JP2014053597A - Chip type electronic component and connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chip type electronic component of which excellent connection can be achieved by suppressing warpage of a substrate during flip-chip mounting, and to provide a connection structure thereof.SOLUTION: In a chip type electronic component 1, a passivation film 6 having a thickness satisfying a relation Hb>Hp≥(1/3)Hb is formed in a region where bump electrodes 4, 5 are not arranged on the mounting surface 2a of a substrate 2. Consequently, in a connection structure 30, volume difference of an anisotropic conductive adhesive can be suppressed between a region where the bump electrodes 4, 5 are arranged and a region where the bump electrodes are not arranged, and thereby warpage of the substrate 2 due to the difference in cure shrinkage amount of the anisotropic conductive adhesive can be suppressed during flip-chip mounting. Since warpage of the substrate 2 can be suppressed, peeling of the bump electrodes 4, 5, arranged along the long side of the substrate 2, off from an electrode 22 can be avoided, and excellent connection state can be maintained.

Description

  The present invention relates to a chip-type electronic component and a connection structure.

  With the downsizing and thinning of electronic devices, establishment of high-density mounting technology for chip-type electronic components is required. As a conventional chip mounting method, for example, there is a method using a lead frame. In this conventional method, the chip on the lead frame is connected to the circuit board with a wire to perform resin sealing, but it is difficult to improve the mounting density because of securing the wire space. .

  Therefore, in recent years, flip-chip mounting has attracted attention as a technology that enables high-density mounting of chip-type electronic components. In this method, the bump electrode on the chip side and the electrode on the circuit board side are connected using an anisotropic conductive adhesive or the like. For example, in the method described in Patent Document 1, when connecting the bump electrode and the electrode on the circuit board with an anisotropic conductive adhesive, an ultrasonic wave is applied to the connection portion in advance to melt the metal and ensure connectivity. doing.

JP2010-251789

  By the way, in the flip chip mounting method as described above, after an anisotropic conductive adhesive is disposed between the bump electrode on the chip side and the electrode on the circuit board side, light or heat is applied to the anisotropic conductive adhesive. In addition, a curing step may be included. In this process, curing shrinkage of the anisotropic conductive adhesive occurs, but the thickness of the anisotropic conductive adhesive is different between the area where the bump electrode is formed and the area where the bump electrode is not formed on the chip. Differences in quantity may occur. For this reason, there is a possibility that the substrate of the chip is warped toward the region where the amount of cure shrinkage is large, that is, the region where the bump electrode is not formed. Such a problem is particularly noticeable when the substrate is thin. When the substrate is warped, a problem of poor connection between the chip-type electronic component and the circuit substrate becomes a problem.

  The present invention has been made to solve the above problems, and provides a chip-type electronic component capable of realizing good connection by suppressing warpage of the substrate during flip-chip mounting, and a connection structure thereof. With the goal.

  A chip-type electronic component according to the present invention includes a substrate, a bump electrode arranged on one side of the substrate, and a passivation film formed along the arrangement direction of the bump electrode on the one side of the substrate. The electronic component is characterized in that the thickness Hp of the passivation film and the thickness Hb of the bump electrode satisfy Hb> Hp ≧ (1/3) Hb.

  In this chip-type electronic component, a passivation film having a thickness satisfying the above relationship is formed in a region where the bump electrodes are not arranged. With this passivation film, when flip chip mounting a chip-type electronic component, it is possible to reduce the volume difference of the anisotropic conductive adhesive between the region where the bump electrodes are arranged and the region where the bump electrodes are not arranged. This makes it possible to suppress the warpage of the substrate due to the difference in the amount of cure shrinkage of the anisotropic conductive adhesive. Further, it is possible to prevent the passivation film from being damaged by foreign matters during mounting. Thereby, a favorable connection is realizable.

  Further, the passivation film preferably extends between the rows of bump electrodes. In this case, it is possible to further suppress the warpage of the substrate due to the difference in the curing shrinkage amount of the anisotropic conductive adhesive.

  The thickness of the passivation film is preferably 3 μm or more. In this case, the space into which the foreign substance enters is reduced, and the entry of the foreign substance can be prevented. Therefore, damage to the passivation film due to foreign substances is suppressed, and the function of the passivation film as a protective film can be maintained.

  The chip-type electronic component preferably has a thickness not including the bump electrode of 0.3 mm or less. In a thin chip-type electronic component having a thickness of 0.3 mm or less, warpage of the substrate due to curing shrinkage of the anisotropic conductive adhesive tends to occur remarkably. Therefore, by setting the thickness of the passivation film and the thickness of the bump electrode in the above relationship, the warpage of the substrate can be effectively suppressed even in a thin chip type electronic component.

  The connection structure according to the present invention is characterized in that the bump electrode of the chip-type electronic component is connected to the electrode of the circuit board through a cured product of anisotropic conductive adhesive.

  In this connection structure, in the chip-type electronic component, the thickness of the passivation film and the thickness of the bump electrode satisfy the above relationship. Therefore, when flip-chip mounting the chip-type electronic component, it becomes possible to reduce the volume difference of the anisotropic conductive adhesive between the region where the bump electrode is arranged and the region where the bump electrode is not arranged, The board | substrate curvature by the difference in the amount of cure shrinkage of an anisotropic conductive adhesive can be suppressed. Further, it is possible to prevent the passivation film from being damaged by foreign matters during mounting. Thereby, a good connection can be realized.

  According to the present invention, good connection can be realized by suppressing the warpage of the substrate during flip chip mounting.

1 is a schematic plan view showing a chip-type electronic component according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view taken along line II-II in FIG. 1. It is a typical sectional view showing the connection structure concerning one embodiment of the present invention. It is typical sectional drawing which shows the connection structure which concerns on a comparative example.

  Hereinafter, preferred embodiments of a chip-type electronic component and a connection structure according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic plan view showing a chip-type electronic component 1 according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view taken along the line II-II in FIG. As shown in FIGS. 1 and 2, the chip-type electronic component 1 includes a substrate 2, bump electrodes 4 and 5, and a passivation film 6. The chip-type electronic component 1 is an IC chip or a circuit board that is applied to an electronic device such as a touch panel, for example, and is connected to a circuit board 20 described later to form a connection structure 30.

  The substrate 2 is a semiconductor substrate having a rectangular shape, for example. The thickness of the substrate 2 is, for example, about 0.1 to 1.1 mm. There is no restriction | limiting in particular as a semiconductor, Various semiconductors, such as elemental semiconductors, such as silicon and germanium, and compound semiconductors, such as gallium arsenide and indium phosphorus, can be used. One surface side of the substrate 2 is a mounting surface 2a for the circuit substrate 20, and bump electrodes 4 and 5 and a passivation film 6 are arranged. In addition, the shape of the board | substrate 2 is not restricted to a rectangular shape, Square shape, trapezoid shape, etc. may be sufficient.

  The bump electrodes 4 and 5 are formed on connection terminals (not shown) provided on the mounting surface 2 a of the substrate 2. The bump electrodes 4 are arranged in a staggered pattern along one long side of the substrate 2. The bump electrodes 5 are arranged in a line along the other long side of the substrate 2. The passivation film 6 is formed in a flat rectangular parallelepiped shape along the arrangement direction of the bump electrodes 4, 5 in the region between the bump electrode 4 and the bump electrode 5.

  When the substrate 2 is a circuit board, the connection terminal may be formed at the same time as the wiring conductor, or may be formed by removing unnecessary portions of a metal foil such as a copper foil by etching. Further, it may be formed on the insulating substrate by electroless plating in accordance with the shape of the connection terminal. On the other hand, the connection terminal is made of aluminum, for example, when the substrate 2 is a semiconductor substrate. In this case, noble metal plating with nickel, gold, platinum or the like may be performed on the surface of the connection terminal.

  The bump electrodes 4 and 5 are electrodes used for connection to the circuit board 20 and are formed of, for example, nickel or gold bumps or solder balls. The bump electrodes 4 and 5 may be formed by solder bumps, copper bumps, bumps having a structure in which a solder or tin layer is formed at the tip of a copper pillar, gold bumps, or the like. Moreover, you may use the bump of the structure in which the solder or the tin layer was formed in the copper bump or the copper pillar tip from the correspondence to fine connection. In addition, about the number and position of bump electrode 4 and 5, it can select suitably according to a use and a use purpose. The cross-sectional shape of the bump electrodes 4 and 5 can also be selected as appropriate.

  As a method for forming the bump electrodes 4 and 5, a general-purpose method such as etching or plating can be used. For example, a conductor portion other than the formation location of the bump electrodes 4 and 5 is half-etched in the thickness direction to form a projection portion, and the other portion is etched away while leaving the circuit portion of the thinner conductor portion. Bump electrodes 4 and 5 can be formed. Further, after forming a circuit on the mounting surface 2a of the substrate 2, the bump electrodes 4 and 5 may be formed by a method in which only the connection terminal portions are thickened by plating.

  The thickness Hb of the bump electrodes 4 and 5 is not particularly limited, but is, for example, 9 to 18 μm. Note that the thickness Hb of the bump electrodes 4 and 5 can be adjusted in the above bump forming method, and the thickness Hb can be measured using an existing film thickness measuring apparatus. Further, dummy bumps (not shown) may be further formed outside the region where the bump electrodes 4 and 5 are arranged. When dummy bumps are formed in the region, flip chip mounting is facilitated in a state where the posture of the chip electronic component 1 is parallel to the circuit board 20 on which the chip electronic component 1 is mounted. Thereby, the workability of mounting can be improved.

  On the other hand, the passivation film 6 is a protective film that prevents intrusion of moisture, oxygen, and the like from the outside. For example, using a silicon nitride, silicon oxide, or the like, a known film forming method such as CVD, vapor deposition, or sputtering is used. Is formed. In the present embodiment, the passivation film 6 is formed in a long shape between the bump electrodes 4, 5 of the substrate 2, but the passivation film 6 is not limited to a long shape, and a rectangular passivation film is used as the bump electrode 4. You may make it interspersed between five. Further, the passivation film 6 may be arranged not in the area between the bump electrodes 4 and 5 but in a region outside the bump electrodes 4 and 5 depending on the arrangement position of the bump electrodes 4 and 5.

  The thickness Hp of the passivation film 6 satisfies Hb> Hp ≧ (1/3) Hb with respect to the thickness Hb of the bump electrodes 4 and 5. The thickness Hp of the passivation film 6 is, for example, 3 μm or more when Hb is 9 μm, 4 μm or more when Hb is 12 μm or more, and 6 μm or more when Hb is 18 μm. Further, in relation to the substrate 2, the thickness Hp of the passivation film 6 is determined so that the thickness of the chip-type electronic component 1 excluding the thickness of the bump electrodes 4 and 5 is 0.3 mm or less. That is, the sum of the thickness of the passivation film 6 and the thickness of the substrate 2 is determined to be 0.3 mm or less. In this case, the thickness of the substrate 2 is set to be less than 0.3 mm. The thickness Hp of the passivation film 6 can be adjusted in the above-described passivation film forming method, and the thickness Hp can be measured using an existing film thickness measuring apparatus.

  Subsequently, a connection structure using the chip-type electronic component 1 described above will be described.

  FIG. 3 is a schematic cross-sectional view showing a connection structure according to an embodiment of the present invention. As shown in the figure, the connection structure 30 is a structure in which the chip-type electronic component 1 and the circuit board 20 are flip-chip connected via a cured product 10 of anisotropic conductive adhesive.

  The circuit board 20 is, for example, a glass substrate 24 having electrodes 22 on the surface. As the glass substrate 24, for example, coning glass or soda glass can be used. The shape of the glass substrate 24 is assumed to be a rectangle, but a square, a trapezoid, or the like can be appropriately selected according to the shape of the chip electronic component 1. The circuit board 20 is not limited to a glass substrate, and a normal circuit board, a flexible printed wiring board, a semiconductor chip, or the like may be used. In the case of a circuit board, an unnecessary part of a metal layer such as copper formed on the surface of an insulating substrate such as glass epoxy, polyimide, polyester, or ceramic is removed by etching to form a wiring pattern, or the surface of the insulating substrate is plated with copper. For example, a wiring pattern may be formed by using a conductive material printed on the surface of an insulating substrate.

  The electrode 22 is formed on the glass substrate 24 so as to correspond to the positions of the bump electrodes 4 and 5 provided in the chip-type electronic component 1. As the electrode 22, for example, a transparent electrode made of indium tin oxide (ITO) can be used. As the transparent electrode, indium zinc oxide (IZO) or the like may be used. As a method for forming the transparent electrode, a known method such as a sputtering method or an electron beam method can be used. Further, as the electrode 22, an electrode made of aluminum, chromium, silver, or the like may be formed on the glass substrate 24.

  The anisotropic conductive adhesive contains a resin composition 12 that is cured by heat or light, and conductive particles 14. As the resin constituting the resin composition 12, for example, a thermoplastic resin, a thermosetting resin, a mixed system of a thermoplastic resin and a thermosetting resin, or a photocurable resin is used. As the thermoplastic resin, there are a styrene resin type and a polyester resin type, and as the thermosetting resin, an epoxy resin type and a silicone resin type are known. When a thermoplastic resin or a thermosetting resin is used, heating and pressing are usually required. This is because the thermoplastic resin allows the resin to flow to obtain adhesion to the adherend, and the thermosetting resin further performs a resin curing reaction. Moreover, when using a photocurable resin, it is useful when the connection at low temperature is calculated | required. Since the photocurable resin does not require heating for curing, it is preferable because warpage of the chip type electronic component 1 due to a difference in thermal expansion coefficient between the chip type electronic component 1 and the glass substrate 24 is suppressed.

  As the conductive particles 14, for example, metal particles such as Au, Ag, Ni, Cu, Pd, solder, and carbon particles are used. Further, the conductive particles 14 may be those in which the surface of a transition metal such as Ni or Cu is coated with a noble metal such as Au or Pd. In addition, a conductive layer is formed on the surface of non-conductive particles by a method such as coating the surface of non-conductive particles such as glass, ceramic, and plastic with a conductive material, and the outermost layer is made of noble metals. In the case of using hot-melt metal particles, since it has deformability by heating and pressing, the contact area with the electrode increases at the time of connection, and the reliability can be improved.

  The connection structure 30 can be obtained by the following method. That is, the connection structure 30 aligns the bump electrodes 4 and 5 on the chip-type electronic component 1 side with the electrode 22 on the circuit board 20 side, and anisotropically conductive between the bump electrodes 4 and 5 and the electrode 22. With the adhesive interposed, the anisotropic conductive adhesive is cured by heat or light while pressing the chip-type electronic component 1 and the circuit board 20 to obtain a cured product 10 of the anisotropic conductive adhesive. Formed by.

  At this time, in the chip-type electronic component 1, as described above, the thickness satisfying Hb> Hp ≧ (1/3) Hb in the region where the bump electrodes 4 and 5 are not arranged on the mounting surface 2a of the substrate 2. The passivation film 6 is formed. The thickness of the passivation film 6 is 3 μm or more. Therefore, in the connection structure 30, the volume difference of the anisotropic conductive adhesive between the region where the bump electrodes 4 and 5 are arranged and the region where the bump electrodes 4 and 5 are not arranged can be suppressed. Warpage of the substrate 2 due to the difference in curing shrinkage of the anisotropic conductive adhesive can be suppressed. Since the warpage of the substrate 2 can be suppressed, it is possible to avoid the bump electrodes 4 and 5 arranged along the long side of the substrate 2 from being peeled off from the electrode 22 and maintain a good connection state. The connection state can be evaluated, for example, by measuring the connection resistance between the bump electrodes 4 and 5 and the electrode 22.

  Further, in the chip-type electronic component 1, foreign matter is unlikely to enter between the bump electrodes 4, 5, so that the passivation film 6 can be prevented from being damaged by foreign matter during mounting. Thereby, a favorable connection can be realized more reliably. Even in such a thin chip-type electronic component 1, the warp of the substrate 2 can be sufficiently suppressed by providing the passivation film 6 having a thickness satisfying the above relationship between the bump electrodes 4 and 5.

  FIG. 4 is a schematic cross-sectional view showing a connection structure according to a comparative example. As shown in the figure, in the connection structure 100 according to the comparative example, the passivation film 6 is not formed between the bump electrodes 4 and 5 (or a passivation film satisfying Hp <(1/3) Hb is formed. ) Is different from the connection structure 30 according to the present embodiment. In this connection structure 100, compared with the connection structure 30, the volume difference of the anisotropic conductive adhesive is large between the area where the bump electrodes 4 and 5 are arranged and the area where the bump electrodes 4 and 5 are not arranged.

  Therefore, in the connection structure 100, when flip chip mounting is performed, the amount of cure shrinkage of the anisotropic conductive adhesive in the region where the bump electrodes 4 and 5 are not arranged is in the region where the bump electrodes 4 and 5 are arranged. The warpage of the substrate 2 occurs so as to be larger, for example, convex toward the circuit substrate 20 side. For this reason, there is a possibility that the bump electrodes 4 and 5 and the electrode 22 are separated from each other and connection failure occurs. Therefore, as in the present embodiment, it is useful to form the passivation film 6 having a thickness satisfying Hb> Hp ≧ (1/3) Hb from the viewpoint of suppressing connection failure due to the warpage of the substrate.

  DESCRIPTION OF SYMBOLS 1 ... Chip-type electronic component, 2 ... Board | substrate, 4, 5 ... Bump electrode, 6 ... Passivation film | membrane, 10 ... Hardened | cured material of anisotropic conductive adhesive, 20 ... Circuit board, 22 ... Electrode, 30 ... Connection structure.

Claims (5)

A chip-type electronic component comprising: a substrate; a bump electrode arranged on one side of the substrate; and a passivation film formed along the arrangement direction of the bump electrode on the one side of the substrate,
A chip-type electronic component, wherein the thickness Hp of the passivation film and the thickness Hb of the bump electrode satisfy Hb> Hp ≧ (1/3) Hb.   The chip-type electronic component according to claim 1, wherein the passivation film extends between the bump electrode rows.   The chip-type electronic component according to claim 1, wherein a thickness Hp of the passivation film is 3 μm or more.   4. The chip-type electronic component according to claim 1, wherein the thickness of the chip-type electronic component not including the bump electrode is 0.3 mm or less. 5.   5. A connection structure, wherein the bump electrode of the chip-type electronic component according to claim 1 is connected to an electrode of a circuit board through a cured product of an anisotropic conductive adhesive.

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