WO2013099205A1 - フレキシブル配線基板とその製造方法と、これを用いた実装製品と、フレキシブル多層配線基板 - Google Patents
フレキシブル配線基板とその製造方法と、これを用いた実装製品と、フレキシブル多層配線基板 Download PDFInfo
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- WO2013099205A1 WO2013099205A1 PCT/JP2012/008235 JP2012008235W WO2013099205A1 WO 2013099205 A1 WO2013099205 A1 WO 2013099205A1 JP 2012008235 W JP2012008235 W JP 2012008235W WO 2013099205 A1 WO2013099205 A1 WO 2013099205A1
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/0271—Arrangements for reducing stress or warp in rigid printed circuit boards, e.g. caused by loads, vibrations or differences in thermal expansion
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/40—Forming printed elements for providing electric connections to or between printed circuits
- H05K3/4038—Through-connections; Vertical interconnect access [VIA] connections
- H05K3/4053—Through-connections; Vertical interconnect access [VIA] connections by thick-film techniques
- H05K3/4069—Through-connections; Vertical interconnect access [VIA] connections by thick-film techniques for via connections in organic insulating substrates
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/40—Forming printed elements for providing electric connections to or between printed circuits
- H05K3/4038—Through-connections; Vertical interconnect access [VIA] connections
- H05K3/4046—Through-connections; Vertical interconnect access [VIA] connections using auxiliary conductive elements, e.g. metallic spheres, eyelets, pieces of wire
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/03—Use of materials for the substrate
- H05K1/0313—Organic insulating material
- H05K1/0353—Organic insulating material consisting of two or more materials, e.g. two or more polymers, polymer + filler, + reinforcement
- H05K1/036—Multilayers with layers of different types
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/03—Use of materials for the substrate
- H05K1/0313—Organic insulating material
- H05K1/0353—Organic insulating material consisting of two or more materials, e.g. two or more polymers, polymer + filler, + reinforcement
- H05K1/0366—Organic insulating material consisting of two or more materials, e.g. two or more polymers, polymer + filler, + reinforcement reinforced, e.g. by fibres, fabrics
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/03—Use of materials for the substrate
- H05K1/0393—Flexible materials
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
- H05K2201/01—Dielectrics
- H05K2201/0104—Properties and characteristics in general
- H05K2201/0129—Thermoplastic polymer, e.g. auto-adhesive layer; Shaping of thermoplastic polymer
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
- H05K2201/01—Dielectrics
- H05K2201/0137—Materials
- H05K2201/0141—Liquid crystal polymer [LCP]
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
- H05K2201/01—Dielectrics
- H05K2201/0137—Materials
- H05K2201/0154—Polyimide
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
- H05K2201/02—Fillers; Particles; Fibers; Reinforcement materials
- H05K2201/0203—Fillers and particles
- H05K2201/0263—Details about a collection of particles
- H05K2201/0269—Non-uniform distribution or concentration of particles
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
- H05K2201/02—Fillers; Particles; Fibers; Reinforcement materials
- H05K2201/0203—Fillers and particles
- H05K2201/0263—Details about a collection of particles
- H05K2201/0272—Mixed conductive particles, i.e. using different conductive particles, e.g. differing in shape
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
- H05K2201/03—Conductive materials
- H05K2201/0302—Properties and characteristics in general
- H05K2201/0305—Solder used for other purposes than connections between PCB or components, e.g. for filling vias or for programmable patterns
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
- H05K2201/09—Shape and layout
- H05K2201/09209—Shape and layout details of conductors
- H05K2201/095—Conductive through-holes or vias
- H05K2201/09563—Metal filled via
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
- H05K2203/03—Metal processing
- H05K2203/0307—Providing micro- or nanometer scale roughness on a metal surface, e.g. by plating of nodules or dendrites
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/38—Improvement of the adhesion between the insulating substrate and the metal
- H05K3/382—Improvement of the adhesion between the insulating substrate and the metal by special treatment of the metal
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/46—Manufacturing multilayer circuits
- H05K3/4644—Manufacturing multilayer circuits by building the multilayer layer by layer, i.e. build-up multilayer circuits
- H05K3/4652—Adding a circuit layer by laminating a metal foil or a preformed metal foil pattern
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/49002—Electrical device making
- Y10T29/49117—Conductor or circuit manufacturing
- Y10T29/49124—On flat or curved insulated base, e.g., printed circuit, etc.
- Y10T29/49155—Manufacturing circuit on or in base
- Y10T29/49165—Manufacturing circuit on or in base by forming conductive walled aperture in base
Definitions
- the present invention relates to a flexible wiring board in which wiring formed on both surfaces of an electrically insulating base material is connected by via-hole conductors, a manufacturing method thereof, a mounted product using the same, and a flexible multilayer wiring board.
- a wiring board for connecting wirings formed at both ends of an electrically insulating substrate by via-hole conductors in which holes formed in the electrically insulating substrate are filled with a conductive paste.
- a via-hole conductor is known in which metal particles containing copper (Cu) are filled instead of the conductive paste and the metal particles are fixed with an intermetallic compound. Specifically, by heating a conductive paste containing tin (Sn) -bismuth (Bi) -based metal particles and copper particles at a predetermined temperature, tin (Sn) -copper (Cu) is formed around the copper particles.
- Via hole conductors in which alloys are formed are known.
- FIG. 17 is a schematic cross-sectional view of a via hole conductor of a conventional wiring board.
- 18A and 19A are SEM photographs of a conventional via-hole conductor.
- FIG. 18B is a schematic diagram of FIG. 18A.
- FIG. 19B is a schematic diagram of FIG. 19A.
- the magnification of FIG. 18A is 3000 times, and the magnification of FIG. 19A is 6000 times.
- the via-hole conductor 2 is in contact with the wiring 1 formed on the surface of the wiring board.
- the via-hole conductor 2 has a metal part 11 and a resin part 12.
- the metal portion 11 is mainly composed of a first metal region 8 having a plurality of copper (Cu) -containing particles 3, a second metal region 9 made of tin (Sn) -copper (Cu) alloy, and the like, and bismuth (Bi). And a third metal region 10.
- Patent Document 1 is known.
- the flexible wiring board of the present invention includes an electrically insulating base material having an incompressible member having flexibility and a thermosetting member having flexibility, and a first wiring formed by sandwiching the electrically insulating substrate. And a second wiring, and a via-hole conductor that penetrates the electrically insulating substrate and electrically connects the first wiring and the second wiring.
- the via-hole conductor has a resin portion and a metal portion.
- the metal portion includes a first metal region mainly composed of copper (Cu), a second metal region mainly composed of tin (Sn) -copper (Cu) alloy, and a first metal region mainly composed of bismuth (Bi). 3 metal regions.
- the second metal region is larger than the first metal region and larger than the third metal region.
- FIG. 1A is a schematic cross-sectional view of a flexible wiring board in an embodiment of the present invention.
- FIG. 1B is a schematic cross-sectional view of the vicinity of the via-hole conductor in the embodiment of the present invention.
- FIG. 2A is a cross-sectional view showing the method for manufacturing the flexible wiring board in the embodiment of the present invention.
- FIG. 2B is a cross-sectional view illustrating the method for manufacturing the flexible wiring board in the embodiment of the present invention.
- FIG. 2C is a cross-sectional view showing the method for manufacturing the flexible wiring board in the embodiment of the present invention.
- FIG. 2D is a cross-sectional view illustrating the method for manufacturing the flexible wiring board in the embodiment of the present invention.
- FIG. 3A is a cross-sectional view illustrating the method for manufacturing the flexible wiring board in the embodiment of the present invention.
- FIG. 3B is a cross-sectional view illustrating the method for manufacturing the flexible wiring board in the embodiment of the present invention.
- FIG. 3C is a cross-sectional view showing the method for manufacturing the flexible wiring board in the embodiment of the present invention.
- FIG. 4A is a cross-sectional view showing the method for manufacturing the flexible multilayer wiring board in the embodiment of the present invention.
- FIG. 4B is a cross-sectional view showing the method for manufacturing the flexible multilayer wiring board in the embodiment of the present invention.
- FIG. 4C is a cross-sectional view showing the method for manufacturing the flexible multilayer wiring board in the embodiment of the present invention.
- FIG. 5A is a schematic cross-sectional view of the vicinity of the via-hole conductor before the via paste is compressed.
- FIG. 5B is a schematic cross-sectional view of the vicinity of the via-hole conductor after the via paste is compressed.
- FIG. 6 is a schematic diagram showing the state of via paste when a member having compressibility is used.
- FIG. 7 is a schematic view showing a state of via paste when an incompressible member is used.
- FIG. 8 is a schematic diagram showing a state of via paste when an incompressible member is used.
- FIG. 9A is a schematic diagram showing the state of the via paste before the alloying reaction.
- FIG. 9B is a schematic diagram showing a state of the via-hole conductor after the alloying reaction.
- FIG. 10 is a triangular diagram showing a metal composition in the via paste in the embodiment of the present invention.
- FIG. 11A is a diagram showing an SEM photograph of the via-hole conductor in the embodiment of the present invention.
- FIG. 11B is a schematic diagram of FIG. 11A.
- FIG. 12A is a diagram showing an SEM photograph of the via-hole conductor in the embodiment of the present invention.
- FIG. 12B is a schematic diagram of FIG. 12A.
- FIG. 13A is a diagram showing an SEM photograph of a connection portion between the metal foil and the via-hole conductor in the embodiment of the present invention.
- FIG. 13B is a schematic diagram of FIG. 13A.
- FIG. 14A is a diagram showing an SEM photograph of a connection portion between the metal foil and the via-hole conductor in the embodiment of the present invention.
- FIG. 14B is a schematic diagram of FIG. 14A.
- FIG. 15 is a diagram showing an analysis result by X-ray diffraction of the via-hole conductor in the embodiment of the present invention.
- FIG. 16A is a cross-sectional view of a mounted product using the flexible wiring board according to the embodiment of the present invention.
- FIG. 16B is a cross-sectional view of a mounted product using the flexible multilayer wiring board in the embodiment of the present invention.
- FIG. 17 is a schematic cross-sectional view of a via hole conductor of a conventional wiring board.
- FIG. 18A is a view showing an SEM photograph of a conventional via-hole conductor.
- FIG. 18B is a schematic diagram of FIG. 18A.
- FIG. 19A is a view showing an SEM photograph of a conventional via-hole conductor.
- FIG. 19B is a schematic diagram of FIG. 19A.
- the conventional via hole conductor 2 has a large volume fraction of the resin portion 12 occupying the via hole conductor 2 and a small volume fraction of the metal portion 11. Therefore, the via resistance (the resistance value of the entire via hole conductor 2) may be high.
- FIG. 1A is a schematic cross-sectional view of a flexible multilayer wiring board in an embodiment of the present invention.
- a plurality of wirings 120 formed inside the electrically insulating base material 130 are electrically connected via via-hole conductors 140 to constitute a flexible multilayer wiring board 110.
- FIG. 1B is a schematic cross-sectional view of the vicinity of the via-hole conductor 140 in the embodiment of the present invention.
- the flexible multilayer wiring board 110 includes an electrically insulating base material 130 having an incompressible member 220 and a thermosetting adhesive layer (thermosetting member) 210, a first wiring 120a, a second wiring 120b, and a via hole. And a conductor 140.
- the first wiring 120a and the second wiring 120b are formed with the electrically insulating base material 130 interposed therebetween.
- the via-hole conductor 140 penetrates the electrically insulating base material 130 and electrically connects the first wiring 120a and the second wiring 120b.
- the electrically insulating substrate 130 has an incompressible member 220 such as a heat resistant film, and a thermosetting adhesive layer 210 formed on both surfaces of the incompressible member 220.
- a first wiring 120 a and a second wiring 120 b obtained by patterning a metal foil 150 such as a copper foil into a predetermined shape are bonded to the incompressible member 220 through a thermosetting adhesive layer 210.
- the thermosetting adhesive layer 210 may be formed only on one surface of the incompressible member 220.
- the metal foil 150 is preferably a copper foil having a roughened surface. By roughening, the adhesiveness between the metal foil 150 and the via-hole conductor 140 is increased, so that the reliability is increased. Depending on the application, the metal foil 150 without roughening treatment may be used.
- the via-hole conductor 140 has a metal part 190 and a resin part 200.
- the metal portion 190 has a first metal region 160 mainly composed of copper, a second metal region 170 mainly composed of a tin-copper alloy, and a third metal region 180 mainly composed of bismuth. Second metal region 170 is larger than first metal region 160 and larger than third metal region 180.
- Resin portion 200 is an epoxy resin or the like. Epoxy resins are excellent in reliability.
- the resin portion 200 is mainly a cured product of the resin added to the via paste, but a part of the thermosetting resin constituting the thermosetting adhesive layer 210 may be mixed therein.
- the size (or volume fraction or weight fraction) of the second metal region 170 is larger than the size (or volume fraction or weight fraction) of the first metal region 160. Furthermore, the size (or volume fraction or weight fraction) of the second metal region 170 is larger than the size (or volume fraction or weight fraction) of the third metal region 180.
- the plurality of wirings 120 are electrically connected with the second metal region 170 as a main component. it can. Furthermore, the first metal region 160 and the third metal region 180 can be scattered in the second metal region 170 without being in contact with each other (or scattered in a small islet state).
- the second metal region 170 has an intermetallic compound Cu 6 Sn 5 and an intermetallic compound Cu 3 Sn, and the ratio of Cu 6 Sn 5 / Cu 3 Sn is 0.001 or more and 0.100 or less.
- the ratio of Cu 6 Sn 5 / Cu 3 Sn is preferably 0.100 or less. It is more desirable to set it to 0.001 or more and 0.100 or less.
- the reaction time is finite, and the reaction time is practically 10 hours or less at the longest. Therefore, in such a finite reaction time, the ratio of Cu 6 Sn 5 / Cu 3 Sn is unlikely to be completely zero, and it is difficult to quantitatively analyze Cu 6 Sn 5 that will remain slightly. Become.
- the ratio of Cu 6 Sn 5 / Cu 3 Sn is 0 or more and 0.100 or less (note that 0 is below the detection limit of the measuring device or could not be detected by the measuring device). Including cases). Note that when the measurement accuracy of the measurement device is sufficiently high, the ratio of Cu 6 Sn 5 / Cu 3 Sn may be 0.001 or more and 0.100 or less.
- the ratio of Cu 6 Sn 5 / Cu 3 Sn is preferably 0.001 or more and 0.100 or less is the result of evaluation using an XRD (X-ray diffractometer).
- XRD X-ray diffractometer
- XRD is a kind of mass analysis and EPMA is a kind of cross-sectional analysis, but there is substantially no difference. From the above, when measuring the ratio of Cu 6 Sn 5 / Cu 3 Sn in the fine via portion (or via paste portion), select one of XRD, XMA, EPMA, or a similar device for evaluation. That's fine.
- the electrically insulating substrate 130 has an incompressible member 220 such as a heat resistant film and a thermosetting adhesive layer 210 formed on at least one surface thereof.
- a member using a woven fabric or a nonwoven fabric in which a plurality of fibers are entangled with each other as a core material, whether glass fiber or resin fiber, has compressibility. This is because a through-hole is formed in a core material using a woven fabric or non-woven fabric, and when this through-hole is filled with a conductive paste and pressed, it is pressed against metal particles contained in the conductive paste. This is because the through hole is deformed or widened.
- a member using a film as a core material since a member using a film as a core material has no space inside, it has incompressibility. This is because a through-hole is formed in a core material using a film, and when the through-hole is filled with a conductive paste and pressed, the diameter of the through-hole does not substantially change.
- the tip of the woven fabric or nonwoven fabric made of glass fiber around the hole may melt and harden, Even in this case, the core material has compressibility.
- the reason for this is that the presence of glass fiber melted and integrated with a laser or the like is limited only to the periphery of the hole, and the glass fiber in the other part (that is, the part slightly away from the through hole formed by the laser) This is because they are only intertwined with each other. Moreover, it is because all the glass fibers exposed around the hole do not melt and become one.
- the entangled portions of the fibers may be fixed. Even in this case, the member having the nonwoven fabric as the core material has compressibility.
- the incompressible member 220 has excellent incompressibility because it does not have a bubble portion or the like for expressing compressibility inside.
- the via paste By using an incompressible member, the via paste can be compressed at a high pressure. As a result, a via-hole conductor 140 having a metal portion 190 of 74.0 vol% or more and 99.5 vol% or less can be manufactured. Moreover, the via-hole conductor 140 having the resin portion 200 of 0.5 vol% or more and 26.0 vol% or less can be manufactured.
- the via resistance means a resistance value of the entire via-hole conductor 140.
- connection resistance between the wiring 120 and the via-hole conductor 140 is reduced by increasing the contact area between the wiring 120 and the via-hole conductor 140. Therefore, it is preferable to reduce the volume fraction of the resin part 200 at the interface part between the wiring 120 and the via-hole conductor 140.
- the specific resistance of the via-hole conductor 140 can be set to 1.00 ⁇ 10 ⁇ 7 ⁇ ⁇ m or more and 5.00 ⁇ 10 ⁇ 7 ⁇ ⁇ m or less, so that the via resistance is stable. Turn into.
- the resin part 200 which comprises the via-hole conductor 140 consists of hardened
- the curable resin is not particularly limited, specifically, for example, it is preferable to use a cured product of an epoxy resin that is excellent in heat resistance and has a low linear expansion coefficient.
- the incompressible member 220 has flexibility
- the thermosetting adhesive layer 210 also has flexibility.
- the thermosetting adhesive layer 210 it is desirable to use an insulating member having an elastic modulus at 25 ° C. (room temperature) after bonding (or after curing) of 0.1 GPa or more and 10.0 GPa or less. Furthermore, it is desirable to use an insulating member having an elastic modulus of 0.1 GPa or more and 10.0 GPa or less at 0 ° C., further ⁇ 20 ° C. (20 ° C. below freezing point).
- a viscoelasticity measuring device DMS manufactured by SII Nanotechnology Inc. (SII) is used.
- the thickness of the thermosetting adhesive layer 210 is preferably 0.1 to 10 times the thickness of the incompressible member 220. Furthermore, 0.5 times or more and 4.0 times or less are more desirable.
- thermosetting adhesive layer 210 having an elastic modulus at 25 ° C. (room temperature) of 0.1 GPa or more and 10.0 GPa or less, a flexible multilayer having excellent flexibility.
- a wiring substrate 110 is obtained.
- vias can also be formed at locations where the flexible multilayer wiring board 110 is bent.
- the flexible multilayer wiring board 110 shown in FIG. 1A is an example of four layers, it is not necessary to limit to four layers, and any number of layers may be used.
- the surface layer wiring 120 may be a roughened metal foil 150 before patterning.
- the surface of the flexible multilayer wiring board 110 can be used as a kind of shield board by using the metal foil 150 before patterning.
- Such a shield substrate is also an example of the flexible multilayer wiring substrate 110 of the present embodiment.
- the surface of the metal foil 150 has irregularities representing the roughened surface at the interface with the thermosetting adhesive layer 210. Further, irregularities representing the roughened surface are also shown on the surface of the metal foil 150 at the interface with the via-hole conductor 140. However, the roughened surface at the interface portion between the metal foil 150 and the via-hole conductor 140 may be less rough than the roughened surface at the interface portion between the metal foil 150 and the thermosetting adhesive layer 210. This is because by roughening the surface of the metal foil 150, the alloying reaction between the via-hole conductor 140 and the metal foil 150 is promoted, and the unevenness on the surface of the metal foil 150 is reduced.
- the unevenness of the metal foil 150 may disappear due to an alloying reaction between the roughened surface of the metal foil 150 and the via-hole conductor 140.
- the reduction of the rough surface means that a physically strong alloying reaction (metal bonding) proceeds.
- the flexible multilayer wiring board 110 can be bent at an arbitrary place.
- FIGS. 3A to 3C are cross-sectional views showing a method for manufacturing the flexible wiring board 600.
- FIG. 4A to 4C are cross-sectional views showing a method for manufacturing the flexible multilayer wiring board 111.
- FIG. The uncured base material 230 includes an incompressible member 220 having a thickness of 55 ⁇ m or less, and an uncured thermosetting adhesive layer 210 formed on both surfaces of the incompressible member 220.
- protective films 240 are bonded to both surfaces of the uncured base material 230.
- the incompressible member 220 can obtain sufficient insulation even when the thickness is 50 ⁇ m or less, 30 ⁇ m or less, 15 ⁇ m or less, and even 6 ⁇ m or less.
- the incompressible member 220 is easily bent as the thickness is reduced. However, if the thickness of the incompressible member 220 becomes too thin, the degree of bending may change due to repeated use. In such a case, an incompressible member 220 having a thickness and rigidity corresponding to the intended use may be selected. Further, the thermosetting adhesive layer 210 used together with the incompressible member 220, which is an incompressible member, may have a thickness and an elastic modulus that are required according to the intended use.
- the incompressible member 220 thicker than 55 ⁇ m it has a certain degree of flexibility. However, in this case, it is desirable to use the roughened metal foil 150. Since the adhesion between the via-hole conductor 140 and the metal foil 150 is increased by using the roughened metal foil 150, even when the thick incompressible member 220 is used or when strict reliability is required. The via-hole conductor 140 and the metal foil 150 are not easily peeled off, and the flexible multilayer wiring board 111 having sufficient flexibility can be obtained.
- the incompressible member 220 for example, a polyimide film, a liquid crystal polymer film, a polyether ether ketone film, or the like is used.
- a polyimide film is particularly preferable, but is not particularly limited as long as it is a resin sheet that can withstand the soldering temperature.
- the incompressible member 220 has excellent incompressibility because it does not have a bubble portion or the like that causes compressibility.
- thermosetting adhesive layer 210 an uncured adhesive layer made of an epoxy resin or the like is used.
- the thickness of one side of the thermosetting adhesive layer is preferably 1 ⁇ m or more and 30 ⁇ m or less, more preferably 5 ⁇ m or more and 10 ⁇ m or less.
- the thermosetting adhesive layer 210 desirably has an elastic modulus of 0.1 GPa or more and 10.0 GPa or less at 25 ° C. (room temperature) after bonding (or after curing). Furthermore, it is desirable that the elastic modulus is 0.1 GPa or more and 5.0 GPa or less.
- the thickness of the thermosetting adhesive layer 210 is desirably 0.1 to 10 times the thickness of the incompressible member 220. Furthermore, the thickness of the thermosetting adhesive layer 210 is desirably 0.5 times or more and 4.0 times or less the thickness of the incompressible member.
- the protective film for example, a resin film such as PET (polyethylene terephthalate) or PEN (polyethylene naphthalate) is used.
- the thickness of the resin film is preferably 0.5 ⁇ m or more and 50 ⁇ m or less, and more preferably 1 ⁇ m or more and 30 ⁇ m or less. By setting it as such thickness, the protrusion part which consists of via paste of sufficient height can be exposed by peeling of a protective film so that it may mention later.
- the surface tackiness (or adhesive force) of the uncured substrate 230 or the thermosetting adhesive layer 210 on the surface of the uncured substrate 230 is used.
- a method of directly bonding is used.
- a through-hole 250 is formed by perforating the uncured base material 230 on which the protective film 240 is disposed from the outside of the protective film 240.
- various methods such as drilling using a drill as well as non-contact processing methods such as a carbon dioxide laser and a YAG laser are used.
- the diameter of the through hole is 10 ⁇ m or more and 500 ⁇ m or less, and further 50 ⁇ m or more, 300 ⁇ m or less, 80 ⁇ m or more, 120 ⁇ m or less.
- the via paste 260 includes copper particles 290, Sn—Bi solder particles 300 containing Sn and Bi, and a thermosetting resin component (organic component) 310 such as an epoxy resin (see FIG. 5A).
- the filling method of the via paste 260 is not particularly limited, for example, a method such as screen printing is used.
- a part of the via paste 260 is protruded from the through hole 250 (see FIG. 2B) as a protruding portion 270.
- a substrate 500 is manufactured.
- the height h of the protrusion 270 depends on the thickness of the protective film, it is preferably 0.5 ⁇ m or more and 50 ⁇ m or less, and more preferably 1 ⁇ m or more and 30 ⁇ m or less. If the protruding portion 270 is too high, the paste may overflow around the through-hole 250 on the surface of the uncured base material 230 in the pressurizing step described later, and the surface smoothness may be lost. In addition, when the protruding portion 270 is too low, pressure may not be sufficiently applied to the via paste filled in the pressurizing process described later.
- the metal foil 150 is placed on the uncured base material 230 and pressed in the direction indicated by the arrow 280. At the time of pressurization, a force is applied to the protruding portion 270 via the metal foil 150, so that the via paste 260 filled in the through hole 250 is compressed with a high pressure.
- the incompressible member 220 is used as a part of the uncured base material 230, the diameter of the through hole 250 does not widen and is strong against the via paste 260 at the time of pressurization (further heating) indicated by an arrow 280. Pressure is applied. As a result, the distance between the copper particles and the Sn—Bi particles contained in the via paste 260 is reduced, and they are in close contact with each other. Therefore, the ratio of the resin part in the via paste 260 is reduced. In other words, the ratio of the metal part in the via paste 260 increases.
- the metal portion 190 has a first metal region 160 mainly composed of copper, a second metal region 170 mainly composed of tin-copper alloy, and a third metal region 180 mainly composed of bismuth. (See FIG. 1B).
- the size (or volume% or weight%) of the second metal region 170 is made larger than the size (or volume% or weight%) of the first metal region 160. Further, the size (or volume% or weight%) of the second metal region 170 is made larger than the size (or volume% or weight%) of the third metal region 180. As a result, the reliability of the via-hole conductor 140 increases and the strength increases.
- the reliability of the via-hole conductor 140 can be improved by interposing the first metal region 160 and the third metal region 180 in the second metal region 170 without being in contact with each other.
- the second metal region 170 includes an intermetallic compound Cu 6 Sn 5 and an intermetallic compound Cu 3 Sn, and a ratio of Cu 6 Sn 5 / Cu 3 Sn is set to 0.001 or more and 0.100 or less. The reliability of the via-hole conductor 140 can be improved.
- the pressurizing conditions are not particularly limited, it is preferable to set the mold temperature from room temperature (20 ° C.) to a temperature below the melting point of the Sn—Bi solder particles. Moreover, in this pressurization process, in order to advance hardening of the thermosetting contact bonding layer 210, you may use the heating press heated to the temperature required in order to advance hardening.
- a photoresist film is formed on the surface of the metal foil 150. Then, the photoresist film is exposed through a photomask. Thereafter, development and rinsing are performed, and a photoresist film is selectively formed on the surface of the metal foil 150. Then, the metal foil 150 not covered with the photoresist film is removed by etching. Thereafter, the photoresist film is removed. In this way, the wiring 120a (first wiring) and the wiring 120b (second wiring) are formed, and the flexible wiring board 600 is obtained.
- a liquid resist or a dry film may be used for the formation of the photoresist film.
- 4A to 4C are cross-sectional views illustrating a method of further multilayering the flexible wiring board 600 produced in FIG. 3C.
- a substrate 500 (see FIG. 2D) having protrusions 270 is arranged on both sides of the flexible wiring substrate 600 produced in FIG. 3C.
- a laminated body as shown to FIG. 4B is obtained by pinching
- the metal foil 150 is patterned to form the upper layer wiring 121a and the lower layer wiring 121b, thereby forming the flexible multilayer wiring board 111.
- the flexible multilayer wiring substrate 111 in which the upper layer wiring 121a and the lower layer wiring 121b are connected via the via-hole conductor 140 is obtained.
- a flexible multilayer wiring board 110 to which a plurality of wirings as shown in FIG. 1A are connected is obtained.
- FIGS. 5A and 5B are schematic cross-sectional views before and after compression around the through hole 250 of the uncured base material 230 filled with the via paste 260.
- FIG. 5A shows before compression
- FIG. 5B shows after compression.
- FIG. 5A corresponds to an enlarged view of the via paste 260 in FIG. 3A.
- the average particle diameter of the copper particles 290 is preferably 0.1 ⁇ m or more and 20 ⁇ m or less, and more preferably 1 ⁇ m or more and 10 ⁇ m or less.
- the tap density (JIS X 2512) of the copper particles 290 is reduced, so that the via paste having the copper particles 290 in the through holes 250 (see FIG. 2B) is high. It tends to be difficult to fill and expensive.
- the average particle diameter of the copper particles 290 is too large, when the via-hole conductor 140 having a diameter as small as 100 ⁇ m or less, more preferably 80 ⁇ m or less is to be formed, it tends to be difficult to fill.
- the particle shape of the copper particles 290 for example, a spherical shape, a flat shape, a polygonal shape, a scale shape, a flake shape, or a shape having protrusions on the surface is used, but the particle shape is not limited thereto. Moreover, a primary particle may be sufficient and the secondary particle may be formed.
- the Sn-Bi solder particles 300 mean solder particles 300 containing Sn and Bi. Further, by adding indium (In), silver (Ag), zinc (Zn), or the like to the solder particles 300, wettability, fluidity, and the like may be improved.
- the Bi content in the Sn—Bi solder particles 300 is preferably 10% or more and 58% or less, more preferably 20% or more and 58% or less.
- the melting point (eutectic point) is preferably 75 ° C. or higher and 160 ° C. or lower, more preferably 135 ° C. or higher and 150 ° C. or lower.
- Sn—Bi solder particles 300 two or more types of particles having different compositions may be used in combination. Among these, Sn-58Bi solder particles 300, which are lead-free solder having a low eutectic point of 138 ° C., are particularly preferable from the viewpoint of the environment.
- the average particle size of the Sn—Bi solder particles 300 is preferably 0.1 ⁇ m or more and 20 ⁇ m or less, more preferably 2 ⁇ m or more and 15 ⁇ m or less.
- the average particle size of the Sn—Bi solder particles is too small, the specific surface area becomes large and the ratio of the oxide film on the surface becomes large, so that it becomes difficult to melt.
- the via paste 260 to the through hole 250 is difficult to fill.
- thermosetting resin component 310 for example, glycidyl ether type epoxy resin, alicyclic epoxy resin, glycidyl amine type epoxy resin, glycidyl ester type epoxy resin, or other modified epoxy resins are used.
- the thermosetting resin component 310 may contain a curing agent.
- curing agent is not specifically limited, It is preferable to use the hardening
- a curing agent acts as a curing catalyst for the epoxy resin and reduces the contact resistance at the time of bonding by reducing the copper film and the oxide film present on the surface of the Sn—Bi solder particles 300.
- an amine compound having a boiling point higher than the melting point of the Sn—Bi solder particles is preferable because the contact resistance during bonding is reduced.
- Examples of such amine compounds include 2-methylaminoethanol, N, N-diethylethanolamine, N, N-dibutylethanolamine, N-methylethanolamine, N-methyldiethanolamine, N-ethylethanolamine, N -Butylethanolamine, diisopropanolamine, N, N-diethylisopropanolamine, 2,2'-dimethylaminoethanol, triethanolamine and the like.
- Via paste 260 is obtained by mixing copper particles 290, Sn—Bi solder particles 300 containing Sn and Bi, and a thermosetting resin component 310 such as an epoxy resin. Specifically, for example, it is obtained by adding copper particles and Sn—Bi solder particles to a resin varnish containing an epoxy resin, a curing agent and a predetermined amount of an organic solvent, and mixing them with a planetary mixer or the like.
- the ratio of the thermosetting resin component 310 in the via paste 260 is 0.3% by mass or more and 30% by mass or less, and more preferably 3% by mass or more and 20% by mass or less in order to obtain a low resistance value. In addition, it is preferable from the viewpoint of securing sufficient workability.
- the weight ratio of Cu, Sn, and Bi in the paste is shown in a triangular diagram as shown in FIG. , A, B, C, and D are preferably included so as to be in a region surrounded by a quadrangle having apexes.
- the content ratio of the copper particles 290 with respect to the total amount of the copper particles 290 and the Sn-58Bi solder particles 300 is: It is preferable that they are 22 mass% or more and 80 mass% or less, Furthermore, they are 40 mass% or more and 80 mass% or less.
- the protruding portion 270 protruding from the through hole 250 formed in the uncured base material 230 is pressed through the metal foil 150 as indicated by an arrow 280a.
- the via paste 260 filled in the through hole 250 (see FIG. 2B) is compressed.
- a considerable portion of the thermosetting resin component 310 in the via paste 260 is pushed out of the through hole 250 as indicated by an arrow 280b.
- the copper particles 290 and the Sn—Bi solder particles 300 are alloyed by heating, and the metal portion after alloying becomes 74 vol% or more, 80 vol% or more, and further 90 vol% or more in the via-hole conductor.
- the incompressible member 220 When the via paste 260 is filled, pressurized, and heated, the incompressible member 220 is formed so that the through hole 250 (see FIG. 2B) is less likely to spread or deform under pressure from the via paste 260. Is used.
- FIG. 6 is a schematic diagram showing the state of via paste when a member having compressibility is used as the electrically insulating substrate.
- the compressible member 340 for example, a prepreg in which glass fiber, aramid fiber, or the like is used as the core material 320 and the core material 320 is impregnated with a semi-cured resin 330 made of epoxy resin or the like is used.
- the prepreg exhibits compressibility due to the presence of a gap between the fibers of the core material, a gap between the core material and the semi-cured resin, or voids (for example, air bubbles) contained in the semi-cured resin. That is, the cured product of prepreg is incompressible, but prepreg has compressibility.
- the resin in a semi-cured state softens and fills the gaps between the fibers of the core material, the core material and the resin, or the voids contained in the resin (for example, air bubbles). It is.
- the compressible member 340 Since the compressible member 340 has bubbles (or voids) or the like inside, when compressed, its thickness is compressed by about 10% to 30%.
- a compressive member 340 When a compressive member 340 is formed with a through-hole serving as a via, filled with via paste, provided with a protrusion, and then pressurized, the diameter (or cross-sectional area) of the pressurized through-hole is Compared to 10% to 20%.
- an arrow 280c indicates a state in which the diameter of the through hole 250 is increased (or the diameter of the through hole 250 is expanded or deformed) when the via paste 260 is compressed and compressed as indicated by an arrow 280a. ing.
- the volume fraction when the sphere is irregularly placed in the container is about 64% at maximum as “random fine packing” (for example, Nature 435, 7195 (May 2008), Song et al.).
- random fine packing for example, Nature 435, 7195 (May 2008), Song et al.
- thermosetting remaining in the gaps between the plurality of copper particles 290 and the plurality of solder particles 300 It is difficult to drive the conductive resin component 310 out of the via paste 260.
- the via paste 260 may not be sufficiently compressed even when a high pressure is applied.
- an incompressible member for example, a film base material
- a through hole to be a via is formed in the thermosetting adhesive layer incompressible member
- a via paste is filled, a protrusion is provided, and then pressurization is performed.
- the diameter (or cross-sectional area) of the through hole after pressurization hardly changes compared with that before pressurization.
- the amount of change is suppressed to less than 3%.
- the via paste can be sufficiently compressed without using special equipment. This is because in the case of an incompressible member, even if the through hole cuts a part of the incompressible member, the incompressible member is hardly unwound or spreads.
- the via paste 260 may not be sufficiently compressed even when a high pressure is applied using the protrusion 270.
- FIG 7 and 8 are schematic views showing the state of the via paste when an incompressible member is used.
- thermosetting resin component 310 in the via paste 260 By using an incompressible member 220 such as a heat-resistant film as the uncured base material 230, the flow component of the thermosetting resin component 310 in the via paste 260 (for example, an insulating component such as an organic component) is transferred to the via-hole conductor 140. Can be kicked out of. As a result, the volume fraction of the thermosetting resin component 310 in the via paste 260 can be reduced.
- the diameter of the through hole 250 (see FIG. 2B) hardly expands even when a pressure as indicated by an arrow 280 a is applied to the via paste 260.
- the pressure indicated by the arrow 280a increases, the copper particles 290 and the solder particles 300 contained in the via paste 260 come into surface contact with each other over a wider area while deforming each other. Therefore, the volume fraction of the metal part 190 in the via-hole conductor 140 can be higher than 70 vol%, more preferably 80 vol% or higher and 90 vol% or higher.
- the hardness of the copper particles 290 and the solder particles 300 be different in order to bring the copper particles 290 and the solder particles 300 into surface contact with each other over a wider area while deforming each other.
- the slip (or slip) between the powders can be reduced.
- the solder particles 300 are deformed while maintaining a state of being sandwiched between the plurality of copper particles 290, and the flow components (for example, Insulating components such as organic components) can be driven out of the via-hole conductor 140.
- the volume fraction of the thermosetting resin component 310 in the via paste 260 can be further reduced.
- the via paste 260 when the via paste 260 is pressurized and compressed from the outside of the metal foil 150 as indicated by an arrow 280a, the fluid component in the via paste 260, that is, the thermosetting resin component 310 is not It flows out to the thermosetting adhesive layer 210 provided on the surface of the compressible member 220. As a result, as shown in FIG. 8, the filling rate of the copper particles 290 and the solder particles 300 in the via paste 260 is increased. 7 and 8, the state in which the copper particles 290 and the solder particles 300 are compressed, deformed, and brought into surface contact with each other is not shown. Further, the protruding portion 270 formed by the via paste 260 formed on the metal foil 150 is not shown.
- the pressure (arrow 280 c) due to the thermosetting resin component 310 in the via paste 260 exceeds the pressure (arrow 280 d) from the thermosetting adhesive layer 210, and the thermosetting resin component 310 is in the through hole 250. It shows how it flows out.
- the thermosetting resin component 310 in the via paste 260 can be discharged out of the via paste 260, and the volume fraction of the thermosetting resin component 310 in the via paste 260. Can be greatly reduced.
- the volume fraction of metal components such as copper particles 290 and solder particles 300 in the via paste 260 is increased by the amount of the thermosetting resin component 310 contained in the via paste 260.
- the volume fraction of the metal portion 190 in the via-hole conductor 140 can be increased to 74 vol% or more.
- the via paste 260 can be highly compressed according to the protrusion of the via paste 260.
- the difference in diameter (or cross-sectional area) of the through-holes before and after pressurization is preferably less than 3%, and more preferably less than 2%.
- the volume fraction of the metal part 190 after alloying composed of the copper particles 290 and the solder particles 300 can be set to 74.0 vol% or more and 99.5 vol% or less.
- the volume fraction of the resin part 200 which is a part excluding the metal part 190, can be reduced to 0.5 vol% or more and 26.0 vol% or less.
- the resin portion 200 may be a resin portion included in the via-hole conductor 140, and may not be the thermosetting resin component 310 included in the via paste 260.
- the thermosetting resin component 310 and the thermosetting adhesive layer 210 in the via paste 260 may be compatible with each other or may be melted together.
- the via paste 260 is filled in the through-holes 250 formed in the incompressible member 220 and the thermosetting adhesive layer 210 and is pressurized, whereby the content of the thermosetting resin component 310 in the via paste ( Alternatively, the volume fraction) can be further reduced. Therefore, the filling rate (or volume fraction) of copper particles 290, solder particles 300, etc. in via paste 260 can be increased. As a result, the contact area between the copper particles 290 and the solder particles 300 increases, the alloying reaction is promoted, and the proportion of the metal portion in the via-hole conductor 140 can be increased.
- thermosetting resin component 310 Next, how the alloying reaction between copper particles and solder particles is promoted by reducing the volume fraction of the thermosetting resin component 310 will be described.
- FIG. 9A is a schematic diagram showing the state of the via paste before the alloying reaction.
- FIG. 9B is a schematic diagram showing a state of the via-hole conductor after the alloying reaction.
- the copper particles 290 and the solder particles 300 are compressed with each other and packed with high density as indicated by an arrow 280. At this time, it is desirable that the copper particles 290 and the solder particles 300 are deformed and in surface contact with each other. As the area where the copper particles 290 and the solder particles 300 are in contact with each other is wider, the alloying reaction between the copper particles 290 and the solder particles 300 (and the intermetallic compound formation reaction) proceeds more uniformly in a shorter time. .
- the volume fraction of the thermosetting resin component 310 contained in the via paste 260 is 0.5 vol% or more and 26 vol% or less (further 20 vol% or less, and further 10 vol% or less).
- the metal paste 150 is pressure-bonded to the uncured base material 230, and a predetermined pressure is applied to the protruding portion 270 of the via paste 260 through the metal foil 150, whereby the via paste 260 is pressurized and compressed.
- the copper particles 290 or the copper particles 290 and the solder particles 300 can be in surface contact with each other, and the alloying reaction is promoted.
- Projections 270 are formed on the upper and lower surfaces of the via paste 260 in FIG. 9A. Further, the upper and lower surfaces of the via-hole conductor 140 in FIG. 9B are flat with no protrusions. Thus, it is desirable that the upper and lower surfaces of the via paste 260 become flat after the alloying reaction. Conventionally, when an incompressible member is used, the protruding portion of the via-hole conductor may remain even after the alloying reaction, making it difficult to mount the component. However, by making the alloying reaction proceed very fast as in the present embodiment, the volume fraction of the metal portion 190 in the via-hole conductor 140 can be made 74.0 vol% or more and the via-hole conductor can be made flat. .
- the volume fraction of the resin portion 200 in the via-hole conductor 140 can be set to 26.0 vol% or less.
- the height of the protrusion 270 (h in FIG. 2D) is desirably 2 ⁇ m or more, more preferably 5 ⁇ m or more, or 0.5 times or more of the thickness of the metal foil 150.
- copper is used even when an incompressible member is used for the electrically insulating base material 130.
- the volume fraction in the via paste 260 such as the particles 290 and the solder particles 300 may not be 74 vol% or more.
- the particle diameters of the copper particles 290 and the solder particles 300 may be different from each other, or the copper particles 290 having different particle diameters may be mixed.
- the specific surface area of the powder is increased and the viscosity of the via paste 260 is increased.
- the viscosity of the via paste 260 increases and affects the filling property to the through holes 250.
- the copper particles 290 and the solder particles 300 have the same particle size.
- FIG. 9B shows a state after the copper particles 290 deformed and in surface contact with each other and the solder particles 300 undergo an alloying reaction (and further an intermetallic compound formation reaction).
- the via-hole conductor 140 has a metal portion 190 and a resin portion 200.
- the metal portion 190 has a first metal region 160 mainly composed of copper, a second metal region 170 mainly composed of a tin-copper alloy, and a third metal region 180 mainly composed of bismuth.
- the metal part 190 and the resin part 200 constitute a via-hole conductor 140.
- the resin portion 200 is a cured resin including an epoxy resin.
- Second metal region 170 has a larger cross-sectional area, volume fraction, or weight fraction than first metal region 160. Furthermore, the second metal region 170 has a larger cross-sectional area, volume fraction, or weight fraction than the third metal region 180.
- the metal foils 150 forming the plurality of wirings 120 are electrically connected via the second metal region 170.
- the first metal region 160 and the third metal region 180 are scattered in the second metal region 170 without being in contact with each other, so that the reliability of the via-hole conductor 140 is increased.
- the second metal region 170 includes an intermetallic compound Cu 6 Sn 5 and an intermetallic compound Cu 3 Sn, and a ratio of Cu 6 Sn 5 / Cu 3 Sn is set to 0.001 or more and 0.100 or less. The reliability of the via-hole conductor 140 is increased.
- the height of the protruding portion 270 of the metal foil 150 after alloying can be lowered by continuing the pressure compression indicated by the arrow 280.
- the volume fraction of the resin portion 200 occupying the via-hole conductor 140 can be reduced, and the thickness variation of the flexible multilayer wiring board 110 can be reduced.
- the flatness and smoothness of the flexible multilayer wiring board 110 can be improved, the mounting property of bare chips such as semiconductor chips is enhanced.
- the second metal region 170 includes the intermetallic compound Cu 6 Sn 5 and the intermetallic compound Cu 3 Sn.
- the ratio of Cu 6 Sn 5 / Cu 3 Sn to 0.001 or more and 0.100 or less, for example, generation of voids 5a (see FIG. 17) such as Kirkendyl voids can be suppressed.
- the contact area between the copper particles 290 and the solder particles 300 is wide.
- the volume fraction of the thermosetting resin component 310 in the via paste 260 is 26 vol% or less (more 20 vol% or less, and further 10 vol% or less). Is desirable.
- the ratio of Cu 6 Sn 5 / Cu 3 Sn can be suppressed to 0.100.
- the density of the copper particles 290 and the Sn—Bi solder particles 300 filled in the through holes 250 is increased.
- the compressed via paste 260 is heated to a Sn-Bi solder particle 300 temperature range from the eutectic temperature of the Sn-Bi solder particles 300 to a temperature not higher than the eutectic temperature by 10 ° C. It is useful to melt a part of the Bi-based solder particles 300 and subsequently heat it to a temperature range of 20 ° C. to 300 ° C. higher than the eutectic temperature.
- the growth of the second metal region 170 can be promoted by such pressurization and heating. Furthermore, it is preferable to carry out these in one step with continuous pressure bonding and heating. By performing the process in one continuous process, the formation reaction of each metal region can be further stabilized, and the structure of the via itself can be stabilized.
- the via paste 260 is gradually heated to a temperature equal to or higher than the eutectic temperature of the Sn—Bi solder particles 300.
- a part of the Sn—Bi solder particles 300 melts at a composition ratio that melts at that temperature.
- a second metal region 170 mainly composed of tin or a tin-copper alloy is formed on or around the copper particles 290.
- the surface contact portion where the copper particles 290 are in surface contact may also be changed to a part of the second metal region 170.
- the total weight ratio of the first metal region 160 and the second metal region 170 to the entire via-hole conductor 140 is preferably in the range of 20% to 90%.
- the via resistance may increase or a predetermined compressed state may not be obtained.
- it may be technically difficult to exceed 90%.
- the Sn-Bi solder particles 300 start to partially melt.
- the composition of the solder to be melted is determined by the temperature, and Sn that is difficult to melt at the temperature at the time of heating remains as an Sn solid phase body.
- the copper particles 290 come into contact with the molten solder and the surface is wetted with the molten Sn—Bi-based solder, Cu and Sn interdiffusion proceeds at the interface of the wet portion, and the Sn—Cu compound layer Etc. are formed. In this way, the proportion of the second metal region 170 in the via-hole conductor 140 can be made larger than that of the first metal region 160 and larger than that of the third metal region 180.
- Sn in the molten solder decreases due to the further progress of the formation of the Sn—Cu compound layer and the like and the mutual diffusion. Since the decreased Sn in the molten solder is compensated from the Sn solid layer, the molten state continues to be maintained. Further, when Sn decreases and the ratio of Sn and Bi becomes larger than that of Sn-58Bi, Bi begins to segregate, and the third metal region 180 is formed as a solid phase body containing bismuth as a main component.
- the melting point of Sn—Bi solder is 140 ° C. or lower, which is lower than the general solder reflow temperature when electronic components are surface-mounted. Therefore, when only Sn—Bi solder is used as a via hole conductor of a circuit board as a single unit, the via resistance may fluctuate due to remelting of the solder of the via hole conductor during solder reflow.
- FIG. 10 is a triangular diagram showing an example of the metal composition in the via paste of this embodiment.
- the metal composition in the via paste of the present embodiment is represented by the weight composition ratio (Cu: Sn: Bi) of Cu, Sn, and Bi as A (0.37: 0.567: 0.063), B (0.22: 0.3276: 0.4524), C (0.79: 0.09: 0.12), D (0.89: 0.10: 0.01) It is desirable that the region be surrounded by a quadrangle as a vertex.
- C (0.79: 0.09: 0.12), D (0.89: 0.10: 0.01), E (0.733: 0.240: 0.027), F It is desirable that the region be surrounded by a quadrangle having (0.564: 0.183: 0.253) as a vertex.
- the via resistance can be reduced by making the area surrounded by a quadrangle.
- the intermetallic compound Cu 6 Sn 5 and the intermetallic compound Cu 3 Sn are included, and the ratio of Cu 6 Sn 5 / Cu 3 Sn can be easily set to 0.100 or less.
- the composition of the Sn—Bi solder particles 300 is higher than that of the eutectic Sn—Bi solder composition (Bi 58% or less, Sn 42% or more). .
- a part of the solder composition melts in a temperature range of 10 ° C. or higher from the eutectic temperature of the Sn—Bi solder particles, while Sn that does not melt remains.
- the remaining Sn diffuses and reacts on the copper particle surface.
- the Sn concentration decreases from the Sn—Bi solder particles 300, so that the remaining Sn melts.
- the third metal region 180 is formed as a solid phase body mainly composed of. And by making the 3rd metal area
- the temperature at which the compressed via paste 260 is heated is equal to or higher than the eutectic temperature of the Sn—Bi solder particles 300 and is particularly limited as long as it does not decompose the components of the uncured base material 230.
- the Sn-58Bi solder particles 300 are first heated to a temperature range of 139 ° C. to 149 ° C. It is preferable that after a part of is melted, it is gradually heated to a temperature range of about 159 ° C. or more and 230 ° C. or less.
- the thermosetting resin component contained in the via paste 260 is cured by appropriately selecting the temperature.
- Resin sheet (uncured base material 230): polyimide film (non-compressible member 220 of length 500 mm ⁇ width 500 mm, thickness 10 ⁇ m to 50 ⁇ m) ), An uncured epoxy resin layer (thermosetting adhesive layer 210) having a thickness of 10 ⁇ m is formed.
- Protective film (protective film 240): PET sheet having a thickness of 25 ⁇ m
- Copper foil (metal foil 150): thickness of 25 ⁇ m
- a via paste was prepared by blending the metal components of the copper particles and Sn-Bi solder particles described in (Table 1), the epoxy resin and the resin component of the curing agent, and mixing them with a planetary mixer. ing.
- the blending ratio of the resin component is 10 parts by weight of epoxy resin and 2 parts by weight of curing agent with respect to 100 parts by weight of the total of copper particles and Sn—Bi solder particles.
- a protective film is bonded to both surfaces of the resin sheet. Then, 100 holes having a diameter of 150 ⁇ m are drilled by laser from the outside of the resin sheet to which the protective film is bonded.
- the resistance value of 100 via-hole conductors formed on the obtained flexible wiring board is measured by a four-terminal method. Then, 100 initial resistance values and maximum resistance values are obtained. As the initial resistance value, A is 2 m ⁇ or less and B is 2 m ⁇ or more. Further, as the maximum resistance value, A is less than 3 m ⁇ , and B is greater than 3 m ⁇ .
- the initial resistance value (initial average resistance value) is calculated by forming a daisy chain including 100 vias, measuring the total resistance value of 100 vias, and dividing this by 100.
- the maximum resistance value is the maximum value among the average resistance values of the daisy chains formed by forming 100 daisy chains including 100 vias.
- Table 1 the resistance value (m ⁇ ) and the specific resistance value ( ⁇ ⁇ m) are described.
- FIG. 10 shows a triangular diagram of each composition of the examples and comparative examples shown in (Table 1).
- Examples 1 to 17 are indicated by E1 to E17
- Comparative Examples 1 to 9 are indicated by C1 to C9.
- white circle indicates the composition of the example
- black circle indicates the composition of comparative example 1 (C1) in which the Bi amount relative to the Sn amount is smaller than the metal composition of the example.
- “white triangle” is a composition of Comparative Example 7 (C7) in which the Bi amount relative to the Sn amount is larger than the metal composition of the example, and “white square” is a comparison in which the Sn amount relative to the Cu amount is larger than the metal composition of the example.
- Comparative examples 3, 5, and 8 (C3, C5) in which the composition of Examples 2, 4, 6, and 9 (C2, C4, C6, and C9) and “black triangle” are smaller in Sn amount relative to the Cu amount than the metal composition of the example , C8).
- the composition of the example in which A evaluation can be obtained for all the determinations of the initial resistance value, the maximum resistance value, and the connection reliability is as follows. 37: 0.567: 0.063), B (0.22: 0.3276: 0.4524), C (0.79: 0.09: 0.12), D (0.89: 0.10) : 0.01) is a range of a region surrounded by a quadrangle.
- point A indicates Example 2 (E2)
- point B indicates Example 12 (E12)
- point C indicates Example 9 (E9)
- point D indicates Example 13 (E13).
- the weight ratio (Cu: Sn: Bi) in the triangular diagram is changed to C (0.79: 0.09: 0.12), D (0.89: 0.10: 0.01), E ( 0.733: 0.240: 0.027) and F (0.564: 0.183: 0.253) as a region surrounded by a quadrangle, the weight of Cu having a lower resistance value
- the resistance of via holes is reduced.
- all the Cu and Sn are alloyed to eliminate Sn-Bi remelting, thereby realizing a highly reliable flexible wiring board.
- Comparative Example 7 in the region having a composition with a large amount of Bi with respect to the amount of Sn plotted by the “white triangle” in FIG. 10, the amount of bismuth precipitated in the via increases.
- the volume resistivity of Bi is 78 ⁇ ⁇ cm, the volume resistivity of Cu (1.69 ⁇ ⁇ cm), the volume resistivity of Sn (12.8 ⁇ ⁇ cm), and the volume of the compound of Cu and Sn. It is remarkably larger than the resistivity (Cu 3 Sn: 17.5 ⁇ ⁇ cm, Cu 6 Sn 5 : 8.9 ⁇ ⁇ cm). Therefore, in consideration of the volume resistivity of these metal materials, it is expected that the volume resistivity increases as the amount of Bi with respect to the amount of Sn increases. Furthermore, there is a possibility that the resistance value may change or the connection reliability may be lowered depending on the presence state or the dotted state of bismuth.
- Comparative Examples 3, 5, and 8 (C3, C5, and C8) of the regions having a small Sn amount with respect to the Cu amount plotted by the “black triangle” in FIG. Since the number of Sn—Cu compound layers formed to reinforce the surface contact portion between the particles is reduced, the connection reliability is lowered.
- FIG. 11A and FIG. 12A are electron microscopes of a cross section of a via-hole conductor of a flexible multilayer wiring board obtained using the paste according to Example 16 (E16) (copper particles: Sn-28Bi solder weight ratio is 70:30) It is a figure which shows a (SEM) photograph. Moreover, FIG. 11B and FIG. 12B are those schematic diagrams. 11A and 11B are 3000 times, and FIGS. 12A and 12B are 6000 times.
- the via-hole conductor 140 includes a resin portion 200 and a metal portion 190.
- the resin portion 200 is a resin portion containing an epoxy resin.
- the metal portion 190 includes a first metal region 160 mainly composed of copper, a second metal region 170 mainly composed of a tin-copper alloy, and a third metal region 180 mainly composed of bismuth. Yes.
- the size of the second metal region 170 (and also one or more of its volume or weight and cross-sectional area) is larger than the first metal region 160 and larger than the third metal region 180.
- the plurality of wirings 120 are electrically connected via the second metal region 170.
- the first metal region 160 and the third metal region 180 are interspersed in the second metal region 170 without being in contact with each other, so that the alloying reaction (and the intermetallic compound formation reaction) can be performed. It can be performed uniformly without unevenness.
- FIG. 13A and FIG. 14A are views showing SEM photographs of a connection portion between the metal foil 150 and the via-hole conductor 140 in the present embodiment.
- FIG. 13B is a schematic diagram of FIG. 13A.
- FIG. 14B is a schematic diagram of FIG. 14A.
- the surface in contact with the via-hole conductor 140 of the wiring 120 is roughened.
- the contact area between the via-hole conductor 140 and the metal foil 150 can be increased.
- the connection resistance between the via-hole conductor 140 and the metal foil 150 can be reduced, and the adhesion strength (or peel strength) between the via-hole conductor 140 and the metal foil 150 can be increased.
- the interface portion between the metal foil 150 constituting the wiring 120 and the first metal region 160 containing copper as a main component may not be clearly separated. By making this interface portion unclear, the electrical resistance of the interface portion can be reduced.
- the resin portion 200 when the resin portion 200 remains at the interface portion between the via-hole conductor 140 and the metal foil 150, the resin portion 200 is pressed between the irregularities on the interface. Therefore, the resin portion 200 in the interface portion does not affect the electrical characteristics or the adhesion.
- the resin portion 200 remaining between the copper foil and the via-hole conductor 140 may spread on the surface of the copper foil in a planar shape. . For this reason, the electrical characteristics or adhesion at the interface may be affected.
- FIG. 15 is a graph showing an example of an analysis result by X-ray diffraction (XRD) of a via-hole conductor.
- Peak I is Cu (copper).
- Peak II is Bi (bismuth).
- Peak III is tin (Sn).
- Peak IV is the intermetallic compound Cu 3 Sn.
- Peak V is the intermetallic compound Cu 6 Sn 5 .
- FIG. 15 is an evaluation of the influence of the heating temperature (curing temperature) during pressurization on the via-hole conductor, and shows the measurement results at heating temperatures of 25 ° C., 150 ° C., 175 ° C., and 200 ° C.
- the X axis is 2 ⁇ (unit is degree), and the Y axis is intensity (unit is arbitrary).
- the sample used for the measurement produced the pellet which consists of via paste, and changed the processing temperature of this pellet.
- RINT-2000 manufactured by Rigaku Corporation is used for X-ray diffraction.
- the reliability of the via-hole conductor is increased by making the intermetallic compound not Cu 6 Sn 5 but more stable Cu 3 Sn.
- an alloying reaction in which the intermetallic compound is Cu 3 Sn which is more stable than Cu 6 Sn 5 can be performed.
- the thickness of the heat resistant film as the incompressible member 220 is desirably 3 ⁇ m or more and 55 ⁇ m or less, more preferably 50 ⁇ m or less, and further 35 ⁇ m or less. In addition, when the thickness of the heat resistant film is less than 3 ⁇ m, the film strength is lowered and the compression effect of the via paste 260 may not be obtained.
- the copper particles 290 and the solder particles 300 may not be sufficiently compressed.
- the thickness of the thermosetting adhesive layer 210 provided on the surface of the incompressible member 220 is desirably 1 ⁇ m or more and 15 ⁇ m or less on one side. When it is less than 1 ⁇ m, a predetermined adhesion strength may not be obtained. If it exceeds 15 ⁇ m, the compression effect of the via paste 260 may not be obtained. In addition, it is useful that the thickness of the incompressible member 220 is thicker than the thickness of the thermosetting adhesive layer 210 on one side.
- the metal portion occupied in the via-hole conductor 140 In some cases, the volume fraction of 190 can only be increased to about 60 vol% or more and 70 vol% or less.
- the via hole conductor 140 occupies it.
- the volume fraction of the metal part 190 becomes 80 vol% or more and 82 vol% or less.
- the thickness of the incompressible member 220 is 40 ⁇ m (when the thermosetting adhesive layer 210 having a thickness of 10 ⁇ m is formed on both surfaces, the thickness of the electrically insulating substrate 130 is 60 ⁇ m), the metal portion occupied in the via-hole conductor 140 The volume fraction of 190 is 83 vol% or more and 85 vol% or less.
- the metal portion occupying the via-hole conductor 140 The volume fraction of 190 is 89 vol% or more and 91 vol% or less.
- the metal portion occupying the via-hole conductor 140 becomes 87 vol% or more and 95 vol% or less.
- the thickness of the incompressible member 220 is 10 ⁇ m (when the thermosetting adhesive layer 210 having a thickness of 10 ⁇ m is formed on both surfaces, the thickness of the electrically insulating substrate 130 is 30 ⁇ m), the metal portion occupied in the via-hole conductor 140 The volume fraction of 190 becomes 98 vol% or more and 99.5 vol% or less.
- the thickness of the incompressible member 220 is appropriately selected according to the diameter, density, application, etc. of the via-hole conductor 140.
- the volume fraction of the metal portion 190 in the via-hole conductor 140 can be increased by using the roughened metal foil 150.
- the solder particles 300 having a hardness lower than that of the metal foil 150 are pressed against the uneven surface formed on the surface of the metal foil 150 while being deformed. Therefore, the contact property between the surface of the metal foil 150 and the via paste 260 is increased. Since the solder particles 300 are deformed and come into contact with the surface of the metal foil 150 over a wide area, the reactivity between the surface of the metal foil 150 and the solder particles 300 is increased. As a result, the second metal region 170 can be formed on the surface of the metal foil 150 (or the wiring 120).
- the roughening treatment for example, a treatment in which copper particles are deposited on the surface of the metal foil 150 and a Ni layer, a Zn layer, a chromate layer, a silane coupling layer, or the like is further used is used.
- the surface roughness (Rz) of the roughened surface is preferably 5.0 ⁇ m or more and 16.0 ⁇ m or less.
- the surface roughness (Rz) is set to 5 ⁇ m or more and 10 ⁇ m or less to reduce etching residue when the metal foil 150 is removed by etching. Since it is possible, it is more preferable.
- the surface roughness (Rz) of the roughened surface By setting the surface roughness (Rz) of the roughened surface to 5.0 ⁇ m or more and 16.0 ⁇ m or less (more preferably 5 ⁇ m or more and 10 ⁇ m or less), 1.0 to 1.0 before solder reflow and after solder reflow. A peel strength of 2.0 kN / m is obtained.
- JIS C5106 bending resistance test, bending test, insulation resistance, surface withstand voltage, humidity resistance test, chemical resistance, IEC PCT test, JPCA-BM02 There are no problems with coverlay peeling. This is considered because the reliability of the via-hole conductor 140 is high and the connectivity between the via-hole conductor 140 and the metal foil 150 is also high.
- the electrical connectivity between the metal foil 150 and the via-hole conductor 140 is not affected. This is presumably because the silane coupling layer or the like is thin and roughened, and therefore, when the metal foil 150 is strongly pressed against the via paste 260, the silane coupling layer or the like is destroyed. As a result, the metal foil 150 and the copper particles 290 and solder particles 300 in the via paste 260 are in direct contact.
- FIG. 16A is a cross-sectional view of a mounted product using the flexible wiring board in the present embodiment.
- FIG. 16B is a cross-sectional view of a mounted product using the flexible multilayer wiring board in the embodiment of the present invention.
- the mounted product 350 includes a flexible wiring board 600 and a semiconductor 360 shown in FIG. 3C.
- the flexible wiring board 600 and the semiconductor 360 are mounted by a mounting portion 370.
- the mounted product 450 includes the flexible multilayer wiring board 111 and the semiconductor 360 shown in FIG. 4C.
- the flexible multilayer wiring board 111 and the semiconductor 360 are mounted by a mounting portion 370.
- the mounting part 370 is a die bond part or the like made of solder, bumps, wires, or a die bond material.
- the flexible multilayer wiring board 111 may have any number of layers.
- the flexible wiring board 600 or the flexible multilayer wiring board 111 of the present embodiment can be bent even at a portion where the via-hole conductor 140 exists. This is because the metal portion 190 (see FIG. 1B) of the via-hole conductor 140 is firmly bonded to the metal foil 150 (or the wiring 120). Note that the semiconductor 360 can be bent outside the mounting region. By bending outside the mounting area of the semiconductor 360, the influence of the bending stress on the semiconductor 360 and the mounting portion 370 can be reduced.
- FIG. 16B is a cross-sectional view showing a state in which the semiconductor 360 is mounted on the flexible multilayer wiring board 110 having the core layer portion 380 and the buildup layer portion 390.
- the core layer portion 380 has an incompressible member 220 and a core adhesive layer 400 (thermosetting adhesive layer 210) provided on both sides thereof.
- the buildup layer portion 390 includes an incompressible member 220 and a buildup adhesive layer 410 (thermosetting adhesive layer 210) provided on both sides thereof. Further, a part of the build-up adhesive layer 410 embeds the wiring 120 protruding on the surface of the core layer portion 380.
- a flexible multilayer wiring board 111 shown in FIG. 16B is a four-layer board having a core layer portion 380 and a buildup layer portion 390.
- An example of the specifications of the prototyped four-layer flexible multilayer wiring board 111 is shown in Table 2.
- the present application is not limited to the configuration of the four-layer substrate and the specifications of (Table 2). Depending on the market needs, it may be a 6-layer or 8-layer configuration, or a flexible multilayer wiring board 111 with the specifications shown in Table 2 changed.
- the via configuration of the present application it is possible to further increase the number of layers of the flexible multilayer wiring board 111 or to further reduce the diameter of the via.
- a via provided in the core layer portion 380 is a via hole conductor 140. Further, the same results are obtained for the vias provided in the build-up layer portion 390 of the flexible multilayer wiring board 110, both as the via-hole conductor 140 and as a general plated via (blind via).
- thermosetting adhesive layer 210 physical properties of the adhesive used as the thermosetting adhesive layer 210 are shown in (Table 3). However, in (Table 3), the adhesive used for the core adhesive layer 400 and the adhesive used for the build-up adhesive layer 410 are different.
- a viscoelasticity measuring device (DMS) manufactured by SII Nanotechnology Inc. (SII) is used.
- the elastic modulus of the buildup adhesive layer 410 is lower than the elastic modulus of the core adhesive layer 400.
- the elastic modulus of the buildup adhesive layer 410 is more preferably 20% or less, and further preferably 50% or less, of the elastic modulus of the core adhesive layer 400.
- the glass transition temperature of the core adhesive layer 400 is higher than the glass transition temperature of the build-up adhesive layer 410. It is more desirable that the glass transition temperature of the core adhesive layer 400 be higher by 10 ° C. or more by 20 ° C. or more than the glass transition temperature of the build-up adhesive layer 410.
- the flexible wiring board of this embodiment is effective for cost reduction, downsizing, high functionality, and high reliability, and is therefore used for mobile phones and the like.
Abstract
Description
・Sn-Bi系半田粒子(半田粒子300):組成別に(表1)に示す半田組成になるように配合して溶融させたものをアトマイズ法にて粉状化し、平均粒子径5μmに分球したものを使用している。
・エポキシ樹脂(熱硬化性樹脂成分310):ジャパンエポキシレジン(株)製jeR871
・硬化剤:2-メチルアミノエタノール、沸点160℃、日本乳化剤(株)製
・樹脂シート(未硬化基材230):縦500mm×横500mm、厚み10μm~50μmのポリイミドフィルム(非圧縮性部材220)の両表面に厚み10μmの未硬化エポキシ樹脂層(熱硬化性接着層210)が形成されている。
・保護フィルム(保護フィルム240):厚み25μmのPET製シート
・銅箔(金属箔150):厚み25μm
(表1)に記載した配合割合の銅粒子及びSn-Bi系半田粒子の金属成分とエポキシ樹脂及び硬化剤の樹脂成分とを配合し、プラネタリーミキサーで混合することにより、ビアペーストを作製している。なお、樹脂成分の配合割合は、銅粒子及びSn-Bi系半田粒子の合計100重量部に対して、エポキシ樹脂10重量部、硬化剤2重量部としている。
樹脂シートの両表面に保護フィルムを貼り合わせる。そして、保護フィルムを貼り合わせた樹脂シートの外側からレーザーにより直径150μmの孔を100個穿孔する。
〈抵抗値試験〉
得られたフレキシブル配線基板に形成された100個のビアホール導体の抵抗値を4端子法により測定する。そして、100個の初期抵抗値と最大抵抗値を求める。なお、初期抵抗値としては2mΩ以下のものをA、2mΩを超えていたものをBとしている。また、最大抵抗値としては3mΩ未満の場合をA、3mΩより大きい場合をBとしている。
初期抵抗値を測定したフレキシブル配線基板に対して、500サイクルのヒートサイクル試験を行い、初期抵抗値に対する変化率が10%以下のものをA、10%を超えたものをBとしている。
120,120a,120b,121a,121b 配線
130 電気絶縁性基材
140 ビアホール導体
150 金属箔
160 第1金属領域
170 第2金属領域
180 第3金属領域
190 金属部分
200 樹脂部分
210 熱硬化性接着層
220 非圧縮性部材
230 未硬化基材
240 保護フィルム
250 貫通孔
260 ビアペースト
270 突出部
280,280a,280b,280c,280d 矢印
290 銅粒子
300 半田粒子
310 熱硬化性樹脂成分
320 芯材
330 半硬化樹脂
340 圧縮性部材
350 実装製品
360 半導体
370 実装部
380 コア層部分
390 ビルドアップ層部分
400 コア接着層
410 ビルドアップ接着層
450 実装製品
500 基板
600 フレキシブル配線基板
Claims (19)
- 屈曲性を有する非圧縮性部材と屈曲性を有する熱硬化性部材とを有する電気絶縁性基材と、
前記電気絶縁性基材を挟んで形成された第1の配線と第2の配線と、
前記電気絶縁性基材を貫通し、前記第1の配線と前記第2の配線を電気的に接続するビアホール導体と、を有し、
前記ビアホール導体は、樹脂部分と、金属部分とを有し、
前記金属部分は、Cuを主成分とする第1金属領域と、
Sn-Cu合金を主成分とする第2金属領域と、
Biを主成分とする第3金属領域とを有し、
前記第2金属領域は、前記第1金属領域より大きく、かつ前記第3金属領域より大きい
フレキシブル配線基板。 - 前記第2金属領域は、前記第1金属領域と前記第3金属領域を覆っている
請求項1記載のフレキシブル配線基板。 - 前記第1金属領域と前記第3金属領域は、互いに接触することなく存在している
請求項1記載のフレキシブル配線基板。 - 前記第2金属領域はCu6Sn5とCu3Snとを有し、Cu6Sn5/Cu3Snの比が0.001以上、0.100以下である
請求項1記載のフレキシブル配線基板。 - 前記金属部分の中のCu、Sn及びBiの重量組成比Cu:Sn:Biが、三角図において、A(0.37:0.567:0.063)、B(0.22:0.3276:0.4524)、C(0.79:0.09:0.12)、D(0.89:0.10:0.01)を頂点とする四角形で囲まれる領域内にある
請求項1に記載のフレキシブル配線基板。 - 前記ビアホール導体において、前記金属部分は、74.0vol%以上、99.5vol%以下である
請求項1記載のフレキシブル配線基板。 - 前記ビアホール導体において、前記樹脂部分は、0.5vol%以上、26.0vol%以下である
請求項1記載のフレキシブル配線基板。 - 前記ビアホール導体全体に対する、前記第1金属領域と前記第2金属領域との合計の重量割合が20%以上、90%以下である
請求項1に記載のフレキシブル配線基板。 - 前記樹脂部分はエポキシ樹脂の硬化物を有する
請求項1に記載のフレキシブル配線基板。 - 前記ビアホール導体の比抵抗が1.00×10-7Ω・m以上、5.00×10-7Ω・m以下である
請求項1に記載のフレキシブル配線基板。 - 前記非圧縮性部材は、内部に空間を有さないフィルムである
請求項1に記載のフレキシブル配線基板。 - 前記熱硬化性部材は、エポキシ樹脂である
請求項1に記載のフレキシブル配線基板。 - 前記熱硬化性部材の25℃における弾性率は、0.1GPa以上、10.0GPa以下である
請求項1に記載のフレキシブル配線基板。 - 屈曲性を有する第1の非圧縮性部材と屈曲性を有する第1の熱硬化性部材とを有する第1の電気絶縁性基材と、
前記第1の電気絶縁性基材を挟んで形成された第1の配線と第2の配線と、
前記第1の電気絶縁性基材を貫通し、前記第1の配線と前記第2の配線を電気的に接続する第1のビアホール導体と、を有し、
前記第1のビアホール導体は、樹脂部分と、金属部分とを有し、
前記金属部分は、Cuを主成分とする第1金属領域と、
Sn-Cu合金を主成分とする第2金属領域と、
Biを主成分とする第3金属領域とを有し、
前記第2金属領域は、前記第1金属領域より大きく、かつ前記第3金属領域より大きい
コア層部分と、
屈曲性を有する第2の非圧縮性部材と屈曲性を有する第2の熱硬化性部材とを有する第2の電気絶縁性基材と、
前記第2の電気絶縁性基材を貫通する第2のビアホール導体とを有する
ビルドアップ層部分と、
を有し、
前記ビルドアップ層部分は、前記コア層部分に重ねて形成されており、
前記第2の熱硬化性部材の弾性率は、前記第1の熱硬化性部材の弾性率より低い
フレキシブル多層配線基板。 - 屈曲性を有する非圧縮性部材と屈曲性を有する未硬化の熱硬化性部材とを有する基材の両側に保護フィルムを付与するステップと、
前記保護フィルムで被覆された前記基材に、前記保護フィルムの外側から穿孔することにより、貫通孔を形成するステップと、
前記貫通孔に、銅粒子と、錫とビスマスを含有する半田粒子と、樹脂と、を有するビアペーストを充填するステップと、
前記保護フィルムを剥離することにより、前記貫通孔から前記ビアペーストの一部が突出した突出部を形成するステップと、
前記突出部を覆うように、前記基材の表面に金属箔を配置するステップと、
前記金属箔から前記ビアペーストに圧力を加えることにより、前記樹脂の一部を前記基材に流動させるステップと、
前記ビアペーストを加熱することにより前記樹脂を硬化させ、
樹脂部分と、
Cuを主成分とする第1金属領域と、
Sn-Cu合金を主成分とする第2金属領域と、
Biを主成分とする第3金属領域とを有し、
前記第2金属領域が、前記第1金属領域より大きく、かつ前記第3金属領域より大きい、
金属部分と、
を有するビアホール導体を形成すると共に、
前記基材を加熱することにより、前記熱硬化性部材を硬化させる
ステップと、
前記金属箔をパターニングすることにより配線を形成するステップと、
を備えた
フレキシブル配線基板の製造方法。 - 前記非圧縮性部材は、内部に空間を有さないフィルムである
請求項15記載のフレキシブル配線基板の製造方法。 - 前記熱硬化性部材は、エポキシ樹脂である
請求項15に記載のフレキシブル配線基板の製造方法。 - 前記金属箔は粗化処理されており、前記金属箔の表面粗さは、5.0μm以上、16.0μm以下である
請求項15に記載のフレキシブル配線基板の製造方法。 - 屈曲性を有する非圧縮性部材と屈曲性を有する熱硬化性部材とを有する電気絶縁性基材と、
前記電気絶縁性基材を挟んで形成された第1の配線と第2の配線と、
前記電気絶縁性基材を貫通し、前記第1の配線と前記第2の配線を電気的に接続するビアホール導体と、を有し、
前記ビアホール導体は、樹脂部分と、金属部分とを有し、
前記金属部分は、Cuを主成分とする第1金属領域と、
Sn-Cu合金を主成分とする第2金属領域と、
Biを主成分とする第3金属領域とを有し、
前記第2金属領域は、前記第1金属領域より大きく、かつ前記第3金属領域より大きい
フレキシブル配線基板と、
前記フレキシブル配線基板に実装部を介して接続された
半導体と、を有する
実装製品。
Priority Applications (3)
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JP2013521338A JP5333702B1 (ja) | 2011-12-28 | 2012-12-25 | フレキシブル配線基板とその製造方法と、これを用いた実装製品と、フレキシブル多層配線基板 |
US13/990,378 US20140071639A1 (en) | 2011-12-28 | 2012-12-25 | Flexible wiring board, method for manufacturing same, mounted product using same, and flexible multilayer wiring board |
CN2012800121467A CN103416111A (zh) | 2011-12-28 | 2012-12-25 | 挠性线路基板及其制造方法、使用该挠性线路基板的安装产品以及挠性多层线路基板 |
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US (1) | US20140071639A1 (ja) |
JP (1) | JP5333702B1 (ja) |
CN (1) | CN103416111A (ja) |
TW (1) | TW201340807A (ja) |
WO (1) | WO2013099205A1 (ja) |
Families Citing this family (9)
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TWI490115B (zh) | 2014-03-07 | 2015-07-01 | Azotek Co Ltd | 金屬基板及其製作方法 |
WO2016114262A1 (ja) * | 2015-01-13 | 2016-07-21 | 宇部エクシモ 株式会社 | フレキシブル積層板及び多層回路基板 |
JP6538372B2 (ja) * | 2015-02-26 | 2019-07-03 | 東芝ディーエムエス株式会社 | 多層リジッドフレキシブル基板の製造方法 |
US10163801B2 (en) * | 2016-10-14 | 2018-12-25 | Taiwan Semiconductor Manufacturing Co., Ltd. | Structure and formation method of chip package with fan-out structure |
CN109389903B (zh) | 2017-08-04 | 2021-01-29 | 京东方科技集团股份有限公司 | 柔性基板及其加工方法、加工系统 |
JP7426587B2 (ja) * | 2017-09-04 | 2024-02-02 | パナソニックIpマネジメント株式会社 | 伸縮性回路基板、及び、それを用いたパッチデバイス |
US11581239B2 (en) | 2019-01-18 | 2023-02-14 | Indium Corporation | Lead-free solder paste as thermal interface material |
CN112349676B (zh) | 2019-08-06 | 2022-04-05 | 奥特斯奥地利科技与系统技术有限公司 | 半柔性的部件承载件及其制造方法 |
US11602046B2 (en) * | 2020-05-28 | 2023-03-07 | Kyocera Corporation | Wiring board |
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- 2012-12-25 JP JP2013521338A patent/JP5333702B1/ja not_active Expired - Fee Related
- 2012-12-25 US US13/990,378 patent/US20140071639A1/en not_active Abandoned
- 2012-12-25 WO PCT/JP2012/008235 patent/WO2013099205A1/ja active Application Filing
- 2012-12-25 CN CN2012800121467A patent/CN103416111A/zh active Pending
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JP2006287019A (ja) * | 2005-04-01 | 2006-10-19 | Hitachi Metals Ltd | 貫通電極付基板およびその製造方法 |
JP2011243947A (ja) * | 2010-01-05 | 2011-12-01 | Panasonic Corp | 多層基板とその製造方法 |
JP2011176220A (ja) * | 2010-02-25 | 2011-09-08 | Panasonic Corp | 配線基板、配線基板の製造方法、及びビアペースト |
JP2011199250A (ja) * | 2010-02-25 | 2011-10-06 | Panasonic Corp | 多層配線基板、及び多層配線基板の製造方法 |
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JPWO2013099205A1 (ja) | 2015-04-30 |
CN103416111A (zh) | 2013-11-27 |
US20140071639A1 (en) | 2014-03-13 |
TW201340807A (zh) | 2013-10-01 |
JP5333702B1 (ja) | 2013-11-06 |
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