JP2010245558A - Electro-optical device and electronic module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mounting structure of an electronic component, improving reliability of a conductive connection state by raising joining strength between bump electrodes and terminals on a side of a board. <P>SOLUTION: In a mounting structure of an electronic component, the electronic component 121 having bump electrodes 12 is mounted on a board 111 having terminals 11. Each of the bump electrodes 12 has a structure having a core formed of an internal resin 13 and its surface covered with a conductive film 14. Each of the bump electrodes 12 is elastically deformed along the shape of at least one corner 11c of each of the terminals 11, and thereby, the conductive film 14 is directly brought into conductive contact with at least a portion of an upper surface 11a of each of the terminals 11 and at least a portion of a surface (side surface 11b) corresponding to a thickness direction of each of the terminals 11. The board 111 and the electronic component 121 are equipped with a holding means for holding a state where each of the bump electrodes 12 is elastically deformed to be brought into conductive contact with each of the terminals. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electronic component mounting structure.

  2. Description of the Related Art Conventionally, in circuit boards and liquid crystal display devices mounted on various electronic devices, a technique for mounting an electronic component such as a semiconductor IC on the substrate is used. For example, a liquid crystal driving IC chip for driving a liquid crystal panel is mounted on the liquid crystal display device. The liquid crystal driving IC chip may be directly mounted on a glass substrate constituting the liquid crystal panel, or may be mounted on a flexible substrate (FPC) mounted on the liquid crystal panel. The former mounting structure is called a COG (Chip On Glass) structure, and the latter is called a COF (Chip On FPC) structure. In addition to these mounting structures, for example, a COB (Chip On board) structure in which an IC chip is mounted on a glass epoxy substrate or the like is also known.

  On the substrate used in such a mounting structure, lands (terminals) connected to the wiring pattern are formed, while on the electronic component, bump electrodes for obtaining electrical connection are formed. The electronic component mounting structure is formed by mounting the electronic component on the substrate in a state where the bump electrode is connected to the land.

By the way, in the mounting structure described above, it is desired that the electronic component is more firmly and securely connected on the substrate. In particular, when there are a plurality of lands and bump electrodes, and a plurality of lands and bump electrodes are connected to each other, all the lands and bump electrodes are connected well to ensure reliability. It has become important.
However, in general, lands and bump electrodes are made of metal. Therefore, when a misalignment occurs at the time of joining, or when a misalignment occurs between them due to poor position accuracy of the land or bump electrode, these lands and bump electrodes are formed. Insufficient bonding strength is obtained between the bump electrode and the bump electrode, which may cause a contact failure (conductivity failure).
In addition, the distance between the land and the bump electrode is not constant due to warpage of electronic parts such as a substrate and IC, and variations in the formation height of the land and the bump electrode, and sufficient bonding between the land and the bump electrode is possible. The strength could not be obtained, and there was a risk of causing poor contact (conductive failure).

Conventionally, in order to prevent such inconvenience, a printed wiring having a conductor pattern having a trapezoidal cross section, forming a metal conductive layer on the conductor pattern, and providing a number of irregularities on the surface of the metal conductive layer A plate is provided (see, for example, Patent Document 1).
According to this printed wiring board, due to the anchor effect due to the unevenness of the surface of the metal conductive layer, the connection electrode of the component (electronic component) slips or falls off the substrate electrode even when pressure is applied during component mounting. It is said that the mounting yield improves because it does not tilt.

JP 2002-261407 A

  However, in the printed wiring board, the connection electrode (bump electrode) disposed on the metal conductive layer is prevented from slipping or slipping off and tilting due to the anchor effect due to the unevenness on the surface of the metal conductive layer. However, it does not have a structure that increases the bonding strength between them, and further increases the bonding strength between a plurality of electrodes. Therefore, if misalignment occurs at the time of joining or misalignment occurs between the electrodes due to poor positional accuracy between the electrodes (between the land and the bump electrode), it is sufficient between these electrodes. There is a possibility that the bonding strength cannot be obtained and contact failure (conductivity failure) may still occur. In addition, since the connection electrode (bump electrode) is made of metal, the connection electrode undergoes plastic deformation at the time of connection, and when the distance between the land and the bump electrode is not constant as described above, the distance change due to elastic deformation is absorbed. Since the capability is low, sufficient bonding strength between these electrodes cannot be obtained, and there is a possibility that contact failure (conductivity failure) may still occur.

  The present invention has been made in view of the above circumstances, and its object is to increase the bonding strength between the bump electrode and the substrate-side terminal to improve the reliability of the conductive connection state, and the mounting structure of the electronic component To provide a body.

  The electronic component mounting structure of the present invention is an electronic component mounting structure in which an electronic component having a bump electrode is mounted on a substrate having a terminal, and the bump electrode has an internal resin as a core. The bump electrode has a structure in which the surface is covered with a conductive film, and the bump electrode is elastically deformed to follow the shape of at least one corner of the terminal. The conductive film is in direct conductive contact with at least a part of the surface corresponding to the thickness direction of the terminal, and the bump electrode is elastically deformed between the substrate and the electronic component so that the terminal is electrically conductive. A holding means for holding the contacted state is provided.

According to the electronic component mounting structure, since the bump electrode has the internal resin as a core, it is easily pressed and elastically deformed (compressed) by being pressed against the terminal on the substrate. By joining to the terminal while being elastically deformed in this way, for example, a positional deviation occurs between the bump electrode and the terminal, and even if the bump electrode is joined on the corner of the terminal, the bump electrode is in the shape of the terminal. By following the above, the conductive film comes into direct conductive contact with at least a part of the upper surface of the terminal and at least a part of the surface corresponding to the thickness direction of the terminal. Therefore, since the conductive contact state is held by the holding means, a sufficient contact area is ensured between the conductive film of the bump electrode and the terminal, and a good conductive connection state is obtained.
Also, since the bump electrode generates an elastic restoring force (repulsive force) on the terminal of the substrate due to the elastic deformation of its internal resin, the bonding strength between the bump electrode and the terminal is higher, and the conductive connection state Reliability is improved. In particular, since the bump electrode is elastically deformed following the shape of at least one corner of the terminal, the elastic restoring force of the internal resin acts so as to sandwich the corner. The bonding strength between the terminals becomes higher.

In the electronic component mounting structure, it is preferable that the holding means is formed of a sealing resin that is filled and cured around a conductive contact portion between the bump electrode and the terminal.
In this way, a conductive contact state between the bump electrode and the terminal that are elastically deformed and the terminal is better secured, and a conductive connection state between the conductive film of the bump electrode and the terminal becomes better.

In the electronic component mounting structure, the electronic component is provided with a plurality of bump electrodes, the substrate is provided with a plurality of terminals, and the plurality of terminals are formed on the upper surface portion of the electronic component. The electronic component has at least two terminals having different distances from the surface on which the bump electrode is formed, and the bump electrode corresponds to the corresponding at least two terminals, and the bump electrode in the electronic component on the upper surface of these terminals. Corresponding to the distance to the forming surface, each may be elastically deformed with different degrees.
When a plurality of terminals are formed on a substrate and a plurality of bump electrodes are formed on an electronic component, the height (level) of the bonding surface of each terminal may vary due to, for example, distortion of the substrate. . Then, the plurality of terminals have terminals whose upper surface portions are different in distance from the bump electrode formation surface of the electronic component. Similarly, the height of the joint surface of the bump electrode may vary on the electronic component side.
And, when trying to connect a substrate having a height variation between terminals and an electronic component having a height variation between bump electrodes in the same way between a plurality of bump electrodes and terminals, these bump electrodes and terminals Since there is a variation in the distance between them before joining, it becomes difficult to connect all the bump electrodes and terminals with good strength.

  However, in the mounting structure according to the present invention, the bump electrode is elastically deformed to a different degree corresponding to the distance of the upper surface portion of the terminal to the bump electrode formation surface of the electronic component. The variation in the distance between the bump electrode and the terminal is absorbed by the elastic deformation of the bump electrode. Therefore, although the substrate and the electronic component have terminals and bump electrodes having variations in height (level), each of the bump electrodes and the terminals has a good bonding strength. can get. Therefore, according to this mounting structure, the reliability of the conductive connection state in each connection portion is improved, and the mounting strength of the electronic component on the board is also improved.

In the electronic component mounting structure, it is preferable that the bump electrode is in direct conductive contact with the entire upper surface of the terminal.
Since the conductive film of the bump electrode is in direct conductive contact with the entire upper surface of the terminal, the conductive film is in direct conductive contact with the entire upper surface of the terminal and at least a part of the surface corresponding to the thickness direction of the terminal. become. Therefore, a large contact area is ensured between the conductive film of the bump electrode and the terminal, a good conductive connection state is obtained, and the bonding strength between the bump electrode and the terminal is higher, and the reliability of the conductive connection state is improved. Will improve.

In the electronic component mounting structure, it is preferable that the bump electrode is in direct conductive contact with the entire surface corresponding to the thickness direction of the terminal.
Since the conductive film of the bump electrode is in direct conductive contact with the entire one surface corresponding to the thickness direction of the terminal, the conductive film has one surface corresponding to at least a part of the upper surface portion of the terminal and the thickness direction of the terminal. Direct conductive contact is made to the entire surface. Therefore, a large contact area is secured between the conductive film of the bump electrode and the terminal, and a good conductive connection state is obtained, and the bonding strength between the bump electrode and the terminal is further increased, and the reliability of the conductive connection state is improved. Will improve.

Further, in the electronic component mounting structure, the bump electrode is configured such that the conductive film is in direct conductive contact with at least a part of each surface of all surfaces corresponding to the thickness direction of the terminal. It is preferable.
Since the conductive film of the bump electrode is in direct conductive contact with all surfaces corresponding to the thickness direction of the terminal, the conductive film corresponds to at least a part of the upper surface portion of the terminal and the thickness direction of the terminal. All surfaces come into direct conductive contact. Therefore, a larger contact area is ensured between the conductive film of the bump electrode and the terminal, a good conductive connection state is obtained, and the bonding strength between the bump electrode and the terminal is higher, and the conductive connection state is reliable. Improves.

In the electronic component mounting structure, it is preferable that at least a part of the internal resin or the conductive film of the bump electrode is in contact with the substrate surface in the peripheral portion of the terminal in conductive contact.
Even if there is a variation in height between the bump electrode and the terminal, and the bump electrode and the terminal have a variation in the distance between them before joining, the bump electrode contacts the substrate surface around the terminal after joining. Therefore, there are continuously places in the internal resin of the bump electrode that have different compression ratios (elastic deformation ratios). Therefore, the bump electrode has a place having an optimum connection force (compression ratio) with respect to the terminal in the inside thereof, and therefore, the bonding (adhesion) reliability between the bump electrode and the terminal is improved.
In particular, when the internal resin is in contact with the substrate surface, current leakage (migration) is suppressed by the internal resin between adjacent terminals across the internal resin in contact with the substrate surface.

Further, in the electronic component mounting structure, at least a part of the inner resin or the conductive film of the bump electrode has depressed the substrate surface by pressing the substrate surface in the periphery of the terminal in conductive contact. In the state, it is preferable to contact the substrate surface.
Since the bump electrode is in contact with the substrate surface with the substrate surface in the periphery of the terminal being recessed, the bonding (adhesion) strength between the bump electrode and the terminal is further increased by the anchor effect, and therefore, For example, even if a peeling force is generated between the bump electrode and the terminal by a thermal cycle test, a good conductive connection state is secured against this.
Further, as described above, the bonding (adhesion) reliability between the bump electrode and the terminal is improved, and further, current leakage (migration) is suppressed between adjacent terminals.

Further, in the electronic component mounting structure, the internal resin is formed in a substantially bowl shape having a substantially semicircular shape, a substantially semielliptical shape, or a substantially trapezoidal cross section, and the conductive film includes the internal resin The resin may be provided in a strip shape on the upper surface portion along the cross-sectional direction of the resin.
In this way, by providing a plurality of conductive films at intervals on the upper surface of the internal resin, a plurality of bump electrodes can be formed, and manufacturing is facilitated.

In the electronic component mounting structure, the internal resin may be formed in a substantially hemispherical shape or a substantially truncated cone shape, and the conductive film may be provided so as to cover an upper surface of the internal resin.
In this way, since the bump electrode is curved in substantially the same way in all directions from the center, even if a positional deviation occurs with respect to the terminal, the bump electrode is in the same state with respect to the terminal. It follows the corner shape. Therefore, a stable conductive connection state is ensured between the terminals.

It is a schematic perspective view which shows typically the structure of the liquid crystal display device to which this invention was applied. (A) and (b) are the principal part enlarged views of the mounting structure which concerns on this invention. (A) and (b) are sectional side views which show schematic structure of a bump electrode. (A)-(d) is a figure for demonstrating the mounting structure of 1st Embodiment. (A) and (b) are the plane enlarged views for demonstrating the structure of a terminal. It is a figure for demonstrating the mounting structure of 2nd Embodiment. It is a figure for demonstrating the modification of the mounting structure of 2nd Embodiment. It is a figure for demonstrating the mounting structure of 3rd Embodiment. It is a figure for demonstrating the modification of the mounting structure of 3rd Embodiment. It is a figure for demonstrating the modification of the mounting structure of 3rd Embodiment. It is a perspective view which shows schematic structure of a bump electrode.

The electronic component mounting structure of the present invention will be described in detail below.
FIG. 1 is a schematic view showing a liquid crystal display device to which an electronic component mounting structure according to the present invention is applied. First, an application example of the electronic component mounting structure according to the present invention will be described with reference to FIG.
In FIG. 1, reference numeral 100 denotes a liquid crystal display device. The liquid crystal display device 100 includes a liquid crystal panel 110 and an electronic component (IC chip for liquid crystal drive) 121. Although not shown, the liquid crystal display device 100 is appropriately provided with incidental members such as a polarizing plate, a reflective sheet, and a backlight as necessary.

  The liquid crystal panel 110 includes substrates 111 and 112 made of glass or synthetic resin. The substrate 111 and the substrate 112 are arranged to face each other and are bonded to each other by a seal material (not shown). A liquid crystal (not shown) that is an electro-optical material is sealed between the substrate 111 and the substrate 112. An electrode 111a made of a transparent conductive material such as ITO (Indium Tin Oxide) is formed on the inner surface of the substrate 111, and an electrode 112a is formed on the inner surface of the substrate 112 so as to face the electrode 111a.

  The electrode 111a is connected to the wiring 111b integrally formed of the same material, and is drawn out on the inner surface of the substrate extension portion 111T provided on the substrate 111. The substrate overhanging portion 111T is a portion that protrudes outward from the outer shape of the substrate 112 at the end of the substrate 111. One end of the wiring 111b is a terminal 111bx. The electrode 112a is also connected to the wiring 112b integrally formed of the same material, and is conductively connected to the wiring 111c on the substrate 111 through a vertical conduction portion (not shown). The wiring 111c is also formed of ITO. The wiring 111c is drawn out on the substrate overhanging portion 111T, and one end thereof is a terminal 111cx. An input wiring 111d is formed in the vicinity of the edge of the substrate overhanging portion 111T, and one end thereof is a terminal 111dx. The terminal 111dx is disposed opposite to the terminals 111bx and 111cx. The other end of the input wiring 111d is an input terminal 111dy.

  An electronic component 121 according to the present invention is mounted on the substrate extension 111T via a sealing resin 122 made of a thermosetting resin. The electronic component 121 is, for example, a liquid crystal driving IC chip that drives the liquid crystal panel 110. A large number of bump electrodes (not shown) according to the present invention are formed on the lower surface of the electronic component 121, and these bump electrodes are conductively connected to the terminals 111bx, 111cx, and 111dx on the substrate extension portion 111T, respectively. Has been. Thereby, the mounting structure of the present invention in which the electronic component 121 is mounted on the substrate 111 is formed.

  In addition, a flexible wiring substrate 123 is mounted on the array region of the input terminals 111dy on the substrate extension 111T via an anisotropic conductive film 124. The input terminal 111 dy is conductively connected to wiring (not shown) corresponding to each of the input terminals 111 dy provided on the flexible wiring board 123. A control signal, a video signal, a power supply potential, and the like are supplied to the input terminal 111dy from the outside via the flexible wiring board 123. A control signal, a video signal, a power supply potential, and the like supplied to the input terminal 111dy are input to the electronic component 121, where a drive signal for driving the liquid crystal is generated and supplied to the liquid crystal panel 110. The flexible substrate is a flexible organic substrate such as polyimide or liquid crystal polymer, and a circuit pattern and a terminal are often formed of copper or aluminum on the substrate, but it is not necessarily limited thereto. It is even better if the surface of the terminal portion is gold-plated because the connection resistance is stabilized.

  According to the liquid crystal display device 100 configured as described above, when an appropriate voltage is applied between the electrode 111a and the electrode 112a via the electronic component 121, the both electrodes 111a and 112a are arranged to face each other. The light can be modulated independently for each pixel included in the portion, whereby a desired image can be formed in the display area of the liquid crystal panel 110.

Next, an embodiment of the electronic component mounting structure of the present invention applied to the liquid crystal display device 100 will be described.
FIG. 2A is an enlarged perspective view of a main part showing an enlarged mounting structure of the electronic component 121 in the liquid crystal display device 100, and FIG. 2B is an AA line in FIG. It is arrow sectional drawing. 2A and 2B, reference numeral 11P represents a wiring pattern provided on the substrate 111, that is, one of the wirings 111b, 111c, and 111d, and reference numeral 11 represents a terminal provided on these wirings. That is, it represents one of the terminals 111bx, 111cx, and 111dx. In the present embodiment, the terminal 11 has a relatively large film thickness and is therefore formed high, and its cross section is substantially trapezoidal. Reference numeral 12 denotes a bump electrode provided on the electronic component 121. Although not shown in FIG. 2A, at least a conductive contact portion between the bump electrode 12 and the terminal 11 is provided between the substrate 111 and the electronic component 121 as shown in FIG. Covering the periphery, the sealing resin 122 is filled and arranged and cured. The sealing resin 122 is preferably an epoxy resin, an acrylic resin, or a phenol resin, but may be a resin, and the type of resin is not limited thereto.

  In the present embodiment, the bump electrode 12 has a substantially bowl-shaped internal resin 13 provided on the electronic component 121 as a core, as shown in the side sectional views of FIGS. 2 (a), 3 (a), and 3 (b). The surface is covered with the conductive film 14. As shown in FIGS. 3A and 3B, the conductive film 14 is connected and conducted to the electrode 16 exposed in the opening of the insulating film 15 on the surface of the electronic component 121, and is drawn around the internal resin 13. It is a thing. The conductive film 14 covering the surface of the internal resin 13 with such a configuration is electrically connected to the electrode 16, and thus substantially functions as an electrode of the electronic component 121. In the present embodiment, as shown in FIG. 2A, a plurality of strip-like conductive films 14 are provided on the surface of the internal resin 13, and these conductive films 14 are each independently the electrode 16 of the electronic component 121. Is connected to or conductive. Therefore, each of these conductive films 14 functions independently as the bump electrode 12 in the present invention together with the internal resin 13 located inside thereof.

  Here, the substantially saddle shape refers to a columnar shape in which the inner surface (bottom surface) in contact with the electronic component 121 is a flat surface and the outer surface side not in contact with the surface is a curved surface. Specifically, the cross section is substantially semicircular as shown in FIG. 3 (a), is substantially semi-elliptical although not shown, or cross section as shown in FIG. 3 (b). Those having a substantially trapezoidal shape are preferably used. In the case of the substantially trapezoidal cross section shown in FIG. 3 (b), at least the shoulder between the upper surface and the side surface is curved in this cross sectional shape. The outer surface that does not contact the component 121 is a curved surface.

  The internal resin 13 is made of a photosensitive insulating resin or a thermosetting insulating resin. Specifically, the internal resin 13 is formed of a polyimide resin, an acrylic resin, a phenol resin, a silicone resin, a silicone-modified polyimide resin, an epoxy resin, or the like. It is. The internal resin 13 made of such a resin is formed in a substantially bowl shape as described above by a known lithographic technique or etching technique. The resin material (hardness) and the shape (height and width) in details about the bowl shape are appropriately selected and designed according to the shape and size of the terminal 11 as will be described later.

  The conductive film 14 is made of a metal or alloy such as Au, TiW, Cu, Cr, Ni, Ti, W, NiV, Al, Pd, or lead-free solder, and even if it is a single layer of these metals (alloys). A plurality of types may be laminated. Further, such a conductive film 14 may be formed by a known film formation method such as a sputtering method and then patterned into a band shape, or may be formed selectively by electroless plating. Good. Alternatively, a base film may be formed by sputtering or electroless plating, and then an upper layer film may be formed on the base film by electrolytic plating, and the conductive film 14 may be formed by a laminated film including the base film and the upper layer film. Good. Note that the type, layer structure, film thickness, width, and the like of the metal (alloy) are appropriately selected and designed according to the shape and size of the terminal 11 as in the case of the internal resin 13. However, as will be described later, the conductive film 14 is elastically deformed following the shape of the corner of the terminal 11, and therefore, it is preferable to use gold (Au) having particularly excellent spreadability. Further, when the conductive film 14 is formed of a laminated film, it is preferable to use gold for the outermost layer. Furthermore, the width of the conductive film 14 is preferably formed sufficiently wider than the width of the terminal 11 to be joined.

  FIG. 4A is a view showing a state before the electronic component 121 is mounted on the substrate 111, and is an enlarged cross-sectional view of a main part corresponding to the main part of FIG. The substrate 111 and the electronic component 121 are positioned so that the terminals 11 and the bump electrodes 12 face each other, and are pressed in such a direction that they are joined to each other. As shown, the conductive film 14 of the bump electrode 12 is joined to the terminal 11 to make conductive contact. Then, in the state where the conductive film 14 and the terminal 11 are in conductive contact, that is, in a state where the conductive film 14 and the terminal 11 are pressurized with a predetermined pressure, the sealing resin 122 (FIG. 2 ( b) is filled between the substrate 111 and the electronic component 121 and cured. Thereby, the mounting structure 10 which becomes 1st Embodiment of this invention is obtained. Note that the sealing resin 122 as the holding unit is provided in an uncured state (or a semi-cured state) between the substrate 111 and the electronic component 121 in advance, and the conductive film 14 and the terminal 11 are brought into conductive contact. After that, the conductive film 14 and the terminal 11 may be conductively contacted, and then the uncured sealing resin 122 is filled between the substrate 111 and the electronic component 121 and then cured. Good.

  In the mounting structure 10 according to the first embodiment of the present invention formed as described above, the electronic component 121 is relatively pressed toward the substrate 111, whereby the bump electrode 12 is brought into contact with the terminal 11. Further, by being pressurized in that state, the bump electrode 12 is elastically deformed (compressed) into a desired form. That is, the bump resin 12 is sufficiently soft as the internal resin 13 serving as the core thereof is softer than the terminal 11 made of metal, so that it is elastically deformed and compressed by being pressurized. At that time, since the internal resin 13 and the conductive film 14 formed thereon are formed wider than the terminal 11, the internal resin 13 protrudes to the outside (side surface side) of the terminal 11 and follows the shape of all corners of the terminal 11. It becomes a shape.

  In other words, the bump electrode 12 follows the shape of all the corners of the terminal 11 mainly by elastic deformation of the internal resin, whereby the conductive film 14 extends in the thickness direction of the terminal 11 and at least a part of the upper surface of the terminal 11. All the corresponding surfaces come into direct conductive contact. Here, the surface corresponding to the thickness direction of the terminal 11 refers to the side surface 11b located on both sides of the upper surface 11a of the terminal 11 in FIG. 4 (d), which is an enlarged view of FIG. 4 (b). The corner portion refers to a corner portion 11c formed by the intersection of the upper surface 11a and the side surface 11b. In the present embodiment, the cross-sectional shape of the terminal 11 is substantially trapezoidal, but it may be rectangular. Further, the thickness (height) is not limited to a thick (high) material but may be a relatively thin (low) material.

  Further, as shown in FIG. 5A, which is an enlarged plan view, the terminal 11 of the substrate 111 may be an end portion of the wiring pattern 11P. In that case, a hatched line in FIG. As shown by, a region of a predetermined length from the edge of the wiring pattern 11P becomes the terminal 11 in the present invention. Further, as shown in FIG. 5B, which is an enlarged plan view, a land formed wider at the end of the wiring pattern 11P than the wiring pattern 11P, that is, a region indicated by hatching in FIG. 5B. The terminal 11 in the present invention may be used. In the mounting structure 10 shown in FIG. 4D, the conductive film 14 of the bump electrode 12 has the upper surface of the terminal 11, that is, the entire surface (the whole) of the region shown by hatching in FIGS. 5A and 5B. In direct conductive contact.

  Further, the bump electrode 12 follows the shape of all the corners of the terminal 11 by elastic deformation, so that the conductive film 14 is in direct conductive contact with a part of the side surface 11b of the terminal 11 as described above. In the case where the terminal 11 has the shape shown in FIG. 5A, the conductive film 14 is also in direct conductive contact with a part of the outer surface 11d of the terminal 11 serving as the edge of the wiring pattern 11P. In the case where the terminal 11 has the shape shown in FIG. 5B, the conductive film 14 is in direct conductive contact with a part of the inner side surface 11e opposite to the outer side surface 11d of the terminal 11 as well. Yes.

  Here, in FIG. 4D, the conductive film 14 is shown as being in contact with substantially the upper half of the side surface 11b, but may be in contact with only the upper end portion of the side surface 11b. Moreover, you may touch only the upper end part of above-described outer side surface 11d and inner side surface 11e. That is, in the mounting structure according to the present invention, the conductive film 14 may be in contact with only part of the side surface 11b, the outer surface 11d, and the inner surface 11e of the terminal 11 by following the shape of the corner of the terminal 11. In other words, since the bump electrode 12 follows the corner shape of the terminal 11 by elastic deformation, the conductive film 14 comes into contact with at least a part of the side surface 11b, the outer surface 11d, and the inner surface 11e of the terminal 11. is there.

  In such a mounting structure 10, the bump electrode 12 follows the shape of the terminal 11, whereby the conductive film 14 is formed on the entire upper surface 11 a, the side surface 11 b, the outer surface 11 d, and a part of the inner surface 11 e of the terminal 11. Are in direct conductive contact, and this conductive contact state is held by the sealing resin 122. Therefore, a sufficient contact area is ensured between the conductive film 14 and the terminal 11, and a favorable conductive connection state is established between the conductive film 14 and the terminal 11. Further, since the bump electrode 12 generates an elastic restoring force (repulsive force) on the terminal 11 due to the elastic deformation of the internal resin 13, the bonding strength between the bump electrode 13 and the terminal becomes higher, and the conductive connection State reliability is improved. In particular, since the bump electrode 12 is elastically deformed following the shape of the plurality of corner portions 11c of the terminal 11, the restoring force of the internal resin 13 acts to sandwich the corner portions 11c. Thus, the bonding strength between the bump electrode 12 and the terminal 11 is higher. Therefore, the mounting structure 10 of this embodiment is extremely excellent in that the bonding strength between the bump electrode 12 and the terminal 11 on the substrate side is sufficiently increased and the reliability of the conductive connection state is improved.

FIG. 6 is a view showing a second embodiment of the electronic component mounting structure according to the present invention. The second embodiment is different from the first embodiment shown in FIG. 4D in that the conductive film 14 of the bump electrode 12 does not follow the corners 11c on both sides of the terminal 11 and the corners 11c on one side. It is a point that only imitates.
In recent years, electronic component mounting structures have been increasingly miniaturized and highly integrated, and the pitch and wiring width between wirings have been further narrowed. Therefore, conventionally, if the bump electrode or the terminal is displaced during manufacturing, or if misalignment occurs between the substrate and the electronic component, sufficient bonding strength cannot be obtained between the bump electrode and the terminal. There was a risk of causing poor contact (conductive failure).
Therefore, the mounting structure of the second embodiment has a structure in which poor contact is prevented even when such misalignment or misalignment occurs.

  That is, in the mounting structure 20 shown in FIG. 6, the bump electrode 12 is displaced in the width direction of the terminal 11, that is, in the width direction of the wiring pattern 11P in FIGS. Yes. Therefore, the conductive film 14 is not in direct contact with the entire upper surface 11a of the terminal 11 but in contact with only the side surface 11b. However, even if such a displacement occurs, the mounting structure 20 of the present embodiment follows the corner 11c on one side of the terminal 11 as described above, and thus a part of the upper surface 11a of the terminal 11 is used. The conductive film 14 is in direct conductive contact with a part of at least one side surface 11b, and this conductive contact state is held by a sealing resin 122 (not shown).

Therefore, a sufficient contact area is ensured between the conductive film 14 and the terminal 11, and a favorable conductive connection state is established between the conductive film 14 and the terminal 11. Further, since the bump electrode 12 generates an elastic restoring force (repulsive force) on the terminal 11 due to the elastic deformation of the internal resin 13, the bonding strength between the bump electrode 13 and the terminal becomes higher, and the conductive connection State reliability is improved. Moreover, since the restoring force of the internal resin 13 acts so as to sandwich the one corner 11c, the bonding strength between the bump electrode 12 and the terminal 11 is higher as described above.
Therefore, even in the mounting structure 20 formed by such positional deviation and misalignment, the bonding strength between the bump electrode 12 and the terminal 11 on the substrate side is sufficiently increased, and the conductive connection state is obtained. Reliability is improved and contact failure is prevented and excellent.

The characteristics of the internal resin 13, particularly its hardness and elastic deformability (compressibility), can be changed as appropriate depending on the type and composition of the resin, processing conditions, and the like. Further, the degree of elastic deformation of the bump electrode 12 at the time of mounting can be appropriately changed depending on the pressure condition between the substrate 111 and the electronic component 121. Therefore, in the second embodiment, as a modified example, the degree of elastic deformation (compression) of the bump electrode 12 is increased, and the conductive film 14 is brought into contact with the entire side surface 11b as shown in FIG. You may make it make it.
In this way, a larger contact area can be ensured between the conductive film 14 of the bump electrode 12 and the terminal 11, and thereby a better conductive connection state can be obtained. In addition, the bonding strength between the bump electrode 12 and the terminal 11 can be increased, and the reliability of the conductive connection state can be improved.

  FIG. 8 is a view showing a third embodiment of the electronic component mounting structure according to the present invention. The third embodiment is different from the first embodiment shown in FIG. 4D in that a plurality of bump electrodes 12 are provided on the electronic component 121 and a plurality of terminals 11 are provided on the substrate 111. That is, the bump electrode 12 and the terminal 11 are joined (connected), and the height level of the terminal 11 is particularly uneven.

When a plurality of terminals 11 are formed on the substrate 111, the height (level) of the bonding surface (upper surface) of each terminal 11 with respect to the bump electrode 12 may vary due to, for example, distortion of the substrate 111. . Then, the upper surfaces (bonding surfaces) of the plurality of terminals 11 have different distances with respect to the formation surface of the bump electrode 12 in the electronic component 121. Similarly, on the electronic component 121 side, the height of the bonding surface of the bump electrode 12 may vary.
When the substrate 111 having the height variation between the terminals 11 and the electronic component 121 having the height variation similarly between the bump electrodes 12 are connected between the plurality of bump electrodes 12 and the terminals 11, Since the distance between the bump electrode 12 and the terminal 11 varies before bonding, it is difficult to connect all the bump electrodes 12 and the terminals 11 with good strength.

  However, in the mounting structure 30 of the present embodiment shown in FIG. 8, the height of the terminal 11A and the terminal 11B differs depending on, for example, the distortion of the substrate 111. Therefore, the bump on the electronic component 121 from the upper surface 11a of the terminal 11A. Even if the distance L1 to the formation surface of the electrode 12 is different from the distance L2 from the upper surface 11a of the terminal 11B to the formation surface of the bump electrode 12, the distance between the terminal 11A and the bump electrode 12 and the distance between the terminal 11B and the bump electrode 12 are different. However, both are well joined (connected).

  That is, in this mounting structure 30, each bump electrode 12 having the internal resin 13 is elastically deformed to a different degree corresponding to the distance L1 or distance L2 of the terminal 11 to be joined. The difference from L2, that is, the variation in the distance between the bump electrode 12 and the terminal 11, is absorbed by the elastic deformation of the bump electrode 12. Therefore, even if the substrate 111 and the electronic component 121 have a variation in height (level) on the terminal 11 or a variation in height level on the bump electrode 12 side, these variations are not affected by the bump electrode 12. Absorbing by elastic deformation, it is possible to obtain good bonding strength between each of the plurality of bump electrodes 12 and the terminals 11.

  In addition, when joining (connection) is made between the plurality of terminals 11 and the bump electrodes 12 in this way, it is preferable to further increase the degree of elastic deformation (compression) of the bump electrodes 12. That is, by increasing the elastic deformability (compressibility) of the internal resin 13 and / or increasing the pressure between the substrate 111 and the electronic component 121 during mounting, the mounting structure 40 shown in FIG. As described above, it is preferable that a part of the bump electrode 12 is brought into contact with the surface of the substrate 111 around the terminal 11 in conductive contact. Here, the bump electrode 12 is not only the conductive film 14 and the internal resin 13 covered by the conductive film 14 but also the internal resin 13 located in the vicinity of the conductive film 14, that is, the internal resin exposed without being covered by the conductive film 14. 13 is also included.

In such a mounting structure 40, the terminal 11 and the bump electrode 12 have variations in height as described above. Therefore, there is a variation in the distance between the terminal 11 and the bump electrode 12 before bonding. However, since the bump electrode 12 is in contact with the surface of the substrate 111 in the peripheral portion of the terminal 11 after bonding, the variation is surely absorbed by the elastic deformation of the bump electrode 12, and the bump electrodes 12 Good bonding strength can be obtained between the terminal 11 and each terminal. In addition, since the places where the compressibility (elastic deformation rate) differs continuously exist in the internal resin 13 of the bump electrode 12, the bump electrode 12 has an optimum connection force with respect to the terminal 11 therein. There will be places with (compression ratio). Therefore, the bonding (adhesion) reliability between the bump electrode 12 and the terminal 11 is improved.
Further, since the internal resin 13 located in the vicinity of the conductive film 14 is in contact with the surface of the substrate 111, between the adjacent terminals 11A and 11B across the internal resin 13 in contact with the surface of the substrate 111. Current leakage (migration) is suppressed by the insulating internal resin 13.

  Further, in the case where bonding (connection) is made between the plurality of terminals 11 and the bump electrodes 12, the elastic deformation property (compressibility) of the internal resin 13 itself and the addition between the substrate 111 and the electronic component 121 during mounting. By adjusting the pressure, as in the mounting structure 50 shown in FIG. 10, a part of the bump electrode 12 presses the surface of the substrate 111 in the peripheral portion of the terminal 11 that is in conductive contact with the substrate 111. It is preferable that the surface of the substrate 111 is in contact with the surface of the substrate 111 being recessed.

Even in such a mounting structure 50, when the terminal 11 or the bump electrode 12 has a height variation, the bump electrode 12 abuts against the surface of the substrate 111 in the periphery of the terminal 11 to press it. Therefore, the variation is surely absorbed by the elastic deformation of the bump electrode 12, and good bonding strength is obtained between the plurality of bump electrodes 12 and the terminals 11.
Further, since the bump electrode 12 is in contact with the surface of the substrate 111 in the peripheral portion of the terminal 11 being recessed, the bonding (adhesion) strength between the bump electrode 12 and the terminal 11 is further increased by the anchor effect. Get higher. Therefore, for example, even if a peeling force is generated between the bump electrode 12 and the terminal 11 by a thermal cycle test, a good conductive connection state is ensured against this.
Further, since the internal resin 13 located in the vicinity of the conductive film 14 is in contact with the surface of the substrate 111, between the adjacent terminals 11, 11 across the internal resin 13 in contact with the surface of the substrate 111. Current leakage (migration) is suppressed by the insulating internal resin 13.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. For example, the bump electrode has a structure in which the internal resin is not formed in a substantially bowl shape as shown in FIGS. 2 (a), 3 (a) and 3 (b), but as shown in FIG. The resin 17 may be formed in a substantially hemispherical shape, and the conductive film 18 may be provided so as to cover the entire top surface of the internal resin 17 and to be electrically connected to the electrode 16 of the electronic component.
If such a structure is adopted, since this bump electrode is curved with substantially the same curvature in all directions from the center of the internal resin 17, no matter which direction misalignment occurs with the terminal 11, In the same state as the terminal 11, the corner shape is followed. Therefore, a stable conductive connection state with the terminal 11 can be ensured. The internal resin 17 may have a substantially truncated cone shape instead of a substantially hemispherical shape. The conductive film 18 may be provided so as to cover only a part of the inner resin 17 having a substantially hemispherical shape or a substantially truncated cone shape without covering the entire upper surface.

  In the above embodiment, the sealing resin 122 is used as the holding means in the present invention. However, the holding means of the present invention is configured by various mechanical pressure bonding means such as screws, clips, or coupling by fitting. Also good. Further, even when an adhesive (resin) is used, it is selectively disposed, for example, only between the outer peripheral portion of the electronic component and the substrate without being disposed around the conductive contact portion between the bump electrode 12 and the terminal 11. You may make it distribute to.

In addition to the substrate made of glass or synthetic resin, various substrates such as a rigid substrate, a silicon substrate, and a thin ceramic substrate can be used as the substrate 111. In addition to the IC chip for driving the liquid crystal, the electronic component has various ICs and connection electrodes (bump electrodes) as described above, such as passive components such as diodes, transistors, light emitting diodes, laser diodes, oscillators and capacitors. Any electronic component can be used.
In addition, the device to which the electronic component mounting structure of the present invention is applied is not limited to the above-described liquid crystal display device, but also an organic electroluminescence device (organic EL device), a plasma display device, an electrophoretic display device, and an electron emission device. The present invention is applicable to various electro-optical devices and various electronic modules such as devices using elements (Field Emission Display, Surface-Conduction Electron-Emitter Display, etc.).

  10, 20, 30, 40, 50... Mounting structure (electronic component mounting structure), 11... Terminal, 11a... Upper surface, 11b .. side surface, 11c. ... wiring pattern, 12 ... bump electrode, 13, 17 ... internal resin, 14, 18 ... conductive film, 100 ... liquid crystal display device, 110 ... liquid crystal panel, 111 ... substrate, 111a, 112a ... electrode, 111b, 112b, 111c ... Wiring, 111d ... input wiring, 111bx, 111cx, 111dx ... terminal, 121 ... electronic component (IC chip), 122 ... sealing resin (holding means).

Claims (10)

An electronic component mounting structure in which an electronic component having a bump electrode is mounted on a substrate having terminals,
The bump electrode has a structure in which an inner resin is used as a core and the surface is covered with a conductive film, and the bump electrode is elastically deformed to follow the shape of at least one corner of the terminal. The conductive film is in direct conductive contact with at least part of the upper surface of the terminal and at least part of the surface corresponding to the thickness direction of the terminal,
A mounting structure for an electronic component, wherein the substrate and the electronic component are provided with holding means for holding a state in which the bump electrode is elastically deformed and is in conductive contact with the terminal.   2. The electronic component mounting structure according to claim 1, wherein the holding means is made of a sealing resin which is filled and cured around a conductive contact portion between the bump electrode and the terminal. . The electronic component is provided with a plurality of bump electrodes, and the substrate is provided with a plurality of terminals.
The plurality of terminals have at least two terminals whose upper surface portions are different in distance from the formation surface of the bump electrode in the electronic component,
The bump electrodes are elastically deformed with different degrees with respect to the corresponding at least two terminals in accordance with the distances of the upper surface portions of the terminals from the bump electrode forming surface of the electronic component. The electronic component mounting structure according to claim 1, wherein the electronic component mounting structure is a structure.   4. The electronic component mounting structure according to claim 1, wherein the conductive film is in direct conductive contact with the entire upper surface of the terminal.   5. The electronic component according to claim 1, wherein the conductive film is in direct conductive contact with the entire surface of the bump electrode corresponding to the thickness direction of the terminal. 6. Implementation structure.   6. The bump electrode according to claim 1, wherein the conductive film is in direct conductive contact with at least a part of each surface of all the surfaces corresponding to the thickness direction of the terminal. The electronic component mounting structure according to any one of the preceding claims.   7. The bump electrode according to claim 1, wherein at least a part of the inner resin or the conductive film is in contact with a substrate surface in a peripheral portion of a terminal in conductive contact. Electronic component mounting structure.   The bump electrode has at least a part of the inner resin or conductive film in contact with the substrate surface in a state where the substrate surface in the peripheral portion of the terminal in conductive contact is pressed and the substrate surface is recessed. The electronic component mounting structure according to claim 7.   The internal resin is formed in a substantially bowl shape having a substantially semicircular shape, a substantially semi-elliptical shape, or a substantially trapezoidal cross section, and the conductive film has an upper surface portion along the cross sectional direction of the internal resin. The electronic component mounting structure according to claim 1, wherein the electronic component mounting structure is provided in a band shape.   The electron according to any one of claims 1 to 8, wherein the inner resin is formed in a substantially hemispherical shape or a substantially truncated cone shape, and the conductive film is provided to cover an upper surface of the inner resin. Component mounting structure.

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