JP2009099765A - Electronic component mounting structure - Google Patents

Abstract

Provided is an electronic component mounting structure in which a plurality of contact points formed by a plurality of bump electrodes and a plurality of terminals are all in an excellent conductive connection state even when the bump electrodes have a height variation.
An electronic component mounting structure is formed by mounting an electronic component having a bump electrode on a substrate having a terminal. A plurality of bump electrodes 12 and terminals 11 are provided, and the bump electrodes 12 and the terminals 11 are joined to each other corresponding to each other. The plurality of bump electrodes 12 have a structure in which the inner resin 13 is used as a core and the surface thereof is covered with a conductive film 14, and at least two bump electrodes 12 a and 12 b having different joint heights to be joined to the terminals 11. including. The plurality of bump electrodes 12 are bonded to the terminals 11 in a state in which the internal resin 13 is elastically deformed corresponding to the height of each bonding portion to absorb variations in the height of the bonding portions. Yes.
[Selection] Figure 2

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 electronic components are 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, for example, when the bump electrode forming surface of the electronic component is uneven or warped, or the bump electrode has a height variation, the distance between the bump electrode and the land is not constant. There was a risk that sufficient bonding strength could not be obtained, and contact failure (conductivity failure) was caused. Conventionally, when a plurality of bump electrodes are formed on an electronic component, a height variation of about 0.5 μm is formed between the bump electrodes.

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. That is, 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 becomes non-constant as described above, the distance change due to elastic deformation occurs. Since the absorption capacity is low, sufficient bonding strength between these electrodes cannot be obtained, and contact failure (conductivity failure) may still occur.
Therefore, especially when the bump electrode has a height variation, the distance between the bump electrode and the land is not constant, and sufficient bonding strength cannot be obtained between the bump electrode and the land, resulting in poor contact (conductivity). There was a risk of causing a failure.

  The present invention has been made in view of the above circumstances, and the object of the present invention is to provide a plurality of contact points formed by the plurality of bump electrodes and the plurality of substrate-side terminals even when the bump electrodes have variations in height. An object of the present invention is to provide an electronic component mounting structure that is in a good conductive connection state.

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,
A plurality of the bump electrodes and the terminals are provided, and the bump electrodes and the terminals are joined together corresponding to each other.
The plurality of bump electrodes include a structure in which an inner resin is used as a core and the surface thereof is covered with a conductive film, and includes at least two bump electrodes having different joint heights to be joined to the terminals,
The plurality of bump electrodes are bonded to the terminals in a state in which variations in the height of the bonding portions are absorbed by elastic deformation of the internal resins corresponding to the heights of the bonding portions. It is characterized by being.

  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. Then, 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, so that the bonding strength between the bump electrode and the terminal becomes higher, and the reliability of the conductive connection state Will improve.

In addition, when multiple bump electrodes are formed on an electronic component, the bump electrode forming surface of the electronic component has irregularities or warpage, or the bump electrode itself has manufacturing variations. There may be variations in the height (level) of the joints to be joined. As a result, the distances between the joints of the bump electrodes having variations in height are different from the terminals.
Then, when an electronic component having a variation in height between the bump electrodes and the substrate having the terminals are connected to each other between the plurality of bump electrodes and the terminals, the bump electrodes and the terminals are connected to each other before joining. Since there is variation in the distance between them, it becomes difficult to connect all the bump electrodes and terminals with good strength.

However, according to the mounting structure of the present invention, the bump electrode is elastically deformed at different degrees corresponding to the height of each joint, that is, corresponding to the distance between the joint and the terminal. Therefore, the variation in the distance between the bump electrode and the terminal is absorbed by the elastic deformation of the bump electrode. Therefore, the bump electrode is bonded to the terminal in a state where the variation in the height of the bonding portion is absorbed. As a result, the bump electrode has a height (level) variation in the bump electrode. Regardless, the bump electrodes and the terminals are in a good conductive connection state. Therefore, according to this mounting structure, the reliability of the conductive connection state at each contact point (connection portion) is improved, and the mounting strength of the electronic component on the board is also improved.
Furthermore, in the past, electronic components were designed so that the bump electrode was formed with a flat surface with no steps, etc., so that the bump electrode did not vary in height. Then, since the variation in the height of the bump electrode is absorbed as described above, there is no problem even if there is a step on the bump electrode formation surface, and thus the degree of freedom in designing the electronic component is increased.

Further, in the electronic component mounting structure, the substrate and the electronic component are provided with holding means for holding the state in which the bump electrodes are elastically deformed and are in conductive contact with the terminals. preferable. In this case, it is preferable that the holding means is made of a sealing resin that is filled and cured around a conductive contact portion between the bump electrode and the terminal.
By providing the holding means, the conductive contact state between the bump electrode and the terminal that are elastically deformed and the terminal is better secured, and the conductive connection state between the conductive film of the bump electrode and the terminal is better. become. Further, if the holding means is made of a sealing resin, the conductive connection state between the conductive film and the terminal can be held well over a long period of time.

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, the bump electrode is curved in substantially the same direction from the center in all directions, so that, for example, in any direction with respect to the terminal, the position is almost the same with respect to the terminal. Come to join. Therefore, a stable conductive connection state is ensured between the terminals.

Further, in the electronic component mounting structure, the internal resin is formed in a substantially bowl shape having a substantially semicircular shape, a semi-elliptical shape, or a substantially trapezoidal cross section, and the conductive film is formed of the internal resin. It may be provided in a strip shape on the upper surface portion along the transverse cross-sectional direction.
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.

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, a first embodiment of the electronic component mounting structure of the present invention applied to the liquid crystal display device 100 will be described.
FIG. 2 is an enlarged cross-sectional view of a main part showing an enlarged mounting structure of the electronic component 121 in the liquid crystal display device 100. In FIG. 2, reference numeral 11 denotes a terminal provided on any of the wirings 111b, 111c, and 111d provided on the substrate 111, that is, any one of the terminals 111bx, 111cx, and 111dx. Reference numeral 12 denotes a bump electrode provided on the electronic component 121. Between the substrate 111 and the electronic component 121, a sealing resin 122 is filled and disposed so as to cover at least the periphery of the conductive contact portion between the bump electrode 12 and the terminal 11, and is cured. The sealing resin 122 is preferably an epoxy resin, an acrylic resin, or a phenol resin, but may be any resin and is not particularly limited.

  Further, in the present embodiment, the terminal 11 is formed by the additive method (plating growth method), so that the film thickness is relatively thick and therefore high, and the cross section thereof is substantially trapezoidal. It shall be. However, as the terminal 11, a thin film formed by sputtering as shown in FIG. 3B, even if the cross section formed by etching as shown in FIG. 3A is rectangular. Further, it may be a substantially bowl-shaped one formed by a printing method as shown in FIG.

In the present invention, as shown in FIG. 2, there are a plurality of bump electrodes 12, and at least two of these bump electrodes 12 are formed with different heights of joint portions to be joined to the terminals 11. Yes. That is, the plurality of bump electrodes 12 in the present invention include at least two bump electrodes 12a and 12b having different heights. Here, the height difference (height variation) of the bumps 12 is such that the bump electrode forming surface of the electronic component 121 has unevenness or warpage, that is, the case caused by the electronic component 121 and the bump electrode 12. It may be caused by manufacturing variations of itself. In the present invention, the variation in the height of the bump electrode 12 includes any case or both cases. In the present embodiment shown in FIG. 2, it is assumed that there is a height variation between the bump electrodes 12a and 12b due to the manufacturing variation of the bump electrode 12 itself.
The bump electrodes 12a and 12b having different heights are bonded to the terminals 11 in a state where the height variations (differences) of the bonded portions are absorbed by themselves.

  In this embodiment, the bump electrode 12 (12a, 12b) has a substantially hemispherical internal resin 13 provided on the electronic component 121 as a core, as shown in FIGS. It has a structure covered with a conductive film 14. As shown in FIGS. 5A and 5B, the substantially frustoconical internal resin 13 provided on the electronic component 121 is used as a core, and the surface thereof is covered with a conductive film 14. It may be.

  As shown in FIG. 4B or FIG. 5B, the conductive film 14 is connected / conductive to the electrode 16 exposed in the opening of the insulating film 15 on the surface of the electronic component 121, and on the internal resin 13. It has been routed. 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. The conductive film 14 may be provided so as to cover only the portion including the topmost portion without covering the entire upper surface of the inner resin 13 having a substantially hemispherical shape or a substantially truncated cone shape.

  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 into a substantially hemispherical shape or a substantially truncated cone shape by a known lithographic technique, etching technique, or reflow technique. At this time, there is a slight variation in the size and shape of the mask due to misalignment of the mask and the difference in the degree of reflow. That is, the height from the bottom to the top of the substantially hemispherical or substantially truncated cone shape varies. The details (height and width) of the resin material (hardness) and shape are appropriately selected and designed according to the shape and size of the terminal 11.

  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). In addition, 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 strip shape or a strip shape, or may be selectively formed by electroless plating. There may be. 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, since the conductive film 14 is elastically deformed following the shape of the terminal 11, 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.

  Thus, the bump electrode 12 is formed by providing the conductive film 14 so as to cover the internal resin 13. Then, between the plurality of internal resins 13, as described above, there is a variation in the height from the bottom portion to the topmost portion. Therefore, even between the plurality of obtained bump electrodes 12 (12 a, 12 b), between the internal resins 13. Due to the height variation, the heights are different from each other. And since the part including the top part of the bump electrode 12 becomes a joint part with the terminal 11, the bump electrode 12 (12 a, 12 b) is joined to the terminal 11 due to the height variation between the internal resins 13. Therefore, the heights of the joining portions are different, that is, the heights of the joining portions vary.

  FIG. 6A is a diagram showing a state before the electronic component 121 is mounted on the substrate 111, and is a cross-sectional view of the main part corresponding to FIG. The electronic component 121 and the substrate 111 are positioned so that the bump electrodes 12a and 12b and the terminals 11 and 11 face each other. At this time, since the bump electrodes 12a and 12b have a height variation, the distances L1 and L2 between the respective joint portions are different between the bump electrodes 12a and 12b and the terminal 11, that is, the variation is different. Therefore, it is difficult to connect all the bump electrodes 12 and the terminals 11 with good strength.

  Thus, in the present invention, under such a state, the electronic components 121 and the substrate 111 are pressurized in the direction in which they are joined to each other, thereby causing the bump electrodes 12a and 12b to be pressed as shown in FIG. The conductive films 14 are bonded to the corresponding terminals 11 and are in conductive contact. Then, since the internal resin 13 is easily elastically deformed (compressed) according to the applied pressure, each of the bump electrodes 12a and 12b is elastically deformed (compressed) by contacting the terminal 11 to be joined. That is, the internal resin 13 is elastically deformed at different degrees corresponding to the distance between the upper surface (joint part) of the terminal 11 and the joint part of the bump electrode 12a (12b), so that each conductive film 14 is also They are elastically deformed at different degrees and are joined to the terminals 11 in this state.

  Thereby, there is a height variation between the bump electrodes 12a and 12b, and even if the distance between the bump electrodes 12a and 12b and the terminal 11 varies, the bump electrodes 12a and 12b correspond to the respective distances. The variation is absorbed by elastic deformation. Therefore, the substrate 111 and the electronic component 121 have a good conductive connection state between the bump electrodes 12a and 12b and the terminal 11 even though the bump electrodes 12a and 12b have height (level) variations. Become.

  The sealing resin 122 (see FIG. 2) as the holding means in the present invention in such a state that the conductive film 14 and the terminal 11 are in conductive contact, that is, in a state of being pressurized with a predetermined pressure. ) Is filled between the substrate 111 and the electronic component 121 and cured. As a result, the mounting structure 10 according to the first embodiment of the present invention shown in FIG. 2 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 this 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 this time, since the internal resin 13 and the conductive film 14 formed thereon are formed wider than the terminal 11, it protrudes to the outside (side surface side) of the terminal 11 and covers the entire upper surface of the terminal 11. Get in touch.

Therefore, according to the mounting structure 10, the bump electrodes 12 a and 12 b generate elastic restoring force (repulsive force) with respect to the terminal 11 due to elastic deformation of the internal resin 13. The bonding strength between them becomes higher, and the reliability of the conductive connection state is improved.
In addition, the substrate 111 and the electronic component 121 are absorbed by the elastic deformation (compression deformation) of the bump electrodes 12a and 12b itself even though the bump electrodes 12a and 12b have height (level) variations. Therefore, the bump electrodes 12a and 12b and the terminal 11 are in a good conductive connection state, and therefore, the reliability of the conductive connection state at each contact (connection portion) is improved and the electronic component for the substrate 111 is provided. The mounting strength of 121 is also improved.

  FIG. 7 is a view showing a second embodiment of the electronic component mounting structure of the present invention. The difference between the second embodiment and the first embodiment shown in FIG. 2B is that the height variation between the bump electrodes 12a and 12b is not caused by the production variation of the bump electrode 12 itself. This is due to the design (structure) of the part 121.

  That is, in the mounting structure 20 of the present embodiment, the internal wiring 25 is partially formed on the surface layer portion of the electronic component 121. Therefore, in the electronic component 121, a step 27 is formed between the region 26a where the internal wiring 25 is formed and the region 26b where the internal wiring 25 is not formed. When bump electrodes 12 are formed in one region 26a and the other region 26b, respectively, with such a step 27, even if there is no manufacturing variation between the bump electrodes 12, unevenness ( As a result, the bump electrode 12a formed on the region 26a and the bump electrode 12b formed on the region 26b have different heights (levels) at the top (junction). It will be. That is, there is a height variation between the bump electrodes 12a and 12b.

  Even if there is a variation in height between the bump electrodes 12a and 12b in this way, the mounting structure 20 of the present embodiment has the elastic deformation of the bump electrodes 12a and 12b itself, as in the mounting structure 10 of the first embodiment. Since the variation is absorbed by (compression deformation), the bump electrodes 12a and 12b and the terminal 11 are in a good conductive connection state. Therefore, even in the mounting structure 20 of the present embodiment, the reliability of the conductive connection state at each contact (connection portion) is improved, and the mounting strength of the electronic component 121 on the substrate 111 is also improved.

  In addition, since the height variation between the bump electrodes 12a and 12b due to the unevenness (step 27) of the electronic component 121 can be absorbed in this way, the mounting structure 20 has a higher degree of design freedom for the electronic component 121 than in the past. Can be high. In other words, conventionally, wiring or the like is formed in the surface layer portion on the active surface side of the electronic component because a step is formed on the active surface, which causes the height variation of the bump electrode 12. Although it was avoided, in the mounting structure 20 of the present embodiment, as described above, the bump electrodes 12a and 12b absorb the variations in the height of the bump electrodes 12a and 12b themselves, so that there is a step in the surface layer portion on the active surface side. Even if there is, there will be no hindrance. Therefore, it is sufficiently allowed to form wirings or the like in the surface layer portion on the active surface side.

  When the electronic component 121 has a step 27 as shown in FIG. 7, if the bump electrode 12 is arranged on the step 27, the bump electrode 12 has the topmost portion as shown in FIG. It will not be the center of the joint to the terminal 11 However, in the above-described embodiment, in particular, when the inner resin 13 is substantially hemispherical, even if the center of the joint portion is deviated from the topmost part, it is joined to the terminal 11 under almost the same conditions as when the topmost part is the center. Become. Therefore, a stable conductive connection state with the terminal 11 is ensured.

In the mounting structures 10 and 20, since the terminal 11 is formed by a plating growth method, the terminal 11 is made of an aggregate of metal fine particles, so that the upper surface (bonding surface) of the terminal 11 when viewed microscopically. Is a non-smooth surface having irregularities. However, in the present invention, the inner resin 13 of the bump electrode 12 is elastically deformed, so that the conductive film 14 on the inner resin 13 follows the uneven shape of the upper surface of the terminal 11, whereby the terminal 11 has a non-upper surface. Despite being a smooth surface, it comes into contact with the conductive film 14 over the entire surface.
Therefore, in such mounting structures 10 and 20, the reliability of the conductive connection state at each contact (connection portion) is improved, and the mounting strength of the electronic component 121 on the substrate 111 is also improved.

  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, in the above-described embodiment, the structure of the bump electrode is not substantially hemispherical as shown in FIGS. 2 and 4A, and is almost as shown in FIG. 5A. As shown in FIG. 9, the inner resin 17 is formed in a substantially bowl shape, and a plurality of conductive films 18 are band-like on the upper surface portion along the transverse cross-sectional direction of the inner resin 17. It may be provided. Here, the substantially bowl-like 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 is a curved surface. In addition, about the cross-sectional shape of this substantially bowl-shaped internal resin 17, a substantially semicircle shape may be sufficient and the thing of a substantially trapezoid shape may be sufficient. Even in the bump electrode having such a shape, the height variation may occur due to the manufacturing variation and the structure of the underlying electronic component. In the present invention, such a height variation is the bump electrode. It is designed to be absorbed by itself.

  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.
Further, devices to which the electronic component mounting structure of the present invention is applied are not limited to the above-described liquid crystal display devices, but also organic electroluminescence devices (organic EL devices), plasma display devices, electrophoretic display devices, electron-emitting devices. It can be applied to various electro-optical devices and various electronic modules, such as devices using a field device (Field Emission Display, Surface-Conduction Electron-Emitter Display, etc.).

It is a schematic perspective view which shows typically the structure of the liquid crystal display device to which this invention was applied. It is a principal part enlarged view of 1st Embodiment of the mounting structure which concerns on this invention. (A)-(c) is a perspective sectional view for demonstrating the shape of a terminal. (A) is a perspective view which shows schematic structure of a bump electrode, (b) is a sectional side view. (A) is a perspective view which shows schematic structure of a bump electrode, (b) is a sectional side view. (A) (b) is a figure for demonstrating the mounting structure of 1st Embodiment. It is a figure for demonstrating the mounting structure of 2nd Embodiment. It is a figure for demonstrating the modification of the mounting structure which concerns on this invention. It is a perspective view which shows schematic structure of another bump electrode.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10, 20 ... Mounting structure (electronic component mounting structure), 11 ... Terminal, 12, 12a, 12b ... Bump electrode, 13, 17 ... Internal resin, 14, 18 ... Conductive film, 25 ... Internal wiring, 27 ... Step, DESCRIPTION OF SYMBOLS 100 ... Liquid crystal display device, 110 ... Liquid crystal panel, 111 ... Board | 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 (5)

An electronic component mounting structure in which an electronic component having a bump electrode is mounted on a substrate having a terminal,
A plurality of the bump electrodes and the terminals are provided, and the bump electrodes and the terminals are joined together corresponding to each other.
The plurality of bump electrodes include a structure in which an inner resin is used as a core and the surface thereof is covered with a conductive film, and includes at least two bump electrodes having different joint heights to be joined to the terminals,
The plurality of bump electrodes are bonded to the terminals in a state in which variations in the height of the bonding portions are absorbed by elastic deformation of the internal resins corresponding to the heights of the bonding portions. Electronic component mounting structure characterized by having   2. The electronic component according to claim 1, 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. Mounting structure.   3. The electronic component mounting structure according to claim 2, 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.   4. The electron according to claim 1, 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.   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.

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