Electrolysis: processes – compositions used therein – and methods – Electrolytic erosion of a workpiece for shape or surface...
Reexamination Certificate
2002-01-11
2004-08-03
Nicolas, Wesley A. (Department: 1742)
Electrolysis: processes, compositions used therein, and methods
Electrolytic erosion of a workpiece for shape or surface...
C205S665000, C205S666000, C205S667000, C216S041000, C216S043000, C216S044000, C204S22400M
Reexamination Certificate
active
06770188
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of fabricating a part comprising a conductive material and a part used in a sensor, an actuator or the like, comprising a conductive material and including a structure having a movable portion in the fields of a metal industry, a chemical industry, an electronic industry, a machine industry and the like.
2. Description of the Related Art
A conventional method of fabricating a part with a desired shape is generally performed by removing an unnecessary portion of a fabricating material utilizing mechanical machining technology or electric discharge machining technology. In a method utilizing mechanical machining technology, such as a cutting tool, by rotating either the cutting tool or the fabricating material and, at the same time, bringing the cutting tool and the fabricating material into contact with each other, the unnecessary portion of the fabricating material is removed to thereby finally obtain a part having a desired shape. Meanwhile, in a method utilizing electric discharge machining, a machining electrode having a front end shape in correspondence with a desired fabricating shape is produced, an interval between the machining electrode and the fabricating material is adjusted to a predetermined distance and by repeatedly producing an electric discharge in a pulse-like shape therebetween, a desired shape is achieved by removing the unnecessary portion of the fabricating material to thereby fabricate a part.
Meanwhile, a method of fabricating a part partially including a movable portion is generally performed by fabricating the individual elements utilizing various fabrication technologies such as mechanical machining technology and electricity discharge machining technology, described above, and thereafter, assembling the elements.
Further, in addition to such methods, and as shown by FIG.
3
and
FIG. 4
, there is generally used a method of forming a movable portion by a method of patterning a thin film or a thick film deposited on a substrate in a layered shape by photolithography. When the movable portion is formed by the method shown in FIG.
3
and
FIG. 4
, the following procedure is carried out.
At a portion of a flat base substrate
101
, there is deposited a sacrificing layer
102
comprising a material different from that of the base substrate
101
by a predetermined thickness (FIG.
3
(B)). Further, on the sacrificing layer
102
, there is deposited a structural body material layer
103
comprising a material different from that of the sacrificing layer
102
by a predetermined thickness (FIG.
3
(C)). Successively, the structural body material layer
103
is patterned into a desired shape.
First, a photoresist
301
is coated on the structural body material layer
103
(FIG.
3
(D)) and light is irradiated to the photoresist
301
via a photomask
302
having a pattern to be formed at the structural body material layer
103
to thereby expose the photoresist
301
(FIG.
3
(E)). Thereafter, there is formed a mask pattern for patterning the structural material layer
103
on the photoresist
301
by being subjected to steps of development, rinsing, post baking and so on (FIG.
4
(A)). In such a state, the substrate is dipped in an etching solution for dissolving the structural body material layer
103
to thereby etch a portion of the structural material layer
103
that is not coated by the photoresist
302
. When there is constituted a state (FIG.
4
(B)) in which the portion of the structural body material layer
103
which is not coated by the, photoresist
302
is penetrated to reach the sacrificing layer
102
, successively, the substrate is dipped in an etching solution which does not dissolve the base substrate
101
and the structural body material
103
and selectively dissolves only the sacrificing layer
102
to thereby remove the sacrificing layer
102
formed at the step of FIG.
3
(B) (FIG.
4
(C)). Finally, the photoresist
301
is removed and in, a structural body material layer
103
a movable portion
202
that is not tightly attached to the base substrate
101
can be formed (FIG.
4
(D)). In a state shown by FIG.
4
(D), a quadrangle of the movable portion
202
is only connected to a structural body fixing portion
201
via narrow beams and therefore, when force is applied to the movable portion
202
, the movable portion
202
is moved relatively to the base substrate
101
only by an amount in proportion to the force. Such a structure is utilized in, for example, a pressure sensor or an acceleration sensor.
However, there are a number of problems in the conventional part fabricating method. When the mechanical machining technology is utilized to the part fabricating method, there are following problems.
(1) Most of the fabricating material is removed and wasted to make a final shape of a part. Further, a long fabrication period of time is taken.
(2) A machinable shape is restricted depending on a kind of a fabricating machine used and therefore, in the case of fabricating a part having a complicated shape, many kinds of fabricating machines are needed and a number of steps of fabrication increases.
(3) The machining is carried out by bringing the cutting tool and the fabrication object into contact with each other and therefore, dissipation of the cutting tool is unavoidable. When the cutting tool is dissipated, there are problems caused, in that accuracy of fabrication is deteriorated, a fabricating surface is roughened and so on, therefore, the cutting tool is changed as necessary.
(4) Since fabrication is carried out by utilizing physical force produced between the cutting tool and the fabrication object and therefore, machinability is affected to hardness and tenacity of the fabrication material. Therefore, kinds and fabrication conditions of the cutting tool need to adjust in proportion to the material of the fabrication object.
(5) Smaller tip size of the cutting tool gives higher tip resolution of fabrication. However, there is a limit in miniaturizing tip size of the cutting tool because fabrication is carried out utilizing physical force. Further, similarly, it is necessary that the fabrication object is not deformed by the physical force operated in fabrication and therefore, there is a limit in a size of a machinable part.
Next, when the electro discharge machining technology is utilized to the part fabricating method, there are following problems.
(1) The fabrication shape is determined by the shape of the machining electrode, and therefore, it is necessary to fabricate the machining electrode having a appropriate shape in correspondence with a desired shape of machining. Usually, in fabricating the machining electrode, a wire cut electro discharge machine is used, two kinds of electro discharge machines are needed for fabricating the machining electrode and fabricating the part. Therefore, fabrication cost is increased.
(2) Similarly to mechanical machining, dissipation of the machining electrode is unavoidable and the machine electrode is changed as necessary. Further, in fabrication, position of the machining electrode has to be controlled in consideration of dissipation of the machining electrode. Therefore, the control method becomes complicated.
(3) In most of the cases, similarly to mechanical machining, most of the fabrication material is removed and wasted to make a final shape of a part. A long period of fabrication time is taken.
(4) In order to create a discharge, a high voltage needs to be applied, and therefore, energy consumption in fabrication is considerable. Further, there is a risk of producing a damaged layer on the surface after fabrication by discharge.
Further, in the case of fabricating a part that includes a movable portion according to the conventional method, the following problems have arisen. First, in the case of the method which includes the process of fabricating the individual elements constituting the part by utilizing various fabrication technologies such as mechanical machining technology
Furuta Kazuyoshi
Suda Masayuki
Watanabe Naoya
Adams & Wilks
Nicolas Wesley A.
Seiko Instruments Inc.
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