Semiconductor device manufacturing: process – Packaging or treatment of packaged semiconductor
Reexamination Certificate
1998-10-23
2001-03-06
Elms, Richard (Department: 2824)
Semiconductor device manufacturing: process
Packaging or treatment of packaged semiconductor
C438S118000
Reexamination Certificate
active
06197612
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a semiconductor chip mounting apparatus and a method of mounting a semiconductor chip, particularly to the semiconductor chip mounting apparatus and the method thereof for use in mounting a semiconductor chip on a substrate.
In mounting a semiconductor chip, such as a bear chip on a substrate, some mounting methods are generally used. In one of the mounting methods, for example, metal projections formed on electrodes of the bear chip are connected to electrodes of a substrate by solder, or the like. In another one of the mounting methods, gold projections are formed on electrodes of a bear chip so as to be thermally crimped to gold-plated electrodes of a substrate at a high temperature.
In the mounting methods, both the bear chip and the substrate are heated up to a high temperature during mounting process and thereafter naturally cooled down to an ordinary temperature. However, a great stress is imposed on a connected portion during the cooling process due to a difference between coefficient of thermal expansion of the bear chip and that of the substrate. When the substrate is made of an organic material such as glass epoxy resin, and the like, the difference of the coefficient of thermal expansion becomes serious. Accordingly, the great stress is imposed on the connected portion during the cooling process, since a shrinkage ratio of the substrate is larger than that of the bear chip. As a result, the connected portion is easily destroyed.
It is desired that the stress is reduced to obtain a reliable connected portion. Then, some proposals have been made to reduce the stress conventionally. A proposal is exemplified, as a first prior art, in unexamined Japanese Patent Publication No. Sho 63-237426, namely, 237426/1988. In the first prior art, it is attempted that a difference of amounts of thermal expansion between a semiconductor chip, such as a flip chip IC(Integrated Circuit) and a substrate is reduced by using expansion and shrinkage of resin at a comparatively low temperature for connecting the flip chip IC and the substrate. Thereby, the resin has already been fastened when the mounting process is finished to start a next cooling process. As a result, a thermal stress on a connected portion due to the difference of coefficient of thermal expansion is dispersed to prevent the connected portion from being destroyed.
However, as the connection is achieved only by a shrinkage of the resin, it becomes difficult to obtain reliability such as a temperature cycle resistant characteristic, or the like. In addition, boids are inevitably generated in the resin when the flip chip IC and the substrate are rapidly heated up to a high temperature. For preventing the boids from being generated, it therefore takes a long time to heat the flip chip IC and the substrate up to a high temperature. In view of a time to heat them up to a high temperature as well as a time to fasten the resin, the mounting method disclosed as the first prior art takes a time several times longer than the above-mentioned generally used mounting methods. As a result, a productivity per production facility unit is not so good in the first prior art.
On the other hand, another proposals are exemplified, as a second prior art, in unexamined Japanese Patent Publications No. Hei 2-14536, namely, 14536/1990, No. Hei 7-7042, namely, 7042/1995, or No. Hei 5-326585, namely, 326585/1993. In each second prior art, it is attempted that a difference of amounts of thermal expansion between a semiconductor chip and a substrate is reduced by a design of a structure of the semiconductor chip or a design of a structure of mounting the semiconductor chip on the substrate. However, members of the semiconductor chip and the substrate becomes very expensive in the second prior art. Furthermore, the second prior art cannot completely resolve the aforesaid problem of the thermal stress on the connected portion. Namely, the thermal stress is imposed, more or less on the connected portion, since a difference of amounts of thermal expansion between the semiconductor chip and the substrate cannot be substantially eliminated.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a semiconductor chip mounting apparatus and a method of mounting a semiconductor chip by which a high productivity can be obtained and in which a thermal stress on a connected portion can be reduced to a desirable extent at a low cost.
It is another object of the present invention to provide a semiconductor chip mounting apparatus and a method of mounting a semiconductor chip of the type described which can be widely applied, for example, a semiconductor chip generally circulated in market for the purpose of connection by wire bonding or an inexpensive substrate made of a basic material of glass epoxy.
Other objects of this invention will become clear as the description proceeds.
According to an aspect of this invention, there is provided a semiconductor chip mounting apparatus for use in mounting a semiconductor chip on a substrate, comprising; mounting means for mounting the semiconductor chip on the substrate; a loader which supplies the substrate to the mounting means; an unloader which contains the substrate having the semiconductor chip mounted by the mounting means into a magazine, the magazine being set on the unloader; first heating means which is located between the mounting means and the unloader and which heat the substrate having the semiconductor chip to be kept at a predetermined temperature; and second heating means which is located on the unloader and which previously heat the magazine to be kept at the predetermined temperature before the substrate having the semiconductor chip is contained into the magazine.
The second heating means may surround the magazine on the unloader.
The semiconductor chip mounting apparatus may further comprise a temperature control system for controlling temperatures of the first and the second heating means, the temperatures of the first and the second heating means may be controlled by the temperature control system independently from each other.
The magazine may have a plurality of shelves each of which contains the substrate having the semiconductor chip, the unloader may have an elevator by which the magazine freely rise and fall so as to contain the substrate having the semiconductor chip into any one of the shelves.
The second heating means may be tall enough in height to heat a whole of the magazine even though the magazine is in the uppest or the lowest position available by the elevator.
The unloader may have a preliminary buffer, the magazine may be previously heated within the preliminary buffer.
The unloader may have a drain buffer, the magazine may be contained into the drain buffer to be kept at the predetermined temperature until the substrate having the semiconductor chip is sent to a next process.
According to another aspect of this invention, there is provided a semiconductor chip mounting apparatus for use in mounting a semiconductor chip on a substrate, comprising: mounting means for mounting the semiconductor chip on the substrate; a loader which supplies the substrate to the mounting means; resin sealing means for sealing a connection between the semiconductor chip and the substrate by a resin after the semiconductor chip is mounted on the substrate; an unloader which contains the substrate having the semiconductor chip sealed by the resin sealing means; and heating means which is located between the mounting means and the resin sealing means, both inclusive, and which heat the substrate having the semiconductor chip to be kept at a predetermined temperature until the connection is sealed by the resin.
According to still another aspect of this invention, there is provided a method of mounting a semiconductor chip on a substrate, the semiconductor chip and the substrate being prepared in a known manner, the method comprising the steps of: supplying the substrate; mounting the semiconductor chip on the substrate;
Elms Richard
Lebentritt Michael S.
McGinn & Gibb PLLC
NEC Corporation
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