JP5288949B2 - Pre-preg sheet, wiring board and mounting structure - Google Patents

Description

  The present invention relates to a prepreg sheet, a wiring board manufactured using the prepreg sheet, and a mounting structure in which an electronic component is mounted on the wiring board. Such a mounting structure is used for an electronic device. Such electronic devices are various audio-visual devices, home appliances, communication devices, computer devices or peripheral devices thereof.

  Conventionally, wiring boards on which electronic components are mounted are known. Such electronic components are semiconductor elements or capacitors. Such a semiconductor element is an IC (Integrated Circuit) or an LSI (Large Scale Integration).

  Such a wiring board is known to include a base formed by laminating prepreg sheets, and a conductive layer formed on the upper surface or the lower surface of the base.

  Patent Document 1 describes such a prepreg sheet having a configuration including an elongated single fiber and a resin portion precursor that covers the single fiber. Such a resin part precursor constitutes a resin part on the wiring board.

However, the linear expansion coefficient of the single fiber and the linear expansion coefficient of the resin portion are different. Therefore, for example, when the prepreg sheet of Patent Document 1 is applied to a wiring board, heat is applied to the wiring board due to heating at the time of solder reflow performed when the electronic component is mounted on the wiring board or heat generation of the electronic component. In this case, a difference in thermal expansion occurs between the single fiber and the resin portion. As a result, a strong thermal stress is applied to the boundary between the single fiber and the resin portion, the single fiber and the resin portion are peeled off, and the reliability of the wiring board is likely to be lowered.
JP-A-2005-29912

  The present invention provides a prepreg sheet, a wiring board, and a mounting structure that meet the demand for increasing the adhesive strength between a single fiber and a resin portion.

A prepreg sheet according to an embodiment of the present invention includes an elongated single fiber and a resin portion precursor that covers the single fiber, and the single fiber has a plurality of groove-shaped recesses along a longitudinal direction thereof. The plurality of recesses are characterized in that the resin part precursor is in contact with the inner surface, and the bottom part has a settling part and a raised part arranged along the longitudinal direction .

A wiring board according to an embodiment of the present invention includes a base having an elongated single fiber, a resin portion that covers the single fiber, and a conductive layer formed on an upper surface or a lower surface of the base, The single fiber has a plurality of groove-shaped concave portions along the longitudinal direction on the surface, and the plurality of concave portions are arranged along the longitudinal direction at the bottom while the resin portion is in contact with the inner surface. It has a settling portion and a raised portion .

  According to the prepreg sheet, the wiring board, and the mounting structure according to one embodiment of the present invention, the adhesive strength between the single fiber and the resin portion can be increased. As a result, a highly reliable wiring board and mounting structure can be obtained.

  Below, the prepreg sheet concerning 1st Embodiment of this invention is demonstrated in detail based on FIGS. 1-3.

  A prepreg sheet 1 shown in FIGS. 1 and 2 includes a plurality of elongated single fibers 2 and a resin portion precursor 3 a that covers the single fibers 2.

  The plurality of single fibers 2 are arranged in a sheet shape in one direction in the prepreg sheet 1, and each has a thread-like structure. As a result, the flatness of the upper and lower surfaces of the prepreg sheet 1 can be improved. The single fiber 2 includes, for example, a low thermal expansion resin, a low thermal expansion glass fiber, or the like, and preferably includes a low thermal expansion resin. As the low thermal expansion resin, for example, polyparaphenylene benzbisoxazole resin, wholly aromatic polyamide resin or wholly aromatic polyester resin may be used. As the low thermal expansion glass fiber, S glass or T glass may be used.

  The single fiber 2 is preferably made of a material having a low linear expansion coefficient. The linear expansion coefficient in the longitudinal direction (X direction) of the single fiber 2 is desirably set to −12 ppm / ° C. or more and 5 ppm / ° C. or less. The linear expansion coefficient in the cross-sectional direction (XZ plane direction) orthogonal to the longitudinal direction of the single fiber 2 is preferably set to 50 ppm / ° C. or more and 110 ppm / ° C. or less. The linear expansion coefficient is measured by a test method according to ISO11359-2: 1999.

  The resin portion precursor 3a is filled between the single fibers 2 and is formed so as to cover the upper and lower surfaces of the single fibers 2 arranged in one direction. The resin part precursor 3a includes an uncured thermosetting resin or the like. Thermosetting resins include epoxy resins, bismaleimide triazine resins, cyanate resins, polyimide resins or polyphenyl ether resins. The linear expansion coefficient of the thermosetting resin is desirably set to, for example, 10 ppm / ° C. or more and 50 ppm / ° C. or less. Uncured means an A-stage or B-stage according to ISO 472: 1999.

  Next, the single fiber 2 will be described in more detail.

  As shown in FIGS. 3A to 3E, the single fiber 2 has a plurality of groove-like recesses C1 along the longitudinal direction on the surface, and the resin portion precursor 3a is in contact with the inner surface of the recess C1. The plurality of recesses C1 are arranged along the circumferential direction of the cross section orthogonal to the longitudinal direction. Thereby, while the surface area of the single fiber 2 increases, a part of resin part precursor 3a can be easily filled in the recessed part C1. As a result, since the contact area between the single fiber 2 and the resin part precursor 3a increases, the adhesive strength between the single fiber 2 and the resin part precursor 3a can be increased. In addition, the recessed part C1 may be single.

  The inner surface of the recess C1 is preferably a curved surface. As a result, when stress is applied in the longitudinal direction of the single fiber 2, it is possible to suppress stress concentration on a part of the inner surface of the recess C <b> 1 and to increase the mechanical strength of the single fiber 2.

  The cross-sectional area perpendicular to the longitudinal direction of the single fiber 2 is preferably set to 27 μm 2 or more and 192 μm 2 or less, for example. Further, it is desirable that the depth of the recess C1 is set to, for example, 1 μm or more and 5 μm or less. When the depth of the concave portion C1 is 1 μm or more, a part of the resin portion precursor 3a is easily filled in the concave portion C1. Moreover, the contact area of the single fiber 2 and the resin part precursor 3a can be increased, maintaining the mechanical strength of the single fiber 2 because the depth of the recessed part C1 is 5 micrometers or less. In addition, the depth of the recessed part C1 means the distance from the opening of the recessed part C1 to the bottom part of the recessed part C1. In addition, the width of the recess C1 is desirably set to, for example, 1 μm or more and 3 μm or less. When the width of the recess C1 is 1 μm or more, a part of the resin portion precursor 3a is easily filled in the recess C1. Moreover, the contact area of the single fiber 2 and the resin part precursor 3a can be increased, maintaining the mechanical strength of the single fiber 2 because the width | variety of the recessed part C1 is 3 micrometers or less. In addition, the width | variety of the recessed part C1 means the width to the said circumference direction in opening of the recessed part C1. Moreover, it is desirable that the single fiber 2 has 3 to 12 groove-shaped recesses C1. Further, it is desirable that the distance between the bottoms of the adjacent recesses C1 is set to 1 μm or more and 8 μm or less.

  As shown in FIG. 2C, the adjacent single fibers 2 correspond to the groove-shaped recess C <b> 1 of one single fiber 2 and the region between the adjacent groove-shaped recesses C <b> 1 of the other single fiber 2. It is desirable that they are arranged. As a result, the adjacent single fibers 2 can be arranged closer to each other, and the density of the single fibers 2 can be increased in the prepreg sheet 1. Thereby, the improvement of the rigidity of the wiring board 5 formed by hardening the prepreg sheet 1 and the reduction of a thermal expansion coefficient become easy. Further, the adjacent single fibers 2 have an anchor effect due to the groove-shaped recess C1 of one single fiber 2 and the region between adjacent groove-shaped recesses C1 of the other single fiber 2, The adhesive strength between the single fiber 2 and the resin part precursor 3a positioned between the adjacent single fibers 2 can be increased. Moreover, since the adjacent single fibers 2 have an anchor effect, the positional deviation of the single fibers 2 caused by the separation between the single fibers 2 and the resin portion precursor 3a can be reduced.

  Next, a mounting structure including the wiring board according to the first embodiment of the present invention will be described with reference to FIG. In addition, the wiring board of this embodiment is produced using the prepreg sheet mentioned above.

  The mounting structure 4 shown in FIG. 4 includes a wiring board 5 and an electronic component 7 that is flip-chip mounted on the upper surface of the wiring board 5 via bumps 6.

  The wiring board 5 includes a base 8, a plurality of insulating layers 9 stacked on the top and bottom surfaces of the base 8, and a plurality of conductive layers 10 disposed on the top and bottom surfaces of the insulating layer 9. Yes.

  The base 8 has a structure in which a plurality of fiber layers 11 are laminated. The fiber layer 11 is formed by the prepreg sheet 1 described above. The fiber layer 11 includes a plurality of elongated single fibers 2 and a resin portion 3 b that covers the single fibers 2.

  The single fibers 2 correspond to the single fibers 2 included in the prepreg sheet 1 described above, and are arranged in a sheet shape in one direction. The single fiber 2 is preferably made of a material having a low linear expansion coefficient. By using such a single fiber 2, the difference in coefficient of linear expansion between the wiring substrate 5 and the electronic component 7 is reduced, and when heat is applied to the mounting structure 4, the wiring substrate 5 and the electronic component 7 are not affected. Thermal stress applied between them can be reduced.

  It is desirable that adjacent fiber layers 11 are orthogonal to each other in the longitudinal direction of each single fiber 2. As a result, the difference between the linear expansion coefficients in two orthogonal directions (X direction and Y direction) is reduced on the plane (XY plane) of the wiring board 5, so that the linear expansion coefficient between the wiring board 5 and the electronic component 7 is reduced. The difference is reduced.

  The resin part 3b corresponds to the resin part precursor 3a included in the prepreg sheet 1 described above, and is formed by curing an uncured thermosetting resin contained in the resin part precursor 3a described above. The

  The resin portion 3b is in contact with the inner surface of the recess C1. As a result, since the contact area between the single fiber 2 and the resin portion 3b increases, the adhesive strength between the single fiber 2 and the resin portion 3b can be increased. Thereby, possibility that a crack will arise in base 8 can be reduced, and reliability of wiring board 5 can be improved.

  The base 8 is formed with a plurality of through holes S penetrating in the vertical direction (Z direction). A through-hole conductor 12 is formed on the inner wall of the through-hole S. The plurality of through-hole conductors 12 electrically connect the conductive layers 10 formed on the upper surface and the lower surface of the base 8. The through-hole conductor 12 is made of a conductive material. The conductive material includes, for example, copper, silver, nickel, chromium, or the like. In the present embodiment, the through-hole conductor 12 is formed in a cylindrical shape, and in order to ensure the flatness of the base body 8, the insulator 13 is filled in the cylindrical shape. The insulator 13 includes a resin material, a filler, an elastomer, a flame retardant, a curing agent, and the like. For example, an epoxy resin or a cyanate resin may be used as the resin material. Further, as the filler, for example, silicon oxide or aluminum oxide may be used. Further, as the elastomer, a styrene elastomer or a polyester elastomer may be used.

  Moreover, although the space | gap produced between the single fiber 2 and the resin part 3b may be exposed in the inner wall of the through hole S, in this embodiment, the single fiber 2 and the resin part 3b are firmly established. It is glued. Therefore, since the separation between the single fiber 2 and the resin portion 3b is suppressed, the possibility that voids are generated in the base body 8 due to the separation between the single fiber 2 and the resin portion 3b can be reduced. For this reason, the possibility that the conductive material constituting the through-hole conductor 12 dissolves in moisture in the atmosphere and enters the gap, reaches the adjacent through-hole conductor 12, and short-circuits the through-hole conductors 12 to each other is reduced. it can. Thereby, the electrical reliability of the wiring board 5 can be improved.

  The insulating layer 9 has an adhesive layer 9a and a resin layer 9b.

  The adhesive layer 9a is for firmly bonding the resin layers 9b or the resin layer 9b and the substrate 8 and includes a thermosetting resin or a thermoplastic resin. As the thermosetting resin, for example, a polyimide resin, an acrylic resin, an epoxy resin, a urethane resin, a cyanate resin, a silicon resin, or a bismaleimide triazine resin may be used. As the thermoplastic resin, since it is necessary to have heat resistance that can withstand heating during solder reflow, the softening temperature of the constituent material is preferably 200 ° C. or higher, and for example, a liquid crystal polymer is preferably used. The linear expansion coefficient of the adhesive layer 9a is preferably set to, for example, 15 ppm / ° C. or more and 80 ppm / ° C. or less. Moreover, it is desirable that the adhesive layer 9a is set to have a thickness of, for example, 2 μm or more and 20 μm or less.

  The resin layer 9b is for improving the mechanical strength of the wiring board 5, and does not include a base material, and preferably contains a thermosetting resin or a thermoplastic resin. As the thermosetting resin or thermoplastic resin, it is desirable to use a material that is elastically deformable and has excellent heat resistance and hardness. As the thermosetting resin having such characteristics, for example, polyimide benzoxazole resin, polyparaphenylene benzbisoxazole resin, wholly aromatic polyamide resin, or wholly aromatic polyester resin may be used. Moreover, as a thermoplastic resin, you may use a thermoplastic polyimide resin or a liquid crystal polymer resin, for example. Among the above materials, it is desirable to use polyimide benzoxazole resin or polyparaphenylene benzbisoxazole resin. The polyparaphenylene benzbisoxazole resin has a low linear expansion coefficient of −5 ppm / ° C. to 5 ppm / ° C. By using such a low thermal expansion resin, the difference in thermal expansion between the wiring board 5 and the electronic component 7 can be reduced, and the thermal stress between the wiring board 5 and the electronic component 7 can be reduced. The thickness of the resin layer 9b is desirably set to be 2 μm or more and 20 μm or less, for example.

  A via hole V is formed in the insulating layer 9, and a via conductor 14 is formed in the via hole V. The via conductors 14 electrically connect the conductive layers 10 disposed on the upper and lower surfaces of the insulating layer 9. Further, the via conductor 14 has a cross-sectional area in the plane direction of the wiring board 5 that increases, for example, from the upper surface of the substrate 8 toward the upper surface of the wiring substrate 5 or from the lower surface of the substrate 8 toward the lower surface of the wiring substrate 5. It is formed as follows. The via conductor 14 is made of a conductive material. The conductive material includes, for example, copper, silver, gold, aluminum, nickel, or chromium. The linear expansion coefficient of the via conductor 14 is desirably set to, for example, 12 ppm / ° C. or more and 20 ppm / ° C. or less.

  The conductive layer 10 includes a signal layer that transmits an electrical signal and a ground layer that is connected to the electronic component 7. The conductive layer 10 is formed on the upper and lower surfaces of the base 8 and is electrically connected to the through-hole conductor 12. The conductive layer 10 is formed on the upper and lower surfaces of the insulating layer 9 and is electrically connected to the via conductor 14. Note that the conductive layer 10 is formed of a conductive material. The conductive material includes, for example, copper, silver, gold, nickel, chromium, titanium, molybdenum, tungsten, zirconium, or an alloy thereof. Moreover, it is desirable that the linear expansion coefficient of the conductive layer 10 is set to, for example, 12 ppm / ° C. or more and 20 ppm / ° C. or less.

  The electronic component 7 is electrically connected to the conductive layer 10 via the bump 6. A conductive material is used for the material of the bump 6. The conductive material includes, for example, copper, silver, zinc, tin, indium, bismuth or antimony. As the electronic component 7, a semiconductor element or a capacitor may be used. For example, an IC or LSI may be used as the semiconductor element. As a material of the semiconductor element, silicon, germanium, gallium arsenide, gallium arsenide phosphorus, gallium nitride, silicon carbide, or the like may be used. The thickness of the electronic component 7 is preferably 0.1 mm to 1 mm, for example.

  Next, a method for manufacturing the mounting structure 4 including the above-described wiring board 5 using the above-described prepreg sheet 1 will be described with reference to FIGS.

  First, the prepreg sheet 1 described above is prepared.

  (1) As shown in FIGS. 5A and 5B, an elongated single fiber 2 is prepared.

  (2) As shown in FIGS. 5C and 5D, a groove-shaped recess C <b> 1 is formed in the single fiber 2 by pressing a part of the side surface of the single fiber 2. Specifically, for example, a part of the side surface of the single fiber 2 is pressed as follows. First, as shown in FIGS. 6A to 6C, two rollers 15 a each having a hollow portion D on the outer periphery 15 ax and having the hollow portion D formed along the circumferential direction are prepared. The surface which forms the hollow part D of outer periphery 15ax has the unevenness | corrugation arranged along the width direction, and this unevenness | corrugation is formed so that it may extend | stretch along the circumference direction of outer periphery 15ax. Next, as shown in FIGS. 7A to 8, the two rollers 15 a are brought into contact with each other so that the respective recessed portions D are combined, and the two recessed portions D correspond to the cross-sectional shape of the single fiber 2. A hole H is formed. And the single fiber 2 is moved to a longitudinal direction by making the single fiber 2 contact | abut to each roller 15a in the hole H, and rotating each roller 15a. As a result, a part of the outer periphery 15ax constituting the hollow part D presses a part of the side surface of the single fiber 2, and a groove-like recess C1 can be formed in the single fiber 2. Thus, since the recessed part C1 is formed by pressing a part of the side surface of the single fiber 2, the recessed part C1 can be formed while reducing the possibility that the molecules constituting the single fiber 2 are damaged. As a result, the concave portion C1 can be formed while maintaining the mechanical strength of the single fiber 2. The hole H may be formed by using three or more rollers 15a.

  Moreover, since the recessed part C1 is formed by pressing a part of side surface of the single fiber 2, the density of a part of the single fiber 2 constituting the recessed part C1 is higher than that of other parts of the single fiber 2. As a result, the hardness of a part of the single fiber 2 constituting the recess C1 is higher than that of other parts of the single fiber 2, so that the recess C1 is formed while maintaining the mechanical strength of the single fiber 2. be able to. The hardness of a part of the single fiber 2 can be measured by, for example, a microindentation method or a nanoindentation method. In the microindentation and nanoindentation methods, the area of the indentation that occurs when a fine indenter is pressed against the single fiber 2 is measured, and the pressing weight per unit area is obtained from the weight of pressing the indenter and the area of the indentation. This is a method for measuring hardness.

  Moreover, since the longitudinal direction of the single fiber 2 is parallel to the extending direction of the molecular chain of the single fiber 2, the single fiber 2 is pressed along the extending direction of the molecular chain. For this reason, the molecular chain of the single fiber 2 is disturbed in a wave shape and the possibility of being cut is reduced. As a result, fraying of the single fiber 2 can be reduced, and the concave portion C1 can be formed while maintaining the mechanical strength of the single fiber 2.

  When partially pressing the single fiber 2, it is desirable to press the single fiber 2 while heating it. Since the hardness of the single fiber 2 is reduced by heating, damage to the single fiber 2 due to pressing can be reduced, and the concave portion C1 can be easily formed in the single fiber 2. Moreover, when the single fiber 2 contains a low thermal expansion resin, since the hardness of the single fiber 2 is easily lowered by heating, the concave portion C1 can be easily formed in the single fiber 2.

  (3) As shown in FIGS. 9A and 9B, the single fibers 2 are arranged in one direction and spread, thereby forming the single fiber sheet 16. Here, when arranging the single fibers 2 in one direction, it is desirable to arrange them while applying vibration to the single fibers 2. Thereby, adjacent single fibers 2 are such that the region between the groove-shaped recess C1 of one single fiber 2 and the adjacent groove-shaped recess C1 of the other single fiber 2 correspond to each other. Can be arranged. As a result, since the anchor effect is exerted between the adjacent single fibers 2, the positional deviation of the single fibers 2 in the single fiber sheet 16 can be reduced. In addition, after arranging the single fiber 2 in one direction, by giving vibration to the single fiber 2, the adjacent single fibers 2 are separated from each other into a groove-like recess C <b> 1 of one single fiber 2 and the other single fiber 2. You may arrange so that the area | region between adjacent groove-shaped recessed parts C1 may correspond.

  (4) As shown in FIG. 9C to FIG. 9D, the single fiber sheet 16 is impregnated with the resin portion precursor 3 a, and the resin portion precursor 3 a is brought into contact with the inner surface of the concave portion C 1 of the single fiber 2. In this way, the prepreg sheet 1 can be produced.

  Next, using the prepreg sheet 1 described above, the mounting structure 4 including the wiring substrate 5 described above is manufactured.

  (5) As shown in FIGS. 10A and 10B, a plurality of prepreg sheets 1 are stacked and heated and pressurized. The plurality of prepreg sheets 1 are desirably laminated so that the longitudinal directions of the single fibers 2 between the adjacent prepreg sheets 1 are orthogonal to each other. The heating and pressurization is performed using, for example, a heating press machine. The temperature for heating the laminate of the prepreg sheet 1 is preferably set to be equal to or higher than the curing start temperature of the thermosetting resin contained in the resin portion precursor 3a and lower than the thermal decomposition temperature of the thermosetting resin. As a result, since the uncured thermosetting resin contained in the resin portion precursor 3a is cured, the stacked prepreg sheets 1 can be bonded to each other. As described above, the substrate 8 can be manufactured.

  Here, when the thermosetting resin is cured, the resin portion precursor 3 a becomes the resin portion 3 b and the prepreg sheet 1 becomes the fiber layer 11. The thickness of the base 8 is preferably set to, for example, 0.3 mm or more and 1.5 mm or less. The thermal decomposition temperature means a temperature at which the mass of the resin is reduced by 5% in thermogravimetry according to ISO11358: 1997.

  (6) As shown in FIG. 11A, a through hole S penetrating in the vertical direction is formed in the base 8. The through hole S is formed by, for example, drilling or laser processing. Further, it is desirable that several through holes S are formed. Further, it is desirable that the width of the through hole S is set to, for example, 0.1 mm or more and 1 mm or less.

  (7) As shown in FIG. 11B, a conductive material is deposited on the surface of the base 8 to form a conductive material layer 17. The conductive material layer 17 forms a cylindrical through-hole conductor 12 on the inner wall surface of the through-hole S. The conductive material layer 17 is formed by, for example, an electroless plating method.

  Here, when the possibility that the single fiber 2 and the resin portion 3a are peeled is reduced, when the through-hole conductor 12 is formed, the conductive material is formed in the gap generated by the separation of the single fiber 2 and the resin portion 3a. Can be prevented from entering. As a result, the possibility that such a conductive material short-circuits the through-hole conductors 12 can be reduced.

  (8) As shown in FIG. 12A, the inside of the cylindrical through-hole conductor 12 is filled with a resin material or the like to form the insulator 13.

  (9) As shown in FIG. 12B, a conductive material is deposited on the exposed portion of the insulator 13 to form a conductive material layer 17 on the exposed portion of the insulator 13. Such a conductive material is deposited by, for example, electroless plating, vapor deposition, CVD, or sputtering.

  (10) As shown in FIG. 13A, the conductive material layer 17 is patterned to form the conductive layer 10. The patterning of the conductive material layer 17 is performed using a conventionally well-known photolithography technique or the like.

  (11) As shown in FIGS. 13B and 14A, a resin layer 9b is bonded onto the conductive layer 10 via an adhesive layer 9a. Bonding is performed by heating and pressing. Heating and pressing are performed using, for example, a heating press. As described above, the insulating layer 9 composed of the adhesive layer 9a and the resin layer 9b can be formed.

  (12) As shown in FIG. 14B, a via hole V is formed in the insulating layer 9, and at least a part of the conductive layer 10 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 is formed by irradiating the upper surface of the resin layer 9b with laser light from the vertical direction. The via hole V can be formed such that the opening width becomes narrower from the upper surface of the resin layer 9 b toward the upper surface of the base 8 by adjusting the output of the laser beam.

  (13) As shown in FIG. 15A, the via conductor 14 is formed in the via hole V, and the conductive layer 10 is formed on the upper surface of the insulating layer 9. The via conductor 14 and the conductive layer 10 are formed by a well-known semi-additive method, subtractive method, full-additive method, or the like, and it is desirable that the via conductor 14 and the conductive layer 10 be formed by a semi-additive method. The wiring board 5 can be manufactured as described above.

  In addition, by repeating the steps (11) to (13), the multilayer wiring substrate 5 can also be manufactured.

  (14) As shown in FIG. 15B, the mounting structure 4 can be produced by flip-chip mounting the electronic component 7 on the wiring board 5 via the bumps 6.

  Next, a prepreg sheet including single fibers according to the second embodiment of the present invention will be described in detail with reference to FIG. In addition, description is abbreviate | omitted regarding the structure similar to 1st Embodiment mentioned above.

  As shown in FIGS. 16A to 16D, the single fiber 2 has a plurality of groove-like recesses C2 along the longitudinal direction on the side surface, and the recesses C2 are settled along the longitudinal direction at the bottom. It has a part 2v and a raised part 2w. The resin part precursor 3a is in contact with the inner surface of the recess C2. For this reason, while the surface area of the single fiber 2 increases, there exists an anchor effect in the said longitudinal direction and the said circumference direction. As a result, the adhesive strength between the single fiber 2 and the resin portion precursor 3a can be increased. In addition, the recessed part C1 may be single.

  The cross-sectional area perpendicular to the longitudinal direction of the single fiber 2 is preferably set to 27 μm or more and 192 μm or less, for example. Moreover, it is desirable that the depth of the settled portion v of the recess C2 is set to, for example, 1 μm or more and 5 μm or less. In addition, the depth of the raised portion w of the recess C2 is desirably set to, for example, 1 μm or more and 5 μm or less. The difference in depth between the sinking portion v of the recess C2 and the raised portion w of the recess C2 is preferably set to, for example, 1 μm or more and 3 μm or less.

  The plurality of recesses C2 include a first recess C2a and a second recess C2b, and the sinking portion 2v of the first recess C2a and the raised portion 2w of the second recess C2b correspond in the circumferential direction. It is desirable. As a result, since the cross section perpendicular to the longitudinal direction of the single fiber 2 has the settled portion v and the raised portion w on its outer periphery, the minimum value of the cross sectional area perpendicular to the longitudinal direction of the single fiber 2 increases, and the single fiber The mechanical strength of 2 can be increased. Moreover, it is desirable that the first recesses C2a and the second recesses C2b are alternately arranged along the circumferential direction.

  The present invention is not limited to the above-described embodiments, and various changes and improvements can be made without departing from the scope of the present invention. For example, in the above-described embodiment of the present invention, the configuration in which the electronic component 7 is flip-chip mounted on the upper surface of the wiring substrate 5 has been described, but the electronic component 7 may be mounted on the upper surface of the wiring substrate 5 by wire bonding.

1 is a perspective view of a prepreg sheet according to a first embodiment of the present invention. 2A is a cross-sectional view in the thickness direction of the prepreg sheet shown in FIG. 1, and FIG. 2B is a cross-sectional view in the thickness direction of the prepreg sheet shown in FIG. 1 orthogonal to the cross section shown in FIG. 2C is an enlarged view of a Y1 portion of the single fiber shown in FIG. 2B. 3A is a perspective view of a single fiber according to the first embodiment of the present invention, FIG. 3B is an enlarged view of a Y2 portion of the single fiber shown in FIG. 3A, and FIG. 3C is a single fiber shown in FIG. 3B. 3D is a cross-sectional view taken along line X1-X1 of the single fiber shown in FIG. 3C, and FIG. 3E is a cross-sectional view taken along line X2-X2 of the single fiber shown in FIG. 3C. It is. It is sectional drawing to the thickness direction of the mounting structure concerning 1st Embodiment of this invention. 5A is a perspective view for explaining a manufacturing process of the mounting structure shown in FIG. 4, FIG. 5B is an enlarged view of a Y3 portion explaining a manufacturing process of the mounting structure shown in FIG. 5A, and FIG. FIG. 5D is a perspective view illustrating a manufacturing process of the mounting structure shown in FIG. 5, and FIG. 5D is an enlarged view of a Y4 portion illustrating the manufacturing process of the mounting structure shown in FIG. 5C. 6A is a perspective view illustrating a manufacturing process of the mounting structure shown in FIG. 4, and FIG. 6B is an enlarged plan view of a Y5 portion illustrating a manufacturing process of the mounting structure shown in FIG. 6A. 6C is a cross-sectional view taken along line X3-X3 for describing a manufacturing process of the mounting structure shown in FIG. 6B. 7A is a perspective view for explaining a manufacturing process of the mounting structure shown in FIG. 4, and FIG. 7B is a plan view perpendicular to the rotation axis of the roller for explaining the manufacturing process of the mounting structure shown in FIG. 7A. is there. FIG. 8 is a cross-sectional view taken along line X4-X4 of an enlarged view of a Y6 portion for explaining a manufacturing process of the mounting structure shown in FIG. 7B. 9A is a cross-sectional view in the thickness direction illustrating the manufacturing process of the mounting structure shown in FIG. 4, and FIG. 9B is a cross-sectional view in the thickness direction illustrating the manufacturing process of the mounting structure shown in FIG. 9A. It is sectional drawing orthogonal to the cross section shown in FIG. 9C is a cross-sectional view in the thickness direction illustrating a manufacturing process of the mounting structure shown in FIG. 4, and FIG. 9D is a cross-sectional view in the thickness direction illustrating the manufacturing process of the mounting structure shown in FIG. 9C. It is sectional drawing orthogonal to the cross section shown in FIG. 10A and 10B are cross-sectional views illustrating a manufacturing process of the mounting structure shown in FIG. 11A and 11B are cross-sectional views illustrating a manufacturing process of the mounting structure shown in FIG. 12A and 12B are cross-sectional views illustrating a manufacturing process of the mounting structure shown in FIG. 13A and 13B are cross-sectional views illustrating a manufacturing process of the mounting structure shown in FIG. 14A and 14B are cross-sectional views illustrating a manufacturing process of the mounting structure shown in FIG. 15A and 15B are cross-sectional views illustrating a manufacturing process of the mounting structure shown in FIG. 16A is an enlarged perspective view of a single fiber according to a second embodiment of the present invention, FIG. 16B is a cross-sectional view orthogonal to the longitudinal direction of the single fiber shown in FIG. 16A, and FIG. It is sectional drawing in the X5-X5 line of the single fiber shown, FIG. 16D is sectional drawing in the X6-X6 line of the single fiber shown to FIG. 16B.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Prepreg sheet 2 Single fiber 3a Resin part precursor 3b Resin part 4 Mounting structure 5 Wiring board 6 Bump 7 Electronic component 8 Base
DESCRIPTION OF SYMBOLS 9 Insulating layer 9a Adhesive layer 9b Resin layer 10 Conductive layer 11 Fiber layer 12 Through-hole conductor 13 Insulator 14 Via conductor 15a Roller 15ax Outer periphery 16 Monofilament sheet 17 Conductive material layer C1 Recess S Through hole V Via hole D Recessed part H Hole Part

Claims (3)

An elongated monofilament,
A resin part precursor for coating the single fiber;
With
The monofilament has a plurality of groove-shaped recesses along its longitudinal direction on the surface,
The plurality of concave portions have a settling portion and a raised portion arranged in the longitudinal direction at the bottom while the resin portion precursor is in contact with the inner surface. A substrate having an elongated single fiber, and a resin portion covering the single fiber;
A conductive layer formed on the upper or lower surface of the substrate;
With
The monofilament has a plurality of groove-shaped recesses along its longitudinal direction on the surface,
The plurality of recesses have a settling portion and a raised portion arranged in the longitudinal direction at the bottom while the resin portion is in contact with the inner surface. The wiring board according to claim 2 ;
An electronic component mounted on the upper surface of the wiring board and electrically connected to the conductive layer;
The mounting structure characterized by comprising.

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