JPH11307578A - Bonding method of bump and electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To exclude that a part of bumps can not contribute to connection, by forming a plurality of bumps on the flat outer surface of an electronic component which bumps have flat tip surfaces almost parallel to the outer surface and almost the same height. SOLUTION: Bumps formed on an LSI 10 are pressed against the upper surface of a forming board by applying a specified load to each of the LSI 10, and forming bumps 11a are formed. In this case, pressing is so performed that the upper surface of the forming board and the surface of the LSI 10 become parallel to each other. The forming bumps 11a nave sufficiently flat end surfaces almost equal in height. The LSI 10 is connected with, e.g. a glass substrate 13 of a liquid crystal display panel by COG system. As the result, all the bump 11a are brought closely into contact with facing ITO electrodes 14 in the same state. Thereby it can be excluded that a part of bumps can not contribute to connection.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a bump and a method for bonding an electronic component using the bump.

[0002]

2. Description of the Related Art In recent years, in electronic products, when an electronic component such as a large-scale integrated circuit (hereinafter referred to as LSI) is connected to electrodes of other components constituting the electronic product, LS
A method of forming a bump on an I or the like and connecting via the bump is often used. For example, FIGS. 8 and 9 show a state in which an LSI and a liquid crystal display panel are connected by a COG (Chip On Glass) method, which is one of the connection methods using bumps. 8 and 9, the same members are denoted by the same reference numerals. In these figures, ITO electrodes 2, 2,.
And the bumps 4, 4,... Formed on the LSI 3 are electrically connected via an anisotropic conductive film (Anisotoropic Conductive Film) 6 in which conductive fillers 5, 5,. .

[0003]

However, as shown in FIG. 8, as shown in FIG. 8, bumps 4a whose height is insufficient as compared with other bumps 4,..., And as shown in FIG. If the bumps 4b are present, the space between the bumps and the ITO electrode 2 facing the bumps 4b becomes larger than the particle size of the conductive fillers 5, so that the bumps 4b are not electrically connected. To solve this problem, a method of enlarging the particle size of the conductive fillers 5 is also conceivable. However, if the diameter of the conductive fillers 5 is increased,
Short-circuiting between adjacent bumps is likely to occur, and therefore the pitch between the bumps must be increased, which is not suitable for high-density mounting.

Further, the present invention is not limited to the COG method using an anisotropic conductive film as described above.
ng) method, the film lead inner lead electrode and L
Even when the SI is connected by soldering, a connection failure may occur if the bumps on the LSI side do not have a uniform height or a flat surface.

[0005] In view of the above problems, the present invention provides a bump capable of obtaining a good connection state and suitable for high-density mounting, a method of forming a bump capable of obtaining such a bump, and a method of forming a bump. An object of the present invention is to provide a bonding method capable of reliably obtaining an electrical connection by using the bump of the present invention.

[0006]

In order to solve the above-mentioned problems, the invention according to claim 1 of the present invention comprises a plurality of electronic components formed on a flat outer surface to electrically connect with the electronic components. Are connected to the bumps, each having a flat tip surface substantially parallel to the outer surface, and
It is characterized in that they have substantially the same height.

According to the first aspect of the present invention, the plurality of bumps formed on the flat outer surface of the electronic component have flat end faces substantially parallel to the outer surface, respectively, and Since these bumps have the same height, when this electronic component is connected to other components via these bumps, all the bumps are in the same state with respect to the electrodes of the other components. Adhesion can be made, and there is no occurrence that some of the bumps cannot contribute to the connection, and a good connection state can be obtained as the entire electronic component.
In addition, even in the case where the bump and the electrode of another component are connected with conductive particles interposed therebetween, the bump can be connected in a good state regardless of the particle size of the conductive particle. It is not necessary to increase the pitch between the bumps, and the bump is suitable for high-density mounting.

Here, the electronic component may have any outer surface on which a bump can be formed and can be electrically connected to another component or the like via the bump. For example, a large-scale integrated circuit (LSI) ) And the like. The bump is made of a material generally used as a bump material, for example, gold, copper, or solder.

According to a second aspect of the present invention, in the bump according to the first aspect, the flat tip surface is substantially flat in which either a convex portion or a concave portion is uniformly formed on the flat surface. It is characterized by a simple tip surface.

According to the second aspect of the invention, in addition to the effect of the first aspect, since the convex portions or the concave portions are formed evenly on the flat surface, the bumps can be further strengthened. It becomes a bump that can be connected. Specifically, for example, when using an anisotropic conductive film and indirectly connecting a bump and an electrode of another component via conductive particles in the anisotropic conductive film, the bump is formed by a convex portion. When the conductive particles fit into the recesses or the recesses to be formed, the individual conductive particles are fixed and connected more reliably. In the case where the bump and the electrode of another component are directly connected, the convex portion or the convex portion separated by the concave portion is in a state where the electrode bites into the electrode and is more reliably connected. .

Here, examples of the protruding portion include linear or curved ridges and projections, and examples of the recessed portion include linear or curved grooves and depressions. . Further, it is preferable that the convex portions and the concave portions are not formed locally on the end face, but are formed almost uniformly on the end face. Specifically, it may be formed in a lattice shape or a spiral shape.

The size and shape of the projections and depressions may be appropriately changed according to the specific connection method between the bumps and the electrodes of other components. For example, the pump is connected to the electrodes of other parts,
When the connection is made using conductive particles of an anisotropic conductive film, the conductive particles come into contact with both the bump and the electrode when the conductive particles enter the recess formed by the convex portion or the concave portion. The size and shape as possible. In the case where the bump is directly connected to the electrode, a convex portion,
The convex portion separated by the concave portion has a wide shape so that the electrode can bite without damaging the electrode and a required contact area can be obtained.

According to a third aspect of the present invention, there is provided an electronic component bonding method for connecting an electronic component to another component in a conductive manner through a plurality of bumps formed on a flat outer surface of the electronic component. A molding table having a flat molding surface is prepared, and a plurality of bump tip surfaces are pressed against the molding surface while the outer surface of the electronic component is kept parallel to the molding surface to form a flat surface. Then, the plurality of bumps and the electrodes are electrically connected to each other in a state where the outer surface of the electronic component and the surface of the electrode of the other component are substantially parallel to each other.

According to the electronic component bonding method of the present invention, a flat bump tip surface can be easily formed, and a highly reliable conductive connection can be stably obtained.

Here, the other component connected to the electronic component is, for example, a glass substrate of a liquid crystal display panel driven by an LSI which is an electronic component, and the electrodes are ITO formed on the glass substrate. And the like. When the connection is made by the TAB method, the other components are a film carrier tape, and the electrodes are inner leads of the film carrier tape.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. (First Embodiment) An example of a method for forming a bump according to the present invention is shown in FIGS. In these figures, 10 is an LSI (large-scale integrated circuit), 12 is a forming plate, 1
3 is a glass substrate of the LCD panel.

First, bumps are formed on a flat surface (outer surface) 10a of an LSI 10, which is an electronic component, by using a conventional bump forming method. Specifically, a first metal layer made of titanium, chromium, or the like, a second metal layer made of tungsten, platinum, silver, or the like is formed on the surface 10a, and a barrier metal layer made of these metal layers is formed. Next, on the barrier metal layer, by electrolytic plating,
The bumps 11, 11, 11 made of gold (Au) are formed. The bumps 11 are formed at positions that are electrically connected to a circuit (not shown) inside the LSI 10. Bump 1
As shown in FIG. 1, 1, 11, 11 are not uniform in height, and the end faces 18 are formed with irregularities.

Next, a forming plate 12 (plate member) is prepared. The forming plate 12 is a flat plate made of a metal harder than gold and having a certain thickness, which is processed to have a sufficient flatness. The bumps 11, 11, and 11 formed on the LSI 10 are pressed against the upper surface of the forming plate 12 by applying a predetermined load to the entire LSI 10 (in the direction of the arrow in FIG. 1). In this case, the upper surface of the forming plate 12 and the upper surface 1 of the LSI 10
0a are pressed in a state where they are parallel to each other, and at this time, if necessary, heating is performed. Thereafter, when the forming plate 12 and the LSI 10 are separated from each other, as shown in FIG.
a and 11a are obtained. These forming bumps 11
a... have substantially the same height and the end faces 18
Are flattened by being crushed on the flat surface of the forming plate 12 to form sufficiently flat end faces 18a.

Next, the LSI 10 of FIG. 2 and a glass substrate (other components) 13 of the liquid crystal display panel are connected by the COG method. On the glass substrate 13, ITO (Indium Tin)
Oxide) The electrodes 14, 14, 14 are formed and the IT
The O-electrodes 14 have a sufficiently flat surface and substantially the same height as each other (FIG. 3). These ITO electrodes 14, 14,
The conductive filler (conductive particles) 16 is formed on the resin 1
The anisotropic conductive film (conductive member) 17 dispersed in Step 5 is placed.

The conductive filler 16 contained in the anisotropic conductive film 17 is a metal particle such as nickel, a carbon particle, a plastic particle coated with a metal film, or the like, and has a particle size of about 10 μm. The binder resin that holds the conductive filler 16 in a dispersed state is a resin having an adhesive property, such as a thermoplastic resin such as a polyethylene resin or a thermosetting resin such as an epoxy resin. Further, the anisotropic conductive film 17 may contain a dispersing agent such as silica, if necessary.

Next, the individual forming bumps 11a shown in FIG.
, So as to come to the position corresponding to each of
When the position is determined, the LSI
10 is heated and pressed from above by a bonding tool (not shown) under predetermined conditions. After the elapse of a predetermined time from the start of the heating and pressurization, when the bonding tool is removed, as shown in FIG.
and the ITO electrodes 14 are connected via conductive fillers 16 in the anisotropic conductive film 17.

The above-described forming bump 11 of the present invention
According to a, 11a, and 11a, since the heights are almost the same and the end surfaces 18a are sufficiently flat, the glass electrodes 14, 14, having flat and uniform heights are provided.
14 and all the forming bumps 11a
Can be brought into close contact with the opposing glass electrode 14 in the same state, and the LSI 10 and the glass substrate 13 are in a good connection state, and are reliably connected electrically.

(Second Embodiment) Another example of the bump forming method of the present invention is shown in FIGS. In these figures, 20 is an LSI and 22 is a forming plate.
The same reference numerals as in the first embodiment denote the glass substrate, the ITO electrode, the anisotropic conductive film, and the like of the LCD panel. First, on the flat surface (outer surface) 20a of the LSI 20,
The bumps 21, 21, 21 are formed as in the first embodiment. The bumps 21 are formed at positions electrically connected to a circuit (not shown) inside the LSI 20. Further, as shown in FIG. 4, the bumps 21 are not uniform in height or have bumps on the end faces 28.

Next, a forming plate (plate member) 22 is prepared. The forming plate 22 is a flat plate made of a metal harder than gold. As shown in FIG. 7, ridges 22a, 22a... The protruding ridges 22a are all the same height, have a substantially triangular cross-sectional shape, and are formed such that their widths are substantially the same as the particle size of the conductive fillers 16 described below.
Besides, the main surface forming the upper surface of the forming plate 22 other than the protrusions 22a is processed so as to have a sufficient flatness.

With respect to the upper surface of the forming plate 22,
The bumps 21, 21, 21 formed on the LSI 20 are
The entire LSI 20 is pressed in the same manner as in the first embodiment (in the direction of the arrow in FIG. 4). In this case, the forming plate 22
Is pressed and, if necessary, heated in such a state that the main surface of the upper surface of the device 20 and the surface 20a of the LSI 20 are parallel to each other. After that, the forming plate 22 and the LSI
By separating them from each other, forming bumps 21a, 21a, 21a are obtained as shown in FIG. These forming bumps 21a have substantially the same height,
In addition, irregularities and the like on the end surfaces 28.
Are sufficiently flattened by being crushed by the main surface of the upper surface of the ridge 22a of the forming plate 22.
Are formed, but most other surfaces are flat, and substantially flat end surfaces 28a are formed.
Will be provided.

Next, the LSI 20 of FIG. 5 and the glass substrate (other components) 13 of the liquid crystal display panel are connected by the COG method. On a glass substrate 13, ITO electrodes 14, 1
4 and 14 are formed, and the ITO electrodes 14 have a sufficiently flat surface and substantially the same height as each other. ITO
Electrodes 14, 14, 14 and forming bumps 21a,
21a and 21a are connected via the anisotropic conductive film 17, as shown in FIG. 6, in the same manner as in the first embodiment. By this connection process, the forming bump 2
1a are formed in the grooves 21b.
The conductive fillers 16, 16,...

The above-described forming bump 21 of the present invention
According to a, 21a, and 21a, since the heights are almost the same and the end surfaces 28a are sufficiently flat, the glass electrodes 14, 14, having flat and uniform heights are provided.
14 and all the forming bumps 21a
Can be brought into close contact with the opposing glass electrode 14 in the same state, and the conductive filler 16
, The conductive filler 16 is trapped and fixed by the grooves 21b, so that the conductive filler 16 moves during heating and pressing, resulting in an uneven distribution state. Is prevented, the LSI 20 and the glass substrate 13 are always in a good connection state, and the connection is made more reliably electrically. In addition, conductive filler 16 ...
Are easily fixed between the forming bumps 21a and the ITO electrodes 14, so that the number of conductive fillers 16 involved in the connection increases, and the forming bumps 2
And the resistance between the ITO electrodes 14 becomes small.

Note that C in the first and second embodiments described above.
In the connection of the OG system, an anisotropic conductive film is used as a material for electrically connecting the bump to the ITO electrode. However, the present invention is not limited to this. For example, a conductive paste such as a silver-based paste is applied to the bump. The present invention can be applied to various methods such as a connection method and a method using a plastic ball as a conductive layer.

(Other Embodiments) When mounting by the TAB method, forming bumps are formed on the LSI by the same method as in the first or second embodiment, and the forming bumps are formed. If the bumps are connected to the lead electrodes of the film carrier using a eutectic alloying reaction or thermocompression bonding, the bumps can be connected in good condition because the height of each bump is uniform. Further, when mounting by the TAB method, instead of using the forming plate 22 in the second embodiment, a forming plate in which a plurality of grooves intersect in a lattice pattern on the upper surface is used. Forming bumps are formed in the same manner as in the first embodiment. In this case, a convex portion corresponding to the groove of the forming plate is formed on the forming bump. If such a forming bump is connected to a lead electrode, the height of each bump is uniform and, in addition, the bumps are formed with protrusions of the same height. The surface of the electrode is bitely contacted to provide a strong and stable connection.

In addition, the present invention relates to a COF (Chip On Fil
m) It is useful for various mounting methods such as the method of connecting via bumps.

[0031]

According to the first aspect of the present invention, when an electronic component is connected to another component via these bumps, all the bumps are connected to the electrodes of the other component. ,
Contact can be made in the same state, and there is no occurrence that some of the bumps cannot contribute to the connection, and a good connection state can be obtained. In addition, even in the case where the bump and the electrode of another component are connected with conductive particles interposed therebetween, the bump can be connected in a good state regardless of the particle size of the conductive particle. It is not necessary to increase the pitch between the bumps, and the bump is suitable for high-density mounting.

According to the invention described in claim 2, according to claim 1
In addition to the effects described above, the bumps or recesses are further formed on the front end surface of the bumps, so that the bumps can be further strongly connected.

According to the third aspect of the present invention, the front end surface of the bump can be easily flattened, and a highly reliable conductive connection between electronic components can be stably obtained through the bump. it can.

According to the fourth aspect of the present invention, a substantially flat bump tip surface in which unevenness is evenly formed on a flat surface can be easily formed, and a more reliable conductive connection can be stably performed. Can be obtained.

According to the fifth aspect of the present invention, since the anisotropic conductive film is interposed between the connection electrode and the bump having the concave portion formed on the tip end surface, the bump and the connection electrode can be more reliably electrically connected. Connected.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of a method for forming a bump according to the present invention.

FIG. 2 is a sectional view showing a bump obtained by the bump forming method of FIG. 1;

FIG. 3 is a cross-sectional view showing a state where the bumps of FIG. 2 are connected to ITO electrodes.

FIG. 4 is a cross-sectional view showing another example of the bump forming method of the present invention.

FIG. 5 is a sectional view showing a bump obtained by the bump forming method of FIG. 4;

FIG. 6 is a cross-sectional view showing a state where the bumps of FIG. 5 are connected to ITO electrodes.

FIG. 7 is a perspective view showing a forming plate used in the bump forming method of FIG. 4;

FIG. 8 is a cross-sectional view showing an example of a conventional connection state between a bump and an ITO electrode.

FIG. 9 is a cross-sectional view showing another example of a conventional connection state between a bump and an ITO electrode.

[Explanation of symbols]

 10, 20 LSI (electronic component) 11, 21 Bump 11a, 21a Forming bump 21b Groove (concave) 12, 22 Forming plate (plate member) 22a Ridge (convex) 13 Glass substrate (other components) 14 ITO electrode ( Electrodes of other parts) 15 Resin 16 Conductive filler (conductive particles) 17 Anisotropic conductive film (conductive member) 18, 28 End face

Claims (5)

[Claims] 1. A plurality of bumps, which are formed on a flat outer surface of an electronic component and are electrically connected to the electronic component, each of which has a flat tip surface substantially parallel to the outer surface. A bump having a height that is substantially the same as each other. 2. The flat end surface according to claim 1, wherein the flat end surface is a substantially flat end surface in which one of a convex portion and a concave portion is formed uniformly. bump. 3. A method for bonding an electronic component to another component via a plurality of bumps formed on a flat outer surface of the electronic component in a conductive manner, the method comprising bonding a flat molded surface. Preparing a molding table provided with, the outer surface of the electronic component is pressed against the molding surface while pressing the plurality of bump tip surfaces against the molding surface while maintaining a state parallel to the molding surface, and thereafter, A method of bonding an electronic component, wherein the plurality of bumps and the electrode are conductively connected with an outer surface of the electronic component and a surface of an electrode of the other component being substantially parallel to each other. 4. A molding table having a substantially flat molding surface in which projections or depressions are uniformly formed on a flat surface is used as the molding table, and the projections or depressions are uniformly formed on the bump tip surface. 4. The method for bonding electronic components according to claim 3, wherein the bonding is performed on a substantially flat surface. 5. A substantially flat tip surface in which the bump tip is formed evenly on a flat surface by using a molding table having a molding surface on which a projection is uniformly formed on a flat surface. 5. The electronic component according to claim 4, wherein the bump of the electronic component and the electrode of the other component are electrically connected to each other through an anisotropic conductive film containing conductive particles. Bonding method.