Semiconductor device manufacturing: process – Semiconductor substrate dicing
Reexamination Certificate
2002-10-17
2004-10-19
Lee, Hsien-Ming (Department: 2823)
Semiconductor device manufacturing: process
Semiconductor substrate dicing
C438S462000, C438S464000
Reexamination Certificate
active
06806167
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of making a chip-type electronic component for surface-mounting on a printed wiring board. The present invention also relates to a chip-type electronic component obtained by such a method.
2. Description of the Related Art
FIG. 13
illustrates an example of prior art chip-type resistor. The illustrated resistor
21
includes a substrate
22
formed of alumina ceramic material. The substrate
22
has an upper surface
22
a
formed with a pair of first upper electrodes
23
. Further, the substrate
22
has side surfaces
22
b
formed with side electrodes
24
and a lower surface
22
c
formed with lower electrodes
25
. The upper surface
22
a
of the substrate
22
is provided with a resistor element
26
connecting the first upper electrodes
23
to each other. The resistor element
26
is covered with a first overcoat layer
27
. The first overcoat layer
27
is covered with a second overcoat layer
29
. On each of the first upper electrodes
23
A is formed a second upper electrode
28
.
The chip-type resistor
21
is manufactured by the process steps (T1-T12) shown in FIG.
14
. First, an aggregate board
11
formed of alumina ceramic material as shown in
FIG. 15
is prepared. The aggregate board
11
includes a plurality of rectangular regions
12
defined therein. Each of the regions
12
corresponds to the substrate
22
of one resistor
21
shown in FIG.
13
. Reference signs
13
and
14
in
FIG. 15
indicate portions (cut regions) to be removed in later cutting the aggregate board
11
.
After the aggregate board
11
is prepared, lower electrodes
25
and first upper electrodes
23
made of gold or silver are provided (T1, T2). As shown in
FIG. 16
, each of the first upper electrodes
23
extends across a cut region
13
. Subsequently, as shown in
FIG. 17
, resistor elements
26
are formed by printing and baking a resistor paste (T3). After each of the resistor elements
26
is covered with an overcoat layer
27
(T4), the resistance is adjusted. Specifically, as shown in
FIG. 18
, a groove
31
for adjusting the resistance is formed in the resistor element
26
by laser trimming (T5). Cuttings generated by the trimming are removed by washing (T6). Then, as shown in
FIG. 19
, second overcoat layers
29
are formed on the first overcoat layers
27
(T7). The second overcoat layers
27
partially cover the first upper electrodes
23
. Subsequently, as shown in
FIG. 20
, second upper electrodes
28
are formed to cover the exposed portions of the first upper electrodes
23
(T8). The second upper electrodes
28
, which are provided as auxiliary electrodes of the first upper electrodes
23
, are formed of a resin material containing silver particles. The second upper electrodes
28
are less malleable than the first upper electrodes
23
. Then, in a first dicing step T9, the aggregate board
11
is cut along cutting lines L
1
shown in
FIG. 21
into intermediate substrates (not shown) in the form of a thin strip. Thereafter, side electrodes
24
are formed on the cut surfaces of the intermediate substrates (T10). The intermediate substrates are cut along cutting lines L
2
(See
FIG. 21
) in a second dicing step T11. Finally, nickel-plating (or solder-plating) is applied to each of the exposed electrodes
24
,
25
,
28
(T12), thereby providing chip resistors
21
(
FIG. 13
) as products.
Although the above-described manufacturing method has good manufacturing efficiency because a plurality of chip resistors can be obtained from a single aggregate board, it has the following problems.
As described above, the first dicing of the aggregate board
11
is performed in the process step T9. At that time, the first upper electrodes
23
which is relatively malleable may be stretched upward due to their contact with a dicing blade. In such a case, as shown in
FIG. 22
, the second upper electrodes
28
formed on the first upper electrodes
23
project upward beyond the upper surface of the second overcoat layer
29
. Such rising of the electrodes is undesirable because it causes various disadvantages. For example, in packaging the resistor
21
, the projecting portion of the second upper electrode
28
may come into contact with a taping apparatus, causing loss of the plating layer formed on the projecting portion. Further, due to the upward projecting of the second upper electrode
28
, the electrode
28
may not be properly connected to the side electrode
24
.
SUMMARY OF THE INVENTION
An object of the present invention, which is conceived under the circumstances described above, is to provide a method of making a chip-type electronic device without rising an electrode.
According to a first aspect of the present invention, there is provided a method of making a chip-type electronic device. Firstly, in this method, a first electrode is formed on an aggregate board. Then, a second electrode overlapping the first electrode is formed. Finally, the aggregate board is cut along a predetermined cutting line. The first electrode is formed as spaced from the cutting line.
Preferably, the aggregate board includes a cut region to be removed in the cutting step, and the second electrode extends over the cut region.
Preferably, the method of the present invention further includes the step of forming a conductive element for connection to the first electrode on the aggregate board. The second electrode is so formed as to overlap both the first electrode and the conductive element.
Preferably, the second electrode is less malleable than the first electrode.
Preferably, the conductive element is a resistor layer. In this case, the method of the present invention further includes the step of adjusting resistance by forming a trimming groove in the resistor layer, and the resistance adjusting step is performed after the second electrode forming step.
According to a second aspect of the present invention, there is provided a chip-type electronic device. The electronic device is manufactured by the above-described manufacturing method.
Other objects, features and advantages of the present invention will become clearer from the description of the preferred embodiment given below.
REFERENCES:
patent: 6153256 (2000-11-01), Kambara et al.
patent: 6242999 (2001-06-01), Nakayama et al.
patent: 10-321421 (1998-12-01), None
Lee Hsien-Ming
Merchant & Gould P.C.
Rohm & Co., Ltd.
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