JPH08236578A - Flip-chip mounting method for semiconductor element and adhesive used for this mounting method - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a flip-chip mounting method for a semiconductor element in which the soldering step is reduced and the semiconductor element after mounting is less likely to peel off from the substrate, and an adhesive used in this mounting method. [Structure] A film adhesive having a raised central portion is pressure-bonded from above a substrate having a substrate pad. The semiconductor element on which the bump is formed is superposed so that the substrate pad and the bump are in contact with each other, and the semiconductor element is pressure-bonded to the adhesive via the bump. Moreover, the substrate pad and the bump are electrically connected by this pressure bonding. Finally heat from the outside,
The adhesive is melted and fixed to mechanically connect the substrate and the semiconductor element.

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 semiconductor device and an adhesive used for the mounting method, and more particularly to a method for mounting a semiconductor device on a flip chip and an adhesive used for the mounting method.

[0002]

2. Description of the Related Art Conventionally, in a flip chip mounting method for a semiconductor element, a bump provided on the semiconductor element is electrically connected to a substrate pad provided on a substrate. Then, the semiconductor element and the substrate are mechanically connected with a liquid adhesive or the like, and the semiconductor element is mounted on the substrate.

This type of flip-chip mounting method does not require terminals as compared with a mounting method in which terminals such as bonding wires are formed on the semiconductor element. Therefore, the semiconductor element on the substrate in the mounting structure after mounting the semiconductor element The effect is high packaging density.

FIG. 4 is a process chart showing a conventional flip-chip mounting method for a semiconductor device.

First, in step (a) of FIG. 4, a substrate 1 made of glass epoxy resin is arranged with the substrate pad 2 side facing upward. The substrate pad 2 is electrically connected to the wiring on the substrate 1. Subsequently, in step (b), the substrate pad 2
Print solder paste or apply solder plating on top. Then, in the step (c), the bump 5 made of gold is used.
The semiconductor element 4 on which the bumps are formed is stacked so that the bumps 5 and the solder 6 are in contact with each other, and in the step (d),
The board pad 2 and the bump 5 are soldered by applying heat from the outside. In this step, the substrate 1 and the semiconductor element 4 are temporarily connected and electrically connected. Such a process is described in, for example, JP-A-59-35439.

Further, in the step (e), a liquid sealing resin 7 made of epoxy resin is applied to the substrate 1 and the semiconductor element 4 from a portion of the semiconductor element 4 where the bumps 5 are not formed.
Inject between and. Thereafter, heat is applied from the outside to fix the sealing resin 7 to the substrate 1 and the semiconductor element 4.
Are connected mechanically.

[0007]

In the conventional flip-chip mounting method for a semiconductor element, a liquid sealing resin is injected between the substrate and the semiconductor element to connect the substrate and the semiconductor element. Air is mixed into the resin when the resin is injected, and bubbles are formed when the resin is fixed. Since the bubbles weaken the adhesive force, there is a problem that the substrate is easily peeled after the semiconductor element is mounted on the substrate.

Further, when the substrate is made of glass epoxy resin, heat resistance is weak, so that there is a problem that the substrate is deformed by heating at the time of soldering the substrate and the semiconductor element.

Furthermore, since the sealing resin is liquid, it is difficult to inject a predetermined amount of the resin, and there is a problem that the work site becomes dirty due to liquid leakage or the like during the injection.

The object of the present invention is to solve the above-mentioned problems,
It is an object of the present invention to provide a flip-chip mounting method for semiconductor devices, which simplifies the mounting process and has high mass productivity.

[0011]

In order to achieve the above-mentioned object, according to the present invention, a semiconductor device is mounted on a substrate by connecting bumps formed on the semiconductor device and substrate pads formed on the substrate. In a flip chip mounting method of a semiconductor element to be mounted, a first step of pressing a solid adhesive whose central portion is raised to a substrate, a second step of pressing a solid adhesive to the semiconductor element, a bump and a board pad. And a fourth step of fixing the substrate and the semiconductor element by applying heat to the solid adhesive.

In the solid adhesive, the center of the first surface in contact with the substrate is higher than the center of the second surface in contact with the semiconductor element. Become.

[0013]

By adopting the above structure, the present invention uses a solid adhesive and further forms the central portion of the adhesive by bulging, so that the central portion of the adhesive is pressed when the adhesive is pressed onto the substrate and the semiconductor element. First, the substrate and the central portion of the semiconductor element are in contact with each other. Subsequently, since the adhesive contacts the substrate and the semiconductor element in a direction away from the center of the adhesive, air is removed to the outside without remaining inside.

Further, since the substrate and the semiconductor element are pressure-bonded to the viscous solid adhesive, the connection between the substrate substrate pad and the bump does not require temporary connection by solder.

Furthermore, since the adhesive is solid, it is easy to use, and the work site is not stained by the use of a liquid adhesive due to liquid leakage at the time of injection.

[0016]

The present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram for explaining a flip-chip mounting method for a semiconductor device showing an embodiment of the present invention.

First, in step (a) of FIG. 1, a substrate pad 2 electrically connected to wiring on the substrate is provided on a substrate 1 made of glass epoxy resin. Also,
A film adhesive 3 to be described in detail later is pressed from above the substrate 1. By this pressure bonding, the adhesive 3 and the substrate 2 are fixed.

Subsequently, in the same step (b), the semiconductor element 4 on which the bumps 5 made of gold are formed is superposed on the substrate 1 via the adhesive 3 and the semiconductor element 4 is pressed to the adhesive 3. . At this time, the adhesive 3 and the semiconductor element 4 are pressed, and the substrate pads 2 and the bumps 5 come into contact with each other to be electrically connected.

Finally, in the same step (C), the adhesive 3 is melted and fixed by applying heat from the outside, so that the substrate 1
And the semiconductor element 4 are firmly connected.

Next, the film adhesive 3 will be described in detail with reference to FIG.

In the figure, bumps 32 and 33 are formed on the adhesive 3 so that the central portion has the maximum thickness.

Therefore, in the above-mentioned press-fit connection between the substrate 1 and the adhesive 3 shown in the step (a) of FIG. 1, first, the central portion of the adhesive 3 is pressed against the central portion of the substrate 1. Then, in the subsequent pressure bonding of the substrate 1 and the adhesive 3, the substrate 1 and the adhesive 3 are pressed from the center of the adhesive 3 toward the outside. Similarly, in the press-fit connection between the semiconductor element 4 and the adhesive 3 in the step (b) of FIG. From the center to the outside.

In such a pressure bonding step, the adhesive 3 is solid and in the form of a film, and the pressure bonding with the substrate 1 or the semiconductor element 4 is performed from the center to the outside, so that the adhesive 3 With the pressure bonding, air is pushed out of the substrate 1 or the semiconductor element 4. As described above, since the adhesive 3 and the substrate 1 or the semiconductor element 4 are pressure-bonded without any gap, bubbles are not formed by the heating in the step (c) of FIG.

Returning to FIG. 2 again, of the ridges 32 and 33, the ridge 32 on the side pressed against the substrate 1 has a larger size than the ridge 33 on the side pressed against the semiconductor element 4. This is because the surface roughness of the substrate 1 and the semiconductor element 4, that is, the undulation, is larger in the substrate 1. Since the substrate 1 has a larger undulation on the surface, air is more likely to accumulate than the semiconductor element 4. Therefore, air is applied to the substrate 1 when the substrate 1 and the adhesive 3 are pressed as described above.
In order to extrude more, it is better to make the protrusion 32 larger. On the other hand, in the ridge 33 that is pressed against the semiconductor element 4, the undulation on the surface of the semiconductor element 3 is smaller than that of the substrate 1, and thus the ridge may be reduced. By the way, if the height of the protrusion 33 is made large as in the case of the protrusion 32, air can be reliably pushed out from the semiconductor element 4. However, when manufacturing the film adhesive 3, the smaller the height of the protrusion is, the more the manufacturing variation is suppressed. The semiconductor element 4
It is desirable that the ridge of the ridge 33 to be pressed is formed small.

Although the adhesive 3 is made of an epoxy resin in this embodiment, its composition is not particularly limited in this embodiment as long as it is melted and fixed at a low temperature when heat is applied.

FIG. 3 is a view for explaining a flip-chip mounting method of a semiconductor device according to a second embodiment of the present invention.

First, in step (a) of FIG.
When the semiconductor element 4 on which the bumps 5 are formed is pressed from above, the adhesive 3 and the semiconductor element 4 are fixed. Subsequently, in the same step (b), the substrate 1 on which the substrate pads 2 are formed is pressure-bonded to the adhesive 3 such that the substrate 1 is overlaid on the semiconductor element 4 via the adhesive 3. At this time, the adhesive 3 and the substrate 1 are fixed, and the substrate pad 2 and the bump 5 are in contact with each other and electrically connected. Finally, in the same step (C), by applying heat from the outside, the adhesive 3 is melted and fixed, and the substrate 1 and the semiconductor element are mechanically connected.

The second embodiment is different from the first embodiment shown in FIG. 1 in that the adhesive 3 is pressed on the semiconductor element 4 first. This means that the present invention does not matter in the order of the working steps, that is, the adhesive 3 may be pressure-bonded to either the substrate 1 or the semiconductor element 4 first. Therefore, the present invention can provide the work process with a range of selectivity at the work site.

[0030]

As described above, the flip-chip mounting method for a semiconductor device according to the present invention uses a film-like adhesive, and furthermore, the center of the adhesive is raised to form the adhesive. No air is mixed when the substrate and the semiconductor element are pressed, and no air bubbles are formed at the connection portion with the substrate after the semiconductor element is mounted. Therefore, the semiconductor element after mounting is hard to peel off from the substrate.

When mounting a semiconductor element on a substrate made of a material having low heat resistance such as glass epoxy resin, the substrate and the semiconductor element are pressure-bonded to the film-like adhesive to bond the substrate pad and the bump. In order to make an electrical connection, the substrate and the pad, the semiconductor element and the bump are fixed to each other via the film adhesive without performing the temporary connection and the electrical connection by the solder. Therefore, the soldering process can be reduced, the substrate is not deformed by the heating when the solder is melted, and the mounting process can be further simplified. Since the heating during the melting of the adhesive is lower than the heating during the melting of the solder, the substrate is not deformed.

Furthermore, since the film-like adhesive is solid, it is easy to use a predetermined amount of the adhesive, and a liquid adhesive may be used to contaminate the work site due to liquid leakage during injection. Absent.

[Brief description of drawings]

FIG. 1 is a process diagram illustrating a mounting process of a flip-chip mounting method of a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a front view illustrating details of the film adhesive shown in FIG. 1;

FIG. 3 is a process diagram illustrating a mounting process of a flip-chip mounting method of a semiconductor device according to a second embodiment of the present invention.

FIG. 4 is a process diagram for explaining a mounting process of a conventional flip-chip mounting method for a semiconductor element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Substrate pad 3 ... Film adhesive 4 ... Semiconductor element 5 ... Bump 6 ... Solder 7 ... Sealing resin 32 ... Substrate side protrusion 33 ... Small bumps on semiconductor device

Claims (10)

[Claims] 1. A flip-chip mounting method for a semiconductor element, wherein the semiconductor element is mounted on the substrate by connecting a bump formed on the semiconductor element to a substrate pad formed on the substrate. First, the solid adhesive is pressed onto the substrate.
The second step of pressing the solid adhesive onto the semiconductor element, and the third step of electrically connecting the bump and the substrate pad.
And a fourth step of fixing the substrate and the semiconductor element by heating to the solid adhesive. A flip chip mounting method for a semiconductor element. 2. The first step, wherein: a fifth step in which a central portion of the solid adhesive and a central portion of the substrate are pressure-bonded; and a step away from the central portion of the solid adhesive. 6. The method according to claim 1, further comprising: a sixth step of sequentially pressing the solid adhesive and the substrate. 3. A seventh step in which the central portion of the solid adhesive and a central portion of the semiconductor element are pressure-bonded to each other in the second step; and a direction away from the central portion of the solid adhesive. The flip chip mounting method for a semiconductor device according to claim 1, further comprising: an eighth step in which the solid adhesive and the semiconductor device are pressure-bonded to each other. 4. A method of mounting a semiconductor element on a substrate, comprising: a first step of inserting a solid adhesive between the semiconductor element and the substrate; and a step between the semiconductor element and the substrate. A semiconductor element mounting method comprising: a second step of eliminating air; and a third step of fixing the substrate and the semiconductor element by heating the solid adhesive. 5. The method according to claim 1, wherein the second step includes a fourth step of pressing the solid adhesive to the semiconductor element, and a fifth step of pressing the solid adhesive to the substrate. The method for mounting a semiconductor device according to claim 4. 6. An adhesive used for mounting a semiconductor element on a substrate, wherein the adhesive is a solid adhesive having a raised central portion. 7. The central portion of the first surface of the adhesive that contacts the substrate is raised more than the central portion of the second surface that contacts the semiconductor element. Adhesive for semiconductor mounting. 8. The adhesive according to claim 6, wherein the adhesive is formed in a film shape. 9. The adhesive according to claim 6, wherein the adhesive is made of a resin that melts and adheres at a low temperature. 10. The semiconductor mounting adhesive according to claim 9, wherein said adhesive is made of an epoxy resin.