JP5171750B2 - Bumped wiring board and mounting structure - Google Patents

Description

The present invention electronic device (e.g. various audio-visual equipment, home appliances, communications equipment, computer equipment and peripherals) relates bumped wiring base Ita及 beauty mounting structure used in the like.

  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 includes a wiring board having a conductive layer, an electronic component having an electrode, and a bump that is interposed between the wiring board and the electronic component and electrically connects the conductive layer and the electrode. A wiring board provided with the above is described.

  By the way, a thermal expansion coefficient differs between a wiring board and an electronic component. For this reason, when heat is generated from the electronic component during use of the mounting structure, thermal stress is generated between the wiring board and the electronic component. Such thermal stress tends to concentrate on the bumps interposed between the wiring board and the electronic component, and cracks occur in the connection part between the conductive layer of the wiring board and the bump and the connection part between the electrode of the electronic component and the bump. There is. As a result, a disconnection occurs in the electrical connection between the wiring board and the electronic component, and the electrical reliability of the mounting structure tends to decrease.

JP 2008-135518 A

The present invention is to provide a bumped wiring base Ita及 beauty mounting structure to meet the demand to improve the electrical reliability.

A wiring board with bumps according to one embodiment of the present invention includes a wiring board having an insulating layer and a conductive layer provided on the insulating layer, and provided on the conductive layer and electrically connected to the conductive layer. and bumps, and an inorganic insulating structure disposed continuously over the surface of the bump from the surface of the wiring substrate, the inorganic insulating structures that have a plurality of inorganic insulating particles coupled together.

A mounting structure according to an aspect of the present invention is an electronic component having the above-described wiring substrate with bumps and electrodes mounted on the wiring substrate and electrically connected to the conductive layer via the bumps on the surface. And comprising .

  According to the wiring board with bumps according to one embodiment of the present invention, the mechanical strength of the connection portion between the conductive layer and the bump can be improved. As a result, it is possible to obtain a bumped wiring board having excellent electrical reliability.

  According to the mounting structure according to one embodiment of the present invention, the mechanical strength of the connection portion between the conductive layer and the bump of the wiring board can be improved. As a result, a mounting structure with excellent electrical reliability can be obtained.

It is sectional drawing of the mounting structure concerning 1st Embodiment of this invention. In the mounting structure shown in FIG. 1, it is the top view which saw through the electronic component. It is sectional drawing of the wiring board with bump used for preparation of the mounting structure shown in FIG. 4a and 4b are cross-sectional views illustrating a manufacturing process of the mounting structure shown in FIG. 5a and 5b are cross-sectional views illustrating a manufacturing process of the mounting structure shown in FIG. 6a and 6b are cross-sectional views illustrating a manufacturing process of the mounting structure shown in FIG. It is sectional drawing of the mounting structure concerning 2nd Embodiment of this invention. In the mounting structure shown in FIG. 7, it is the bottom view which saw through the wiring board. It is sectional drawing of the electronic component with a bump used for preparation of the mounting structure shown in FIG. 10a and 10b are cross-sectional views illustrating a manufacturing process of the mounting structure shown in FIG. It is sectional drawing of the mounting structure concerning 3rd Embodiment of this invention. 12a and 12b are cross-sectional views illustrating a manufacturing process of the mounting structure shown in FIG. It is sectional drawing of the mounting structure concerning 4th Embodiment of this invention. 14a and 14b are cross-sectional views illustrating a manufacturing process of the mounting structure shown in FIG. 15a is a cross-sectional view of a mounting structure according to a fifth embodiment of the present invention, and FIG. 15b is a cross-sectional view of a mounting structure according to another embodiment of the present invention.

(First embodiment)
Hereinafter, a mounting structure according to a first embodiment of the present invention and a wiring board with bumps used for manufacturing the mounting structure will be described in detail with reference to FIGS.

(Mounting structure)
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, for example, and is flip-chip mounted on the wiring board 3 via bumps 4 and has a thickness set to 0.1 mm or more and 1 mm or less, for example. The electronic component 2 is electrically connected to a base material 2a on which elements and wirings are formed, an insulating coating 2b covering the elements and wirings on the surface of the base material 2a, and elements and wirings on the surface of the base material 2a. And an electrode 2c exposed from the coating 2b.

  The base material 2a functions as an integrated circuit, and can be made of a semiconductor material such as silicon, germanium, gallium arsenide, phosphorus gallium arsenide, gallium nitride, or silicon carbide, and has a thickness of, for example, 30 μm or more and 800 μm or less. Is set to

  The insulating coating 2b functions as an element on the surface of the base material 2a, a protective film for wiring, and an insulating member. For example, an insulating coating 2b formed of an inorganic insulating material such as silicon oxide or an organic insulating material such as polyimide can be used. Is set to 0.1 μm or more and 0.5 μm or less, for example. Here, it is desirable to use a low dielectric constant as the insulating coating 2b. As a result, the electric capacity between adjacent wires can be reduced, and the signal transmission speed in the wires can be increased. As such an insulating coating 2b having a low dielectric constant, one having a lower dielectric constant by making it porous can be used. The dielectric constant is in accordance with JISC2138: 2007.

  The electrode 2c functions as a connection member that electrically connects the wiring in the electronic component 2 to its external circuit, and can be formed of, for example, aluminum, copper, nickel, or gold, and has a thickness of, for example, It is set to 0.2 μm or more and 5 μm or less.

  The wiring substrate 3 includes a core substrate 5 and a pair of wiring layers 6 formed on both sides of the core substrate 5.

  The core substrate 5 is intended to increase the strength of the wiring substrate 3 while achieving conduction between the pair of wiring layers 6 and has a thickness of, for example, 0.3 mm to 1.5 mm. The core substrate 5 includes a base body 7, a through hole T, a through hole conductor 8, and an insulator 9.

  The substrate 7 is formed of, for example, a resin. Examples of the resin include an epoxy resin, a bismaleimide triazine resin, a cyanate resin, a polyparaphenylene benzbisoxazole resin, a wholly aromatic polyamide resin, a polyimide resin, an aromatic liquid crystal polyester resin, a poly Ether ether ketone resin or polyether ketone resin can be used.

  Further, the base body 7 may include a base material coated with a resin. 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 fiber, for example, glass fiber, resin fiber, carbon fiber or metal fiber can be used. The coefficient of thermal expansion of the substrate 7 is set to, for example, 1 ppm / ° C. or more and 16 ppm / ° C. or less. Such a coefficient of thermal expansion conforms to ISO11359-2: 1999.

  The base body 7 is provided with a plurality of cylindrical through holes T penetrating the base body 7 in the thickness direction (Z direction). Inside the through hole T, a through hole conductor 8 is formed in a cylindrical shape along the inner wall thereof. The through-hole conductor 8 is for electrically connecting the upper and lower wiring layers 6 of the core substrate 5, and for example, a through-hole conductor 8 made of a conductive material such as copper, silver, gold, aluminum, nickel, or chromium is used. Can do. An insulator 9 is formed in a columnar shape inside the cylindrical through-hole conductor 8. The insulator 9 forms a support surface of a via conductor 12 to be described later with its end face and the end face of the through-hole conductor 8. For example, polyimide resin, acrylic resin, epoxy resin, cyanate resin, fluororesin, silicon resin, What was formed with resin materials, such as a polyphenylene ether resin or a bismaleimide triazine resin, can be used.

  On the other hand, a pair of wiring layers 6 are formed on both sides of the core substrate 5 as described above. The wiring layer 6 is formed inside the plurality of insulating layers 10, the conductive layer 11 formed on the substrate 7 or on the insulating layer 10, the plurality of via holes V penetrating the insulating layer 10, and the via holes V. Via conductor 12. The conductive layer 11 and the via conductor 12 are electrically connected to each other and constitute a wiring part. The wiring portion includes a ground wiring, a power supply wiring, and / or a signal wiring.

  The insulating layer 10 is for ensuring insulation of portions other than the wiring portion in the wiring layer 6, and is formed to have a thickness of, for example, 1 μm or more and 15 μm or less. The insulating layer 10 is formed of, for example, polyimide resin, acrylic resin, epoxy resin, urethane resin, cyanate resin, silicon resin, bismaleimide triazine resin, liquid crystal polymer, polybenzoxazole resin, or polyimide benzoxazole resin. Can be used. The thermal expansion coefficient of the insulating layer 10 is set to, for example, 0 ppm / ° C. or more and 50 ppm / ° C. or less.

  Moreover, it is desirable that the insulating layer 10 contains a filler. As the filler material, a material having a thermal expansion coefficient of −5 ppm / ° C. or more and 5 ppm / ° C. or less, for example, silicon oxide, silicon carbide, aluminum oxide, aluminum nitride, or aluminum hydroxide can be used. The particle diameter of the filler is set to, for example, 0.5 μm or more and 15 μm or less.

  The conductive layer 11 is disposed on the base 7 and the insulating layer 10 with a gap. As the conductive layer 11, for example, a layer formed of a metal material such as copper, silver, gold, aluminum, nickel, or chromium can be used. The thickness of the conductive layer 11 is set to 3 μm or more and 20 μm or less. The thermal expansion coefficient of the conductive layer 11 is set to, for example, 14 ppm / ° C. or more and 18 ppm / ° C. or less.

  The via conductor 12 electrically connected to the conductive layer 11 connects the conductive layers 11 separated in the thickness direction of the insulating layer 10 to each other, and is formed so as to be narrower toward the core substrate 5. Has been. As the via conductor 12, for example, a conductor formed of a conductive material such as copper, silver, gold, aluminum, nickel, or chromium can be used.

  On the other hand, bumps 4 are interposed between the electronic component 2 and the wiring board 3. The bump 4 has a function of electrically connecting the electronic component 2 and the wiring substrate 3, and is electrically connected to the electrode 2 c on the lower surface of the electronic component 2 and the conductive layer 11 on the upper surface of the wiring substrate 3. . As this bump 4, what was formed with conductive materials, such as tin, lead, zinc, can be used, for example. Further, the bump 4 has a circular cross-sectional shape in the plane direction (XY plane direction), and has a wide portion having a cross-sectional area larger than that of the upper surface and the lower surface, and between the conductive layer 11 of the wiring board 3 and the bump 4. The corner part formed in the step 4 forms a hollow part that is recessed toward the inside of the bump 4.

  In the mounting structure 1 of the first embodiment, the inorganic insulating structure 13 is continuously formed from the surface of the wiring board 3 to the surface of the bump 4. The inorganic insulating structure 13 has, for example, a plurality of inorganic insulating particles bonded to each other, the inside is densely formed, and the mechanical strength is high. As the inorganic insulating structure 13, for example, one formed of a ceramic material such as silicon oxide, aluminum oxide, boron oxide, magnesium oxide, or calcium oxide can be used.

  An underfill 14 is filled between the electronic component 2 and the wiring board 3. The underfill 14 is bonded to the electronic component 2, the wiring substrate 3, the bump 4, and the inorganic insulating structure 13, and has a function of improving connection reliability in the bump 4 interposed between the electronic component 2 and the wiring substrate 3. Have As the underfill 14, one formed of a resin material such as an epoxy resin or a cyanate resin can be used. The underfill 14 has a coefficient of thermal expansion set to 0 ppm / ° C. or more and 100 ppm / ° C. or less, for example.

  By the way, since the electronic component 2 and the wiring board 3 have different coefficients of thermal expansion, thermal stress is generated between the electronic component 2 and the wiring board 3 due to heat generated from the electronic component 2 when the mounting structure 1 is used. Occur. Such thermal stress is likely to be concentrated on the bumps 4 interposed between the electronic component 2 and the wiring board 3, and in particular, the connection portion between the conductive layer 11 of the wiring board 3 and the bumps 4 and the electrode 2 c of the electronic component 2. It is easy to concentrate on the connection part between the bump 4 and the bump 4.

  On the other hand, as described above, the wiring board 3 is formed with the inorganic insulating structure 13 having high mechanical strength continuously from the surface of the wiring board 3 to the surface of the bumps 4, so that the thermal stress is easily concentrated. 3 can increase the mechanical strength at the connection portion between the conductive layer 11 and the bump 4. As a result, by reducing the occurrence of cracks in the connection portion, the connection reliability between the conductive layer 11 and the bump 4 of the wiring board 3 can be improved, and the electrical reliability of the mounting structure 1 can be improved. .

  In addition, the elastic modulus of the inorganic insulating structure 13 is set to, for example, 50 GPa or more and 300 GPa or less, and in particular, it is desirable to set it to 60 GPa or more. As the inorganic insulating structure 13 having such an elastic modulus, a ceramic material such as silicon oxide, aluminum oxide, boron oxide, magnesium oxide or calcium oxide, and a compound thereof can be used. The elastic modulus conforms to JIS R1602: 1995.

  In addition, since the inorganic insulating structure 13 is made of an inorganic insulating material, it can be made of a material having a low coefficient of thermal expansion compared to the wiring substrate 3 mainly made of an organic material. By using a material having a rate of thermal stress, it is possible to relieve thermal stress caused by the difference in thermal expansion coefficient between the electronic component 2 and the wiring board 3. In addition, the thermal expansion coefficient of the inorganic insulating structure 13 is set to, for example, 1 ppm / ° C. or more and 13 ppm / ° C. or less, and in particular, is desirably set to 3 ppm / ° C. or more and 5 ppm / ° C. or less. As the inorganic insulating structure 13 having such a thermal expansion coefficient, those formed from ceramic materials such as silicon oxide, aluminum oxide, boron oxide, magnesium oxide or calcium oxide, and compounds thereof can be used.

  Further, since the inorganic insulating structure 13 is made of an inorganic insulating material, it can be made of a material having a low dielectric loss tangent compared to the wiring substrate 3 mainly made of an organic material. By using a tangent material, it is possible to improve the high-frequency signal transmission characteristics in the bumps 4. In addition, the dielectric loss tangent of the inorganic insulating structure 13 is set to, for example, 0.002 or more and 0.01 or less, and in particular, it is desirable to set it to 0.002 or more and 0.005 or less. As such a dielectric loss tangent inorganic insulating structure 13, one formed from a ceramic material such as silicon oxide, aluminum oxide, boron oxide, magnesium oxide or calcium oxide can be used. In addition, a dielectric loss tangent is based on JISC2138: 2007.

  Further, it is desirable that the inorganic insulating structure 13 is in continuous contact from the surface of the wiring board 3 to the surface of the bump 4, and in particular, formed between the conductive layer 11 of the wiring board 3 and the bump 4. It is desirable that the corners to be in contact with the surface of the conductive layer 11 of the wiring board 3 and the surface of the bump 4. As a result, the mechanical strength of the corner where thermal stress is most likely to concentrate can be increased, and the connection reliability between the conductive layer 11 and the bump 4 of the wiring board 3 can be increased.

  Further, as in the present embodiment, the bump 4 has a wide portion, and a corner portion formed between the conductive layer 11 of the wiring substrate 3 and the bump 4 is recessed toward the inside of the bump 4. It is desirable that the inorganic insulating structure 13 is disposed in the recess. As a result, it is possible to increase the mechanical strength of the recessed portion where thermal stress tends to concentrate, and to improve the connection reliability between the conductive layer 11 and the bump 4 of the wiring board 3. When the inorganic insulating structure 13 is formed of a material having a lower thermal expansion than that of the wiring substrate 3, the difference in thermal expansion between the electronic component 2 and the wiring substrate 3 is further reduced in the recess. It is possible to reduce the thermal stress applied to the recess. Further, from the viewpoint of reducing thermal stress, it is desirable that the recess is filled with the inorganic insulating structure 13 and is in contact with the surface of the conductive layer 11 of the wiring board 3 and the surface of the bump 4 in the recess.

  The inorganic insulating structure 13 is preferably provided continuously from the surface of the wiring substrate 3 to the surface of the upper portion of the wide portion of the bump 4. As a result, the mechanical strength at the connection portion between the conductive layer 11 of the wiring board 3 and the bump 4 can be efficiently increased, and the connection reliability between the conductive layer 11 of the wiring board 3 and the bump 4 can be improved.

  In addition, it is desirable that the inorganic insulating structure 13 is continuously provided on the side surface of the bump 4 from the lower end to the upper end of the bump 4. As a result, the mechanical strength at the connection portion between the conductive layer 11 of the wiring board 3 and the bump 4 can be efficiently increased, and the connection reliability between the conductive layer 11 of the wiring board 3 and the bump 4 can be improved.

  The inorganic insulating structure 13 is preferably provided along the circumferential direction of the bump 4. As a result, the inorganic insulating structure 13 can support the connection portion between the wiring substrate 3 and the bump 4 over the entire periphery thereof, and can reduce the concentration of thermal stress at one location around the connection portion. Therefore, the connection reliability between the conductive layer 11 and the bump 4 of the wiring board 3 can be improved.

  In addition, it is desirable that the inorganic insulating structure 13 has a concave curved surface between the surface of the wiring substrate 3 and the surface of the bump 4, and the underfill 14 is in contact with the concave curved surface. As a result, the adhesive strength between the inorganic insulating structure 13 and the underfill 14 can be increased.

  In addition, the inorganic insulating structure 13 preferably has a concave portion on the surface thereof, and the underfill 14 is filled in the concave portion. As a result, the adhesive strength between the inorganic insulating structure 13 and the underfill 14 can be increased.

  Moreover, it is desirable that the upper surface of the conductive layer 11 on which the bumps 4 are formed is composed of only the region where the bumps 4 are formed and the region covered with the inorganic insulating structure 13. That is, the upper surface of the conductive layer 11 is preferably covered with the inorganic insulating structure 13 in a region other than the connection region with the bump 4. As a result, the surface of the conductive layer 11 can be protected by the inorganic insulating structure 13 without forming a solder resist layer containing a resin, and the mechanical strength of the connection portion between the conductive layer 11 and the bump 4 can be increased. Can do. From the viewpoint of surface protection, when the conductive layer 11 on which the bumps 4 are not formed is disposed on the upper surface of the wiring substrate 3, it is desirable that the upper surface of the conductive layer 11 is covered with the inorganic insulating structure 13. .

  In addition, in the bump 4, when the adjacent bumps 4 are the first bump 4 and the second bump 4, the inorganic insulating structure 13 is connected to the second bump through the surface of the wiring substrate 3 from the surface of the first bump 4. It is desirable to be provided continuously over the surface of 4. As a result, the surface of the insulating layer 10 can be protected by the inorganic insulating structure 13 without forming a solder resist layer containing a resin. In addition, since the inorganic insulating structure 13 can be made of a material having a low thermal expansion as compared with a solder resist layer made of an organic material, the difference in thermal expansion between the electronic component 2 and the wiring board 3 is alleviated. The thermal stress generated between 2 and the wiring board 3 can be reduced.

  As shown in FIG. 2, the inorganic insulating structure 13 desirably covers the entire upper surface of the wiring substrate 3. As a result, the surface of the wiring board 3 can be protected by the inorganic insulating structure 13 without forming a solder resist layer containing resin. In this case, on the upper surface of the inorganic insulating structure 13, it is desirable that the portion corresponding to the conductive layer 11 on the upper surface of the wiring substrate 3 is raised than the portion corresponding to the insulating layer 10 on the upper surface of the wiring substrate 3. As a result, the difference in the thickness of the inorganic insulating structure 13 at the site corresponding to the conductive layer 11 and the site corresponding to the insulating layer 10 can be reduced, and the effect of protecting the surface of the conductive layer 11 can be enhanced.

  Further, the inorganic insulating particles constituting the inorganic insulating structure 13 are preferably spherical. As a result, the mechanical strength of the inorganic insulating structure 13 can be improved by densifying the internal structure of the inorganic insulating structure 13.

  The particle diameter of the inorganic insulating particles is preferably set to 3 nm or more and 50 nm or less. As a result, the internal structure of the inorganic insulating structure 13 can be made dense.

  The inorganic insulating particles are desirably bonded to the filler contained in the insulating layer 10. As a result, the adhesive strength between the inorganic insulating structure 13 and the insulating layer 10 can be improved.

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

(Wiring board with bumps)
The bumped wiring board 15 shown in FIG. 3 is used for manufacturing the mounting structure 1 described above. The wiring board 15 with bumps includes a wiring board 3, a bump 4 provided on the conductive layer 11 of the wiring board 3, and an inorganic insulating structure provided continuously from the surface of the wiring board 3 to the surface of the bump 4. 13.

  The wiring board 3 has the same configuration as the wiring board 3 included in the mounting structure 1 described above.

  The bump 4 has the same configuration as the bump 4 included in the mounting structure 1 described above except that the bump 4 is not connected to the electronic component 2. The upper surface of the bump 4 has an exposed curved surface and is connected to the electronic component 2.

  As described above, the inorganic insulating structure 13 is continuously provided from the surface of the wiring substrate 3 to the surface of the bump 4. As a result, by mounting the electronic component 2 on the wiring board 15 with bumps, the above-described mounting structure 1 having excellent electrical reliability can be manufactured. Further, by increasing the mechanical strength at the connection portion between the conductive layer 11 and the bump 4 of the wiring board 3 where stress is easily concentrated, the mechanical stress during transportation of the wiring board 15 with bumps and the thermal stress during mounting of the electronic component 2 are increased. Since it is possible to reduce the occurrence of cracks in the connection portion due to the above, it is possible to manufacture the mounting structure 1 having excellent electrical reliability with a high yield.

  Here, the inorganic insulating structure 13 is preferably formed on the side surface of the bump 4. As a result, since the upper surface of the bump 4 can be exposed, the bump 4 and the electrode 2c of the electronic component 2 can be easily connected, and the electrical connection reliability between the bump 4 and the electrode 2c of the electronic component 2 can be easily established. Can be improved.

  Next, a method for manufacturing the mounting structure 1 using the above-described bumped wiring board 15 will be described with reference to FIGS.

(Production of bumped wiring board)
(1) As shown in FIG. 4a, a core substrate 5 is prepared. Specifically, this is performed as follows.

  First, the base body 7 is prepared. The base body 7 can be produced, for example, by laminating a plurality of resin sheets including an uncured resin and a base material and curing the uncured resin by heating and pressing. The uncured state is an A-stage or B-stage according to ISO 472: 1999.

  Next, a plurality of through holes T penetrating the base body 7 in the thickness direction are formed. The through hole T can be formed by, for example, drilling or laser processing.

  Next, a conductive material is deposited on the inner wall of the through hole T to form a cylindrical through hole conductor 8. Further, a conductive material layer is formed by depositing a conductive material on the upper surface and the lower surface of the substrate 7. The conductive material is deposited by, for example, electroless plating, vapor deposition, CVD, or sputtering.

  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, after the conductive material is deposited on the exposed portion of the insulator 9, the conductive layer 11 is formed by patterning the conductive layer material layer. The conductive material is deposited by, for example, an electroless plating method, a vapor deposition method, a CVD method, or a sputtering method. The patterning of the conductive material layer is performed using, for example, a conventionally known photolithography technique, etching, or the like.

  The core substrate 5 can be manufactured as described above.

  (2) As shown in FIG. 4 b, the wiring layer 6 is formed on both surfaces of the core substrate 5 to produce the wiring substrate 3. Specifically, the wiring layer 6 is performed as follows.

  First, the insulating layer 10 is formed over the conductive layer 11. The insulating layer 10 is formed, for example, by placing an uncured resin on the conductive layer 11 and heating the resin so that the resin is fluidly adhered and further heating to cure the resin.

  Next, a via hole V is formed in the insulating layer 10, and at least a part of the conductive layer 11 is exposed in the via hole V. For example, a YAG laser device or a carbon dioxide gas laser device is used to form the via hole V. The via hole V can be formed so that the opening width becomes narrower toward the core substrate 5 by adjusting the output of the laser beam.

  Next, the via conductor 12 is formed in the via hole V, and the conductive layer 11 is formed on the upper surface of the insulating layer 10. The via conductor 12 and the conductive layer 11 are formed by a conventionally known semi-additive method, subtractive method, full-additive method, or the like, and it is preferable that the via conductor 12 and the conductive layer 11 are formed by the semi-additive method.

  The wiring board 3 can be produced as described above. By repeating this process, a multilayer wiring substrate 3 can also be produced.

  (3) As shown in FIGS. 4 c and 5 a, bumps 4 are formed on the conductive layer 11. Specifically, it is performed as follows.

  First, as shown in FIG. 4 c, columnar bumps 4 are formed on the conductive layer 11. The bump 4 is formed by, for example, a printing method, a plating method, a vapor deposition method, or the like. Next, as shown in FIG. 5 a, the bump 4 having the shape included in the wiring board 15 with bumps described above can be formed by heating and melting the bumps 4. Moreover, the adhesive strength between the bump 4 and the conductive layer 11 can be increased by heating and melting. Further, when the bump 4 includes impurities such as flux, the impurities can be removed by vaporization. The heating temperature is preferably set to be equal to or higher than the melting point of the conductive material included in the bump 4 and lower than the thermal decomposition temperature of the resin material included in the wiring board 3.

  As described above, the bumps 4 can be formed on the conductive layer 11.

  (4) As shown in FIG. 5 b, the inorganic insulating structure 13 is formed on the wiring board 3 to produce the bumped wiring board 15. Specifically, it is performed as follows.

  First, an inorganic insulating sol containing inorganic insulating particles and a solvent is prepared. Next, an inorganic insulating sol is applied on the insulating layer 10. Next, the inorganic insulating sol is dried and the solvent is evaporated. As a result, inorganic insulating particles remain on the surface of the insulating layer 10 and the surface of the bump 4, and the inorganic insulating structure 13 having inorganic insulating particles is continuously formed from the surface of the wiring substrate 3 to the surface of the bump 4. Can do.

  The inorganic insulating sol preferably contains 1% to 50% of inorganic insulating particles and 50% to 98% of a solvent. As a result, by including 1% or more of inorganic insulating particles, the internal structure of the inorganic insulating structure 13 can be made dense and thick. Further, by containing 50% or more of the solvent, the fluidity of the inorganic insulating sol can be improved and the inorganic insulating particles can be efficiently filled.

  The inorganic insulating particles are preferably spherical. As a result, since the inorganic insulating particles can be densely aggregated when the solvent is evaporated, the inorganic insulating particles can be efficiently left on the upper surface of the insulating layer 10.

  The particle diameter of the inorganic insulating particles is preferably set to 3 nm or more and 50 nm or less. By setting the particle diameter of the inorganic insulating particles to 3 nm or more, the viscosity of the inorganic insulating sol can be reduced and the productivity can be improved. Further, by setting the particle diameter of the inorganic insulating particles to 50 nm or less, the inorganic insulating particles can be bonded to each other at a temperature lower than the thermal decomposition temperature of the resin contained in the insulating layer 10 as described later.

  As the solvent, for example, a solvent containing an organic solvent such as methanol, isopropanol, methyl ethyl ketone, methyl isobutyl ketone, propylene glycol monomethyl ether or dimethylacetamide can be used. Among these, it is desirable to use one containing methanol or propylene glycol monomethyl ether. As a result, the inorganic insulating sol can be uniformly applied and the solvent can be efficiently evaporated.

  The inorganic insulating sol can be applied using, for example, a dispenser or screen printing. Here, it is desirable that the inorganic insulating sol be applied to a portion other than the upper surface of the bump 4. As a result, the upper surface of the bump 4 can be exposed, and the bump 4 and the electrode 2c of the electronic component 2 can be easily connected. In addition, application | coating to a predetermined place can be performed by adjusting a coating amount, when using a dispenser, and using a mask when using screen printing. When the inorganic insulating sol is applied to the upper surface of the bump 4, the upper surface of the bump 4 can be exposed by wiping the inorganic insulating sol on the upper surface of the bump 4 with a nonwoven fabric or the like.

  The inorganic insulating sol can be dried, for example, in an inert gas such as nitrogen gas. Here, it is desirable to heat the inorganic insulating structure 13 during or after drying the inorganic insulating sol. As a result, the inorganic insulating particles can be bonded to each other. Here, when the particle diameter of the inorganic insulating particles is set to 50 nm or less, the inorganic insulating particles 13 are bonded to each other by heating the inorganic insulating structure 13 below the thermal decomposition temperature of the resin contained in the insulating layer 10. be able to. This is because the inorganic insulating particles are set to a very small particle size of 50 nm or less, and the atoms of the inorganic insulating particles, particularly the atoms on the surface, actively move, so that the inorganic insulating particles are bonded to each other even at such a low temperature. It is presumed to be caused by this. By bonding the inorganic insulating particles in this manner, the mechanical strength of the inorganic insulating structure 13 can be improved while reducing damage to the resin contained in the insulating layer 10 due to heating.

  In addition, since the inorganic insulating particles can be bonded to each other at a low temperature, crystallization of the inorganic insulating particles can be reduced and the ratio of the amorphous state can be increased. As a result, the inorganic insulating particles can reduce the occurrence of cracks by reducing the anisotropy of the thermal expansion coefficient due to the crystal structure anisotropy. In particular, when silicon oxide is used as the inorganic insulating particles, crystallization of the inorganic insulating particles can be effectively reduced. In addition, since such heating is performed at a low temperature, the stress generated during heating due to the difference in thermal expansion between the inorganic insulating particles and the insulating layer 10 is reduced, and cracks and peeling due to the stress can be prevented.

  As described above, the bumped wiring board 15 can be formed.

(Production of mounting structure)
(5) As shown in FIGS. 6a and 6b, the electronic component 2 is mounted on the wiring board 15 with bumps.

  First, as shown in FIG. 6a, the electronic component 2 is mounted on the wiring board 15 with bumps, and the bumps 4 and the electrodes 2c of the electronic component 2 are brought into contact with each other. Next, as shown in FIG. 6 b, the bump 4 and the electrode 2 c of the electronic component 2 are bonded by heating and melting the bump 4. The heating temperature is the same as the heating temperature in (4) described above, for example. As a result, the electronic component 2 can be mounted on the wiring board 3, and the bump 4 and the electrode 2c of the electronic component 2 can be electrically connected.

  By the way, during the heat melting, the electronic component 2 and the wiring board 3 have different coefficients of thermal expansion, so that thermal stress is generated between the electronic component 2 and the wiring board 3. Such thermal stress is likely to be concentrated on the bumps 4 interposed between the electronic component 2 and the wiring substrate 3, and in particular, the connection portion between the conductive layer 11 of the wiring substrate 3 and the bump 4 and the electrode 2 c of the electronic component 2. It is easy to concentrate on the connection part with the bump 4.

  On the other hand, in the wiring substrate 15 with bumps, as described above, since the inorganic insulating structure 13 is continuously formed from the surface of the wiring substrate 3 to the surface of the bumps 4, the conductivity of the wiring substrate 3 where thermal stress is likely to concentrate. The mechanical strength at the connection portion between the layer 11 and the bump 4 can be increased. As a result, by reducing the occurrence of cracks in the connection portion, the connection reliability between the conductive layer 11 and the bump 4 of the wiring board 3 is improved, and the mounting structure 1 having excellent electrical reliability is improved with a high yield. Can be made.

  Further, when the bump 4 is heated and melted, the shape of the bump 4 can be maintained by the inorganic insulating structure 13, so that the bump 4 can be formed higher in the vertical direction than the width in the plane direction. As a result, the distance between the electronic component 2 and the wiring board 3 can be increased while miniaturizing the wiring, and the thermal stress generated between the electronic component 2 and the wiring board 3 can be reduced.

  As described above, the electronic component 2 can be mounted on the bumped wiring board 15.

  (6) An underfill 14 is formed between the electronic component 2 and the wiring board 3 to produce the mounting structure 1 shown in FIG. Specifically, it is performed as follows.

  First, an A-stage liquid resin to be the underfill 14 is prepared, and the liquid resin is filled between the electronic component 2 and the wiring board 3. Next, the underfill 14 can be formed between the electronic component 2 and the wiring board 3 by heating and curing the liquid resin. The heating temperature is preferably set to be equal to or higher than the curing start temperature of the underfill 14 and lower than the thermal decomposition temperature.

  Here, when the solder resist layer is not formed on the wiring board 3, the gap between the electronic component 2 and the wiring board 3 can be increased, so that liquid resin is efficiently used between the electronic component 2 and the wiring board 3. Can be filled well.

  As described above, the mounting structure 1 can be manufactured.

(Second Embodiment)
Next, a mounting structure according to a second embodiment of the present invention and an electronic component with bumps used for manufacturing the mounting structure will be described in detail with reference to FIGS. In addition, description is abbreviate | omitted regarding the structure similar to 1st Embodiment mentioned above.

(Mounting structure)
As shown in FIG. 7, the second embodiment differs from the first embodiment in that the inorganic insulating structure 13A is continuously formed from the surface of the electronic component 2A to the surface of the bump 4A. In comparison, the mechanical strength can be increased at the connection portion between the electrode 2cA and the bump 4A of the electronic component 2A, in which thermal stress tends to concentrate and is fine. As a result, the occurrence of cracks in the connection portion can be reduced, so that the connection reliability between the conductive layer 11A of the wiring board 3A and the bump 4A is improved, and the electrical reliability of the mounting structure 1A is improved. Can do.

  By the way, for example, when a porous material is used for the insulating coating b2A for the purpose of reducing the dielectric constant in the insulating coating 2bA of the electronic component 2A, the mechanical strength of the insulating coating 2A is likely to be lowered. In this case, the thermal stress concentrated on the connection portion between the electrode 2cA of the electronic component 2A and the bump 4A is also applied to the electrode 2cA formation region of the insulating coating 2bA, thereby generating a crack in the insulating coating 2bA. It may extend to the base material 2aA and the reliability of the electronic component 2A may be reduced.

  On the other hand, as described above, since the inorganic insulating structure 13A is continuously formed from the surface of the wiring substrate 3A to the surface of the bump 4A in the wiring substrate 3A, the connection between the conductive layer 11A of the wiring substrate 3A and the bump 4A is achieved. The thermal stress in the part can be dispersed in the inorganic insulating structure 13A. As a result, the reliability of the electronic component 2A can be improved by reducing the thermal stress applied to the electrode 2cA formation region of the insulating coating 2bA and reducing the occurrence of cracks in the insulating coating 2bA.

  Further, the inorganic insulating structure 13A is preferably formed on the surface of the insulating coating 2bA, and in particular, as shown in FIG. 8, it is preferable to cover the entire lower surface of the electronic component 2A. As a result, the mechanical strength of the electronic component 2A can be increased and the reliability of the electronic component 2A can be improved.

(Electronic parts with bumps)
The bumped electronic component 16A shown in FIG. 9 is used to manufacture the mounting structure 1A described above. The bumped electronic component 16A includes an electronic component 2A, a bump 4A provided on the electrode 2cA of the electronic component 2A, and an inorganic insulating structure 13A provided continuously from the surface of the electronic component 2A to the surface of the bump 4A. And having.

  The bump 4A has the same configuration as the bump 4A included in the mounting structure 1A described above except that it is not connected to the wiring board 3A. The lower surface of the bump 4A has an exposed curved surface and is connected to the wiring board 3A.

  As described above, the inorganic insulating structure 13A is continuously provided from the surface of the electronic component 2A to the surface of the bump 4A. As a result, the above-described mounting structure 1A having excellent electrical reliability can be manufactured. Further, since it is possible to reduce the occurrence of cracks in the connection part between the electrode 2cA and the bump 4A and the electronic component 2A due to mechanical stress during transportation or thermal stress during mounting, mounting with excellent electrical reliability is possible. The structure 1A can be manufactured with high yield.

  Here, the inorganic insulating structure 13A is desirably formed on the side surface of the bump 4A. As a result, the lower surface of the bump 4A can be exposed.

  Next, a method for manufacturing the mounting structure 1A using the above-described bump electronic component 16A will be described.

(Production of electronic parts with bumps)
First, the electronic component 2A is prepared. Next, as in the step (3) of the first embodiment, bumps 4A are formed on the electrodes 2cA of the electronic component 2A. Next, similarly to the step (4) of the first embodiment, the inorganic insulating structure 13A is formed on the electronic component 2A. As described above, the bumped electronic component 16A can be manufactured.

(Production of mounting structure)
First, the wiring board 3A is prepared in the same manner as the steps (1) and (2) of the first embodiment. Next, as shown in FIG. 10, the bumped electronic component 16 </ b> A is mounted on the wiring board 3 </ b> A, similarly to the step (5) of the first embodiment. Next, as in the step (6) of the first embodiment, an underfill 14A is formed between the electronic component 2A and the wiring board 3A. As described above, the mounting structure 1A can be manufactured.

(Third embodiment)
Next, a mounting structure according to a third embodiment of the present invention will be described in detail based on FIG. In addition, description is abbreviate | omitted regarding the structure similar to 1st Embodiment and 2nd Embodiment mentioned above.

  As shown in FIG. 11, the third embodiment is different from the first and second embodiments in that the inorganic insulating structure 13B continuously extends from the surface of the electronic component 2B to the wiring substrate 3B via the surface of the bump 4B. Since it is formed, the mechanical strength at the connection portion between the electrode 2cB of the electronic component 2B and the bump 4B is increased, and the mechanical strength at the connection portion between the conductive layer 11B of the wiring board 3B and the bump 4B is increased. Can do. As a result, it is possible to reduce the occurrence of cracks at the upper and lower ends of the bumps 4B, thereby improving the electrical connection reliability between the electronic component 2B and the wiring board 3B, and improving the electrical reliability of the mounting structure 1B. Can be improved.

  The inorganic insulating structure 13B desirably covers the entire lower surface of the electronic component 2B and the entire upper surface of the wiring board 3B. As a result, the surface of the electronic component 2B and the surface of the wiring board 3B can be protected.

  Moreover, it is desirable that an underfill 14B is filled between the inorganic insulating structure 13B formed on the lower surface of the electronic component 2B and the inorganic insulating structure 13B formed on the upper surface of the wiring board 3B. As a result, peeling of the inorganic insulating structure 13B from the electronic component 2B and the wiring board 3B can be reduced.

  Next, a method for manufacturing the mounting structure 1B described above will be described.

(Production of mounting structure)
First, the wiring board 3B is prepared in the same manner as the steps (1) and (2) of the first embodiment. Next, as shown in FIG. 12A, the electronic component 2B is mounted on the wiring board 3B, as in the step (5) of the first embodiment. Next, as shown in FIG. 12B, the inorganic insulating structure 13B is formed on the electronic component 2B, the wiring board 3B, and the bumps 4B in the same manner as the step (4) of the first embodiment. Here, in the present embodiment, when applying the inorganic insulating sol, the inorganic insulating sol is applied between the electronic component 2B and the wiring board 3B so that the surface of the electronic component 2B passes through the surface of the bump 4B. The inorganic insulating structure 13B can be continuously formed over the wiring substrate 3B. Next, the underfill 14B is formed between the electronic component 2B and the wiring board 3B as in the step (6) of the first embodiment. As described above, the mounting structure 1B can be manufactured.

  In addition, when forming the inorganic insulating structure 13B, the inorganic insulating sol was applied while adjusting the coating amount, thereby forming the inorganic insulating structure 13B formed on the lower surface of the electronic component 2B and the upper surface of the wiring board 3B. A gap can be formed between the inorganic insulating structure 13B and the inorganic insulating structure 13B. Then, when forming the underfill 14B, an inorganic insulating structure 13B formed on the lower surface of the electronic component 2B and an inorganic insulating structure 13B formed on the upper surface of the wiring board 3B by filling the gap with a liquid resin. , The underfill 14B can be formed.

(Fourth embodiment)
Next, the mounting structure which concerns on 4th Embodiment of this invention is demonstrated in detail based on FIG. In addition, description is abbreviate | omitted regarding the structure similar to 1st Embodiment thru | or 3rd Embodiment mentioned above.

  As shown in FIG. 13, the third embodiment differs from the first to third embodiments in that bumps 4C are formed in a columnar shape. As a result, in the connection portion between the electrode 2cC and the bump 4C of the electronic component 2C and the connection portion between the conductive layer 11C and the bump 4C in the wiring substrate 3C, the connection area is increased and the surface of the bump 4C is recessed toward the inside. Therefore, it is possible to reduce the concentration of thermal stress at the connecting portion. As a result, the occurrence of cracks at the upper and lower ends of the bump 4C can be reduced, so that the electrical connection reliability between the electronic component 2C and the wiring board 3C is improved, and the electrical reliability of the mounting structure 1C is improved. Can be improved.

  Next, a method for manufacturing the mounting structure 1C described above will be described.

(Production of bumped wiring board)
First, the wiring board 3C is prepared in the same manner as the steps (1) and (2) of the first embodiment. Next, as shown in FIG. 14, in the step (3) of the first embodiment, after the columnar bumps 4C are formed on the conductive layer 11C, the bumps 4C are not heated and melted on the wiring substrate 3C. The inorganic insulating structure 13C is applied, and the bumps 4C and the inorganic insulating structure 13C are heated. As a result, the bump 4C can be heated and melted to improve the adhesive strength with the conductive layer 11C, and the inorganic insulating particles of the inorganic insulating structure 13C can be bonded together to improve the mechanical strength. And since it is supported by this inorganic insulating structure 13C, even if the bump 4C is heated and melted, it can be held in a columnar shape. As described above, the bumped wiring board 15C can be manufactured.

(Production of mounting structure)
Similarly to the first embodiment, the mounting structure 1C can be manufactured by mounting the electronic component 2C on the wiring board 3C and forming the underfill 14C between the electronic component 2C and the wiring board 3C. .

(Fifth embodiment)
Next, a mounting structure according to a fifth embodiment of the present invention will be described in detail with reference to FIG. 15a. In addition, description is abbreviate | omitted regarding the structure similar to 1st Embodiment thru | or 3rd Embodiment mentioned above.

  As shown in FIG. 15a, the third embodiment differs from the first to third embodiments in that the wiring board 3D has a solder resist layer 17D made of resin on its upper surface, and the inorganic insulating structure 13D is made of solder. It is continuously provided from the surface of the resist layer 17D to the surface of the bump 4D. As a result, it is possible to increase the mechanical strength at the connection portion between the bump portion 4D and the conductive layer 11D while using an existing manufacturing process. The solder resist layer 17D has a function of protecting the surface of the wiring board 3D, and a solder resist layer 17D formed of a resin material such as an epoxy resin, a cyanate resin, a polyimide resin, or a bismaleimide triazine resin may be used. it can.

  The insulating structure 13D is formed on a part of the upper surface of the wiring board 3D and is formed below the wide part of the bump 4D.

  The mounting structure according to the fifth embodiment can be manufactured in the same manner as the manufacturing method according to the first embodiment. In addition, after forming the conductive layer 11D in the step (2) of the first embodiment, the solder resist layer 17D can be formed by applying a resin and thermosetting it. Further, by adjusting the coating amount of the inorganic insulating sol in the step (4), the insulating structure 13D can be formed below a part of the upper surface of the wiring board 3D and the wide part of the bump 4D.

  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, the configuration in which the electronic component is a semiconductor element has been described as an example. However, for example, a circuit module made of ceramics, a crystal oscillator, a capacitor, or a CSP (chip scale package) may be used as the electronic component. I do not care.

  In the above-described embodiment, the configuration in which the base is made of resin has been described as an example. However, as the base, for example, a metal plate coated with resin or a ceramic made of ceramic may be used.

  In the above-described embodiments, the bumps of the wiring board with bumps and the bumps of the electronic parts with bumps have been described as an example in which the surface exposed from the inorganic insulating structure is a curved surface, but the exposed surface as a bump is flat. A thing may be used. Such bumps can be formed by, for example, heating and melting the bumps to form an inorganic insulating structure, and then polishing the upper surface of the bump together with the inorganic insulating structure.

  Further, as shown in FIG. 15b, the second embodiment and the fourth embodiment may be combined.

DESCRIPTION OF SYMBOLS 1 Mounting structure 2 Electronic component 2a Base material 2b Insulation film 2c Electrode 3 Wiring board 4 Bump 5 Core board 6 Wiring layer 7 Base body 8 Through-hole conductor 9 Insulator 10 Insulating layer 11 Conductive layer 12 Via conductor 13 Inorganic insulating structure 14 Underfill 15 Bumped wiring board T Through hole V Via hole

Claims (7)

A wiring board having an insulating layer and a conductive layer provided on the insulating layer;
A bump provided on the conductive layer and electrically connected to the conductive layer;
An inorganic insulating structure provided continuously from the surface of the wiring board to the surface of the bump , and
The wiring board with bumps , wherein the inorganic insulating structure has a plurality of inorganic insulating particles bonded to each other . In the wiring board with a bump according to claim 1,
The inorganic surface of the insulating structure is bumped wiring board, wherein concavely curved der Rukoto between the wiring substrate surface and the surface of the bump. In the wiring board with a bump according to claim 1,
The wiring board with bumps, wherein the inorganic insulating structure is provided along a circumferential direction of the bumps. In the wiring board with a bump according to claim 1,
The wiring board with bumps, wherein the inorganic insulating structure is continuously provided on a side surface of the bump from a lower end to an upper end of the bump. In the wiring board with a bump according to claim 1,
The wiring board with bumps, wherein the upper surface of the conductive layer consists only of a region provided with the bump and a region covered with the inorganic insulating structure. In the wiring board with a bump according to claim 1,
The bump has a first bump and a second bump adjacent to the first bump,
The wiring substrate with bumps, wherein the inorganic insulating structure is continuously provided from the surface of the first bump to the surface of the second bump through the surface of the wiring substrate. A bumped wiring board according to claim 1 ;
Mounting structure is characterized in that and an electronic component having a conductive layer and electrically connected to the electrode via the bump to the installed surface on the wiring board.

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