a film shape is particularly preferable. The membrane here includes a film, a sheet, a plate, a pellet and the like. Of course, it is also possible to perform pattern formation according to applications such as via hole formation for conduction, adjustment of impedance, capacitance or internal stress, or provision of a heat dissipation function.

  The film thickness when the dielectric composition is formed into a film shape can be arbitrarily set within a range in which the capacitance satisfies a desired value, but is preferably 0.5 μm or more and 30 μm or less. More preferably, it is not less than 2 μm and not more than 30 μm. In order to secure a large capacitance as a capacitor, it is preferable that the film thickness is thin. However, if the thickness is less than 0.5 μm, pinholes are easily generated, and electrical insulation is difficult to obtain. When the thickness is 2 μm or more, the dielectric loss tangent hardly increases after PCT (pressure cooker test) which is a durability promotion test. On the other hand, if the film thickness exceeds 30 μm, a large relative dielectric constant is required to obtain sufficient capacitor performance, and it may be difficult to improve the mounting density.

  The use of the patterned dielectric composition of the present invention is not particularly limited. For example, it is used as an interlayer insulating material for a built-in capacitor of a printed wiring board as a high dielectric constant layer, an interlayer insulating film of a multilayer board, a frequency filter It can be applied to various electronic parts and devices such as radio antennas, electromagnetic shields, and optical wiring materials. When used as a capacitor interlayer insulating material, the method for forming the capacitor interlayer insulating material from the dielectric composition is not particularly limited. For example, as described above, after a high dielectric is formed on a substrate, it can be obtained by appropriately forming an electrode.

The capacitance per area of the capacitor interlayer insulating material produced using the dielectric composition of the present invention is preferably in the range of 5 nF / cm ² or more. More preferably, it is in the range of 10 nF / cm ² or more. When the capacitance is less than 5 nF / cm ² , when used as a decoupling capacitor, the entire system cannot be sufficiently separated from the power supply system and cannot function sufficiently as a decoupling capacitor.

  The smaller the capacitance change in temperature and the in-plane variation, the better in terms of circuit design. The temperature change is preferably as small as possible. For example, it is preferable to satisfy the X7R characteristic (capacitance temperature change rate within −15% at −55 to 125 ° C.). The in-plane variation in capacitance is preferably 5% or less (average capacitance value−5% ≦ capacitance ≦ average capacitance value + 5%) with respect to the average value.

In order to reduce the power loss of the power source, the dielectric loss tangent of the capacitor is preferably in the range of 0.01 to 5%, and more preferably in the range of 0.01 to 1%. Here, electrical characteristics such as capacitance and dielectric loss tangent are measured values at a frequency of 20 k to 1 GHz.
The electrostatic capacity, relative dielectric constant, and dielectric loss tangent of the dielectric composition can be measured as follows, for example, according to JIS K6911. That is, a coating film of a high dielectric composition is formed on the entire surface of an aluminum substrate having an area of 10 cm × 10 cm and a thickness of 0.3 mm. An electrode for measurement is formed by pattern-printing a conductive paste on the coating film. A portion sandwiched between the measurement electrode and the aluminum substrate is a measurement target region. The capacitance and dielectric loss tangent of the measurement target region are measured by an impedance analyzer (for example, 4294A manufactured by Agilent Technologies). The relative dielectric constant is calculated from the capacitance and the dimension of the measurement target region. From the viewpoint of reducing measurement noise, the pattern of the measurement electrode on the coating film is circular, and a ring-shaped electrode (referred to as a guard electrode) so as to surround the circular pattern at a distance of 0.5 to 1 mm from the outer periphery of the measurement electrode. Is preferable. Since the dimensions of the measurement target area, that is, the diameter (area) of the measurement electrode and the film thickness of the dielectric composition affect the measurement accuracy, it is necessary to select conditions that match the physical properties of the dielectric composition. In the present invention, the measurement electrode is a circular pattern having a diameter of 10 mm, the guard electrode is a ring pattern having an inner diameter of 11.5 mm, and the film thickness of the dielectric composition is in the range of 10 μm to 20 μm. The dielectric composition coating was formed by appropriately heating the spin-coated paste composition, evaporating the solvent, and curing the resin. In addition, since the temperature and moisture absorption state also affect the dielectric properties, the dielectric properties can be evaluated with good reproducibility by performing measurements after leaving the high dielectric composition in a measurement temperature constant temperature and humidity atmosphere for 24 hours. it can.

  The dielectric composition in the present invention can be preferably used as an optical wiring material. Optical wiring refers to wiring in a system in which signal transmission between LSIs, modules, boards, and the like is performed not by normal electrical signals but by optical signals. When an optical wiring is formed on or in the mounting substrate, a structure in which a layer having a high refractive index is sandwiched between layers having a low refractive index is employed. It is also possible to substitute a layer having a low refractive index with a space. When used as an optical wiring material, it is important to use an inorganic filler that is sufficiently smaller than the wavelength of the light in order to reduce the scattering of light for signal transmission guided in the optical wiring. The particle size is preferably ¼ or less. Further, the refractive index, the temperature dependency of the refractive index, and the thermal expansion coefficient can be controlled from the selection of the inorganic filler material, the content, and the resin material. This broadens the range of choice of substrate material for forming the optical wiring layer, making it possible to use not only conventional materials made of inorganic materials such as silicon and ceramics, but also substrates made of organic materials. Become.

  By forming such a dielectric composition, the mounting substrate can be reduced in thickness, thickness, and a highly reliable capacitor can be obtained with a small occupied area. Furthermore, since it is suitable for a large capacitance, it is useful as a capacitor incorporated in a high-density SiP or an interlayer insulating material for circuit board materials having a function as a capacitor.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1
2. 323 parts by weight of barium titanate filler (manufactured by Sakai Chemical Co., Ltd., BT-05, average particle size: 0.5 μm), 36 parts by weight of γ-butyrolactone, dispersant (BYK-W9010, manufactured by BYK Chemie) 2 parts by weight were mixed and dispersed for 1 hour under ice-cooling using a homogenizer to obtain dispersion A-1. 12.8 parts by weight of epoxy resin (manufactured by Nippon Kayaku Co., Ltd., EPPN502H), 7.8 parts by weight of phenol novolac resin (manufactured by Dainippon Ink Industries, Ltd., TD-2131), curing accelerator (Hokuko Chemical Co., Ltd.) ), Triphenylphosphine) 0.2 parts by weight and 21 parts by weight of γ-butyrolactone were mixed to obtain an epoxy resin solution B-1. Dispersion A-1 and epoxy resin solution B-1 were mixed using a ball mill to prepare paste composition C-1.
This paste composition was applied onto a copper-clad FR-4 substrate using a die coater, dried in an oven at 80 ° C. for 15 minutes, cured at 175 ° C. for 4 hours, and a film thickness of 10 μm. Dielectric composition D-1a was obtained. The content of the inorganic filler in this dielectric composition was 75% by volume in the solid content.

  Next, negative resist PMER N-HC600 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) was applied to the dielectric composition D-1a using a spinner, dried, and subjected to pattern exposure by a mask method. Subsequently, after developing using PMER developing solution N-A5 Tokyo Ohka Co., Ltd. which develops the resist, it was washed with water to form a resist pattern. A line and space pattern with different line intervals was used as the mask pattern. Next, a mixed solution of 8.5% by volume sulfuric acid (stock solution concentration 98%) and 4.5% by volume hydrogen peroxide solution (stock solution concentration 35%) was heated to 55 ° C. for 25 minutes by the immersion rocking method. Etching of the dielectric composition was performed. Further, the residual dielectric composition was peeled off by spraying using the same mixed solution. After forming the dielectric composition pattern, the resist was peeled off by immersing in 4% sodium hydroxide for 3 to 5 minutes. The line and space (L / S) of the dielectric composition is observed using an optical microscope, the cross-sectional shape of the dielectric composition is measured using an electron microscope, and the taper angle (θ) of the film cross section is measured. Observations were made. The results are shown in Table 1.

  In addition, this paste composition C-1 was applied on a 300 μm thick aluminum substrate using a die coater, dried in an oven at 80 ° C. for 15 minutes, and then cured at 175 ° C. for 4 hours. A dielectric composition having a thickness of 10 μm was obtained. An aluminum electrode having a diameter of 11 mm was formed on this dielectric composition by vapor deposition, and the dielectric characteristics at 1 MHz were measured according to JIS K 6911 using impedance analyzer HP4284A and sample holder HP16451B (both manufactured by Hewlett Packard). Is shown in Table 1.

Example 2
It carried out according to the process shown by FIG. First, negative resist N-HC600 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) was applied on a copper-clad FR-4 substrate using a spinner, dried, and subjected to pattern exposure by a mask method. The paste composition C-1 was applied to a copper-clad substrate with a resist pattern, dried in an oven at 80 ° C. for 15 minutes, and then cured at 175 ° C. for 4 hours to obtain a dielectric composition having a thickness of 10 μm. D-1b was obtained. The content of the inorganic filler in this dielectric composition was 75% by volume in the solid content. A negative resist N-HC600 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) was applied to the dielectric composition D-1b using a spinner, dried, subjected to pattern exposure by a mask method, developed, and washed with water. At this time, a mask in which the exposed portion and the unexposed portion of the mask used on the copper-clad substrate were reversed was used. Moreover, alignment of the mask was performed using an aligner. Next, a mixed solution of 8.5% by volume sulfuric acid (stock solution concentration: 98%) and 4.5% by volume hydrogen peroxide solution (stock solution concentration: 35%) is heated to 55 ° C. and immersed for 25 minutes by the immersion method. Things were etched. Further, the residual dielectric composition was peeled off by spraying using the same mixed solution. After forming the dielectric composition pattern, the resist was peeled off by immersing in 4% sodium hydroxide for 3 to 5 minutes. Table 1 shows the results of the line and space (L / S) of the dielectric composition pattern and the taper angle (θ) of the film cross section based on the method of Example 1.

Example 3
62.3 parts by weight of barium titanate (manufactured by Sakai Chemical Co., Ltd., BT-05: average particle size 0.5 μm), barium titanate (manufactured by Cabot, K-Plus 16: average particle size 0.06 μm) 21.9 Parts by weight, 15 parts by weight of γ-butyrolactone, 0.8 parts by weight of a dispersant (a copolymer having an acid group having a phosphate ester skeleton, BYK-Japan 90, BYK-W9010) was kneaded using a homogenizer, Dispersion A-2 was obtained. 2.6 parts by weight of epoxy resin (manufactured by Nippon Kayaku Co., Ltd., NC-3000), 0.9 part by weight of phenol novolac resin (manufactured by Nippon Kayaku Co., Ltd., “Kayahard” KTG-105), curing accelerator ( Hokuko Chemical Co., Ltd., triphenylphosphine) 0.04 parts by weight and γ-butyrolactone 7.1 parts by weight were mixed to obtain an epoxy resin solution B-2. Dispersion A-2 and epoxy resin solution B-2 were mixed using a ball mill to prepare paste composition C-2. Except for using the paste composition C-2, the line and space (L / S) of the dielectric composition pattern, the taper angle (θ) and the dielectric characteristics of the dielectric composition pattern were determined based on the method of Example 1. The evaluation results are shown in Table 1. Further, the content of the inorganic filler in the dielectric composition in Example 3 was 82% by volume in the solid content.

Example 4
A dielectric composition pattern was prepared and evaluated in the same manner as in Example 2 except that the paste composition C-2 was used. The results are shown in Table 1.

Example 5
A pattern of the dielectric composition was prepared in the same manner as in Example 3 except that the thickness of the dielectric composition was 50 μm, and the results are shown in Table 1. The content of the inorganic filler in the dielectric composition in Comparative Example 3 was 82% by volume in the solid content.

Comparative Example 1
A dielectric composition pattern was prepared in the same manner as in Example 3 except that the developer used for etching the dielectric composition was 8.5% by volume sulfuric acid (stock solution concentration: 98%). The results are shown in Table 1. It was.

Comparative Example 2
Epoxy resin (Nippon Kayaku Co., Ltd., NC-3000) 15.1 parts by weight, phenol novolac resin (Nippon Kayaku Co., Ltd., “Kayahard” KTG-105) 5.9 parts by weight, curing accelerator ( Hokuko Chemical Co., Ltd., triphenylphosphine) 0.2 parts by weight and γ-butyrolactone 8.5 parts by weight were mixed to obtain an epoxy resin solution B-3. Dispersion A-2 obtained in Example 3 and epoxy resin solution B-3 were mixed using a ball mill to prepare paste composition C-3.
A dielectric composition was prepared and evaluated in the same manner as in Example 1 except that this paste composition C-3 was used. The results are shown in Table 1. The content of the inorganic filler in the dielectric composition in Comparative Example 2 was 43% by volume in the solid content.

Comparative Example 3
The paste composition C-1 was printed on a copper-clad substrate using a screen mask (SUS # 325 mesh) having a line-and-space pattern with different line intervals, dried at 80 ° C. for 15 minutes, and then 175 ° C. × Curing was performed in 4 hours to obtain a patterned dielectric composition having a thickness of 10 μm. Based on the method of Example 1, the results of the line and space (L / S) of the dielectric composition pattern and the taper angle (θ) of the film cross section are shown in Table 1. Moreover, content of the inorganic filler of the dielectric material composition in the comparative example 4 was 75 volume% in solid content.

Comparative Example 4
The same process as in Example 1 was performed until the step of forming the dielectric composition D-1a. Next, patterning was performed using laser processing to produce a dielectric composition pattern. The laser processing was performed with a carbon dioxide laser under the condition of a pulse width of 20 μsec. Based on the method of Example 1, the results of the line and space (L / S) of the dielectric composition pattern and the taper angle (θ) of the film cross section are shown in Table 1. The content of the inorganic filler in the dielectric composition in Comparative Example 5 was 75% by volume in the solid content.

  Note that “a” in Table 1 is “a” described in FIG. 3 and indicates the length of the overlapping portion of the resist pattern. Also, the resist patterns 3, 4, and 5 in Table 1 are the resist patterns 3, 4, and 5 described in FIGS.

Schematic diagram of dielectric composition pattern preparation step (1) Schematic diagram of dielectric composition pattern preparation step (2) Resist pattern layout Figure of taper angle θ of membrane cross section

Explanation of symbols

1 Substrate (Substrate)
2 Unpatterned dielectric composition 3, 4, 5 Resist pattern 6 Patterned dielectric composition

Claims (6)

A dielectric composition containing an inorganic filler that is at least partially dissolved in a developer and a resin, wherein the amount of the inorganic filler is 60% by volume or more of the total amount of solids contained in the dielectric composition, A patterned dielectric composition characterized in that when the shaped dielectric composition is developed and patterned, the taper angle of the film cross section is 70 ° or more and 110 ° or less. The patterned dielectric composition according to claim 1, wherein the developer is a mixed solution containing an acid and hydrogen peroxide. The patterned dielectric composition of claim 1, wherein the inorganic filler comprises barium titanate. A patterned dielectric composition, wherein the dielectric composition according to claim 1 has a thickness of 2 μm or more and 30 μm or less. Form a mask pattern on a film-shaped dielectric composition containing an inorganic filler that is at least partially dissolved in a developer and a resin, and use a mixed solution containing an acid and hydrogen peroxide to fill the filler in the dielectric composition A method for producing a patterned dielectric composition, comprising dissolving and patterning components. The acid in the mixed solution is 5% by volume or more and the hydrogen peroxide is 1% by volume or more, and the mixed solution is used to dissolve and pattern the filler component in the dielectric composition. Item 6. A method for producing a patterned dielectric composition according to Item 5.

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