JP2014049646A - Part mounting method and part mounting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable formation of a solder-joint portion having a sufficient re-fusion temperature and prevention of short-circuiting of adjacent electrodes even when an electrical part and an electrode of a circuit board are joined to each other under thermal press-fitting by using solder having a relatively low melting point.SOLUTION: A part mounting method comprises a step for preparing a first target having plural first electrodes, a step for preparing a second target as an electrical part having plural second electrodes, a step for supplying the first electrodes with resin-solder mixture containing granular material and thermosetting resin, the granular material containing a core containing first metal and a solder layer containing second metal having a lower melting point than the first metal, a step for mounting the second target on the first target, a step for thermally press-fitting the plural second electrodes and the corresponding first electrodes to form a joint portion containing the first metal and the second metal, and a step for heating the joint portion to promote generation of intermetallic compounds at the joint portion through mutual diffusion between the first metal and the second metal and curing the thermosetting resin.

Description

  The present invention relates to a component mounting method and a component mounting system. More specifically, the present invention relates to a component mounting method and a component mounting system for mounting various electronic components on a substrate such as a circuit board of an electronic device.

  2. Description of the Related Art Conventionally, in a component mounting structure configured by connecting an electronic component such as a semiconductor chip to a substrate such as a circuit board, the electronic component and the circuit board are electrically and mechanically bonded by soldering each electrode. Connected. However, solder bonding is mainly intended for electrical connection between electrodes, and the mechanical bonding strength is smaller than that of, for example, welding. For this reason, a resin reinforcing part is formed by providing an adhesive containing a thermosetting resin between the electronic component and the circuit board, thereby reinforcing the solder joint part.

  In such a case, a solder powder mixed in an adhesive, for example, a paste (hereinafter referred to as a solder-resin mixture) is supplied between the corresponding electrodes of the electronic component and the circuit board. (For example, refer to Patent Document 1). This makes it possible to simultaneously perform solder bonding between the electrodes and resin reinforcement of the solder bonding portion with an adhesive. Here, in Patent Document 1, by setting the melting temperature of the solder powder to a temperature lower than the glass transition temperature of the thermosetting resin contained in the adhesive, the resin reinforcing portion, the electronic component, or the circuit board The thermal stress acting between the joint surfaces of the two is suppressed.

  However, as described in Patent Document 1, when solder having a relatively low melting point is used for joining electrode terminals, soldering is performed when a reheating process such as a reflow process is further performed after the electronic component is joined to the circuit board. The joint becomes easy to remelt. Thereby, the connection reliability between an electronic component and a circuit board may fall.

  In order to avoid this, in Patent Document 2, an intermetallic compound of solder and Cu is generated by mixing high melting point metal particles such as Cu particles into the above-described solder-resin mixture, and thereby solder bonding. It is proposed to increase the remelting temperature of the part.

JP 2008-69316 A JP 2002-261105 A

  However, in order to sufficiently increase the remelting temperature of the solder joint portion by generating the intermetallic compound of solder and Cu as described above, a relatively large amount is required to increase the contact area between the Cu particles and the solder. It is necessary to include Cu particles in the solder-resin mixture.

  As shown in FIG. 17, when the electrode 16A of the electronic component 12A and the electrode 18A of the corresponding circuit board 14A are joined by thermocompression bonding, the electronic component and the circuit board are brought into contact with each other so that the corresponding electrodes are brought into contact with each other. Are pressed against each other with a predetermined pressure. Therefore, in solder joining by thermocompression bonding, a space for accommodating the molten solder 49 in which the solder 48 is melted is reduced between the electrodes. For this reason, when the Cu particles 46 are included in the solder-resin mixture, the molten solder 49 overflowing from the space between the electrodes may travel along the Cu particles 46 and spread to the adjacent electrodes. As a result, when the distance between adjacent electrodes is small, a short circuit occurs between the electrodes, and the connection reliability between the electronic component and the circuit board decreases.

  Therefore, the present invention can form a joint portion having a sufficiently high remelting temperature even when the electrodes of the electronic component and the circuit board are joined by thermocompression bonding using a solder having a relatively low melting point. An object of the present invention is to provide an electronic component mounting method and an electronic component mounting system capable of preventing a short circuit between adjacent electrodes and improving the connection reliability between the electronic component and the circuit board. Yes.

The component mounting method of the present invention includes a step of preparing a first object having a plurality of first electrodes,
Preparing a second object as an electronic component having a plurality of second electrodes corresponding to the plurality of first electrodes;
A solder layer including a granular material and a thermosetting resin, wherein the granular material covers a core including a first metal, and a second metal having a melting point lower than that of the first metal. And supplying the first electrode with a resin-solder mixture in which the first metal is in contact with the solder layer and the first metal and the second metal can form an intermetallic compound. Process,
Mounting the second object on the first object such that the plurality of second electrodes respectively land on the corresponding first electrode via the solder-resin mixture;
Thermocompression bonding the plurality of second electrodes and the corresponding first electrode to form a joint including the first metal and the second metal, and heating the joint, A step of accelerating the formation of an intermetallic compound by mutual diffusion of the first metal and the second metal at the joint, and curing the thermosetting resin;
including.

The component mounting system of the present invention includes a holding unit that holds a first object having a plurality of first electrodes,
Including a granular material and a thermosetting resin, wherein the granular material includes a core including a first metal, and a solder layer covering a surface of the core and including a second metal having a lower melting point than the first metal, A mixture supply unit that supplies the first electrode with a solder-resin mixture in which the first metal is in contact with the solder layer and the first metal and the second metal can form an intermetallic compound. When,
The second object as an electronic component having a plurality of second electrodes corresponding to the plurality of first electrodes is held, and the solder-resin mixture to the first electrode corresponding to each of the plurality of second electrodes. A mounting unit for mounting the second object on the first object so as to land via
While the mounting unit presses the second object toward the first object and heats the second object, the plurality of second electrodes and the corresponding first electrode By thermocompression bonding, a joint portion including the first metal and the second metal is formed, and the joint portion is further heated, thereby causing mutual diffusion of the first metal and the second metal at the joint portion. The formation of intermetallic compounds is promoted and the thermosetting resin is cured.

Furthermore, the component mounting system of the present invention includes a holding unit that holds a first object having a plurality of first electrodes,
Including a granular material and a thermosetting resin, wherein the granular material includes a core including a first metal, and a solder layer covering a surface of the core and including a second metal having a lower melting point than the first metal, A mixture supply unit that supplies the first electrode with a solder-resin mixture in which the first metal is in contact with the solder layer and the first metal and the second metal can form an intermetallic compound. When,
The second object as an electronic component having a plurality of second electrodes corresponding to the plurality of first electrodes is held, and the solder-resin mixture to the first electrode corresponding to each of the plurality of second electrodes. The second object is mounted on the first object so as to land via the first object, the second object is pressed toward the first object, and the second object is heated. By mounting the plurality of second electrodes and the corresponding first electrode by thermocompression bonding, a mounting unit that forms a joint including the first metal and the second metal,
By further heating the joint in a state where the second object mounted on the first object is stored or held, the first metal and the second metal are interdiffused at the joint. And a post-heating unit that accelerates generation of the intermetallic compound and cures the thermosetting resin.

  According to the present invention, it is possible to form a joint portion having a sufficiently high remelting temperature even when the electronic component and the circuit board electrodes are joined to each other by thermocompression bonding using a solder having a relatively low melting point. In addition, the adjacent electrodes can be prevented from being short-circuited, and the connection reliability between the electronic component and the circuit board can be improved.

1 is a block diagram showing a schematic configuration of a component mounting system according to an embodiment of the present invention. It is sectional drawing which shows an example of the component mounting structure manufactured by the component mounting system and component mounting method of this invention. It is a partial cross section figure which shows the state just before performing a thermocompression-bonding process in a thermocompression-bonding / heating unit or a thermocompression-bonding unit. It is sectional drawing which shows the structure of the granular material contained in a solder-resin mixture. It is a partial cross section figure which shows the state by which the solder-resin mixture was supplied to the board | substrate electrode in the mixture supply unit. It is a partial cross section figure which shows the state which started the thermocompression bonding process in the thermocompression bonding / heating unit or the thermocompression bonding unit. FIG. 7 is a partial cross-sectional view in which a main part of FIG. 6 is enlarged.

FIG. 8 is a partial cross-sectional view showing a state where a solder layer is melted after the state of FIG. 7. FIG. 9 is a partial cross-sectional view illustrating a state in which an intermetallic compound is generated after the state of FIG. 8. FIG. 10 is a partial cross-sectional view illustrating a state in which the molten solder is solidified and the formation of the joint portion is completed after the state of FIG. 9. It is a partial cross section figure which shows the state of the other part of the resin reinforcement part in the state of FIG. 10A. It is a partial cross section figure of the principal part of the component mounting structure manufactured by the component mounting system and component mounting method which concern on other embodiment of this invention. It is sectional drawing which shows the structure of the granular material contained in the solder-resin mixture used for manufacture of the component mounting structure of FIG. 11A. It is the partial cross section figure which expanded the principal part of the component mounting structure manufactured by the component mounting system and component mounting method which concern on further another embodiment of this invention. FIG. 13 is an enlarged partial cross-sectional view of a part of a conventional part mounting structure corresponding to the part mounting structure of FIG. It is a block diagram which shows schematic structure of the component mounting system which concerns on further another embodiment of this invention.

It is a partial cross section figure which shows an example of the post-heating unit of the component mounting system of FIG. FIG. 15 is a partial cross-sectional view illustrating another example of the post-heating unit of the component mounting system in FIG. 14. It is a partial cross section figure which expands and shows a part of conventional component mounting structure for demonstrating the problem of the conventional component mounting structure manufactured by the conventional component mounting system and the component mounting method. It is a partial cross section figure which expands and shows a part of conventional component mounting structure for explaining other problems of the conventional component mounting structure manufactured by the conventional component mounting system and component mounting method. .

  The present invention provides a step of preparing a first object having a plurality of first electrodes, a step of preparing a second object as an electronic component having a plurality of second electrodes corresponding to the plurality of first electrodes, Including a granular material and a thermosetting resin, wherein the granular material includes a core including a first metal, and a solder layer that covers the surface of the core and includes a second metal having a lower melting point than the first metal, Supplying a solder-resin mixture in which the first metal is in contact with the solder layer and the first metal and the second metal can form an intermetallic compound to the first electrode; The step of mounting on the first object such that the plurality of second electrodes land on the corresponding first electrodes via the solder-resin mixture, and the plurality of second electrodes and the corresponding first electrodes are thermocompression bonded. And forming the joint including the first metal and the second metal, and heating the joint It allows along with promoting the formation of intermetallic compounds by mutual diffusion between the first metal and the second metal at the junction, curing the thermosetting resin. Here, the electronic component includes, for example, various electronic components such as an IC chip (bare chip), a package, an electronic component module, and a chip component. The solder-resin mixture may be pasty, semi-cured (B stage), and film.

  As described above, in the present invention, the granular material contained in the solder-resin mixture has a core containing the first metal that comes into contact with the solder layer, and the second metal (solder, Alternatively, a solder layer containing a solder alloy) is formed. As a result, the contact area between the first metal and the second metal can be increased, and the amount of intermetallic compound produced between the first metal having a relatively high melting point and the second metal at the joint is increased. Can do. Thereby, it becomes easy to make the remelting temperature of a junction part higher than melting | fusing point of the original 2nd metal, and the connection reliability of an electronic component and a board | substrate can be improved.

  As a result of the above, for example, as shown in FIG. 17, compared to the case where the first metal particles (46) are simply included in the solder-resin mixture, a sufficient amount of intermetallic compound is produced to produce the joint portion. The content of the first metal particles required for raising the remelting temperature to a desired temperature can be reduced. As a result, it is possible to prevent the molten solder (49) overflowing from the space between the corresponding electrodes from being transmitted through the first metal particles (46) present in large quantities and spreading out between the adjacent electrodes. it can. Therefore, it is possible to prevent a short circuit from occurring between adjacent electrodes, and to improve the connection reliability between the electronic component and the substrate.

  Furthermore, since the solder is also supplied in a state of being included in the solder layer on the surface of the granular material, it is easy to suppress the supply amount to a necessary and sufficient amount. And since the core of a granular material contains the 1st metal with comparatively high melting | fusing point, a corresponding | compatible electrode is mutually thermocompression bonded, maintaining the original shape of the core of the granular material pinched | interposed. As a result, since the corresponding electrodes are thermocompression bonded to each other with a certain gap secured, it is possible to suppress the amount of molten solder overflowing from the space between the corresponding electrodes. Therefore, it is possible to more effectively prevent a short circuit from occurring between adjacent electrodes.

  In another embodiment of the present invention, the core includes resin particles, and the first metal is interposed between the resin particles and the solder layer. By including the resin particles in the core, the core can be made difficult to be crushed when the corresponding electrodes are thermocompression bonded to each other. Thereby, it becomes easy to secure a desired gap between corresponding electrodes, and for example, it becomes easy to secure a transmission line length of a signal as designed. In addition, this form includes the case where the resin particle is in the center of the core and the entire surface of the resin particle is covered with the first metal layer. Accordingly, even if the content of the first metal is reduced, the contact area between the first metal and the solder layer can be maximized, and the remelting temperature of the joint can be sufficiently increased. Moreover, cost can be reduced by using an inexpensive material for the resin particles. It is not essential that the entire surface of the resin particle is covered with the first metal layer, and a part of the surface of the resin particle may be in direct contact with the solder layer.

  The average particle size (particle size at 50% cumulative volume in the volume particle size distribution, hereinafter the same) is preferably 2 to 100 μm and the thickness of the solder layer is 0.1 to 10 μm. preferable. If the average particle diameter of the granular material and the thickness of the solder layer are in this range, the solder layer is relatively thin, so it is easy to make almost all of the solder contained in the joint part an intermetallic compound. It becomes. As a result, it becomes easy to sufficiently raise the remelting temperature of the joint. In addition, it is easy to secure a gap of a certain amount or more between the corresponding electrodes, and the supply amount of solder is suppressed, so that it is possible to more effectively prevent a short circuit from occurring between adjacent electrodes.

  Furthermore, the content of the particulate matter in the solder-resin mixture is preferably set in the range of 0.1 to 10% by volume. By setting the lower limit of the content of the granular material to 0.1% by volume, the occurrence of poor conduction can be suppressed. On the other hand, the short circuit between adjacent electrodes can be effectively suppressed by setting the upper limit of the content of the granular material to 10% by volume. A more preferable range of the content of the granular material is 0.1 to 5% by volume.

  Here, the first metal preferably contains Cu. That is, the first metal may be a Cu alloy, and its melting point is preferably 1000 ° C. or higher. On the other hand, the second metal is an alloy that forms solder, and preferably contains at least one selected from the group consisting of Sn, Pb, Ag, Zn, Bi, In, Cu, and Sb. The melting point of the second metal is preferably 110 to 240 ° C. The heating temperature during thermocompression bonding is preferably 60 to 250 ° C. A more preferable heating temperature at the time of thermocompression bonding is 120 to 250 ° C.

In another embodiment of the present invention, the solder-resin mixture further contains an inorganic filler such as silica (SiO ₂ ) and alumina having an average particle diameter smaller than that of the granular material. By including an inorganic filler in the solder-resin mixture, a resin reinforcing portion including the inorganic filler can be formed. Thereby, while the thermal expansion coefficient of the resin reinforcing part can be reduced, the elastic modulus can be increased. As a result, even when a heat cycle that heats and cools the component mounting structure is applied to the component mounting structure, or when an impact caused by dropping of an electronic component is applied to the resin reinforcing portion, It is possible to suppress deterioration of the resin reinforcing part such as cracks. Therefore, it is possible to improve the resistance to the heat cycle and impact resistance of the joint. Moreover, since the moisture absorption rate of the resin reinforcing portion can be lowered, it is possible to prevent the electrodes and wiring from being corroded.

  The present invention also includes a holding unit for holding a first object having a plurality of first electrodes, a granular material and a thermosetting resin, wherein the granular material includes a core including a first metal, and a surface of the core. And a solder layer including a second metal having a melting point lower than that of the first metal, the first metal is in contact with the solder layer, and the first metal and the second metal can form an intermetallic compound. A mixture supply unit for supplying a certain solder-resin mixture to the first electrode, a plurality of second electrodes corresponding to the plurality of first electrodes, and holding a second object as an electronic component, The present invention relates to a component mounting system including a mounting unit that mounts a second object on the first object such that the two electrodes land on the corresponding first electrode via a solder-resin mixture. Here, the mounting unit presses the second object toward the first object and heat-compresses the second object and the corresponding first electrode by heating the second object. Forming a joint portion including the first metal and the second metal and further heating the joint portion to promote the formation of an intermetallic compound by mutual diffusion of the first metal and the second metal at the joint portion. And the thermosetting resin is cured.

  Furthermore, the present invention includes a holding unit for holding a first object having a plurality of first electrodes, a granular material and a thermosetting resin, wherein the granular material includes a first metal, and a surface of the core. And a solder layer containing a second metal having a melting point lower than that of the first metal, the first metal is in contact with the solder layer, and the first metal and the second metal can form an intermetallic compound. Holding a second object as an electronic component having a mixture supply unit for supplying the solder-resin mixture to the first electrode, and a plurality of second electrodes corresponding to the plurality of first electrodes, The second object is mounted on the first object so that the second electrode lands on the corresponding first electrode via the solder-resin mixture, and the second object is pressed toward the first object. A plurality of second electrodes by heating the second object, In a state in which the mounting unit that forms the joint including the first metal and the second metal by thermocompression bonding with the corresponding first electrode and the second object mounted on the first object is stored or held, A component mounting including a post-heating unit that further heats the joint and promotes the formation of an intermetallic compound by mutual diffusion between the first metal and the second metal at the joint and cures the thermosetting resin. About the system.

  Here, the post-heating unit includes an oven including a joint portion, a housing portion that houses a precursor of a component mounting structure including the first object and the second object, and a heater that heats the joint portion. It is preferable to include. Or it is preferable that a post-heating unit contains the press machine which has a press stand which touches a 1st target object, and a press plate which touches a 2nd target object. At this time, at least one of the press table and the press plate includes a heater that heats the joint.

(Embodiment 1)
FIG. 1 is a block diagram showing a mounting line as an example of an electronic component mounting system according to an embodiment of the present invention. FIG. 2 is a sectional view showing a component mounting structure manufactured by the component mounting system of the present invention.

  The electronic component mounting system of the present invention is a system for mounting an electronic component (second object) on a board (an example of a first object) such as a circuit board of an electronic device. The substrate may be a rigid substrate or a flexible substrate. Regardless of whether the substrate is a rigid substrate or a flexible substrate, each substrate of each unit of the line 10 can be individually or individually integrated. Can be transported between. For example, when the substrate is a flexible substrate, each substrate is transported between the units of the line 10 by placing them individually on, for example, a carrier board or with a tape-shaped material including a plurality of substrates. can do. A tape-shaped material including a plurality of substrates can be transported between the units of the line 10 by using, for example, a sprocket.

  On the other hand, the electronic component may be a semiconductor chip (bare chip), or a package or module in which a semiconductor chip or the like is mounted on a flexible or rigid substrate. Further, the electronic component may be a chip component such as a passive element.

  The line 10 in the illustrated example is a mounting line for mounting an electronic component 12 that is a module in which a semiconductor chip or the like is mounted on a flexible board on a rigid or flexible board 14 that is a circuit board of an electronic device. More specifically, the line 10 includes a substrate supply unit 1, a mixture supply unit 2, a thermocompression bonding / heating unit 3 including an electronic component supply device 6, and a structure recovery unit 4.

  The substrate supply unit 1 supplies the substrate 14 to the line. The mixture supply unit 2 supplies the solder-resin mixture to the land electrode 18 that is an electrode of the substrate 14. The thermocompression bonding / heating unit 3 is bonded to the plurality of component electrodes 16 of the electronic component 12 supplied by the electronic component supply device 6 and the corresponding plurality of land electrodes 18 of the substrate 14 by thermocompression bonding. 17 is formed (thermocompression treatment) and the joint portion 17 is heated (melting point shift promotion treatment) for the purpose of promoting an increase in the remelting temperature of the joint portion 17, thereby simultaneously reinforcing the joint portion 17. Thus, the resin reinforcing part 29 is formed (resin curing process). The structure recovery unit 4 recovers a component mounting structure in which the electronic component 12 is mounted on the substrate 14.

  In a specific apparatus, the mixture supply unit 2 and the thermocompression bonding / heating unit 3 can be integrated as a device bonder (die bonder or flip chip bonder) 5. The line 10 is provided with a conveyor 8 for transporting the substrate 14 between the units.

  The line 10 may be a surface-mounting line of a carrier transport system in which the substrate 14 is placed on a carrier board and transported between the units by the conveyor 8. The substrate 14 can be fixed to the carrier board with heat-resistant tape. Alternatively, the substrate 14 can be fixed by applying a slightly adhesive type adhesive material to the surface of the carrier board facing the substrate 14. In this case, since the entire back surface of the substrate 14 is fixed to the carrier board, even when the substrate 14 is a flexible substrate, variations in height due to the waviness of the substrate 14 can be reduced. In addition, if it is a rigid board | substrate, the board | substrate 14 can also be directly mounted in the conveyor 8 without using a carrier board.

  For example, a magazine-type substrate loader can be used for the substrate supply unit 1, and a magazine-type substrate unloader can be used for the structure recovery unit 4, for example. When a plurality of substrates 14 are included in the tape-shaped material, the substrate supply unit 1 can include an unwinding roll, and the structure recovery unit 4 can include a winding roll. Can do.

  For example, if the solder-resin mixture is pasty, the mixture supply unit 2 applies a solder-resin mixture to the plurality of land electrodes 18 of the substrate 14 via a nozzle or the like and supplies the application head (not shown). A dispenser that supplies the solder-resin mixture to the coating head, a substrate recognition camera, and a control device. The control device controls the movement and operation of the application head and the operation of the dispenser. In addition, the control device can include an image processing device that processes a captured image of the board recognition camera. Alternatively, the mixture supply unit 2 can include a screen printing device, an inkjet coating device, and the like instead of the coating head. With these printing apparatuses, the solder-resin mixture can be supplied to the plurality of land electrodes 18 of the substrate 14.

  When the solder-resin mixture is formed into a film, the solder-resin mixture is picked up from the separator (release paper) with an adsorption nozzle or the like, or the solder-resin mixture is mounted on the substrate from the separator by thermocompression bonding. Transferred to the area AR1 (see FIG. 5), the solder-resin mixture can be supplied to the plurality of land electrodes 18 of the substrate 14. When the solder-resin mixture is a B stage described later, a solution obtained by dissolving the solder-resin mixture in a solvent is printed or applied in advance on the mounting area AR1, and then heat-treated, whereby the solder-resin mixture is printed on the substrate. Fourteen land electrodes 18 can be supplied.

  The electronic component supply device 6 can include a tape feeder, a bulk feeder, a tray feeder, and the like. At this time, if the electronic component 12 is a module or an LGA package, the electronic component 12 can be supplied by a tray feeder. Alternatively, if the electronic component is a chip component, it can be supplied by a tape feeder or a bulk feeder.

  As shown in FIG. 3, the thermocompression bonding / heating unit 3 includes, for example, a thermocompression bonding head 20 that holds an electronic component 12 by suction, a press stand 24 on which a substrate 14 is placed, and a component electrode 16. A component recognition camera that is not used and a control device (not shown) that controls the movement and operation of the thermocompression bonding head 20 can be included. The thermocompression bonding head 20 can include a heater 22 for heating the component electrode 16. The press table 24 can also include a heater 27 for heating the land electrode 18.

  Next, the solder-resin mixture will be described with reference to FIG. As shown in FIG. 3, the solder-resin mixture 26 is obtained by mixing and dispersing a granular material 30 containing solder in an adhesive 28 containing a thermosetting resin at a predetermined ratio. The solder-resin mixture 26 may be in a paste form or may be formed in a film form. Alternatively, the solder-resin mixture 26 may be a B stage. The B stage refers to an intermediate stage of the reaction of the thermosetting resin.

  The adhesive 28 can be prepared by mixing a thermosetting resin with a curing agent, a thixotropic agent, a pigment, a coupling agent, and an activator. Although the glass transition point of the hardened | cured material of a thermosetting resin is not specifically limited, It is preferable to set it as more than melting | fusing point (for example, 120-160 degreeC) of the solder contained in the granular material 30. FIG. As the activator, a material such as an organic acid or a halide having an active action of removing oxides and the like present on the electrode surface and the bump surface during solder bonding can be used.

  The thermosetting resin to be included in the adhesive 28 is not particularly limited, but there are various types such as an epoxy resin, a urethane resin, an acrylic resin, a polyimide resin, a polyamide resin, a bismaleimide, a phenol resin, a polyester resin, a silicone resin, and an oxetane resin. Resin can be included. These may be used alone or in combination of two or more. Among these, an epoxy resin is particularly preferable from the viewpoint of excellent heat resistance.

  As the epoxy resin, an epoxy resin selected from the group of bisphenol type epoxy resin, polyfunctional epoxy resin, flexible epoxy resin, brominated epoxy resin, glycidyl ester type epoxy resin and polymer type epoxy resin can also be used. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, phenol novolac type epoxy resin, cresol novolak type epoxy resin, etc. are preferably used. Epoxy resins obtained by modifying these are also used. These may be used alone or in combination of two or more.

  As the curing agent used in combination with the thermosetting resin as described above, a compound selected from the group of thiol compounds, modified amine compounds, polyfunctional phenol compounds, imidazole compounds, and acid anhydride compounds is used. be able to. These may be used alone or in combination of two or more.

  Specific examples of solder (second metal) included in the granular material 30 include Sn—Bi alloy, Sn—Ag—Cu alloy, Sn—Bi—Ag alloy, Sn—Cu alloy, Sn—Sb alloy, Sn—Ag. Alloy, Sn-Ag-Cu-Bi alloy, Sn-Ag-Bi-In alloy, Sn-Ag-Cu-Sb alloy, Sn-Zn alloy, Sn-Zn-Bi alloy, etc., but are particularly limited. It is not a thing. For example, gold solder may be used in addition to the above-described solder using Sn as a base material. However, the melting point of the solder contained in the granular material 30 is preferably 110 to 240 ° C.

  FIG. 4 is a sectional view showing an example of the granular material. The granular material 30 in the illustrated example covers a spherical core 32 formed of a first metal (for example, Cu or Cu alloy) having a relatively high melting point (for example, 1000 ° C. or more), and covers the surface of the core 32. And a formed solder layer 34 containing a second metal (solder or solder alloy).

Next, a method for manufacturing the component mounting structure shown in FIG. 2 will be described.
First, as shown in FIG. 5, a mounting region that is a region where the electronic component 12 of the substrate 14 is mounted by the mixture supply unit 2 on the substrate 14 supplied by the substrate supply unit 1. Supply to AR1. In the mounting area AR1, all the land electrodes 18 joined to the component electrodes 16 of the electronic component 12 are formed.

  Next, as shown in FIG. 3, in the thermocompression bonding / heating unit 3, the electronic component 12 supplied by the electronic component supply device 6 is held by the thermocompression bonding head 20. The thermocompression-bonding head 20 can be provided with a plurality of suction nozzles or component suction holes at portions that contact the electronic component 12.

  Then, as shown in FIG. 6, alignment is performed using the captured image of the component recognition camera so that the plurality of component electrodes 16 of the electronic component 12 land on the corresponding land electrodes 18. Then, while heating the electronic component 12 to a predetermined temperature Ta (60 ° C. ≦ Ta ≦ 250 ° C.) by the heater 22 provided in the thermocompression bonding head 20, the electronic component 12 is pressed toward the substrate 14 by the thermocompression bonding head 20. Press with.

  Thereby, as shown in FIG. 7, the granular material 30 is sandwiched between the plurality of component electrodes 16 and the corresponding land electrodes 18. In the figure, the granular materials 30 are sandwiched between the set of component electrodes 16 and the land electrodes 18 one by one. However, the present invention is not limited to this. And the land electrode 18.

  7 is maintained for a predetermined time Ma (for example, 5 seconds), the second metal (solder) contained in the solder layer 34 is melted as shown in FIG. It becomes. The molten solder 36 wets and spreads on the surfaces of the component electrode 16 and the land electrode 18 by the action of removing the oxide film of the activator contained in the adhesive 28, and the molten solder 36 becomes elliptical.

  From the state of FIG. 8, the heating at the predetermined temperature Tb (300 ° C. ≧ Tb ≧ 100 ° C.) in the thermocompression bonding / heating unit 3 is continued for a predetermined time Mb (600 seconds ≧ Mb ≧ 1 seconds). As shown in FIG. 9, the first metal (Cu) contained in the core 32 diffuses into the molten solder 36, and the intermetallic compound layer 38 containing a solid-state intermetallic compound having a melting point higher than that of the original solder is the core. It is generated around 32 (melting point shift promoting process).

  At the same time, the thermosetting resin contained in the adhesive 28 is cured by heating, and the resin reinforcing portion 29 is formed. When the component electrode 16 and the land electrode 18 contain Cu or Cu alloy, Cu contained in these electrodes also diffuses into the molten solder 36. For this reason, as shown in FIG. 9, the thickness of the intermetallic compound layer 38 is larger in the portion close to the component electrode 16 and the land electrode 18 than in the far portion.

  Thereafter, by allowing to cool, as shown in FIG. 10A, the molten solder 36 is solidified to become a solidified solder 40, and the joint portion 17 is completed. In addition, by making all the molten solder 36 into the intermetallic compound layer 38 with Cu, it is possible to more effectively suppress the solder from being melted from the joint portion 17 when the component mounting structure is reheated. . In this case, only the intermetallic compound layer 38 exists around the core 32, and the solidified solder 40 layer does not exist.

  Further, as shown in FIG. 10B, in the portion (second portion 29 a) that is not sandwiched between the corresponding electrodes of the resin reinforcing portion 29, the intermetallic compound layer 38 including the intermetallic compound layer 38 is heated by heating the granular material 30. A compound layer-containing granular material 31 is formed. On the other hand, in the 1st part 29b which exists in the space between corresponding electrodes of the resin reinforcement part 29, the junction part 17 is formed as mentioned above. The intermetallic compound layer-containing granular material 31 includes a core 32 containing a first metal, an intermetallic compound layer 38 of a first metal and a second metal, and a solder layer made of solidified solder 40. In the intermetallic compound layer-containing granular material 31, the solidified solder 40 may be all the intermetallic compound layer 38 and may not have the solidified solder 40.

  As described above, in the first embodiment, the solder-resin mixture 26 including the granular material 30 in which the solder layer 34 is provided on the surface of the spherical core 32 mostly made of Cu and the adhesive 28 is used as the substrate. 14 land electrodes 18 and the component electrodes 16 and the land electrodes 18 are joined by thermocompression bonding. As a result, since the contact area between the solder and Cu is increased, an intermetallic compound between the solder and Cu is easily generated. Therefore, even if the Cu content of the solder-resin mixture 26 is reduced, it is possible to generate a sufficient amount of intermetallic compound, and it is easy to raise the remelting temperature of the joint 17 to a desired temperature. Become. Thereby, Cu particles etc. contained in a large amount in the solder-resin mixture 26 can be transmitted, so that the molten solder can be prevented from spreading to adjacent electrodes, and a short circuit between the electrodes can be prevented.

  Furthermore, as shown in FIG. 10A and FIG. 10B, when the solidified solder 40 is present, the joint 17 has a multilayer structure, and therefore, external stress such as an impact due to the drop of the electronic device is caused between the layers. It is easy to be distributed with. As a result, the joint 17 is not easily destroyed. Further, external stress is easily dispersed only in the solidified solder 40 which is the outermost layer, and even if a crack is generated in the layer, for example, the crack remains only in the solidified solder 40, and the intermetallic compound layer It is difficult to reach 38. Therefore, it becomes easy to ensure the electrical and mechanical connectivity of the joint portion 17. On the other hand, when the solidified solder 40 does not exist in the joint portion 17, the joint portion 17 includes only the first metal core 32 and the intermetallic compound layer 38. As a result, the remelting temperature of the entire joint 17 can be increased.

  On the other hand, as shown in FIG. 18, in the conventional solder joint portion 72 having a single composition only of solder, for example, when one portion of the solder joint portion 72 is broken by an external stress, that portion As a starting point, as shown by an arrow in the figure, the entire solder joint 72 having the same quality is cracked and the solder joint 72 is broken. On the other hand, in the component mounting structure of the first embodiment, as described above, high impact resistance can be obtained and high connection reliability can be ensured. Furthermore, it can prevent that a short circuit generate | occur | produces between adjacent electrodes by making content of the granular material 30 in the solder-resin mixture 26 into a predetermined amount.

Next, Embodiment 2 of the present invention will be described.
(Embodiment 2)
FIG. 11A is a partial cross-sectional view showing a component mounting structure manufactured by the component mounting method according to the present embodiment. FIG. 11B is a sectional view showing a granular material precursor used for manufacturing the component mounting structure according to the present embodiment.

  The granular material 30A of the illustrated example is similar to the granular material 30 of the first embodiment in that it includes a core 32A and a solder layer 34A that covers the surface of the core 32A. However, in the granular material 30 </ b> A, the core 32 </ b> A includes spherical resin particles 42 and a metal layer 44 that covers the surfaces of the resin particles 42. The material of the resin particles 42 is not particularly limited, but it is preferable to use a resin having high heat resistance and a large elastic modulus (for example, divinylbenzene crosslinked polymer, cured products of various thermosetting resins, crosslinked polyester). The metal layer 44 can contain the same first metal (Cu or Cu alloy having a melting point of 1000 ° C. or higher) as in the first embodiment. As the adhesive contained in the solder-resin mixture of the second embodiment, the adhesive 28 of the first embodiment can be used. The content of the granular material 30A is the same as that in the first embodiment.

  The diameter of the granular material 30 </ b> A is preferably 2 to 100 μm similarly to the granular material 30, and the thickness of the solder layer 34 </ b> A is preferably 0.1 to 10 μm similarly to the solder layer 34. The composition of the solder layer 34A is the same as that of the solder layer 34. The diameter of the resin particle 42 can be 1 to 90 μm. The average thickness of the metal layer 44 can be 0.1 to 5 μm. A component mounting method and a component mounting system for mounting the electronic component 12 on the substrate 14 using the solder-resin mixture including the granular material 30A as described above are the same as those in the first embodiment.

  In the component mounting structure manufactured using the granular material 30 </ b> A as described above, the joint portion 17 </ b> A is formed between the corresponding electrodes in the first portion 29 b of the resin reinforcing portion 29. The joint portion 17A includes a metal layer 44 covering the surface of the spherical resin particles 42, an intermetallic compound layer 38A covering the surface of the metal layer 44, and a solidified solder 40A on the outside thereof. The thickness of the metal layer 44 is smaller than the thickness of the original metal layer 44 of the granular material 30A. Alternatively, all of the first metals included in the metal layer 44 of the granular material 30 </ b> A may be changed to intermetallic compounds, so that the joint portion 17 </ b> A may not have the metal layer 44. In this case, the resin particles 42 and the intermetallic compound layer 38A are in direct contact. Further, since the second metal contained in the solder layer 34A of the granular material 30A is all changed to an intermetallic compound layer, the joint 17A may not have the solidified solder 40A.

  In the 2nd part 29a of the resin reinforcement part 29, the granular material 30A is heated, and the intermetallic compound layer containing granular material 31A is formed. The intermetallic compound layer-containing granular material 31A includes resin particles 42, a metal layer 44 containing a first metal, an intermetallic compound layer 38A of a first metal and a second metal, and a solder layer made of solidified solder 40A. Contains. Note that, when the first metal is sufficiently diffused into the molten solder, the metal layer 44 may disappear from the intermetallic compound layer-containing granular material 31A. Similarly, the second metal contained in the solder layer 34A of the granular material 30A is changed to an intermetallic compound layer, so that the intermetallic compound layer-containing granular material 31A may not have the solidified solder 40A. .

  As described above, by including the resin particles 42 in the core 32A, the amount of the first metal used can be suppressed, and the cost can be easily reduced. Further, by using a material having a certain degree of rigidity for the resin particles 42, it is possible to prevent the resin particles 42 sandwiched between the corresponding electrodes from being crushed even when the electrodes are joined by thermocompression bonding. it can. Thereby, it becomes easy to make the gap between corresponding electrodes into a desired gap, and it becomes easy to connect the electronic component 12 and the substrate 14 so that the transmission line length becomes as designed.

Next, Embodiment 3 of the present invention will be described.
(Embodiment 3)
In FIG. 12, the principal part of the component mounting structure manufactured by the component mounting method which concerns on this embodiment is expanded and shown. In the mounting method of the third embodiment, a component mounting structure is manufactured using a solder-resin mixture containing silica (SiO ₂ ) and an inorganic filler such as alumina. Other than that, the component mounting method and the component mounting system of the present embodiment are the same as the component mounting method and the component mounting system of the first and second embodiments. Thus, as shown in FIG. 12, the resin reinforcing portion 29, silica (SiO _2), and may be free of inorganic filler 45 such as alumina.

  As a result, the elastic modulus can be increased while reducing the thermal expansion coefficient of the resin reinforcing portion 29. Thereby, even when a heat cycle that is cooled after the component mounting structure is heated is applied to the component mounting structure, deterioration of the resin reinforcing portion 29 such as a crack in the resin reinforcing portion 29 is suppressed. It becomes possible. Moreover, the impact resistance of the resin reinforcement part 29 is improved. Furthermore, since the moisture absorption rate of the resin reinforcing part 29 can be lowered, it is possible to prevent the electrodes and wiring from being corroded. In addition, it is preferable that content of the inorganic filler 45 with respect to the whole solder-resin mixture including the inorganic filler 45 shall be 10-50 volume%.

  The diameter Dk of the inorganic filler 45 is made smaller than the diameter Dr of the granular material 30 (Dk <Dr). For example, it can be about 2 μm ≧ Dk ≧ 0.1 μm. If the mere solder particles 48 are used in place of the granular materials 30 or 30A as in the conventional example shown in FIG. 13, the solder particles 48 have no core, and therefore, when melted, they endlessly collapse. As a result, it is conceivable that the inorganic filler 45 is sandwiched between the component electrode 16 and the land electrode 18 and the wetness of the molten solder 49 to each electrode is prevented. Thereby, connection reliability falls. In the component mounting method according to the third embodiment, since the diameter Dk of the inorganic filler 45 is smaller than the diameter Dr of the granular material 30 and the granular material including the core 32 or the core 32A is used, the inorganic filler 45 and the component electrode 16 are used. It is not sandwiched between the land electrodes 18. Therefore, the inconvenience described above can be prevented.

(Embodiment 4)
FIG. 14 is a block diagram showing a mounting line that is a component mounting system according to the present embodiment. Similar to the line 10 of the first embodiment, the line 10A in the illustrated example mounts the electronic component 12 that is a module in which a semiconductor chip or the like is mounted on a flexible board on a rigid or flexible board 14 that is a circuit board of an electronic device. It is a mounting line for. The line 10A includes a substrate supply unit 1 that supplies the substrate 14 to the line, a mixture supply unit 2 that supplies the solder-resin mixture to the land electrode 18 that is an electrode of the substrate 14, and a structure recovery unit 4. This is the same as the line 10 of the first embodiment.

  The line 10A differs from the line 10 in that a thermocompression bonding unit 3A is provided instead of the thermocompression bonding / heating unit 3, and a post-heating unit 3B is disposed between the thermocompression bonding unit 3A and the structure recovery unit 4. It is a point. Hereinafter, the different points will be mainly described.

  In the thermocompression bonding unit 3A, only the thermocompression processing shown in FIGS. 7 and 8 is performed, and the melting point shift promotion processing shown in FIG. 9 is not performed. Heating for the melting point shift promotion process is performed in the post-heating unit 3B.

  15 and 16 show specific examples of the post-heating unit. In the example of FIG. 15, the post-heating unit 3 </ b> B has an oven 50. The oven 50 is included in the core 32 or 32A, and the accommodating portion 52 that accommodates the electronic component 12 and the substrate 14 (hereinafter referred to as a structure precursor or simply a precursor) bonded to each other after being subjected to thermocompression treatment. A heater 54 for heating the joint portion of the precursor 53 accommodated in the accommodating portion 52 is included so as to promote mutual diffusion between the first metal and the molten solder 36. The accommodating portion 52 is preferably capable of accommodating the plurality of precursors 53 so that the melting point shift promoting process can be simultaneously performed on the plurality of precursors 53. Thereby, when the processing time for the melting point shift promotion process is longer than that for the thermocompression bonding process, it is possible to prevent the tact time of the line from becoming longer due to that. Therefore, production efficiency can be improved. The heating temperature and heating time of the joint portion 17 in the oven 50 are the same as those in the first to third embodiments.

  As described above, by providing the post-heating unit 3B independently of the thermocompression bonding unit 3A, the post-heating unit 3B performs the melting point shift promotion process while the thermocompression bonding process is performed by the thermocompression bonding unit 3A. be able to. As a result, the tact time of the line can be shortened and the production efficiency can be increased.

  In the example of FIG. 16, the post-heating unit 3 </ b> B includes a press machine 56. The press machine 56 includes a press plate 58 and a press stand 60. At least one of the press plate 58 and the press table 60 can be provided with heaters 62 and 64. It is preferable that the shape and area of the press table 60 be a shape and area on which the plurality of precursors 53 can be placed so that the melting point shift promoting process can be simultaneously performed on the plurality of precursors 53. Similarly, the shape and area of the press plate 58 are also preferably set to a shape and area that can simultaneously press the plurality of electronic components 12 toward the substrate 14. Thereby, when the processing time for the melting point shift promotion process is longer than that for the thermocompression bonding process, it is possible to prevent the tact time of the line from becoming longer due to that.

  According to the present invention, when a plurality of first electrodes of a first object and a plurality of second electrodes of a second object are solder-bonded by thermocompression bonding and the joint is reinforced with a resin, The remelting temperature of the part can be sufficiently increased, and a short circuit between adjacent electrodes can be prevented. Therefore, the present invention is useful for application to the manufacture of portable electronic devices that are required to be downsized.

DESCRIPTION OF SYMBOLS 1 ... Substrate supply unit, 2 ... Mixture supply unit, 3A ... Thermocompression bonding unit, 3B ... Post-heating unit, 4 ... Structure recovery unit, 6 ... Electronic component supply device, 8 ... Conveyor 10, 10A ... Line, 12 ... Electronic components, 14 ... Substrate, 16 ... Component electrode, 17 ... Junction, 18 ... Land electrode, 20 ... Thermocompression bonding head, 22,27,54,62,64 ... Heater, 24,60 ... Press stand, 26 ... Resin Mixture, 28 ... Adhesive, 29 ... Resin reinforcement, 3 ... Thermocompression bonding / heating unit, 30, 30A ... Granular matter, 32, 32A ... Core, 34 ... Solder layer, 36 ... Molten solder, 38 ... Intermetallic compound, DESCRIPTION OF SYMBOLS 40 ... Solidified solder, 42 ... Resin particle, 44 ... Metal layer, 45 ... Inorganic filler, 50 ... Oven, 52 ... Storage part, 53 ... Precursor, 56 ... Press machine, 58 ... Press plate, ... Press stand,

Claims (12)

Preparing a first object having a plurality of first electrodes;
Preparing a second object as an electronic component having a plurality of second electrodes corresponding to the plurality of first electrodes;
A solder layer including a granular material and a thermosetting resin, wherein the granular material covers a core including a first metal, and a second metal having a melting point lower than that of the first metal. And supplying the first electrode with a resin-solder mixture in which the first metal is in contact with the solder layer and the first metal and the second metal can form an intermetallic compound. Process,
Mounting the second object on the first object such that the plurality of second electrodes respectively land on the corresponding first electrode via the solder-resin mixture;
Thermocompression bonding the plurality of second electrodes and the corresponding first electrode to form a joint including the first metal and the second metal, and heating the joint, A step of accelerating the formation of an intermetallic compound by mutual diffusion of the first metal and the second metal at the joint, and curing the thermosetting resin;
A component mounting method.   The component mounting method according to claim 1, wherein the core includes resin particles, and the first metal is interposed between the resin particles and the solder layer.   The component mounting method according to claim 1, wherein an average particle diameter of the granular material is 2 to 100 μm.   The component mounting method according to claim 1, wherein the solder layer has a thickness of 0.1 to 10 μm.   The component mounting method according to any one of claims 1 to 4, wherein a content of the granular material contained in the solder-resin mixture is 0.1 to 10% by volume.   The component mounting method according to claim 1, wherein the first metal includes Cu.   The component mounting method according to claim 1, wherein the second metal includes at least one selected from the group consisting of Sn, Pb, Ag, Zn, Bi, In, Cu, and Sb. .   The component mounting method according to claim 1, wherein the solder-resin mixture further includes an inorganic filler having an average particle diameter smaller than that of the granular material. A holding unit for holding a first object having a plurality of first electrodes;
Including a granular material and a thermosetting resin, wherein the granular material includes a core including a first metal, and a solder layer covering a surface of the core and including a second metal having a lower melting point than the first metal, A mixture supply unit that supplies the first electrode with a solder-resin mixture in which the first metal is in contact with the solder layer and the first metal and the second metal can form an intermetallic compound. When,
The second object as an electronic component having a plurality of second electrodes corresponding to the plurality of first electrodes is held, and the solder-resin mixture to the first electrode corresponding to each of the plurality of second electrodes. A mounting unit for mounting the second object on the first object so as to land via
While the mounting unit presses the second object toward the first object and heats the second object, the plurality of second electrodes and the corresponding first electrode By thermocompression bonding, a joint portion including the first metal and the second metal is formed, and the joint portion is further heated, thereby causing mutual diffusion of the first metal and the second metal at the joint portion. A component mounting system that promotes generation of an intermetallic compound and cures the thermosetting resin. A holding unit for holding a first object having a plurality of first electrodes;
Including a granular material and a thermosetting resin, wherein the granular material includes a core including a first metal, and a solder layer covering a surface of the core and including a second metal having a lower melting point than the first metal, A mixture supply unit that supplies the first electrode with a solder-resin mixture in which the first metal is in contact with the solder layer and the first metal and the second metal can form an intermetallic compound. When,
The second object as an electronic component having a plurality of second electrodes corresponding to the plurality of first electrodes is held, and the solder-resin mixture to the first electrode corresponding to each of the plurality of second electrodes. The second object is mounted on the first object so as to land via the first object, the second object is pressed toward the first object, and the second object is heated. By mounting the plurality of second electrodes and the corresponding first electrode by thermocompression bonding, a mounting unit that forms a joint including the first metal and the second metal,
By further heating the joint in a state where the second object mounted on the first object is stored or held, the first metal and the second metal are interdiffused at the joint. A component mounting system including: a post-heating unit that promotes generation of an intermetallic compound and cures the thermosetting resin.   The said post-heating unit includes the oven which comprised the storage part which accommodates the said 1st target object and the said 2nd target object which have the said junction part, and the heater which heats the said junction part. Component mounting system. The post-heating unit includes a press machine having a press stand in contact with the first object and a press plate in contact with the second object;
The component mounting system according to claim 10, wherein at least one of the press table and the press plate includes a heater that heats the joint.

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