JPH10163258A - Bump, and method and apparatus for forming bump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form bumps high and having less height variation, and to provide a bump shape and a bump forming method capable of preventing melted solder from flowing out to its periphery at the time of soldering. SOLUTION: Metal bumps 34 projecting on the electrode surfaces of a surface mounting type electronic component are formed by press-bonding one end of a metal wire 13 projecting from the tip of a capillary 36 to the tip of the capillary between the tip of the capillary and the surface of each electrode 92a, with a capillary having truncated conical or columnar recession having an inside diameter larger than a capillary hole at the tip part of the capillary 36, and cutting the other end of the metal wire 13 after that.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming electrodes on a surface-mounted electronic component on an electrode of the surface-mounted electronic component in order to directly connect the electrodes of the electronic component to the electrodes of a circuit board by soldering or a conductive adhesive. The present invention relates to a bump structure and a method for forming the bump.

[0002]

2. Description of the Related Art As means for high-density mounting of electronic components on a printed circuit board (hereinafter simply referred to as a substrate), electrodes of an integrated circuit chip (hereinafter simply referred to as a chip) and electrodes of a substrate (referred to as lands) are directly connected. There is a flip chip method of soldering (or bonding with an adhesive). In this method, a projection called a bump is provided on an electrode of a chip in advance, and the two are connected by overlapping and heating so as to match a solder (or an adhesive) provided on a land of a substrate.

FIG. 9 is a view for explaining a conventional capillary for forming a bump, the shape of a bump, and a forming method.
3A is a cross-sectional view of a bump forming capillary, FIG. 3B is a cross-sectional view illustrating a bump forming method, and FIG. 3C is a cross-sectional view of a bump.
10A and 10B are views for explaining a conventional method of soldering a chip to a substrate, wherein FIG. 10A is a cross-sectional view showing a positional relationship before soldering to the substrate, and FIG. It is sectional drawing which shows the positional relationship of. Hereinafter, description will be made with reference to the drawings.

Reference numeral 92 denotes an integrated circuit chip having an electrode 92a of aluminum or the like for soldering to a land 91a of a substrate 91. Reference numeral 94 denotes a bump made of gold, aluminum, or the like provided on the electrode 92a of the chip 92. Reference numeral 91 denotes a substrate on which electronic components and the like are mounted, and has a land 91a for soldering to a bump 94 on a chip 92. As shown in FIG. 9A, the capillary 96 is provided with a capillary hole 96a through which a wire 93 of aluminum or the like passes, and a molten ball at the tip of the wire 93 is connected to the bottom 96b of the capillary 96 and the electrode of the chip 92 at the time of ball bonding. FIG.
Pressing is performed as shown in FIG. 9B (ultrasonic bonding), and the extra wires 93 are torn off to complete the bumps 94 as shown in FIG. 9C. Note that there is also a method of forming the bumps 94 by plating the electrodes 92a with gold, solder, or the like.

Next, the solder 91c provided on the lands 91a of the substrate 91 and the bumps 94 on the chip 92 are overlapped so as to coincide with each other, and the entire substrate or the connection portion is heated to melt the solder. Then, by fixing both, the soldering of the chip 92 to the substrate 91 is completed.

[0006]

When bumps 94 are formed on a chip 92 by a ball bonding method, a cutting position 94a when the wire 93 is torn off after bonding.
However, there is a problem that the height of the plurality of bumps 94 varies greatly. Further, when bumps are formed on the chip by plating, the height of the bumps 94 becomes constant, but it is difficult to form the bumps 94 thickly. Are easily spread along the bumps 94, and there is a problem that a high-density terminal is short-circuited with an adjacent electrode.

SUMMARY OF THE INVENTION An object of the present invention is to provide a bump shape, a bump forming method, and a bump forming apparatus which form a bump having a small height variation and in which molten solder does not flow out to the periphery during soldering. I do.

[0008]

In order to achieve the above object, the present invention relates to a bump formed on an electrode surface of a surface mount type electronic component, wherein the bump has a truncated conical or cylindrical projection. It is characterized by being formed. Further, in the bumps protruding from the electrode surface of the surface mount electronic component, a wall is formed on an outer peripheral portion of the bumps.

Further, in a bump formed on an electrode surface of a surface mount type electronic component, a first bump formed by projecting the bump on the electrode surface and a first bump formed on the first bump and having a smaller height than the first bump. And a second bump having a small cross-sectional area. Further, the bump is made of a metal wire coated with solder.

Further, the first bump or the second bump is formed by a plating method or a ball bonding method. In addition, the bumps projecting from the electrode surface of the surface mount electronic component are formed by a wedge bonding method. Further, after crimping one end of a metal wire protruding from a tip end of a capillary having a capillary hole between the tip end of the capillary and the electrode surface, cutting the other end of the metal wire to project on the electrode surface. In the bump forming method of forming a portion, a truncated conical or columnar concave portion having an inner diameter larger than the inner diameter of the capillary hole communicating with the capillary hole is provided at the tip of the capillary. It is a feature.

Further, after one end of a metal wire protruding from the tip of a capillary having a capillary hole is pressed between the tip of the capillary and the surface of the electrode, the other end of the metal wire is cut to form the electrode. In the bump forming method for forming a convex portion on a surface, a constriction having an inner diameter smaller than the inner diameter of the capillary hole is provided at a predetermined position of the capillary hole.

Further, one end of a metal wire protruding from the tip of a capillary having a capillary hole is pressed between the tip of the capillary and the surface of the electrode, and then the other end of the metal wire is cut to form the electrode. In the bump forming method for forming a convex portion on the surface, a concave portion having a diameter smaller than an outer diameter of the bump is provided at a tip portion of the capillary.

Further, one end of a metal wire protruding from a tip end of a capillary having a capillary hole is pressed between the tip end of the capillary and the surface of the electrode, and the other end of the metal wire is cut to form the electrode. In a bump forming method for forming a convex portion on a surface, a shaped die having a concave portion having a predetermined shape is pressed against a bump formed on an electrode surface of the surface-mounted electronic component, and an upper portion of the bump is pressed by a predetermined amount. It is characterized by shaping into a convex part of a shape.

Further, one end of a metal wire protruding from the tip of a capillary having a capillary hole is pressed between the tip of the capillary and the surface of the electrode, and then the other end of the metal wire is cut to form the electrode. In a bump forming apparatus for forming a projection on a surface, a cutter for cutting the other end of the metal wire is provided at a position corresponding to a tip of the capillary.

[0015]

1A and 1B are diagrams for explaining a bump shape and a forming method according to a first embodiment of the present invention. FIG. 1A is a diagram showing a bump forming method, and FIG. 1B is a transverse sectional view of the bump. (C) is a longitudinal sectional view of the bump. Hereinafter, description will be made with reference to the drawings.
Note that the purpose of this example is to form a high bump without increasing the bottom area of the bump.

Reference numeral 92 denotes an integrated circuit chip having electrodes 92a made of aluminum or the like for soldering to lands 91a of the substrate 91. Reference numeral 14 denotes a bump made of aluminum or the like provided on the electrode 92a of the chip 92 by a wedge bonding method. 9
Reference numeral 1 denotes a substrate on which electronic components and the like are mounted, and lands 91 for soldering to the bumps 14 on the electrodes 92a of the chip 92.
a.

Next, a method of forming the bump 14 and the substrate 91
A method for soldering to a substrate will be described. Electrode 9 of chip 92
An aluminum wire 13 is placed on 2a, and a wedge 16 is applied to the upper portion of the wire 13 as shown in FIG. After bonding, excess wires 13 are torn off to form bumps 14. The bumps 14 extend in the length direction of the electrode 92a, and have a long cross section as shown in FIG. 1B, but a vertical section in which the positional relationship with the adjacent electrode is a problem, as shown in FIG. It can be expensive. The solder 91c provided on the lands 91a of the board 91 and the bumps 14 on the chip 92 are overlapped so as to coincide with each other, and the entire board or a locally connected portion is heated to melt the solder and fix the both. Thereby, the soldering of the chip 92 to the substrate 91 is completed.

As described above, in this embodiment, the height of the bumps can be made substantially equal to the wire diameter, and the wires can be widened in parallel with the adjacent electrodes. No flow and no short circuit failure. FIGS. 2A and 2B are diagrams for explaining the shape and formation method of the bump according to the second embodiment of the present invention. FIG. 2A is a cross-sectional view showing the shape of a first bump formed by plating, and FIG. It is sectional drawing which shows the shape of a completed bump. (C) is a cross-sectional view showing the shape of the first bump formed by the ball bonding method, and (d) is a cross-sectional view showing the shape of the completed bump formed by the ball bonding method. Hereinafter, description will be made with reference to the drawings.
Note that the purpose of this example is to form a high bump without increasing the bottom area of the bump.

Numeral 24 denotes bumps provided in two steps on the electrodes 92a of the chip 92, such as a first bump 24a made of gold or the like provided by plating and a solder or the like provided by plating on the first bump 24a. It is composed of the second bump 24b. Since the chip 92 has the same name, function and operation as those of the first embodiment, the same reference numerals are given and the description is omitted.

First, the first bumps 24a are provided on the electrodes 92a of the chip 92 by a plating method, and the second bumps 24b are formed thereon by further plating the solder. By performing plating in two steps in this manner, the height of the bump 24 can be made higher than that of a conventional bump. The solder provided on the lands of the substrate and the bumps 24 on the chip 92 side are overlapped so as to coincide with each other, and the entire substrate or a locally connected portion is heated to melt the solder, thereby fixing the two. Is completed. In addition, FIG. 2 (c), (d)
As described above, the same effect can be obtained by forming the first bump 25a by a ball bonding method instead of the plating method and forming the second bump 25b by a ball bonding method.

As described above, in this embodiment, the height of the bump can be increased by forming the bump in two steps.
At the time of soldering, the molten solder does not flow in the direction of the adjacent electrodes, and no short circuit fault occurs. Further, since the bumps are high, mechanical stress between the substrate and the chip can be released.
FIG. 3 is a view for explaining a bump forming capillary, a bump shape and a forming method according to a third embodiment of the present invention.
(A) is a sectional view of a capillary for forming a truncated cone-shaped bump,
(B) is a sectional view showing a bump forming method, and (c) is a sectional view of the bump. (D) is a sectional view of a capillary for forming a cylindrical bump, and (e) is a sectional view of the bump. Hereinafter, description will be made with reference to the drawings. The purpose of this example is to form a high bump without increasing the bottom area of the bump, and to reduce variations in the shape and height of the bump.

Reference numeral 34 denotes a bump made of aluminum or the like provided on the electrode 92a of the chip 92 by a ball bonding method. Since the chip 92 has the same name, function and operation as those of the first embodiment, the same reference numerals are given and the description is omitted.
First, the shape of the capillary 36 will be described. As shown in FIG. 3A, the capillary hole 36a through which the aluminum wire passes is provided with a truncated conical recess 36b at the tip. At the time of ball bonding, the ball melted at the tip of the wire 13 has a truncated conical recess 36 b and the electrode 9 of the chip 92.
3B, the bumps 34 are completed as shown in FIG. 3C. The bumps 34 can have the same bottom size as the conventional bumps and the height of the bumps can be made higher, and the shape of the bumps 34 can be made constant by the depressions 36b of the capillary 36. The solder provided on the lands of the substrate and the bumps 34 on the chip 92 are overlapped so as to coincide with each other, and the entire substrate or a locally connected portion is heated to melt the solder, thereby fixing the two. Is completed.

By performing ball bonding using a capillary 37 having a cylindrical recess 37b at the tip of a capillary hole 37a as shown in FIG. 3D, a cylindrical bump as shown in FIG. 35 can be formed. The same effect as that of the above-described truncated conical bump 34 can be obtained by the bump 35. As described above, in the present embodiment, the height of the bump can be increased and the variation can be reduced by providing a recess having a predetermined shape inside the capillary hole of the capillary. As a result, at the time of soldering, the molten solder does not flow in the direction of the adjacent electrodes, and no short circuit fault occurs. Further, since the bumps are high, mechanical stress between the substrate and the chip can be released.

FIG. 4 is a view for explaining a bump-forming capillary, a bump shape and a forming method according to a fourth embodiment of the present invention. FIG. 4A is a sectional view of the bump-forming capillary.
(B) is a sectional view showing a bump forming method, and (c) is a sectional view of the bump. Hereinafter, description will be made with reference to the drawings. The purpose of this example is to form a high bump without increasing the bottom area of the bump, and to reduce variations in the shape and height of the bump.

Reference numeral 44 denotes a bump made of aluminum or the like provided on the electrode 92a of the chip 92 by a ball bonding method. Since the chip 92 has the same name, function and operation as those of the first embodiment, the same reference numerals are given and the description is omitted.
First, the shape of the capillary 46 will be described. At the tip of the capillary hole 46a through which the aluminum wire 13 passes, FIG.
A concavity 46b is provided concentrically as shown in FIG. At the time of ball bonding, the ball melted at the tip of the wire 13
4B is pressed between the electrode 92a of the chip 92 and the projection 92b on the outer periphery as shown in FIG. 4C.
Is completed. The solder provided on the lands of the substrate and the bumps 44 on the chip 92 are overlapped so as to coincide with each other, and the entire substrate or a locally connected portion is heated to melt the solder, thereby fixing the two.
Is completed. The protrusions (walls) 44b on the outer periphery of the bumps 44 prevent the flow of the molten solder, which is advantageous for high-density terminal attachment.

As described above, in the present embodiment, a projection can be formed on the outer periphery of the bump by providing a depression at the tip of the capillary, and the outflow of molten solder during soldering can be prevented.
Short-circuit defects with adjacent terminals can be eliminated. 5 (a) and 5 (b) are views for explaining a bump-forming capillary, a bump shape and a forming method according to a fifth embodiment of the present invention. FIG. 5 (a) is a cross-sectional view of the bump-forming capillary, and FIG. And (c) is a cross-sectional view of the bump. Hereinafter, description will be made with reference to the drawings. The purpose of this example is to form a high bump without increasing the bottom area of the bump, and to reduce variations in the shape and height of the bump.

Reference numeral 54 denotes a bump made of aluminum or the like provided on the electrode 92a of the chip 92 by a ball bonding method. Since the chip 92 has the same name, function and operation as those of the first embodiment, the same reference numerals are given and the description is omitted.
First, the shape of the capillary 56 will be described. As shown in FIG. 5 (a), the capillary hole 56a through which the aluminum wire passes has a cylindrical dent 56b at the tip and a circumferential protrusion 56c at the base of the cylindrical dent 56b on the capillary hole 56a side such that the inner diameter becomes small. Is provided. In the ball bonding, the ball melted at the tip of the wire 13 is pressed between the cylindrical recess 56b and the electrode 92a of the chip 92 as shown in FIG. At this time, the capillary 5
6 is extremely narrowed at the tip end 54a of the bump 54 completed by the protrusion 56c. When the wire 13 is torn off after the ball bonding, the wire 13 is cut at the narrowed portion, and the wire 13 is cut off as shown in FIG. The bump 54 is completed. Since the height of the bump 54 is determined by the position of the protrusion 56c, the variation can be reduced as compared with the conventional bump.

As described above, in the present embodiment, by providing a projection at a predetermined position inside the capillary hole of the capillary, the cutting position of the wire is fixed and the variation in the height of the bump is reduced. FIG. 6 is a view for explaining a bump forming apparatus and a bump shape according to a sixth embodiment of the present invention.
(A) is a sectional view showing a bump forming apparatus, and (b) is a sectional view showing a shape of a bump. Hereinafter, description will be made with reference to the drawings. The purpose of this example is to reduce the variation in bump height.

Reference numeral 64 denotes a bump made of aluminum or the like provided on the electrode 92a of the chip 92 by a ball bonding method. Since the chip 92 has the same name, function and operation as those of the first embodiment, the same reference numerals are given and the description is omitted.
First, the shape of the capillary 66 will be described. A cylindrical recess 66b is provided at the tip of a capillary hole 66a through which the aluminum wire 13 passes. At the time of ball bonding, the ball melted at the tip of the wire 13 is pressed between the cylindrical recess 66b and the electrode 92a of the chip 92 as shown in FIG. Thereafter, the capillary 66 is pulled up, and the wire 13 is cut by the cutter 67.
The bump 64 is completed as shown in FIG. This bump 64
Can reduce the variation in height as compared with the conventional bump. Note that the cutter 67 operates so as to cut the wire 13 when the capillary 66 is pulled up by a link mechanism or the like interlocking with the raising operation of the capillary 66.

As described above, in this embodiment, since the wire is cut by the cutter at a predetermined position after the ball bonding, the cut position of the wire is fixed, and the variation in the height of the bump is reduced. 7A and 7B are views for explaining the shape of a bump-forming wire and a bump according to a seventh embodiment of the present invention. FIG. 7A is a cross-sectional view of the bump-forming wire, and FIG. FIG. 3C is a cross-sectional view of a bump formed by a wedge bonding method. Hereinafter, description will be made with reference to the drawings. It is to be noted that the purpose of this embodiment is to simplify the assembling process because it is not necessary to supply solder when soldering to a substrate.

Reference numeral 73 denotes a wire in which an aluminum core wire 73a is covered with a solder 73b. 74 is an electrode 92 of the chip 92
a is a bump provided on a by a ball bonding method. Reference numeral 75 denotes a bump provided on the electrode 92a of the chip 92 by a wedge bonding method. Since the chip 92 has the same name, function and operation as those of the first embodiment, the same reference numerals are given and the description is omitted.

The solder-coated aluminum wire 73 is ball-bonded to the electrode 92a of the chip 92, and the wire 73 is cut at a predetermined position (see FIG. 7B). The bumps 75 are formed by a wedge bonding method using the solder-coated aluminum wires 73. (See FIG. 7 (c)). Solder provided on land of substrate and bump 7 on chip 92 side
The soldering of the chip 92 to the substrate is completed by overlapping the substrates 4 or 75 so that the solder is melted by heating the entire substrate or the connection portion locally or locally to fix the two.

At this time, since the solder 73b covering the aluminum wire 73a is melted and sufficient solder can be supplied at the time of soldering to the substrate, the reliability of soldering is improved. As described above, in the present embodiment, when soldering to the board, the solder covering the wire is melted, the supply amount of the solder is increased, and the reliability of the soldering is improved. 8A and 8B are diagrams for explaining a bump shaping jig, a leveling step, and a bump shape according to an eighth embodiment of the present invention. FIG. 8A is a cross-sectional view of the leveling jig, and FIG. Sectional view,
(C) is a sectional view of the bump. Hereinafter, description will be made with reference to the drawings. The purpose of this example is to make the shape and height of the bumps constant.

Reference numeral 84 denotes a bump made of aluminum or the like provided on the electrode 92a of the chip 92 by a ball bonding method. Reference numeral 85 denotes a bump shaped by the leveling jig 87. Since the chip 92 has the same name, function and operation as those of the first embodiment, the same reference numerals are given and the description is omitted. First, a wire is ball-bonded on the electrode 92a of the chip 92 by a normal ball bonding method.
Then, a bump 84 is shaped by applying pressure as shown in FIG. 8B using a leveling jig 87 shown in FIG. 8A. Thus, a bump 85 having a predetermined shape as shown in FIG. 3C is completed. In this method, the leveling jig 8
Since the shape of the tip portion 85a of the bump 85 is determined by the concave portion 87a of 7, the height is constant.

As described above, in this embodiment, since the shape and height of the bumps are constant, soldering to the substrate can be performed stably.

[0036]

As described above, according to the present invention, the height of the bumps is increased, and the shape and forming method of the bumps in which the molten solder is not diffused to the periphery at the time of soldering is provided. Becomes possible.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a bump shape and a forming method according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining a bump shape and a forming method according to a second embodiment of the present invention.

FIG. 3 is a diagram for explaining a bump-forming capillary, a bump shape, and a forming method according to a third embodiment of the present invention.

FIG. 4 is a view for explaining a bump forming capillary, a bump shape and a forming method according to a fourth embodiment of the present invention.

FIG. 5 is a view for explaining a bump forming capillary, a bump shape and a forming method according to a fifth embodiment of the present invention.

FIG. 6 is a diagram for explaining a bump forming apparatus and a bump shape according to a sixth embodiment of the present invention.

FIG. 7 is a view for explaining shapes of bump forming wires and bumps according to a seventh embodiment of the present invention.

FIG. 8 is a view for explaining a bump shaping jig, a leveling step, and a bump shape according to an eighth embodiment of the present invention.

FIG. 9 is a diagram for explaining a conventional capillary for forming a bump, a shape of a bump, and a forming method.

FIG. 10 is a view for explaining a conventional method of soldering a chip to a substrate.

[Explanation of symbols]

91 ··· substrate, 16 ··· wedge, 91a ··· land, 67 ·
... Cutter, 91b ... Solder,
36b, 37b, recess, 92, tip
13, 73... Wire, 92a
..Electrode, 87 ........ Leveling jig, 14, 24, 34, 44, 54, 64, 74, 7
5, 85 ... bumps, 36, 46, 56, 66 ...
・ ・ Capillary.

Claims (11)

[Claims] 1. A bump protruding from an electrode surface of a surface mount electronic component, wherein the bump is formed in a truncated cone or a column. 2. A bump formed on an electrode surface of a surface-mounted electronic component, wherein the bump is formed by forming a wall around an outer peripheral portion of the bump. 3. A bump formed on the surface of an electrode of a surface-mounted electronic component, wherein the first bump is formed on the surface of the electrode and the first bump is formed on the first bump rather than the first bump. A second bump having a small cross-sectional area. 4. The bump according to claim 1, wherein the bump is formed of a metal wire coated with solder. 5. The bump according to claim 3, wherein the first bump or the second bump is formed by a plating method or a ball bonding method. 6. A bump characterized in that a bump projecting from an electrode surface of a surface mount electronic component is formed by a wedge bonding method. 7. An end of a metal wire protruding from a tip end of a capillary having a capillary hole is pressed between the tip end of the capillary and the electrode surface, and the other end of the metal wire is cut off to form the electrode. In the bump forming method of forming a convex portion on the surface, a truncated conical or cylindrical concave portion having an inner diameter larger than the inner diameter of the capillary hole communicating with the capillary hole is provided at the tip of the capillary. A bump forming method. 8. After crimping one end of a metal wire protruding from the tip of a capillary having a capillary hole between the tip of the capillary and the electrode surface, cutting the other end of the metal wire to form the electrode. A bump forming method for forming a convex portion on a surface, wherein a constriction having an inner diameter smaller than the inner diameter of the capillary hole is provided at a predetermined position of the capillary hole. 9. After crimping one end of a metal wire projecting from the tip of a capillary having a capillary hole between the tip of the capillary and the electrode surface, cutting the other end of the metal wire to form the electrode A bump forming method for forming a concave portion on a surface, wherein a concave portion having a diameter smaller than an outer diameter of the bump is provided at a tip portion of the capillary. 10. An end of a metal wire protruding from a tip end of a capillary having a capillary hole is pressed between the tip end of the capillary and the electrode surface, and the other end of the metal wire is cut off to form the electrode. In a bump forming method of forming a convex portion on the surface, pressing a shaped die having a concave portion of a predetermined shape formed on a bump formed on an electrode surface of the surface-mounted electronic component,
A method of forming a bump, wherein an upper portion of the bump is shaped into a convex portion having a predetermined shape. 11. An end of a metal wire projecting from a tip end of a capillary having a capillary hole is pressed between the tip end of the capillary and the electrode surface, and the other end of the metal wire is cut to form the electrode. A bump forming apparatus for forming a convex portion on a surface, wherein a cutter for cutting the other end of the metal wire is provided at a position corresponding to a tip of the capillary.