JP3351303B2 - Method of bonding electronic components with bumps - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for bonding electronic components with bumps, which bonds the bumps of the electronic component with bumps to electrodes of a work such as a substrate.

[0002]

2. Description of the Related Art As a method of mounting an electronic component with a bump such as a flip chip on a work such as a substrate, a method using a suction tool is known. In this method, a bump of an electronic component with a bump that is vacuum-sucked on the lower surface of a suction tool is pressed against an electrode of a work and bonded.
In this case, it is known to apply ultrasonic vibration to the suction tool in order to enhance the bonding effect.

[0003]

The surface of the bump is not a smooth spherical surface but a rough surface having irregularities. For this reason, there is a problem that a minute gap is generated between the bump and the electrode surface of the work to which the bump is bonded, and that the bonding property and the conductivity are easily reduced.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method of bonding electronic parts with bumps, which can firmly bond bumps having irregularities on the surface to electrodes of a work.

[0005]

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 held by a suction tool lands on an electrode of a work, and a large ultrasonic vibration is applied to the electronic component with a bump. By applying a small load while applying a force, the first step of cleaning the contact surface between the bump and the electrode by mechanical friction while smoothing, and then reducing the ultrasonic vibration applied to the electronic component with the bump and reducing the load. By increasing the size, the gap between the bump and the electrode is crushed to increase the contact area,
Bonding the bump to the electrode.

[0006]

According to the present invention having the above-described structure, after the contact surface between the bump and the electrode is smoothed while being cleaned by mechanical friction, the gap between the bump and the electrode is crushed to enlarge the contact area. The bump can be firmly bonded to the electrode.

Hereinafter, embodiments of the present invention will 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 bonding process diagram of the electronic component with bumps, and FIG. Partial enlarged view, FIG.
FIG. 4A is a graph showing the change over time in the load of the electronic component with bumps, FIG.
(B) is a time-dependent change diagram of the ultrasonic vibration force of the electronic component with bumps.

First, the overall structure of a crimping apparatus for an electronic component 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 its rod 5 is connected to the second lifting plate 3. The bonding head 10 is mounted on the second lifting plate 3. On the upper surface of the support frame 1, a Z-axis motor 6 is provided. The Z-axis motor 6 has a vertical feed screw 7
To rotate. The feed screw 7 is screwed into a nut 8 provided on the back surface of the first lifting plate 2. Therefore, when the Z-axis 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 lifting plate 3
Also move 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 one-axis table 43, and the tip of the lens barrel 44 is sucked and held on the lower surface of the suction tool 22 as shown by a chain line.
The position of the flip chip 30 and the substrate 32 is observed by the camera 42 in this state. Then, the relative displacement between the flip chip 30 and the substrate 32 is detected based on the observation result. The detected displacement is
The correction is performed by driving the table 35 to horizontally move the substrate 32 in the X direction or the Y direction, whereby the bumps 31 of the flip chip 30 and the electrodes 33 (FIG. 2) of 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 control signal via a recognition unit 53. Connected to the camera 42. Further, the cylinder 4 is connected to the main control unit 50 via a load control unit 54, and the protrusion output of the rod 5 of the cylinder 4, that is, the force of pressing the flip chip 30 against the substrate 32 by the crimping tool 22 is controlled. In the present embodiment, the cylinder 4
An air-pneumatic regulator for digitally controlling the air pressure by the main control unit 50 is used as the load control unit 54.

In FIG. 1, a bonding head 10 mainly includes a main body 11, and a crimping unit 12 is provided below the main body 11. The crimping unit 12 is mainly composed of a rod-shaped horn 21, and a suction tool 2 for vacuum-holding and holding the flip chip 30 at the center of the horn 21.
Two. The horn 21 is provided with a piezoelectric element 19 as ultrasonic vibration means. Piezoelectric element 19
Are driven by the ultrasonic transducer driving unit 55.

The bonding apparatus for an electronic component with bumps is configured as described above. Next, the overall operation will be described. In FIG. 1, the flip chip 30 is held on the lower surface of the suction tool 22, and the flip chip 30 is positioned above the substrate 32. Then, the lens barrel 44 is advanced, and the images of the flip chip 30 and the substrate 32 are obtained by the camera 42.
The image data is sent to the recognition unit 53. The recognizing unit 53 detects a relative displacement between the flip chip 30 and the substrate 32 from the image data and outputs it to the main control unit 50. The main control unit 50 sends a command to the table control unit 52 according to the detection result. The table 35 is driven and the substrate 32 is moved horizontally to correct the displacement.

Next, the Z-axis motor 6 is driven to lower the bonding head 10 and the bumps 31 of the flip chip 30.
Is landed on the electrode 33 of the substrate 32, and the cylinder 4 is driven to start applying a load (FIGS. 2A and 4A).
Timing t1). Next, the load by the cylinder 4 is gradually increased, and the bump 31 is gradually and strongly pressed against the electrode 33, and the ultrasonic vibration of the suction tool 22 is started (timing t2 in FIG. 4B).

As shown in FIG. 4, the load applied to the bump 31 by the pressing force of the cylinder 4 is gradually increased from t1 to t3. During that time (between t2 and t3), a strong ultrasonic vibration force F1 is applied to the bump 31. This t
1 to t3 is a first step. The contact surface between the bump 31 and the electrode 33 is mechanically rubbed by the ultrasonic vibration of the bump 31 in FIG. It is smoothed while being cleaned. FIG. 3A shows a state at the beginning of the first step. As shown, the surfaces of the bumps 31 and the electrodes 33 are rough and have irregularities. A gap G exists. In addition, the surface of the bump 31 or the electrode 33 is liable to be stained by an oxide film or the like. However, in the case of a gold bump or a gold electrode, no oxide film is formed. FIG. 2B shows the above-described first step.

In FIG. 4A, in the second step from t3 to t4, a large load is continuously applied, and the ultrasonic vibration force is reduced from F1 to F2. As a result, the gap G is crushed, and the contact area between the bump 31 and the electrode 33 is increased (FIG. 3B), and the joint between the two is fused or an alloy is formed (FIG. 2C). The hatched portion 34 is a fusion portion or an alloy portion. Next, at timing t4, the application of the load and the application of the ultrasonic vibration are stopped, and the bonding operation is completed.

[0017]

According to the present invention, the bumps can be firmly bonded to the electrodes on the substrate while cleaning the surfaces of the bumps and the electrodes and crushing the bumps and bumps on the surfaces of the bumps.

[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 bonding process diagram of the electronic component with bumps according to one embodiment of the present invention;

FIG. 3 is an enlarged view of a part of the electronic component with bumps during bonding of the bumps according to the embodiment of the present invention;

FIG. 4A is a diagram showing a change over time of a load of an electronic component with a bump according to an embodiment of the present invention; FIG. 4B is a diagram showing a change over time of an ultrasonic vibration force of an electronic component with a bump according to an embodiment of the present invention;

[Explanation of symbols]

 22 Suction tool 30 Flip chip 31 Bump 32 Substrate 33 Electrode G Clearance

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-115109 (JP, A) JP-A-9-153524 (JP, A) JP-A-9-270443 (JP, A) JP-A-10- 335373 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/60 H01L 21/607

Claims (1)

(57) [Claims] A bump of an electronic component with a bump held by a suction tool is landed on an electrode of a work, and a small load is applied to the electronic component with a bump while applying a large ultrasonic vibration to the electronic component. The first step of smoothing the contact surface while cleaning it by mechanical friction, and then reducing the ultrasonic vibration applied to the electronic component with bumps and increasing the load, thereby crushing the gap between the bump and the electrode to make contact. A second step of increasing the area and bonding the bump to the electrode.