JP2000164630A - Method and substrate for mounting electronic components - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic component mounting method by which electronic components can be mounted on a substrate, without requiring sealing material by bonding the components to substrate electrodes using Au and electronic component pads to the substrate electrodes by using an intermetallic compound, so as to reduce the connection resistance values between the components and pads and the electrodes and an electronic component mounting substrate manufactured by the method. SOLUTION: After Au bumps 3 are formed on the pads 2 of electronic components, in such a way that the heights of the bumps 3 are made uniform, the bumps 3 are aligned with substrate electrodes 5, the components are stuck to a bonding tool through vacuum and mounted on a substrate 4 while a temperature, load, and ultrasonic waves are applied. Since an intermetallic compound is formed between the metallic pads 2 of the components or the metallic electrodes of the substrate 4 and the Au bumps 3, when the pads 2 are connected to the electrodes through the Au bumps 3, the connection resistance between the parts and substrate 4 is reduced and an electronic component mounting method which requires no sealing material and an electronic component mounting substrate manufactured by the method can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of mounting an electronic component and a method of bonding a metal pad of an electronic component including a functional device such as an IC or a SAW filter or an LED to a metal electrode of a substrate with a bump interposed therebetween. The present invention relates to an electronic component mounting board manufactured by a component mounting method.

[0002]

2. Description of the Related Art In recent years, the production of ICs (semiconductors), which are electronic components, continues to increase, and various mounting methods have been proposed. Among them, flip chip mounting method is downsizing of products,
It is indispensable for weight reduction. Conventionally, the flip chip mounting method includes a method using an Ag paste as a bonding material, a method using solder, and a method using metal fine particles. Hereinafter, the conventional I described above will be described with reference to the drawings.
A method of mounting C will be described. FIG. 4A shows the conventional I
3 shows a mounting state of an IC formed by implementing the mounting method C. In the figure, 1 is an IC, 2 is an I of IC1.
The C pad, 3 are Au bumps on the IC pad 2, 4 is the substrate, 5 is the substrate electrode of the substrate 4, 7 is the sealing material, 8 is the Ag paste, 9 is the solder, and 10 is the fine metal particles. The conventional IC mounting method is as follows. First,
As shown in FIG. 4 (b), A is placed on IC pad 2 of IC1.
After forming the u bump 3, the Ag paste 8, the solder 9, and the metal fine particles 10 are supplied as the bonding material, and the substrate electrode 5 on the substrate 4 is supplied.
After mounting, heating is performed to complete the bonding. Finally, FIG.
As shown in (c), the sealing material 7 is injected into the junction between the IC 1 and the substrate 4 and the temperature is applied to cure the sealing material 7. As a result, the mounting state of the IC 1 as shown in FIG.

[0003]

However, in the above configuration, since the bonding material 7 exists between the Au bump 3 and the substrate electrode 5, the connection resistance is high, and the bonding materials 8, 9 , 10 and the sealing material 7 have a problem that the curing time is long. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems, and to connect an electronic component and a substrate electrode using Au and an electronic component pad and a substrate electrode using an intermetallic compound to form a connection resistance. It is an object of the present invention to provide an electronic component mounting method which has a low value and does not require a sealing material, and an electronic component mounting board manufactured by the electronic component mounting method.

[0004]

In order to achieve the above object, the present invention is configured as follows. According to the first aspect of the present invention, the metal pad of the electronic component and the metal electrode of the substrate are joined with the Au bump interposed therebetween, so that one of the metal pad and the metal electrode and the Au bump are interposed. Forming an intermetallic compound, and electrically bonding the metal pad of the electronic component and the metal electrode of the substrate via the Au bump to mount the electronic component and the substrate. An electronic component mounting method is provided. According to a second aspect of the present invention, there is provided the electronic component mounting method according to the first aspect, wherein the Au bump is formed on the pad of the electronic component. According to a third aspect of the present invention, there is provided the electronic component mounting method according to the first aspect, wherein the Au bump is formed on the substrate side. According to a fourth aspect of the present invention, there is provided the electronic component mounting method according to any one of the first to third aspects, wherein leveling is performed before joining in order to make the heights of the Au bumps uniform. According to a fifth aspect of the present invention, there is provided the electronic component mounting method according to any one of the first to fourth aspects, wherein the electrode material of the metal pad or the metal electrode is Au or Al. According to the sixth aspect of the present invention, when the intermetallic compound is formed, the bonding portion between the pad or the electrode and the Au bump is vibrated using ultrasonic waves to join the two with frictional energy, An electronic component mounting method according to any one of the first to fourth aspects, wherein the electronic component forms an intermetallic compound. According to the seventh aspect of the present invention, the electronic component according to any one of the first to sixth aspects, wherein only the substrate is heated at the time of bonding one of the metal pad and the metal electrode to the Au bump. Provide a way. According to an eighth aspect of the present invention, there is provided an electronic component mounting board without a sealing material, wherein the electronic component is mounted on the board by the electronic component mounting method according to any one of the first to eighth aspects. . According to a ninth aspect of the present invention, the electronic component includes an IC or a SAW filter or an LED.
The electronic component mounting method according to any one of the first to ninth aspects for mounting a functional device such as the above.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an electronic component mounting method according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side view of an electronic component mounting board manufactured by implementing an electronic component mounting method according to the following embodiment of the present invention. In FIG. 1, 1 is an IC as an example of an electronic component, 2 is a metal IC pad of the IC 1,
3 is an Au bump, 4 is a substrate, and 5 is a metal substrate electrode of the substrate 4.

The operation of the IC mounting method according to the first embodiment will be described below with reference to FIG. First, as a first step, as shown in FIG. 2A, an Au bump 3 is formed on a metal IC pad 2 and the bump heights are aligned by leveling.
(Positioning) with the metal substrate electrode 5 described above. This alignment is necessary regardless of the leveling. At the time of alignment, the bonding tool 6
IC1 is sucked.

Next, as a second step, as shown in FIG. 2B, the IC 1 formed in the first step is sucked to the bonding tool 6 by suction of the vacuum suction device 19, and the metal pad 1 of the IC 1 is drawn. And the metal electrode 5 of the substrate 4
The IC 1 is pressed against the substrate 4 by the bonding tool 6 so that the bonding is performed with the u bumps 3 interposed therebetween. At this time,
Heating device 20, pressing device 2 from the bonding tool 6 side
1. A temperature, a load, and an ultrasonic wave are applied to the substrate 4 by the ultrasonic vibration device 22. In this way, by joining the metal pad 1 of the IC 1 and the metal electrode 5 of the substrate 4 with the Au bump 3 interposed therebetween, an intermetallic compound is formed between the metal electrode 5 and the Au bump 3. The metal pad 1 of the IC 1 and the metal electrode 5 of the substrate 4 are electrically connected via the Au bump 3, and the IC 1 is connected to the substrate 4.
To be implemented. By using ultrasonic waves when forming the intermetallic compound, the electrode 5 and the A
By vibrating the joint with the u-bump 3 and joining the two with frictional energy, the intermetallic compound is formed. At this time, only the substrate 4 may be heated by the heating device 20 when the IC is mounted.

In the first embodiment, one condition for forming an intermetallic compound is, for example, 150 ° C. or more, 50 (g / bump) or more, and the ultrasonic wave amplitude is 0.5 μm or more. Is preferred.

Next, the operation of the electronic component mounting method according to the second embodiment of the present invention will be described with reference to FIG. First, as a first step, as shown in FIG. 3A, an Au bump 3 is formed on a metal substrate electrode 5 of a substrate 4.
After the bump height is adjusted by leveling,
The Au bump 3 is aligned (positioned) with the metal IC pad 2 of the IC 1 as an example of the electronic component. This alignment is necessary regardless of the leveling. At the time of alignment, the IC 1 is sucked by the bonding tool 6. Next, as a second step, FIG.
As shown in (b), the IC 1 formed in the first step
The bonding tool 6 is sucked by the vacuum suction device 19.
The IC 1 is pressed against the substrate 4 by the bonding tool 6 so that the metal pad 1 of the IC 1 and the metal electrode 5 of the substrate 4 are joined together with the Au bump 3 interposed therebetween.
At this time, the heating device 20 from the bonding tool 6 side,
The pressure, the load,
Ultrasonic waves are applied to the substrate 4. Thus, the IC
The first metal pad 1 and the metal electrode 5 of the substrate 4 are joined together with the Au bump 3 interposed therebetween to form an intermetallic compound between the first metal pad 1 of the IC 1 and the Au bump 3, thereby forming the first metal pad 1. The metal pad 1 is electrically connected to the metal electrode 5 of the substrate 4 via the Au bump 3, and the IC 1 is mounted on the substrate 4. By using ultrasonic waves when forming the intermetallic compound in this way, the junction between the IC pad 2 and the Au bump 3 is vibrated to join them with frictional energy to form the intermetallic compound. I do. At this time, only the substrate 4 may be heated by the heating device 20 when the IC is mounted.

In the second embodiment, one condition for forming an intermetallic compound is, for example, 150 ° C. or more, 50 (g / bump) or more, and the ultrasonic wave amplitude is 0.5 μm or more. It is preferable that

According to each of the above embodiments, the metal pad 2 of the IC 1 and the metal electrode 5 of the substrate 4 are joined with the Au bump 3 interposed therebetween, and the metal pad 2 or the metal electrode 5 and the Au bump 3 are interposed. The connection resistance is reduced by joining with an intermetallic compound (in other words, a state in which different metals are mixed at a certain ratio) (for example, the connection resistance can be reduced by about 2 to 4 mΩ in a four-terminal measurement). If the connection resistance value is, for example, 20 mΩ, the resistance is 16 mΩ.) By improving the bonding strength, the bonding reliability can be obtained without sealing the gap between the IC 1 and the substrate 4 with an insulating resin. be able to. Further, by using Au or Al as an electrode material of the metal pad 2 of the IC 1 and the metal electrode 5 of the substrate 4, it is possible to easily join at a low temperature of 200 ° C. or less. The intermetallic compound is also formed when a bump is previously formed on a pad or a substrate electrode before joining.

In the first and second embodiments, when bumps are formed on an IC, the number of times of bonding is two based on the IC pad. Also, when bumps are formed on a substrate, the number of times of bonding is 1 based on IC pads.
Times. Therefore, in consideration of damage to the IC, it is better to perform bonding with as little stress as possible. Therefore, forming bumps on the substrate side provides higher connection reliability and a wider range of bonding conditions. Note that the present invention is not limited to the above embodiment, and can be implemented in other various aspects. For example, instead of an IC as an example of an electronic component,
Another example of electronic components is SAW (Surface Acoustic Wav).
edevice) It can also be applied to functional devices such as filters or LEDs.

[0013]

As described above, the metal pad of the electronic component and the metal electrode of the substrate are joined with the Au bump interposed therebetween, and an intermetallic compound is formed between the metal pad or the metal electrode and the Au bump. In addition, it is possible to realize an electronic component mounting method and an electronic component mounting substrate manufactured by the method, in which a connection resistance value between the electronic component and the substrate is low and a sealing material is not required.

[Brief description of the drawings]

FIG. 1 is a side view of an electronic component mounting board in a state where an IC as an example of an electronic component is mounted on a board by performing an electronic component mounting method according to the first or second embodiment of the present invention. is there.

FIG. 2A is a side view showing a state in which a bump is formed on an IC in a first step of a method of mounting an electronic component according to a first embodiment of the present invention, and the bump is aligned with a substrate electrode. FIG. 2B is a side view showing an IC mounted state in which the IC and the substrate are joined by an Au electrode in a second step of the electronic component mounting method of the first embodiment.

FIG. 3A is a side view showing a state in which a bump is formed on a substrate in a first step of an electronic component mounting method according to a second embodiment of the present invention, and the bump is aligned with an IC pad. FIG. 7B is a side view showing an IC mounting state in which the IC and the substrate are joined by Au electrodes in a second step of the electronic component mounting method of the second embodiment.

4A is a side view showing a state in which a conventional IC and a substrate are joined with an Ag paste, FIG. 4B is a side view showing a state in which the conventional IC and a board are joined with solder, and FIG. I
It is a side view which shows the state which joined C and the board | substrate with the metal fine particle.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... IC, 2 ... IC pad, 3 ... Au bump, 4 ... Substrate, 5 ... Board electrode, 6 ... Bonding tool, 7 ... Sealing material, 8 ... Ag paste, 9 ... Solder, 10 ... Metal fine particle,
19: vacuum suction device, 20: heating device, 21: pressurizing device, 22: ultrasonic vibration device.

Continued on the front page (72) Inventor Hiroshi Wada 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. ) 5F044 KK17 KK18 LL01 LL04 QQ02 QQ03

Claims (9)

[Claims] 1. A metal pad (1) of an electronic component (1) and a metal electrode (5) of a substrate (4) are joined together with an Au bump (3) interposed therebetween so that the metal pad (1) and the metal pad (1) are joined together. One of the metal electrodes (5) and the Au bump (3)
To form an intermetallic compound between the first and second electronic components (1)
Electrically connecting said metal pad (1) and said metal electrode (5) of said substrate (4) via said Au bump (3) to mount said electronic component and said substrate. Electronic component mounting method. 2. The method according to claim 1, wherein the Au bump is formed on the pad of the electronic component. 3. The method according to claim 1, wherein the Au bump is formed on the substrate. 4. In order to make the height of the Au bump uniform,
The method for mounting an electronic component according to claim 1, wherein leveling is performed before joining. 5. The electronic component mounting method according to claim 1, wherein an electrode material of said metal pad (2) or said metal electrode (5) is Au or Al. 6. A method of forming the intermetallic compound by vibrating a bonding portion between the pad or the electrode and the Au bump using ultrasonic waves when forming the intermetallic compound, and joining the two with frictional energy to form the intermetallic compound. The method for mounting an electronic component according to claim 1. 7. The electronic device according to claim 1, wherein only the substrate is heated when one of the metal pad (1) and the metal electrode (5) is bonded to the Au bump (3). Component mounting method. 8. An electronic component mounting board without a sealing material, wherein the electronic component is mounted on the board by the electronic component mounting method according to claim 1. 9. The electronic component may be an IC or a SAW.
The method for mounting an electronic component according to claim 1, wherein a functional device such as a filter or an LED is mounted.