JPH11265913A - Bonding method for electronic component with bump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bonding method for electronic component with bump capable of stably performing bonding improved in the strength of bonding. SOLUTION: Concerning the bonding method for pressing the bump of an electronic component with bump through a bonding tool to the electrode of a substrate and bonding the bump to the electrode of the substrate by applying vibrations, a first pressing load F1 capable of generating plastic deformation and a second pressing load F2 as a proper bonding load for bonding the bump are set to the bump. At the time of bonding operation, the electronic component is first pressed with the first pressing load F1 and next pressed with the second pressing load F2, and vibrations are applied to the electronic component with bump. Thus, even when there is a difference in the heights of substrates or dispersion in the heights of bumps, bonding improved in the strength of bonding can be performed while making uniform the state of abutting the bump and the electrode of the substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for bonding a bumped electronic component to a substrate and bonding the bumped electronic component to a substrate.

[0002]

2. Description of the Related Art As a method for mounting electronic components with bumps such as flip chips, a method using ultrasonic pressure welding is known. According to this method, a bump of an electronic component with a bump is pressed against an electrode formed on a substrate, and ultrasonic vibration is applied to the electronic component with a bump so that a bonding surface between the bump and the substrate is rubbed with each other to perform bonding. .

[0003]

By the way, in order to bond the bump and the electrode well by this ultrasonic pressure welding, the bump and the electrode of the substrate are in contact under appropriate conditions required for the bonding. In the case of a bumped electronic component having a large number of bumps, it is necessary to uniformly contact all of these bumps with the electrodes. However, the height of the bump formed on the electronic component is not always uniform due to an error in the manufacturing process and varies within a certain range. Also, the substrate on which the electronic component with bumps is mounted may not be a perfect plane, but may have undulation and a partial height difference.

For this reason, when the electronic component with bumps is mounted on the substrate at the time of bonding, the contact surface between the bumps and the electrode surface of the substrate is not necessarily in a state in which all the bumps are in uniform contact, but is partially formed. In some cases, the bumps are not in contact with the electrodes, that is, in a so-called one-sided state.

[0005] When the ultrasonic vibration is applied by starting the bonding operation in this state, the ultrasonic vibration concentrates on some of the bumps in good contact state, or partially acts between the bump and the electrode. Since there is a gap, rattling occurs on the contact surface between the bonding tool and the electronic component. As a result, normal bonding is not performed, and the bonding strength is reduced.

Accordingly, an object of the present invention is to provide a method of bonding electronic components with bumps, which can stably perform bonding with excellent bonding strength.

[0007]

According to the method of bonding an electronic component with a bump of the present invention, a bump of the electronic component with a bump is pressed against an electrode of a substrate by a bonding tool and vibration is applied to the electronic component with a bump. And bonding the bump to an electrode of a substrate by bonding the bump to an electrode of a substrate, wherein the first pressing load is large enough to cause plastic deformation of the bump, and is lower than the first pressing load. A second load, which is an appropriate bonding load for bonding the bump to the electrode.
During the bonding operation, first, the electronic component with bumps is pressed against the electrode of the substrate by the first pressing load, and then the electronic component with bumps is pressed by the second pressing load. The vibration was applied to.

According to the present invention, during the bonding operation,
After the bump is pressed with a first pressing load of a size that causes plastic deformation, the bump is pressed with an appropriate bonding load lower than the first pressing load, and vibration is applied to the bump to form an electrode between the bump and the substrate. And the bonding state excellent in bonding strength can be performed.

[0009]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a front view of a bonding apparatus for an electronic component with bumps according to an embodiment of the present invention. FIG. 2 is a perspective view of a bonding tool for the electronic component with bumps.
3A is a front view of a bonding tool for the electronic component with bumps, FIG. 3B is a plan view of a bonding tool for the electronic component with bumps, and FIGS. FIG. 5A is a cross-sectional view of a substrate, and FIG. 5A is a graph showing a change in a pressing load during bonding of the electronic component with bumps;
(B) is a timing chart of the application of ultrasonic vibration during bonding of the electronic component with bumps.

First, the overall structure of a bonding apparatus for electronic components with bumps will be described with reference to FIG. Reference numeral 1 denotes a support frame, on the front surface of which a first lifting plate 2 and a second lifting plate 3 are provided so as to be able to move up and down. A cylinder 4 is mounted on the first lifting plate 2, and the rod 5 is attached to the second lifting plate 3.
Is joined to. The bonding head 10 is mounted on the second lifting plate 3. Z on the upper surface of the support frame 1
A shaft motor 6 is provided. The Z-axis motor 6 rotates a vertical feed screw 7. The feed screw 7 is screwed into a nut 8 provided on the back surface of the first lifting plate 2. Therefore Z
When the shaft motor 6 is driven and the feed screw 7 is rotated, the nut 8 moves up and down along the feed screw 7, and the first lifting plate 2 and the second
The lifting plate 3 also moves up and down.

In FIG. 1, a substrate 32 is a substrate holder 34.
The substrate holder 34 is placed on a table 35. The table 35 is a movable table, and moves the substrate 32 horizontally in the X direction and the Y direction.
2 is positioned at a predetermined position.

Reference numeral 42 denotes a camera, which is a uniaxial table 43
It is attached to. Reference numeral 44 denotes a lens barrel extending forward from the camera 42. The camera 42 is moved forward along the uniaxial table 43, and the tip of the lens barrel 44 is positioned between the electronic component 30 with bumps and the substrate 32 held by being sucked and held on the lower surface of the bonding tool 14, as indicated by a chain line, In this state, the positions of the electronic component with bumps 30 and the substrate 32 are observed with the camera 42. According to the observation result, the electronic component 3 with bumps
A relative displacement between 0 and the substrate 32 is detected. The detected positional deviation is corrected by driving the table 35 to horizontally move the substrate 32 in the X direction or the Y direction, whereby the electronic component 30 with bumps and the substrate 32 are aligned.

In FIG. 1, reference numeral 50 denotes a main control unit, which controls the Z-axis motor 6 via a motor drive unit 51, controls the table 35 via a table control unit 52, and receives a signal via a recognition unit 53. Connected to the camera 42. The cylinder 4 is connected to the main control unit 50 via a load control unit 54, and the projection load of the rod 5 of the cylinder 4, that is, the pressing load for pressing the bumped electronic component 30 against the substrate 32 by the bonding tool 14 is controlled. .

A holder 12 is connected to the lower end of the main body 11 of the bonding head 10. A block 13 is mounted on the holder 12, and a bonding tool 14 is fixed to the block 13. Hereinafter, the block 13 and the bonding tool 14 will be described with reference to FIGS.

As shown in FIG. 2, the bonding tool 1
The horn 15 is an elongated rod-shaped body, and ribs 15 are provided on four sides of the horn 15 at equal distances from the center of the horn 15.
a is provided integrally with the horn 15. The bonding tool 14 is fixed to the lower surface of the block 13 by a rib 15a.

On the lower surface of the center of the bonding tool 14, there is provided a holding portion 15e which projects downward and holds the electronic component 30 with a bump by vacuum suction. The lower surface of the holding portion 15e has a suction surface for sucking the electronic component. 15f. One end of an inner hole 16 for vacuum suction provided in the horn 15 is opened in the suction surface 15f to form a suction hole 16a.
The other end of the inner hole 16 opens at the position of the rib 15a on the upper surface of the horn 15 to form a suction hole 16b.

The protrusion 13 provided on the side surface of the block 13
4A is provided with a tube portion 18 projecting downward.
The suction pad 19 attached to the lower end of the tube 18 is in contact with the position of the suction hole 16b on the upper surface of the horn 15, as shown in FIG. Therefore, the projection 13a is connected to the projection 13a.
Tube 20 communicating with the tube portion 18 by the inner hole 13b of the tube 20
Then, by driving the suction device 21 to suck air, the suction hole 1 opened on the suction surface 15 e through the inner hole 16.
6a (FIGS. 3 (a) and 3 (b)), it is possible to hold the electronic component 30 with bumps by vacuum suction on the suction surface 15f.

A vibrator 17 as a vibration applying means is mounted on a side end surface of the horn 15. By driving the vibrator 17, longitudinal vibration is applied to the horn 15, and the holding portion 15e vibrates in the horizontal direction (the direction of the arrow a shown in FIG. 3A). As shown in FIG. 3B, the horn 15 has a shape in which the width is gradually reduced in the direction from the both end portions 15b to the center portion 15d via the tapered portion 15c, and thereby the horn 15 is held by the vibrator 17. The amplitude of the ultrasonic vibration is amplified in the path transmitted to the portion 15e, and a vibration having an amplitude equal to or greater than the amplitude oscillated by the vibrator 17 is transmitted to the holding portion 15e.

The bonding device for an electronic component with bumps is configured as described above, and the operation will be described next.
In FIG. 1, the electronic component 30 with bumps is held on the suction surface 15 e of the bonding tool 14 by vacuum suction.
2 above. Then, the lens barrel 44 is advanced, and the images of the electronic component 30 with bumps and the substrate 32 are obtained by the camera 42, and the image data is sent to the recognition unit 53. Main control unit 5
0 indicates the electronic component 30 with bumps and the substrate 3 based on the image data.
2 is detected, the table 35 is driven in accordance with the detection result, and the substrate 32 is horizontally moved to perform position correction.

Next, the Z-axis motor 6 is driven to lower the bonding head 10 and press the bumps of the electronic component 30 with bumps against the electrodes 33 of the substrate 32. At this time, FIG.
As shown in (2), there is a height difference on the upper surface of the substrate 32, and a gap c may be partially generated between the bump 31 and the electrode 33. Therefore, in order to eliminate such a difference in height between the upper surface of the substrate 32 and the gap c between the bumps 31 and the electrodes 33 and non-uniform contact states caused by variations in the height of the bumps 31, a load control unit is required during the bonding operation. The pressing load is controlled by 54.

The control of the pressing load will be described with reference to FIG. First, at the start of the bonding operation, the bonding tool 14 is lowered. As a result, FIG.
As shown in (a), the bump 31 of the electronic component 30 with a bump is provided.
The pressing load increases from timing t <b> 1 at which the substrate abuts on the electrode 33 of the substrate 32. When the pressing load reaches the first pressing load F1, which is a load capable of causing plastic deformation of the bump 31, the pressed state is maintained for a predetermined time by this load.

As a result, the electrodes 3 of the bumps 31 have already been formed.
3 is sequentially plastically deformed by the pressing load, and as a result, the unevenness of the height of the bumps 31 and the one-sided contact state caused by the undulation of the substrate 32 are eliminated, and FIG.
As a result, all the bumps 31 come into contact with the electrodes 33 as shown in FIG. The first pressing load F1 may be set by calculation based on the size and quantity of the bumps 31 of the target electronic component 30 with bumps, or may be set based on the result of actual bonding trial. good.

Next, as shown in FIG. 5A, at timing t2, the pressing load is switched from the first pressing load F1 to the second pressing load F2. The second pressing load is set to be lower than the first pressing load, and is set as an optimum load for bonding by ultrasonic vibration. At the same time as the timing t2 or at the timing t
After step 2, the vibrator 17 is driven to apply ultrasonic vibration to the bumped electronic component 30 by the bonding tool 14. Thereby, in a state where all the bumps 31 and the electrodes 33 are uniformly in contact with each other, ultrasonic vibration is applied to the contact surface, and uniform bonding without deviation can be performed.

As described above, in the present embodiment, the bumped electronic component 30 is pressed with a high load in order to eliminate the one-sided contact state of the bump 31 and the electrode 33 which causes the bonding failure. Is switched. This eliminates the one-sided contact state and performs good bonding excellent in bonding strength without causing new bonding defects such as crushing of the bump 31 and reduction in bonding strength due to bonding with an excessively high load. be able to.

[0025]

According to the present invention, during the bonding operation, the bump is pressed by the first pressing load that can cause plastic deformation of the bump to eliminate the contact between the bump and the electrode of the substrate. Vibration is applied while pressing with an appropriate bonding load that is lower than the pressing load, so new bonding defects such as crushed bumps and reduced bonding strength due to bonding with an excessively high load are caused. In addition, it is possible to eliminate the one-sided contact state and perform good bonding with excellent bonding strength.

[Brief description of the drawings]

FIG. 1 is a front view of a bonding apparatus for an electronic component with bumps according to an embodiment of the present invention.

FIG. 2 is a perspective view of a bonding tool for an electronic component with bumps according to an embodiment of the present invention.

3A is a front view of a bonding tool for an electronic component with bumps according to one embodiment of the present invention; FIG. 3B is a plan view of a bonding tool for an electronic component with bumps according to one embodiment of the present invention;

4A is a cross-sectional view of an electronic component with a bump and a substrate according to an embodiment of the present invention. FIG. 4B is a cross-sectional view of an electronic component with a bump and a substrate according to an embodiment of the present invention.

FIG. 5A is a graph showing a change in a pressing load at the time of bonding of the electronic component with bumps according to the embodiment of the present invention; Timing chart for applying sound wave vibration

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Bonding head 13 Block 14 Bonding tool 15e Holding part 16a Suction hole 17 Vibrator 30 Electronic component with bump 31 Bump 32 Substrate 33 Electrode 50 Main control part 54 Load control part

Claims (1)

[Claims] An electronic component with a bump, wherein the bump of the electronic component with a bump is pressed against an electrode of a substrate by a bonding tool and vibration is applied to the electronic component with a bump to bond the bump to the electrode of the substrate. A bonding method, comprising: a first pressing load large enough to cause plastic deformation of the bump; and a proper bonding for bonding the bump to an electrode with a lower load than the first pressing load. A second pressing load, which is a load, is set, and at the time of the bonding operation, first, the electronic component with bumps is pressed against the electrode of the substrate by the first pressing load, and then pressed by the second pressing load. A method of bonding electronic components with bumps, wherein vibration is applied to the electronic components with bumps.