JP2009021468A - Heat conductive printed wiring board, heat conductive prepreg used therefor and method of manufacturing the same, and method of manufacturing the heat conductive printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printed wiring board which hardly cracks even when its heat conductivity is increased. <P>SOLUTION: At a center part of a heat conductive printed wiring board 10, a core layer 18 is formed by laminating one or more internal composite layers 12 including glass fiber 17 and one or more internal electrodes 14 respectively, and further an external layer composite layer 11 including no glass fiber 17 is formed on one or more surfaces of the core layer 18, thereby obtaining the heat conductive printed wiring board 10 which has high heat conductivity and hardly cracks. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a heat transfer printed wiring board used for mounting various electronic components such as power semiconductors and high-performance semiconductors that require heat dissipation at high density, a heat transfer prepreg used therefor, and a method for manufacturing the same. And a method for manufacturing a heat transfer printed wiring board.

  2. Description of the Related Art Conventionally, printed wiring boards for mounting electronic components have been obtained by laminating, integrating, and curing a plurality of prepregs made of glass epoxy resin and copper foil. Furthermore, with the miniaturization and high performance of equipment, heat generation of electronic components often becomes a problem, and a printed wiring board having heat dissipation (or heat transfer) is required. Next, the heat transfer printed wiring board will be described.

  For example, using a crystalline epoxy resin with improved thermal conductivity, a material with improved thermal conductivity has been proposed. An example will be described with reference to FIG. That is, FIGS. 8A and 8B are cross-sectional views illustrating a state in which a crystalline polymer having both mesogenic groups is oriented using a magnetic field to increase the thermal conductivity (see, for example, Patent Document 1). ).

  8A and 8B, magnetic force lines indicated by arrows 2 are generated between a plurality of magnets 1 (for example, permanent magnets as magnetic field generating means). Then, a resin 4 (for example, a crystalline epoxy resin in a liquid state before being cured) placed in the mold 3 is placed between the magnetic field lines indicated by the arrows 2, and the resin 4 is thermally cured in this magnetic field. . FIG. 8A shows a state in which a magnetic field is applied in a direction perpendicular to the resin 4, and FIG. 8B shows a state in which a magnetic field in a parallel direction is applied.

  However, in order to orient the crystalline epoxy which is originally hard to be magnetized, it is cured for 10 minutes to 1 hour in the mold 3 heated to a temperature of 150 to 170 ° C. in a high magnetic field with a magnetic flux density of 5 to 10 terraces. Special processing is required. The crystalline epoxy resin thus formed may have anisotropy in thermal conductivity and physical strength (for example, bending strength). As a result, the prepreg and printed wiring board produced using such a crystalline epoxy resin have direction dependency (or anisotropy), and thus flexibility is reduced (for example, bending resistance is reduced, Or, it is easy to break when bent.

  On the other hand, in order to increase the thermal conductivity of the prepreg, it has been proposed to add an inorganic filler at a high density. However, a sheet-like prepreg to which an inorganic filler is added at a high density is hard and difficult to bend, and may be broken only by being wound. Moreover, in order to increase the quantity of the inorganic filler with respect to the glass fiber with low heat conductivity, it is necessary to make a glass woven fabric thin, and an intensity | strength falls.

  And the printed wiring board itself obtained by laminating and curing the prepreg which is hard and difficult to bend easily breaks when bent. Therefore, a problem may occur when electronic components are mechanically mounted on such a printed wiring board or when the printed wiring board is mounted on a device after mounting.

  In response to these problems, proposals have been made to improve both thermal conductivity and handleability (for example, workability of prepreg sheets and bending resistance).

  FIG. 9 is a cross-sectional view showing an example of a conventional heat transfer prepreg with improved bendability, which is proposed in Patent Document 2, for example. In FIG. 9, a conventional heat transfer prepreg 5 includes glass fibers 6, a thermosetting resin layer (inner layer portion) 7, and an inorganic filler-added thermosetting resin layer (outer layer portion) 8. Here, the inorganic substance is added to increase the thermal conductivity of the inorganic filler-added thermosetting resin layer 8 constituting the outer layer portion. And as shown in FIG. 9, the inorganic filler addition thermosetting resin layer 8 comprises the outer layer part of the conventional heat-transfer prepreg 5, and the part (what is called inner layer part) which covers the glass fiber 6 is an inorganic filler. The thermosetting resin layer 7 is not included. Due to the presence of the glass fiber 6 layer that is not impregnated with the inorganic filler, the rigidity of the glass fiber 6 does not increase (or the flexibility of the glass fiber 6 is maintained), and the sheet-like conventional heat transfer prepreg 5 is provided. This improves the bendability (or flexibility).

However, in the configuration shown in FIG. 9, the thermal conductivity in the thickness direction of the conventional prepreg 5 may be hindered. This is because the thermal conductivity of the glass fiber 6 and the thermosetting resin layer 7 is lower than that of the inorganic filler-added thermosetting resin layer 8 in the outer layer portion.
JP 2004-225054 A Japanese Patent Laid-Open No. 3-17134

  Thus, in the case of the conventional printed wiring board, when it was going to raise the thermal conductivity of a printed wiring board, there existed a subject that it would become easy to break when it bends.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a heat transfer printed wiring board that increases the thermal conductivity of the printed wiring board and is not easily broken even when bent, a heat transfer prepreg used therefor, and a method for manufacturing the same.

  In order to achieve this object, the present invention has a thermal conductivity of 0.5 W / (m · K) or higher and 20 W / laminated by laminating a glass woven fabric, a composite layer impregnating the glass woven fabric, and an internal electrode. The heat transfer printed wiring board includes a core layer of (m · K) or less, an outer composite layer formed on the core layer, and a surface wiring pattern formed on the outer composite layer.

  According to the heat transfer printed wiring board of the present invention, the heat transfer prepreg used in the heat transfer printed wiring board and the method for manufacturing the heat transfer printed wiring board, and the method for manufacturing the heat transfer printed wiring board, the core layer serving as the central portion of the heat transfer printed wiring board is cured. It is mounted on the surface layer wiring pattern by forming a surface layer wiring pattern on the core layer through an outer composite layer on the core layer with a thermal conductivity of 3 W / (m · K) to 20 W / (m · K). The heat generated in the electronic component diffuses in the planar direction through the outer composite layer or in the thickness direction through the inner composite layer.

  In addition, by using glass fiber for the core layer, it is difficult to break even if the heat transfer printed wiring board is bent, so it is common to use conventional glass epoxy resin even though it is a heat transfer printed wiring board with excellent heat transfer It can be handled in the same way as the printed wiring board.

  As a result, the temperature of the semiconductor or the like mounted on the heat transfer printed wiring board is reduced, and heat countermeasures are facilitated. In addition, electronic components and the like can be mounted at high density, and miniaturization and high performance of liquid crystal televisions, plasma televisions, and various electronic devices can be achieved.

(Embodiment 1)
Hereinafter, the heat-transfer printed wiring board in Embodiment 1 of this invention is demonstrated.

  1 is a cross-sectional view of a heat transfer printed wiring board according to Embodiment 1. FIG. In FIG. 1, 10 is a heat transfer printed wiring board, 11 is an outer composite layer, 12 is an inner composite layer, 13 is a via portion, 14 is an internal electrode, 15 is a surface layer wiring pattern, 16 is a blind via, 17 is a glass fiber, Reference numeral 18 denotes a core layer.

  First, a description will be given with reference to FIG. As shown in FIG. 1, the heat transfer printed wiring board 10 described in the first embodiment includes a plurality of glass fibers 17, an inner composite layer 12 impregnated therein, and an internal electrode 14 in the center. It has the core layer 18 laminated | stacked. An outer composite layer 11 and a surface wiring pattern 15 formed on the outer composite layer 11 are formed on the core layer 18.

  In FIG. 1, the via portion 13 formed in the core layer 18 is an interlayer connection between a plurality of layers of internal electrodes 14. The glass fiber 17 may be a woven fabric or a non-woven fabric.

  Moreover, the thermal conductivity of the core layer 18 shown in FIG. 1 is 0.5 W / (m · K) or more and 20 W / (m · K) or less, and the thermal conductivity of the outer composite layer 11 formed on the core layer 18 is 3 W. / (M · K) or more and 20 W / (m · K) or less is desirable. When the thermal conductivity of the core layer 18 is less than 0.5 W / (m · K), the heat transfer effect through the core layer 18 may be reduced. Moreover, when the thermal conductivity of the core layer 18 is 20 W / (m · K) or more, the core layer 18 may become expensive. The heat transfer effect in the planar direction or thickness direction via the outer composite layer 11 may be reduced. Also, it is technically and materially difficult to make the thermal conductivity of the outer composite layer 11 larger than 20 W / (m · K). In addition, it is desirable to make the thermal conductivity of the outer composite layer 11 larger than the thermal conductivity of the inner composite layer 12 constituting the core layer 18. By making the thermal conductivity of the outer composite layer 11 larger than that of the inner composite layer 12, heat generated in an electronic component (not shown) that generates heat can be effectively transferred.

  As the core layer 18, it is desirable to use the inner composite layer 12 containing the glass fiber 17. By incorporating the glass fiber 17, the effect of increasing the proof stress of the core layer 18 (being difficult to break even when bent) can be obtained.

  The internal electrode 14 formed on the core layer 18 and the surface wiring pattern 15 formed on the outer composite layer 11 are preferably connected via a blind via 16 formed on the outer composite layer 11. By doing so, the surface wiring pattern 15 can be made into a fine pattern, and various electronic components (including not only electronic components that generate heat but also general electronic components) can be surface-mounted at high density.

  Next, the heat transfer mechanism of the heat transfer printed wiring board 10 shown in FIG. 1 will be described with reference to FIG. FIG. 2 is a cross-sectional view illustrating the heat transfer mechanism of the heat transfer printed wiring board 10. In FIG. 2, 19 is an electronic component in which heat generation from a power semiconductor or the like is an issue, 20 is a solder portion, and corresponds to a portion where the electronic component 19 is mounted on the surface layer wiring pattern 15. Bump mounting, wire mounting, or the like may be used. Reference numeral 21 denotes an arrow. In FIG. 2, the arrow 21 indicates how heat is diffused.

  In FIG. 2, the heat generated in the electronic component 19 spreads to the surface wiring pattern 15 and the outer composite layer 11 through the solder portion 20 as indicated by an arrow 21 and is diffused and radiated.

  Here, by using a material having high thermal conductivity such as copper as the surface layer wiring pattern 15, it is possible to obtain an effect of increasing the heat conductivity and reducing the wiring resistance.

(Embodiment 2)
In the second embodiment, an example of a method for manufacturing the heat transfer printed wiring board 10 described in the first embodiment will be described. 3-6 is sectional drawing explaining an example of the manufacturing method of the heat-transfer printed wiring board 10. FIG.

  FIG. 3 is a cross-sectional view illustrating an example of a method for manufacturing a heat transfer prepreg used for manufacturing the heat transfer printed wiring board 10. In FIG. 3, 22 is a heat transfer prepreg, 23 is equipment, 24 is a tank, and 25 is a member.

  First, as shown in FIG. 3, the glass woven fabric (or glass nonwoven fabric) formed from the glass fibers 17 is set in the equipment 23 and sent as shown by an arrow 21a. Here, the equipment 23 is a part of a manufacturing apparatus for the heat transfer prepreg 22 and corresponds to, for example, a roll portion. Then, the glass fiber 17 is immersed in the member 25 set in the tank 24. After impregnating the glass fiber 17 with the member 25, the excess member 25 is removed by the equipment 23, and the member 25 is semi-cured (or half-shown in FIG. 4A described later) through a dryer or the like. A cured resin body 26) and a heat transfer prepreg 22 are used.

  Glass fiber 17 includes not only glass woven fabric but also glass nonwoven fabric. Since the aperture ratio can be increased by using a glass nonwoven fabric as the glass fiber 17 in addition to the glass woven fabric, the heat transfer property of the heat transfer prepreg 22 can be increased. Further, when a glass woven fabric is used, an effect of increasing the strength in the XY direction of the heat transfer prepreg 22 can be obtained, so that an effect of increasing its dimensional stability and mechanical strength can be obtained. By incorporating the glass fiber 17 in the heat transfer prepreg 22 in this manner, the Z direction (thickness direction) of the heat transfer prepreg 22 can be made difficult to extend by making the heat transfer prepreg 22 difficult to shrink in the XY direction. As a result, the effect of improving the reliability of the printed wiring board in the Z direction (for example, the connection reliability of the through hole portion) can be obtained. This is because the thermal expansion in the Z direction is suppressed.

  The thickness of the heat transfer prepreg 22 is preferably 20 microns or more and less than 500 microns. When the thickness of the heat transfer prepreg 22 is less than 20 microns, the mechanical strength (for example, tensile strength) of the heat transfer prepreg 22 (or the heat transfer printed wiring board 10 formed by curing the heat transfer prepreg 22) may be affected. There is. In addition, when the thickness exceeds 500 microns, handling (for example, difficult to wind) may be affected.

  In addition, it is desirable to make the thickness of the heat transfer prepreg 22 thicker than the thickness of the woven or non-woven fabric composed of the glass fibers 17. This is because the heat transfer prepreg 22 is made thicker than the thickness of the glass woven fabric or non-woven fabric made of the glass fibers 17, so that the thickness of the superscript resin (so-called extra semi-cured resin body covering the surface of the glass fibers 17) is increased. Can be secured. Then, by securing a certain amount of this superscript resin, for example, an effect of absorbing the thickness of the copper foil 27 serving as an inner layer pattern in FIGS. 4A and 4B described later can be obtained.

  First, a woven fabric made of glass fibers 17 having a thickness of 15 microns was prepared. And as shown in FIG. 3, it sets to the installation 23, it sends to the direction shown by the arrow 21a, and the member 25 set to the tank 24 is impregnated. Then, the amount of impregnation of the member 25 is adjusted while turning the equipment 23 in the direction of the arrow 21b. Then, the solvent component is removed from the member 25 by flowing through a dryer or the like (not shown) as indicated by an arrow 21c. Further, the resin component contained in the member 25 is brought into a semi-cured state (state before main curing, so-called B-stage state) by heating or the like, and this is an impregnated semi-cured resin body containing the glass fiber 17 therein. Here, the semi-cured resin body comprises at least a semi-cured resin and an inorganic filler dispersed in the resin. In this way, the heat transfer prepreg 22 is continuously produced. In addition, the manufacturing method of the heat-transfer prepreg 22 is not limited to this.

  Next, the member 25 set in the tank 24 will be described. As the member 25, it is desirable to select a material having a thermal conductivity of 0.5 W / (m · K) or more and 20 W / (m · K) or less after the heat transfer prepreg 22 is cured. When the thermal conductivity after curing is less than 0.5 W / (m · K), the effect of heat transfer may be difficult to obtain. A material having a thermal conductivity exceeding 20 W / (m · K) is expensive and may be difficult to handle.

  Here, in order to realize 0.5 W / (m · K) or more and 20 W / (m · K) or less after curing, at least the member 25 is composed of a resin and an inorganic filler dispersed in the resin. Is desirable.

  And this resin was selected from epoxy resin, and inorganic filler was selected from alumina, aluminum nitride, boron nitride, silicon carbide, silicon nitride, silica, zinc oxide, titanium oxide, tin oxide, carbon, magnesium oxide, zircon silicate. It can be set as the inorganic filler which consists of at least 1 or more types.

  Furthermore, the resin may be a mixture of an epoxy resin and a rubber resin, or a mixture of an epoxy resin and a thermoplastic resin. Needless to say, a curing agent for curing the epoxy resin or the like is added as necessary.

  Also, by dissolving (or dispersing) these members 25 in a solvent (for example, methyl ethyl ketone, cyclopentanone, etc.), the coating property and workability can be improved. Then, the heat transfer prepreg 22 is obtained by making these members 25 dry and semi-cured.

  Next, how to produce a printed wiring board with high thermal conductivity using the heat transfer prepreg 22 will be described.

  4A and 4B are cross-sectional views illustrating an example of a method for fixing (or integrating) a copper foil on the surface of the heat transfer prepreg 22. 4A and 4B, 26 is a semi-cured resin body, 27 is a copper foil, and 28 is a press.

  First, as shown to FIG. 4 (A), the heat-transfer prepreg 22 is comprised from the glass fiber 17 and the semi-hardened resin body 26 which impregnates this. Then, the copper foil 27 is set on one surface or more of the heat transfer prepreg 22. Then, the press 28 is moved as indicated by the arrow 21, and the copper foil 27 is attached to one or more surfaces of the heat transfer prepreg 22. 4 (A) and 4 (B), a die set on the press 28 is not shown. And these sheet-like materials are pressure-integrated at a predetermined temperature. Thereafter, the press 28 is pulled away in the direction of the arrow 21 as shown in FIG. In this way, the copper foil 27 is fixed to one or more surfaces of the inner composite layer 12 to achieve higher heat transfer.

  The proportion of the semi-cured resin body 26 in the heat transfer prepreg 22 is preferably 30% by volume or more and 50% by volume or less of the entire heat transfer prepreg 22. If it is less than 30% by volume, the heat transfer property of the heat transfer prepreg 22 may be lowered. Further, if it is higher than 50% by volume, the flexibility of the heat transfer prepreg 22 may be affected.

  Next, the copper foil 27 fixed to one or more surfaces of the inner composite layer 12 is patterned into a predetermined shape. Note that patterning steps (photoresist application, exposure, development, copper foil 27 etching, photoresist removal step, etc.) are not shown (not shown).

  Next, how the core layer 18 is produced will be described with reference to FIGS.

  FIGS. 5A to 5D are schematic views illustrating a state in which the core layer 18 is manufactured in cross section. 5A to 5D, 29 is a hole.

  First, as shown in FIG. 5A, an inner composite layer 12 in which a copper foil 27 is processed into a predetermined pattern shape is prepared on at least one surface thereof. Then, the heat transfer prepreg 22 is set so as to sandwich the inner composite layer 12. Further, a copper foil 27 is set on the outside of the heat transfer prepreg 22. In addition, when using the commercially available copper foil 27, the adhesive force (for example, anchor effect and anchoring effect) of the copper foil 27 and the heat-transfer prepreg 22 can be improved by setting the rough surface side to the heat-transfer prepreg 22 side. . In this state, using a press device (not shown), these sheet-like materials are pressed, heated, and integrated. By heating at the time of pressing, the semi-cured resin body 26 included in the heat transfer prepreg 22 is softened, and the pattern of the copper foil 27 fixed on the heat transfer prepreg 22 (or the embedding of the step by the pattern), the copper The effect of increasing the adhesion with the foil 27 is obtained. Moreover, the effect which fixes the copper foil 27 is also acquired, without using an adhesive agent. In this way, the stacked body shown in FIG. 5B is formed.

  Next, the hole 29 is formed in the predetermined position of this laminated body, and it is set as the state of FIG.5 (C). In FIG. 5C, the hole 29 is formed by a drill, a laser or the like (both not shown).

  Thereafter, the inner wall of the hole 29 is plated with copper to obtain the state shown in FIG. As shown in FIG. 5D, interlayer connection between the copper foils 27 (or the surface layer wiring patterns 15) formed in different layers is performed by the via portions 13. Next, a core layer 18 is formed by forming a solder resist (not shown) or the like.

  Next, as shown in FIG. 6, the outer layer composite layer 11 and the surface layer wiring pattern 15 are formed on the surface of the core layer 18 to obtain the heat transfer printed wiring board 10. 6A to 6C are cross-sectional views illustrating an example of a method for manufacturing the heat transfer printed wiring board 10.

  As shown in FIG. 6A, the outer composite layer 11 is formed on the core portion 18. The outer composite layer 11 is an insulating heat transfer made of a resin and an inorganic filler. The outer composite layer 11 can be formed by applying a member 25 made of a resin and an inorganic filler dissolved in a solvent or the like to one or more surfaces of the core 18, drying, and curing. Alternatively, as shown in FIG. 3 (or using a resin film instead of the glass fiber 17 shown in FIG. 3 or using a coating device such as a doctor blade), a semi-cured resin and an inorganic material are formed on the resin film. The semi-cured resin body 26 made of a filler may be laminated as shown in FIG. 4 and then cured to form the outer composite layer 11.

  Here, the ratio of the resin in the outer composite layer 11 is preferably 60% by volume or more and 95% by volume or less of the entire outer composite layer 11. When the ratio of resin is less than 60 volume%, the heat conductivity in the outer-layer composite layer 11 part may fall. On the other hand, if it exceeds 95% by volume, the outer composite layer 11 becomes brittle and a part thereof may be chipped or cracked during mounting.

  Next, the hole 29 is formed in the outer composite layer 11 using a laser, a drill, or the like. The hole 29 may be formed only in the outer composite layer 11 as shown in FIG. 6B (or may be a so-called bottomed hole 29 that is not a through hole). By doing so, the diameter of the hole 29 can be reduced.

  It is desirable that the glass fiber 17 is not built in the outer composite layer 11. The glass fiber 17 may affect the heat transfer, the miniaturization of the holes 29 by laser or the like, and the heat transfer of the outer composite layer 11.

  Next, as shown in FIG. 6C, a copper film is formed on the surface of the outer composite layer 11 by a thin film method (evaporation method including sputtering), a plating method, or the like, thereby forming a surface wiring pattern 15. . Here, in the hole 29, the surface layer wiring pattern 15 and the internal electrode 14 are connected as the blind via 16.

  The outer composite layer 11 and the inner composite layer 12 are preferably composed of at least a resin and an inorganic filler. The reason why the inorganic filler is added is to increase the heat conductivity of the outer composite layer 11 and the inner composite layer 12.

  Further, the content of the inorganic filler in the outer composite layer 11 is desirably 60% by volume or more and 95% by volume or less. If it is less than 60% by volume, the heat transfer property in the outer composite layer 11 may be lowered. Moreover, when it exceeds 95 volume%, the moldability as the outer-layer composite layer 11 may be affected.

  The resin constituting the outer layer composite layer 11 and the inner layer composite layer 12 may be a thermoplastic resin or a thermosetting resin. Thus, the heat transfer printed wiring board 10 described with reference to FIG. In FIG. 1, FIG. 2, FIG. 6C, etc., the solder resist and the like are not shown.

  The outer composite layer 11 preferably has a thickness of 10 microns to 200 microns (desirably 100 microns or less). If the thickness of the outer composite layer 11 is less than 10 microns, pinholes may occur in the outer composite layer 11. Moreover, when the thickness exceeds 100 microns, there exists a possibility of affecting heat conductivity.

  The outer composite layer 11 may be a plurality of layers (desirably 2 or more and less than 5 layers. If 5 layers are exceeded, the cost may increase due to an increase in the number of man-hours). By forming the outer composite layer 11 into a plurality of layers, even when the outer composite layer 11 is thinned, pinholes are hardly generated. When the outer composite layer 11 has a plurality of layers, the thickness of the outer composite layer 11 per layer is desirably 5 microns or more. In the case of less than 5 microns, it is necessary to select a fine inorganic filler that is difficult to disperse by curing as the inorganic filler to be added.

  When the outer composite layer 11 has a plurality of layers, the composition of the outer composite layer 11 (content of resin or inorganic filler, etc.) is changed according to each layer (or optimized according to each layer). Thus, yield and characteristics can be improved.

(Embodiment 3)
Next, materials used for the heat transfer printed wiring board 10, the heat transfer prepreg 22, the outer composite layer 11, and the like will be described. As the resin used here, for example, an epoxy resin can be selected.

  And the epoxy resin, as the inorganic filler, at least selected from alumina, aluminum nitride, boron nitride, silicon carbide, silicon nitride, silica, zinc oxide, titanium oxide, tin oxide, carbon, magnesium oxide, zircon silicate, magnesium oxide It can be set as the inorganic filler which consists of 1 or more types.

  The average particle size of the inorganic filler is preferably in the range of 0.01 μm to 50 μm. Since the specific surface area increases as the average particle size becomes smaller, the heat radiation area increases and the radiation efficiency increases. However, when the average particle size becomes 0.01 μm or less, the specific surface area increases, and dispersion and kneading become difficult. On the other hand, when the thickness exceeds 50 μm, the outer composite layer 11 and the inner composite layer 12 become thick, which may affect the heat transfer properties of the heat transfer printed wiring board 10.

  In order to increase the filling rate of the inorganic filler, a plurality of types of inorganic fillers having different particle size distributions may be selected and used in combination.

  In addition, the heat conductivity in a resin part can be raised by making 60 to 100 weight% of epoxy resins into crystalline epoxy resin. When the proportion of the crystalline epoxy resin in the entire epoxy resin is less than 60% by weight, the effect of adding the crystalline epoxy resin may not be obtained. Moreover, heat conduction can be improved by making all of the epoxy resin (or 100% by weight) crystalline epoxy. Moreover, although the crystalline epoxy resin after hardening may be easily broken in some cases, it can be made difficult to break by adding a rubber resin or a thermoplastic resin. By adding these as fine particles, the influence on heat conduction can be suppressed.

  (Chemical Formula 1) is a structural diagram showing an example of a crystalline epoxy resin.

In (Chemical Formula 1), X in the structural diagram of the crystalline epoxy resin is S (sulfur) or O (oxygen), C (carbon), or none (short bond). R1, R2, R3, and R4 are CH ₃ , H, t-Bu, and the like. R1 to R4 may be the same.

  (Chemical Formula 2) is a structural diagram of a curing agent used for curing a crystalline epoxy resin.

  In the structural formula of (Chemical Formula 2), X is S (sulfur), O (oxygen) or a short bond. A polymer obtained by mixing the main component of (Chemical Formula 1) and the curing agent of (Chemical Formula 2) and polymerizing may be called a crystalline epoxy resin.

  The ratio between the main agent and the curing agent is calculated from the epoxy equivalent. A curing agent other than (Chemical Formula 2) may be used as the curing agent. In addition, as a crystalline epoxy resin, the thing of the structure of the following (Chemical Formula 3)-(Chemical Formula 8) can also be used.

  (Chemical Formula 3) to (Chemical Formula 8) are structural diagrams showing examples of crystalline epoxy resins. Such a crystalline epoxy resin has a melting point of about 50 to 121 ° C. and a low dissolution viscosity (for example, a viscosity at 150 ° C. of 6 to 20 mPa · s), so that it is easy to mix and disperse the inorganic filler. It is done. The degree of polymerization of these crystalline epoxy resins is suitably 20 or less (further 10 or less, desirably 5 or less). If the degree of polymerization is greater than 20, the molecule may be too large and difficult to crystallize.

  When a crystalline epoxy resin is used, both the thermal conductivity and the mechanical strength can be improved by using a thermoplastic resin having a phenyl group as the thermoplastic resin added here. Next, the effect of adding a thermoplastic resin having a phenyl group will be described.

  By adding a thermoplastic resin having the same phenyl group to a crystalline epoxy resin (preferably one having a phenyl group), the flexibility of the crystalline epoxy can be increased while maintaining the crystallinity of the crystalline epoxy. Here, as the thermoplastic resin having a phenyl group, a thermoplastic resin containing a phenyl group in the main chain such as PPE (polyphenylene ether), PPS (polyphenylene sulfide), PES (polyethersulfone), or the like can be used. Even if such a thermoplastic resin is added to the epoxy resin, it hardly affects the thermal conductivity. Moreover, the effect which raises the intensity | strength (for example, difficulty of a crack) of the completed heat-transfer printed wiring board 10 is acquired by adding such a thermoplastic resin.

(Embodiment 4)
As Embodiment 4, the result of measuring the bending strength of the heat transfer printed wiring board 10 described in Embodiments 1 to 3 is shown.

  FIG. 7 is a schematic diagram illustrating an example of a bending strength evaluation method. In FIG. 7, 30 is a jig. In FIG. 7, the heat transfer printed wiring board 10 is set between the jigs 30, and the heat transfer printed wiring board 10 is bent using the jig 30 in the direction indicated by the arrow 21. In the experiments by the inventors, the conventional product shown in FIGS. 8 to 9 was broken (broken) when bent by 1 to 2 mm. On the other hand, the heat transfer printed wiring board 10 of the present invention did not break even when bent by 4 to 5 mm. The sample size (heat transfer printed wiring board) is 40 mm × 4 mm × t2 mm.

  As described above, the thermal conductivity obtained by laminating the glass woven fabric, the inner composite layer 12 impregnating the glass woven fabric, and the internal electrode 14 in a single layer or more is 0.5 W / (m · K) or more. Provided is a heat transfer printed wiring board including a core layer 18 of 20 W / (m · K) or less, an outer composite layer formed on the core layer 18, and a surface wiring pattern 15 formed on the outer composite layer. This makes it possible to reduce the size and performance of various electronic devices.

  The thermal conductivity obtained by laminating a plurality of glass woven fabric, the inner composite layer 12 impregnated with the glass fabric, and the internal electrode 14 is 0.5 W / (m · K) or more and 20 W / (m · K) or less. On the core layer 18, the outer composite layer 11 formed on the core layer 18 and having a thermal conductivity of 3 W / (m · K) or more and 20 W / (m · K) or less, and on the outer layer composite layer 11 Provided is a heat transfer printed wiring board 10 comprising a formed surface layer wiring pattern 15 and a blind via 16 for connecting the internal electrode 14 and the surface layer wiring pattern 15 through a hole formed in the outer layer composite layer 11. This makes it possible to reduce the size and performance of various electronic devices.

  The proportion of the resin in the inner composite layer 12 is 30% by volume or more and 50% by volume or less of the entire inner layer composite layer 12, thereby reducing the size and improving the performance of various electronic devices. Is possible.

  The proportion of the resin in the outer composite layer 11 is 60% by volume or more and 95% by volume or less of the entire outer layer composite layer 11, thereby reducing the size and improving the performance of various electronic devices. Is possible.

  A heat transfer prepreg 22 having a heat conductivity after curing of 0.5 W / (m · K) or more and 20 W / (m · K) or less, the heat transfer prepreg 22 being a glass woven fabric or a non-woven fabric, The semi-cured resin body 26 impregnated with the glass woven fabric or the non-woven fabric. The semi-cured resin body 26 includes a heat transfer prepreg 22 composed of a semi-cured resin and an inorganic filler dispersed in the resin. By providing, the heat-transfer printed wiring board 10 which has high heat conductivity and is difficult to break even when bent can be manufactured.

  The semi-cured resin body 26 includes at least a semi-cured epoxy resin and alumina, aluminum nitride, boron nitride, silicon carbide, silicon nitride, silica, titanium oxide, tin oxide, carbon, magnesium oxide, zircon dispersed therein. By providing the heat transfer prepreg 22 composed of at least one kind of inorganic filler selected from silicates, the heat transfer printed wiring board 10 having high heat transfer and not easily cracked even when bent can be manufactured.

  Among the epoxy resins, 60 wt% or more and 100 wt% or less provide the heat transfer prepreg 22 that is a crystalline epoxy resin, thereby improving the heat transfer performance of the heat transfer printed wiring board 10 produced using the heat transfer prepreg 22. Enhanced.

  By providing the heat transfer prepreg 22 in which the degree of polymerization of the crystalline epoxy resin is 20 or less, the heat transfer property of the heat transfer printed wiring board 10 produced using the heat transfer prepreg 22 can be enhanced.

  A step of preparing a heat transfer body comprising at least a resin and an inorganic filler dispersed therein, wherein the thermal conductivity after thermosetting is 0.5 W / (m · K) or more and 20 W / (m · K) or less. And a step of impregnating the heat transfer body into a glass woven fabric or non-woven fabric, and then bringing the heat transfer body into a semi-cured state, by the method of manufacturing the heat transfer prepreg 22, the heat transfer prepreg 22 is stabilized. Manufacture is possible.

  A glass woven fabric or glass nonwoven fabric composed of glass fibers 17 and a composite layer having a thermal conductivity of 0.5 W / (m · K) or more and 20 W / (m · K) or less after being impregnated with the glass fiber 17; The step of laminating heat transfer prepreg 22 and copper foil to form a laminate, and the thermal conductivity after curing is 3 W / (m · K) or more and 20 W / (m · K) on the laminate. The outer layer composite layer 11 to be described below, the surface layer wiring pattern 15 formed on the outer layer composite layer 11, the copper foil to be the internal electrode 14 through the hole formed in the outer layer composite layer 11, and the surface layer wiring pattern 15 Since the heat transfer printed wiring board 10 can be stably manufactured by the method of manufacturing the heat transfer printed wiring board 10 including the step of forming the blind via 16 for connecting the mobile phone, the plasma television, Instrumentation products, compact equipment where heat dissipation for industry is required, the performance can be realized.

  As described above, depending on the heat transfer printed wiring board according to the present invention, the heat transfer prepreg used in the heat transfer printed wiring board and the method for manufacturing the same, and the method for manufacturing the heat transfer printed wiring board, the mobile phone, the plasma television, the electrical equipment, or the industry This makes it possible to reduce the size and performance of equipment that requires heat dissipation.

Sectional drawing of the heat-transfer printed wiring board in Embodiment 1 Cross-sectional view explaining heat transfer mechanism of heat transfer printed wiring board Sectional drawing explaining an example of the manufacturing method of the heat-transfer prepreg used for manufacture of a heat-transfer printed wiring board (A) (B) is sectional drawing explaining an example of the method of fixing (or integrating) copper foil on the surface of a heat-transfer prepreg. (A)-(D) are the schematic diagrams explaining a mode that a core layer is produced in a cross section. (A)-(C) are sectional drawings explaining an example of the manufacturing method of a heat-transfer printed wiring board. Schematic diagram showing an example of bending strength evaluation method (A) and (B) are cross-sectional views illustrating a state in which a crystalline polymer having a mesogenic group is oriented using a magnetic field to increase the thermal conductivity. Sectional drawing which shows an example of the conventional heat-transfer prepreg which improved the bendability

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Heat-transfer printed wiring board 11 Outer layer composite layer 12 Inner layer composite layer 13 Via part 14 Internal electrode 15 Surface layer wiring pattern 16 Blind via 17 Glass fiber 18 Core layer 19 Electronic component 20 Solder part 21 Arrow 22 Prepreg 23 Apparatus 24 Tank 25 Member 26 Semi-cured resin body 27 Copper foil 28 Press 29 Hole 30 Jig

Claims (11)

A glass fabric, an inner composite layer impregnating the glass fabric, and an internal electrode, each having a thermal conductivity of 0.5 W / (m · K) or more and 20 W / (m · K) or less, each laminated with a single layer or more. A core layer,
An outer composite layer formed on the core layer;
Surface layer wiring pattern formed on this outer composite layer,
Heat transfer printed wiring board consisting of A core layer having a thermal conductivity of 0.5 W / (m · K) or more and 20 W / (m · K) or less formed by laminating a plurality of glass woven fabrics, an inner composite layer impregnated therewith, and internal electrodes. When,
An outer composite layer having a thermal conductivity of 3 W / (m · K) or more and 20 W / (m · K) or less formed on the core layer;
Surface layer wiring pattern formed on this outer composite layer,
A blind via connecting the internal electrode and the surface wiring pattern through a hole formed in the outer composite layer;
Heat transfer printed wiring board consisting of 3. The heat transfer printed wiring board according to claim 1, wherein a ratio of the resin in the inner composite layer is 30% by volume or more and 50% by volume or less of the entire inner composite layer. The heat transfer printed wiring board according to claim 1, wherein a ratio of the resin in the outer composite layer is 60% by volume or more and 95% by volume or less of the entire outer composite layer. A heat transfer prepreg having a heat conductivity after curing of 0.5 W / (m · K) or more and 20 W / (m · K) or less, the heat transfer prepreg comprising a glass woven fabric or a nonwoven fabric and the glass It consists of a semi-cured resin body impregnated with woven or non-woven fabric,
This semi-cured resin body is a heat transfer prepreg composed of a semi-cured resin and an inorganic filler dispersed in the resin. The semi-cured resin body is at least a semi-cured epoxy resin,
An inorganic filler made of at least one selected from alumina, aluminum nitride, boron nitride, silicon carbide, silicon nitride, silica, titanium oxide, tin oxide, carbon, magnesium oxide, and zircon silicate dispersed therein; The heat transfer prepreg according to claim 5, comprising: The heat transfer prepreg according to claim 6, wherein 60 wt% or more and 100 wt% or less of the epoxy resin is a crystalline epoxy resin. The heat transfer prepreg according to claim 7, wherein the crystalline epoxy resin has the following structural formula.

The heat transfer prepreg according to any one of claims 7 and 8, wherein the degree of polymerization of the crystalline epoxy resin is 20 or less. A step of preparing a heat transfer body comprising at least a resin and an inorganic filler dispersed therein, wherein the thermal conductivity after thermosetting is 0.5 W / (m · K) or more and 20 W / (m · K) or less. When,
A step of impregnating the heat transfer body into a glass woven fabric or non-woven fabric and then setting the heat transfer body in a semi-cured state;
A method for producing a heat transfer prepreg having: A heat transfer prepreg comprising a glass woven fabric and a composite layer having a thermal conductivity of 0.5 W / (m · K) or more and 20 W / (m · K) or less after being impregnated with the glass woven fabric;
A step of laminating copper foil and forming a laminate;
An outer layer composite layer having a thermal conductivity of 3 W / (m · K) or more and 20 W / (m · K) or less on the laminate, and a surface layer wiring pattern formed on the outer layer composite layer; A step of forming a blind via for connecting the copper foil and the surface wiring pattern through a hole formed in the outer composite layer,
The manufacturing method of the heat-transfer printed wiring board which has.

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