JP5836777B2 - Wiring board - Google Patents

Description

  The present invention relates to a wiring board used for electronic devices (for example, various audiovisual devices, home appliances, communication devices, computer devices, and peripheral devices thereof).

  Conventionally, as a wiring board used in an electronic device, for example, a wiring board having an insulating layer made of a resin material as disclosed in Patent Document 1 is used.

  However, since the conventional wiring board uses a resin material for the insulating layer, the difference in thermal expansion between the wiring board and the electronic component mounted on the wiring board becomes large.

  Then, due to the difference in thermal expansion, stress is easily applied to the connection portion between the wiring board and the electronic component, and as a result, the connection reliability of the wiring board has been reduced.

JP-A-8-116174

  An object of the present invention is to provide a wiring board with improved electrical reliability and a mounting structure using the wiring board.

Wiring board according to an embodiment of the present invention includes an insulating layer, and a formed in the insulating layer over the conductive layer, the insulating layer is smaller particle size than the wavelength of visible light, or hanging even without least a plurality of first inorganic insulating particles partially connected to each other, larger particle size than the first inorganic insulating particles, the first inorganic insulating particles with intervening first inorganic insulating particles between each other A plurality of colorant particles bonded to each other , and a plurality of second inorganic insulating particles having a particle diameter larger than the wavelength of visible light and at least partially connected to each other via the first inorganic insulating particles A plurality of the first and second inorganic insulating particles and a resin material filled around the plurality of the colorant particles, and the colorant
The particles have a smaller particle size than the second inorganic insulating particles .

According to the wiring board according to an embodiment of the present invention, the insulating layer is smaller particle size than the wavelength of visible light, and if Tsu even without least a plurality of partially connected to one another first inorganic insulating particles, A plurality of colorant particles having a particle size larger than that of the first inorganic insulating particles and interposing the first inorganic insulating particles between the first inorganic insulating particles and being bonded to the first inorganic insulating particles; A plurality of second inorganic insulating particles having a large particle size and at least a part of which are connected to each other via the first inorganic insulating particles, and the insulating layer has a first inorganic insulating particle having a low coefficient of thermal expansion. Since it is formed as a main component, the thermal expansion coefficient of the insulating layer can be reduced. As a result, application of thermal stress to the connection portion between the wiring board and the electronic component can be reduced, and the electrical reliability of the wiring board can be improved.

The insulating layer has a first inorganic insulating particle having a particle diameter smaller than the wavelength of visible light, and a particle diameter larger than the first inorganic insulating particle, and the first inorganic insulating particles are interposed between each other. By having a plurality of separated colorant particles and second inorganic insulating particles having a particle size larger than that of the colorant particles , the insulating layer is uniformly colored and formed on the colored insulating layer and the insulating layer. The distinguishability from the conductive layer formed can be improved. As a result, it becomes easy to reduce inspection errors of the patterned conductive layer, and thus electrical reliability can be improved.

It is sectional drawing which cut | disconnected the mounting structure concerning one Embodiment of this invention in the thickness direction. FIG. 2 is an enlarged cross-sectional view of the R1 portion of the mounting structure shown in FIG. 3 is an enlarged cross-sectional view of the R2 portion of the mounting structure shown in FIG. 4 (a) and 4 (b) are cross-sectional views cut in the thickness direction for explaining the manufacturing process of the mounting structure shown in FIG. 1, and FIG. 4 (c) is an R3 portion of FIG. 4 (b). It is sectional drawing which expanded and showed. 5A to 5C are cross-sectional views cut in the thickness direction for explaining the manufacturing process of the mounting structure shown in FIG. 6A to 6C are cross-sectional views cut in the thickness direction for explaining the manufacturing process of the mounting structure shown in FIG. 7 (a) and 7 (b) are cross-sectional views cut in the thickness direction for explaining the manufacturing process of the mounting structure shown in FIG.

  Hereinafter, a mounting structure including a wiring board according to an embodiment of the present invention will be described in detail with reference to the drawings.

  A mounting structure 1 according to an embodiment of the present invention shown in FIG. 1 is used for electronic devices such as various audiovisual devices, home appliances, communication devices, computer devices or peripheral devices thereof. The mounting structure 1 includes an electronic component 2 and a wiring board 3 on which the electronic component 2 is mounted.

  The electronic component 2 is a semiconductor element such as an IC or LSI, and is flip-chip mounted on the wiring substrate 3 via bumps 4 made of a conductive material such as solder.

  The wiring board 3 supports the electronic component 2 and has a function of supplying power and signals for driving or controlling the electronic component 2 to the electronic component 2. The wiring substrate 3 includes a core substrate 5 and a pair of buildup layers 6 formed on both main surfaces of the core substrate 5.

  The core substrate 5 is intended to enhance electrical connection between the pair of buildup layers 6 while increasing the rigidity of the wiring substrate 3. The core substrate 5 includes a base body 7, an insulating layer 8 formed on both main surfaces of the base body 7, a cylindrical through-hole conductor 9 formed through the base body 7 and the insulating layer 8, and a through-hole conductor. 9 and an insulator 10 that fills the hollow of 9.

  The base 7 increases the rigidity of the core substrate 5. The base 7 includes, for example, a resin part 11 and a base material 12 covered with the resin part 11. The coefficient of thermal expansion in the planar direction of the substrate 7 is set to, for example, 3 ppm / ° C. or more and 20 ppm / ° C. or less. The coefficient of thermal expansion in the thickness direction of the substrate 7 is set to, for example, 30 ppm / ° C. or more and 50 ppm / ° C. or less. Here, the coefficient of thermal expansion is measured by a measuring method according to JISK7197-1991 using, for example, a commercially available TMA (Thermo-Mechanical Analysis) apparatus.

  The resin part 11 is a main part of the base body 7. The resin portion 11 is made of, for example, epoxy resin, bismaleimide triazine resin, cyanate resin, polyparaphenylene benzbisoxazole resin, wholly aromatic polyamide resin, polyimide resin, aromatic liquid crystal polyester resin, polyether ether ketone resin or polyether ketone. A material such as a resin can be used. The thermal expansion coefficient of the resin part 11 is set to, for example, 20 ppm / ° C. or less and 50 ppm / ° C. or less.

  The base 12 reduces thermal expansion while increasing the rigidity of the base 7. This base material 12 can use what arranged the woven fabric or the nonwoven fabric fiber comprised by the fiber in one direction. As the fiber, for example, glass fiber, resin fiber, carbon fiber or metal fiber can be used.

  The insulating layer 8 supports the conductive layer 13 included in the buildup layers 6 formed on both main surfaces of the core substrate 5 while reducing the thermal expansion while increasing the rigidity of the core substrate 5. The insulating layer 8 includes an inorganic insulating structure 14 and a resin material 15 filled in a gap of the inorganic insulating structure 14.

  The insulating layer 8 preferably contains 65% by volume or more of the inorganic insulating structure 14 and 35% by volume or less of the resin material 12. As a result, the thermal expansion coefficient in the planar direction and the thickness direction of the insulating layer 8 is set to, for example, 0 ppm / ° C. or more and 10 ppm / ° C. or less. The volume content is determined by photographing the polished surface of the inorganic insulating layer 8 with a field emission electron microscope, and using an image analysis device or the like, the area ratio (area%) of the inorganic insulating structure 14 is set to 10 cross sections. It is calculated | required by calculating the average value of the measured value, and considering it as content (volume%).

  The inorganic insulating structure 14 is a main part of the insulating layer 8 and improves the rigidity of the insulating layer 8 and reduces thermal expansion. The inorganic insulating structure 14 includes a first inorganic insulating particle 16, a colorant particle 17 having a larger particle diameter than the first inorganic insulating particle 16, and a second inorganic insulating particle 18 having a larger particle diameter than the colorant particle 17. Including. As shown in FIG. 2 and FIG. 3, the inorganic insulating structure 14 includes a plurality of first inorganic insulating particles 16 arranged between a plurality of second inorganic insulating particles 18 and a plurality of coloring material particles 17, or 2 Intervene between the inorganic insulating particles 18 and the colorant particles 17. In addition, the first inorganic insulating particles 16 in the inorganic insulating structure 14 and the first inorganic insulating particles 16 and the second inorganic insulating particles 18 are connected to each other through a neck structure at least in part. The inorganic insulating structure 14 has a gap surrounded by the plurality of first and second inorganic insulating particles 16 and 18 and the neck structure.

  The inorganic insulating structure 14 includes 6% to 35% by volume of the first inorganic insulating particles 16, includes 60% to 93% by volume of the second inorganic insulating particles 18, and includes 1% by volume or more of the colorant particles 17. It is desirable to contain 5 volume% or less.

  As a result, since the first inorganic insulating particles 16 and the second inorganic insulating particles 18 having a small coefficient of thermal expansion are the main components, the coefficient of thermal expansion of the inorganic insulating structure 14 is reduced. In addition, since the plurality of coloring material particles 17 are arranged apart from each other, the aggregation of the coloring material particles 17 in the inorganic insulating structure 14 can be effectively suppressed, so that the inorganic insulating structure 14 Can be uniformly colored to improve the discrimination between the insulating layer 8 and the conductive layer 13 formed on the insulating layer 8.

  The first inorganic insulating particles 16 constitute the main part of the inorganic insulating structure 14. The first inorganic insulating particles 16 are made of, for example, silicon oxide, aluminum oxide, magnesium oxide, or calcium oxide in order to satisfactorily insulate the inorganic insulating structure 14. The first inorganic insulating particles 16 are preferably made of an amorphous material. As a result, the generation of cracks in the inorganic insulating structure 14 due to the crystal structure of the first inorganic insulating particles 16 can be reduced. The first inorganic insulating particles 16 are preferably spherical. Since it becomes easy to fill the 1st inorganic insulating particle 16 when it is spherical, the internal structure of the inorganic insulating structure 14 can be made dense.

The particle diameter of the first inorganic insulating particles 16 is smaller than the wavelength of visible light. As a result, since the particle diameter of the first inorganic insulating particles 16 is very small, the specific surface area is large, the surface energy is increased, and the surface atoms actively move. The first inorganic insulating particles 16 or the second inorganic insulating particles 18 are firmly bonded. In addition, the wavelength of visible light means a thing whose wavelength range is 360 nm or more and 830 nm or less according to JISZ8120-2001. Therefore, the particle diameter of the first inorganic insulating particles 16 is preferably smaller than 360 nm which is the lower limit value of the visible light wavelength range.

  In particular, the first inorganic insulating particles 16 preferably have a particle size of 3 nm to 110 nm. When the particle size is in this range, the first inorganic insulating particles 16 are maintained at a low temperature, such as the crystal start temperature or lower, while maintaining the crystal structure of the first inorganic insulating particles 16 that are amorphous. They can be firmly bonded to each other.

  The particle diameter of the first inorganic insulating particles 16 is obtained by observing the polished surface or fractured surface of the insulating layer 8 with a field emission electron microscope and expanding the cross section so as to include particles of 20 particles or more and 50 particles or less. This is obtained by photographing and measuring the maximum diameter appearing in this enlarged cross section of each particle to calculate an average value. Hereinafter, the particle diameters of the colorant particles 17 and the second inorganic insulating particles 18 are also determined by measurement in the same manner as the particle diameters of the first inorganic insulating particles 16.

  The colorant particles 17 are for coloring the inorganic insulating structure 14 and thus the insulating layer 8 by selectively absorbing the wavelength of visible light. The colorant particles 17 are made of an inorganic material such as bengara, ultramarine, zinc yellow, zinc green, peacock stone, manganese violet, methyl violet, graphite, iron oxide black, and the like. Further, the colorant particles 17 have a particle size set to 0.4 μm or more and 0.9 μm or less, for example.

  The second inorganic insulating particles 18 form the main part of the inorganic insulating structure 14 together with the first inorganic insulating particles 16. The second inorganic insulating particles 18 are made of, for example, silicon oxide, aluminum oxide, magnesium oxide, or calcium oxide. The first inorganic insulating particles 16 are preferably made of an amorphous material in order to reduce the generation of cracks in the inorganic insulating structure 14 due to the crystal structure of the first inorganic insulating particles 16. The second inorganic insulating particles 18 are preferably spherical. When it is spherical, the surface of the second inorganic insulating particle 18 becomes smooth, and stress on the surface is dispersed, so that the generation of cracks starting from the surface of the second inorganic insulating particle 18 can be reduced.

  Further, the second inorganic insulating particles 18 have a larger particle size than the first inorganic insulating particles 16. As a result, in the extension of the crack in the inorganic insulating structure 14 generated by breaking the bond between the first inorganic insulating particles 16, the crack extends around the second inorganic insulating particle 18 having a large particle diameter. A large amount of energy is required for the extension. Therefore, the extension of cracks in the inorganic insulating structure 14 can be satisfactorily suppressed by the second inorganic insulating particles 18 having a particle diameter larger than that of the first inorganic insulating particles 16. The particle diameter of the second inorganic insulating particles 18 is set to be larger than the minimum value (360 nm) of the wavelength of visible light, and is set to 0.5 μm or more and 5 μm or less, for example. The particle diameter of the second inorganic insulating particles 18 is desirably set to be larger than the maximum value of visible light wavelength (830 nm).

  The second inorganic insulating particles 18 are preferably formed of the same material as the first inorganic insulating particles 16. In this case, the bonds between the particles are strengthened, and cracks generated in the inorganic insulating structure 14 can be favorably reduced. Note that the second inorganic insulating particles 18 may be formed of a material different from that of the first inorganic insulating particles 16.

The resin material 15 is filled around the first inorganic insulating particles 16, the colorant particles 17 and the second inorganic insulating particles 18 included in the insulating layer 8. For example, an epoxy resin, a polyimide resin, an acrylic resin, and a cyanate resin are used. Resin materials such as fluororesin, silicon resin, polyphenylene ether resin, and bismaleide triazine resin can be used. In addition, the refractive index of the resin material 15 is different from that of the second inorganic insulating particles 18. Such resin material 15
For example, the refractive index is set to be smaller than 0.9 times the refractive index of the second inorganic insulating particles 18 or larger than 1.1 times the refractive index of the second inorganic insulating particles 18.

  The resin material 15 filled in the gaps of the inorganic insulating structure 14 is preferably an epoxy resin among the above resin materials. Since the epoxy resin has a molecular structure suitable for adhesion, the adhesion between the colorant particles 17 and the resin material 15 becomes stronger, the insulating layer 8 is less likely to crack, and the substrate can be made thinner. Can do.

  Further, if the surface of the colorant particle 17 is appropriately treated with a silane coupling agent, the hydroxyl group disposed on the surface of the colorant particle 17 is firmly bonded to the epoxy group of the resin material 15. Epoxy groups react with moisture in the atmosphere to form hydroxyl groups (OH groups) at both ends, and then the hydroxyl groups formed on the epoxy groups and the hydroxyl groups disposed on the surface of the colorant particles 17 undergo dehydration condensation. Thus, the epoxy group of the resin material 15 is preferably bonded to the hydroxyl group disposed on the surface of the colorant particle 17, and the adhesion to the resin material 15 becomes strong, which is preferable in that the strength of the wiring board 3 can be further improved.

  On the other hand, as described above, a pair of buildup layers 6 are formed on the upper and lower surfaces of the core substrate 5. The buildup layer 6 includes an insulating layer 8, a conductive layer 13, and a via conductor 19.

  The insulating layer 8 functions as a supporting member that supports the conductive layer 13 described later, functions as an insulating member that suppresses short circuit between the conductive layers 13, and is the same as described above. And it laminates | stacks through the contact bonding layer 20 which consists of the material similar to the resin material 15 mentioned above.

  The conductive layers 13 are formed on the insulating layer 8 and are arranged apart from each other in the thickness direction via the insulating layer 8. As the conductive layer 13, for example, a layer formed of a metal material such as copper, silver, gold, aluminum, or nickel chrome can be used.

  The via conductor 19 connects the conductive layers 13 arranged apart from each other in the thickness direction, and is formed in a columnar shape whose diameter decreases toward the core substrate 5. As the via conductor 19, for example, a conductor formed of a conductive material such as copper, silver, gold, aluminum, or nickel chrome can be used.

  The conductive layer 13 and the via conductor 19 are electrically connected to each other, and constitute a wiring portion including a ground wiring, a power supply wiring, and / or a signal wiring.

  By the way, since the particle diameter of the first inorganic insulating particles 16 is smaller than the wavelength of visible light, the visible light is not easily reflected by the first inorganic insulating particles 16, and thus easily passes through the inorganic insulating structure 14. When the visible light reaches the second inorganic insulating particles 18 that are spheres larger than the wavelength of visible light, the light is likely to be reflected (recursive reflection) in the same direction as the incident direction. Specifically, this occurs as follows.

  First, when visible light reaches the outer surface of the second inorganic insulating particle 18 that is larger than the wavelength of visible light, the visible light generally has high translucent silicon oxide, aluminum oxide, magnesium oxide, calcium oxide, or the like. It enters the second inorganic insulating particles 18 made of the following material. The visible light that has entered the second inorganic insulating particles 18 is reflected on the inner surface of the second inorganic insulating particles 18 due to the difference in refractive index between the second inorganic insulating particles 18 and the resin material 15, and the second It goes out of the inorganic insulating particles 18. At this time, the reflected visible light is refracted when entering the second inorganic insulating particles 18, reflected on the inner surface of the second inorganic insulating particles 18, and when going out of the second inorganic insulating particles 18. Due to the refraction, light is reflected (recursively reflected) in the same direction as the direction of incidence on the second inorganic insulating particles 18.

  Here, for example, when inspecting the wiring pattern of the conductive layer 13 formed on the insulating layer 8 by irradiating light and using the contrast of the reflected light, if the insulating layer 8 is easily retroreflected, the irradiated light The insulating layer 8 is recognized as a member that reflects in the same manner as the conductive layer 13 having a metallic luster, and the distinguishability between the conductive layer 13 and the insulating layer 8 tends to decrease.

  On the other hand, in the wiring substrate 3 of the present embodiment, since the inorganic insulating structure 14 includes the colorant particles 17, the colorant particles 17 absorb visible light, and thus pass through the inorganic insulating structure 14. The amount of visible light reflected from the inorganic insulating structure 14 can be reduced. Therefore, since the reflection of visible light due to the above-described retroreflection can be reduced in the insulating layer 8, the distinguishability between the conductive layer 13 and the insulating layer 8 can be improved.

  In addition, regarding the inspection of the pattern of the conductive layer 13 and the like, when using an inspection method for irradiating the wiring board 3 with light and analyzing the reflected light, the lightness, saturation, and hue of the irradiated light can be arbitrarily selected. Then, the selected light is irradiated. Then, based on the parameter where the contrast difference is most recognized with respect to the reflected light, the wiring pattern formed by the conductive layer 13 is recognized and the suitability of the wiring pattern is examined. In this case, for example, when the wiring pattern is inspected based on the brightness, if the brightness difference between the insulating layer 8 and the conductive layer 13 is, for example, 10% or more, the two can be reliably identified. Here, the brightness is measured by, for example, a spectrophotometer (Hitachi U-4100).

  The colorant particles 17 function to enhance the contrast between the insulating layer 8 and the conductive layer 13 in any one of brightness, saturation, and hue. For example, Bengala is brown, Ultramarine is blue, and zinc yellow The insulating layer 8 is colored yellow, zinc green and peacock stone are green, manganese violet and methyl violet are purple, graphite is gray, and iron oxide black is black. Of these, gray and black are tone colors resulting from absorption of visible light having many wavelengths. Therefore, in order to efficiently reduce the amount of light reflected by the insulating layer 8, graphite or iron oxide black is used for the colorant particles 17. It is preferable to use it.

  As described above, the colorant particles 17 are preferably contained in the inorganic insulating structure 14 in an amount of 1% by volume to 5% by volume. By including 1% by volume or more of the colorant particles 17, the insulating layer 8 is favorably colored, and when 5% by volume or less is included, the electrical characteristics of the wiring board 3 can be satisfactorily maintained.

  In addition, as described above, the inorganic insulating structure 14 includes the plurality of first inorganic insulating particles 16 interposed between the plurality of colorant particles 17. That is, by interposing the plurality of first inorganic insulating particles 16 between the colorant particles 17, the plurality of colorant particles 17 are separated from each other and are uniformly distributed in the insulating layer 8. Yes. As a result, the insulating layer 8 can absorb incident light or reflected light substantially uniformly and can uniformly color the insulating layer 8, thereby improving the distinguishability from the wiring pattern by the conductive layer 13. be able to.

  Further, if the colorant particles 17 are made of an inorganic material, it is preferable in that the insulating layer 8 can have low thermal expansion. Among them, if the colorant particle 17 is an oxide, the oxygen atom of the colorant particle 17 and the oxygen atom of the first inorganic insulating particle 16 are hydrogen-bonded through water atoms in the atmosphere, and the wiring board 3 It is preferable in that the elastic modulus can be increased and the strength can be increased.

The inorganic insulating structure 14 is formed by bonding the first inorganic insulating particles 16 to the first inorganic insulating particles 16 and the second inorganic insulating particle particles 18 at least partially via a neck structure, The first inorganic insulating particles 16, the second inorganic insulating particles 18 and the colorant particles 17 included in the inorganic insulating structure 14 are preferably present in a spherical shape. Since the colorant particles 17 are also spherical, the light incident from various directions uniformly strikes the colorant particles 17 regardless of the incident angle, or the light reflected by the colorant particles 17 is Since the light can be diffused in various directions depending on the difference in the angle of incident light, and light can be scattered in the insulating layer 8, the occurrence of color spots and the like in the colored insulating layer 8 can be reduced satisfactorily.

  Furthermore, the colorant particles 17 are preferably larger than the first inorganic insulating particles 16 and smaller than the second inorganic insulating particles 18. Since the colorant particles 17 are larger than the first inorganic insulating particles 16, the light transmitted through the plurality of first inorganic insulating particles 16 arranged around the colorant particles 17, or reflected by the first inorganic insulating particles 16 The scattered light is easily captured by the colorant particles 17. In addition, the second inorganic insulating particles 18 are the main factors that cause retroreflection as described above, but the coloring material particles 17 are better than the second inorganic insulating particles 18 because the coloring material particles 17 are smaller than the second inorganic insulating particles 18. And dispersed around the second inorganic insulating particles 18. Thereby, the coloring material particle | grains 17 can catch the incident light and reflected light of the 2nd inorganic insulating particle 18 effectively, and the reflected light from the 2nd inorganic insulating particle 18 can be reduced.

  Thus, the mounting structure 1 described above exhibits a desired function by driving or controlling the electronic component 2 in accordance with the power supply or signal supplied from the wiring board 3.

  Next, a method for manufacturing the mounting structure 1 described above will be described with reference to FIGS.

  (1) First, as shown in FIG. 4A, an inorganic insulating sol 21 containing first inorganic insulating particles 16, second inorganic insulating particles 18, a solvent and colorant particles 17, and a copper foil 22 are prepared. The inorganic insulating sol 21 is applied to one main surface of the copper foil 22.

  Examples of the solvent include organic solvents such as methanol, isopropanol, n-butanol, ethylene glycol, ethylene glycol monopropyl ether, methyl ethyl ketone, methyl isobutyl ketone, xylene, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, or dimethylacetamide. Can be used. Among them, it is desirable to use one containing methanol, isopropanol and / or propylene glycol monomethyl ether. As a result, the inorganic insulating sol 11x can be uniformly applied, and the solvent can be efficiently evaporated in a later step.

  The inorganic insulating sol 21 can be formed as follows, for example.

  First, after preparing the solution which mixed the solvent and the 1st inorganic insulating particle 16, the coloring material particle 17 is mixed and stirred in this solution. Thus, by dispersing the first inorganic insulating particles 16 in the solution in advance, when the colorant particles 17 are mixed and stirred in the solution, the first inorganic insulating particles 16 having a large specific surface area and a activated surface. However, it will agglomerate around the colorant particles 17 in an attempt to stabilize the surface, and the agglomeration of the colorant particles 9 dispersed by stirring can be satisfactorily reduced. Therefore, the first inorganic insulating particles 16 can be favorably arranged between the plurality of colorant particles 17. The solution is stirred, for example, by a ball mill for about 6 hours, so that the first inorganic insulating particles 16 are well arranged around the colorant particles 17. Moreover, it is preferable to arrange a hydroxyl group on the surface of the first inorganic insulating particles 16 with a silane coupling agent before mixing with the solvent. As a result, the affinity with the solvent is increased and it can be dispersed well in the solution.

  Next, the second inorganic insulating particles 18 are further mixed and stirred in the solution. As a result, after mixing the first inorganic insulating particles 16 and the colorant particles 17, the colorant particles 17 are mixed with the second inorganic insulating particles 18 larger than the particle diameter by mixing the second inorganic insulating particles 18. It can be arranged well around. The second inorganic insulating particles 18 can be satisfactorily stirred by performing, for example, a ball mill for 12 hours.

  Through the above steps, the inorganic insulating sol 21 can be formed.

  The inorganic insulating sol 21 may be formed as follows.

  First, in the same manner as described above, the solvent and the first inorganic insulating particles 16 are mixed to prepare a solution, and the colorant particles 17 are mixed and stirred in this solution. Next, the stirred solution is spray-dried to evaporate the solvent and produce a powder composed of the first inorganic insulating particles 16 and the colorant particles 17. Next, the inorganic insulating sol 21 is formed by mixing and stirring the powder, the solvent, and the second inorganic insulating particles 18.

  In this method, a powder composed of the first inorganic insulating particles 16 and the colorant particles 17 is produced. In this powder, the first inorganic insulating particles 16 surround the colorant particles 17, and the first inorganic insulating particles 16 and the colorant particles 17 are strongly bonded. As a result, when the powder, the solvent, and the second inorganic insulating particles are mixed and stirred, the bond between the first inorganic insulating particles 16 and the coloring material particles 17 can be maintained well, and the coloring material particles 17 can be maintained. The first inorganic insulating particles can be favorably disposed between the first inorganic insulating particles and the second inorganic insulating particles.

  The spray drying can be performed using, for example, a spray drying method. Specifically, the powder can be formed by spraying the solution in a granular form and heating at, for example, 100 ° C. to evaporate the solvent. Moreover, when mixing and stirring powder, a solvent, and the 2nd inorganic insulating particle 18, it is preferable to add the 1st inorganic insulating particle 16 newly and to stir. As a result, the first inorganic insulating particles 16 and the second inorganic insulating particles 18 can be satisfactorily bonded by mixing the first inorganic insulating particles 16 whose surface is newly activated.

  On the other hand, the inorganic insulating sol 21 can be applied to the copper foil 22 by using, for example, a dispenser, a bar coater, a die coater, or screen printing.

  (2) As shown in FIGS. 4B and 4C, after the solvent is evaporated, the inorganic insulating sol 21 is heated to bond the first inorganic insulating particles 16 to each other, and the first inorganic insulating particles 16. And the second inorganic insulating particles 18 are combined to form the inorganic insulating sol 21 as the inorganic insulating structure 14 to form a laminated sheet 23 having the copper foil 22 and the inorganic insulating structure 14.

  The inorganic insulating sol 21 is heated, for example, at 150 ° C. to 230 ° C. for 2 hours to completely dry the inorganic insulating sol 21 and the inorganic insulating particles are connected to each other through a neck structure. 14 is formed. Here, since the inorganic insulating sol 21 includes the first inorganic insulating particles 16 having a small particle size, the heating temperature of the inorganic insulating sol 21 is a low temperature that is lower than the crystallization start temperature of the first inorganic insulating particles 16. However, the inorganic insulating particles can be firmly bonded to each other.

  (3) As shown in FIG. 5A, a substrate precursor 24 is prepared. The substrate precursor 24 can be produced, for example, by laminating a plurality of resin sheets including an uncured resin and the substrate 12. In addition, uncured is a state of A-stage B-stage according to ISO472: 1999.

  (4) As shown in FIG. 5B, a laminated sheet 23 including the inorganic insulating structure 14 is laminated on the upper and lower surfaces of the substrate precursor 24 to form a laminated body 25, and the laminated body 25 is heated in the vertical direction. By applying pressure, the uncured resin of the substrate precursor 24 is thermally cured while filling the gaps in the network structure of the inorganic insulating structure 14. Thereby, the insulating layer 8 in which the inorganic insulating structure 14 is filled with the resin material 15 can be formed on both main surfaces of the base body 7.

  The temperature and pressure of the laminated body 25 are preferably set so that the temperature is higher than the curing start temperature of the substrate precursor 24 and lower than the thermal decomposition temperature. Specifically, the heat and pressure of the laminate 25 are set such that the temperature is set to 170 ° C. or higher and 230 ° C. or lower, the pressure is set to 2 MPa or higher and 3 MPa or lower, and the time is set to 0.5 hours or longer and 2 hours or shorter, for example. Is set. The curing start temperature is a temperature at which the resin becomes a C-stage according to ISO 472: 1999. The thermal decomposition temperature is a temperature at which the mass of the resin is reduced by 5% in the thermal mass measurement according to ISO11358: 1997.

  (5) As shown in FIG. 5 (c), a through-hole conductor 9 that penetrates the base 7 in the vertical direction is formed, and a conductive layer 13 is formed on the base 7. Specifically, this is performed as follows.

  First, a plurality of through holes T penetrating the base body 7 in the thickness direction are formed by, for example, drilling or laser processing. Next, a cylindrical through-hole conductor 9 is formed by depositing a conductive material on the inner wall of the through-hole T by, for example, electroless plating, vapor deposition, CVD, sputtering, or the like. Next, the inside of the cylindrical through-hole conductor 9 is filled with a resin material or the like to form the insulator 10. Next, a conductive material is deposited on the exposed portion of the insulator 10 by, for example, an electroless plating method, a vapor deposition method, a CVD method, or a sputtering method. Next, the conductive layer 13 having a wiring pattern shape is formed by patterning the copper foil 22 using a photolithography technique, etching, or the like.

  (6) The wiring pattern in the conductive layer 13 is inspected. The inspection of the wiring pattern can be performed by, for example, an optical automatic optical inspection device. Specifically, the wiring substrate 3 is irradiated with visible light, the reflected light is captured by a light receiving element such as a CCD, and the wiring portion (mainly made of copper) and the other portion (mainly made of resin) are imaged. Processing is performed to identify a difference in color tone to determine a wiring shape, and this is compared with design data to determine suitability.

  Here, as described above, since the insulating layer 6 includes the colorant particles 17, the reflection of visible light by the first inorganic insulating particles 16 and the second inorganic insulating particles 18 can be reduced. As a result, the wiring pattern can be inspected satisfactorily by improving the discrimination between the insulating layer 6 and the wiring pattern by the conductive layer 13.

  The core substrate 5 can be manufactured as described above.

  (7) As shown in FIG. 6A, similarly to the steps (1) and (2), the laminated sheet 23 having the copper foil 22 and the inorganic insulating structure 14 is formed, and an uncured resin material is formed. The adhesive layer precursor 26 made of is bonded onto the laminated sheet 23 via the inorganic insulating structure 14.

  The adhesive layer precursor 26 is bonded so as to be in contact with the inorganic insulating structure 14 by, for example, a vacuum laminator, a roll laminator, or a vacuum press. In the bonding step, the adhesive layer precursor 26 is heated by heating the adhesive layer precursor 26 in a temperature range (above the glass transition temperature of the resin and less than the polymerization start temperature) that is pressurized during the bonding and the resin is not thermally cured. The resin of the body 26 is fluidized, and the fluidized resin is filled into the gaps of the network structure of the inorganic insulating structure 14. In the adhesive layer precursor 26, the uncured resin filled in the gaps of the inorganic insulating structure 14 is cured in a later step to become the resin material 15 of the insulating layer 8.

(8) As shown in FIG. 6B, a laminated sheet 23 is laminated on each of the upper and lower surfaces of the core substrate 5 via an adhesive layer precursor 26, and the laminated body is heated and pressed in the vertical direction to bond. The layer precursor 26 is cured to form the adhesive layer 20. In addition, the heating and pressing of this laminated body is, for example, (4)
It can carry out similarly to the process of this.

  (9) As shown in FIG. 6C, the copper foil 22 is removed from the insulating layer 8 by an etching method using, for example, a mixed solution of sulfuric acid and hydrogen peroxide, a ferric chloride solution, a cupric chloride solution, or the like. Peel off.

  (10) As shown in FIG. 7A, the via conductor 19 that penetrates the second resin layer 22 and the insulating layer 8 in the vertical direction is formed, and the conductive layer 13 is formed on the insulating layer 8. Specifically, this is performed as follows.

  First, via holes V are formed in the second resin layer 22 and the insulating layer 8 by, for example, a YAG laser device or a carbon dioxide laser device, and at least a part of the conductive layer 13 is exposed in the via holes V. Next, the via conductor 19 is formed in the via hole V and the conductive layer 13 is formed on the insulating layer 8 by, for example, a semi-additive method, a subtractive method, or a full additive method.

  Note that after the conductive layer 13 is formed, the wiring pattern is inspected as in (5).

  (11) As shown in FIG. 7B, the build-up layers 6 are formed on the upper and lower surfaces of the core substrate 5 by repeating the steps (7) to (10). And the buildup layer 6 can be multilayered by repeating this process.

  The wiring board 3 can be produced as described above.

  (12) The mounting structure 1 shown in FIG. 1 can be manufactured by flip-chip mounting the electronic component 2 on the wiring board 3 via the bumps 4.

  It should be noted that the present invention is not limited to the above-described embodiments, and any embodiments to which changes are made without departing from the gist of the present invention are included in the scope of the present invention.

  For example, in the above-described embodiment of the present invention, the colorant particles made of an inorganic material are used, but the colorant particles made of an organic material may be used. In this case, as compared with the inorganic material, the molecules are actively moved by the π electrons of the organic material, so that the insulating layer can be colored more effectively.

  The organic material used for the colorant particles preferably includes a complex formed by coordinate bonding of a metal. As a result, when the ultraviolet rays are irradiated, the complex of the colorant particles absorbs the ultraviolet rays, so that the polymerization of the organic material of the colorant particles caused by the ultraviolet rays can be reduced satisfactorily. Therefore, discoloration of the colorant particles due to polymerization of the organic material can be reduced, so that uneven color of the insulating layer can be reduced. As such an organic material, copper phthalocyanine blue and copper phthalocyanine green can be used. In addition, when using what consists of organic materials as a coloring material particle, it is necessary to heat inorganic insulation sol below the decomposition temperature of the organic material which comprises a coloring material particle by the process of (2) mentioned above.

DESCRIPTION OF SYMBOLS 1 Mounting structure 2 Electronic component 3 Wiring board 4 Bump 5 Core board 6 Build-up layer 7 Base body 8 Insulating layer 9 Through-hole conductor 10 Insulator 11 Resin part 12 Base material 13 Conductive layer 14 Inorganic insulating structure 15 Resin material 16 1st DESCRIPTION OF SYMBOLS 1 Inorganic insulating particle 17 Colorant particle 18 2nd inorganic insulating particle 19 Via conductor 20 Adhesive layer 21 Inorganic insulating sol 22 Copper foil 23 Laminated sheet 24 Base | substrate precursor 25 Laminated body 26 Adhesive layer precursor

Claims (4)

An insulating layer and a conductive layer formed on the insulating layer;
Wherein the insulating layer is smaller particle size than the wavelength of visible light, and if Tsu even without least a plurality of partially connected to one another first inorganic insulating particles, the particle diameter is larger than the first inorganic insulating particles A plurality of colorant particles bonded to the first inorganic insulating particles with the first inorganic insulating particles interposed between each other, a particle size larger than the wavelength of visible light, and the first inorganic insulating particles A plurality of second inorganic insulating particles at least partially connected to each other through particles, and a resin material filled around the plurality of first and second inorganic insulating particles and the plurality of colorant particles. And the colorant particles have a particle size smaller than that of the second inorganic insulating particles . The wiring board according to claim 1 ,
The wiring substrate, wherein the atomic arrangement structure of the second inorganic insulating particles is amorphous. The wiring board according to claim 2 ,
The wiring board, wherein the first inorganic insulating particles and the colorant particles are made of an oxide. The wiring board according to claim 2 ,
The wiring board, wherein the colorant particles are made of an organic material.

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