JP5436247B2 - Wiring board - Google Patents

Description

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

  2. Description of the Related Art Conventionally, as a mounting structure in an electronic device, an electronic component mounted on a wiring board is used.

  Patent Document 1 describes a wiring board including an insulating substrate made of a resin and a circuit formed on the insulating substrate.

  Patent Document 2 describes a wiring board including a ceramic substrate and a wiring pattern formed on the ceramic substrate.

  By the way, an insulating substrate made of a resin has a high dielectric loss tangent, and the signal transmission characteristics of the circuit are liable to deteriorate.

  On the other hand, when the insulating substrate is a ceramic substrate, the ceramic substrate is easily cracked, and cracks are likely to occur when stress is applied to the ceramic substrate. Therefore, the circuit is disconnected from the crack, and thus the electrical reliability of the wiring substrate It is easy to deteriorate.

JP-A-8-116174 JP 2001-7524 A

  The present invention provides a wiring board that meets the demand for improving electrical characteristics and electrical reliability.

A wiring board according to an embodiment of the present invention includes a first and second inorganic insulating layers that are separated from each other in the thickness direction, and a first conductive layer that is partially formed between the first and second inorganic insulating layers. And a resin layer interposed between the first and second inorganic insulating layers and juxtaposed with the first conductive layer, wherein the first conductive layer has at least a part of one principal surface thereof The second inorganic insulating layer is in contact with the first inorganic insulating layer, at least a part of the other main surface is in contact with the second inorganic insulating layer, and the first conductive layer is formed on the other main surface with the second inorganic insulating layer. The plurality of second protrusions protruding at least partially in contact with the second inorganic insulating layer, and the resin layer partially including the first conductive layer and the second inorganic insulating layer. extends between, and is bonded to the first conductive layer and the second inorganic insulating layer with the extending portion is filled between the second convex portion That. A wiring board according to an aspect of the present invention includes a first and second inorganic insulating layers that are separated from each other in the thickness direction, and a first part that is partially formed between the first and second inorganic insulating layers. A conductive layer, and a resin layer interposed between the first and second inorganic insulating layers and juxtaposed with the first conductive layer, wherein the first conductive layer is at least part of one main surface. Is in contact with the first inorganic insulating layer, and at least part of the other main surface is in contact with the second inorganic insulating layer, and has a larger area in plan view than the first conductive layer. Or a second conductive layer that is a power supply wiring, wherein the first conductive layer is a signal wiring and is in contact with the sum of the contact area and the non-contact area with the second inorganic insulating layer. The ratio of the region is larger than that of the second conductive layer.

  According to the wiring board according to one aspect of the present invention, the first conductive layer has at least a part of one main surface in contact with the first inorganic insulating layer, and at least a part of the other main surface is the second inorganic insulating layer. In addition, since a resin layer disposed in parallel with the first conductive layer is interposed between the first and second inorganic insulating layers, the first conductive layer is improved in signal transmission characteristics while being improved. In addition, the stress applied to the second inorganic insulating layer can be relaxed, and as a result, a wiring board having excellent electrical characteristics and electrical reliability can be obtained.

It is sectional drawing which cut | disconnected the mounting structure concerning one Embodiment of this invention in the thickness direction. 2A is an enlarged cross-sectional view of the R1 portion of the mounting structure shown in FIG. 1, and FIG. 2B is a plan direction along line I-I in FIG. It is sectional drawing cut | disconnected by. 3A and 3B are cross-sectional views cut in the thickness direction for explaining the manufacturing process of the mounting structure shown in FIG. 1, and FIG. 3C shows the R2 portion of FIG. It is sectional drawing expanded. 4A to 4D are cross-sectional views cut in the thickness direction for explaining the manufacturing process of the mounting structure shown in FIG. 5A and 5B are cross-sectional views cut in the thickness direction for explaining the manufacturing process of the mounting structure shown in FIG. 1, and FIG. 5C shows the R3 portion of FIG. 5B. It is sectional drawing expanded. 6A is a cross-sectional view taken along the thickness direction for explaining the manufacturing process of the mounting structure shown in FIG. 1, and FIG. 6B is an enlarged view of a portion R4 in FIG. 6A. FIG. 7A and 7B 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 based on the drawings.

  The mounting structure 1 shown in FIG. 1 is used for electronic devices such as various audiovisual devices, home appliances, communication devices, computer devices, and peripheral devices thereof. The mounting structure 1 includes an electronic component 2 and a wiring board 3.

  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 conductive bumps 4 such as solder. The base material of the electronic component 2 is formed of a semiconductor material such as silicon, germanium, gallium arsenide, gallium arsenide phosphorus, gallium nitride, or silicon carbide. As the electronic component 2, one having a thickness of, for example, 0.1 mm or more and 1 mm or less can be used. The thickness is measured by observing the polished surface or fracture surface of the electronic component 2 with a scanning electron microscope, measuring the length along the thickness direction (Z direction) at 10 or more points, and calculating the average value. Is done.

  The wiring substrate 3 includes a core substrate 5 and a pair of wiring layers 6 formed above and below the core substrate 5.

  The core substrate 5 is intended to increase the rigidity of the wiring substrate 3 while achieving conduction between the pair of wiring layers 6 and has a thickness of 0.1 mm to 3.0 mm, for example. The core substrate 5 includes a base body 7, a through hole, a through hole conductor 8, and an insulator 9. The thickness is measured in the same manner as the electronic component 2.

  The base body 7 increases the rigidity of the core substrate 5, and includes a resin base body 10 and inorganic insulating layers 11 provided above and below the resin base body 10.

The resin base 10 is a main part of the base 7 and includes, for example, a resin material, a base material coated with the resin material, and an inorganic insulating filler contained in the resin material. The resin substrate 10 has a thickness set to, for example, 0.1 mm to 3.0 mm, a Young's modulus set to, for example, 0.2 GPa to 20 GPa, and a thermal expansion coefficient in the plane direction of, for example, 3 ppm / ° C. to 20 ppm / Set to ℃ or less, and the coefficient of thermal expansion in the thickness direction is, for example, 30 ppm / ℃ or more and 50p
It is set to pm / ° C. or lower, and the dielectric loss tangent is set to, for example, 0.01 to 0.02.

  The Young's modulus is measured using Nano Indentor XP / DCM manufactured by MTS Systems. The coefficient of thermal expansion is measured by a measuring method according to JISK7197-1991 using a commercially available TMA apparatus. The dielectric loss tangent is measured by a resonator method according to JIS R1627-1996.

  The resin material contained in the resin substrate 10 is a main part of the resin substrate 10, for example, epoxy resin, bismaleimide triazine resin, cyanate resin, polyparaphenylenebenzbisoxazole resin, wholly aromatic polyamide resin, polyimide resin. A resin material such as an aromatic liquid crystal polyester resin, a polyether ether ketone resin, or a polyether ketone resin can be used. The resin material has a Young's modulus set to, for example, 0.1 GPa or more and 5 GPa or less, and a coefficient of thermal expansion in a plane direction or a thickness direction set to, for example, 20 ppm / ° C. or more and 50 ppm / ° C. or less.

  The base material coated with the resin material increases the rigidity of the resin base 10 and has a smaller coefficient of thermal expansion in the plane direction (XY plane direction) than in the thickness direction (Z direction). The difference in the coefficient of thermal expansion in the plane direction with the component 2 can be reduced, and the warp of the wiring board 3 can be reduced. As the base material, a woven fabric or a non-woven fabric composed of fibers or a fiber in which fibers are arranged in one direction can be used. As the fibers, for example, glass fibers, resin fibers, carbon fibers, metal fibers, or the like are used. be able to.

  The inorganic insulating filler contained in the resin material reduces the coefficient of thermal expansion of the resin base 10 and increases the rigidity of the resin base 10, for example, silicon oxide, aluminum oxide, aluminum nitride, aluminum hydroxide, or carbonic acid. What was formed with inorganic insulating materials, such as calcium, can be used, a particle size is set as 0.5 micrometer or more and 5.0 micrometers or less, for example, and a coefficient of thermal expansion is set as 0 ppm / degrees C or more and 15 ppm / degrees C or less, for example. The content of the resin substrate 10 in the resin material is set to, for example, 3 volume% or more and 60 volume% or less.

  The particle size of the inorganic insulating filler was measured by observing the polished surface or fractured surface of the resin substrate 10 with a field emission electron microscope, and photographing an enlarged cross section so as to include particles of 20 particles or more and 50 particles or less, It is measured by measuring the maximum diameter of each particle in the enlarged cross section. Further, the content (volume%) of the inorganic insulating filler in the resin portion of the resin substrate 10 is obtained by photographing the polished surface of the resin substrate 10 with a field emission electron microscope and using an image analyzer or the like. It is measured by measuring the area ratio (area%) of the inorganic insulating filler in the part at 10 cross-sections, calculating the average value of the measured values, and regarding the content (volume%).

  The inorganic insulating layer 11 includes an inorganic insulating material as a main part, and the inorganic insulating material has a low dielectric loss tangent, a low coefficient of thermal expansion, a high rigidity, and a high insulating property as compared with the resin material. It has a function of having a low coefficient of thermal expansion, high rigidity and high insulation.

  Therefore, the inorganic insulating layer 11 can improve the signal transmission characteristics of the wiring layer 6 formed on the substrate 7 by reducing the dielectric loss tangent of the substrate 7. Moreover, the curvature of the wiring board 3 can be reduced by reducing the thermal expansion coefficient in the plane direction of the base body 7, and the base body 7 and the through-hole conductor can be reduced by reducing the thermal expansion coefficient in the thickness direction of the base body 7. As a result, disconnection of the through-hole conductor 8 due to the difference in thermal expansion coefficient with respect to 8 can be reduced. Further, by increasing the rigidity of the substrate 7, the rigidity can be increased without increasing the thickness of the wiring board 3. Further, by increasing the insulating property of the base body 7, a short circuit between the pair of wiring layers 6 disposed on the upper and lower surfaces of the core substrate 5 can be reduced.

  Note that the inorganic insulating layer 11 includes an inorganic insulating portion mainly composed of an inorganic insulating material and a void formed in the inorganic insulating portion (not shown), and a part of the resin base 10 disposed in the void. A certain resin portion may be included. In this case, since the resin material has a lower Young's modulus compared to the inorganic insulating material, the stress applied to the inorganic insulating portion is relaxed, and the occurrence of cracks in the inorganic insulating portion due to the stress is reduced.

  The inorganic insulating layer 11 includes, for example, an inorganic insulating part of 85% by volume or more and 100% by volume or less, and when including a resin part, the inorganic insulating layer 11 includes a resin part of 0.2% by volume or more and 15% by volume or less. In addition, the inorganic insulating layer 11 is formed, for example, in a flat plate shape, and the thickness is set to, for example, 3 μm or more and 100 μm or less, and the thickness is set to, for example, 3% or more and 10% or less of the resin substrate 10. The inorganic insulating layer 11 has a Young's modulus set to, for example, 2 GPa or more and 100 GPa or less, a coefficient of thermal expansion in a thickness direction or a plane direction, for example, set to 0 ppm / ° C. or more and 30 ppm / ° C. or less, It is set to 0001 or more and 0.02 or less.

  As the inorganic insulating part, for example, those formed of an inorganic insulating material such as silicon oxide, aluminum oxide, titanium oxide, magnesium oxide, or zirconium oxide can be used, and in particular, from the viewpoint of low dielectric loss tangent and low thermal expansion coefficient. It is desirable to use silicon oxide.

  In addition, it is desirable that the inorganic insulating portion is in an amorphous (amorphous) state. As a result, in the inorganic insulating layer 11, the anisotropy of the thermal expansion coefficient due to the crystal structure can be reduced. Therefore, when the wiring board 3 is heated, when the wiring board 3 is heated, During cooling, the shrinkage of the inorganic insulating layer 11 can be made more uniform in each direction, and the generation of cracks in the inorganic insulating layer 11 can be reduced.

  As the amorphous inorganic insulating material, for example, silicon oxide can be used, and the region of the crystal phase is set to, for example, less than 10% by volume, and more preferably set to less than 5% by volume. Note that the volume ratio of the crystalline phase region in the inorganic insulating material was determined by mixing the 100% crystallized sample powder with the amorphous powder and measuring it by the X-ray diffraction method to create a calibration curve. Measured by comparing line data.

  In addition, the inorganic insulating portion includes, for example, 97% by volume or more and 100% by volume or less of the inorganic insulating material, and includes a resin material and voids of more than 0% by volume and 3% by volume or less when including the remainder other than the inorganic insulating material.

  The inorganic insulating part has a Young's modulus set to, for example, 10 GPa or more and 100 GPa or less, a Young's modulus set to 1.2 to 5 times that of the resin substrate 10, and the thermal expansion coefficient in the thickness direction and the plane direction is, for example, It is set to 0 ppm / ° C. or more and 10 ppm / ° C. or less, the coefficient of thermal expansion in the thickness direction and the plane direction is set to 0.001 times or more and 0.5 times or less of the resin substrate 10, and the dielectric loss tangent is, for example, 0.0001 or more The dielectric loss tangent is set to be 0.01 times or more and 0.5 times or less of the resin substrate 10, for example.

  As the inorganic insulating part, for example, those formed of an inorganic insulating material such as silicon oxide, aluminum oxide, titanium oxide, magnesium oxide, or zirconium oxide can be used, and in particular, from the viewpoint of low dielectric loss tangent and low thermal expansion coefficient. It is desirable to use silicon oxide. In addition, the inorganic insulating portion includes, for example, 97% by volume or more and 100% by volume or less of the inorganic insulating material, and includes a resin material and voids of more than 0% by volume and 3% by volume or less when including the remainder other than the inorganic insulating material.

  Further, as shown in FIG. 2A, the inorganic insulating portion includes, for example, first inorganic insulating particles 11n bonded to each other, and the first inorganic insulating particles 11n have a particle size set to, for example, 3 nm or more and 110 nm or less. Yes. As a result, since the particle diameter of the first inorganic insulating particles 11n is set to 110 nm or less, the adhesive strength of the first inorganic insulating particles 11n can be increased as will be described later.

  The inorganic insulating part may include second inorganic insulating particles 11m that are larger in particle size than the first inorganic insulating particles 11n and bonded to each other via the first inorganic insulating particles 11n. As a result, since the second inorganic insulating particles 11m have a larger particle size than the first inorganic insulating particles 11n, it is possible to suppress the extension of cracks generated in the inorganic insulating portion. The particle diameter of the second inorganic insulating particles 11m is set to, for example, 0.5 μm or more and 5 μm or less.

  As the first inorganic insulating particles 11n and the second inorganic insulating particles 11m, those formed by the inorganic insulating material constituting the inorganic insulating portion described above can be used, and it is desirable that they are made of the same material. The first inorganic insulating particles 11n and the second inorganic insulating particles 11m are preferably spherical.

  The first inorganic insulating particles 11n and the second inorganic insulating particles 11m are confirmed by observing the polished surface or fracture surface of the inorganic insulating layer 11 with a field emission electron microscope. The particle diameters of the first inorganic insulating particles 11n and the second inorganic insulating particles 11m are determined by observing the polished surface or the fractured surface of the inorganic insulating layer 11 with a field emission electron microscope. It is measured by photographing a cross section enlarged so as to include a particle, and measuring the maximum diameter of each particle in the enlarged cross section.

  The above-described base body 7 is provided with a through hole that penetrates the base body 7 in the thickness direction and has a cylindrical shape with a diameter of 0.1 mm to 1 mm, for example. Inside the through-hole, a through-hole conductor 8 that electrically connects the upper and lower wiring layers 6 of the core substrate 5 is formed in a cylindrical shape along the inner wall of the through-hole. As this through-hole conductor 8, for example, a conductor formed of a conductive material such as copper, silver, gold, aluminum, nickel, or chromium can be used, and the coefficient of thermal expansion is, for example, 14 ppm / ° C. or more and 18 ppm / ° C. or less. Is set.

  In the hollow portion of the through-hole conductor 8 formed in a cylindrical shape, an insulator 9 is formed in a columnar shape, and a support surface of a via conductor 14 to be described later is formed by an end surface of the through-hole conductor 8 and an end surface of the insulator 9. Is forming. As the insulator 9, what was formed with resin materials, such as a polyimide resin, an acrylic resin, an epoxy resin, cyanate resin, a fluororesin, a silicon resin, a polyphenylene ether resin, or a bismaleimide triazine resin, can be used, for example.

  On the other hand, a pair of wiring layers 6 are formed on the upper and lower surfaces of the core substrate 5 as described above. The wiring layer 6 includes a resin layer 12, an inorganic insulating layer 11, a conductive layer 13, a via hole, and a via conductor 14. The conductive layer 13 and the via conductor 14 are electrically connected to each other, and constitute a wiring portion including a ground wiring, a power supply wiring, and / or a signal wiring.

  The resin layer 12 includes a resin material as a main part, and is interposed between the inorganic insulating layers 11 adjacent to each other in the thickness direction as shown in FIGS. 2A and 2B, and on the conductive layer 13 side. The conductive layers 13 are arranged in parallel to each other and spaced apart in the plane direction, and are bonded to the main surfaces of the inorganic insulating layers 11 adjacent to the thickness direction and the side surfaces of the conductive layers 13.

Therefore, since the resin layer 12 is interposed between the inorganic insulating layers 11 adjacent to each other in the thickness direction, the resin material has higher elasticity than the inorganic insulating material, so that stress is applied to the wiring board 3. In this case, the resin layer 12 is deformed, and the stress applied to the inorganic insulating layer 11 can be relaxed. Therefore, it is possible to reduce the cracks in the inorganic insulating layer 11, reduce the disconnection of the first conductive layer 13 a due to the cracks, and thus obtain the wiring substrate 3 excellent in electrical reliability.

  Moreover, the resin layer 12 can suppress a short circuit between the conductive layers 13 by being interposed between the conductive layers 13 separated along the planar direction. Moreover, the inorganic insulating layers 11 can be bonded to each other by bonding to both of the adjacent inorganic insulating layers 11. Further, by adhering to the main surface of the inorganic insulating layer 11 and the side surface of the conductive layer 13, the adhesive strength between the conductive layer 13 and the first resin adhesive layer 12a can be increased.

  The resin layer 12 includes, for example, a resin material and an inorganic insulating filler contained in the resin material. The thickness is set to, for example, 3 μm or more and 20 μm or less, and the thickness is, for example, 0.4 times that of the inorganic insulating layer 11. The Young's modulus is set to, for example, 0.2 GPa to 20 GPa, the Young's modulus is set to, for example, 0.01 times to 0.6 times that of the inorganic insulating layer 11, and the dielectric loss tangent is, for example, 0 .001 or more and 0.02 or less, the dielectric loss tangent is set to 4 to 10 times that of the inorganic insulating layer 11, and the coefficient of thermal expansion in the plane direction and the thickness direction is, for example, 20 to 50 ppm / ° C. The coefficient of thermal expansion in the plane direction and the thickness direction is set to, for example, 2 to 10 times that of the inorganic insulating layer 11.

  The resin material contained in the resin layer 12 is, 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. Alternatively, a resin material such as polyetherketone resin can be used. The resin material has a Young's modulus set to, for example, 0.1 GPa or more and 5 GPa or less, and a coefficient of thermal expansion in a plane direction or a thickness direction set to, for example, 20 ppm / ° C. or more and 50 ppm / ° C. or less.

  The inorganic insulating filler can be the same as the inorganic insulating filler contained in the resin base 10 described above, and among them, it is desirable to use the same material as the inorganic insulating filler contained in the resin base 10.

  The inorganic insulating layer 11 included in the wiring layer 6 is formed on the resin layer 12 and has the same function as that of the inorganic insulating layer 11 included in the substrate 7 described above, and the thickness is set to, for example, 3 μm or more and 30 μm or less. The thickness is set to 0.5 times or more and 10 times or less of the resin layer 12, for example. Moreover, when the resin part is formed, this resin part is a part of resin layer 12, for example.

  Other configurations of the inorganic insulating layer 11 are the same as those of the inorganic insulating layer 11 included in the substrate 7 described above.

  The conductive layer 13 functions as a ground wiring, a power supply wiring, or a signal wiring, is formed on the inorganic insulating layer 11, and is separated from each other in the thickness direction via the inorganic insulating layer 11. . As the conductive layer 13, for example, a layer formed of a metal material such as copper, silver, gold, aluminum, nickel, or chromium can be used. The thickness is set to 3 μm or more and 20 μm or less, and the thermal expansion coefficient is, for example, 14 ppm. / ° C. or more and 18 ppm / ° C. or less.

  The conductive layer 13 is partially formed between the adjacent inorganic insulating layers 11, and the resin layer 12 is arranged in parallel. Therefore, as compared with the case where the conductive layer 13 is formed inside the inorganic insulating layer 11, the volume of the inorganic insulating layer 11 in the wiring substrate 3 can be increased, so that the wiring substrate 3 is made to have a lower dielectric loss tangent and lower thermal expansion. And high rigidity.

  The via conductor 14 connects the conductive layers 13 that are spaced apart from each other in the thickness direction, and is formed in a columnar shape that becomes narrower toward the core substrate 5. As the via conductor 14, for example, a conductor formed of a conductive material such as copper, silver, gold, aluminum, nickel, or chromium can be used, and the coefficient of thermal expansion is set to, for example, 14 ppm / ° C. or more and 18 ppm / ° C. or less. Yes.

  Here, in the wiring substrate 3 of this embodiment, the inorganic insulating layer 11 is formed on the resin substrate 10 as the first inorganic insulating layer 11a, and the first inorganic insulating layer 11a is interposed through the resin layer 12. In contrast, a layer separated along the thickness direction is defined as a second inorganic layer 11b.

  The conductive layer 13 is formed on the base body 7 and connected to the through-hole conductor 8 as the first conductive layer 13a, and the conductive layer 13 spaced apart from the first conductive layer 13a in the planar direction is the first conductive layer 13a. The second conductive layer 13b is separated from the first conductive layer 13a in the thickness direction via the second inorganic insulating layer 11b, and is defined as the third conductive layer 13c.

  On the other hand, in the wiring substrate 3 of the present embodiment, as shown in FIG. 2A, the first conductive layer 13a has at least a part of one main surface in contact with the first inorganic insulating layer 11a and the other main layer. At least a part of the surface is in contact with the second inorganic insulating layer. Therefore, since the inorganic insulating material has a low dielectric loss tangent as compared with the resin material, the first conductive layer 13a is brought into contact with the first inorganic insulating layer 11a and the second inorganic insulating layer 11b to thereby provide the first conductive layer. It is possible to obtain the wiring board 3 with improved signal transmission characteristics of the layer 13a and thus excellent electrical characteristics. The presence or absence of such contact can be observed by an electron micrograph of a cross section obtained by cutting the wiring board 3 in the thickness direction.

  In addition, the first conductive layer 13a has a plurality of first protrusions 15a that protrude toward the first inorganic insulating layer 11a on one main surface and at least a part of which is in contact with the first inorganic insulating layer 11a. Part of the first inorganic insulating layer 11a is filled between the first protrusions 15a. Therefore, the contact area between the first conductive layer 13a and the first inorganic insulating layer 11a can be increased, and the signal transmission characteristics of the first conductive layer 13a can be enhanced.

  Further, the first conductive layer 13a has a plurality of second convex portions 15b that protrude toward the second inorganic insulating layer 11b on the other main surface and at least part of which is in contact with the second inorganic insulating layer 11b. A part of the resin layer 12 extends between the first conductive layer 13a and the second inorganic insulating layer 11b, and the extended portion 12a is filled between the second convex portions 15b and the first conductive layer 13a. And bonded to the second inorganic insulating layer 11b.

  Therefore, the extending portion 12a is bonded to the first conductive layer 13a and the second inorganic insulating layer 11b, thereby increasing the adhesive strength between the first conductive layer 13a and the second inorganic insulating layer 11b and reducing the elasticity. By filling the extended portion 12a between the second convex portions 15b, cracks in the thickness direction generated at the boundary between the first conductive layer 13a and the second inorganic insulating layer 11b can be reduced.

  The first conductive layer 13a is a signal wiring, and the second conductive layer 13b is a ground wiring or power supply wiring having a larger area in plan view than the first conductive layer 13a. In the layer 13a, the ratio of the contact area to the sum of the contact area and the non-contact area with the second inorganic insulating layer 11b (hereinafter referred to as the contact area ratio) is larger than that of the second conductive layer 13b. As a result, in the first conductive layer 13a, the signal transmission characteristics are improved by increasing the contact area with the second inorganic insulating layer 11b, and in the second conductive layer 13b, the adhesion area of the extending portion 11a is increased. By doing so, peeling between the second conductive layer 13b and the second inorganic insulating layer 11b can be reduced.

The area of the second conductive layer 13b in plan view is set to be, for example, 10 times or more and 20 times or less of the first conductive layer 13a. The first conductive layer 13a has a contact area ratio (first contact area ratio) with the second inorganic insulating layer 11b set to, for example, 30% or more and 90% or less, and the second conductive layer 13b The contact area ratio (second contact area ratio) with the second inorganic insulating layer 11b is set to, for example, 0% to 40%. Further, the first contact area ratio is set to be 1.8 times or more and 2.2 times or less of the second contact area ratio, for example. The contact area ratio is determined by observing an electron micrograph of a cross section obtained by cutting the wiring board 3 in the thickness direction, and the length of the contact part (contact area) at the interface and the non-contact part (non-contact). The area is calculated by measuring 10 or more locations.

  Moreover, as for the 1st conductive layer 13a, it is desirable that the area of one main surface is larger than the area of a side surface. As a result, the contact area between the first conductive layer 13a and the first inorganic insulating layer 11a can be increased, and the signal transmission characteristics of the first conductive layer 13a can be enhanced. The first conductive layer 13a has an area of one main surface set to, for example, 1.2 times to 10 times the side surface.

  The via conductor 14 penetrates the second inorganic insulating layer 11b in the thickness direction, and is electrically connected to the first conductive layer 13a and the third conductive layer 13c. Therefore, the via conductor 14 can be brought into contact with the second inorganic insulating layer 11b, and the signal transmission characteristics of the via conductor 14 can be improved.

  Thus, the mounting structure 1 described above exhibits a desired function by driving or controlling the electronic component 2 based on the power and signals supplied via the wiring board 3.

  Next, the manufacturing method of the mounting structure 1 mentioned above is demonstrated based on FIGS.

(Preparation of laminated plate 16)
(1) As shown in FIG. 3A, a copper foil 13x and an inorganic insulating sol 11x containing a first inorganic insulating particle 11n, a second inorganic insulating particle 11m, and a solvent are prepared. An inorganic insulating sol 11x is applied to the main surface.

  For example, the copper foil 13x is roughened by an etchant whose main surface is mainly composed of an organic acid such as formic acid, thereby forming irregularities.

  The inorganic insulating sol 11x includes a solid content and a solvent. The inorganic insulating sol 11x preferably contains 5% to 50% by volume of solid content and 50% to 95% by volume of solvent. As a result, by containing 50% by volume or more of the solvent in the inorganic insulating sol 11x, the viscosity of the inorganic insulating sol 11x is reduced, the flatness of the upper surface of the inorganic insulating layer 11 is improved, and the flatness of the upper surface of the wiring substrate 3 is increased. Can be improved. Moreover, productivity of the inorganic insulating layer 11 can be improved by increasing the amount of solid components of the inorganic insulating sol 11x by including 95% by volume or less of the solvent in the inorganic insulating sol 11x. Further, it is desirable that the solid content includes 5% to 50% by volume of the first inorganic insulating particles 11n and 50% to 95% by volume of the second inorganic insulating particles 11m.

  The first inorganic insulating particles 11n having a small particle size are obtained by purifying a silicate compound such as a silicate compound such as a sodium silicate aqueous solution (water glass) and chemically depositing silicon oxide by a method such as hydrolysis. Can be produced. Moreover, by producing in this way, crystallization of the 1st inorganic insulating particle 11n can be suppressed and an amorphous state can be maintained. In addition, when produced in this way, the 1st inorganic insulating particle 11n may contain 1 ppm or more and 5000 ppm or less of impurities, such as sodium oxide.

  In addition, the particle diameter of the first inorganic insulating particles 11n is desirably set to 3 nm or more. As a result, the viscosity of the inorganic insulating sol 11x can be reduced and the flatness of the upper surface of the inorganic insulating layer 11 can be improved.

  The second inorganic insulating particle 11m having a large particle size is formed by, for example, purifying a silicate compound such as an aqueous sodium silicate solution (water glass) and spraying a solution in which silicon oxide is chemically deposited in a flame to It can be manufactured by heating to 800 ° C. or higher and 1500 ° C. or lower while suppressing formation. Here, since the second inorganic insulating particles 11m can be easily produced by heating at a high temperature while reducing the formation of aggregates as compared with the first inorganic insulating particles 11n, the second inorganic insulating particles 11m. Is produced by heating at a high temperature, the hardness of the second inorganic insulating particles 11m can be more easily increased than that of the first inorganic insulating particles 11n.

  In addition, as for the heating time at the time of producing the 2nd inorganic insulating particle 11m, it is desirable to set to 1 second or more and 180 seconds or less. As a result, by shortening the heating time, the crystallization of the second inorganic insulating particles 11m can be suppressed and the amorphous state can be maintained even when heated to 800 ° C. or higher and 1500 ° C. or lower.

  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. Things can be used. Among these, it is desirable to use one containing methanol, isopropanol 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 the step (2).

  The inorganic insulating sol 11x can be applied using, for example, a dispenser, a bar coater, a die coater, or screen printing.

  The inorganic insulating sol 11x applied to one main surface of the copper foil 13x is formed in a flat plate shape, and the thickness after drying is set to, for example, 3 μm or more and 110 μm or less.

  (2) As shown in FIGS. 3B and 3C, after drying the inorganic insulating sol 11x and evaporating the solvent, the solid content of the inorganic insulating sol 11x is heated to form the first inorganic insulating particles 11n. And the first inorganic insulating particles 11n and the second inorganic insulating particles 11m are combined to make the inorganic insulating sol 11x as an inorganic insulating portion of the inorganic insulating layer 11, so that the copper foil 13x and the inorganic insulating layer 11 are formed. The laminated sheet 17 containing is formed.

  Here, when the solid content of the inorganic insulating sol 11x is heated, the first inorganic insulating particles 11n having a small particle size and easily bonded to each other are bonded to each other, and the first inorganic insulating particles 11n and the second inorganic insulating particles 11m are combined. Because of the bonding, the second inorganic insulating particles 11m having a large particle size and difficult to bond can be bonded to each other through the first inorganic insulating particles 11n, and the highly rigid inorganic insulating layer 11 can be formed.

  Further, in the step (1), when an unevenness is formed on one main surface of the copper foil 13x, the inorganic insulating layer 11 is formed along the unevenness, so that the inorganic insulating layer 11 has a copper foil 13x side. While forming the 1st convex part 15a in a main surface, a part of inorganic insulating layer 11 can be filled between this 1st convex part 15a.

The inorganic insulating sol 11x is dried by, for example, heating and air drying, and the temperature is set to 20 ° C. or higher and lower than the boiling point of the solvent (the boiling point of the lowest boiling point when two or more solvents are mixed). It is desirable that the drying time is set to 20 seconds or more and 30 minutes or less. As a result, the filling density of the second inorganic insulating particles 11m can be increased by reducing the boiling of the solvent.

  In addition, when evaporating the solvent, since the solvent has good wettability with the second inorganic insulating particles 11m, the solvent tends to remain at the proximity point between the second inorganic insulating particles 11m. As a result, since the first inorganic insulating particles 11n move to the proximity point as the solvent moves to the proximity point, the first inorganic insulating particles 11n are interposed between the second inorganic insulating particles 11m. Can do.

  Further, since the solvent evaporates more in the region including the first inorganic insulating particles 11n having a small particle size than in the region including the second inorganic insulating particles 11m having a large particle size, the first inorganic insulating particles 11n and the second A void surrounded by the inorganic insulating particles 11m can be formed.

  The heating of the inorganic insulating sol 11x is desirably set to a temperature not lower than the boiling point of the solvent and not higher than a crystallization start temperature of the first inorganic insulating particles 11n and the second inorganic insulating particles 11m. As a result, when the heating temperature is equal to or higher than the boiling point of the solvent, the remaining solvent can be efficiently evaporated. Further, the heating temperature is lower than the crystallization start temperature of the first inorganic insulating particles 11n and the second inorganic insulating particles 11m, thereby reducing the crystallization of the first inorganic insulating particles 11n and the second inorganic insulating particles 11m. The ratio of the amorphous state can be increased. As a result, in the inorganic insulating layer 11, cracks caused by phase transition accompanying crystallization can be reduced. In particular, when silicon oxide is used as the inorganic insulating material of the first inorganic insulating particles 11n and the second inorganic insulating particles 11m, crystallization of the first inorganic insulating particles 11n can be effectively reduced. Note that the crystallization start temperature is a temperature at which the amorphous inorganic insulating material starts to crystallize, that is, a temperature at which the volume of the crystal phase region increases. For example, the crystallization start temperature of silicon oxide is about 1300 ° C.

  In addition, as for the heating of the inorganic insulating sol 11x, it is desirable that the temperature is set to 100 degrees or more and less than 600 degrees, and the time is set to 0.5 hours or more and 24 hours or less, for example. The inorganic insulating sol 11x can be heated, for example, in an air atmosphere. When the temperature is raised to 150 ° C. or higher, it is desirable that the inorganic insulating sol 11x is heated in an inert atmosphere such as vacuum or argon or a nitrogen atmosphere in order to suppress oxidation of the copper foil 13x.

  On the other hand, the particle diameter of the first inorganic insulating particles 11n before heating the inorganic insulating sol 11x is preferably set to 110 nm or less, particularly 50 nm or less. As a result, even if the heating temperature of the inorganic insulating sol 11x is lower than the crystallization start temperature of the first inorganic insulating particle 11n and the thermal decomposition temperature of the first resin adhesive layer 12a, the first inorganic insulating particles 11n Can be firmly bonded. This is because the first inorganic insulating particles 11n have an extremely small particle size of 110 nm or less, and the atoms of the first inorganic insulating particles 11n, particularly the atoms on the surface, actively move. It is estimated that 1 inorganic insulating particle 11n couple | bonds firmly.

  In addition, by setting the particle diameter of the first inorganic insulating particles 11n to be smaller, the first inorganic insulating particles 11n can be firmly bonded to each other at a lower temperature. The temperature at which the first inorganic insulating particles 11n can be firmly bonded to each other is, for example, about 250 ° C. when the particle size is set to 110 nm or less, and 150 ° C. when the particle size is set to 50 nm or less. Degree.

  In addition, the solid content of the inorganic insulating sol 11x desirably includes 5% by volume or more of the first inorganic insulating particles 11n. As a result, the amount of the first inorganic insulating particles 11n interposed between the adjacent points of the second inorganic insulating particles 11m is secured, and the area where the second inorganic insulating particles 11m are in contact with each other is reduced, thereby Stiffness can be increased.

  The laminated sheet 17 can be formed as described above.

  (3) As shown in FIG. 4A, a resin base precursor 10x is prepared. The resin base precursor 10x can be produced, for example, by laminating a plurality of resin sheets including an uncured resin and a base material. The uncured state is an A-stage or B-stage according to ISO 472: 1999.

  (4) As shown in FIGS. 4B and 4C, a laminated sheet 17 is laminated on each of the upper and lower surfaces of the resin substrate precursor 10x via the inorganic insulating layer 11, and the laminated body is vertically oriented. By applying heat and pressure, the resin substrate precursor 10x is thermally cured to form the resin substrate 10, and the laminated plate 16 including the inorganic insulating layers 11 on and below the resin substrate 10 is formed.

  It is desirable that the heat and pressure of the laminate is set to a temperature not lower than the thermal decomposition temperature of the resin substrate 10 and lower than the thermal decomposition temperature. Specifically, the heat and pressure of the laminate is 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 10 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.

  In addition, since the resin base precursor 10x softens and flows when the laminated body is heated and pressed, the laminated board 16 having excellent flatness can be formed by, for example, heating and pressing with a flat metal plate. .

  Further, when the laminate is heated and pressurized, the resin substrate precursor 10x is softened and fluidized, and a part of the resin substrate precursor 10x is filled into the voids of the inorganic insulating layer 11 through the openings, and the resin substrate A resin part can be formed by thermosetting a part of the precursor 10x. As a result, the insulating property of the inorganic insulating layer 11 can be enhanced by filling a part of the resin base precursor 10x in the gap.

  The laminated board 16 can be produced as described above.

(Preparation of core substrate 5)
(5) As shown in FIG. 4 (d), a through-hole conductor 8 that penetrates the base body 7 in the vertical direction is formed, and a conductive layer 13 is formed on the base body 7. Specifically, this is performed as follows.

  First, a plurality of through holes penetrating the base body 7 in the thickness direction are formed by, for example, drilling or laser processing. Next, a cylindrical through-hole conductor 8 is formed by depositing a conductive material on the inner wall of the through-hole by, for example, electroless plating, vapor deposition, CVD, sputtering, or the like. Next, the inside of the cylindrical through-hole conductor 8 is filled with a resin material or the like to form an insulator 9. Next, a conductive material is deposited on the exposed portion of the insulator 9 by, for example, electroless plating, vapor deposition, CVD, sputtering, or the like. Next, the conductive layer 13 is formed by patterning the copper foil 13x using a photolithography technique, etching, or the like.

  By forming the conductive layer 13 in this manner, at least a part of one main surface of the conductive layer 13 (first conductive layer 13a) can be brought into contact with the inorganic insulating layer 11 (first inorganic insulating layer 11a). .

  In addition, the conductive layer 13 is preferably formed by patterning, and then the surface is roughened by an etching solution mainly containing an organic acid such as formic acid. As a result, the second convex portion 15b is formed.

  The core substrate 5 can be manufactured as described above.

(Preparation of wiring board 3)
(6) As shown in FIG. 5A, after forming the laminated sheet 17 having the copper foil 13x and the inorganic insulating layer 11x as in the steps (1) to (2), the uncured resin layer precursor is formed. The body 12x is placed on the laminated sheet 17 via the inorganic insulating layer 11x.

  (7) As shown in FIGS. 5 (b) and 5 (c) and FIGS. 6 (a) and 6 (b), the laminated sheet 17 is placed on the upper and lower surfaces of the core substrate 5 via the resin layer precursor 12x. By laminating and heating and pressing the laminated body in the vertical direction, the resin layer precursor 12x is thermally cured to form the resin layer 12, and the resin layer 12 and the inorganic insulating layer 11 are formed above and below the core substrate 5.

  Here, when the laminated body is heated and pressurized in the vertical direction, the resin layer precursor 12x between the inorganic insulating layer 11 (second inorganic insulating layer 11b) and the first conductive layer 13a of the laminated sheet 17 by the heating. And the resin layer precursor 12x is moved between the conductive layers 13 on the core substrate 5 by the pressurization, whereby the second inorganic insulating layer 11b is made at least part of the first conductive layer 13a. It can be made to contact. In addition, the contact area ratio of the first conductive layer 13a with the second inorganic insulating layer 11b is determined by appropriately determining the thickness of the resin layer precursor 12x, the pressure at the time of heating and pressing, the hardness of the pressing member used for pressing, or the like. It can be adjusted by adjusting.

  Further, when the laminated sheet 17 is laminated on each of the upper and lower surfaces of the core substrate 5, a gap is formed between the second convex portions 15b, so that when the laminated body is heated and pressurized in the vertical direction, it softened and flows. The extending part 12a can be formed by moving the resin layer precursor 12x into the gap.

  In addition, since the softened and fluidized resin layer precursor 12x is likely to remain on the second conductive layer 13b having a large area in plan view when the laminate is heated and pressurized, the second conductive layer 13b includes the second conductive layer 13b. The contact area ratio with the inorganic insulating layer 11b can be increased.

  Further, when the laminated body is heated and pressurized, the resin layer precursor 12x is softened and fluidized, and a part of the resin layer precursor 12x is filled into the voids of the inorganic insulating portion through the openings. A resin part can be formed by thermosetting a part of the precursor 12x.

  In addition, the heating and pressurization of this laminated body can be performed similarly to the process of (4), for example.

  (8) As shown in FIG. 7A, a via conductor 14 that penetrates the resin layer 12, the inorganic insulating layer 11 and the copper foil 13x in the vertical direction is formed, and the conductive layer 13 is formed on the first resin adhesive layer 12a. Form. Specifically, this is performed as follows.

  First, via holes are formed in the resin layer 12, the inorganic insulating layer 11 (second inorganic insulating layer 11b), and the copper foil 13x by, for example, a YAG laser device or a carbon dioxide gas laser device, and the conductive layer 13 (first layer) is formed in the via hole. At least part of the conductive layer 13a) is exposed. Next, the via conductor 14 is formed in the via hole and the conductive layer 13 is formed on the inorganic insulating layer 11 by, for example, a semi-additive method or a subtractive method.

  Here, when forming the via hole on the first conductive layer 13a, since at least a part of the first conductive layer 13a is in contact with the second inorganic insulating layer 11b, the resin layer 12 through which the via hole passes is formed. Can be reduced. As a result, since the residue of the resin material remaining in the via hole can be reduced, the connection reliability between the first conductive layer 13a and the via conductor 14 can be improved.

  (9) As shown in FIG. 7B, the wiring layers 6 are formed above and below the core substrate 5 by repeating the steps (6) to (8). Note that the wiring layer 6 can be made more multilayered by repeating this step.

  The wiring board 3 can be produced as described above.

(Production of mounting structure 1)
(10) By mounting the electronic component 2 on the wiring substrate 3 via the bumps 4 by flip chip mounting, the mounting structure 1 shown in FIG. 1 can be manufactured.

  The present invention is not limited to the above-described embodiments, and various modifications, improvements, combinations, and the like can be made without departing from the spirit of the present invention.

  For example, in the above-described embodiment of the present invention, the configuration in which the resin layer and the inorganic insulating layer are each laminated in the wiring layer has been described as an example, but any number of resin layers and inorganic insulating layers may be laminated. .

  Moreover, although embodiment mentioned above demonstrated the example in which the inorganic insulating part contains the 1st inorganic insulating particle and the 2nd inorganic insulating particle as an example, the inorganic insulating part may contain only either one, Both of them may not be included, and inorganic insulating particles having different particle diameters from the first inorganic insulating particles and the second inorganic insulating particles may be further included.

  Moreover, although embodiment of this invention mentioned above demonstrated to the example the structure in which a resin base | substrate contains a base material, the resin base | substrate does not need to contain a base material. When the wiring board includes a resin base that does not include a base material and an inorganic insulating layer, the inorganic insulating layer increases the rigidity of the wiring board while reducing the coefficient of thermal expansion in the plane direction, and does not include the base material. Thus, the flatness can be improved while reducing the thickness of the wiring board.

  Moreover, although embodiment mentioned above demonstrated the example in which the base | substrate was equipped with the resin base | substrate, you may use for a base | substrate what coat | covered the metal plate with resin.

  In the above-described embodiment of the present invention, the wiring board is described as an example in which both the core substrate and the wiring layer are provided with the inorganic insulating layer. However, the wiring board may include at least two inorganic insulating layers. The inorganic insulating layer may be provided only on either the core substrate or the wiring layer. When the wiring board has an inorganic insulating layer only in the wiring layer, the wiring board may include, for example, a ceramic substrate or the like as the core substrate, or may not include the core substrate.

  The above-described embodiment of the present invention is described by taking as an example a configuration in which the first inorganic insulating layer with which at least a part of one main surface of the first conductive layer abuts is an inorganic insulating layer formed on a resin substrate. However, the first inorganic insulating layer may be formed anywhere in the wiring substrate, or may be formed on the resin layer.

  Moreover, although embodiment mentioned above demonstrated the example in which the 1st conductive layer and the 2nd conductive layer were formed in the same layer as an example, you may form in a different layer.

  In the above-described embodiment of the present invention, the configuration in which the first conductive layer has the first convex portion on one main surface and the second convex portion on the other main surface has been described as an example. May be formed only.

  Moreover, although embodiment mentioned above demonstrated the structure which used copper foil in the process of (1) as an example, you may use metal foil other than copper foil, for example.

  Moreover, although embodiment of this invention mentioned above demonstrated the structure which heats inorganic insulation sol after evaporating a solvent in the process of (2) as an example, evaporation of a solvent and heating of inorganic insulation sol are carried out. You can go at the same time.

  Moreover, although embodiment of this invention mentioned above demonstrated to the example the structure which mounted the uncured 2nd resin contact bonding layer precursor on the lamination sheet at the process of (6), uncured and liquid 1st is demonstrated. Two resin adhesive layer precursors may be applied to the inorganic insulating layer.

  In the above-described embodiment of the present invention, the configuration in which the conductive layer is formed by the semi-additive method or the subtractive method in the step (8) has been described as an example. After removing the copper foil from the second resin adhesive layer by an etching method using a ferric chloride solution or a cupric chloride solution, the conductive layer is formed by a semi-additive method, a subtractive method, a full additive method, or the like. It may be formed.

DESCRIPTION OF SYMBOLS 1 Mounting structure 2 Electronic component 3 Wiring board 4 Bump 5 Core board 6 Wiring layer 7 Base body 8 Through-hole conductor
DESCRIPTION OF SYMBOLS 9 Insulator 10 Resin base | substrate 10x Resin base | substrate precursor 11 Inorganic insulating layer 11x Inorganic insulating sol 12 Resin layer 12a Extension part 12x Resin layer precursor 13 Conductive layer 13x Copper foil 14 Via conductor 15a 1st convex part 15b 2nd convex part 16 Laminated plate 17 Laminated sheet

Claims (7)

First and second inorganic insulating layers separated along the thickness direction, a first conductive layer partially formed between the first and second inorganic insulating layers, and the first and second inorganic insulating layers A resin layer disposed in parallel with the first conductive layer,
In the first conductive layer, at least a part of one main surface is in contact with the first inorganic insulating layer, and at least a part of the other main surface is in contact with the second inorganic insulating layer ,
The first conductive layer has a plurality of second protrusions that protrude toward the second inorganic insulating layer on the other main surface, and at least a part of which is in contact with the second inorganic insulating layer,
The resin layer partially extends between the first conductive layer and the second inorganic insulating layer, and the extended portion is filled between the second convex portions, and the first conductive layer and A wiring board, which is bonded to the second inorganic insulating layer . First and second inorganic insulating layers separated along the thickness direction, a first conductive layer partially formed between the first and second inorganic insulating layers, and the first and second inorganic insulating layers A resin layer disposed in parallel with the first conductive layer,
In the first conductive layer, at least a part of one main surface is in contact with the first inorganic insulating layer, and at least a part of the other main surface is in contact with the second inorganic insulating layer,
A second conductive layer that is a grounding wiring or a power supply wiring having a larger area in plan view than the first conductive layer;
The first conductive layer is a signal wiring, and the ratio of the contact area to the sum of the contact area and the non-contact area with the second inorganic insulating layer is larger than that of the second conductive layer. A characteristic wiring board. In the wiring board according to claim 1 or 2 ,
The wiring board, wherein the resin layer is bonded to the first and second inorganic insulating layers. In the wiring board according to claim 1 or 2 ,
A second conductive layer interposed between the first and second inorganic insulating layers and spaced apart from the first conductive layer along a planar direction;
The wiring board, wherein the resin layer is interposed between the first and second conductive layers. In the wiring board according to claim 1 or 2 ,
The first conductive layer has a plurality of first protrusions that protrude toward the first inorganic insulating layer on the one principal surface, and at least a part of the first conductive layer is in contact with the first inorganic insulating layer;
A part of said 1st inorganic insulating layer is filled between said 1st convex parts, The wiring board characterized by the above-mentioned. In the wiring board according to claim 1 or 2 ,
A third conductive layer spaced along the thickness direction with respect to the first conductive layer via the second inorganic insulating layer;
A via conductor penetrating through the second inorganic insulating layer in the thickness direction and electrically connected to the first and third conductive layers;
A wiring board further comprising: The wiring board according to claim 1 or 2 ,
An electronic component mounted on the wiring board and electrically connected to the first conductive layer;
A mounting structure characterized by comprising:

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