JP2013077699A - Wiring board, packaging structure and electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring board which responds to a request of improving connection reliability with electronic components.SOLUTION: A wiring board 1 includes a metal plate 2, and a wiring layer 5 having a plurality of insulation layers 3 and a conductive layer 4 disposed on the insulation layers 3 and disposed at least on one main surface of the metal plate 2. The insulation layers 3 include a first insulation layer 6 which is provided in contact with the one main surface of the metal plate 2 and has a resin whose thermal expansion coefficient in a plane direction is larger than that of the metal plate 2 as a main component, and a second insulation layer 7 which is laminated on the first insulation layer 6 and has thermal expansion coefficient in a plane direction smaller than that of the metal plate 2. The second insulation layer 7 contains a plurality of interconnected first particles composed of an inorganic insulation material, and a part of the first insulation layer 6 is interposed in a gap of the first particles. A difference in thermal expansion between the wiring layer 5 and the metal plate 2 can be reduced, and connection reliability with electronic components can be improved.

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), a mounting structure in which electronic components are mounted on the wiring substrate, and this The present invention relates to an electronic device having a mounting structure.

  2. Description of the Related Art In recent years, the amount of heat generated by electronic components has increased as the functionality of electronic components used in electronic devices has increased. Therefore, in order to efficiently release the heat generated in the electronic component, a metal plate may be used as the core material of the wiring board.

  Patent Document 1 describes a metal core substrate including a metal plate serving as a core material and a wiring layer made of a resin and a conductive layer coated on both the front and back surfaces of the metal plate.

  By the way, in general, the coefficient of thermal expansion is different between metal and resin, and when heat is applied to the metal core substrate, the difference in thermal expansion in the planar direction between the metal plate and the insulator increases. Stress is applied to the interface with the wiring layer, and this wiring may cause the wiring layer to peel off from the metal plate.

  As a result, the connection reliability of the metal core substrate is lowered, and as a result, the electrical reliability of the mounting structure may be lowered.

Japanese Patent Laid-Open No. 2002-353584

  It is an object of the present invention to provide a wiring board that meets the demand for improving the connection reliability with an electronic component, a mounting structure in which the electronic component is mounted on the wiring board, and an electronic device having the mounting structure. Is.

A wiring board according to an embodiment of the present invention includes a metal plate, a plurality of insulating layers, and a conductive layer disposed on the plurality of insulating layers, and a wiring disposed on at least one main surface of the metal plate. With layers,
The plurality of insulating layers of the wiring layer are provided in contact with the one main surface of the metal plate, and a first insulating layer mainly composed of a resin having a larger coefficient of thermal expansion in a planar direction than the metal plate. And a second insulating layer laminated on the first insulating layer so as to be in contact with the first insulating layer and having a smaller coefficient of thermal expansion in the planar direction than the metal plate, The second insulating layer includes a plurality of first particles connected to each other made of an inorganic insulating material, and a part of the first insulating layer is interposed in a gap between the plurality of first particles. It is characterized by this.

According to the wiring board according to one aspect of the present invention, the wiring layer disposed on one main surface of the metal plate has a first insulating layer having a larger coefficient of thermal expansion in the planar direction than the metal plate and the metal plate. A plurality of second insulating layers having a low coefficient of thermal expansion in the planar direction, the second insulating layer and the first insulating layer being stacked and connected to each other included in the second insulating layer Since the second insulating layer suppresses the thermal expansion of the first insulating layer by interposing a part of the first insulating layer in the gap between the first particles, the heat between the wiring layer and the metal plate The expansion difference can be reduced, the connection reliability with the electronic component can be improved, and the reliability of the wiring board can be improved. Moreover, it is possible to improve the electrical reliability of the mounting structure on which the electronic component is mounted and the electronic device having the actual structure.

It is sectional drawing of the wiring board which concerns on one Embodiment of this invention. It is an expanded sectional view of the 2nd insulating layer of the wiring board shown in FIG. It is sectional drawing of the other wiring board different from FIG. It is sectional drawing of the mounting structure which concerns on one Embodiment of this invention. It is sectional drawing of the mounting structure different from FIG. It is sectional drawing of the electronic device which concerns on one Embodiment of this invention. It is an expanded sectional view around a through hole formed in a metal plate included in a wiring board. It is an expanded sectional view of a notch part periphery formed in the metal plate which a wiring board has. It is sectional drawing explaining the process of preparing the metal plate which concerns on the wiring board shown in FIG. It is sectional drawing explaining the process of preparing the lamination sheet of the wiring board shown in FIG. It is sectional drawing explaining the process of producing the some insulating layer which concerns on the wiring board shown in FIG. It is sectional drawing explaining the process of preparing for producing the through-hole conductor which concerns on the wiring board shown in FIG. It is sectional drawing explaining the process of producing the through-hole conductor which concerns on the wiring board shown in FIG. It is sectional drawing explaining the process of producing the embedded insulator which concerns on the wiring board shown in FIG. It is sectional drawing explaining the process of producing the wiring layer which concerns on the wiring board shown in FIG. It is sectional drawing explaining the lamination | stacking process of the wiring layer which concerns on the wiring board shown in FIG. FIG. 7 is a cross-sectional view illustrating a process of removing a wiring layer related to the first mounting structure of the electronic device shown in FIG. 6. It is sectional drawing explaining the process of apply | coating the resin precursor which concerns on the 1st mounting structure of the electronic device shown in FIG. FIG. 7 is a cross-sectional view illustrating a process of manufacturing a recess and a second solder ball according to the first mounting structure of the electronic device shown in FIG. 6. It is sectional drawing explaining the process of preparing the 2nd mounting structure of the electronic device shown in FIG. FIG. 7 is a cross-sectional view illustrating a process for manufacturing the electronic device illustrated in FIG. 6.

<Wiring board>
Hereinafter, a wiring board according to an embodiment of the present invention will be described with reference to FIGS. 1, 2, and 7.

  A wiring board 1 shown in FIG. 1 has a metal plate 2 and a plurality of wiring layers 5 provided on both main surfaces of the metal plate 2 and each having a plurality of insulating layers 3 and conductive layers 4. The wiring layers 5 on both main surfaces of the metal plate 2 are electrically connected by a through-hole conductor 21 penetrating the metal plate 2.

  The metal plate 2 is made of a highly heat-conductive metal such as copper, aluminum, nickel, or an alloy thereof, and functions as a heat radiating member for releasing heat generated by electronic components provided on the wiring board 1. At the same time, it functions as a core material of the wiring board 1. Since the end face of the metal plate 2 is exposed, heat is favorably released from this end face. The metal plate 2 has a thermal conductivity of, for example, 50 W / m · K or more and 430 W / m · K or less, and a thermal expansion coefficient in each direction of, for example, 1 ppm / ° C. or more and 20 ppm / ° C. or less. .

  The thermal conductivity is measured by, for example, a laser flash method by a measuring method according to JIS C2141-1992. The coefficient of thermal expansion is measured by a measuring method according to JISK7197-1991 using a commercially available TMA (Thermo-Mechanical Analysis) apparatus.

  A plurality of wiring layers 5 are laminated on each of the main surfaces of the metal plate 2 described above (three layers in this embodiment), and each of the wiring layers 5 is disposed on the plurality of insulating layers 3 and the plurality of insulating layers 3. It has a layer 4. Specifically, the wiring layer 5 has a configuration in which the first insulating layer 6, the second insulating layer 7, and the conductive layer 4 are laminated in this order from the metal plate 2 side. Note that the number of stacked wiring layers 5 may be any number as long as it is one or more, and the number of stacked layers may be different on one main surface side or the other main surface side of the metal plate 2.

  The first insulating layer 6 has a base layer portion 6A and a filling portion 6B connected to the main surface of the base layer portion 6A and filled in a gap in the second insulating layer 7 described later. The base layer portion 6A provides insulation between the metal plate 2 and the conductive layer 4 and adhesion between the metal plate 2 and the second insulating layer 7, and the filling portion 6B includes the first insulating layer 6 and the second insulating layer 7. To improve adhesion.

  The first insulating layer 6 is formed mainly of a resin material. Examples of the resin material include epoxy resin, polyimide resin, acrylic resin, cyanate resin, fluorine resin, silicon resin, polyphenylene ether resin, and bismaleimide triazine resin. The thermal expansion coefficient in each direction of the first insulating layer 6 is set, for example, to 20 ppm / ° C. or more and 50 ppm / ° C. or less, and the Young's modulus is set to 0.5 GPa or more and 5 GPa or less. The Young's modulus is measured using, for example, Nano Indentor XP / DCM manufactured by MTS Systems.

  The second insulating layer 7 is composed of a large number of particles formed of an inorganic insulating material having a smaller coefficient of thermal expansion than the resin material of the first insulating layer 6. Such particles include first particles 8 and second particles 9 having a larger particle size than the first particles 8. For example, the particle size of the first particles 8 is 3 nm to 110 nm, for example. The particle size is 0.5 μm or more and 5 μm or less.

  Such first particles 8 and second particles 9 are arranged in a form in which a large number of first particles 8 having a small particle size are filled between the second particles 9. As shown in FIG. 2, the filled first particles 8 are bonded to each other, and the second particles 9 and a large number of first particles 8 arranged around the second particles 9 are bonded to each other, thereby The particles 9 are bonded together via a large number of first particles 8.

  The first particles 8 or the first particles 8 and the second particles 9 are bonded to each other at a part of the outer periphery while maintaining a certain particle shape. This is because ceramic particles grow so that the gaps between the particles disappear, as in the case of general ceramics sintering, and these particle-grown particles are bonded to most of the surface. The state is different. In the present embodiment, the second insulating layer 7 has a large number of particles bonded together while maintaining a certain particle shape in which gaps between a large number of particles in the insulating layer 7 do not disappear due to the bonding of a large number of particles. It remains in between. The gaps are connected to each other in a three-dimensional manner, and have a mesh shape, for example.

  In the gap between the particles in the second insulating layer 7, the filling portion 6B of the first insulating layer 6 is interposed. The filling portion 6B is bonded to the first particles 8 or the second particles 9, so that the first insulating layer 6 is not only bonded to the main surface of the second insulating layer 7. The first insulating layer 6 and the second insulating layer 7 are bonded to the inner surface of the gap between the second insulating layers 7, and the bonding area between the first insulating layer 6 and the second insulating layer 7 is increased. The layer 7 is firmly bonded. As a result, when heat is applied to the wiring board 1, even if the first insulating layer 6 having a larger thermal expansion coefficient than that of the metal plate 2 attempts to thermally expand, the second thermal expansion has a smaller thermal expansion coefficient. It is suppressed well by the insulating layer 7 and the thermal expansion coefficient becomes smaller than that of the first insulating layer 6. Therefore, the difference in thermal expansion between the wiring layer 5 and the metal plate 2 is reduced, the thermal stress at the interface between them is alleviated, and peeling between the metal plate 2 and the plurality of wiring layers 5 can be satisfactorily suppressed.

  Note that the second insulating layer 7 has a gap of 35% by volume or less, and the resin of the first insulating layer 6 is filled in the gap. Further, 65% by volume or more of the second insulating layer 7 is occupied by the first particles 8 and the second particles 9, of which the first particles 8 are contained by 20 to 40% by volume, and the second particles 9 is contained in an amount of 60% by volume to 80% by volume. Examples of the inorganic insulating material constituting the first particle 8 and the second particle 9 include silicon oxide, aluminum oxide, magnesium oxide, calcium oxide, and the like. The thermal expansion coefficient in each direction of the second insulating layer 7 formed of these materials is set to, for example, 0.6 ppm / ° C. or more and 3 ppm / ° C. or less, and the Young's modulus is set to 100 GPa or more and 150 GPa or less.

  In addition, the second insulating layer 7 has a higher Young's modulus than the first insulating layer 6 and is sufficiently rigid. Therefore, as shown in FIG. Even if it is formed thinner than the layer 6, it is possible to suppress the thermal expansion of the first insulating layer 6 without destroying the second insulating layer 7 due to the thermal stress caused by the thermal expansion difference between the resin and the particles. it can. As a result, the wiring layer 5 can be reduced in thickness, and heat of electronic components mounted on the wiring board 5 can be efficiently conducted to the metal plate 2 to be radiated, thereby improving the reliability of the wiring board. Improve.

  The second insulating layer 7 includes second particles 9 having a larger particle size than the first particles 8. Therefore, even if a crack generated by breaking the bond between the first particles 8 reaches the second particle 9, the crack is bypassed along the surface of the second particle 9 having a large particle size. Since it will elongate, a large amount of energy is required to elongate the crack. As a result, the extension of cracks can be reduced and the second insulating layer 7 can be satisfactorily prevented from being destroyed.

  The first particles 8 and the second particles 9 may be formed of the same material or different materials. However, when the first particles 8 and the second particles 9 are formed of the same material, the bonding between the particles becomes stronger. This is preferable in order to suppress cracks generated in the insulating layer 7.

  The conductive layer 4 is partially disposed on each second insulating layer 7 and is formed of a conductive material such as copper. In addition, the conductive layers 4 of the wiring layers 5 are arranged with a space therebetween in the thickness direction, and the upper and lower conductive layers 4 are electrically connected by via conductors 18. The conductive layer 4 and the via conductor 18 are made of a conductive material such as lead, tin, silver, gold, copper, zinc, bismuth, indium, or aluminum.

  On the other hand, the first and second insulating layers 6 and 7 of the wiring layer 5 in contact with the metal plate 2 are provided with a plurality of through holes 19 penetrating in the thickness direction as shown in FIG. The through-hole conductor 21 is provided in the through-hole 19 through the through-hole insulating layer 20.

As shown in FIG. 7, the through-hole conductor 21 is formed of a cylindrical body filled with an embedded insulator 22, and is formed of a conductive material such as copper, silver, gold, nickel, or chromium, and the metal plate 2. And formed on the inner surface of the through-hole insulating layer 20 in the through-hole 19 that penetrates the pair of insulating layers 3 disposed on both main surfaces of the metal plate 2 and electrically connects the wiring layers 5 to each other. ing.

  The through-hole insulating layer 20 is intended to satisfactorily prevent the through-hole conductors 21 and the metal plate 2 from coming into contact with each other and the through-hole conductors 21 being electrically short-circuited. The through-hole insulating layer 20 and the embedded resin 22 are made of a resin material such as epoxy resin, polyimide resin, acrylic resin, cyanate resin, fluorine resin, silicon resin, polyphenylene ether resin, or bismaleimide triazine resin.

<Manufacturing method of wiring board>
Next, the manufacturing method of the wiring board 1 mentioned above is demonstrated using FIGS. 9-16.

  (1) First, as shown in FIG. 9, a metal plate 2 is prepared.

  The metal plate 2 has a plurality of through holes for electrically connecting the wiring layers 5 laminated on both main surfaces of the metal plate 2 to a plate body made of a highly heat conductive material such as copper, aluminum or nickel. 19 is formed by a conventionally known etching technique or the like.

  In addition, in order to improve the adhesive strength between the metal plate 2 and the plurality of laminated sheets 3 ′, the surface of the metal plate 2 may be roughened. The surface of the metal plate 2 is roughened by forming fine irregularities on the surface of the metal plate 2 with, for example, an etching solution containing formic acid as a main component.

  (2) Next, as shown in FIG. 10, from the second insulating layer 7, the uncured resin sheet 6 ′ corresponding to the first insulating layer 6, and the conductive support 27 that supports them. A pair of laminated sheets 3 ′ is prepared.

  The laminated sheet 3 ′ is produced by the following method. First, an inorganic insulating sol containing a large number of first particles 8 and second particles 9 is applied onto a conductive support 27 such as a copper foil, and heated at, for example, 150 ° C. to 230 ° C. for 2 hours to thereby form an inorganic insulating material. The sol is dried to form the second insulating layer 7 on the support 17. Since this inorganic insulating sol includes a large number of first particles 8 whose particle size is set in a minute range, for example, 110 nm or less, the atoms on the surface of the first particles 8 are heated by about 150 ° C. to 230 ° C. When activated, the first particles 8 and the second particles 9 and the first particles 8 are bonded to each other, whereby the second insulating layer 7 in which the particles 8 and 9 are firmly bonded to each other is formed. Note that a gap is formed between the particles in the second insulating layer 7.

  On the other hand, in order to prepare the resin sheet 6 'separately, a varnish in which an uncured resin is dissolved in a solvent is applied onto a PET film and dried to form the resin sheet 6' in the form of a PET film. In addition, uncured is the state of A-stage or B-stage according to ISO472: 1999.

  Then, for example, the resin sheet 6 ′ is bonded so as to be in contact with the second insulating layer 7 by a vacuum laminator, a roll laminator, or a vacuum press, and then the PET film is peeled off from the resin sheet 6 ′, whereby the laminated sheet 3 ′. Is produced. In this bonding step, the resin sheet 6 ′ is heated by heating in the temperature range (above the glass transition temperature of the resin and less than the polymerization start temperature) that is pressurized at the time of bonding and the resin is not thermally cured. The fluidized resin is fluidized, and the fluidized resin is filled in the gaps of the second insulating layer 7.

  The conductive support 27 becomes a part of the through-hole conductor 12 by patterning later.

  (3) Next, as shown in FIG. 11, in a state where a pair of laminated sheets 3 ′ are laminated on both main surfaces of the metal plate 2, both main surfaces of the laminate are heated while being pressed.

  The laminated sheet 3 ′ is laminated so that the resin sheet 6 ′ is in contact with the metal plate.

  The heating is performed at a temperature of 170 ° C. to 220 ° C., for example, and the resin sheet 6 ′ is thermoset by such heating. When the heating temperature of the resin sheet 6 ′ exceeds the glass transition temperature, the resin is fluidized, and the fluidized resin is filled in the through hole 19 of the metal plate 2. When the heating further proceeds and the heating temperature exceeds the polymerization start temperature of the resin, the filled resin is thermoset. Of the heat-cured resin, the resin inside the through-hole is processed in a later step to form the through-hole insulating layer 20, and the resin on both main surfaces of the metal plate 2 is the first insulating material. The resin that forms the base layer portion 6 </ b> A of the layer 6 and fills the gap between the second insulating layers 7 becomes the filling portion 6 </ b> B of the first insulating layer 6.

  (4) Subsequently, as shown in FIG. 12, a through hole is formed through the conductive support 27, the first insulating layer 6, the second insulating layer 7, and the resin filled in the through hole 19.

  The through hole is formed by, for example, drilling or laser processing.

  (5) Next, as shown in FIG. 13, a conductive material is applied to the inner surface of the through hole and the entire upper surface of the conductive support 27, and this is applied to a conventionally known photolithography technique, etching technique, etc. Through-hole conductors 21 are formed by patterning by the above.

  The conductive material is deposited on the inner wall of the through hole by, for example, electroless plating or electroplating.

  (6) Subsequently, as shown in FIG. 14, a resin material or the like is filled in the cylindrical through-hole conductor 21 to form a buried insulator 22.

  The embedded insulator 22 is formed by filling an uncured resin having fluidity on the inner surface of the through-hole conductor 21 and thermosetting it.

  (7) Next, as shown in FIG. 15, the conductive layer 4 is formed on the second insulating layer 7 so as to cover the end face of the through-hole conductor 21 and the embedded insulator 22, and the first insulating layer 6. Then, the wiring layer 5 composed of the second insulating layer 7 and the conductive layer 4 is formed.

  The conductive layer 4 is formed in a predetermined pattern by, for example, a conventionally known semi-additive method or subtractive method.

  (8) Thereafter, as shown in FIG. 16, the wiring layers 5 are sequentially laminated by sequentially repeating the steps (2), (3) and (7). Further, if necessary, via conductors 18 for electrically connecting the conductive layers 4 separated from each other are formed in the wiring layer 5.

  The via conductor 18 irradiates the first insulating layer 6 and the second insulating layer 7 with laser light at a timing between the above (3) and (7), for example, by a YAG laser device or a carbon dioxide gas laser device, A via hole penetrating the first insulating layer 6 and the second insulating layer 7 is formed, and a conductive material is deposited in the via hole by a well-known semi-additive method or a subtractive method. .

  The wiring board 1 is completed through the above steps.

<Mounting structure>
Next, a mounting structure in which electronic components are mounted on a wiring board shown in FIG. 4 will be described.

  The mounting structure 17 includes the wiring board 1A, the electronic component 10 mounted on one main surface of the wiring board 1A via the first solder balls 14, and the wiring board 1A and the first electronic component 10 between them. The underfill 26 is provided.

  The basic configuration of the wiring board 1A in the present embodiment is the same as that of the wiring board 1 described above, but in the wiring board 1A, the metal plate 2 is exposed so that a part of the conductive layer 4 of the wiring layer 5 is exposed. The first and second solder resist layers 24 and 25 are formed on both main surfaces of the first and second conductive layers 4 exposed from the second solder resist layer 25, and the first solder resist layers 24 and 25 are connected to the mother board. 2 is different from the wiring board 1 in that two solder balls 15 are arranged. The first and second solder resist layers 24 and 25 are formed when the first and second solder balls 14 and 15 are mounted when the electronic component is mounted on the wiring board 1A and when the wiring board 1A is mounted on the mother board. This is for suppressing wet spreading on the conductive layer 4 and preventing the solder from adhering to the conductive layer 4 other than a desired portion.

  Examples of the first electronic component 10 mounted on the wiring substrate 1A include an LSI and a memory chip. The first electronic component 10 is mounted on the wiring substrate 1A by flip chip mounting or the like via a plurality of first solder balls 14, for example.

  The underfill 26 is filled between the wiring board 1A and the first electronic component 10 and protects the connection surface between the wiring board 1A and the first electronic component 10, and is, for example, epoxy resin or polyimide. It is formed of a resin material such as resin.

<Modification of Mounting Structure 17>
As a modified example of the mounting structure 17, a mounting structure 17A as shown in FIG. 5 is shown.

  The mounting structure 17A is different from the mounting structure 17 in the configuration of the wiring board. Specifically, in the wiring board 1A of the mounting structure 17, the wiring layers 5 are provided on both main surfaces of the metal plate 2, whereas in the wiring board 1B of the mounting structure 17A in this example, the metal is The wiring layer 5 is provided only on one main surface of the plate 2, and the other main surface of the metal plate 2 is different in that it is exposed to the atmosphere. Further, in the wiring board 1A, the second solder balls 13B are arranged on the other main surface of the metal plate 2, whereas in the wiring board 1B of this example, the second solder balls 13B are disposed around the first electronic component 10 in the second area. It differs from the mounting structure 17 in that the solder balls 15 are arranged.

  In this example, in addition to the effects similar to those of the mounting structure 17 in such a configuration, the other main surface of the metal plate 2 is exposed in the atmosphere. There is no interruption in heat transfer, and heat is radiated well to the outside through the other main surface, so that the heat radiation efficiency is further improved as compared with the mounting structure 17.

<Electronic device>
Next, the electronic device 29 shown in FIG. 6 will be described.

In the electronic device 29 shown in FIG. 6, the first mounting structure 17B in which the first electronic component 10 is mounted on one main surface of the wiring board 1C and the second electronic component 11 on the circuit board 12 are mounted. And a second mounting structure 17C. The first mounting structure 17B is arranged so as to cover the second electronic component 11 included in the second mounting structure 17C, and the first mounting structure 17B and the second mounting structure 17C are the second solder. It is electrically connected via a ball 15.

  The first mounting structure 17B has the same basic configuration as the mounting structure 17 described above, but the configuration of the wiring board is different. Specifically, in the wiring board 1C of the first mounting structure 17B, the wiring layer 5 provided on the other main surface of the metal plate 2 has a recess, and a part of the metal plate 2 is exposed from the recess. This is different from the wiring board 1 </ b> A of the mounting structure 17.

  On the other hand, in the second mounting structure 17C, as described above, the second electronic component 11 is mounted on one main surface of the circuit board 12, and the other main surface of the circuit board 12 is connected to the mother boat. A third solder ball 16 is provided. The circuit board 12 functions as a support member for supporting the second electronic component 11 and also functions as a connection member for electrically connecting the second electronic component 11 to a mother board (not shown). The solder ball 16 is mounted on the mother board.

  The circuit board 12 is not limited to a specific configuration as long as the above-described function as the support member and the function as the connection member are satisfied, but between the first mounting structure 17B and the second mounting structure 17C. In order to relieve the applied thermal stress, it is preferable that the circuit board 12 has a configuration in which the wiring layers 5 included in the wiring boards 1 to 1C are sequentially laminated. As a result, the difference in thermal expansion between the circuit board 12 and the wiring board 1 can be reduced.

  Examples of the second electronic component 11 include an LSI and a memory chip that generate a large amount of heat, as in the case of the first electronic component 10.

  The second electronic component 11 of the second mounting structure 17C is accommodated in the recess of the wiring board 1C of the first mounting structure 17B, and is connected to the metal plate 2 exposed from the recess through the adhesive 28. Has been. As a result, the heat generated by the second electronic component 11 can be favorably released through the metal plate 2.

  Examples of the adhesive 28 include a highly heat-conductive adhesive material, for example, an uncured resin material that is highly filled with metal powder such as silver or copper in an amount of about 50 volume% to 70 volume%.

  Further, a space is formed between the first mounting structure 17B and the second mounting structure 17C because the height of the second solder ball 15 is larger than the thickness of the solder resist layer 25. ing. Although this space may be filled with a resin material or the like, the heat radiation efficiency can be further improved by introducing air without filling it with the resin material and circulating the air.

<Method for Manufacturing Electronic Device>
Next, a method for manufacturing the electronic device 29 described above will be described.

  (1) First, the first mounting structure 17B is prepared.

  Specifically, the first mounting structure 17B is manufactured as follows. First, the wiring board 1 described above is prepared, and a part of the metal plate 2 is removed by removing a part of the wiring layer 5 by a conventionally known sandblasting method on the other main surface of the metal plate 2 of the wiring board 1. Expose (see FIG. 17).

  Next, a film-like resin precursor 25 ′ corresponding to the solder resist layer 25 is attached so as to cover the exposed surface of the metal plate 2 (see FIG. 18).

Subsequently, by removing a part of the resin precursor 25 ′ by a conventionally known photolithography technique or the like, a recess is formed in a part of the wiring layer 5 so as to expose a part of the metal plate 2 again. Then, a part of the conductive layer 4 is exposed.

  Then, a second solder ball 15 is formed on a part of the exposed conductive layer 4 by, for example, a screen printing method, and the first electronic component 10 is mounted to produce the first mounting structure 17B (see FIG. 19).

  (2) Next, as shown in FIG. 20, a second mounting structure 17C is prepared.

  The second mounting structure 17 </ b> C is manufactured by first preparing the circuit board 12 and mounting the second electronic component 11 on the circuit board 12. As the circuit board 12, a conventionally known organic wiring board is used.

  (3) Finally, as shown in FIG. 21, the first mounting structure 17B and the second mounting structure 17C are connected.

  For the connection between the first mounting structure 17B and the second mounting structure 17C, first, the adhesive 28 is applied to the connection surface of the second electronic component 11 of the second mounting structure 17C with the first mounting structure 17B. Apply.

  Next, the first mounting structure 17B is aligned on the second mounting structure 17C so that the second electronic component 11 of the second mounting structure 17C is accommodated in the recess of the first mounting structure 17B. And place it.

  Subsequently, by heating the laminated body of the first mounting structure 17B and the second mounting structure 17C, the second solder balls 15 included in the first mounting structure 17B are reflowed, and the adhesive 28 is heated. By curing, the first mounting structure 17B and the second mounting structure 17C are connected, whereby the electronic device 29 is completed.

  Note that the present invention is not limited to the above-described embodiment, and various modifications and improvements can be made without departing from the spirit of the present invention.

  For example, in the wiring boards 1 to 1C according to the above-described embodiment, the electrical connection provided on both main surfaces of the metal plate 2 is performed via the through-hole conductor 21, but at the end of the metal plate 2. You may electrically connect through the provided wiring 23. FIG. The wiring 23 provided on the end face of the metal plate 2 may be provided on the inner surface of the notch by forming a notch on the end face of the metal plate 2. As shown in FIG. 9, the wiring 23 provided on the inner surface of the notch portion of the metal plate 2 is provided on the inner surface of the notch portion via a resin body, and instead of the through-hole conductor 21, both wires of the metal plate 2 are provided. The main surface is electrically connected. The wiring 23 provided on the inner surface of the notch is formed by cutting a mother board for taking a large number of wiring boards 1 to 1C so as to divide the through-hole conductor 21 into almost half. If the wiring 23 is formed by such a method, the volume of the resin portion provided on the metal plate 2 is reduced as compared with the case where the through-hole conductor 21 is formed, and the heat dissipation efficiency can be further improved. This is preferable.

  In the electronic device 29 described above, the second electronic component 11 is connected to the metal plate 2 via the adhesive 28, but the adhesive may not be provided. In this case, by bringing the second electronic component 11 into contact with the metal plate 2, the heat of the second electronic component 11 can be favorably transferred to the metal plate 2.

DESCRIPTION OF SYMBOLS 1, 1A, 1B, 1C Wiring board 2 Metal plate 3 Insulating layer 3 'Laminated sheet 4 Conductive layer 5 Wiring layer 6 1st insulating layer 6' Resin sheet 6A Base layer part 6B Filling part 7 2nd insulating layer 8 1st Particle 9 Second particle 10 First electronic component 11 Second electronic component 12 Electronic device 13 Circuit board 14 First solder ball 15 Second solder ball 16 Third solder ball 17, 17A Mounting structure 17B First Mounting structure 17C Second mounting structure 18 Via conductor 19 Through hole 20 Through hole insulating layer 21 Through hole conductor 22 Embedded insulator 23 Wiring 24 First solder resist layer 25 Second solder resist layer 25 'Precursor 26 Under Fill 27 Support 28 Adhesive 29 Electronic device

Claims (9)

Comprising a metal plate, a plurality of insulating layers and a conductive layer disposed on the plurality of insulating layers, and a wiring layer disposed on at least one main surface of the metal plate,
The plurality of insulating layers of the wiring layer are provided in contact with the one main surface of the metal plate, and a first insulating layer mainly composed of a resin having a larger coefficient of thermal expansion in a planar direction than the metal plate. And a second insulating layer laminated on the first insulating layer so as to be in contact with the first insulating layer and having a smaller coefficient of thermal expansion in the planar direction than the metal plate,
The second insulating layer includes a plurality of first particles connected to each other made of an inorganic insulating material, and a part of the first insulating layer is interposed in a gap between the plurality of first particles. A wiring board characterized by comprising: The wiring board according to claim 1,
The wiring board, wherein the wiring layer is disposed only on the one main surface of the metal plate. The wiring board according to claim 1,
The wiring board according to claim 1, wherein the second insulating layer further includes second particles made of a plurality of inorganic insulating materials having a particle diameter larger than that of the first particles connected to each other through the first particles. The wiring board according to claim 1,
The wiring board, wherein the thickness of the second insulating layer is smaller than the thickness of the first insulating layer. The wiring board according to claim 1;
A mounting structure comprising an electronic component mounted on the wiring layer of the wiring board. The wiring board according to claim 1, a circuit board on which the wiring board is mounted, and an electronic component mounted on the circuit board and disposed between the wiring layer and the circuit board. In electronic devices
The electronic device is characterized in that at least a part of the other main surface of the metal plate is exposed and the electronic component is connected to the exposed portion. The electronic device according to claim 6.
The electronic device is connected to the exposed portion of the metal plate via an adhesive. The electronic device according to claim 6.
The electronic device is in contact with an exposed portion of the metal plate. The electronic device according to claim 8.
The metal plate has the wiring layers on both main surfaces, a notch portion on a side surface, an insulator formed on an inner surface of the notch portion, and formed on the insulator, the metal plate An electronic device, further comprising: a conductor for electrically connecting the wiring layers disposed on both main surfaces of the plate.

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