Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making electrical device
Reexamination Certificate
2001-09-21
2003-10-28
Huff, Mark F. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making electrical device
C430S314000, C430S317000, C430S318000, C430S322000, C029S592100, C029S603130, C029S603140, C360S313000, C360S315000
Reexamination Certificate
active
06638691
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for fabricating a plate-type magnetic resistance (hereinafter referred to as “MR”) sensor chip element, which is used for controlling rotational speeds of capstan motors for use in VCR, camcoders, and the like. More particularly, the present invention relates to the use of a glass wafer in fabricating a plate-type MR sensor chip simply and easily.
2. Description of the Prior Art
In order to better understand the background of the invention, a description will be given of a fabrication method of a conventional MR sensor chip in conjunction with FIG.
1
. For the fabrication of a conventional MR sensor chip, to begin with, sensing parts
21
, serving as characteristic membrane detectors, are formed on a ceramic glass sheet
11
while terminal parts are patterned on one end of the ceramic glass sheet
11
, as illustrated in FIG.
1
. The resulting structure is diced into individual rectangular MR sensor chips
20
.
Each rectangular MR sensor chip is bonded onto a chip holder
30
made of an insert injection via an adhesive. A lead frame
30
is connected to the terminal part
22
of the MR sensor chip
20
by soldering, followed by coating an epoxy resin
50
over the terminal part to protectively insulate the solder connection between the lead frame
30
and the terminal part
22
.
The conventional MR sensor chip
20
fabricated as in above is mounted at one side of a magnet
70
on a motor board
60
in such a way that the MR sensor chip
20
stands facing the magnet to control the rotational speed of the magnet
70
, as shown in FIG.
1
.
As disclosed in the above description, the fabrication of the conventional MR sensor chip requires complex processes, including insert injection for molding the chip holder
10
for fixing the MR sensor chip
20
, soldering for connecting the lead frame
30
to the terminal part of the MR sensor chip
20
, and application of the epoxy resin
50
to insulate the soldering portion.
Particularly, the ceramic glass sheet
11
of the MR sensor chip
20
is expensive and thus imposes an economic burden on both manufacturers and consumers. Both the sensing part
21
and the terminal part
22
are integrally formed onto the ceramic glass sheet
11
. However, since the terminal part
22
protrudes from the surface of the ceramic glass sheet
11
, insulating epoxy resin
50
is required to be applied on the soldering
40
, but this treatment makes the terminal part
22
more prominent. When the MR sensor chip
20
fixed to the chip holder
10
is mounted onto the motor board
60
, there occurs interference between the magnet, serving as a rotor, and the projection of the epoxy resin coated on the terminal part
22
.
A solution to this problem is the use of processed ceramic wafers or photosensitive glass which allows the terminal part to be formed on the back side. However, this solution is economically unfavorable because the substrates are very expensive and the fabricating process is complicated.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to overcome the above problems encountered in prior arts and to provide a method for fabricating an MR sensor chip easily and simply.
It is another object of the present invention to provide a method for fabricating a plate type MR sensor chip which is structured to have a terminal part on both sides thereof and thus can be mounted onto a board of a magnet without the aid of a separate holder.
Based on the present invention, the above objects could be accomplished by a provision of a method for fabricating a plate type magnetic resistance sensor chip, comprising the steps of: establishing sensing parts by depositing a characteristic membrane composed of NiCo and NiFe at 200 to 500° C. to a thickness less than 1,000 Å(Angstrom) on a surface of a glass wafer, exposing the membrane to light, and etching the membrane in a predetermined pattern; forming a protective film atop each of the sensing parts by depositing a SiO
2
membrane to a thickness of 0.2 to 0.7 &mgr;m over the glass wafer, exposing the SiO
2
membrane to light, and etching the SiO
2
membrane in the same pattern as in the sensing part; subjecting the resulting structure to sand blasting to form through-holes at every corner of the sensing parts; depositing a NiFe film around the through-holes on both sides of the glass wafer and within the through-holes; and dicing the glass wafer into individual rectangular magnetic resistance sensor chips in such a way that each magnetic resistance sensor chip has four arc corners with a NiFe conductor established at every arch corner on both sides of the wafer glass, said NiFe conductor serving as a terminal part.
REFERENCES:
patent: 3908194 (1975-09-01), Romankiw
patent: 4802043 (1989-01-01), Sato et al.
patent: 5049809 (1991-09-01), Wakatsuki et al.
patent: 5274521 (1993-12-01), Miyauchi et al.
patent: 6075710 (2000-06-01), Lau
Joung Ho-Chul
Kang Eung-Cheon
Chacko Davis Daborah
Huff Mark F.
Lowe Hauptmann Gilman & Berner LLP
Samsung Electro-Mechanics Co. Ltd.
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