Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
1998-07-22
2002-09-17
Chang, Rick K. (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S832000, C029S837000, C029S841000, C029S739000, C257S775000, C257S738000, C257S772000, C257S773000, C257S778000, C174S260000, C361S768000, C361S773000, C361S774000
Reexamination Certificate
active
06449838
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of mounting a semiconductor device to a substrate and a mounted structure thereof and, more in particular, to a method of mounting a semiconductor device to a substrate by a flip-chip system and a mounting structure thereof.
2. Description of the Related Art
Accompanying with reduction in the size and lowering of the cost in electronic equipments in recent years, a structure for mounting semiconductor devices on a substrate at a high density has been simplified. A flip-chip system has been proposed as a high density mounting structure of semiconductor devices having such a simplified structure.
In the flip-chip system, a semiconductor device with a plurality of bump electrodes being mounted to at least one surface thereof is connected to a circuit substrate with the surface being faced downward, which is disclosed in Japanese Patent Laid-Open Hei 4-82241. Now, the conventional flip-chip mounting structure will be described with reference to FIG.
1
.
Referring to
FIG. 1
, an insulating resin layer
2
made of a material such as rubber having elastic recovery force is formed on a substrate
1
. Further, a mounting pad
3
is formed on the insulating resin layer
2
by means of sputtering or vapor deposition. A sealing resin
5
is coated to a region on the insulating resin layer
2
in which a semiconductor device
4
is mounted to the substrate
1
. On the other hand, a plurality of bump electrodes
6
are formed to the surface of the semiconductor device
4
facing the substrate
1
.
In the manufacturing method of the conventional mounting structure, at first, a plurality of the bump electrodes
6
disposed on the lower surface of the semiconductor device
4
and the mounting pad on the substrate
1
are aligned and then the semiconductor device
4
is bonded under pressure on the substrate
1
. In this case, since the sealing resin
5
between the bump electrode
6
of the semiconductor device
4
and the mounting pad
3
on the substrate
1
is extruded, the bump electrode
6
and the mounting pad
3
are connected electrically with each other. In this conventional flip-chip mounting structure, since the insulating resin layer
2
having the elastic recovery force is formed between the substrate
1
and the mounting pad
3
, electric connection between the bump electrode
6
and the mounting pad
3
can be held stably by the elastic recovery force of the insulating resin layer
2
and the contracting force of the sealing resin
5
.
However, in the conventional flip-chip mounting structure, the elastic recovery force of the insulating resin layer
2
or the contracting force of the sealing resin
5
tends to suffer from degradation in an accelerated test such as a temperature cycle test and, as a result, the amount of heat expansion of the sealing resin
5
is greater than the contracting force thereof and the elastic recovery force of the insulating resin layer
2
, to form a gap between the bump electrode
6
and the mounting pad
3
. Accordingly, the gap formed between the bump electrode
6
and the mounting pad
3
causes connection failure between the semiconductor device
4
and the substrate
1
.
Further, in the conventional flip-chip mounting structure described above, the semiconductor device
4
and the substrate
1
are connected in a state where the mounting pad
3
and the insulating resin layer
2
are deformed elastically. Accordingly, when the balance between the contracting force of the sealing resin
5
and the elastic recovery force of the insulating resin layer
2
should change by the temperature change, the deformed state of the mounting pad
3
changes correspondingly. Thus, considerable stresses exert on the mounting pad
3
due to temperature change and, as a result, the mounting pad
3
is damaged to sometimes cause disconnection or the like.
Further, in the conventional flip-chip structure, since it is necessary to form the insulating resin layer
2
having the elastic recovery force on the substrate
1
, it cannot avoid the complexity for the production step and increase of the production cost.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method of mounting a semiconductor device to a substrate and a mounted structure thereof, capable of improving the reliability in a connected state.
It is another object of the present invention is to provide a method of mounting a semiconductor device to a substrate and a mounted structure thereof capable of maintaining a stable connection state to the increase of temperature or change of circumstantial temperature.
To achieve the above objects, the structure for mounting a semiconductor device to a substrate comprises a mounting pad disposed on the substrate, a sealing resin provided on the substrate on which the semiconductor device is to be mounted, and a plurality of projecting electrodes disposed on a surface of the semiconductor device facing the substrate, and each of the projecting electrodes including a substantially spherical portion and a pointed portion in contact under pressure with the mounting pad and deformed such that a contact portion with the mounting pad is enlarged from a point to a plane.
Further, to achieve the above objects, the method of mounting a semiconductor substrate having a plurality of projecting electrodes to a substrate, on which a mounting pad is formed and an sealing resin is provided, wherein the method comprises the steps of pressing the projecting electrode to the mounting pad and thereby deforming a pointed shape portion at the top end of each the projecting electrode and, hardening the sealing resin.
REFERENCES:
patent: 4997791 (1991-03-01), Ohuchi et al.
patent: 5037780 (1991-08-01), Fujimoto et al.
patent: 5070604 (1991-12-01), Banba et al.
patent: 5071787 (1991-12-01), Mori et al.
patent: 5084344 (1992-01-01), Harada et al.
patent: 5132772 (1992-07-01), Fetty
patent: 5186383 (1993-02-01), Melton et al.
patent: 5316610 (1994-05-01), Tamaki et al.
patent: 5329423 (1994-07-01), Scholz
patent: 5348214 (1994-09-01), Nishiguchi et al.
patent: 5363277 (1994-11-01), Tanaka
patent: 5386624 (1995-02-01), George et al.
patent: 5410807 (1995-05-01), Bross et al.
patent: 5478007 (1995-12-01), Marrs
patent: 5518964 (1996-05-01), DiStefano et al.
patent: 5595934 (1997-01-01), Kim
patent: 5615824 (1997-04-01), Fjelstad et al.
patent: 5869904 (1999-02-01), Shoji
patent: 4-82241 (1992-03-01), None
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