Semiconductor device manufacturing: process – Packaging or treatment of packaged semiconductor
Reexamination Certificate
2001-04-20
2002-11-12
Sherry, Michael (Department: 2829)
Semiconductor device manufacturing: process
Packaging or treatment of packaged semiconductor
C438S111000, C438S457000
Reexamination Certificate
active
06479318
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device substrate and a semiconductor device fabrication method, particularly to a semiconductor device substrate in which a solder resist is applied onto a predetermined substrate and a semiconductor device fabrication method using the substrate.
2. Description of the Background Art
Demands on semiconductor devices have been recently increased in the field of electronics. A semiconductor device is generally constituted by forming a wiring layer made of a metal, such as copper, on an insulating substrate, such as a glass-epoxy substrate, and mounting of a semiconductor element on the wiring layer. The semiconductor element and the wiring layer are connected to each other by solder or a bonding wire. In this case, so-called solder resist is formed on the substrate in order to prevent a chemical change of the wiring-layer surface and to prevent formation of a solder bridge between adjacent solder junctions.
FIG. 13
is a perspective view of a conventional semiconductor device substrate on which a solder resist is formed. Referring to
FIG. 13
, a semiconductor device substrate
10
has a plate-shaped substrate
1
and a solder resist
5
formed on the substrate
1
. The substrate
1
is almost rectangular and has a major side
1
a
and a minor side
1
b
. The substrate
1
is made of the so-called glass-epoxy substrate formed by impregnating glass fiber with epoxy resin and has a superior insulating property. A printed wiring layer (not illustrated) is formed on the surface of the substrate
1
. To protect the surface of the printed wiring layer, a solder resist
5
is applied to the surface of the substrate
1
. The solder resist
5
is made of, for example, epoxy resin and a hole
5
a
is formed on the solder resist
5
. The hole
5
a
exposes the printed wiring layer formed on the surface of the substrate
1
. Thereby, it is possible to electrically connect the exposed printed wiring layer with a semiconductor device mounted on the layer. Moreover, because the printed wiring layer is covered with the solder resist
5
at other portions, it is possible to prevent the surface of the printed-wiring layer from oxidizing. The solder resist
5
is formed on the surface of the substrate
1
through screen printing.
Problems of the prior art are described below by referring to the accompanying drawings.
FIG. 14
is a perspective view of a substrate shown to explain problems of the prior art. Referring to
FIG. 14
, the substrate
1
is greatly different from the solder resist
5
in linear expansion coefficient in general. Specifically, the substrate
1
has a smaller linear expansion coefficient because it contains glass fiber. However, the solder resist
5
has a linear expansion coefficient larger than that of the substrate
1
because the solder resist
5
is made of only an organic matter. Therefore, the substrate
1
is warped due to cooling or heating in the cooling process after forming the solder resist
5
or the bonding process for mounting a semiconductor element on the solder resist
5
after formed. Therefore, when housing the semiconductor device substrate
10
in a magazine
50
by mounting the substrate
10
on a rail
30
, pushing it with a pusher
40
, and conveying it in the direction shown by an arrow
11
, the substrate
10
is warped and thereby, it is difficult to automatically convey the substrate
10
. As a result, problems occur that the substrate
10
is incorrectly conveyed and fabrication processes are complicated.
SUMMARY OF THE INVENTION
Therefore, the present invention is made to solve the above problems and its object is to provide a semiconductor device substrate to be easily conveyed and a semiconductor device fabrication method using the substrate.
A semiconductor device fabrication method according to an aspect of the present invention includes the steps of forming a layer having a linear expansion coefficient A different from that of a semiconductor element mounting, plate-shaped substrate having major and minor sides and containing an organic matter on the substrate, warping the substrate with the layer formed on it along its minor-side direction, and conveying the warped substrate.
According to the above steps, the substrate is not warped along its major-side direction because it is warped along its minor-side direction. As a result, it is possible to decrease the whole warp of the substrate and easily convey the substrate.
It is preferable that the step of warping the substrate in its minor-side direction includes previously adjusting linear expansion coefficients of a substrate so that the difference between the linear expansion coefficient A and the linear expansion coefficient B of the substrate in its minor-side direction becomes relatively large and the difference between the linear expansion coefficient A and the linear expansion coefficient C of the substrate in its major-side direction becomes relatively small. In this case, only by adjusting linear expansion coefficients of the substrate, it is possible to securely warp the substrate along its minor-side direction in the subsequent step.
Moreover, it is more preferable that previously adjusting linear expansion coefficients of a substrate includes adjusting linear expansion coefficients in major- and minor-side directions by arranging a plurality of first fibers extending in the major-side direction of the substrate and a plurality of second fibers extending in the minor-side direction of the substrate in the substrate and adjusting densities of the first and second fibers. In this case, it is possible to easily control linear expansion coefficients in major- and minor-side directions only by adjusting densities of the first and second fibers.
It is still more preferable that the first and second fibers are glass fibers and the substrate contains matrix epoxy resin for covering the glass fibers.
It is still more preferable that the step of warping the substrate in its minor-side direction includes pressing the surface of the substrate so that the substrate is warped along its minor-side direction. In this case, by pressing the surface of the substrate, it is possible to warp the substrate along its minor-side direction through a simple step.
It is still more preferable that the step of warping the substrate along its minor-side direction includes attracting the surface of the substrate so that the substrate is warped in its minor-side direction. In this case, by attracting the surface of the substrate, it is possible to warp the substrate along its minor-side direction through a simple step.
It is still more preferable that the step of warping the substrate along its minor-side direction includes heating the substrate and then cooling the substrate and warping the substrate. In this case, because the substrate is heated, then cooled, and warped, the warped substrate is not easily warped in other directions. As a result, it is possible to securely warp the substrate.
It is still more preferable that a layer contains at least one selected from the group consisting of melamine resin, epoxy resin, acrylic resin, and polyimide resin. In this case, because these resins respectively constitute a solder resist, it is possible to form a solder resist on the substrate.
It is still more preferable that a semiconductor device fabrication method further includes a step of forming a conductive layer on a substrate before forming a layer and a step of forming a layer includes forming the layer so as to expose a part of the surface of the conductive layer. In this case, it is possible to protect the conductive layer by the layer and electrically connect a semiconductor element to the exposed part of the surface of the conductive layer.
It is still more preferable that the step of forming the layer includes forming a layer having a hole reaching the conductive layer on the substrate on which the conductive layer is formed. The semiconductor device fabrication method further includes mounting a semic
Matsuo Itaru
Miyamura Kayo
Ryu Hiroshi
Geyer Scott B.
Leydig , Voit & Mayer, Ltd.
Mitsubishi Denki & Kabushiki Kaisha
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