WO2011138921A1 - Structure for mounting electronic circuit configuration component - Google Patents

Structure for mounting electronic circuit configuration component Download PDF

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Publication number
WO2011138921A1
WO2011138921A1 PCT/JP2011/060345 JP2011060345W WO2011138921A1 WO 2011138921 A1 WO2011138921 A1 WO 2011138921A1 JP 2011060345 W JP2011060345 W JP 2011060345W WO 2011138921 A1 WO2011138921 A1 WO 2011138921A1
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WO
WIPO (PCT)
Prior art keywords
solder
electrode land
electronic circuit
component
central region
Prior art date
Application number
PCT/JP2011/060345
Other languages
French (fr)
Japanese (ja)
Inventor
恵子 上之
薫 内山
淳 松井
Original Assignee
日立オートモティブシステムズ株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 日立オートモティブシステムズ株式会社 filed Critical 日立オートモティブシステムズ株式会社
Publication of WO2011138921A1 publication Critical patent/WO2011138921A1/en

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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
    • H05K1/11—Printed elements for providing electric connections to or between printed circuits
    • H05K1/111—Pads for surface mounting, e.g. lay-out
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/48—Manufacture or treatment of parts, e.g. containers, prior to assembly of the devices, using processes not provided for in a single one of the subgroups H01L21/06 - H01L21/326
    • H01L21/4814—Conductive parts
    • H01L21/4846—Leads on or in insulating or insulated substrates, e.g. metallisation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/10—Bump connectors; Manufacturing methods related thereto
    • H01L2224/15—Structure, shape, material or disposition of the bump connectors after the connecting process
    • H01L2224/16—Structure, shape, material or disposition of the bump connectors after the connecting process of an individual bump connector
    • H01L2224/161—Disposition
    • H01L2224/16151—Disposition the bump connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
    • H01L2224/16221—Disposition the bump connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
    • H01L2224/16225—Disposition the bump connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being non-metallic, e.g. insulating substrate with or without metallisation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/80—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected
    • H01L2224/81—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected using a bump connector
    • 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
    • H05K2201/0332—Structure of the conductor
    • H05K2201/0364—Conductor shape
    • H05K2201/0367—Metallic bump or raised conductor not used as solder bump
    • 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
    • H05K2201/09818—Shape or layout details not covered by a single group of H05K2201/09009 - H05K2201/09809
    • H05K2201/0989—Coating free areas, e.g. areas other than pads or lands free of solder resist
    • 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
    • H05K2201/09818—Shape or layout details not covered by a single group of H05K2201/09009 - H05K2201/09809
    • H05K2201/099—Coating over pads, e.g. solder resist partly over pads
    • 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
    • H05K3/30—Assembling printed circuits with electric components, e.g. with resistor
    • H05K3/32—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits
    • H05K3/34—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits by soldering
    • H05K3/341—Surface mounted components
    • H05K3/3431—Leadless components
    • H05K3/3436—Leadless components having an array of bottom contacts, e.g. pad grid array or ball grid array components
    • 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to an electronic circuit component mounting structure.
  • BGA mounting technology ball grid array mounting technology
  • solder paste is printed on an electrode land of a circuit board, and a ball grid array (BGA) is mounted thereon by solder reflow. It is made of a metal material. The components contained in this one type of metal material are dissolved in the metal in the solder at the time of solder reflow and are interdiffused to form a metal bond.
  • BGA ball grid array
  • BGA refers to a ball-like electrode (also referred to as a bump) formed of solder having a small diameter on the bottom surface of a package such as an integrated circuit or the like arranged in a grid with a dispenser.
  • Patent Document 1 discloses a joint structure in which a plurality of types of electrode lands having different metal diffusivities from a conductor metal member are each joined to the conductor metal member.
  • Patent Document 2 a metal thin film formed on a bonding pad of a semiconductor chip, an inverted trapezoidal first metal layer made of copper or the like and protruding from the metal thin film, and solder are used.
  • a semiconductor device that includes a configured bump electrode made of a second metal layer, and the second metal layer contains carbon, sulfur, and oxygen.
  • JP 2002-43365 A Japanese Patent Application Laid-Open No. 07-211722
  • Patent Document 1 uses the advantages of different electrode lands, it does not focus on fluidity during solder melting.
  • the electrode structure of the semiconductor device disclosed in Patent Document 2 relieves stress inside the bonded and fixed electrode structure, and this does not focus on fluidity at the time of melting the solder.
  • An object of the present invention is to flow solder in a molten state without using mechanical stirring means, and to reduce voids in the solder joint.
  • the electronic circuit component mounting structure includes an electrode land provided on a surface of a substrate of a circuit board, an electronic circuit component having a terminal and mounted on the circuit board, and the electrode land and the terminal electrically connected.
  • the electrode land has different components in the central region and the peripheral region thereof.
  • the present invention it is possible to realize an electronic circuit component mounting structure in which the flux and voids inside the solder joint are extremely small, and the solder joint reliability can be improved.
  • the present invention relates to an electronic circuit component mounting structure of a circuit board using solder, such as a ball grid array (hereinafter also referred to as BGA), and in particular, a vehicle-mounted control unit that requires long-term reliability of solder connection or a small size.
  • BGA ball grid array
  • the present invention relates to a mounting structure for electronic circuit components used in consumer electronic devices that are rapidly becoming increasingly popular.
  • the electronic circuit component mounting structure includes an electrode land provided on a surface of a substrate of a circuit board, an electronic circuit component having a terminal and mounted on the substrate, and a solder for electrically connecting the electrode land and the terminal.
  • the electrode land has different components in the central region of the surface and the peripheral region.
  • the substance transfer rate inside the solder of the component in the central region is smaller than the substance transfer rate inside the solder of the component in the peripheral region.
  • the material transfer rate inside the solder of the component in the central region is larger than the material transfer rate inside the solder of the component in the peripheral region.
  • the solder contains tin (Sn).
  • the diffusion coefficient when the component in the central region diffuses into tin is smaller than the diffusion coefficient when the component in the peripheral region diffuses into tin.
  • the diffusion coefficient when the component in the central region diffuses into tin is larger than the diffusion coefficient when the component in the peripheral region diffuses into tin.
  • the elution amount per unit area of the central region into the solder of the component in the central region is smaller than the elution amount per unit area of the peripheral region of the component in the peripheral region into the solder.
  • the amount of elution per unit area of the central region component to the solder of the central region is larger than the amount of elution per unit area of the peripheral region of the component of the peripheral region to the solder.
  • the area of the central region is 1/25 to 1/4 of the area of the entire electrode land.
  • the height of the central region is higher than the height of the peripheral region.
  • the electronic circuit component is a ball grid array
  • the solder is a ball grid array solder ball
  • the mounting board has the electronic circuit component mounting structure described above.
  • the semiconductor device includes the mounting board described above.
  • the electronic device includes the semiconductor device described above.
  • a central region and a portion other than the central region are provided on the surface portion of the electrode land of the circuit board using solder such as BGA.
  • solder such as BGA.
  • a material containing a component having a different diffusion rate to tin (Sn) which is a component of the solder at the same temperature. Since Sn is a component that forms an alloy with the elution component of the electrode land in solder bonding to ensure the bonding, the elution component of the electrode land is required to be easily eluted and diffused into Sn.
  • the diffusion rate is represented by the following mathematical formula (1) as the mass transfer rate N (kg / (m 2 ⁇ s)), and depends on the diffusion coefficient and the concentration gradient.
  • D AB is a diffusion coefficient (m 2 / s)
  • dC / dx (kg / m 4 ) is a concentration gradient.
  • the relationship of the diffusion coefficient in Sn at the same temperature of both components is (the diffusion coefficient of the component in the central region) ⁇ (the diffusion coefficient of the component in the peripheral region) or (the diffusion coefficient of the component in the central region)> (the component in the peripheral region) Diffusion coefficient).
  • materials including components having different eutectic temperatures of Sn in the central region and the peripheral region are disposed.
  • the electronic devices include various on-vehicle control units, consumer electronic devices, and the like.
  • the vehicle-mounted control unit includes control devices such as an engine and a brake, a car navigation system, and the like.
  • Consumer electronic devices include personal computers, mobile phones, game machines, display devices including liquid crystal displays and plasma displays, video cameras, printers, electronic notebooks, electronic dictionaries, and the like.
  • FIG. 1 shows a cross-sectional view of the entire structure after BGA mounting.
  • a BGA substrate 6 is bonded to the surface of the base material 2 of the circuit board via solder balls 5.
  • the surface opposite to the bonding surface of the BGA substrate 6 is covered with a sealing resin 10.
  • FIG. 2 is a top view showing an electrode land of a circuit board on which a BGA solder ball is mounted.
  • the electrode lands 3 and 4 are installed on the surface of the substrate 2 of the circuit board.
  • the electrode land 101 represents the entire electrode land including the electrode lands 3 and 4.
  • the surface of the base material 2 around the electrode land 4 is covered with a resist 1.
  • a gap is provided between the electrode land 4 and the resist 1, and the surface of the substrate 2 is exposed. That is, the resist 1 has an NSMD structure (Non Solder Mask Defined) that does not cover the electrode lands 3 and 4.
  • the electrode land 4 is circular, and the circular electrode land 3 is installed in the central region of the surface. In other words, the central region of the electrode land 4 is covered with the electrode land 3, and the peripheral region (peripheral portion) of the electrode land 4 is exposed.
  • the electrode land 3 and the electrode land 4 are made of different materials. As these materials, metal materials or ceramics containing components that elute into the solder during soldering are desirable.
  • FIG. 3 is a cross-sectional view of the electrode land of FIG.
  • the electrode land 3 is installed in the central region of the surface of the electrode land 4 installed on the surface of the base material 2 of the circuit board. That is, the height of the electrode land 3 is higher than the height of the electrode land 4. Further, the portion of the electrode land 4 whose surface is exposed constitutes a peripheral region (peripheral portion) of the electrode lands 3 and 4.
  • the diffusion rate (diffusion coefficient) in the contained tin (Sn) Comparing the diffusion rate (diffusion coefficient) in the contained tin (Sn), the diffusion rate (diffusion coefficient) of the component contained in the electrode land 3 in Sn is smaller than that of the component contained in the electrode land 4. It is.
  • the eutectic temperature of Sn which is a component contained in the electrode land 3 and is eluted into the solder during soldering, is a component contained in the electrode land 4 and is eluted into the solder during soldering. It differs from the eutectic temperature of the component with Sn.
  • FIG. 4 is a cross-sectional view showing the solder joint after BGA mounting.
  • FIG. 1 This figure is an enlarged view of the solder joint portion 9 of FIG. 1, and the electrode lands 3 and 4 are those shown in FIGS.
  • a terminal 21 and a resist 7 are provided on the surface of the BGA substrate 6 on the circuit board side.
  • a gap is provided between the terminal 21 and the resist 7.
  • solder ball 5 is joined to the terminal 21 and the electrode lands 3 and 4 without contacting the resists 1 and 7.
  • One solder ball 5 of the BGA substrate 6 is bonded to one electrode land 3 and 4 correspondingly.
  • the electronic circuit component mounting structure shown in this figure includes electrode lands 3 and 4 provided on the surface of the substrate 2 of the circuit board, a component 22 such as an integrated circuit (electronic circuit component) mounted on the substrate 2, It includes solder 5 that electrically connects the electrode lands 3 and 4 and the terminal 21 of the component 22, and the components of the surface of the electrode lands 3 and 4 are made different between the central region and the peripheral region. As a result, a difference occurs in the diffusion rate of the components of the electrode lands 3 and 4 when the solder 5 is melted, and a flow accompanying the diffusion occurs inside the solder 5 in a liquid state, and the stirring of the solder 5 is promoted.
  • the circuit board means a board before mounting components such as an integrated circuit (chip).
  • the mounting substrate refers to a substrate after mounting components.
  • the shape of the electrode lands 3 and 4 is not limited to the circular shape shown in FIG.
  • FIG. 5 shows an example in which only the central region of the electrode land is elliptical.
  • the electrode land 4 is circular, and the electrode land 3 (central region) is elliptical.
  • FIG. 6 shows an example in which the central region and the peripheral region of the electrode land are elliptical.
  • the electrode land 3 central region
  • the electrode land 4 peripheral region
  • the shape of the gap between the resist 1 and the electrode land 4 is also an elliptical annular shape.
  • FIG. 7 shows the electrode land having an SMD structure (Solder Mask Defined).
  • FIG. 8 shows a cross-sectional view of the electrode land of FIG.
  • FIG. 9 shows an example in which the electrode land has an SMD structure and has an elliptical shape.
  • the cross-sectional shape of the electrode land is the same as that shown in FIG.
  • the electrode land of the embodiment can adopt not only the NSMD structure but also the SMD structure.
  • 10A, 10B and 10C show the flow of the mounting process. These drawings show the process of installing the BGA on the circuit board.
  • solder paste 11 is printed on the electrode land 101 provided on the substrate 2 of the circuit board (FIG. 10A: printing process).
  • solder balls 102 previously attached to the BGA substrate 6 of the BGA 8 are placed on the surface of the solder paste 11 (FIG. 10B: installation step).
  • the circuit board on which the BGA 8 is installed is heated in a reflow furnace, the solder is melted, the BGA 8 and the circuit board are joined, and the mounting board 12 is obtained (FIG. 10C: reflow process).
  • the inside of the reflow furnace is a nitrogen atmosphere (the oxygen concentration is, for example, 1000 ppm or less).
  • the electrode land on which the solder ball is installed is a combination of two kinds of materials, and the material is different in the central region and the peripheral region of the electrode land. Then, [Diffusion rate (diffusion coefficient) of the component of the electrode land central region in Sn] ⁇ [Diffusion rate (diffusion coefficient) of the component of the electrode land peripheral region in Sn] or [Component of the component of the electrode land central region] Since the diffusion rate (diffusion coefficient) in Sn >> [diffusion rate (diffusion coefficient) of the component of the electrode land peripheral region in Sn]], when the solder is melted in the reflow process, the electrode land central region and the electrode land periphery A flow is generated inside the solder alloy based on the difference in diffusion rate of the component of the electrode land between the regions.
  • 11 to 13 show modified examples of the electrode land.
  • FIG. 11 is a top view showing a case where the outer shape of the electrode land is a horizontally long rectangle and the center area of the electrode land is substantially square.
  • the electrode land 4 constituting the peripheral region of the electrode land is a horizontally long rectangle, and the electrode land 3 constituting the central region of the electrode land is substantially square.
  • the solder bonded to the electrode lands 3 and 4 may be ball-shaped (solder ball) or linear (thread-shaped).
  • FIG. 12 is a top view showing a case where the outer shape of the electrode land is a horizontally long rectangle and the center area of the electrode land is a vertically long rectangle.
  • the electrode land 4 constituting the peripheral region of the electrode land is a horizontally long rectangle.
  • the electrode land 3 constituting the central region of the electrode land is a vertically long rectangle, and its end portion reaches the upper side and the lower side of the electrode land 4.
  • the solder bonded to the electrode lands 3 and 4 may be ball-shaped (solder ball) or linear (thread-shaped).
  • FIG. 13 is a top view showing a case where the electrode land is a vertically long rectangle and the center area of the electrode land is a vertically long rectangle.
  • the electrode land 4 constituting the peripheral region of the electrode land is a vertically long rectangle.
  • the electrode land 3 constituting the central region of the electrode land is also a vertically long rectangle, and its end portion reaches the upper side and the lower side of the electrode land 4.
  • the solder to be joined to the electrode lands 3 and 4 may be ball-shaped (a plurality of solder balls arranged linearly on the surface of the electrode land 3), or may be linear (thread-like or plate-like). Also good.
  • the same stirring action as that of the circular electrode land can be generated by making the components different between the central region and the peripheral region of the electrode lands 3 and 4.
  • an agitating action is generated by causing an upward flow or a downward flow in the side surface portion of the solder.
  • FIG. 14 is a top view showing a modification of the combination of the electrode land and the solder ball, and shows a case where one electrode land is joined by four solder balls.
  • the electrode lands 3 and 4 are both horizontally long rectangles, and the solder balls 5 are installed at the four rectangular corners of the electrode lands 3.
  • the solder balls 5 are installed at the four rectangular corners of the electrode lands 3.
  • 15A to 15D show a case where an integrated circuit having a terminal on a side surface portion is mounted on a circuit board.
  • FIG. 15A is a top view showing a circuit board having six electrode lands.
  • the circuit board shown in this figure is for joining six terminals provided on one integrated circuit to six electrode lands 31.
  • the electrode land 31 is formed by a vertically long rectangular electrode land 41 constituting a peripheral region and a horizontally long rectangular electrode land 42 constituting a central region. Thereby, the same stirring action as the case of FIG. 12 can be produced.
  • FIG. 15B is a cross-sectional view showing a process of installing an integrated circuit on a circuit board (integrated circuit installation process).
  • terminals 34 are provided on both sides of the integrated circuit 33.
  • a solder paste 32 is applied (printed) to the electrode lands 31 of the substrate 2 of the circuit board.
  • the integrated circuit 33 is installed on the circuit board so that the terminal 34 and the electrode land 31 (solder paste 32) are in contact with each other.
  • FIG. 15C is a top view showing the integrated circuit mounting process (integrated circuit installation process) of FIG. 15B.
  • the terminal 34 is installed in contact with the electrode land 31.
  • FIG. 15D is a cross-sectional view illustrating a process of bonding an integrated circuit to a circuit board (an integrated circuit bonding process).
  • solder 35 (the solder paste 32 in FIG. 15A) is melted by reflow, and the terminals 34 and the electrode lands 31 are soldered (joined).
  • the solder 35 is attached not only to the side surface portion of the terminal 34 but also to the upper surface portion. This is due to the wettability of the solder 35 to the surface of the terminal 34.
  • FIG. 16 is a cross-sectional view showing an example of a solder ball flow state during heating.
  • the basic configuration is the same as the electronic circuit component mounting structure of FIG.
  • the components of the electrode lands 3 and 4 are eluted in the solder ball 5, and flow occurs inside the solder ball 5 due to the difference in diffusion coefficient and elution amount of each component.
  • the diffusion component 111 of the electrode land 4 constituting the peripheral region has a faster flow velocity due to the diffusion than the diffusion component 112 of the electrode land 3 constituting the central region. For this reason, in the vicinity of the outer surface of the liquid solder ball 5, the flow velocity going upward in the figure tends to be high, and in the central axis portion of the liquid solder ball 5, the flow velocity going downward in the figure tends to be high.
  • FIG. 17 is a cross-sectional view showing another example of a solder ball flow state during heating.
  • the diffusion component 112 of the electrode land 3 constituting the central region has a higher flow velocity due to the diffusion than the diffusion component 111 of the electrode land 4 constituting the peripheral region. For this reason, in the vicinity of the outer surface of the liquid solder ball 5, the flow velocity going downward in the figure tends to be fast, and in the central axis portion of the liquid solder ball 5, the flow velocity going upward in the figure tends to be high.
  • the eutectic temperature of Sn is different between Ni and Au, the eutectic temperature of Ni and Sn is 221 ° C., and the eutectic temperature of Au and Sn is 280 ° C.
  • the material of the electrode land 3 central region
  • the material of the electrode land 4 peripheral region
  • the same temperature [Diffusion rate of Ni in Sn (diffusion coefficient)] ⁇ [Diffusion rate of Cu in Sn (diffusion coefficient)].
  • the eutectic temperature of Sn is different between Ni and Cu, the eutectic temperature of Ni and Sn is 221 ° C., and the eutectic temperature of Cu and Su is 227 ° C.
  • the eutectic temperature of Sn is different between Cu and Au, the eutectic temperature of Cu and Sn is 227 ° C., and the eutectic temperature of Au and Su is 280 ° C.
  • solder joint reliability it is possible to realize an electronic circuit component mounting structure in which solder flux and voids in a solder joint such as a BGA are extremely small, and the solder joint reliability can be improved.
  • a control unit mounted on an automobile is required to have a long life of 10 years or more, and the bonding reliability of the solder joint is very important.
  • the present invention since there are very few voids and flux inside the solder, which are likely to promote the progress of solder breakage, it is possible to extend the life of the solder joint.
  • the present invention since there are very few voids inside the solder, it is possible to realize a highly reliable solder joint corresponding to the reduction in the diameter and pitch of the electrode land.

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Electric Connection Of Electric Components To Printed Circuits (AREA)
  • Wire Bonding (AREA)

Abstract

Disclosed is a structure for mounting an electronic circuit configuration component, wherein voids inside of a solder bonding section are reduced. The structure includes: an electrode land (3, 4), which is provided on the surface of the base material (2) of a circuit board; a component (22) to be mounted on the circuit board; and a solder (5), which electrically connects together the electrode land (3, 4) and the terminals (21) of the component (22). The components of the center region and those of the peripheral region on the surface of the electrode land are made different from each other. Consequently, when the solder (5) is melted, a substance transfer speed difference is generated in elution of the components of the electrode land (3, 4), and stirring is promoted due to flowage generated by diffusion of the components of the electrode land (3, 4) inside of the solder (5) in the liquid state.

Description

電子回路構成部品実装構造Electronic circuit component mounting structure
　本発明は、電子回路構成部品実装構造に関する。 The present invention relates to an electronic circuit component mounting structure.
　回路基板に集積回路等を実装する技術の一つとしてボールグリッドアレイ実装技術（ＢＧＡ実装技術）がある。 There is a ball grid array mounting technology (BGA mounting technology) as one of the technologies for mounting an integrated circuit or the like on a circuit board.
　従来のＢＧＡ実装技術は、回路基板の電極ランドにはんだペーストを印刷し、その上部にボールグリッドアレイ（Ｂａｌｌ　Ｇｒｉｄ　Ａｒｒａｙ：ＢＧＡ）をはんだリフローにより実装するものであり、電極ランドの表面は、１種類の金属材料で形成されている。
この１種類の金属材料に含まれる成分がはんだリフロー時にはんだ中の金属に溶解して相互拡散し、金属結合を形成する。 In the conventional BGA mounting technology, a solder paste is printed on an electrode land of a circuit board, and a ball grid array (BGA) is mounted thereon by solder reflow. It is made of a metal material.
The components contained in this one type of metal material are dissolved in the metal in the solder at the time of solder reflow and are interdiffused to form a metal bond.
　ここで、ＢＧＡとは、集積回路等のパッケージの底面に径の小さいはんだで形成されたボール状電極（バンプともいう。）をディスペンサで格子状に並べたものをいう。 Here, BGA refers to a ball-like electrode (also referred to as a bump) formed of solder having a small diameter on the bottom surface of a package such as an integrated circuit or the like arranged in a grid with a dispenser.
　特許文献１には、導体金属部材との金属の拡散性が異なる複数種類の電極ランドが各々、導体金属部材と接合されている接合構造が開示されている。 Patent Document 1 discloses a joint structure in which a plurality of types of electrode lands having different metal diffusivities from a conductor metal member are each joined to the conductor metal member.
　特許文献２には、半導体チップのボンディングパッド上に形成された金属薄膜と、この金属薄膜上に突出して形成された、銅などで構成された逆台形状の第１の金属層、及びはんだで構成された第２の金属層からなるバンプ電極とを具備し、第２の金属層が炭素、硫黄及び酸素を含有する半導体装置が開示されている。 In Patent Document 2, a metal thin film formed on a bonding pad of a semiconductor chip, an inverted trapezoidal first metal layer made of copper or the like and protruding from the metal thin film, and solder are used. There is disclosed a semiconductor device that includes a configured bump electrode made of a second metal layer, and the second metal layer contains carbon, sulfur, and oxygen.
特開２００２－４３３６５号公報JP 2002-43365 A 特開平０７－２１１７２２号公報Japanese Patent Application Laid-Open No. 07-211722
　特許文献１の接合構造は、異なる電極ランドの長所を利用するものであるが、はんだ溶融時における流動性に着眼したものではない。 Although the joint structure of Patent Document 1 uses the advantages of different electrode lands, it does not focus on fluidity during solder melting.
　また、特許文献２の半導体装置の電極構造は、接合されて固定された電極構造の内部における応力を緩和するものであり、これもはんだ溶融時における流動性に着眼したものではない。 Further, the electrode structure of the semiconductor device disclosed in Patent Document 2 relieves stress inside the bonded and fixed electrode structure, and this does not focus on fluidity at the time of melting the solder.
　従来技術においては、リフロー工程におけるはんだ溶融時、電極ランドの表面又ははんだ合金の内部に残留したフラックス、及びフラックスから発生するガスがはんだ外部へ抜け難く、リフロー後のはんだの内部にボイドが残留しやすい。はんだ内部のボイドは、はんだの機械的及び電気的な接合信頼性に影響を与えるため、フラックス及びボイドを極力低減することが課題となっている。 In the prior art, when solder is melted in the reflow process, the flux remaining on the surface of the electrode land or inside the solder alloy and the gas generated from the flux are difficult to escape to the outside of the solder, and voids remain inside the solder after reflow. Cheap. Since voids in the solder affect the mechanical and electrical bonding reliability of the solder, it is an issue to reduce the flux and void as much as possible.
　はんだの内部のフラックス及びボイドを除去するためには、はんだを溶融させた際に液状のはんだを十分に流動させる必要がある。しかし、ＢＧＡのように多数のはんだボールのリフローを行う場合、はんだの内部に機械的な攪拌手段を設けることは困難である。 In order to remove the flux and voids inside the solder, it is necessary to sufficiently flow the liquid solder when the solder is melted. However, when reflowing a large number of solder balls like BGA, it is difficult to provide mechanical stirring means inside the solder.
　本発明は、機械的な攪拌手段を用いることなく、溶融状態にあるはんだを流動させ、はんだ接合部の内部におけるボイドを低減することを目的とする。 An object of the present invention is to flow solder in a molten state without using mechanical stirring means, and to reduce voids in the solder joint.
　本発明の電子回路構成部品実装構造は、回路基板の基材の表面に設けた電極ランドと、端子を有し前記回路基板に実装する電子回路構成部品と、前記電極ランドと前記端子とを電気的に接続するはんだとを含むものであって、前記電極ランドは、その表面の中央領域とその周辺領域とで成分が異なることを特徴とする。これにより、前記はんだを溶融した際、前記中央領域及び前記周辺領域の成分の溶出における物質伝達速度（拡散速度）に差が生じ、液状となった前記はんだの内部における前記中央領域及び前記周辺領域の成分の拡散に伴う流動により撹拌が促進される。 The electronic circuit component mounting structure according to the present invention includes an electrode land provided on a surface of a substrate of a circuit board, an electronic circuit component having a terminal and mounted on the circuit board, and the electrode land and the terminal electrically connected. The electrode land has different components in the central region and the peripheral region thereof. Thereby, when the solder is melted, a difference occurs in the mass transfer rate (diffusion rate) in the elution of the components in the central region and the peripheral region, and the central region and the peripheral region in the solder that has become liquid Agitation is promoted by the flow accompanying the diffusion of the components.
　本発明によれば、はんだ接合部の内部のフラックス及びボイドが極めて少ない電子回路構成部品実装構造を実現することができ、はんだの接合信頼性を向上させることができる。 According to the present invention, it is possible to realize an electronic circuit component mounting structure in which the flux and voids inside the solder joint are extremely small, and the solder joint reliability can be improved.
実施例に係る実装基板の全体構成を示す断面図である。It is sectional drawing which shows the whole structure of the mounting substrate which concerns on an Example. 実施例に係る電極ランド（ＮＳＭＤ構造、円形）を示す上面図である。It is a top view which shows the electrode land (NSMD structure, circular) which concerns on an Example. 図２の電極ランドを示す断面図である。It is sectional drawing which shows the electrode land of FIG. 実施例に係る電子回路構成部品実装構造を示す断面図である。It is sectional drawing which shows the electronic circuit component mounting structure based on an Example. 実施例に係る電極ランド（ＮＳＭＤ構造、中央領域が楕円形）を示す上面図である。It is a top view which shows the electrode land (NSMD structure, a center area | region is an ellipse) which concerns on an Example. 実施例に係る電極ランド（ＮＳＭＤ構造、電極ランド全体が楕円形）を示す上面図である。It is a top view which shows the electrode land (NSMD structure and the whole electrode land is elliptical) which concerns on an Example. 実施例に係る電極ランド（ＳＭＤ構造、円形）を示す上面図である。It is a top view which shows the electrode land (SMD structure, circular) which concerns on an Example. 実施例に係る電極ランド（ＳＭＤ構造）を示す断面図である。It is sectional drawing which shows the electrode land (SMD structure) which concerns on an Example. 実施例に係る電極ランド（ＳＭＤ構造、電極ランド全体が楕円形）を示す上面図である。It is a top view which shows the electrode land (SMD structure and the whole electrode land is elliptical) which concerns on an Example. 実施例に係るＢＧＡ実装工程（はんだペースト印刷工程）を示す断面図である。It is sectional drawing which shows the BGA mounting process (solder paste printing process) which concerns on an Example. 実施例に係るＢＧＡ実装工程（ＢＧＡ設置工程）を示す断面図である。It is sectional drawing which shows the BGA mounting process (BGA installation process) which concerns on an Example. 実施例に係るＢＧＡ実装工程（ＢＧＡ接合工程）を示す断面図である。It is sectional drawing which shows the BGA mounting process (BGA joining process) which concerns on an Example. 電極ランドの変形例（電極ランドが横長の長方形、中央領域が略正方形）を示す上面図である。It is a top view which shows the modification of an electrode land (an electrode land is a horizontally long rectangle, a center area | region is substantially square). 電極ランドの変形例（電極ランドが横長の長方形、中央領域が縦長の長方形）を示す上面図である。It is a top view which shows the modification of an electrode land (an electrode land is a horizontally long rectangle, a center area is a vertically long rectangle). 電極ランドの変形例（電極ランドが縦長の長方形、中央領域が縦長の長方形）を示す上面図である。It is a top view which shows the modification of an electrode land (an electrode land is a vertically long rectangle, a center area | region is a vertically long rectangle). 電極ランドとはんだボールとの組み合わせの変形例（１か所の電極ランドを複数個のはんだボールで接合する場合）を示す上面図である。It is a top view which shows the modification of the combination of an electrode land and a solder ball (when the electrode land of one place is joined with several solder balls). 回路基板の変形例（１個の集積回路に対して６か所の電極ランドを有する回路基板）を示す上面図である。It is a top view which shows the modification (circuit board which has six electrode lands with respect to one integrated circuit) of a circuit board. 実施例に係る集積回路実装工程（集積回路設置工程）を示す断面図である。It is sectional drawing which shows the integrated circuit mounting process (integrated circuit installation process) which concerns on an Example. 図１５Ｂの集積回路実装工程（集積回路設置工程）を示す上面図である。It is a top view which shows the integrated circuit mounting process (integrated circuit installation process) of FIG. 15B. 実施例に係る集積回路実装工程（集積回路接合工程）を示す断面図である。It is sectional drawing which shows the integrated circuit mounting process (integrated circuit joining process) which concerns on an Example. 加熱時のはんだボールの内部における流動状態（周辺領域からの拡散の影響が大きい場合）を示す断面図である。It is sectional drawing which shows the flow state (when the influence of the diffusion from a peripheral region is large) inside the solder ball at the time of heating. 加熱時のはんだボールの内部における流動状態（中央領域からの拡散の影響が大きい場合）を示す断面図である。It is sectional drawing which shows the flow state (when the influence of the spreading | diffusion from a center area | region is large) inside the solder ball at the time of a heating.
　本発明は、ボールグリッドアレイ（以下、ＢＧＡとも呼ぶ。）等、はんだを用いる回路基板の電子回路構成部品実装構造に関し、特に、はんだ接続の長期信頼性が求められる車載用コントロールユニット、又は、小型化が急速に進む民生電子機器に用いる電子回路構成部品実装構造に関する。 The present invention relates to an electronic circuit component mounting structure of a circuit board using solder, such as a ball grid array (hereinafter also referred to as BGA), and in particular, a vehicle-mounted control unit that requires long-term reliability of solder connection or a small size. The present invention relates to a mounting structure for electronic circuit components used in consumer electronic devices that are rapidly becoming increasingly popular.
　以下、本発明の一実施形態に係る電子回路構成部品実装構造並びにこの電子回路構成部品実装構造を有する実装基板、半導体装置及び電子機器について説明する。 Hereinafter, an electronic circuit component mounting structure, a mounting substrate, a semiconductor device, and an electronic device having the electronic circuit component mounting structure according to an embodiment of the present invention will be described.
　前記電子回路構成部品実装構造は、回路基板の基材の表面に設けた電極ランドと、端子を有し基材に実装する電子回路構成部品と、電極ランドと端子とを電気的に接続するはんだとを含むものであって、電極ランドは、その表面の中央領域とその周辺領域とで成分が異なっている。 The electronic circuit component mounting structure includes an electrode land provided on a surface of a substrate of a circuit board, an electronic circuit component having a terminal and mounted on the substrate, and a solder for electrically connecting the electrode land and the terminal. The electrode land has different components in the central region of the surface and the peripheral region.
　前記電子回路構成部品実装構造において、中央領域の成分のはんだの内部における物質伝達速度は、周辺領域の成分のはんだの内部における物質伝達速度に比べて小さい。 In the electronic circuit component mounting structure, the substance transfer rate inside the solder of the component in the central region is smaller than the substance transfer rate inside the solder of the component in the peripheral region.
　前記電子回路構成部品実装構造において、中央領域の成分のはんだの内部における物質伝達速度は、周辺領域の成分のはんだの内部における物質伝達速度に比べて大きい。 In the electronic circuit component mounting structure, the material transfer rate inside the solder of the component in the central region is larger than the material transfer rate inside the solder of the component in the peripheral region.
　前記電子回路構成部品実装構造において、はんだは、スズ（Ｓｎ）を含む。 In the electronic circuit component mounting structure, the solder contains tin (Sn).
　前記電子回路構成部品実装構造において、温度が等しい場合に、中央領域の成分がスズ中に拡散する際の拡散係数は、周辺領域の成分がスズ中に拡散する際の拡散係数に比べて小さい。 In the electronic circuit component mounting structure, when the temperatures are equal, the diffusion coefficient when the component in the central region diffuses into tin is smaller than the diffusion coefficient when the component in the peripheral region diffuses into tin.
　前記電子回路構成部品実装構造において、温度が等しい場合に、中央領域の成分がスズ中に拡散する際の拡散係数は、周辺領域の成分がスズ中に拡散する際の拡散係数に比べて大きい。 In the electronic circuit component mounting structure, when the temperatures are equal, the diffusion coefficient when the component in the central region diffuses into tin is larger than the diffusion coefficient when the component in the peripheral region diffuses into tin.
　前記電子回路構成部品実装構造において、中央領域の成分のはんだへの中央領域の単位面積当たりの溶出量は、周辺領域の成分のはんだへの周辺領域の単位面積当たりの溶出量に比べて小さい。 In the electronic circuit component mounting structure, the elution amount per unit area of the central region into the solder of the component in the central region is smaller than the elution amount per unit area of the peripheral region of the component in the peripheral region into the solder.
　前記電子回路構成部品実装構造において、中央領域の成分のはんだへの中央領域の単位面積当たりの溶出量は、周辺領域の成分のはんだへの周辺領域の単位面積当たりの溶出量に比べて大きい。 In the electronic circuit component mounting structure, the amount of elution per unit area of the central region component to the solder of the central region is larger than the amount of elution per unit area of the peripheral region of the component of the peripheral region to the solder.
　前記電子回路構成部品実装構造において、中央領域の面積は、電極ランド全体の面積の２５分の１～４分の１である。 In the electronic circuit component mounting structure, the area of the central region is 1/25 to 1/4 of the area of the entire electrode land.
　前記電子回路構成部品実装構造において、中央領域の高さは、周辺領域の高さよりも高い。 In the electronic circuit component mounting structure, the height of the central region is higher than the height of the peripheral region.
　前記電子回路構成部品実装構造において、電子回路構成部品は、ボールグリッドアレイであり、はんだは、ボールグリッドアレイのはんだボールである。 In the electronic circuit component mounting structure, the electronic circuit component is a ball grid array, and the solder is a ball grid array solder ball.
　前記実装基板は、上記の電子回路構成部品実装構造を有する。 The mounting board has the electronic circuit component mounting structure described above.
　前記半導体装置は、上記の実装基板を含む。 The semiconductor device includes the mounting board described above.
　前記電子機器は、上記の半導体装置を含む。 The electronic device includes the semiconductor device described above.
　前記電子回路構成部品実装構造においては、ＢＧＡ等、はんだを用いる回路基板の電極ランドの表面部に、その中央領域と中央領域以外の部分（電極ランドの表面部の中央領域に対して周辺領域と呼ぶ。）とではんだの成分であるスズ（Ｓｎ）への拡散速度が同一温度において異なる成分を含む材料を配置する。Ｓｎは、はんだ接合において電極ランドの溶出成分と合金を形成して接合を確実にする成分であるため、電極ランドの溶出成分は、Ｓｎに溶出しやすく、拡散しやすいことがその特性として要求される。 In the electronic circuit component mounting structure, a central region and a portion other than the central region (a peripheral region with respect to the central region of the surface portion of the electrode land) are provided on the surface portion of the electrode land of the circuit board using solder such as BGA. And a material containing a component having a different diffusion rate to tin (Sn) which is a component of the solder at the same temperature. Since Sn is a component that forms an alloy with the elution component of the electrode land in solder bonding to ensure the bonding, the elution component of the electrode land is required to be easily eluted and diffused into Sn. The
　ここで、拡散速度は、物質伝達速度Ｎ（ｋｇ／（ｍ２・ｓ））として下記数式（１）で表されるものであり、拡散係数及び濃度勾配に依存する。 Here, the diffusion rate is represented by the following mathematical formula (1) as the mass transfer rate N (kg / (m 2 · s)), and depends on the diffusion coefficient and the concentration gradient.
Figure JPOXMLDOC01-appb-M000001
Figure JPOXMLDOC01-appb-M000001
　ここで、ＤＡＢは拡散係数（ｍ２／ｓ）、ｄＣ／ｄｘ（ｋｇ／ｍ４）は濃度勾配である。 Here, D AB is a diffusion coefficient (m 2 / s), and dC / dx (kg / m 4 ) is a concentration gradient.
　したがって、電極ランドから溶出してＳｎと合金を形成する成分の拡散速度（物質伝達速度Ｎ）が速いほど、すなわち、拡散係数が高く、濃度勾配が大きいほど、拡散に伴うはんだの流動による攪拌が促進される。また、濃度勾配に影響を与える因子として、電極ランドから溶出してＳｎと合金を形成する成分の溶解度がある。 Therefore, the faster the diffusion rate (material transfer rate N) of the component that elutes from the electrode land and forms an alloy with Sn, that is, the higher the diffusion coefficient and the larger the concentration gradient, the more the stirring by the flow of solder accompanying the diffusion occurs. Promoted. Further, as a factor affecting the concentration gradient, there is a solubility of a component that is eluted from the electrode land and forms an alloy with Sn.
　両成分の同一温度におけるＳｎ中における拡散係数の関係は、（中央領域の成分の拡散係数）＜（周辺領域の成分の拡散係数）又は（中央領域の成分の拡散係数）＞（周辺領域の成分の拡散係数）である。また、中央領域と周辺領域とでＳｎとの共晶温度が異なる成分を含む材料を配置する。 The relationship of the diffusion coefficient in Sn at the same temperature of both components is (the diffusion coefficient of the component in the central region) <(the diffusion coefficient of the component in the peripheral region) or (the diffusion coefficient of the component in the central region)> (the component in the peripheral region) Diffusion coefficient). In addition, materials including components having different eutectic temperatures of Sn in the central region and the peripheral region are disposed.
　はんだを溶融した際、中央領域及び周辺領域の成分の溶出における物質伝達速度（拡散速度）に差が生じ、液状となったはんだの内部における中央領域及び周辺領域の成分の拡散に伴う流動により撹拌が促進される。 When the solder is melted, there is a difference in the mass transfer rate (diffusion rate) in the elution of the components in the central region and the peripheral region. Is promoted.
　これにより、リフロー時においてはんだ合金の内部にはんだの流れを発生させ、はんだ内部に残留するフラックス及びボイドがはんだ合金の外部へ抜け易くなり、リフロー後にはんだ内部に残留するフラックス及びボイドが極めて少ない電子回路構成部品実装構造を実現する。 As a result, a solder flow is generated inside the solder alloy at the time of reflow, and the flux and voids remaining inside the solder are easily released to the outside of the solder alloy. A circuit component mounting structure is realized.
　ここで、電子機器には、各種の車載用コントロールユニット、民生電子機器等が含まれる。車載用コントロールユニットには、エンジン、ブレーキ等の制御機器、カーナビゲーションシステム等も含まれる。民生電子機器には、パーソナルコンピュータ、携帯電話、ゲーム機、液晶ディスプレイ及びプラズマディスプレイを含む表示機器、ビデオカメラ、プリンタ、電子手帳、電子辞書等も含まれる。 Here, the electronic devices include various on-vehicle control units, consumer electronic devices, and the like. The vehicle-mounted control unit includes control devices such as an engine and a brake, a car navigation system, and the like. Consumer electronic devices include personal computers, mobile phones, game machines, display devices including liquid crystal displays and plasma displays, video cameras, printers, electronic notebooks, electronic dictionaries, and the like.
　以下、図を用いて説明する。 Hereinafter, this will be described with reference to the drawings.
　図１は、ＢＧＡ実装後の全体構造断面図を示したものである。 FIG. 1 shows a cross-sectional view of the entire structure after BGA mounting.
　本図において、回路基板の基材２の表面には、ＢＧＡ基板６がはんだボール５を介して接合されている。ＢＧＡ基板６の接合面と反対側の表面は、封止樹脂１０で被覆されている。 In this figure, a BGA substrate 6 is bonded to the surface of the base material 2 of the circuit board via solder balls 5. The surface opposite to the bonding surface of the BGA substrate 6 is covered with a sealing resin 10.
　破線で囲んで示した８はＢＧＡであり、９ははんだ接合部である。 8 shown surrounded by a broken line is BGA, and 9 is a solder joint.
　図２は、ＢＧＡはんだボールを実装する回路基板の電極ランドを示す上面図である。 FIG. 2 is a top view showing an electrode land of a circuit board on which a BGA solder ball is mounted.
　電極ランド３、４は、回路基板の基材２の表面に設置してある。電極ランド１０１は、電極ランド３、４を合わせた電極ランド全体を表す。 The electrode lands 3 and 4 are installed on the surface of the substrate 2 of the circuit board. The electrode land 101 represents the entire electrode land including the electrode lands 3 and 4.
　電極ランド４の周辺の基材２の表面は、レジスト１によって被覆してある。ただし、本図においては、電極ランド４とレジスト１との間に隙間が設けてあり、基材２の表面を露出させている。すなわち、レジスト１が電極ランド３、４にかからないＮＳＭＤ構造（Ｎｏｎ　Ｓｏｌｄｅｒ　Ｍａｓｋ　Ｄｅｆｉｎｅｄ）を有している。 The surface of the base material 2 around the electrode land 4 is covered with a resist 1. However, in this figure, a gap is provided between the electrode land 4 and the resist 1, and the surface of the substrate 2 is exposed. That is, the resist 1 has an NSMD structure (Non Solder Mask Defined) that does not cover the electrode lands 3 and 4.
　また、電極ランド４は円形であり、その表面の中央領域に円形の電極ランド３が設置してある。すなわち、電極ランド４の中央領域は電極ランド３によって被覆され、電極ランド４の周辺領域（周辺部分）が露出した構成としてある。 Also, the electrode land 4 is circular, and the circular electrode land 3 is installed in the central region of the surface. In other words, the central region of the electrode land 4 is covered with the electrode land 3, and the peripheral region (peripheral portion) of the electrode land 4 is exposed.
　さらに、電極ランド３と電極ランド４とは互いに異なる材料を用いている。これらの材料としては、金属材料、又ははんだ付けの際にはんだに溶出する成分を含むセラミックス等が望ましい。 Furthermore, the electrode land 3 and the electrode land 4 are made of different materials. As these materials, metal materials or ceramics containing components that elute into the solder during soldering are desirable.
　図３は、図２の電極ランドの断面図である。 FIG. 3 is a cross-sectional view of the electrode land of FIG.
　本図においては、回路基板の基材２の表面に設置された電極ランド４の表面の中央領域に電極ランド３が設置してある。すなわち、電極ランド３の高さは、電極ランド４の高さよりも高くなっている。また、電極ランド４において表面が露出した部分は、電極ランド３、４の周辺領域（周縁部）を構成している。 In this figure, the electrode land 3 is installed in the central region of the surface of the electrode land 4 installed on the surface of the base material 2 of the circuit board. That is, the height of the electrode land 3 is higher than the height of the electrode land 4. Further, the portion of the electrode land 4 whose surface is exposed constitutes a peripheral region (peripheral portion) of the electrode lands 3 and 4.
　ここで、電極ランド３に含まれる成分であってはんだ付けの際にはんだに溶出する成分と、電極ランド４に含まれる成分であってはんだ付けの際にはんだに溶出する成分とに関して、はんだに含まれるスズ（Ｓｎ）中における拡散速度（拡散係数）を比較すると、電極ランド３に含まれる成分のＳｎ中における拡散速度（拡散係数）は、電極ランド４に含まれる成分のそれよりも小さくしてある。 Here, regarding the component contained in the electrode land 3 and eluted into the solder during soldering, and the component contained in the electrode land 4 and eluted into the solder during soldering, Comparing the diffusion rate (diffusion coefficient) in the contained tin (Sn), the diffusion rate (diffusion coefficient) of the component contained in the electrode land 3 in Sn is smaller than that of the component contained in the electrode land 4. It is.
　また、電極ランド３に含まれる成分であってはんだ付けの際にはんだに溶出する成分のＳｎとの共晶温度は、電極ランド４に含まれる成分であってはんだ付けの際にはんだに溶出する成分のＳｎとの共晶温度とは異なる。 Further, the eutectic temperature of Sn, which is a component contained in the electrode land 3 and is eluted into the solder during soldering, is a component contained in the electrode land 4 and is eluted into the solder during soldering. It differs from the eutectic temperature of the component with Sn.
　図４は、ＢＧＡ実装後のはんだ接合部を示す断面図である。 FIG. 4 is a cross-sectional view showing the solder joint after BGA mounting.
　本図は、図１のはんだ接合部９を拡大して示したものであり、電極ランド３、４は、図２及び３に示したものである。 This figure is an enlarged view of the solder joint portion 9 of FIG. 1, and the electrode lands 3 and 4 are those shown in FIGS.
　ＢＧＡ基板６の回路基板側の表面には、端子２１及びレジスト７が設けてある。端子２１とレジスト７との間には隙間が設けてある。 A terminal 21 and a resist 7 are provided on the surface of the BGA substrate 6 on the circuit board side. A gap is provided between the terminal 21 and the resist 7.
　本図において、はんだボール５は、レジスト１、７に接触することなく、端子２１及び電極ランド３、４に接合されている。１か所の電極ランド３及び４に対してＢＧＡ基板６の１個のはんだボール５が対応して接合されている。 In this figure, the solder ball 5 is joined to the terminal 21 and the electrode lands 3 and 4 without contacting the resists 1 and 7. One solder ball 5 of the BGA substrate 6 is bonded to one electrode land 3 and 4 correspondingly.
　本図に示す電子回路構成部品実装構造は、回路基板の基材２の表面に設けた電極ランド３、４と、基材２に実装する集積回路等の部品２２（電子回路構成部品）と、電極ランド３、４と部品２２の端子２１とを電気的に接続するはんだ５とを含み、電極ランド３、４の表面において中央領域と周辺領域とで成分を異ならせる。これにより、はんだ５を溶融した際における電極ランド３、４の成分の拡散速度に差が生じ、液状となったはんだ５の内部において拡散に伴う流動が生じ、はんだ５の撹拌が促進される。 The electronic circuit component mounting structure shown in this figure includes electrode lands 3 and 4 provided on the surface of the substrate 2 of the circuit board, a component 22 such as an integrated circuit (electronic circuit component) mounted on the substrate 2, It includes solder 5 that electrically connects the electrode lands 3 and 4 and the terminal 21 of the component 22, and the components of the surface of the electrode lands 3 and 4 are made different between the central region and the peripheral region. As a result, a difference occurs in the diffusion rate of the components of the electrode lands 3 and 4 when the solder 5 is melted, and a flow accompanying the diffusion occurs inside the solder 5 in a liquid state, and the stirring of the solder 5 is promoted.
　ここで、回路基板とは、集積回路（チップ）等の部品を実装する前の基板をいう。また、実装基板とは、部品を実装した後の基板をいう。 Here, the circuit board means a board before mounting components such as an integrated circuit (chip). Further, the mounting substrate refers to a substrate after mounting components.
　電極ランド３、４の形状は、図２に示す円形だけではなく、例えば、楕円の形状も可能である。 The shape of the electrode lands 3 and 4 is not limited to the circular shape shown in FIG.
　図５は、電極ランドの中央領域のみを楕円形状とした例を示したものである。 FIG. 5 shows an example in which only the central region of the electrode land is elliptical.
　本図においては、電極ランド４を円形とし、電極ランド３（中央領域）を楕円形状としてある。 In this figure, the electrode land 4 is circular, and the electrode land 3 (central region) is elliptical.
　図６は、電極ランドの中央領域及び周辺領域を楕円形状とした例を示したものである。 FIG. 6 shows an example in which the central region and the peripheral region of the electrode land are elliptical.
　本図においては、電極ランド３（中央領域）だけでなく、電極ランド４（周辺領域）も楕円形状としてある。これに伴って、レジスト１と電極ランド４との間の隙間の形状も楕円の環状部の形状となっている。 In this figure, not only the electrode land 3 (central region) but also the electrode land 4 (peripheral region) are elliptical. Along with this, the shape of the gap between the resist 1 and the electrode land 4 is also an elliptical annular shape.
　図７は、電極ランドがＳＭＤ構造（Ｓｏｌｄｅｒ　Ｍａｓｋ　Ｄｅｆｉｎｅｄ）を有するものである。図８は、図７の電極ランドの断面図を示したものである。 FIG. 7 shows the electrode land having an SMD structure (Solder Mask Defined). FIG. 8 shows a cross-sectional view of the electrode land of FIG.
　すなわち、これらの図においては、電極ランド４の外周部の一部がレジスト１によって覆われた構造となっている。 That is, in these drawings, a part of the outer peripheral portion of the electrode land 4 is covered with the resist 1.
　図９は、電極ランドがＳＭＤ構造を有し、かつ、楕円形状である例を示したものである。 FIG. 9 shows an example in which the electrode land has an SMD structure and has an elliptical shape.
　この場合の電極ランドの断面形状は、図８に示したものと同様の形状となる。 In this case, the cross-sectional shape of the electrode land is the same as that shown in FIG.
　以上のように、実施例の電極ランドは、ＮＳＭＤ構造だけではなく、ＳＭＤ構造も採用可能である。 As described above, the electrode land of the embodiment can adopt not only the NSMD structure but also the SMD structure.
　次に、実装工程を説明する。 Next, the mounting process will be described.
　図１０Ａ、１０Ｂ及び１０Ｃは、実装工程のフローを示したものである。これらの図は、ＢＧＡを回路基板に設置する工程を表したものである。 10A, 10B and 10C show the flow of the mounting process. These drawings show the process of installing the BGA on the circuit board.
　まず、回路基板の基材２に設けた電極ランド１０１にはんだペースト１１を印刷する（図１０Ａ：印刷工程）。 First, the solder paste 11 is printed on the electrode land 101 provided on the substrate 2 of the circuit board (FIG. 10A: printing process).
　つぎに、ＢＧＡ８（封止樹脂１０で被覆されたＢＧＡ基板６を含む。）のＢＧＡ基板６にあらかじめ付着させたはんだボール１０２をはんだペースト１１の表面に設置する（図１０Ｂ：設置工程）。 Next, the solder balls 102 previously attached to the BGA substrate 6 of the BGA 8 (including the BGA substrate 6 coated with the sealing resin 10) are placed on the surface of the solder paste 11 (FIG. 10B: installation step).
　その後、ＢＧＡ８を設置した回路基板をリフロー炉に入れて加熱し、はんだを溶融させてＢＧＡ８と回路基板とを接合し、実装基板１２とする（図１０Ｃ：リフロー工程）。ここで、リフロー炉の内部は、窒素雰囲気（酸素濃度は、例えば１０００ｐｐｍ以下である。）とする。 Thereafter, the circuit board on which the BGA 8 is installed is heated in a reflow furnace, the solder is melted, the BGA 8 and the circuit board are joined, and the mounting board 12 is obtained (FIG. 10C: reflow process). Here, the inside of the reflow furnace is a nitrogen atmosphere (the oxygen concentration is, for example, 1000 ppm or less).
　リフロー工程においてはんだが溶融した際、はんだの内部にフラックスが残留し、さらにフラックスからガスが発生する。 When the solder melts in the reflow process, flux remains inside the solder, and gas is generated from the flux.
　従来のように、１種類の電極ランドを用いた場合、これらのフラックス及びガスがはんだの外部に抜けずにボイドとして残留し、はんだの接続信頼性が低下する要因となる。 Conventionally, when one type of electrode land is used, these fluxes and gases do not escape to the outside of the solder and remain as voids, which causes a decrease in solder connection reliability.
　一方、実施例においては、はんだボールを設置する電極ランドが２種類の材料を組み合わせたものであり、電極ランドの中央領域と周辺領域とで材料を異ならせてある。そして、〔電極ランド中央領域の成分のＳｎ中での拡散速度（拡散係数）〕＜〔電極ランド周辺領域の成分のＳｎ中での拡散速度（拡散係数）〕又は〔電極ランド中央領域の成分のＳｎ中での拡散速度（拡散係数）〕＞〔電極ランド周辺領域の成分のＳｎ中での拡散速度（拡散係数）〕であるため、リフロー工程におけるはんだ溶融時に、電極ランド中央領域と電極ランド周辺領域とで電極ランドの成分の拡散速度の違いに基づいてはんだ合金内部に流れが発生する。 On the other hand, in the embodiment, the electrode land on which the solder ball is installed is a combination of two kinds of materials, and the material is different in the central region and the peripheral region of the electrode land. Then, [Diffusion rate (diffusion coefficient) of the component of the electrode land central region in Sn] <[Diffusion rate (diffusion coefficient) of the component of the electrode land peripheral region in Sn] or [Component of the component of the electrode land central region] Since the diffusion rate (diffusion coefficient) in Sn >> [diffusion rate (diffusion coefficient) of the component of the electrode land peripheral region in Sn]], when the solder is melted in the reflow process, the electrode land central region and the electrode land periphery A flow is generated inside the solder alloy based on the difference in diffusion rate of the component of the electrode land between the regions.
　このため、はんだ内部に取り残されたフラックス及びフラックスから発生したガスは、はんだ溶融時にはんだの外部へ排出され易く、リフロー後は、ボイドが極めて少ないはんだ接合部を形成することができる。これにより、はんだ接合部の長寿命化や、良好かつ設計値通りの放熱性の確保を実現することが可能となる。 For this reason, the flux left inside the solder and the gas generated from the flux are easily discharged to the outside of the solder when the solder is melted, and after reflowing, a solder joint with very few voids can be formed. As a result, it is possible to extend the life of the solder joints and ensure good heat dissipation as designed.
　図１１～図１３は、電極ランドの変形例を示したものである。 11 to 13 show modified examples of the electrode land.
　図１１は、電極ランドの外形が横長の長方形であって、電極ランド中央領域が略正方形である場合を示す上面図である。 FIG. 11 is a top view showing a case where the outer shape of the electrode land is a horizontally long rectangle and the center area of the electrode land is substantially square.
　本図において、電極ランドの周辺領域を構成する電極ランド４は横長の長方形であり、電極ランドの中央領域を構成する電極ランド３は略正方形である。この電極ランド３、４に接合するはんだは、ボール状（はんだボール）であってもよいし、線状（糸状）であってもよい。 In this figure, the electrode land 4 constituting the peripheral region of the electrode land is a horizontally long rectangle, and the electrode land 3 constituting the central region of the electrode land is substantially square. The solder bonded to the electrode lands 3 and 4 may be ball-shaped (solder ball) or linear (thread-shaped).
　図１２は、電極ランドの外形が横長の長方形であって、電極ランド中央領域が縦長の長方形である場合を示す上面図である。 FIG. 12 is a top view showing a case where the outer shape of the electrode land is a horizontally long rectangle and the center area of the electrode land is a vertically long rectangle.
　本図において、電極ランドの周辺領域を構成する電極ランド４は横長の長方形である。
また、電極ランドの中央領域を構成する電極ランド３は縦長の長方形であり、その端部が電極ランド４の上辺及び下辺に達している。この電極ランド３、４に接合するはんだは、ボール状（はんだボール）であってもよいし、線状（糸状）であってもよい。 In this figure, the electrode land 4 constituting the peripheral region of the electrode land is a horizontally long rectangle.
Further, the electrode land 3 constituting the central region of the electrode land is a vertically long rectangle, and its end portion reaches the upper side and the lower side of the electrode land 4. The solder bonded to the electrode lands 3 and 4 may be ball-shaped (solder ball) or linear (thread-shaped).
　図１３は、電極ランドが縦長の長方形であって、電極ランド中央領域が縦長の長方形である場合を示す上面図である。 FIG. 13 is a top view showing a case where the electrode land is a vertically long rectangle and the center area of the electrode land is a vertically long rectangle.
　本図において、電極ランドの周辺領域を構成する電極ランド４は縦長の長方形である。
また、電極ランドの中央領域を構成する電極ランド３も縦長の長方形であり、その端部が電極ランド４の上辺及び下辺に達している。この電極ランド３、４に接合するはんだは、ボール状（電極ランド３の表面に直線状に配列した複数個のはんだボール）であってもよいし、線状（糸状又は板状）であってもよい。 In this figure, the electrode land 4 constituting the peripheral region of the electrode land is a vertically long rectangle.
Further, the electrode land 3 constituting the central region of the electrode land is also a vertically long rectangle, and its end portion reaches the upper side and the lower side of the electrode land 4. The solder to be joined to the electrode lands 3 and 4 may be ball-shaped (a plurality of solder balls arranged linearly on the surface of the electrode land 3), or may be linear (thread-like or plate-like). Also good.
　図１１～１３においても、電極ランド３、４の中央領域と周辺領域とで成分を異ならせることにより、円形の電極ランドと同様の撹拌作用を生じさせることができる。はんだが線状（糸状）である場合、はんだの側面部に上昇流又は下降流が生じることにより、撹拌作用が生じる。 11 to 13, the same stirring action as that of the circular electrode land can be generated by making the components different between the central region and the peripheral region of the electrode lands 3 and 4. In the case where the solder is linear (thread-like), an agitating action is generated by causing an upward flow or a downward flow in the side surface portion of the solder.
　図１４は、電極ランドとはんだボールとの組み合わせの変形例であって、１か所の電極ランドを４個のはんだボールで接合する場合を示す上面図である。 FIG. 14 is a top view showing a modification of the combination of the electrode land and the solder ball, and shows a case where one electrode land is joined by four solder balls.
　本図においては、電極ランド３、４がともに横長の長方形であり、電極ランド３の長方形の４角にはんだボール５を設置している。この場合、４個のはんだボールが溶融時に合体することにより、１個のはんだとなって電極ランド３、４の中央領域と周辺領域に接し、所望の拡散による流動を生じさせることができる。 In this figure, the electrode lands 3 and 4 are both horizontally long rectangles, and the solder balls 5 are installed at the four rectangular corners of the electrode lands 3. In this case, when the four solder balls are combined at the time of melting, one solder is brought into contact with the central region and the peripheral region of the electrode lands 3 and 4 and a flow due to desired diffusion can be generated.
　図１５Ａ～１５Ｄは、側面部に端子を有する集積回路を回路基板に実装する場合について示したものである。 15A to 15D show a case where an integrated circuit having a terminal on a side surface portion is mounted on a circuit board.
　図１５Ａは、６か所の電極ランドを有する回路基板を示す上面図である。 FIG. 15A is a top view showing a circuit board having six electrode lands.
　本図に示す回路基板は、１個の集積回路に設けた６個の端子を６か所の電極ランド３１に接合するためのものである。 The circuit board shown in this figure is for joining six terminals provided on one integrated circuit to six electrode lands 31.
　本図において、電極ランド３１は、周辺領域を構成する縦長の長方形状の電極ランド４１、及び中央領域を構成する横長の長方形状の電極ランド４２で形成されている。これにより、図１２の場合と同様の撹拌作用を生じさせることができる。 In this figure, the electrode land 31 is formed by a vertically long rectangular electrode land 41 constituting a peripheral region and a horizontally long rectangular electrode land 42 constituting a central region. Thereby, the same stirring action as the case of FIG. 12 can be produced.
　図１５Ｂは、集積回路を回路基板に設置する工程（集積回路設置工程）を示す断面図である。 FIG. 15B is a cross-sectional view showing a process of installing an integrated circuit on a circuit board (integrated circuit installation process).
　本図において、集積回路３３の両側面部には、端子３４が設けてある。一方、回路基板の基材２の電極ランド３１には、はんだペースト３２が塗布（印刷）してある。端子３４と電極ランド３１（はんだペースト３２）とが接するように回路基板の上に集積回路３３を設置する。 In this figure, terminals 34 are provided on both sides of the integrated circuit 33. On the other hand, a solder paste 32 is applied (printed) to the electrode lands 31 of the substrate 2 of the circuit board. The integrated circuit 33 is installed on the circuit board so that the terminal 34 and the electrode land 31 (solder paste 32) are in contact with each other.
　図１５Ｃは、図１５Ｂの集積回路実装工程（集積回路設置工程）を示す上面図である。 FIG. 15C is a top view showing the integrated circuit mounting process (integrated circuit installation process) of FIG. 15B.
　本図において、端子３４は、電極ランド３１に接するように設置される。 In this figure, the terminal 34 is installed in contact with the electrode land 31.
　図１５Ｄは、集積回路を回路基板に接合する工程（集積回路接合工程）を示す断面図である。 FIG. 15D is a cross-sectional view illustrating a process of bonding an integrated circuit to a circuit board (an integrated circuit bonding process).
　本図においては、リフローによってはんだ３５（図１５Ａのはんだペースト３２）が溶融し、端子３４と電極ランド３１とがはんだ付け（接合）されている。はんだ３５は、端子３４の側面部だけでなく、上面部にも付着している。これは、はんだ３５の端子３４の表面に対する濡れ性によるものである。 In this drawing, the solder 35 (the solder paste 32 in FIG. 15A) is melted by reflow, and the terminals 34 and the electrode lands 31 are soldered (joined). The solder 35 is attached not only to the side surface portion of the terminal 34 but also to the upper surface portion. This is due to the wettability of the solder 35 to the surface of the terminal 34.
　図１６は、加熱時のはんだボールの流動状態の一例を示す断面図である。 FIG. 16 is a cross-sectional view showing an example of a solder ball flow state during heating.
　基本的な構成は、図４の電子回路構成部品実装構造と同様である。 The basic configuration is the same as the electronic circuit component mounting structure of FIG.
　加熱時（はんだ溶融時）においては、はんだボール５の内部に電極ランド３、４の成分が溶出し、それぞれの成分の拡散係数及び溶出量の違いによってはんだボール５の内部に流動が生ずる。 During heating (when solder is melted), the components of the electrode lands 3 and 4 are eluted in the solder ball 5, and flow occurs inside the solder ball 5 due to the difference in diffusion coefficient and elution amount of each component.
　本図において、周辺領域を構成する電極ランド４の拡散成分１１１は、中央領域を構成する電極ランド３の拡散成分１１２よりも拡散に起因する流速が速い。このため、液状のはんだボール５の外表面近傍においては、図中上方に向かう流速が速く、液状のはんだボール５の中心軸部分においては、図中下方に向かう流速が速くなる傾向がある。 In this figure, the diffusion component 111 of the electrode land 4 constituting the peripheral region has a faster flow velocity due to the diffusion than the diffusion component 112 of the electrode land 3 constituting the central region. For this reason, in the vicinity of the outer surface of the liquid solder ball 5, the flow velocity going upward in the figure tends to be high, and in the central axis portion of the liquid solder ball 5, the flow velocity going downward in the figure tends to be high.
　すなわち、電極ランド３の成分に比べて電極ランド４の成分の拡散係数が大きい場合、又は、電極ランド４の成分の溶出量が多い場合に、これらの成分の拡散に伴う流動によって液状のはんだボール５の内部における撹拌が促進される。 That is, when the diffusion coefficient of the component of the electrode land 4 is larger than that of the component of the electrode land 3 or when the amount of elution of the component of the electrode land 4 is large, the liquid solder ball is caused by the flow accompanying the diffusion of these components. Stirring inside 5 is promoted.
　図１７は、加熱時のはんだボールの流動状態の他の例を示す断面図である。 FIG. 17 is a cross-sectional view showing another example of a solder ball flow state during heating.
　本図の場合、中央領域からの拡散の影響が大きくなっている。 In the case of this figure, the influence of diffusion from the central region is large.
　本図において、中央領域を構成する電極ランド３の拡散成分１１２は、周辺領域を構成する電極ランド４の拡散成分１１１よりも拡散に起因する流速が速い。このため、液状のはんだボール５の外表面近傍においては、図中下方に向かう流速が速く、液状のはんだボール５の中心軸部分においては、図中上方に向かう流速が速くなる傾向がある。 In this figure, the diffusion component 112 of the electrode land 3 constituting the central region has a higher flow velocity due to the diffusion than the diffusion component 111 of the electrode land 4 constituting the peripheral region. For this reason, in the vicinity of the outer surface of the liquid solder ball 5, the flow velocity going downward in the figure tends to be fast, and in the central axis portion of the liquid solder ball 5, the flow velocity going upward in the figure tends to be high.
　すなわち、電極ランド４の成分に比べて電極ランド３の成分の拡散係数が大きい場合、又は、電極ランド３の成分の溶出量が多い場合に、これらの成分の拡散に伴う流動によって液状のはんだボール５の内部における撹拌が促進される。 That is, when the diffusion coefficient of the component of the electrode land 3 is larger than the component of the electrode land 4 or when the amount of elution of the component of the electrode land 3 is large, the liquid solder ball is caused by the flow accompanying the diffusion of these components. Stirring inside 5 is promoted.
　はんだが線状（糸状）である場合も、はんだの断面を図示すると、図１６及び１７に示すようになる。したがって、ボール状のはんだ（はんだボール）の場合と同様の撹拌作用が生じることになる。 Also when the solder is linear (thread-like), the cross section of the solder is shown in FIGS. 16 and 17. Therefore, the same stirring action as in the case of ball-shaped solder (solder ball) occurs.
　次に、実施例の電極ランドの成分について具体的に説明する。 Next, the components of the electrode land of the example will be specifically described.
　電極ランド３（中央領域）の材料がニッケル（Ｎｉ）を主成分とする合金であって、電極ランド４（周辺領域）の材料が金（Ａｕ）を主成分とする合金である場合、同一温度において、〔ＮｉのＳｎ中での拡散速度（拡散係数）〕＜〔ＡｕのＳｎ中での拡散速度（拡散係数）〕となる。 When the material of the electrode land 3 (central region) is an alloy containing nickel (Ni) as a main component and the material of the electrode land 4 (peripheral region) is an alloy containing gold (Au) as a main component, the same temperature [Diffusion rate of Ni in Sn (diffusion coefficient)] <[Diffusion rate of Au in Sn (diffusion coefficient)].
　また、ＮｉとＡｕとではＳｎとの共晶温度が異なり、ＮｉとＳｎとの共晶温度は２２１℃であり、ＡｕとＳｎとの共晶温度は２８０℃である。 Also, the eutectic temperature of Sn is different between Ni and Au, the eutectic temperature of Ni and Sn is 221 ° C., and the eutectic temperature of Au and Sn is 280 ° C.
　電極ランド３（中央領域）の材料がニッケル（Ｎｉ）を主成分とする合金であって、電極ランド４（周辺領域）の材料が銅（Ｃｕ）を主成分とする合金である場合、同一温度において、〔ＮｉのＳｎ中での拡散速度（拡散係数）〕＜〔ＣｕのＳｎ中での拡散速度（拡散係数）〕となる。 When the material of the electrode land 3 (central region) is an alloy containing nickel (Ni) as a main component and the material of the electrode land 4 (peripheral region) is an alloy containing copper (Cu) as a main component, the same temperature [Diffusion rate of Ni in Sn (diffusion coefficient)] <[Diffusion rate of Cu in Sn (diffusion coefficient)].
　また、ＮｉとＣｕとではＳｎとの共晶温度が異なり、ＮｉとＳｎとの共晶温度は２２１℃であり、ＣｕとＳｕとの共晶温度は２２７℃である。 Also, the eutectic temperature of Sn is different between Ni and Cu, the eutectic temperature of Ni and Sn is 221 ° C., and the eutectic temperature of Cu and Su is 227 ° C.
　電極ランド３（中央領域）の材料が銅（Ｃｕ）を主成分とする合金であって、電極ランド４（周辺領域）の材料が金（Ａｕ）を主成分とする合金である場合、同一温度において、〔ＣｕのＳｎ中での拡散速度（拡散係数）〕＜〔ＡｕのＳｎ中での拡散速度（拡散係数）〕となる。 When the material of the electrode land 3 (central region) is an alloy containing copper (Cu) as a main component and the material of the electrode land 4 (peripheral region) is an alloy containing gold (Au) as a main component, the same temperature [Diffusion rate of Cu in Sn (diffusion coefficient)] <[Diffusion rate of Au in Sn (diffusion coefficient)].
　また、ＣｕとＡｕとではＳｎとの共晶温度が異なり、ＣｕとＳｎとの共晶温度は２２７℃であり、ＡｕとＳｕとの共晶温度は２８０℃である。 Also, the eutectic temperature of Sn is different between Cu and Au, the eutectic temperature of Cu and Sn is 227 ° C., and the eutectic temperature of Au and Su is 280 ° C.
　本発明によれば、ＢＧＡ等のはんだ接合部におけるはんだ内部のフラックス及びボイドが極めて少ない電子回路構成部品実装構造を実現することができ、はんだの接合信頼性を向上させることができる。 According to the present invention, it is possible to realize an electronic circuit component mounting structure in which solder flux and voids in a solder joint such as a BGA are extremely small, and the solder joint reliability can be improved.
　特に、自動車に搭載するコントロールユニットにおいては、１０年或いはそれ以上の長い寿命が求められており、はんだ接合部の接合信頼性が非常に重要となる。本発明によれば、はんだの破壊進行を促進することが懸念されるはんだ内部のボイドやフラックスが極めて少ないため、はんだの接合長寿命化を図ることが可能となる。 In particular, a control unit mounted on an automobile is required to have a long life of 10 years or more, and the bonding reliability of the solder joint is very important. According to the present invention, since there are very few voids and flux inside the solder, which are likely to promote the progress of solder breakage, it is possible to extend the life of the solder joint.
　また、自動車に搭載するコントロールユニットのように使用環境の温度条件が非常に厳しい製品の場合、ボイドが残存すると、ボイドの内部の空気等が膨張収縮を繰り返すため、はんだ接合部の疲労破壊が生じやすくなる。パワーモジュールのように放熱量を大きくする必要がある製品の場合、はんだ接合部を介して放熱量を確保するため、はんだ内部のボイドを低減することが必須となる。 In addition, in the case of products with extremely severe temperature conditions such as control units installed in automobiles, if voids remain, the air inside the voids repeatedly expands and contracts, causing fatigue failure of the solder joints. It becomes easy. In the case of a product that requires a large amount of heat dissipation, such as a power module, it is essential to reduce voids inside the solder in order to ensure the amount of heat dissipation through the solder joint.
　本発明によれば、放熱を妨げるボイドが極めて少ないため、設計値通りの放熱量を確保することが可能となる。 According to the present invention, since there are very few voids that hinder heat dissipation, it is possible to secure a heat dissipation amount as designed.
　さらに、携帯電話やデジタルカメラ等小型化が急速に進む民生機器の場合、ＢＧＡはんだ接合部の電極ランドの直径が小さくなり、電極ランドのピッチも狭くなってきている。
このため、はんだ内部のボイドがはんだ接合の信頼性にこれまで以上に影響してくる。 Furthermore, in the case of consumer devices such as mobile phones and digital cameras that are rapidly becoming smaller in size, the diameter of electrode lands at the BGA solder joints has become smaller, and the pitch between the electrode lands has also become narrower.
For this reason, voids inside the solder affect the reliability of solder joints more than ever.
　本発明によれば、はんだ内部のボイドが極めて少ないため、電極ランドの小径化や狭ピッチ化に対応する信頼の高いはんだ接合を実現することができる。 According to the present invention, since there are very few voids inside the solder, it is possible to realize a highly reliable solder joint corresponding to the reduction in the diameter and pitch of the electrode land.
　１：レジスト、２：基材、３、４：電極ランド、５：はんだボール、６：ＢＧＡ基板、７：レジスト、８：ＢＧＡ、９：はんだ接合部、１０：封止樹脂、１１：はんだペースト、１２：実装基板、２１：端子、２２：ＢＧＡ、３１：電極ランド、３２：はんだペースト、３３：集積回路、３４：端子、３５：はんだ、１０１：電極ランド、１０２：はんだボール、１１１、１１２：拡散成分。 1: resist 2, base material 3, 4: electrode land, 5: solder ball, 6: BGA substrate, 7: resist, 8: BGA, 9: solder joint, 10: sealing resin, 11: solder paste , 12: mounting substrate, 21: terminal, 22: BGA, 31: electrode land, 32: solder paste, 33: integrated circuit, 34: terminal, 35: solder, 101: electrode land, 102: solder ball, 111, 112 : Diffusion component.

Claims (14)

  1. 　回路基板の基材の表面に設けた電極ランドと、端子を有し前記回路基板に実装する電子回路構成部品と、前記電極ランドと前記端子とを電気的に接続するはんだとを含む電子回路構成部品実装構造であって、前記電極ランドは、その表面の中央領域とその周辺領域とで成分が異なることを特徴とする電子回路構成部品実装構造。 An electronic circuit configuration including an electrode land provided on a surface of a substrate of a circuit board, an electronic circuit component having a terminal and mounted on the circuit board, and solder for electrically connecting the electrode land and the terminal An electronic circuit component mounting structure, wherein the electrode land has a component different between a central region and a peripheral region of the electrode land.
  2. 　前記中央領域の成分の前記はんだの内部における物質伝達速度は、前記周辺領域の成分の前記はんだの内部における物質伝達速度に比べて小さいことを特徴とする請求項１記載の電子回路構成部品実装構造。 2. The electronic circuit component mounting structure according to claim 1, wherein a material transfer rate of the component in the central region inside the solder is smaller than a material transfer rate of the component in the peripheral region in the solder. .
  3. 　前記中央領域の成分の前記はんだの内部における物質伝達速度は、前記周辺領域の成分の前記はんだの内部における物質伝達速度に比べて大きいことを特徴とする請求項１記載の電子回路構成部品実装構造。 2. The electronic circuit component mounting structure according to claim 1, wherein a material transfer rate of the component in the central region inside the solder is larger than a material transfer rate of the component in the peripheral region in the solder. .
  4. 　前記はんだは、スズを含むことを特徴とする請求項１～３のいずれか一項に記載の電子回路構成部品実装構造。 The electronic circuit component mounting structure according to any one of claims 1 to 3, wherein the solder contains tin.
  5. 　温度が等しい場合に、前記中央領域の成分がスズ中に拡散する際の拡散係数は、前記周辺領域の成分がスズ中に拡散する際の拡散係数に比べて小さいことを特徴とする請求項４記載の電子回路構成部品実装構造。 5. The diffusion coefficient when the components in the central region diffuse into tin when the temperatures are equal is smaller than the diffusion coefficient when the components in the peripheral region diffuse into tin. The electronic circuit component mounting structure described.
  6. 　温度が等しい場合に、前記中央領域の成分がスズ中に拡散する際の拡散係数は、前記周辺領域の成分がスズ中に拡散する際の拡散係数に比べて大きいことを特徴とする請求項４記載の電子回路構成部品実装構造。 5. The diffusion coefficient when the components in the central region diffuse into tin when the temperature is equal is larger than the diffusion coefficient when the components in the peripheral region diffuse into tin. The electronic circuit component mounting structure described.
  7. 　前記中央領域の成分の前記はんだへの前記中央領域の単位面積当たりの溶出量は、前記周辺領域の成分の前記はんだへの前記周辺領域の単位面積当たりの溶出量に比べて小さいことを特徴とする請求項１記載の電子回路構成部品実装構造。 The amount of elution per unit area of the central region of the component of the central region into the solder is smaller than the amount of elution per unit area of the peripheral region of the component of the peripheral region into the solder. The electronic circuit component mounting structure according to claim 1.
  8. 　前記中央領域の成分の前記はんだへの前記中央領域の単位面積当たりの溶出量は、前記周辺領域の成分の前記はんだへの前記周辺領域の単位面積当たりの溶出量に比べて大きいことを特徴とする請求項１記載の電子回路構成部品実装構造。 The amount of elution per unit area of the central region of the component of the central region into the solder is larger than the amount of elution per unit area of the peripheral region of the component of the peripheral region into the solder. The electronic circuit component mounting structure according to claim 1.
  9. 　前記中央領域の面積は、前記電極ランド全体の面積の２５分の１～４分の１であることを特徴とする請求項１～８のいずれか一項に記載の電子回路構成部品実装構造。 The electronic circuit component mounting structure according to any one of claims 1 to 8, wherein an area of the central region is 1/25 to 1/4 of an area of the entire electrode land.
  10. 　前記中央領域の高さは、前記周辺領域の高さよりも高いことを特徴とする請求項１～９のいずれか一項に記載の電子回路構成部品実装構造。 10. The electronic circuit component mounting structure according to claim 1, wherein a height of the central region is higher than a height of the peripheral region.
  11. 　前記電子回路構成部品は、ボールグリッドアレイであり、前記はんだは、前記ボールグリッドアレイのはんだボールであることを特徴とする請求項１～１０のいずれか一項に記載の電子回路構成部品実装構造。 11. The electronic circuit component mounting structure according to claim 1, wherein the electronic circuit component is a ball grid array, and the solder is a solder ball of the ball grid array. .
  12. 　請求項１～１１のいずれか一項に記載の電子回路構成部品実装構造を有することを特徴とする実装基板。 A mounting board comprising the electronic circuit component mounting structure according to any one of claims 1 to 11.
  13. 　請求項１２記載の実装基板を含むことを特徴とする半導体装置。 A semiconductor device comprising the mounting substrate according to claim 12.
  14. 　請求項１３記載の半導体装置を含むことを特徴とする電子機器。 An electronic apparatus comprising the semiconductor device according to claim 13.
PCT/JP2011/060345 2010-05-07 2011-04-28 Structure for mounting electronic circuit configuration component WO2011138921A1 (en)

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JP2004047510A (en) * 2002-07-08 2004-02-12 Fujitsu Ltd Electrode structure and its forming method
JP2006216766A (en) * 2005-02-03 2006-08-17 Toshiba Corp Ceramics wiring board and semiconductor device using it
JP2008042071A (en) * 2006-08-09 2008-02-21 Matsushita Electric Ind Co Ltd Electroless plating method

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Publication number Priority date Publication date Assignee Title
JP2004047510A (en) * 2002-07-08 2004-02-12 Fujitsu Ltd Electrode structure and its forming method
JP2006216766A (en) * 2005-02-03 2006-08-17 Toshiba Corp Ceramics wiring board and semiconductor device using it
JP2008042071A (en) * 2006-08-09 2008-02-21 Matsushita Electric Ind Co Ltd Electroless plating method

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