U.S. patent application number 15/229564 was filed with the patent office on 2017-06-22 for chip resistor.
The applicant listed for this patent is SAMSUNG ELECTRO-MECHANICS CO., LTD.. Invention is credited to Jin Man HAN, Jang Seok YUN.
Application Number | 20170179217 15/229564 |
Document ID | / |
Family ID | 59066378 |
Filed Date | 2017-06-22 |
United States Patent
Application |
20170179217 |
Kind Code |
A1 |
HAN; Jin Man ; et
al. |
June 22, 2017 |
CHIP RESISTOR
Abstract
A chip resistor includes a substrate having first and second
electrodes disposed on one surface thereof to be separated from
each other. A first resistor electrically connects the first
electrode to the second electrode, and a second resistor
electrically connects the first electrode to the second electrode.
When temperatures of the first electrode and the second electrode
are different from each other, thermo electromotive force generated
from the first resistor is less than thermo electromotive force
generated from the second resistor, and a temperature coefficient
of resistivity (TCR) of the second resistor is lower than the TCR
of the first resistor.
Inventors: |
HAN; Jin Man; (Suwon-si,
KR) ; YUN; Jang Seok; (Suwon-si, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SAMSUNG ELECTRO-MECHANICS CO., LTD. |
Suwon-si |
|
KR |
|
|
Family ID: |
59066378 |
Appl. No.: |
15/229564 |
Filed: |
August 5, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 28/20 20130101 |
International
Class: |
H01L 49/02 20060101
H01L049/02 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 18, 2015 |
KR |
10-2015-0181816 |
Claims
1. A chip resistor comprising: a substrate; a first electrode
disposed on a surface of the substrate; a second electrode disposed
on a surface of the substrate to be separated from the first
electrode; a first resistor electrically connecting the first
electrode to the second electrode; and a second resistor
electrically connecting the first electrode to the second
electrode, wherein thermo electromotive force generated from the
first resistor is less than thermo electromotive force generated
from the second resistor when temperatures of the first electrode
and the second electrode are different from each other, and a
temperature coefficient of resistivity (TCR) of the second resistor
is lower than a TCR of the first resistor.
2. The chip resistor of claim 1, wherein the first resistor
includes copper-manganese-tin (Cu--Mn--Sn), and the second resistor
includes copper-nickel (Cu--Ni).
3. The chip resistor of claim 2, wherein a ratio of nickel (Ni)
among copper-nickel (Cu--Ni) is between 40% and 50%.
4. The chip resistor of claim 3, wherein a resistance value of the
first resistor is between 3 m.OMEGA. and 100 m.OMEGA., a resistance
value of the second resistor is between 1 m.OMEGA. and 34 m.OMEGA.,
and the resistance value of the first resistor is between three
times and seven times the resistance value of the second
resistor.
5. The chip resistor of claim 1, wherein only the first resistor
among the first and second resistors has a groove.
6. The chip resistor of claim 5, wherein the groove is formed at an
edge of the first resistor that is disposed opposite to another
edge of the first resistor that is closest the second resistor, and
the groove has an "L" shape.
7. The chip resistor of claim 1, wherein a resistance value of the
second resistor decreases when a temperature of the second resistor
increases from a room temperature.
8. The chip resistor of claim 1, further comprising: a third
electrode disposed on a surface of the substrate to be separated
from the first electrode and the second electrode; and a third
resistor disposed on a surface of the substrate and electrically
connecting the third electrode to the second electrode.
9. The chip resistor of claim 1, further comprising: an upper
surface electrode disposed on an upper surface of at least one of
the first electrode, the second electrode, the first resistor, and
the second resistor; and a protection layer covering an upper
surface of at least one of the first electrode, the second
electrode, the first resistor, the second resistor, and the upper
surface electrode.
10. The chip resistor of claim 1, wherein the substrate has first
and second surfaces, the first resistor is disposed on the first
surface, and the second resistor is disposed on the second
surface.
11. A chip resistor comprising: a substrate; a first electrode
disposed on a surface of the substrate; a second electrode disposed
on a surface of the substrate to be separated from the first
electrode; and a plurality of resistors each disposed on a surface
of the substrate to electrically connect the first electrode and
the second electrode to each other and be electrically connected in
parallel with each other, wherein a first resistor of the plurality
of resistors has a groove, and a second resistor of the plurality
of resistors has an average temperature coefficient of resistivity
(TCR) that is lower than an average TCR of the remaining resistors
of the plurality of resistors.
12. The chip resistor of claim 11, wherein the first resistor
includes copper-manganese-tin (Cu--Mn--Sn), the second resistor
includes copper-nickel (Cu--Ni), and a ratio of nickel (Ni) among
copper-nickel (Cu--Ni) in the second resistor is between 40% and
50%.
13. The chip resistor of claim 12, wherein a total resistance value
of the plurality of resistors is between 1 m.OMEGA. and 10
m.OMEGA., and a resistance value of the first resistor is greater
than a resistance value of each of the remaining resistors of the
plurality of resistors.
14. The chip resistor of claim 11, wherein the plurality of
resistors are disposed on the surface of the substrate such that a
resistor including copper-manganese-tin (Cu--Mn--Sn) and a resistor
including copper-nickel (Cu--Ni) are repeatedly alternately
arranged on the surface.
15. The chip resistor of claim 14, wherein the plurality of
resistors are in direct contact with each other.
16. The chip resistor of claim 11, wherein the first resistor is
disposed between two resistors of the plurality of resistors.
17. A method of forming a chip resistor having a predetermined
resistance value comprising: forming on a substrate first and
second electrodes disposed to be spaced apart from each other;
disposing a first resistor on the substrate to directly contact and
electrically connect the first electrode and the second electrode;
disposing a second resistor on the substrate to electrically
connect the first electrode to the second electrode, wherein a
thermo electromotive force generated from the first resistor is
lower than a thermo electromotive force generated from the second
resistor when temperatures of the first electrode and the second
electrode are different from each other; and trimming the first
resistor having the lower electromotive force to achieve the
predetermined resistance value.
18. The method of claim 17, wherein the trimming the first resistor
comprises forming an L-shaped groove in the first resistor to
achieve the predetermined resistance value.
19. The method of claim 18, wherein the trimming the first resistor
comprises trimming only the first resistor having the lower
electromotive force among the first and second resistors.
20. The method of claim 17, wherein the first resistor is trimmed
to have a resistance value that is between three times and seven
times the resistance value of the second resistor.
21. The method of claim 17, wherein the first and second resistors
are disposed on a same surface of the substrate, and the trimming
of the first resistor comprises trimming an edge of the first
resistor other than an edge of the first resistor disposed closest
to the second resistor.
22. The method of claim 17, further comprising: disposing a third
resistor on the substrate to electrically connect the first
electrode to the second electrode, wherein the first, second, and
third resistors are disposed on a same surface of the substrate,
the first resistor has lower heat dissipation capacity than either
of the second and third resistors, and the first resistor having
the lower heat dissipation capacity is disposed between the second
and third resistors on the same surface of the substrate.
23. The method of claim 22, wherein the first resistor directly
contacts each of the second and third resistors.
24. The method of claim 17, wherein the forming the first and
second electrodes comprises forming the first and second electrodes
to cover respective side surfaces of the substrate adjacent to an
upper surface having the first resistor disposed thereon.
25. The method of claim 17, wherein the disposing the second
resistor comprises disposing the second resistor on a first surface
of the substrate opposite to a second surface having the first
resistor disposed thereon.
26. The method of claim 25, wherein the forming the first and
second electrodes comprises forming the first and second electrodes
to each extend from the first surface to the second surface of the
substrate and to cover respective side surfaces of the substrate
adjacent to the first and second surfaces respectively having the
first resistor disposed thereon.
27. The method of claim 17, further comprising: forming a third
electrode on a same surface of the substrate having the first and
second electrodes, the third electrode being disposed to be spaced
apart from each of the first and second electrodes; and disposing a
third resistor on the substrate to directly contact and
electrically connect the second electrode and the third
electrode.
28. A chip resistor comprising: a substrate; a first electrode
disposed on a surface of the substrate; a second electrode disposed
on a surface of the substrate to be separated from the first
electrode; and a plurality of resistors each disposed on a surface
of the substrate to electrically connect the first electrode and
the second electrode to each other and be electrically connected in
parallel with each other, wherein a first resistor of the plurality
of resistors has a temperature coefficient of resistivity (TCR)
that differs from a TCR of a second resistor of the plurality of
resistors.
29. The chip resistor of claim 28, wherein the first resistor of
the plurality of resistors has a thermo electromotive force that
differs from a thermo electromotive force of the second resistor of
the plurality of resistors when temperatures of the first electrode
and the second electrode are different from each other.
30. The chip resistor of claim 28, wherein the first and second
resistors of the plurality of resistors have TCRs of different
positive and negative polarities respectively.
31. The chip resistor of claim 28, wherein the first resistor of
the plurality of resistors has a TCR that is higher than TCRs of
all other resistors electrically connected in parallel
therewith.
32. The chip resistor of claim 31, wherein the first resistor
having the higher TCR is the only resistor among the plurality of
resistors having a groove formed therein.
33. The chip resistor of claim 31, wherein the first resistor
having the higher TCR is disposed between the second resistor and a
third resistor of the plurality of resistors on a surface of the
substrate.
34. The chip resistor of claim 33, wherein the first resistor
having the higher TCR contacts the second and third resistors on
opposite sides thereof.
35. The chip resistor of claim 33, wherein the first resistor
disposed between the second and third resistors is the only
resistor among the first, second, and third resistors having a
groove formed therein.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the priority and benefit of Korean
Patent Application No. 10-2015-0181816, filed on Dec. 18, 2015 with
the Korean Intellectual Property Office, the disclosure of which is
incorporated herein by reference.
BACKGROUND
[0002] The present disclosure relates to a chip resistor.
[0003] Recently, as a demand for miniaturization and lightness of
electronic devices has gradually increased, a chip-shaped resistor
has been widely used to increase wiring density on a circuit
board.
[0004] As required power from the electronic device is increased
and a demand for a chip resistor for current detection in a circuit
is increased, a chip resistor having high precision while having a
low resistance value is required. However, the chip resistor
typically has characteristics resulting in decreased precision as
the resistance value is decreased.
SUMMARY
[0005] An aspect of the present disclosure provides a chip resistor
having high precision while having a low resistance value.
[0006] According to an exemplary embodiment, a chip resistor may
include a substrate, a first electrode disposed on a surface of the
substrate, a second electrode disposed on a surface of the
substrate to be separated from the first electrode, a first
resistor electrically connecting the first electrode to the second
electrode, and a second resistor electrically connecting the first
electrode to the second electrode. Thermo electromotive force
generated from the first resistor is less than thermo electromotive
force generated from the second resistor when temperatures of the
first electrode and the second electrode are different from each
other, and a temperature coefficient of resistivity (TCR) of the
second resistor is lower than the TCR of the first resistor.
[0007] According to another exemplary embodiment, a chip resistor
may include a substrate, a first electrode disposed on a surface of
the substrate, a second electrode disposed on a surface of the
substrate to be separated from the first electrode, and a plurality
of resistors each disposed on a surface of the substrate to
electrically connect the first electrode and the second electrode
to each other and be electrically connected in parallel with each
other. A first resistor of the plurality of resistors has a groove,
and a second resistor of the plurality of resistors has an average
temperature coefficient of resistivity (TCR) that is lower than an
average TCR of the remaining resistors of the plurality of
resistors.
[0008] According to a further exemplary embodiment, a method of
forming a chip resistor having a predetermined resistance value
includes forming on a substrate first and second electrodes
disposed to be spaced apart from each other. A first resistor is
disposed on the substrate to directly contact and electrically
connect the first electrode and the second electrode. A second
resistor is disposed on the substrate to electrically connect the
first electrode to the second electrode, and a thermo electromotive
force generated from the first resistor is lower than a thermo
electromotive force generated from the second resistor when
temperatures of the first electrode and the second electrode are
different from each other. Finally, the first resistor having the
lower electromotive force is trimmed to achieve the predetermined
resistance value.
[0009] According to another exemplary embodiment, a chip resistor
includes a substrate, a first electrode disposed on a surface of
the substrate, a second electrode disposed on a surface of the
substrate to be separated from the first electrode, and a plurality
of resistors each disposed on a surface of the substrate to
electrically connect the first electrode and the second electrode
to each other and be electrically connected in parallel with each
other. Additionally, a first resistor of the plurality of resistors
has a temperature coefficient of resistivity (TCR) that differs
from a TCR of a second resistor of the plurality of resistors.
BRIEF DESCRIPTION OF DRAWINGS
[0010] The above and other aspects, features, and advantages of the
present disclosure will be more clearly understood from the
following detailed description taken in conjunction with the
accompanying drawings, in which:
[0011] FIG. 1 is a view illustrating a chip resistor according to
an exemplary embodiment;
[0012] FIG. 2 is a view illustrating a groove formed in a resistor
of the chip resistor according to an exemplary embodiment;
[0013] FIG. 3 is a view illustrating a layout of a resistor of a
chip resistor according to an exemplary embodiment;
[0014] FIG. 4A is a rear view illustrating a layout of a resistor
of a chip resistor according to an exemplary embodiment;
[0015] FIG. 4B is a perspective view of the chip resistor
illustrated in FIG. 4A;
[0016] FIG. 5 is a view illustrating a side surface of a chip
resistor according to an exemplary embodiment;
[0017] FIG. 6 is a view illustrating a side surface of a chip
resistor having resistors disposed on opposing surfaces thereof
according to an exemplary embodiment;
[0018] FIG. 7 is a view illustrating a three-terminal form of a
chip resistor according to an exemplary embodiment;
[0019] FIG. 8 is a graph illustrating a temperature coefficient of
resistivity (TCR) and resistance according to a ratio of nickel
(Ni) in a second resistor;
[0020] FIG. 9 is a graph illustrating the TCR of first and second
resistors; and
[0021] FIG. 10 is a flowchart illustrating a method of
manufacturing a chip resistor according to an exemplary
embodiment.
DETAILED DESCRIPTION
[0022] Hereinafter, embodiments of the present disclosure will be
described as follows with reference to the attached drawings.
[0023] The present disclosure may, however, be exemplified in many
different forms and should not be construed as being limited to the
specific embodiments set forth herein. Rather, these embodiments
are provided so that this disclosure will be thorough and complete,
and will fully convey the scope of the disclosure to those skilled
in the art.
[0024] Throughout the specification, it will be understood that
when an element, such as a layer, region, or wafer (substrate) is
referred to as being "on," "connected to," or "coupled to" another
element, it can be directly "on," "connected to," or "coupled to"
the other element or other elements intervening therebetween may be
present. In contrast, when an element is referred to as being
"directly on," "directly connected to," or "directly coupled to"
another element, there may be no elements or layers intervening
therebetween. Like numerals refer to like elements throughout. As
used herein, the term "and/or" includes any and all combinations of
one or more of the associated listed items.
[0025] It will be apparent that though the terms first, second,
third, etc. may be used herein to describe various members,
components, regions, layers, and/or sections, these members,
components, regions, layers, and/or sections should not be limited
by these terms. These terms are only used to distinguish one
member, component, region, layer, or section from another member,
component, region, layer, or section. Thus, a first member,
component, region, layer, or section discussed below could be
termed a second member, component, region, layer, or section
without departing from the teachings of the exemplary
embodiments.
[0026] Spatially relative terms, such as "above," "upper," "below,"
"lower," and the like, may be used herein for ease of description
to describe one element's positional relationship relative to one
or more other elements as shown in the figures. It will be
understood that the spatially relative terms are intended to
encompass different orientations of the device in use or operation
in addition to the orientation depicted in the figures. For
example, if the device in the figures is turned over, elements
described as "above" or "upper" relative to other elements would
then be oriented "below" or "lower" relative to the other elements
or features. Thus, the term "above" can encompass both the above
and below orientations depending on a particular direction of the
devices, elements, or figures. The device may be otherwise oriented
(rotated 90 degrees or at other orientations) and the spatially
relative descriptors used herein may be interpreted
accordingly.
[0027] The terminology used herein describes particular
illustrative embodiments only, and the present disclosure is not
limited thereby. As used herein, the singular forms "a," "an," and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising," when used in this
specification, specify the presence of stated features, integers,
steps, operations, members, elements, and/or groups, but do not
preclude the presence or addition of one or more other features,
integers, steps, operations, members, elements, and/or groups.
[0028] Hereinafter, embodiments of the present disclosure will be
described with reference to schematic views illustrating
embodiments. In the drawings, components having ideal shapes are
shown. However, variations from these ideal shapes, for example due
to variability in manufacturing techniques and/or tolerances, also
fall within the scope of the disclosure. Thus, embodiments of the
present disclosure should not be construed as being limited to the
particular shapes of regions shown herein, but should more
generally be understood to include changes in shape resulting from
manufacturing methods and processes. The following embodiments may
also be constituted by one or a combination thereof.
[0029] The present disclosure describes a variety of
configurations, and only illustrative configurations are shown
herein. However, the disclosure is not limited to the particular
illustrative configurations presented herein, but extends to other
similar/analogous configurations as well.
[0030] FIG. 1 is a view illustrating a chip resistor according to
an exemplary embodiment.
[0031] Referring to FIG. 1, a chip resistor according to an
exemplary embodiment includes a substrate 110, a first electrode
121, a second electrode 122, a first resistor 131, and a second
resistor 132.
[0032] The substrate 110 may provide a space for mounting the
electrodes and the resistors. For example, the substrate 110 may be
an insulating substrate formed of a ceramic material. The ceramic
material may be alumina (Al.sub.2O.sub.3), but is not particularly
limited as long as the material has excellent insulation, heat
dissipation, and adhesion properties with the resistor.
[0033] The first electrode 121 may be disposed on one surface of
the substrate 110.
[0034] The second electrode 122 may be disposed to be spaced apart
from the first electrode 121 on the one surface of the substrate
110.
[0035] For example, the first and second electrodes 121 and 122 may
be implemented to have a low resistance value, and may be formed
using copper and/or a copper alloy.
[0036] The first resistor 131 and the second resistor 132 may each
electrically connect between the first electrode 121 and the second
electrode 122 on the one surface of the substrate 110. That is, the
first resistor 131 and the second resistor 132 may be connected in
parallel with each other between the first and second electrodes
121 and 122.
[0037] For example, an adhesive for increasing adhesion when the
first and second resistors 131 and 132 are sintered may be attached
between the first resistor 131 and the substrate 110 and between
the second resistor 132 and the substrate 110. For example, the
adhesive may be a resin material such as an epoxy, or the like, and
may be a material having excellent heat dissipation properties
including copper (Cu), nickel (Ni), or copper-nickel (Cu--Ni).
[0038] Here, the first and second resistors 131 and 132 may be
alloyed by an ionic diffusion bonding when sintered and may be
coupled to the substrate 110.
[0039] In addition, thermal characteristics of the first resistor
131 and thermal characteristics of the second resistor 132 may be
different from each other.
[0040] That is, thermo electromotive force occurring from the first
resistor 131 at a predetermined temperature may be less than the
thermo electromotive force occurring from the second resistor 132
at the predetermined temperature. Here, thermo electromotive force
refers to electromotive force occurring when temperatures of two
connection points of the material have different values. Therefore,
a predetermined temperature condition may include a temperature
difference between specific points in the resistor. Here, the
specific points may each be a contact point of the first or second
electrode 121 or 122 of the first resistor 131, but are not
particularly limited.
[0041] A total resistance value of the first and second resistors
131 and 132 may be finely adjusted by a trimming operation for the
first resistor 131. Here, the trimming operation refers to an
operation of adjusting a resistance value of the resistor by
forming a groove in the resistor and measuring the resistance value
of the resistor at the same time, and stopping the forming of the
groove when the resistance value reaches a target resistance value.
Accordingly, precision of the chip resistor's resistance value
according to an exemplary embodiment may be increased.
[0042] Here, the resistor which is subjected to the trimming
operation is preferably made of a material having low thermo
electromotive force occurring in a predetermined thermal condition.
In detail, the trimming operation may typically emit heat while
forming the groove. The heat emitted from the resistor may cause
thermo electromotive force in the resistor. In turn, the thermo
electromotive force may cause a distortion during a process of
measuring the resistance value of the resistor.
[0043] Accordingly, as the thermo electromotive force occurring in
the predetermined thermal condition of the first resistor 131 is
low, precision of the chip resistor according to an exemplary
embodiment may be increased.
[0044] For example, the first resistor 131 may include
copper-manganese-tin (Cu--Mn--Sn) for achieving desired thermo
electromotive force characteristics.
[0045] However, in the resistor having the low thermo electromotive
force occurring in the predetermined thermal condition, a
temperature coefficient of resistivity (TCR) that characterizes the
variation of the resistance value depending on a temperature change
may be high. That is, the TCR of the first resistor 131 may be
high.
[0046] If a total TCR of the first and second resistors 131 and 132
is high, precision of the first and second resistors 131 and 132
may be decreased. An effect of the TCR on the precision may be
larger, as the resistance value of the first and second resistors
131 and 132 is low. Therefore, in a case in which the resistance
value of the first and second resistors 131 and 132 is 100 m.OMEGA.
or less, the total TCR of the first and second resistors 131 and
132 may need to be decreased.
[0047] The second resistor 132 may not be the resistor which is
subjected to the trimming operation. In addition, even though the
trimming operation is not performed for the second resistor 132, a
final total resistance value may be adjusted later by the trimming
operation for the first resistor 131. Therefore, the second
resistor 132 may not be formed so as to have the low thermo
electromotive force occurring in the predetermined thermal
condition. In the resistor, thermo electromotive force
characteristics and TCR characteristics may have a trade-off
relationship.
[0048] Therefore, the TCR of the second resistor 132 may be lower
than that of the first resistor 131. Accordingly, a total TCR of
the first and second resistors 131 and 132 may be lower than the
TCR of the first resistor 131.
[0049] For example, the second resistor 132 may include
copper-nickel (Cu--Ni). That is, the second resistor 132 may
decrease the TCR by including materials having low TCR such as
constantan, manganin, nichrome, and the like. Therefore, the second
resistor 132 may include a material such as copper-nickel-manganese
(Cu--Ni--Mn) or nickel-chromium (Ni--Cr).
[0050] Accordingly, the chip resistor according to an exemplary
embodiment may be implemented at high precision while having a low
resistance value.
[0051] FIG. 2 is a view illustrating a groove formed in a resistor
of the chip resistor according to an exemplary embodiment.
[0052] Referring to FIG. 2, a chip resistor according to an
exemplary embodiment may include a substrate 210, a first electrode
221, a second electrode 222, a first resistor 231, and a second
resistor 232.
[0053] The first resistor 231 may have a groove therein. For
example, the groove may be formed by a laser. The laser may form
the groove extending from an edge of the first resistor 231. In
this case, the laser may extend a length of the groove while being
slowly moved toward the center of the first resistor 231.
[0054] As the length of the groove is increased, a resistance value
of the first resistor 231 may be increased. When the first resistor
231 includes three resistors that are connected in series with each
other, a cross section area of a middle resistor may be decreased
by the formation of the groove. Here, as the cross section area of
the middle resistor is decreased, a resistance value of the middle
resistor may be increased. As a result, a total of resistance value
of the resistor may be increased.
[0055] In a case in which the resistance value of the first
resistor 231 reaches a target resistance value, the laser may
change a movement direction thereof. A rate of increase of the
resistance value of the first resistor 231 according to the
increase in the length of the groove after the change in the
movement direction of the laser may be lower than a rate of
increase of the resistance value of the first resistor 231
according to the increase in the length of the groove before the
change in the movement direction of the laser. Therefore, after the
movement direction of the laser is changed, the resistance value of
the first resistor 231 may be more precisely adjusted.
[0056] Here, the groove may have an "L" shape, as shown in FIG. 2.
In addition, in order to reduce an effect on the second resistor
232 during a process of forming the groove, the groove may be
formed in an edge of the first resistor that is opposite to another
edge of the first resistor that is closest to (and/or faces) the
second resistor.
[0057] FIG. 3 is a view illustrating a layout of a resistor of a
chip resistor according to an exemplary embodiment.
[0058] Referring to FIG. 3, a chip resistor according to an
exemplary embodiment may include a substrate 310, a first electrode
321, a second electrode 322, a first resistor 331, and second
resistors 332a and 332b.
[0059] As the TCR is low, the resistor may typically have excellent
heat dissipation properties. Therefore, the heat dissipation
properties of the second resistors 332a and 332b may be higher than
that of the first resistor 331.
[0060] Therefore, the first resistor 331 may be disposed between
the second resistors 332a and 332b. Accordingly, heat generated
when a current flows in the first resistor 331 may be efficiently
diffused through the second resistors 332a and 332b.
[0061] FIG. 4A is a rear view illustrating a layout of a resistor
of a chip resistor according to an exemplary embodiment.
[0062] FIG. 4B is a perspective view of the chip resistor
illustrated in FIG. 4A.
[0063] Referring to FIGS. 4A and 4B, a chip resistor according to
an exemplary embodiment may include a substrate 410, a first
electrode 421, a second electrode 422, a first resistor 431, and
second resistors 432a and 432b.
[0064] The first resistor 431 and the second resistors 432a and
432b may be implemented by a thin film. Therefore, as widths
(measured in an x direction) of the first resistor 431 and the
second resistors 432a and 432b are long or lengths (measured in a y
direction) thereof are short, resistance values of the first
resistor 431 and the second resistors 432a and 432b may be
decreased.
[0065] In order to increase the widths (measured in the x
direction) of the first resistor 431 and the second resistors 432a
and 432b, the first resistor 431 and the second resistors 432a and
432b may be in contact with each other. Accordingly, the chip
resistor according to an exemplary embodiment may be easily
implemented to have the resistance value of 100 m.OMEGA. or
less.
[0066] Here, in order to efficiently diffuse heat generated by a
current flowing in the first resistor 431 and the second resistors
432a and 432b, the first resistor 431 and the second resistors 432a
and 432b may be alternately and repeatedly arranged.
[0067] Meanwhile, the first and second electrodes 421 and 422 may
be formed to cover side surfaces of the substrate 410. A
description thereof will be provided when a bottom surface
electrode is described with reference to FIG. 5.
[0068] FIG. 5 is a view illustrating a side surface of a chip
resistor according to an exemplary embodiment.
[0069] Referring to FIG. 5, a chip resistor according to an
exemplary embodiment may include a substrate 510, a first electrode
521, a second electrode 522, a resistor 530, a first upper surface
electrode 541, a second upper surface electrode 542, a protection
layer 550, a first bottom surface electrode 561, a second bottom
surface electrode 562, a first metal cover 571, and a second metal
cover 572.
[0070] The first and second upper surface electrodes 541 and 542
may be disposed on an upper surface of at least one of the first
electrode 521, the second electrode 522, and the resistor 530. In a
case in which the first and second upper surface electrodes 541 and
542 are disposed on the first and second electrodes 521 and 522,
respectively, the first and second upper surface electrodes 541 and
542 may serve as wirings for receiving a current from the outside
or providing the current to the outside. In a case in which the
first and second upper surface electrodes 541 and 542 are disposed
on the resistor 530, the first and second upper surface electrodes
541 and 542 may efficiently emit heat generated from the resistor
530 using high thermal conductivity which is a property of a
metal.
[0071] The protection layer 550 may cover an upper surface of at
least one of the first electrode 521, the second electrode 522, the
resistor 530, the first upper surface electrode 541, and the second
upper surface electrode 542. For example, the protection layer 550
may be formed of an epoxy, a phenol resin, a glass material, or the
like to protect the chip resistor from external physical
impact.
[0072] The first and second bottom surface electrodes 561 and 562
may assist a layout of the first and second electrodes 521 and 522,
respectively. For example, the first and second metal covers 571
and 572 having a shape of U may be inserted into or around both
side surfaces of the substrate 510. The first and second metal
covers 571 and 572 may press the first and second electrodes 521
and 522 so as to be fixed, and may serve as connecting electrodes
providing electrical connections between the top and bottom
surfaces of the substrate 510. Here, the first and second bottom
surface electrodes 561 and 562 may be formed on the other surface
of the substrate 510 in advance so as to be pressed by the first
and second metal covers 571 and 572. Accordingly, the first and
second electrodes 521 and 522 may be stably fixed. In addition, as
a total area of the first and second bottom surface electrodes 561
and 562 and the first and second electrodes 521 and 522 is
increased, a resistance value of the first and second electrodes
may be further decreased. Accordingly, a total resistance value of
the chip resistor according to an exemplary embodiment may be
further decreased.
[0073] FIG. 6 is a view illustrating a side surface of a chip
resistor having resistors disposed on opposing surfaces thereof
according to an exemplary embodiment.
[0074] Referring to FIG. 6, a chip resistor according to an
exemplary embodiment may include the substrate 510, the first
electrode 521, the second electrode 522, a first resistor 531, a
second resistor 532, the first upper surface electrode 541, the
second upper surface electrode 542, a first protection layer 551, a
second protection layer 552, the first bottom surface electrode
561, the second bottom surface electrode 562, the first metal cover
571, and the second metal cover 572.
[0075] The first resistor 531 may be disposed on one surface of the
substrate 510 to be directly connected to the first and second
electrodes 521 and 522. The first protection layer 551 may be
formed on one surface of the first resistor 531.
[0076] The second resistor 532 may be disposed on another surface
of the substrate 510 (e.g., another surface that is opposite to the
one surface having the first resistor 531 thereon) to be directly
connected to the first and second bottom surface electrodes 561 and
562. The second protection layer 552 may be formed on one surface
of the second resistor 532.
[0077] The first electrode 521 and the first bottom surface
electrode 561 may be electrically connected to each other through
the first metal cover 571, and the second electrode 522 and the
second bottom surface electrode 562 may be electrically connected
to each other through the second metal cover 572. Accordingly, the
first resistor 531 disposed on one surface of the substrate 510 and
the second resistor 532 disposed on the other surface of the
substrate 510 may be electrically coupled in parallel with each
other.
[0078] As the first resistor 531 and the second resistor 532 are
disposed on different surfaces, a width of the substrate 510 may be
decreased. In addition, when the first and second resistors 531 and
532 including different components are formed, a net effect of each
resistor's operational characteristics on the chip resistor may be
decreased.
[0079] FIG. 7 is a view illustrating a three-terminal form of a
chip resistor according to an exemplary embodiment.
[0080] Referring to FIG. 7, a chip resistor according to an
exemplary embodiment may include a substrate 610, a first electrode
621, a second electrode 622, a third electrode 623, a first
resistor 631, a second resistor 632, and a third resistor 633.
[0081] The third electrode 623 may be disposed to be spaced apart
from the first and second electrodes 621 and 622 on one surface of
the substrate 610. For example, the third electrode 623 may be
formed of the same material, form or shape, and method as those of
the first and second electrodes 621 and 622.
[0082] The third resistor 633 may electrically connect between the
third electrode 623 and the second electrode 622.
[0083] The third electrode 623 may be electrically connected to the
first electrode 621 from the outside to serve as a preliminary
electrode for the first electrode 621. In a case in which the first
electrode 621 is disconnected from the outside by a defect
occurring during a process of manufacturing the chip resistor or
impact occurring during a process of using the chip resistor, the
third electrode 623 may instead perform a role of the first
electrode 621.
[0084] Therefore, the third resistor 633 may also be implemented by
a plurality of resistors having different thermal characteristics
in order to have the same characteristics as the first and second
resistors 631 and 632.
[0085] FIG. 8 is a graph illustrating a temperature coefficient of
resistivity (TCR) and resistance according to a ratio of nickel
(Ni) in a second resistor.
[0086] Referring to FIG. 8, numbers following CN of a horizontal
axis denote numbers obtained by multiplying a ratio of nickel (Ni)
of copper-nickel (Cu--Ni) by 100. In addition, the TCR of a
vertical axis denotes a temperature coefficient of resistivity
using a unit of ppm/temperature.
[0087] The resistor, which has a TCR in the range of thousands of
ppm/temperature, may have characteristics that when a temperature
thereof is increased as much as 1.quadrature., a resistance value
thereof is increased as much as a few .OMEGA.. Here, in a case in
which the resistance value of the resistor is tens of .OMEGA., the
resistor may have characteristics that the resistance value changes
by about 10% even though the temperature is changed as much as only
1.quadrature.. Therefore, in order for the chip resistor having the
resistance value of 100 m.OMEGA. or less to have a precise
resistance value, an absolute value of a total of TCR may need to
be decreased.
[0088] The chip resistor according to an exemplary embodiment may
have a structure in which a resistor capable of performing a
trimming operation and a resistor including copper-nickel (Cu--Ni)
are connected in parallel with each other. Here, it may be
difficult to adjust the TCR of the resistor capable of performing
the trimming operation. Therefore, by adjusting the TCR of the
resistor including copper-nickel (Cu--Ni), a total TCR of the chip
resistor may be decreased.
[0089] It may be seen from the graph of FIG. 8 that the resistor
including copper-nickel (Cu--Ni) has the lowest TCR when a ratio of
nickel (Ni) of copper-nickel (Cu--Ni) is 40% or more and 50% or
less (e.g., in a range between 40% and 50%). Therefore, the chip
resistor according to an exemplary embodiment includes the resistor
having the ratio of nickel (Ni) that is 40% or more and 50% or less
while including copper-nickel (Cu--Ni), whereby the total TCR may
be significantly decreased.
[0090] Meanwhile, a negative TCR value indicates that when the
temperature is increased, the resistance value is decreased. That
is, the resistor including copper-nickel (Cu--Ni) may have
characteristics that when the ratio of nickel (Ni) of copper-nickel
(Cu--Ni) is in the range of 40% to 50% and the temperature is
increased, the resistance value is decreased. Accordingly, by
combining a resistor having a positive TCR characteristic and a
resistor having a negative TCR characteristic, the TCR
characteristics may offset each other to provide an overall zero
(or near-zero) TCR characteristic. Note that the evaluation of
whether a resistor has a positive or negative TCR is performed at
room temperature (e.g., at a temperature in a range of
10-35.degree. C.)
[0091] The chip resistor according to an exemplary embodiment may
have a structure in which the first resistor has good
thermo-electromotive force but has bad TCR characteristics and is
connected in parallel with the second resistor that includes
copper-nickel (Cu--Ni) in which the ratio of nickel (Ni) is 45% and
has good TCR characteristics. A total resistance value and a total
TCR of the chip resistor is determined according to the resistance
value of the first resistor and the resistance value of the second
resistor, and the total resistance value may be listed in the
following Table 1.
TABLE-US-00001 TABLE 1 20.degree. C. 125.degree. C. -55.degree. C.
20.degree. C. to -55.degree. C. 20.degree. C. a total a total a
total 125.degree. C. to 20.degree. C. Classification Material Only
R of R of R of R TCR TCR Case1 Resistor 1 8 4 m.OMEGA. 4.1 m.OMEGA.
3.92 m.OMEGA. 237 ppm/.degree. C. 259 ppm/.degree. C. Resistor 2 8
Case2 Resistor 1 12 4 m.OMEGA. 4.05 m.OMEGA. 3.96 m.OMEGA. 122
ppm/.degree. C. 142 ppm/.degree. C. Resistor 2 6 Case3 Resistor 1
15 3.75 m.OMEGA. 3.78 m.OMEGA. 3.73 m.OMEGA. 66 ppm/.degree. C. 82
ppm/.degree. C. Resistor 2 5 Case4 Resistor 1 5 3.75 m.OMEGA. 3.91
m.OMEGA. 3.63 m.OMEGA. 415 ppm/.degree. C. 432 ppm/.degree. C.
Resistor 2 15
[0092] In Table 1, R denotes a resistance value using a unit of
.OMEGA., and TCR denotes a temperature coefficient of resistivity
of a unit of ppm/temperature (e.g., ppm/.degree. C.).
[0093] FIG. 9 is a graph illustrating the TCR of first and second
resistors.
[0094] FIG. 9 illustrates in graph-form the TCR results shown in
Table 1. Referring to FIG. 9, it may be seen that the chip resistor
of Case 3 has the best TCR characteristics (e.g., the lowest TCR
values).
[0095] In accordance with Table 1, when the resistance value of the
second resistor is lower than the resistance value of the first
resistor, TCR characteristics of the chip resistor may be
better.
[0096] A reciprocal number of a total of resistance value of the
chip resistor may be calculated by adding a reciprocal number of
the resistance value of the first resistor to a reciprocal number
of the resistance value of the second resistor. Accordingly, as the
resistance value of the second resistor is lower than the
resistance value of the first resistor, an effect on the total
resistance value resulting from a change in the resistance value of
the second resistor may be greater than an effect on the total
resistance value resulting from a change in the resistance value of
the first resistor. Therefore, as the resistance value of the
second resistor is lower than the resistance value of the first
resistor, a total TCR of the chip resistor may be closer to the TCR
of the second resistor rather than the TCR of the first
resistor.
[0097] For example, in the chip resistor of Case 1, the resistance
value of the first resistor may be about equal to (e.g., equal to
one time of) the resistance value of the second resistor. Here, a
ratio of the TCR of the second resistor to the total TCR of the
chip resistor may be about 50%.
[0098] In the chip resistor of Case 2, the resistance value of the
first resistor may be about two times the resistance value of the
second resistor. Here, a ratio of the TCR of the second resistor to
the total TCR of the chip resistor may be about 67%.
[0099] Further, in the chip resistor of Case 3, the resistance
value of the first resistor may be about three times the resistance
value of the second resistor. Here, a ratio of the TCR of the
second resistor to the total TCR of the chip resistor may be about
75%.
[0100] Referring to a progression of the ratio of the TCR of the
second resistor to the total TCR of the chip resistor, in a case in
which the resistance value of the second resistor is about five
times the resistance value of the first resistor, it may be
inferred that the total of TCR of the chip resistor reaches zero
(0).
[0101] Therefore, in the chip resistor according to an exemplary
embodiment, the resistance value of the second resistor may be
designed to be three times or more and seven times or less (e.g.,
in a range of three to seven times) of the resistance value of the
first resistor. Accordingly, the change in the resistance value
depending on the temperature change of the chip resistor may be
significantly decreased.
[0102] FIG. 10 is a flowchart illustrating a method of
manufacturing a chip resistor according to an exemplary
embodiment.
[0103] Referring to FIG. 10, a chip resistor according to an
exemplary embodiment may be manufactured by an operation S10 of
forming one or more electrodes (e.g., electrodes 221 and 222), an
operation S20 of forming a first resistor (e.g., 231), an operation
S30 of forming a second resistor (e.g., 232), and an operation S40
of trimming the first resistor.
[0104] The operation S10 of forming the electrode refers to an
operation of painting, spraying, or printing a paste in an ink
state on a substrate. The printing may be performed by a screen
method. Accordingly, a thickness of the one or more electrode(s)
may be precisely controlled.
[0105] The operation S20 of forming the first resistor refers to an
operation of printing a resistor having good thermo electromotive
force characteristics on the substrate.
[0106] The operation S30 of forming the second resistor refers to
an operation of printing a resistor having good TCR characteristics
on the substrate. A process from the operation S10 of forming the
electrode to the operation S30 of forming the second resistor may
be performed by a thick film process. Accordingly, a sintering of
the electrode and the resistor may be performed in a reduction
atmosphere at a temperature between 800.degree. C. and 1400.degree.
C. Here, recrystallization of the resistor and the electrode may be
performed, and a grain growth thereof may occur. In this case,
electrical conductivity between the resistor and the electrode may
be improved. Accordingly, the chip resistor according to an
exemplary embodiment may be implemented to have a low resistance
value of 100 m.OMEGA. or less.
[0107] The printing and the sintering of the paste may be repeated.
Accordingly, initial resistance values of the electrode and the
resistor may be optimized.
[0108] Further, the resistance value of the chip resistor may be
adjusted by a method such as laser dicing, laser-etching, sand
blasting, or the like after forming the electrode.
[0109] In the operation S40 of trimming the first resistor, a
groove may be formed from an edge of the first resistor using a
laser. In this case, a measurement of a total resistance value of
the chip resistor may be performed at the same time as the trimming
is performed. A length of the groove may be extended until the
total resistance value of the chip resistor reaches a target
resistance value.
[0110] As set forth above, according to the exemplary embodiments,
the chip resistor may have high precision while having a low
resistance value.
[0111] While exemplary embodiments have been shown and described
above, it will be apparent to those skilled in the art that
modifications and variations could be made without departing from
the scope of the present invention as defined by the appended
claims.
* * * * *