JP2013046012A - Wiring board and mounting structure therefor - Google Patents

Abstract

The present invention solves the above-described demand by providing a wiring board with improved electrical reliability and a mounting structure thereof.
A wiring board 3 according to an embodiment of the present invention includes a plurality of first inorganic insulating particles 14a containing silicon oxide connected to each other via a first neck structure 13a, and the first inorganic insulating particles 14a. And an insulating layer having a resin member 15 containing a resin having a siloxane bond as a skeleton, which is disposed between them. A mounting structure 1 according to an embodiment of the present invention includes the wiring board 3 and an electronic component 2 mounted on the wiring board 3.
[Selection] Figure 2

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) and a mounting structure thereof.

  Conventionally, a mounting structure in which an electronic component is mounted on a wiring board is used in an electronic device. As a wiring board used for this mounting structure, a substrate provided with a resin layer and a ceramic layer is known.

  For example, Patent Document 1 discloses a wiring board formed by spraying ceramic on one side of a metal foil to form a ceramic layer, laminating a prepreg so as to be in contact with the ceramic layer side of the metal foil, and hot pressing. Is described.

  However, in general, the ceramic layer has high rigidity but is easily cracked. Therefore, when stress is applied to the wiring board, cracks are likely to occur in the ceramic layer. Therefore, when the crack extends and reaches the wiring, the wiring is likely to be disconnected, and the electrical reliability of the wiring board is likely to be lowered.

  Therefore, it is desired to provide a wiring board with improved electrical reliability.

Japanese Patent Laid-Open No. 2-253941

  The present invention solves the above-described demand by providing a wiring board with improved electrical reliability and a mounting structure thereof.

  A wiring board according to an aspect of the present invention includes a plurality of first inorganic insulating particles containing silicon oxide connected to each other via a first neck structure, and siloxane disposed between the first inorganic insulating particles. And an insulating layer including a resin member including a resin whose bond is a skeleton.

  A mounting structure according to an aspect of the present invention includes the above wiring board and an electronic component mounted on the wiring board.

  According to the wiring board according to one aspect of the present invention, since the insulating layer in which the resin member is disposed between the first inorganic insulating particles connected to each other through the first neck structure is provided, the insulating substrate is insulated by the first inorganic insulating particles. Cracks can be reduced by the resin member while increasing the rigidity of the layer. Furthermore, since the first inorganic insulating particles include silicon oxide and the resin member includes a resin having a siloxane bond as a skeleton, the connection strength between the first inorganic insulating particles can be increased by the resin. As a result, cracks in the insulating layer can be reduced, and as a result, a wiring board having excellent electrical reliability can be obtained.

Fig.1 (a) is sectional drawing which cut | disconnected the mounting structure concerning one Embodiment of this invention in the thickness direction, FIG.1 (b) expanded and showed R1 part of Fig.1 (a). It is sectional drawing. 2 (a) is an enlarged cross-sectional view of the R3 portion of FIG. 1 (b), and FIG. 2 (b) schematically shows the connection of the two first inorganic insulating particles. Is. FIG. 3 is an enlarged cross-sectional view of a portion R2 in FIG. 4 (a) and 4 (b) are cross-sectional views illustrating the manufacturing process of the mounting structure shown in FIG. 1 (a), and FIG. 4 (c) is an enlarged view of the portion R4 in FIG. 4 (b). It is sectional drawing shown. 5 (a) and 5 (b) are enlarged sectional views illustrating a manufacturing process of the mounting structure shown in FIG. 1 (a) and showing a portion corresponding to the R4 portion in FIG. 4 (b). . 6 (a) and 6 (b) are enlarged sectional views illustrating a manufacturing process of the mounting structure shown in FIG. 1 (a) and showing a portion corresponding to the R4 portion in FIG. 4 (b). . FIGS. 7A to 7C are cross-sectional views illustrating a manufacturing process of the mounting structure shown in FIG. FIGS. 8A and 8B are cross-sectional views for explaining a manufacturing process of the mounting structure shown in FIG. FIGS. 9A and 9B are cross-sectional views for explaining a 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. 1A 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 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.

  The wiring substrate 3 includes a core substrate 5 and a pair of buildup layers 6 formed on the upper and lower surfaces of the core substrate 5. The wiring substrate 3 supports the electronic component 2 and drives or controls the electronic component 2. It has a function of supplying power and signals to the electronic component 2.

  Hereinafter, the configuration of the wiring board 3 will be described in detail.

(Core substrate)
The core substrate 5 is intended to increase the rigidity of the wiring substrate 3 while achieving conduction between the pair of buildup layers 6, a base 7 that supports the buildup layer 6, a through hole provided in the base 7, A cylindrical through-hole conductor 8 provided in the through-hole and electrically connecting the pair of buildup layers 6 to each other and an insulator 9 surrounded by the through-hole conductor 8 are included.

  The base 7 has a first resin layer 10a, a first insulating layer 11a provided on both main surfaces of the first resin layer 10a, and a main surface of the first insulating layer 11a opposite to the first resin layer 10a. And a second resin layer 10b provided.

The first resin layer 10a is a main part of the base 7, and includes, for example, a resin part and a base material covered with the resin part. The thickness of the 1st resin layer 10a is set, for example as 0.1 mm or more and 3.0 mm or less. The thermal expansion coefficient in the planar direction of the first resin layer 10a is set to, for example, 3 ppm / ° C. or more and 20 ppm / ° C. or less, and the thermal expansion coefficient in the thickness direction of the first resin layer 10a is, for example, 30 ppm / ° C. or more. It is set to 50 ppm / ° C. or less.

  Here, the thermal expansion coefficient of the first resin layer 10a is measured by a measurement method according to JISK7197-1991 using a commercially available TMA (Thermo-Mechanical Analysis) apparatus. In addition, the dielectric loss tangent of the first resin layer 10a is measured by a resonator method according to JIS R1627-1996. Hereinafter, the coefficient of thermal expansion of each member including the second, third, and fourth resin layers 10b, 10c, and 10d and the first and second insulating layers 11a and 11b is measured similarly to the first resin layer 10a. The

  The resin part of the first resin layer 10a can be formed of a thermosetting resin such as an epoxy resin, a bismaleimide triazine resin, a cyanate resin, a polyphenylene ether resin, a wholly aromatic polyamide resin, or a polyimide resin. By forming with such a thermosetting resin, the adhesive strength with the first insulating layer 11a can be increased, and the toughness of the first resin layer 10a is increased compared with the resin member 15 described later, and cracks are generated. Can be reduced. Especially, it is desirable to form the resin part of the 1st resin layer 10a with an epoxy resin from a viewpoint of the toughness of the 1st resin layer 10a, and the adhesive strength with the 1st insulating layer 11a.

  The resin portion of the first resin layer 10a has a Young's modulus set to, for example, 0.1 GPa to 5 GPa, and a coefficient of thermal expansion in the thickness direction and the plane direction set to, for example, 20 ppm / ° C. to 50 ppm / ° C. .

  Here, the Young's modulus of the resin portion of the first resin layer 10a is measured by a method according to ISO14577-1: 2002 using a nanoindenter XP manufactured by MTS. Hereinafter, the thermal expansion coefficient of each member including the second, third, and fourth resin layers 10b, 10c, and 10d and the first and second insulating layers 11a and 11b is the same as that of the resin portion of the first resin layer 10a. Is measured.

  The said base material contained in the 1st resin layer 10a increases the rigidity of the 1st resin layer 10a while reducing the thermal expansion coefficient of the planar direction of the 1st resin layer 10a. The base material can be formed of, for example, a woven or non-woven fabric composed of a plurality of fibers, or a group of fibers in which a plurality of fibers are arranged in one direction. As the fiber, for example, glass fiber, resin fiber, carbon fiber, metal fiber, or the like can be used.

  In the present embodiment, as shown in FIG. 1B, the first resin layer 10a further contains a first filler 12a made of a large number of first filler particles formed of an inorganic insulating material. As a result, the coefficient of thermal expansion of the first resin layer 10a can be reduced and the rigidity of the first resin layer 10a can be increased. The first filler particles can be formed of an inorganic insulating material such as silicon oxide, aluminum oxide, aluminum nitride, aluminum hydroxide, or calcium carbonate. The first filler particles have a particle size of, for example, 0.5 μm or more and 5.0 μm or less, and a coefficient of thermal expansion of, for example, 0 ppm / ° C. or more and 15 ppm / ° C. or less. Further, the ratio of the volume of the first filler 12a to the total volume of the resin portion of the first resin layer 10a and the first filler 12a (hereinafter referred to as “content of the first filler 12”) is, for example, 3% by volume to 60%. % Or less is set.

Here, the particle size of the first filler particles is measured as follows. First, a cross section of the first resin layer 10a is observed with a transmission electron microscope, and an enlarged cross section is photographed so as to include particles having a particle number of 20 or more and 50 or less. Next, the maximum diameter of each particle is measured in the enlarged cross section, and the measured maximum particle diameter is taken as the particle diameter of the first filler particles. Further, the content (volume%) of the first filler 12 is determined by taking a cross section of the first resin layer 10a with a transmission electron microscope and using an image analyzer or the like to occupy the resin portion of the first resin layer 10a. It is measured by measuring the area ratio (area%) of one filler 12a at 10 cross-sections, calculating the average value of the measured values, and regarding the content (volume%).

  On the other hand, the first insulating layers 11a formed on the upper and lower surfaces of the first resin layer 10a make the base body 7 highly rigid and have a low coefficient of thermal expansion. The thickness of the first insulating layer 11a is set to, for example, 3 μm to 100 μm and / or 3% to 10% of the first resin layer 10a. The Young's modulus of the first insulating layer 11a is set to, for example, 10 GPa or more and 50 GPa or less, and / or 10 times or more and 100 times or less of the resin portion of the first resin layer 10a. Further, the first insulating layer 11a has a coefficient of thermal expansion in the thickness direction and the plane direction set to, for example, 0 ppm / ° C. or more and 10 ppm / ° C. or less.

  As shown in FIGS. 1B to 2B, the first insulating layer 11a includes first inorganic insulating particles 14a and first inorganic insulating particles 14a connected to each other through a first neck structure 13a. And a resin member 15 disposed in the gap G. As a result, since the resin member 15 is arranged in the gap G between the first inorganic insulating particles 14a connected to each other via the first neck structure 13a, the first inorganic insulating particles 14a form a skeleton structure and the first insulating layer The crack of the 1st insulating layer 11a can be reduced because the resin member 15 eases the stress applied to the 1st inorganic insulating particle 14a, improving the rigidity of 11a.

  The 1st neck structure 13a is a structure which connects adjacent 1st inorganic insulating particles 14a, and a part area | region of the surface of each 1st inorganic insulating particle 14a, especially 1st inorganic insulating particles 14a adjoin. Formed in the region. The first inorganic insulating particles 14a connected to each other via the first neck structure 13a have a width that decreases toward the first neck structure 13a, and the first neck structure 13a has a constricted shape. Since the first inorganic insulating particles 14a are connected to each other through the first neck structure 13a, the open pore gap G can be satisfactorily formed in the first insulating layer 11a.

The first inorganic insulating particles 14a are formed of an inorganic insulating material containing silicon oxide (SiO ₂ ). As a result, the first inorganic insulating particles 14a can have a low coefficient of thermal expansion. As the first inorganic insulating particles 14a, for example, an inorganic insulating material containing 90% by weight or more of silicon oxide can be used. In particular, it is desirable to use an inorganic insulating material containing 99% by weight or more and less than 100% by weight of silicon oxide. . When an inorganic insulating material containing 90% by weight or more and less than 100% by weight of silicon oxide is used, the inorganic insulating material includes an inorganic insulating material such as aluminum oxide, titanium oxide, magnesium oxide or zirconium oxide in addition to silicon oxide. It doesn't matter.

  Furthermore, in the present embodiment, the first insulating layer 11a contains silicon oxide in an amorphous state. The amorphous silicon oxide can reduce the anisotropy of the coefficient of thermal expansion caused by the crystal structure as compared with the crystalline silicon oxide, so that the wiring substrate 3 is cooled after the wiring substrate 3 is heated. At this time, the shrinkage of the first insulating layer 11a can be made more uniform in the thickness direction and the planar direction, and the occurrence of cracks in the first insulating layer 11a can be reduced. Note that the inorganic insulating material containing amorphous silicon oxide has a crystal phase region set to, for example, less than 10% by volume, and more preferably set to less than 5% by volume.

Here, the volume ratio of the crystal phase region of the inorganic insulating material is measured as follows. First, a plurality of comparative samples including different ratios of 100% crystallized sample powder and amorphous powder are prepared, and the comparative sample is measured by an X-ray diffraction method. A calibration curve showing the relative relationship with the volume ratio is created. Next, the measurement sample is measured by the X-ray diffraction method, the measured value is compared with the calibration curve, and the volume ratio of the crystal phase region is calculated from the measured value. The volume ratio of the phase region is measured.

  The first inorganic insulating particles 14a are desirably set to have a particle size of 3 nm or more and 110 nm or less. As a result, the inside of the first insulating layer 11a can be densely formed, and the rigidity of the skeletal structure in which the first inorganic insulating particles 14a are connected via the first neck structure 13a can be increased.

  Furthermore, since the first inorganic insulating particles 14a have a very small particle size, the first inorganic insulating particles 14a are firmly bonded to each other at a temperature lower than the crystallization start temperature, so that the first inorganic insulating particles themselves are in an amorphous state. The particles can be connected as they are. In addition, when the particle diameter of the first inorganic insulating particles 14a is set to be as small as 3 nm or more and 110 nm or less, the atoms of the first inorganic insulating particles 14a, particularly the atoms on the surface, actively move, so that the temperature is lower than the crystallization start temperature. It is presumed that the first inorganic insulating particles 14a are firmly bonded even under such a low temperature. 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.

  The first inorganic insulating particles 14a are preferably spherical as in the present embodiment. As a result, since it becomes easy to fill the first inorganic insulating particles 14a, the internal structure of the first insulating layer 11a can be made dense.

  On the other hand, in the present embodiment, as shown in FIGS. 1B and 2A, the first insulating layer 11a has a particle size larger than that of the first inorganic insulating particles 14a. It further includes a plurality of second inorganic insulating particles 14b connected to each other. The second inorganic insulating particles 14b can be formed of the same inorganic insulating material as the first inorganic insulating particles 14a, and it is preferable that the second inorganic insulating particles 14b include silicon oxide in an amorphous state.

  Thus, since the 1st insulating layer 11a contains the 2nd inorganic insulating particle 14b with a larger particle size than the 1st inorganic insulating particle 14a, even if a crack arises, when a crack reaches the 2nd inorganic insulating particle 14b In addition, the extension of the cracks can be prevented by the second inorganic insulating particles 14b having a large particle diameter, or the cracks can be bypassed along the surface of the second inorganic insulating particles. As a result, cracks are prevented from penetrating the first or second insulating layer 11a, 11b and reaching the conductive layer 16, and disconnection of the conductive layer 16 starting from the crack can be reduced. In addition, as for such 2nd inorganic insulating particle 14b, it is desirable for the particle size to be set to 0.5 micrometer or more and 5 micrometers or less.

  Furthermore, it is desirable that the second inorganic insulating particles 14b have a higher hardness than the first inorganic insulating particles 14a. As a result, when the crack reaches the second inorganic insulating particle 14b, it is reduced that the crack extends into the second inorganic insulating particle 14b, and consequently the extension of the crack in the first insulating layer 11a is reduced. Can do. The hardness can be measured using a nanoindenter device.

  The second inorganic insulating particles 14b are connected to the adjacent first inorganic insulating particles 14a via the second neck structure 14b, and the second inorganic insulating particles 14b adjacent to each other via the first inorganic insulating particles 14a. Connected. As a result, the second inorganic insulating particles 14b can be firmly connected to each other by interposing the first inorganic insulating particles 14a having a small particle size and a high connection strength with other particles.

The second neck structure 13b includes adjacent first inorganic insulating particles 14a and second inorganic insulating particles 14b.
And is formed in a partial region on the surface of the first inorganic insulating particles 14a and the second inorganic insulating particles 14b. The first inorganic insulating particles 14a and the second inorganic insulating particles 14b connected via the second neck structure 13b are each reduced in width toward the second neck structure 13b, and the second neck structure 13b has a constricted shape. There is no. Since the first inorganic insulating particles 14a and the second inorganic insulating particles 14b are connected via the second neck structure 13b, the open pore gap G can be satisfactorily formed in the first insulating layer 11a. it can.

  The second inorganic insulating particles 14b have a width that decreases toward the second neck structure 13b, and the first inorganic insulating particles are connected at the connection points between the first inorganic insulating particles 14a and the second inorganic insulating particles 14b. Each of 14a and second inorganic insulating particles 14b is connected in a partial region of the surface to form second neck structure 13b. Since the first inorganic insulating particles 14a are connected to each other through the second neck structure 13b as described above, the open pore gap G can be satisfactorily formed in the first insulating layer 11.

  Here, the width of the first neck structure 13a is larger than the width of the second neck structure 13b. As a result, the skeletal structure in which the first inorganic insulating particles 14a are connected to each other can be further strengthened, and the rigidity of the first insulating layer 11a can be increased. The width of the first neck structure 13a is set to, for example, 3 nm or more and 25 nm or less, and the width of the second neck structure 13b is set to, for example, 3 nm or more and 15 nm or less.

  The second inorganic insulating particles 14b are more preferably spherical as in this embodiment. As a result, the surface of the second inorganic insulating particle 14b becomes smooth, the stress on the surface is dispersed, and the generation of cracks in the first insulating layer 11a starting from the surface of the second inorganic insulating particle 13b can be reduced. it can.

  Here, the first insulating layer 11a includes 20% by volume to 90% by volume of the first inorganic insulating particles 14a with respect to the total volume of the first inorganic insulating particles 14a and the second inorganic insulating particles 14b. On the other hand, the second inorganic insulating particles 14b are contained in an amount of 10% by volume to 80% by volume.

  The volume% of the first inorganic insulating particles 14a and the second inorganic insulating particles 14b is calculated as follows. First, a cross section of the first insulating layer 11a is taken with a transmission electron microscope. Next, the area ratio (area%) of the first inorganic insulating particles 14a and the second inorganic insulating particles 14b is measured from the photographed image using an image analyzer or the like. And the volume% of the 1st and 2nd inorganic insulating particles 14a and 14b is calculated by calculating the average value of this measured value. The first inorganic insulating particles 14a and the second inorganic insulating particles 14b have a particle size such that the cross section of the first insulating layer 11a is observed with a transmission electron microscope and includes 20 to 50 particles. It is measured by photographing an enlarged cross section and measuring the maximum diameter of each particle in the photographed enlarged cross section.

  On the other hand, the resin member 15 includes a resin (silicone resin) having a siloxane bond (—Si—O—Si—) as a skeleton (siloxane skeleton). As described above, by including a resin having a siloxane bond as a skeleton, the resin member 15 can firmly connect the first inorganic insulating particles 14a to each other as described later. Further, the silicone resin of the resin member 15 includes an epoxy group, an amino group, or an alkoxy group bonded to the siloxane skeleton. The resin member 15 includes a silicone resin curing catalyst in addition to the silicone resin, and the curing catalyst includes titanium or aluminum. The resin member 15 does not contain a filler from the viewpoint of filling into the gap G.

The resin member 15 has a Young's modulus set to, for example, 0.3 GPa or more and 2 GPa or less, and a coefficient of thermal expansion in a plane direction and a thickness direction is set to, for example, 20 ppm / ° C. or more and 50 ppm / ° C. or less. Moreover, the resin member 15 is set to 25 volume% or more and 38 volume% or less in the 1st insulating layer 11a, for example.

  The volume% of the resin member 15 in the first insulating layer 11a is calculated as follows. First, a cross section of the first insulating layer 11a is photographed with a transmission electron microscope. Next, the area ratio (area%) of the resin member 15 in the first insulating layer 11a is measured from the photographed image using an image analysis device or the like. And the volume% of the resin member 15 in the 1st insulating layer 11a is calculated by calculating the average value of this measured value.

  On the other hand, the second resin layer 10b provided on the first insulating layer 11a has a function of relaxing the thermal stress between the first insulating layer 11a and the conductive layer 16, and a conductivity caused by a crack in the first insulating layer 11a. This has a function of reducing the disconnection of the layer 16, and one main surface is in contact with the first insulating layer 11 a and the other main surface is in contact with the conductive layer 16. The second resin layer 10b includes, for example, a resin portion and a second filler 12b coated on the resin portion, and the second filler 12b is composed of a large number of second filler particles formed of an inorganic insulating material. .

  The second resin layer 10b has a thickness set to, for example, 0.1 μm to 5 μm, a Young's modulus set to, for example, 0.05 GPa to 5 GPa, and a thermal expansion coefficient in the thickness direction and the planar direction, for example, 20 ppm / It is set to not less than 100 ° C and not more than 100 ppm / ° C.

  As in the present embodiment, the second resin layer 10b is preferably set to have a smaller thickness and a lower Young's modulus than the first resin layer 10a and the first insulating layer 11a. In this case, the thermal stress resulting from the difference in thermal expansion between the first insulating layer 11a and the conductive layer 16 is alleviated by the second resin layer 10b that is thin and easily elastically deformed. Therefore, peeling of the conductive layer 16 from the first insulating layer 11a is suppressed, disconnection of the conductive layer 16 can be reduced, and as a result, the wiring substrate 3 having excellent electrical reliability can be obtained.

  The resin part of the second resin layer 10b is a main part of the second resin layer 10b, and is made of, for example, a resin material such as epoxy resin, bismaleimide triazine resin, cyanate resin or polyimide resin. Especially, it is desirable to use an epoxy resin from the viewpoint of the toughness of the second resin layer 10b and the adhesive strength with the first insulating layer 11a.

  The second filler 12b of the second resin layer 10b has a function of increasing the flame retardancy of the second resin layer 10b and a function of suppressing adhesion of laminated sheets to each other during handling, which will be described later, such as silicon oxide. It can be formed of an inorganic insulating material. The second filler particles of the second filler 12b have a particle size set to, for example, 0.05 μm or more and 0.7 μm or less, and the content in the second resin layer 10b is set to, for example, 0 volume% or more and 10 volume% or less. Has been.

  On the other hand, the 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 buildup layers 6 of the core substrate 5 is formed in a cylindrical shape along the inner wall of the through hole. The through-hole conductor 8 can be formed of, for example, a conductive material such as copper, silver, gold, aluminum, nickel, or chromium, and has a coefficient of thermal expansion of, for example, 14 ppm / ° C. or more and 18 ppm / ° C. or less.

  An insulator 9 is formed in a columnar shape in the hollow portion of the through-hole conductor 8 formed in a cylindrical shape. The insulator 9 can be formed of a resin material such as polyimide resin, acrylic resin, epoxy resin, cyanate resin, fluorine resin, polyphenylene ether resin, or bismaleimide triazine resin.

(Build-up layer)
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.

  Of the pair of buildup layers 6, one buildup layer 6 is connected to the electronic component 2 via bumps 3, and the other buildup layer 6 is connected to an external wiring board (not shown) via a bonding material (not shown). Connected.

  As shown in FIGS. 1A and 3, each build-up layer 6 includes a plurality of third resin layers 10c, a plurality of second insulating layers 11b, a plurality of fourth resin layers 10d, a plurality of conductive layers 16, and A plurality of via conductors 17 are included. The third resin layer 10c, the second insulating layer 11b, the fourth resin layer 10d, and the conductive layer 16 are sequentially laminated a plurality of times, and the conductive layer 16 is spaced apart on the fourth resin layer 10d in plan view. A plurality of third resin layers 10 c are bonded to the side surface and the upper surface of the conductive layer 16. The conductive layer 16 and the via conductor 17 are electrically connected to each other, and constitute a ground wiring, a power supply wiring, and / or a signal wiring.

  The third resin layer 10c adheres the second resin layer 10d or the fourth resin layer 10d and the second insulating layer 11b, and is disposed between the conductive layers 16 separated in plan view to prevent a short circuit. It is. The third resin layer 10c can be formed of a thermosetting resin such as an epoxy resin, a bismaleimide triazine resin, a cyanate resin, a polyphenylene ether resin, a wholly aromatic polyamide resin, or a polyimide resin. Especially, it is desirable to use an epoxy resin from the viewpoint of the toughness of the third resin layer 10c and the adhesive strength with the second insulating layer 11b.

  The third resin layer 10c has a thickness set to, for example, 3 μm to 30 μm, and a Young's modulus set to, for example, 0.2 GPa to 20 GPa. The third resin layer 10c has a coefficient of thermal expansion in the thickness direction and the planar direction set to, for example, 20 ppm / ° C. or more and 50 ppm / ° C. or less.

  Moreover, in this embodiment, as shown in FIG. 3, the 3rd resin layer 10c contains the 3rd filler 12c which consists of many 3rd filler particles formed with the inorganic insulating material. The third filler 12c can be formed of the same material as the first filler 12a, and can reduce the thermal expansion coefficient of the third resin layer 10c and increase the rigidity of the third resin layer 10c.

  The second insulating layer 11b is formed on the third resin layer 10c and has the same configuration as the first insulating layer 11a included in the base body 7 described above. As a result, the second insulating layer 11b has the same configuration as the first insulating layer 11a. There is an effect.

  The fourth resin layer 10d is formed on the second insulating layer 11b and has the same configuration as the second resin layer 10b included in the base 7 described above. As a result, the same as the second resin layer 10b. There is an effect.

  The plurality of conductive layers 16 are partially formed on the fourth resin layer 10d and are separated from each other in the thickness direction or the planar direction. The conductive layer 16 can be formed of a conductive material such as copper, silver, gold, aluminum, nickel, or chromium. The conductive layer 16 has a thickness set to 3 μm or more and 20 μm or less, and a thermal expansion coefficient set to, for example, 14 ppm / ° C. or more and 18 ppm / ° C. or less.

The via conductor 17 connects the conductive layers 16 spaced apart from each other in the thickness direction, and is formed in a columnar shape that becomes narrower toward the core substrate 5. The via conductor 17 can be formed of a conductive material such as copper, silver, gold, aluminum, nickel, or chromium, and has a coefficient of thermal expansion of, for example, 14 ppm / ° C. or more and 18 ppm / ° C. or less.

  Next, in the mounting structure 1 of this embodiment described above, the first insulating layer 11a will be described in detail.

(First insulation layer)
In the mounting structure 1 of the present embodiment, the first insulating layer 11a includes the first inorganic insulating particles 14a containing silicon oxide (SiO ₂ ) connected via the first neck structure 13a as described above, and the first insulating layer 11a. And a resin member 15 including a resin (silicone resin) having a siloxane bond (—Si—O—Si—) as a skeleton (siloxane skeleton), which is disposed between the inorganic insulating particles 13a. As a result, since the silicone resin is siloxane-bonded to both the first inorganic insulating particles 14a connected via the first neck structure 13a, the first inorganic insulating particles 14a can be firmly connected to each other.

  In particular, since the first inorganic insulating particles 14a are close to each other in the vicinity of the first neck structure 13a, the first inorganic insulating particles 14a are connected to each other through a siloxane skeleton of a silicone resin. Here, since the siloxane skeleton is similar to the molecular structure of silicon oxide, the characteristics are close to silicon oxide and the hardness is high. Therefore, since the first inorganic insulating particles 14a can be firmly connected to each other through the siloxane skeleton, it is possible to reduce the cracks in the first insulating layer 11a and obtain the wiring substrate 3 having excellent electrical reliability.

  Furthermore, similarly to the first inorganic insulating particles 14a, the resin member 15 can increase the connection strength between the first inorganic insulating particles 14a and the second inorganic insulating particles 14b.

  In the present embodiment, the silicone resin has an epoxy group, an amino group, or an alkoxy group bonded to the siloxane skeleton. As a result, the epoxy group, amino group, or alkoxy group crosslinks three-dimensionally, so that the toughness of the silicone resin can be increased. In particular, cracks in the first insulating layer 11a can be reduced by increasing the toughness of the silicone resin at locations where the distance between the first inorganic insulating particles 14a is large and the volume of the silicone resin is large.

  Here, the silicone resin preferably includes an epoxy group among an epoxy group, an amino group, and an alkoxy group. As a result, since the epoxy groups have a strong bonding force, the toughness of the silicone resin can be further increased. Furthermore, when an epoxy resin is used for the first resin layer 10a, the adhesive strength between the silicone resin and the epoxy resin can be increased by the epoxy group, so that the adhesive strength between the first insulating layer 11a and the first resin layer 10a is increased. Can be increased. The same applies to the adhesion between the first insulating layer 11a and the second resin layer 10b.

  Moreover, in this embodiment, the resin member 15 contains the curing catalyst which comprises titanium or aluminum. As a result, the polymerization degree of the siloxane bond of the silicone resin can be easily increased by the curing catalyst.

  Although the first insulating layer 11a has been described above, the second insulating layer 11b has the same configuration and effect as the first insulating layer 11a.

<Method for Manufacturing Mounting Structure 1>
Next, the manufacturing method of the mounting structure 1 mentioned above is demonstrated based on FIGS. The manufacturing method of the mounting structure 1 includes a manufacturing process of the core substrate 5, a build-up process of the build-up layer 6, and a mounting process of the electronic component 2.

(Manufacturing process of core substrate 5)
(1) An inorganic insulating sol 14x having a solid content including the first inorganic insulating particles 14a and the second inorganic insulating particles 14b and a solvent 18 in which the solid is dispersed is prepared.

  The inorganic insulating sol 14x includes, for example, a solid content of 10% to 50% by volume and a solvent of 50% to 90% by volume. Thereby, productivity of the insulating layer formed from the inorganic insulating sol 14x can be maintained high while keeping the viscosity of the inorganic insulating sol 14x low.

  The solid content of the inorganic insulating sol 14x includes, for example, 20% to 90% by volume of the first inorganic insulating particles 14a and 10% to 80% by volume of the second inorganic insulating particles 14b. Thereby, generation | occurrence | production of the crack in the 1st insulating layer 11a can be effectively reduced in the process of (3) mentioned later.

  The first inorganic insulating particles 14a can be produced, for example, by purifying a silicate compound such as a sodium silicate aqueous solution (water glass) and chemically depositing silicon oxide. In this case, since the first inorganic insulating particles 14a can be produced under low temperature conditions, the first inorganic insulating particles 14a in an amorphous state can be produced. In addition, the particle size of the first inorganic insulating particles 14a is adjusted by adjusting the deposition time of silicon oxide. Specifically, the particle size of the first inorganic insulating particles 14a increases as the deposition time increases. Therefore, in order to produce the first inorganic insulating particles 14a including the third inorganic insulating particles 14c and the fourth inorganic insulating particles 14d, two types of inorganic insulating particles formed with different silicon oxide deposition times are used. Can be mixed.

  On the other hand, when the second inorganic insulating particles 14b are made of silicon oxide, for example, a silicate compound such as an aqueous sodium silicate solution (water glass) is purified, and a solution in which silicon oxide is chemically deposited is sprayed into the flame. It can be produced by heating to 800 ° C. or higher and 1500 ° C. or lower while reducing the formation of aggregates. Therefore, since the second inorganic insulating particles 14b have a larger particle size than the first inorganic insulating particles 14a, it is easy to reduce the formation of aggregates during high-temperature heating, and can be easily manufactured by high-temperature heating. And as a result, the hardness can be easily increased.

  Moreover, it is desirable that the heating time for producing the second inorganic insulating particles 14b is 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 14b can be suppressed and the amorphous state can be maintained even when heated to 800 ° C. or higher and 1500 ° C. or lower.

  On the other hand, the solvent 18 contained in the inorganic insulating sol 14x is, for example, 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, An organic solvent containing dimethylacetamide and / or a mixture of two or more selected from these can be used.

  (2) Next, as shown in FIGS. 4A to 5A, a metal foil 16x formed of a conductive material such as copper and a second formed on one main surface of the metal foil 16x. A resin-coated metal foil provided with the resin layer 10b is prepared, and the inorganic insulating sol 11x is applied to one exposed main surface of the second resin layer 10c.

  The metal foil with resin can be formed by applying a resin varnish to the metal foil 16x using a bar coater, a die coater, a curtain coater, or the like and drying. The second resin layer 10b formed in this step is, for example, a B stage or a C stage.

  The inorganic insulating sol 14x can be applied using, for example, a dispenser, a bar coater, a die coater, or screen printing. At this time, as described above, since the solid content of the inorganic insulating sol 14x is set to 50% by volume or less, the viscosity of the inorganic insulating sol 14x is set low, and the flatness of the coated inorganic insulating sol 14x is increased. can do.

  Moreover, since the particle diameter of the first inorganic insulating particles 14a is set to 3 nm or more as described above, the viscosity of the inorganic insulating sol 14x is also reduced favorably by this, and the applied inorganic insulating sol 14x Flatness can be improved.

  (3) Subsequently, as shown in FIG. 5B, the inorganic insulating sol 14x is dried and the solvent 18 is evaporated.

  Here, although the inorganic insulating sol 14x contracts as the solvent 18 evaporates, the solvent 18 is contained in the gap G between the first and second inorganic insulating particles 14a and 14b, and the first and second inorganic insulating sols. The particles 14a and 14b themselves are not included. For this reason, if the inorganic insulating sol 14x includes the second inorganic insulating particles 14b having a large particle size, the area filled with the solvent 18 is reduced correspondingly, and the inorganic insulating sol 14x is inorganic when the solvent 18 evaporates. The shrinkage amount of the insulating sol 14x is reduced. That is, the contraction of the inorganic insulating sol 14x is regulated by the second inorganic insulating particles 14b. As a result, the generation of cracks due to the shrinkage of the inorganic insulating sol 14x can be reduced. Even if a crack occurs, the extension of the crack can be prevented by the second inorganic insulating particles 14b having a large particle diameter.

The inorganic insulating sol 14x is dried by, for example, heating and air drying. The drying temperature is set to, for example, 20 ° C. or higher and lower than the boiling point of the solvent 18 (in the case where two or more solvents are mixed), and the drying time is, for example, 20 seconds to 30 seconds. Set to minutes or less. As a result, the boiling of the solvent 18 is reduced, and the extrusion of the first and second inorganic insulating particles 14a and 14b is suppressed by the pressure of bubbles generated during the boiling, and the distribution of the particles can be made more uniform. It becomes possible.

  (4) As shown in FIG. 6 (a), the solid content of the remaining inorganic insulating sol 14x is heated to connect the first inorganic insulating particles 14a to each other via the first neck structure 13a. The particles 14a and the second inorganic insulating particles 14b are connected via the second neck structure 13b.

  Here, the inorganic insulating sol 14x of the present embodiment includes the first inorganic insulating particles 14a having a particle size set to 110 nm or less. As a result, the heating temperature of the inorganic insulating sol 14x is relatively low, for example, less than the crystallization start temperature of the first inorganic insulating particles 14a and the second inorganic insulating particles 14b, and further, the thermal decomposition start temperature of the second resin layer 10b. Even if it is less than low and low temperature, the 1st inorganic insulating particles 14a can be firmly connected.

  The temperature at which the first inorganic insulating particles 14a can be firmly connected is, for example, about 250 ° C. when the particle size of the first inorganic insulating particles 14a is set to 110 nm or less, and the particle size is 15 nm. When it is set below, it is about 150 ° C. The crystallization start temperature of silicon oxide contained in the first and second inorganic insulating particles 14a and 14b is about 1300 ° C. Moreover, when the 2nd resin layer 10b consists of an epoxy resin, the thermal decomposition start temperature is about 280 degreeC. This thermal decomposition start temperature is a temperature at which the mass of the resin is reduced by 5% in thermogravimetry according to ISO11358: 1997.

  The heating temperature of the inorganic insulating sol 14x is desirably set to be lower than the crystallization start temperature of the first inorganic insulating particles 14a and the second inorganic insulating particles 14b. As a result, the shrinkage of the crystallized particles due to the phase transition can be reduced, and the occurrence of cracks in the first insulating layer 11a can be reduced.

  Further, by heating at such a low temperature as described above, the first inorganic insulating particles 14a and the first inorganic insulating particles 14a and the second inorganic insulating particles 14a and the second inorganic insulating particles 14b are maintained while maintaining the particle shapes of the first inorganic insulating particles 14a and the second inorganic insulating particles 14b. The inorganic insulating particles 14b can be connected only in the proximity region. As a result, the first inorganic insulating particles 14a and the first inorganic insulating particles 14a and the second inorganic insulating particles 14b can be connected to each other while forming the first neck structure 13a and the second neck structure 13b. A gap G of open pores can be easily formed between the 1 inorganic insulating particles 14a.

  Furthermore, it is desirable that the heating temperature of the inorganic insulating sol 14x is set to be lower than the thermal decomposition start temperature of the second resin layer 10b. As a result, the characteristic deterioration of the second resin layer 10b can be suppressed. In addition, the heating temperature of the inorganic insulating sol 14x is desirably higher than the boiling point of the solvent 18 in order to evaporate the remaining solvent 18.

  In addition, as for the heating of the inorganic insulating sol 14x, it is desirable that the temperature is set to, for example, 100 degrees or more and less than 700 degrees, and the time is set to, for example, 0.5 hours or more and 24 hours or less.

  (5) As shown in FIG. 6B, by filling the gap G between the first inorganic insulating particles 14a with the liquid resin 15x, the liquid resin 15x is heated and polymerized to form the resin member 15. Then, the first insulating layer 11a is formed. As a result, the laminated sheet 19 including the metal foil 16x, the second resin layer 10b, and the first insulating layer 11a can be produced.

  Here, the liquid resin 15x contains silanol which is a monomer and does not contain a solvent. As a result, the liquid resin 15x contains silanol which is a monomer and has a low viscosity without mixing a solvent. Therefore, the liquid resin 15x is applied on the skeleton structure of the first inorganic insulating particles 14a. Thus, the liquid resin 15x is filled in the gap G by capillary action. Moreover, since it does not contain a solvent, it is possible to prevent generation of bubbles due to evaporation of the solvent.

  The liquid resin 15x may contain siloxane obtained by polymerizing silanol. In this case, the degree of polymerization of the siloxane is preferably low, for example, a dimer or a trimer. The liquid resin 15x may contain a solvent, but in this case, it is desirable that the amount of the solvent is very small.

  The liquid resin 15x further includes a curing catalyst comprising titanium or aluminum. As a result, the polymerization initiation temperature of silanol can be made lower than the boiling point of silanol by the curing catalyst. Therefore, by heating the liquid resin 15x at a temperature higher than the polymerization start temperature of silanol and lower than the boiling point, the silanol is polymerized with a siloxane bond to reduce the occurrence of voids by volatilization of the liquid resin before curing, thereby forming a siloxane skeleton. The resin member 15 can be formed.

  The heating temperature of the liquid resin 15x is set to, for example, 150 ° C. or more and 250 ° C. or less, and the heating time of the liquid resin 15x is set to, for example, 0.5 hours or more and 6 hours or less.

(6) As shown to Fig.7 (a), after preparing the 1st resin precursor sheet | seat 10ax and laminating | stacking the 1st insulating layer 11a of the lamination sheet 19 on the upper and lower surfaces of the 1st resin precursor sheet | seat 10ax, the said By heating and pressing the laminated body in the vertical direction, as shown in FIG. 7B, the first resin precursor sheet 10ax is cured to form the first resin layer 10a.

  The 1st resin precursor sheet | seat 10ax can be produced by laminating | stacking the some resin sheet containing uncured thermosetting resin and a base material, for example. The uncured state is an A-stage or B-stage according to ISO 472: 1999.

  The laminated sheet 19 is laminated such that the first insulating layer 11a is interposed between the metal foil 16x and the first resin precursor sheet 10ax.

  The heating temperature of the laminate is set to be equal to or higher than the curing start temperature of the first resin precursor sheet 10ax and lower than the thermal decomposition temperature. Specifically, when the first resin precursor sheet is made of an epoxy resin, a cyanate resin, a bismaleimide triazine resin or a polyphenylene ether resin, the heating temperature is set to 170 ° C. or higher and 230 ° C. or lower, for example. Moreover, the pressure of the said laminated body is set to 2 MPa or more and 3 MPa or less, for example, and the heating time and pressurization time are set to 0.5 hours or more and 2 hours or less, for example. The curing start temperature is a temperature at which the resin becomes a C-stage according to ISO 472: 1999.

  (7) As shown in FIG. 7C, a through-hole conductor 8 that penetrates the base body 7 in the thickness direction and an insulator 9 are formed inside the through-hole conductor 8, and then the through-hole conductor is formed on the base body 7. A conductive layer 16 connected to 8 is formed.

  The through-hole conductor 8 and the insulator 9 are formed as follows. First, a plurality of through holes penetrating the base body 7 and the metal foil 16x 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 insulator 9 is formed by filling the inside of the cylindrical through-hole conductor 8 with a resin material or the like.

  The conductive layer 16 is formed on the insulator 9 and the through-hole conductor 8 exposed from the through-hole formed in the metal foil 16x by, for example, an electroless plating method, a vapor deposition method, a CVD method, a sputtering method, or the like. A metal layer made of the same metal material is applied. Next, the conductive layer 16 is formed by patterning the metal foil 16x and / or the metal layer using a photolithography technique, etching, or the like. Alternatively, the conductive layer 16 may be formed by peeling the metal foil 16x once, forming a metal layer on the substrate 7, and patterning the metal layer.

  The core substrate 5 can be manufactured as described above.

(Build-up process of build-up layer 6)
(8) As shown in FIG. 8A, after the laminated sheet 19 is laminated on the upper and lower surfaces of the core substrate 5 via the third resin precursor sheet 10cx, the laminated body is heated and pressed in the vertical direction. Thus, as shown in FIG. 8B, the third resin precursor sheet 10cx is cured to form the third resin layer 10c.

  The laminated sheet 19 in this step includes the second insulating layer 11b, the fourth resin layer 10d, and the metal foil 16x, and can be produced, for example, in the same manner as the steps (1) to (5). The third resin precursor sheet 10cx is formed of the above-described uncured thermosetting resin that constitutes the third resin layer 10c.

  When forming the laminate, the second insulating layer 11b of the laminate sheet 19 is brought into contact with the third resin precursor sheet 10cx. Moreover, the heating and pressurization of the laminated body can be performed, for example, in the same manner as the step (6).

  (9) As shown in FIG. 9A, after the metal foil 16x is peeled off from the second insulating layer 11b, the via conductor 17 penetrating the third resin layer 10c and the second insulating layer 11b in the thickness direction is formed. At the same time, the conductive layer 16 is formed on the second insulating layer 11b.

  The metal foil 16x can be peeled by, for example, an etching method using a mixed solution of sulfuric acid and hydrogen peroxide solution, a ferric chloride solution, a cupric chloride solution, or the like.

  The via conductor 17 and the conductive layer 16 are specifically formed as follows. First, a via hole penetrating the third resin layer 10c and the second insulating layer 11b is formed by, for example, a YAG laser device or a carbon dioxide gas laser device. Next, the conductive layer 16 is formed by forming a via conductor 17 in the via hole and depositing a conductive material on the second insulating layer 11b by, for example, a semi-additive method, a subtractive method, or a full additive method. The conductive layer 16 may be formed by patterning the metal foil 16x without peeling off the metal foil 16x from the second insulating layer 11b.

  (10) As shown in FIG. 9B, the build-up layers 6 are formed above and below the core substrate 5 by repeating the steps (8) and (9). In addition, the build-up layer 6 can be multi-layered by repeating this process.

  The wiring board 3 can be produced as described above.

(Electronic component 2 mounting process)
(11) By mounting the electronic component 2 on the wiring board 3 via the bumps 4, the mounting structure 1 shown in FIG. 1A can be manufactured.

  The electronic component 2 may be electrically connected to the wiring board 3 by wire bonding, or may be incorporated in the wiring board 3.

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

  Further, in the above-described embodiment of the present invention, a buildup multilayer substrate composed of a core substrate and a buildup layer is cited as an example of the wiring substrate according to the present invention. However, an example of the wiring substrate according to the present invention is a build In addition to the up-multilayer substrate, for example, a single-layer substrate composed of an interposer substrate, a coreless substrate, or a core substrate, a ceramic substrate, a metal substrate, and a core substrate including a metal plate are also included.

  In the above-described embodiment of the present invention, the insulating layer includes the first inorganic insulating particles and the second inorganic insulating particles. However, the insulating layer only needs to include the first inorganic insulating particles. 2 The inorganic insulating particles may not be included, and the insulating layer may include inorganic insulating particles having a particle diameter different from that of the first inorganic insulating particles and the second inorganic insulating particles.

  Moreover, in the above-described embodiment of the present invention, the wiring board has the second resin layer and the fourth resin layer, but may not have the second resin layer and the fourth resin layer. In this case, the first insulating layer and the second insulating layer are in contact with the conductive layer. Such a 1st insulating layer and a 2nd insulating layer are formed by apply | coating an inorganic insulating sol directly on metal foil.

  In the above-described embodiment of the present invention, the first resin layer and the third resin layer are formed of a thermosetting resin. However, at least one of the first resin layer and the third resin layer or both of them are heated. It may be formed of a plastic resin. As this thermoplastic resin, for example, a fluorine resin, an aromatic liquid crystal polyester resin, a polyether ketone resin, a polyphenylene ether resin, or a polyimide resin can be used.

  In the embodiment of the present invention described above, both the core substrate and the buildup layer are provided with the insulating layer. However, the wiring board is provided with at least one of the core substrate and the buildup layer. It ’s fine.

  Moreover, in embodiment of this invention mentioned above, although evaporation of the solvent in a process (3) and solid content heating in a process (4) were performed separately, a process (3) and a process (4) were performed simultaneously. It doesn't matter.

  Moreover, in embodiment of this invention mentioned above, although the uncured 3rd resin precursor sheet | seat was mounted on the 2nd insulating layer at the process of (8), it is an uncured and 3rd resin precursor which is a liquid. May be applied to the second insulating layer.

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 Through-hole conductor 9 Insulator 10a 1st resin layer 10ax 1st resin precursor sheet 10b 2nd resin layer 10c 3rd resin layer 10cx third resin precursor sheet 10d fourth resin layer 11a first insulating layer 11b second insulating layer 11x inorganic insulating sol 12a first filler 12b second filler 13a first neck structure 13b second neck structure 14a first inorganic insulating particles 14b Second inorganic insulating particles 15 Resin member 16 Conductive layer 16x Metal foil 17 Via conductor 18 Solvent 19 Laminated sheet G Gap

Claims (6)

  A plurality of first inorganic insulating particles containing silicon oxide connected to each other via a first neck structure, and a resin member containing a resin having a siloxane bond as a skeleton, arranged between the first inorganic insulating particles; A wiring board comprising an insulating layer having The wiring board according to claim 1,
The wiring board, wherein the first inorganic insulating particles have a particle size of 3 nm to 110 nm. The wiring board according to claim 2,
The insulating layer further includes a plurality of second inorganic insulating particles containing silicon oxide and having a particle size of 0.5 μm or more and 5 μm or less and connected to each other via the first inorganic insulating particles,
The wiring board, wherein the second inorganic insulating particles are connected to the adjacent first inorganic insulating particles through a second neck structure. The wiring board according to claim 1,
The wiring board, wherein the resin having a siloxane bond as a skeleton includes an epoxy group, an amino group, or an alkoxy group. The wiring board according to claim 1,
The wiring board according to claim 1, wherein the resin member includes a curing catalyst comprising titanium or aluminum.   A mounting structure comprising the wiring board according to claim 1 and an electronic component mounted on the wiring board.

Images