JP2003100799A - Mounting method of work with bump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mounting method of a work with bumps whereby the work with bumps can be firmly mounted on a board with a good workability. SOLUTION: After applying a bond 4 to a board 1, a work 6 with bumps which is held by a pressing tool 8 is mounted on the board 1, and ultrasonic vibrations are applied to it while it is applied with pressure. Then, the bump 7 bites into the solder 3 on an electrode 2, and is temporarily bonded metallically in the solder 3. Next, the board 1 is transported to a heating furnace and is heated. When the bond 4 is hardened, the work 6 with bumps is firmly bonded on the board 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for mounting a bumped work such as a flip chip which is bonded to a substrate by a bond.

[0002]

2. Description of the Related Art When mounting a work with bumps such as a flip chip on a substrate, the bumps of the work with bumps are aligned with the electrodes of the substrate and the work with bumps is mounted on the substrate. The work with bumps is mounted on the substrate by injecting a bond into the substrate and curing the bond. The bond is injected to firmly bond and mount the bumped work on the substrate.

[0003]

However, in the above-mentioned conventional method, since the bond is injected between the work having bumps and the substrate after the work having bumps is mounted on the substrate, the injection work requires a considerable time. Productivity is not improved, and due to insufficient injection, voids are likely to occur between the work with bumps and the substrate, and this void reduces the bond strength of the bond or is cured by thermal expansion of air in the void due to heat cycle. When the bond is broken and a void is formed near the electrode on the substrate, the air corrodes the electrode.

Further, since the bumps are soldered to the electrodes by heating and melting and solidifying the solder portions on the electrodes of the substrate, it takes a considerable time for soldering and the productivity is not improved. It was

Accordingly, it is an object of the present invention to provide a mounting method for a bumped work which can be mounted on a substrate firmly with good workability.

[0006]

A method of mounting a work with bumps according to the present invention comprises a step of applying a bond on the upper surface of a substrate and a step of landing the bumps of the work with bumps on a solder portion on an electrode of the substrate, A step of making the lower end of the bump into the solder part by applying vibration and temporarily adhering;
Curing the bond by heating to bond the work with bumps to the substrate.

Further, the method of mounting a work with bumps according to the present invention comprises a step of applying a bond on the upper surface of the substrate, and the bumps of the work with bumps are landed on the electrodes of the substrate and high-frequency vibration is applied to the bumps to form electrodes. And a step of permanently bonding the work with bumps to the substrate by hardening the bond by heating.

Also preferably, the top surface of the substrate is plasma etched prior to applying the bond to the top surface of the substrate.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention having the above-described structure, since the bond is applied to the substrate before mounting the work with bumps on the substrate, it is possible to realize a highly reliable mounting unlike the conventional method. Become. Also, since the bumps are temporarily bonded to the solder parts and electrodes by high frequency vibration, there is no need to heat and solidify the solder parts on the electrodes as in the conventional method, which shortens the takt time and improves productivity. You can

Further, prior to applying the bond to the upper surface of the substrate, the upper surface of the substrate is plasma-etched to activate the surface of the substrate, and the adhesive force of the bond to the substrate is greatly increased. The work can be mounted on the board firmly.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a process diagram of a substrate pretreatment according to an embodiment of the present invention, and FIG. 2 is a process diagram of mounting the work with bumps.

In FIG. 1, an electrode 2 is formed on the upper surface of the substrate 1. Solder portions 3 are formed on the electrodes 2. The solder portion 3 is formed as a precoat portion by a plating method, a leveler method, or the like. The substrate 1 is housed in a plasma processing chamber, and the plasma ions e are made to collide with the upper surface of the substrate to etch and activate the upper surface. When the pretreatment of the substrate 1 is completed as described above, the work with bumps is mounted on the substrate 1. Next, a method of mounting a work with bumps will be described with reference to FIG.

2A, 2B, and 2C show a method of mounting a bumped work in the order of steps. First, FIG.
As shown in (a), the bond 4 is applied to the upper surface of the substrate 1 by the bond applicator 5. This bond 4 is a thermosetting resin, and preferably a filler is mixed therein.

Next, as shown in FIG. 2B, the work 6 with bumps is mounted on the substrate 1. Bumps 7 are provided on the lower surface of the work 6 with bumps. The work 6 with bumps is vacuum-sucked and held on the lower surface of the crimping tool 8, and the bumps 7 are embedded in the bonds 4 to land on the solder portions 3 and mounted on the substrate 1. And work 6 with bump
Is pressed against the substrate 1 by the crimping tool 8 (arrow A), and the lower end of the bump 7 is fitted into the solder part 3 by the pressing force. The solder portion 3 is made of a soft alloy such as lead and tin, and the bump 7 is made of a conductive metal such as gold having good adhesiveness to the solder portion 3.

When the bumps 7 are pressed into the solder portion 3 to be embedded therein, high-frequency vibration is applied to the crimping tool 8 to ultrasonically vibrate the crimping tool 8 in the lateral direction (arrow B). Then, the metal-to-metal bonding progresses at the bonding portion between the bump 7 and the solder portion 3, and the bump 7 is bonded to the solder portion 3. This adhesive force is relatively small, and therefore this adhesive is called temporary adhesive in the present invention. When the work 6 with bumps is pressed against the substrate 1 while being ultrasonically vibrated in this way, the bond 4 also vibrates due to this ultrasonic vibration, and the bond 4 sufficiently wraps around the entire lower surface of the work 6 with bumps. Bubbles are also expelled.

Next, if the substrate 1 on which the bumped work 6 is mounted is sent to a heating furnace and the bond 4 is heated and cured,
The bumped work 6 is firmly bonded to the substrate 1 and the mounting is completed (FIG. 2C). In this case, since the surface of the substrate 1 has been activated by plasma etching in the pretreatment, the bond 4 firmly adheres to the substrate 1.

FIG. 3 is a mounting process diagram of a work with bumps according to another embodiment of the present invention. In FIG. 3 (a),
The bond applicator 5 applies the bond 4 to the upper surface of the substrate 1. No solder portion is formed on the electrode 2 of the substrate 1. The electrode 2 is preferably made of the same material as that of the bump 7 or gold-plated on the surface because it is easy to obtain metal-to-metal bonding. The substrate 1 is also preferably plasma-etched by the pretreatment shown in FIG. 1 to activate the surface of the substrate 1 and clean the surface of the electrode 2.

Next, the work 6 with bumps is vacuum-sucked and held by the pressure bonding tool 8, and the bumps (gold bumps) 7 are bonded.
The electrode 2 and land it on the electrode 2 (FIG. 3B), while pressing the bumped work 6 against the substrate 1 (arrow A),
Ultrasonic vibration is applied (arrow B). Then, the lower surface of the bump 7 is rubbed against the electrode 2 and becomes slightly flat, and the bump 7 is temporarily bonded to the electrode 2 by intermetallic bonding (see FIG. 3).
(C)). In this case, since the oxide film or the organic substance on the surface of the electrode 2 is removed by plasma cleaning the electrode 2 by the above-mentioned pretreatment, the bump 7 is more firmly adhered to the electrode 2. When the work 6 with bumps is pressed against the substrate 1 while being ultrasonically vibrated in this way, the bond 4 also vibrates due to this ultrasonic vibration, and the bond 4 fully wraps around the lower surface and front face of the work 6 with bumps. Bubbles are also expelled.

Next, if the substrate 1 on which the bumped work 6 is mounted is sent to a heating furnace and the bond 4 is heated and cured,
The bumped work 6 is firmly bonded to the substrate 1 and the mounting is completed (FIG. 3D).

[0020]

According to the present invention, since the bond is applied to the substrate before mounting the work with bumps on the substrate, it is possible to realize highly reliable mounting unlike the conventional method. Also, since the bumps are temporarily bonded to the solder parts and electrodes by high frequency vibration, there is no need to heat and solidify the solder parts on the electrodes as in the conventional method, which shortens the takt time and improves productivity. You can

Further, prior to applying the bond to the upper surface of the substrate, the upper surface of the substrate is plasma-etched to activate the surface of the substrate, and the adhesive force of the bond to the substrate is greatly increased. The work can be mounted on the board firmly. Also, the oxide film on the electrode surface can be removed by plasma etching, and the bumps can be more firmly adhered.

[Brief description of drawings]

FIG. 1 is a diagram showing a substrate pretreatment process according to an embodiment of the present invention.

FIG. 2 is a mounting process diagram of a work with bumps according to an embodiment of the present invention.

FIG. 3 is a mounting process diagram of a work with bumps according to another embodiment of the present invention.

[Explanation of symbols]

1 substrate 2 electrodes 3 Solder part 4 bond 6 Work with bump 7 bumps 8 Crimping tool

Claims (3)

[Claims] 1. A step of applying a bond to an upper surface of a substrate, and a bump of a work with bumps is landed on a solder portion on an electrode of the substrate, and high frequency vibration is applied to the lower end portion of the bump to the solder portion. A mounting method of a work with bumps, comprising: a step of making the bond work and temporarily adhering it; and a step of hardening the bond by heating to bond the work with bumps to the substrate. 2. A step of applying a bond to the upper surface of a substrate, and landing a bump of a work with bumps on an electrode of the substrate,
Mounting of a bumped work characterized by including a step of temporarily bonding the bump to the electrode by applying high-frequency vibration, and a step of hardening the bond by heating to bond the work with the bump to the substrate Method. 3. The method for mounting a work with bumps according to claim 1, wherein the upper surface of the substrate is plasma-etched prior to applying the bond to the upper surface of the substrate.