JP2001102408A - Circuit board for mounting flip chip and method for mounting flip chip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit board for mounting and a mounting method for removing and reducing connection failures between the conductive electrode of the circuit board and the electrode pad of a semiconductor element due to the irreglarities of the surface of the circuit board at the time of connecting the conductive electrode of the circuit board and the electrode pad of the semiconductor element in flip chip mounting using conductive adhesive. SOLUTION: A plurality of conductive electrodes 2 are formed at the prescribed positions of the surface of a circuit board 1, and then the surfaces of the conductive electrodes are polished so that the surfaces of the plurality of conductive electrodes can be turned into the same plane, and while conductive adhesive 5 is adhered to the electrode pads of a semiconductor element to be jointed, the electrode pads are press-fit to the conductive electrodes 2 so that the electrode pads can be electrically connected with the conductive electrodes 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board used for flip-chip mounting for connecting a semiconductor element to a circuit board and a flip-chip mounting method using the circuit board. Provided are a circuit board and a mounting method that can be connected in a good state without variation in connection resistance with a conductor electrode of the board.

[0002]

2. Description of the Related Art In recent years, with the demand for miniaturization of electronic equipment, high-density mounting of circuit modules is desired. For this purpose, semiconductor elements mounted on semiconductor devices have been reduced in size from conventional plastic molded products to bare chips, and various companies have been developing various mounting methods. Among these, flip-chip mounting has attracted attention as a method of mounting bare chip semiconductor elements.

A circuit board for flip-chip mounting using a conventional circuit board and a mounting method will be described below with reference to FIG. A conductive adhesive 5 is transferred and attached to the bumps 4 formed on the electrode pads of the semiconductor element 3 to be joined,
While facing the circuit board 1 having the conductor electrodes 2 formed for flip-chip mounting, the chip head holding the semiconductor elements 3 is gradually lowered at a constant speed, and the conductor electrodes 2 and the bumps 4 are accurately aligned. While crimping,
Thereafter, a sealing resin was injected and cured, and flip-chip mounting was performed.

[0004]

However, in the conventional flip-chip mounting circuit board, the surface smoothness of the fired circuit board 1 has irregularities of about several tens to about 100 μm.
Irregularities of about several tens to 100 μm remained between the surfaces of the plurality of conductor electrodes 2 formed by screen printing or the like on the surface. When flip-chip mounting is performed on such a circuit board 1 using the conductive adhesive 5, even if the amount of the conductive adhesive 5 attached is constant,
At each connection between the conductor electrode 2 and the bump 4, there were variations in the connection resistance value such that some of the connections were not sufficiently bonded or some of the connections were unstable. . In addition, when there is a difference in the amount of the conductive adhesive 5 attached, a connection failure in manufacturing such as a connection failure such that the conductive adhesive 5 does not adhere to the conductor electrode 2 is reduced, and the connection yield in manufacturing is reduced. There was also a problem that.
When a mounted product having a variation in connection resistance as described above is used as a component of an electronic device, a malfunction of the electronic device may occur due to a high connection resistance of some of the electrode terminals. There was such a problem.

[0005]

In order to solve the above-mentioned problems, a flip-chip mounting circuit board according to the present invention comprises a plurality of conductor electrodes formed at predetermined positions on the surface of the circuit board.
The surface of the conductor electrode is polished so that the surfaces of the plurality of conductor electrodes are flush with each other, so that the connection between the electrode pad and the electrode conductor portion is stable and the connection resistance value is also low. And a semiconductor device having a high yield can be provided. Further, since a film such as an oxide or a deposit formed on the surface of the electrode can be removed by polishing, an increase in the resistance value due to the oxide or the deposit can be prevented, and a stable connection with a low resistance value can be realized.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, a plurality of conductor electrodes formed at predetermined positions on a surface of a circuit board are arranged so that the surfaces of the plurality of conductor electrodes are flush with each other. A circuit board for flip-chip mounting, characterized in that the surface of the conductor electrode is polished, and in flip-chip mounting using a conductive adhesive, a substrate in which the surface positions of the connection conductor electrodes are aligned with a mounting board By using as a, it becomes possible to provide a semiconductor device having a stable and high yield, and since a film such as an oxide or a deposit generated on the surface of the conductor electrode can be removed by polishing,
It is possible to prevent an increase in resistance value due to oxides and deposits, and to realize a stable connection with a low resistance value.

Next, the invention according to claim 2 of the present invention is:
2. The flip-chip mounting circuit board according to claim 1, wherein unevenness between the surfaces of the plurality of conductor electrodes is polished to 10 μm or less, and between the surfaces of the conductor electrodes formed on the circuit board. 3. By regulating the unevenness to 10 μm or less, a semiconductor device can be manufactured stably with a high yield.

Next, the invention according to claim 3 of the present invention provides:
After a film of carbon-based material is formed at a plurality of predetermined positions on a circuit board, the surface of the film is polished so that the surface of the film is flush with the surface of the film. A flip-chip mounting circuit board characterized in that a carbon film is formed as a conductor electrode for connecting a semiconductor element, and a conductive diamond-like carbon film is formed on each surface of the conductive layer. Thus, the increase in resistance value due to oxidation is eliminated.

Next, the invention described in claim 4 of the present invention is:
After a plurality of conductor electrodes are formed at predetermined positions on the surface of the circuit board, the surfaces of the plurality of conductor electrodes are polished so that the surfaces of the plurality of conductor electrodes are flush with each other. A flip-chip mounting method, wherein the electrode pad is pressed against the semiconductor electrode in a state where a conductive adhesive is adhered, and the electrode pad and the conductive electrode are electrically connected. By using a substrate having the same electrode position as the mounting substrate, it is possible to provide a semiconductor device having a stable and high yield and to provide oxides and deposits generated on the conductor electrode surface. Since the film can be removed by polishing, it is possible to prevent an increase in resistance value due to an oxide or a deposit, and to realize a stable connection with a low resistance value.

Next, the invention described in claim 5 of the present invention is:
The flip-chip mounting method according to claim 4, wherein the unevenness between the surfaces of the plurality of conductive electrodes is polished to 10 µm or less, and the unevenness on the surface of the conductive electrodes formed on the circuit board is set to 10 µm or less. By regulating, a semiconductor device can be manufactured stably with a high yield.

Next, the invention according to claim 6 of the present invention is as follows:
After forming a conductive layer with a carbon-based material paste at a plurality of predetermined positions on the surface of the circuit board, the surface of the conductive layer is polished so that the surfaces of the plurality of conductive layers are flush with each other, and the polished surface is polished. A conductive electrode is formed by forming a conductive diamond-like carbon film on the surface of the conductive layer, and the electrode pad is connected to the electrode pad while a conductive adhesive is attached to the electrode pad of the semiconductor element to be joined. A flip-chip mounting method characterized in that a semiconductor electrode is pressed into contact and an electrode pad and a conductive electrode are electrically connected. In flip-chip mounting using a conductive adhesive, an electrode of a connecting conductive electrode is provided. By using a substrate having a smooth surface on the surface as a mounting substrate, a semiconductor device having a stable and high yield can be provided. Further, since the surface of the conductor electrode is covered with the conductive diamond-like carbon film, it is possible to prevent the resistance value from increasing due to the covering of the oxide or the deposit.

(Embodiment 1) Hereinafter, claim 1 of the present invention will be described.
An embodiment of the invention described in claim 6 will be described with reference to FIG.

In FIG. 1, a circuit board 1 is composed of a ceramic substrate, and a plurality of conductor electrodes 2 formed of a silver-palladium conductor or the like are screen-printed at predetermined positions on the fired circuit board 1. Is formed. As described above, in the case of a normal ceramic circuit substrate, the surface smoothness of the fired substrate surface is unevenness of about several tens to 100 μm, so that the surface of the plurality of conductor electrodes 2 formed by screen printing on the substrate surface is reduced. At least several tens to 100 μm
There was a difference in elevation. Therefore, in the present invention, after the formation of the conductor electrodes 2, at least a part of the electrode surfaces of the conductor electrodes 2 in the semiconductor mounting region of the circuit board 1 is polished to make the heights of the electrode surfaces of the plurality of conductor electrodes 2 uniform. A structure having the same flat surface 6 is adopted. With such a configuration, the above-mentioned disadvantages are solved, and the bumps 4 formed on the electrode pads of the semiconductor element and the conductor electrodes 2 can be securely bonded.

The surface of the electrode conductor 2 is polished using a grinder having a smooth surface, and the unevenness between the polished surface of the plurality of electrode conductors 2 has a flatness of 10 μm or less. Obtained flat surface 6 is obtained. The grinding material of the grinder must be a hard substance that can withstand abrasion and a material that can be easily removed even if grinding flaws occur. Further, according to the configuration of the circuit board of the present invention, after the electrode conductor 2 is formed, a film such as an oxide or an adhering substance generated so as to cover the electrode surface of the electrode conductor 2 with the passage of time is entirely removed by polishing. Therefore, it is possible to prevent an increase in the resistance value due to oxides and deposits, and to realize a stable connection with a low resistance value.

(Embodiment 2) A method of manufacturing a circuit board 1 that more reliably solves the problem of preventing an increase in the resistance value due to the above-mentioned covering by an oxide or a deposit will be described with reference to FIG.

In FIG. 2, a plurality of conductive layers 7 at predetermined positions on the circuit board 1 are formed by forming a carbon film by screen printing using a carbon-based paste material.
It is formed by firing at about 0 ° C. to 800 ° C. Thereafter, the surface of the conductive layer 7 in the semiconductor element mounting region of the circuit board 1 is polished with a grinder having a smooth surface or the like to obtain a flat surface having a surface roughness of 10 μm or less. Finally, a thin conductive DLC (diamond-like carbon) of 0.1 μm or less is placed on the polished surface of the conductive layer 7.
The film 8 is formed by a method such as a sputtering method or a laser ablation method. DLC is a non-doped DLC having an amorphous structure of diamond.
There is a DLC doped with fluorine, nitrogen, and boron, but in this embodiment, any of them may be used. Thus, the circuit board 1 of the present invention having the conductor electrodes 2 in which the polished surface of the conductive layer 7 is not covered with the oxide film or the deposit is obtained.

The conductor electrodes 2 of the circuit board 1 and the bumps 4 of the semiconductor element 3 are connected to the circuit board 1 obtained by such a method while accurately aligning the conductive electrodes 2 and the conductive adhesive 5. Is cured, a sealing resin is injected into a gap between the semiconductor element 3 and the circuit board 1, and then the sealing resin is cured to obtain a flip-chip mounted body.

[0018]

As described above, according to the circuit board of the present invention, the conductor surface of the electrode conductor of the circuit board is polished to remove irregularities between the conductor surfaces. The conductive electrode of the circuit board and the bump of the semiconductor element can be stably connected, the connection portion has a low resistance value without variation, and the advantageous effect that a semiconductor device having a high yield can be provided can be obtained. In addition, an advantageous effect of preventing an increase in connection resistance value due to the covering with an oxide or a deposit can be obtained.

[Brief description of the drawings]

FIG. 1 is a side view schematically showing a bonding process of a flip chip mounting method according to the present invention.

FIG. 2 is a side view schematically showing a structure of a conductor electrode according to a second embodiment of the present invention.

FIG. 3 is a side view schematically showing a bonding process of a conventional flip chip mounting method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Circuit board for mounting 2 Conductive electrode 3 Semiconductor element 4 Bump 5 Conductive adhesive 6 Smooth surface by grinding 7 Conductive layer 8 DLC film

Claims (6)

[Claims] 1. A plurality of conductor electrodes formed at predetermined positions on a surface of a circuit board, wherein the surfaces of the plurality of conductor electrodes are polished so that the surfaces of the plurality of conductor electrodes are flush with each other. Circuit board for flip chip mounting. 2. The method according to claim 1, wherein the unevenness between the surfaces of the plurality of conductor electrodes is one.
2. The polishing method according to claim 1, wherein the polishing is performed to a thickness of 0 μm or less.
4. The flip-chip mounting circuit board according to claim 1. 3. A conductive layer formed by forming a film of carbon-based material at a plurality of predetermined positions on a circuit board and polishing the surface of the film so that the surface of the film is flush with the surface of the conductive layer. Forming a diamond-like carbon film of
A circuit board for flip-chip mounting, comprising a conductor electrode for connecting a semiconductor element. 4. A semiconductor element to be joined after a plurality of conductor electrodes are formed at predetermined positions on a surface of a circuit board, and the surfaces of the conductor electrodes are polished so that the surfaces of the plurality of conductor electrodes are flush with each other. Flip-chip mounting, wherein said electrode pad is pressed against said semiconductor electrode in a state where a conductive adhesive is adhered to said electrode pad, and said electrode pad and said conductive electrode are electrically connected. 5. The method according to claim 1, wherein unevenness between surfaces of the plurality of conductor electrodes is reduced by one.
5. The flip chip mounting method according to claim 4, wherein the polishing is performed to a thickness of 0 [mu] m or less. 6. A conductive layer is formed at a plurality of predetermined positions on the surface of a circuit board using a carbon-based material paste, and the surfaces of the conductive layers are polished so that the surfaces of the plurality of conductive layers are flush with each other. Forming a conductive electrode by forming a conductive diamond-like carbon film on the surface of the polished conductive layer, and attaching a conductive adhesive to an electrode pad of a semiconductor element to be joined; A flip chip mounting method, wherein an electrode pad is pressed against the semiconductor electrode to electrically connect the electrode pad and the conductor electrode.