U.S. patent application number 10/417180 was filed with the patent office on 2003-11-20 for current detection equipment and semiconductor device.
This patent application is currently assigned to KABUSHIKI KAISHA TOSHIBA. Invention is credited to Domon, Tomokazu, Kodani, Kazuya, Omura, Ichiro.
Application Number | 20030214313 10/417180 |
Document ID | / |
Family ID | 29416591 |
Filed Date | 2003-11-20 |
United States Patent
Application |
20030214313 |
Kind Code |
A1 |
Omura, Ichiro ; et
al. |
November 20, 2003 |
Current detection equipment and semiconductor device
Abstract
A current detection equipment comprises a first coil and a
second coil connected in series with the first coil. The current
detection equipment is capable of detecting a current flowing
through an object which is provided between the first and second
coils or provided in a vicinity of the first or second coil. Each
of the first and second coils having first conductive patterns
provided on a surface of a substrate, a second conductive patterns
provided on a back of the substrate and connecting parts which
connect the first and second conductive patterns. A semiconductor
device including the current detection equipment to measure the
current flowing in a semiconductor element is also proposed.
Inventors: |
Omura, Ichiro; (Kanagawa,
JP) ; Domon, Tomokazu; (Kanagawa, JP) ;
Kodani, Kazuya; (Kanagawa, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
KABUSHIKI KAISHA TOSHIBA
Tokyo
JP
JP
|
Family ID: |
29416591 |
Appl. No.: |
10/417180 |
Filed: |
April 17, 2003 |
Current U.S.
Class: |
324/713 |
Current CPC
Class: |
H01L 2924/00011
20130101; G01R 31/2884 20130101; H01L 2924/01015 20130101; H01L
2924/13091 20130101; G01R 15/181 20130101; H01L 2224/0603 20130101;
H01L 2924/13055 20130101; H01L 2924/00011 20130101; H01L 2924/00011
20130101; H01L 2224/49111 20130101; G01R 31/2644 20130101; H01L
2924/00011 20130101; H01L 2224/49113 20130101; H01L 2924/13091
20130101; G01R 19/0092 20130101; H01L 2924/13055 20130101; H01L
2224/48227 20130101; H01L 2924/00 20130101; H01L 2924/01005
20130101; H01L 2924/01033 20130101; H01L 2924/00 20130101 |
Class at
Publication: |
324/713 |
International
Class: |
G01R 027/08 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 18, 2002 |
JP |
2002-115969 |
Claims
What is claimed is:
1. A current detection equipment comprising: a first coil; and a
second coil connected in series with the first coil, the current
detection equipment being capable of detecting a current flowing
through an object which is provided between the first and second
coils or provided in a vicinity of the first or second coil, and
each of the first and second coils having first conductive patterns
provided on a surface of a substrate, a second conductive patterns
provided on a back of the substrate and connecting parts which
connect the first and second conductive patterns.
2. A current detection equipment according to claim 1, wherein the
first and second coils are connected so that a voltage induced by a
magnetic flux generated by the current flowing through the object
in the first coil and a voltage induced by the magnetic flux
generated by the current flowing through the object in the second
coil are added.
3. A current detection equipment comprising: a substrate having a
notch or a hole; and a first and a second coils provided on
opposite sides of the notch or the hole, each of the first and
second coils having first conductive patterns provided on a surface
of the substrate, a second conductive patterns provided on a back
of the substrate and connecting parts which connect the first and
second conductive patterns.
4. A current detection equipment according to claim 3, wherein the
first and second coils are connected in series.
5. A current detection equipment according to claim 3, wherein the
first and second coils are connected so that a voltage induced by a
magnetic flux generated by the current flowing through the object
in the first coil and a voltage induced by the magnetic flux
generated by the current flowing through the object in the second
coil are added.
6. A current detection equipment according to claim 3, wherein each
of the connecting parts has a conductor which penetrates the
substrate.
7. A current detection equipment according to claim 3, wherein each
of the connecting parts has a conductive pattern provided on a side
surface of the substrate.
8. A current detection equipment according to claim 4, wherein at
least a part of a wiring which connects the first and second coils
extends inside the substrate.
9. A current detection equipment according to claim 4, further
comprising a resistance connected in parallel to the first and
second coils.
10. A current detection equipment according to claim 3, further
comprising a integration circuit connected to the first and second
coils.
11. A current detection equipment comprising: a first substrate
having a first coil; a second substrate having a second coil; and a
spacer provided between the first and second substrates, the first
coil having first conductive patterns provided on a surface of the
first substrate, a second conductive patterns provided on a back of
the first substrate and connecting parts which connect the first
and second conductive patterns, the second coil having first
conductive patterns provided on a surface of the second substrate,
a second conductive patterns provided on a back of the second
substrate and connecting parts which connect the first and second
conductive patterns.
12. A current detection equipment according to claim 11, wherein
the first and second coils are connected in series.
13. A current detection equipment according to claim 11, wherein
the first and second coils are connected so that a voltage induced
by a magnetic flux generated by the current flowing through the
object in the first coil and a voltage induced by the magnetic flux
generated by the current flowing through the object in the second
coil are added.
14. A current detection equipment according to claim 11, wherein
each of the connecting parts has a conductor which penetrates the
substrate.
15. A current detection equipment according to claim 11, wherein
each of the connecting parts has a conductive pattern provided on a
side surface of the substrate.
16. A current detection equipment according to claim 12, wherein at
least a part of a wiring which connects the first and second coils
extends inside the substrate.
17. A current detection equipment according to claim 12, further
comprising a resistance connected in parallel to the first and
second coils.
18. A current detection equipment according to claim 11, further
comprising a integration circuit connected to the first and second
coils.
19. A semiconductor device comprising: a semiconductor element; and
a current detection equipment including a substrate having a notch
or a hole; and a first and a second coils provided on opposite
sides of the notch or the hole, each of the first and second coils
having first conductive patterns provided on a surface of the
substrate, a second conductive patterns provided on a back of the
substrate and connecting parts which connect the first and second
conductive patterns, and at least a part of a current flowing in
the semiconductor element being detected by the current detection
equipment.
20. A semiconductor device according to claim 19, wherein a bonding
wire is connected to the semiconductor element, and the first and
second coils are provided to sandwich the bonding wire.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based upon and claims the benefit of
priority from the prior Japanese Patent Application No.
2002-115969, filed on Apr. 18, 2002; the entire contents of which
are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a current detection
equipment and a semiconductor device, and more particularly, to a
current detection equipment which detects a current flowing through
a conductor in a semiconductor device, semiconductor device package
or various kinds of electric circuit equipment by a magnetic
induction or magnetic field detection, and the semiconductor device
using the same.
[0003] A current detection equipment for detecting a current from
the outside is required in order to measure a current flowing
through a lead or a conductor provided in a semiconductor device,
or various kinds of electric elements or electric circuits.
[0004] For example, the semiconductor device for electric power has
evolved into the so-called "module type" with increase in capacity,
and the module is becoming larger. However, unevenness of the
internal current which originates in parasitic factors, such as an
inductance, in a module arises. When the performance of the module
is improved, for example by increasing a current capacity or by
increasing the operation speed of the module, a destruction of
elements in the module may arise owing to the unevenness of the
current, and it is becoming a problem.
[0005] On the other hand, a current probe cannot be inserted in an
inside of the module on the occasion of measurement of the current
in a module type semiconductor device. For this reason, unless the
internal structure is changed, measurement of current in a module
type semiconductor element is practically impossible. On the other
hand, if the internal structure of the module is changed in order
to provide the conventional measurement equipment such as current
transformers, since the inductance itself changes, conditions of
measurement also changes and as the results the current to be
measured is changed. This leads lower accuracy of measurement. For
this reason, a minute current probe for measuring without changing
the electrode structure inside a module etc. is being needed.
[0006] Conventionally, for detection of a short circuit or for
feedback on gate voltage, the current is measured by using an
element with a current sensor or by using a current probe called
"CT (Current Transformer: current transformer)" etc.
[0007] The element with a current sensor has been developed in IGBT
(Insulated Gate Bipolar Transistor). This IGBT chip has the
structure where the emitter is divided into a divided emitter and a
main emitter. In the case of this element, in the state where gate
is ON, the current which is flowing through the main element can be
estimated by detecting the voltage decrease at the resistance which
is inserted between the divided emitter and the main emitter.
[0008] However, in this system, since a current sensing part is
made as a part of the chip of IGBT, there are the following
problems:
[0009] (1) Chip structure becomes complicated.
[0010] (2) The effective area of the chip becomes smaller.
[0011] (3) The output of the voltage decrease from the emitter
resistance in the IGBT varies.
[0012] (4) The linearity between the current which actually flows,
and an output is low.
[0013] (5) The output is not insulated.
[0014] Chip cost increases as a result of the above (1). The
current which can be passed becomes smaller as a result of (2).
Measurement accuracy falls as a result of (3). The design of a
detection circuit becomes difficult and complicated as a result of
(4). Insulating device such as a photo-coupler is required in order
to insulate the output as a result of (5). Consequently, the output
becomes binary ("1" and "0"), and analog values, such as a current
value, cannot be fed back to the control side.
[0015] On the other hand, CT convergence the current magnetic flux
generated around a conductor with a magnetic core, and detects the
current as an electromagnetic induction current produced in a coil.
However, the magnetic core has the following problems:
[0016] (1) In order to prevent the magnetic saturation in a large
current condition, CT is enlarged.
[0017] (2) The inductance of the main circuit increases in
accordance with the form of the core. As a result, current will
increase by forming a current path different form original one when
a large core of CT is inserted in the circuit.
[0018] Because of these problems, when CT is installed in a small
semiconductor device, it is difficult to detect current correctly
without affecting the operation of the semiconductor device.
[0019] As explained above, it was difficult to measure current
correctly and easily, without affecting the operation in insides,
of devices, such as a semiconductor device, with the conventional
technology.
SUMMARY OF THE INVENTION
[0020] According to an embodiment of the present invention, there
is provided a current detection equipment comprising: a first coil;
and a second coil connected in series with the first coil, the
current detection equipment being capable of detecting a current
flowing through an object which is provided between the first and
second coils or provided in a vicinity of the first or second coil,
and each of the first and second coils having first conductive
patterns provided on a surface of a substrate, a second conductive
patterns provided on a back of the substrate and connecting parts
which connect the first and second conductive patterns.
[0021] According to other embodiment of the invention, there is
provided a current detection equipment comprising: a substrate
having a notch or a hole; and a first and a second coils provided
on opposite sides of the notch or the hole, each of the first and
second coils having first conductive patterns provided on a surface
of the substrate, a second conductive patterns provided on a back
of the substrate and connecting parts which connect the first and
second conductive patterns.
[0022] According to other embodiment of the invention, there is
provided a current detection equipment comprising: a first
substrate having a first coil; a second substrate having a second
coil; and a spacer provided between the first and second
substrates, the first coil having first conductive patterns
provided on a surface of the first substrate, a second conductive
patterns provided on a back of the first substrate and connecting
parts which connect the first and second conductive patterns, the
second coil having first conductive patterns provided on a surface
of the second substrate, a second conductive patterns provided on a
back of the second substrate and connecting parts which connect the
first and second conductive patterns.
[0023] According to other embodiment of the invention, there is
provided a semiconductor device comprising: a semiconductor
element; and a current detection equipment including a substrate
having a notch or a hole; and a first and a second coils provided
on opposite sides of the notch or the hole, each of the first and
second coils having first conductive patterns provided on a surface
of the substrate, a second conductive patterns provided on a back
of the substrate and connecting parts which connect the first and
second conductive patterns, and at least a part of a current
flowing in the semiconductor element being detected by the current
detection equipment.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The present invention will be understood more fully from the
detailed description given herebelow and from the accompanying
drawings of the embodiments of the invention. However, the drawings
are not intended to imply limitation of the invention to a specific
embodiment, but are for explanation and understanding only.
[0025] In the drawings:
[0026] FIGS. 1A through 1C are schematic diagrams illustrating the
probe part of the current detection equipment concerning the
embodiment of the present invention, where FIG. 1A is a plan view,
FIG. 1B is a front view, and FIG. 1C is a left-hand side view
thereof;
[0027] FIGS. 2A and 2B are schematic diagrams illustrating the
connection relations of the pair of coil parts C;
[0028] FIG. 3 is a schematic diagram showing the electromagnetic
induction action produced in the coil parts C;
[0029] FIG. 4 is a schematic diagram illustrating other examples of
the current detection equipment of the present invention;
[0030] FIG. 5 shows an example where the hole H having a shape,
such as a slit, is formed in the substrate 10, and the coil parts C
can be formed at the both sides of the hole H;
[0031] FIGS. 6A through 6C are schematic diagrams illustrating
another example of the current detection equipment of the present
invention;
[0032] FIG. 7 is a schematic diagram showing the example of the
coil part C in the present invention;
[0033] FIG. 8 is a schematic diagram showing another example of the
coil part C in the present invention;
[0034] FIGS. 9A and 9B are schematic diagrams illustrating the
measurement systems which use the current detection equipment of
the present invention;
[0035] FIG. 10 is a schematic diagram showing the principal part of
the semiconductor device which includes the current detection
equipment of the present invention;
[0036] FIG. 11 is a schematic diagram illustrating the principal
part of another semiconductor device which includes the current
detection equipment of the present invention;
[0037] FIGS. 12 and 13 show the examples where the circuits (34,
40,42) are prepared near the probe part P, and the signal is
inputted directly;
[0038] FIGS. 14A and 14B are schematic diagrams showing the example
of the semiconductor device which includes the current detection
equipment of the present invention;
[0039] FIG. 15 shows an outline of the IGBT 64;
[0040] FIG. 16 is a diagram of an equivalent circuit of this module
for electric power control;
[0041] FIG. 17 is an enlarged perspective diagram showing a
principal part of the probe part;
[0042] FIG. 18 is a schematic diagram showing the example of the
arrangement of the probe part P;
[0043] FIG. 19 shows the structure where the probe part P is formed
in a gate substrate;
[0044] FIG. 20A shows a longitudinal section of the module, and
FIG. 20B shows the A-A line sectional view;
[0045] FIG. 21 is a schematic diagram showing another semiconductor
device which includes the current detection equipment of the
present invention;
[0046] FIG. 22 is a schematic diagram showing the equivalent
circuit of the element part;
[0047] FIG. 23A shows a principal part sectional view near a
substrate 84, and FIG. 23B shows a plane view seen from the
back;
[0048] FIGS. 24A and 24B show the schematic sectional views of the
examples of the probe part P;
[0049] FIG. 25 is an internal enlargement showing the example of
transformation of a semiconductor device expressed in FIG. 21;
[0050] FIGS. 26A and 26B are conceptual figures showing an analysis
model, where FIG. 26A is a plan view and FIG. 26B is a side view of
the analysis model;
[0051] FIG. 27 is a schematic diagram showing the probe part of the
current detection equipment fabricated in this example;
[0052] FIG. 28 is a schematic diagram showing the coil section of a
probe part;
[0053] FIGS. 29A through 29C are schematic diagrams showing the
more concrete structure of the probe part P;
[0054] FIG. 29A shows a plan view of the probe part, FIG. 29B shows
a front view thereof, and FIG. 29C shows a side view thereof;
[0055] FIG. 30A shows the experimental setup;
[0056] FIG. 30B is a graphical representation showing the waveform
when inserting a copper plate in a probe part and passing pulse
current;
[0057] FIG. 31 is a schematic diagram showing this measuring
method;
[0058] FIGS. 32 and 33 are graphical representations showing these
measurement results;
[0059] FIG. 34 is a graphical representation showing the relation
between current change rate di/dt and output voltage;
[0060] FIG. 35 is a graphical representation showing the
distribution of the relative measurement accuracy of two or more
probe parts;
[0061] FIG. 36 is a circuit diagram showing the principal part of
the integration circuit used in this example;
[0062] FIG. 37 is a graphical representation showing the waveform
which observed the current of 16 semiconductor chips;
[0063] FIG. 38A expresses the waveform adding the current
measurement data of 16 chips measured by the probe part of the
invention; and
[0064] FIG. 38B is a graphical representation showing the main
current waveform measured with the conventional CT type probe.
DETAILED DESCRIPTION
[0065] Referring to the accompanying drawings, embodiments of the
present invention will now be described in detail.
[0066] FIGS. 1A through 1C are schematic diagrams illustrating the
probe part of the current detection equipment concerning the
embodiment of the present invention. That is, FIG. 1A is a plan
view, FIG. 1B is a front view, and FIG. 1C is a left-hand side view
thereof.
[0067] In the case of this example, the pattern 12 which consists
of an electric conductor is formed in the surface and the back of a
substrate 10. As a material of the substrate 10, an insulating
material or semi-insulating material such as resin, ceramic as
silicon can be used as will be explained in full detail later. The
pattern 12 can be formed by various kinds of metals including
copper (Cu), aluminum (Al), and gold (Au), and by other conductive
materials.
[0068] And as for these patterns 12, the surface side and the back
side of the substrate 10 are connected by the through holes 14
which penetrate the substrate 10. Here, in order to connect the
patterns, between the different layers of the substrate 10, through
holes 14 have a structure where the inside of the hole which
penetrates a substrate 10 is filled up with a conductor.
[0069] Thus, a pair of coil parts C are formed by the patterns 12
formed on both sides of the substrate 10 and the through holes 14
which connect these patterns.
[0070] Moreover, a substrate 10 has the return wiring 16 inside,
which is constituted by an electric conduction layer. By providing
this return wiring 16, one side of the probe needs not have any
conduction pattern, thus an opening can be formed for inserting
current conduction material to be measured. This return wiring 16
passes along near the center of each of coil parts, and reaches
near the end of the coil part C. This arrangement (providing the
wiring 16 at the center of coil) is designed to minimize influence
other magnetic field etc. And this return wiring 16 is connected to
the joint wiring 18 for connecting the pair of coil parts in
series.
[0071] Thus, the both ends of the pair of coil parts C connected in
series are connected to the output extraction terminal 20 provided
on the same side as the joint wiring 18. A resistance which is not
illustrated is connected to the both ends of these extraction
terminals 20 in parallel as will be explained in full detail
later.
[0072] In the case of the example shown in FIG. 1, the coil part C
is formed on the substrate 10 which has the plane form of a
horseshoe. That is, each of the patterns 12 is formed at a
predetermined angle to the center axis of the coil part C, and the
through holes 14 are formed at the both ends of the patterns 12.
The patterns 12 are formed at the almost same angle to the center
axis of the coil part C in both of front and back sides of the
substrate 10, and patterns 12 on the surface and the back of the
substrate 10 are connected electrically by the through holes
14.
[0073] Instead of the through holes 14, the pattern of an
electrically conductive material may be formed on the side surfaces
of the substrate 10 in order to connect the patterns 12 of the
front surface and the back surface of the substrate 10, as will be
explained in full detail later.
[0074] A conductor S to be measured is inserted between the pair of
coil parts C on the substrate which has a planar shape of a
horseshoe. The cross-sectional form of the conductor S is not
limited to the specific example shown in FIG. 1, but any conductor
which is able to be inserted between the pair of coil parts C may
be measured.
[0075] FIG. 2 is a schematic diagram illustrating the connection
relation of the pair of coil parts C. That is, the two coil parts
Care connected in series, and the conductor S is inserted in the
portion sandwiched between the coil parts C. As expressed in FIG.
2A, the return wiring 16 may be formed outside of the coil part C,
or as expressed in FIG. 2B, it may be formed inside of the coil
part C. In order to ensure the noise-proof nature to a noise caused
by an external stray magnetic field etc., it is desirable to
provide the wiring 16 inside the coil as shown in FIG. 2B. On the
other hand, it is more advantageous to form the return wirings 16
outside of the coils in respect of the easiness of manufacture, as
illustrated in FIG. 2A.
[0076] As shown in FIGS. 2A and 2B, the pair of coil parts C which
are connected in series produce a voltage between the extraction
terminals 20 at their both ends in response to a change of the
magnetic field generated by a current which flows through the
conductor S to be measured. This voltage can be measured between
the both ends of the resistance R which is connected to the
extraction terminals 20.
[0077] FIG. 3 is a schematic diagram showing the electromagnetic
induction action produced in the coil parts C. That is, a magnetic
field M is formed by the current I which flows through the
conductor S to be measured. By this magnetic field M, the voltage
of the direction expressed with the arrow is generated in the coil
parts C. By measuring that voltage between the both ends of the
resistance which is connected in parallel with the coils, the
differentiation of the current I which flows through the conductor
S can be obtained. By using an integration circuit, for example,
this differentiation can be reconstructed into an original waveform
of the current I. Alternatively, control of a semiconductor element
or a circuit can also be performed, by using the differentiation of
the current as it is.
[0078] Here, the largest output will be obtained, if it is arranged
so that the current I which flows through the conductor S becomes
almost perpendicular to a plane which includes the center axes of
two coil parts C. Moreover, since the strong current magnetic field
formed near the conductor S can be picked up if the spacing between
two coil parts C is made as narrow as possible, a large output can
be obtained.
[0079] .DELTA.T of the differentiation .DELTA.I/.DELTA.T obtained
in the detection equipment is determined by the time constant of
the resistance R which is connected to the coil parts C, and by the
time constant of the inductance L of the coil parts C. Therefore,
if inductance L is large, an output will become large, and an
output will become small if Resistance R is small. Here, the value
of Resistance R and the value of the inductance L of the coils are
determined by a time constant which is needed for the system, and
by a size and a number of turns of the coil parts C, etc.
[0080] Therefore, when the responsibility is important, what is
necessary is just to use a smaller coil and smaller resistance to
while making some outputs into a sacrifice. On the contrary, when a
large output is required, what is necessary is just to use a large
coil and a large resistance.
[0081] Moreover, as illustrated in FIGS. 1A through 2B, the winding
directions of the coil parts C are made so that the induction
voltage generated at each coil becomes in the same direction. That
is, it is formed so that the induction voltage produced by the
current of the conductor S in one coil part C and the induction
voltage produced by the current of the conductor S in the coil part
C of another side may be added. Thus, the induction voltage
produced in each coil part C by the current which flows through the
conductor S can be doubled and easily detected.
[0082] Furthermore, when an external magnetic field is applied to
the pair of coil parts, induction voltage is generated in an
opposite direction in each coil part C. Therefore, the influence of
an external magnetic field can be canceled, by connecting the coil
parts C in series. That is, the measurement error resulting from an
external magnetic field can be suppressed.
[0083] FIG. 4 is a schematic diagram illustrating other examples of
the current detection equipment of the present invention. That is,
in the case of this example, slit-like notch G is prepared in the
end of a substrate 10 on which an electric circuit etc. is formed,
and the coil parts C are formed in the both sides of the notch G.
The current which flows through a conductor S can be measured by
inserting the conductor S in the notch G. Here, the form of notch G
is not limited in the shape of a slit. It may be semicircular or
square, for example, and may suitably be determined according to
the cross-sectional form and the size of the conductor S to be
measured.
[0084] In the case of this example, circuits, such as an
integration measurement circuit, a gate circuit, a control circuit,
and an electric power main circuit, which are not illustrated, may
also be formed on the substrate 10. These circuits can be connected
with the extraction terminals 20 of the coil parts C directly.
Moreover, when an electric power main circuit is formed on a
printed circuit board and the object S to be measured is patterned,
the coils C and the object S can be formed on the same substrate by
using a patterning technique, and thus, the fabrication cost can be
lowered compared with the case where the coils are formed
separately.
[0085] On the other hand, as illustrated in FIG. 5, the hole H
having a shape, such as a slit, maybe formed in the substrate 10,
and the coil parts C can be formed at the both sides of the hole H.
Then the current which flows through the conductor S which
penetrates the hole H can be measured. In this example, the shape
of the hole H is not limited to a slit. The form of the hole H can
determined suitably according to the cross-sectional form and the
size of the conductor S to be measured.
[0086] FIGS. 6A through 6C are schematic diagrams illustrating
another example of the current detection equipment of the present
invention.
[0087] In the case of this example, the probe is formed by
laminating two or more substrates. That is, substrate 10A in which
the first coil part C is formed, and substrate 10B in which the
second coil part C is formed are stuck through the spacer 10C. And
the conductor S to be measured is inserted in the gap between the
substrates 10A and 10B. Although the case where spacer 10C is
prepared only in one end side of a probe is shown in FIGS. 6A
through 6C, the spacer may be prepared in the both sides of the
probe part P, respectively. In this case, the object S to be
measured is inserted in the opening formed between the substrates
10A and 10B.
[0088] In the case of this example, the coil parts C can fully be
brought close to the conductor S to be measured. As a result, the
current magnetic field of a high density formed near the conductor
S can be picked up, and an output increases. Furthermore, the
external magnetic fields which the coil parts C receive
respectively can be made almost the same by making two coil parts
approach. As a result, it becomes possible to make the detection
equipment less susceptible to the magnetic noises (for example,
stray magnetic field which the current of other wiring which is not
illustrated forms) from the circumference.
[0089] FIG. 7 is a schematic diagram showing the example of the
coil part C in the present invention. That is, two or more
substantially parallel patterns 12 are formed on the surface of a
substrate 10, and two or more substantially parallel patterns 12
are formed on the back side of the substrate 10. And these patterns
12 of the surface and the back sides are connected by the through
holes 14 and form a continuous coil part C.
[0090] If the interval of the patterns 12 is narrowed and the
number of patterns 12 is increased, the number of turns of the coil
part C can be increased, and thus, the output of current detection
can be reinforced. For this purpose, it is good to arrange the
adjoining through holes 14 alternately as shown in the figure. That
is, if an actual formation process is taken into consideration, the
diameter of the through hole 14 will become larger rather than the
width of the patterns 12 in many cases. Therefore, by arranging the
through holes 14 alternately, the interval of the adjoining
patterns 12 can be narrowed and formation density can be made
higher.
[0091] FIG. 8 is a schematic diagram showing another example of the
coil part C in the present invention. That is, in this example, the
patterns 13 are formed on the sides of the substrate 10, and the
patterns 12 on the front side and the back side of the substrate 10
are connected by these patterns 13. Thus, it becomes easy to form
the patterns 12 by high density by using the patterns 13 of the
sides instead of the through holes 14.
[0092] FIGS. 9A and 9B are schematic diagrams illustrating the
measurement systems which use the current detection equipment of
the present invention. That is, in the case of the example
illustrated in FIG. 9A, the signal from the extraction terminals 20
of the coil parts C is inputted into the integration circuit 34
through the coaxial wiring 30, and the waveform of the current
flowing through the conductor S is reconstructed by an integration
processing performed by the integration circuit 34. This waveform
can be observed through the coaxial wiring 35 with measuring
instruments, such as an oscilloscope 36, for example.
[0093] Alternatively, as illustrated in FIG. 9B, the signal from
the extraction terminals 20 of the coil parts C can be inputted
into the integration circuit through the twist pair wiring 32.
[0094] FIG. 10 is a schematic diagram showing the principal part of
the semiconductor device which includes the current detection
equipment of the present invention. This semiconductor device has a
semiconductor element 50 for electric power control or switching
such as a Power MOSFET and an IGBT.
[0095] The gate control circuit which is not illustrated is
provided in the inside or the exterior of this semiconductor
device, and a pulse width modulation signal (PWMS) is supplied
therefrom. This PWM signal (PWMS) is inputted into the drive
circuit 39, and the gate of the semiconductor element 50 is driven
by the output of the drive circuit 39 to perform control or
switching of an electric power.
[0096] The current which flows through the conductor S connected to
the main electrode (an emitter, a collector, a source, or a drain)
of the semiconductor element 50 is detected by the probe part P of
the current detection equipment of the invention. And the voltage
measured at the both ends of the resistance R connected to the
extraction terminals 20 of the probe part P is reconstructed into a
current waveform in the integration circuit 34 through the coaxial
wiring 30.
[0097] The obtained current waveform data is compared with a
predetermined restriction current value in the comparison circuit
38. The comparison circuit 38 may be equipped with the offset
cancellation circuit for compensating the offset included in the
inputted current waveform data. Thus, it becomes possible to adjust
the offset of the integration circuit when the semiconductor
element is in the state of OFF.
[0098] The comparison circuit 38 outputs the short circuit signal
(SCS) in order to indicate that the semiconductor element 50 is
short-circuited, when the current data outputted from the
integration circuit 34 exceeds a predetermined restriction current
value. If this short circuit signal (SCS) is received, the drive
circuit 39 will output an interception gate signal prepared for the
case of a short circuit in order to turn OFF (off) the gate of the
semiconductor element 50, and to intercept the current.
[0099] As explained above, in the case of this example, the monitor
of the output current of a semiconductor device 50 is made with a
current sensing device, and if a short circuit state is generated,
the current may be intercepted immediately. By using the current
detection equipment of the invention, it becomes possible to
monitor the output current correctly without affecting operation of
the semiconductor element 50, and the size of the whole
semiconductor device can be kept compact. The measurement point of
the current by the probe P may not be limited to a collector side,
but may be measured at an emitter side, and may be measured at both
points.
[0100] FIG. 11 is a schematic diagram illustrating the principal
part of another semiconductor device which includes the current
detection equipment of the present invention. This semiconductor
device also has a semiconductor element 50 for electric power
control or switching such as a Power MOSFET and an IGBT.
[0101] Also in this semiconductor device, the probe part P which
measures the output current of the semiconductor element 50 is
provided. And the current differentiation value outputted from the
probe part P is amplified in the amplification circuit 40, and is
inputted into the drive circuit 42 with a PWM signal.
[0102] Based on the current differentiation signal (dI/dt) inputted
from the amplification circuit 40, the short circuit of the
semiconductor element 50 is detected, or the drive circuit 42
judges the deviation of the output current from the semiconductor
element 50. And the gate control signal optimized based on these
judgment results is given to the gate of the semiconductor element
50.
[0103] In the examples expressed in FIGS. 10 and 11, the output
signal from the probe part P of current detection equipment is
inputted into the integration circuit 34 or the amplification
circuit 40 through the coaxial wiring 30. On the other hand, as
expressed in FIGS. 12 and 13, these circuits maybe prepared near
the probe part P, and the signal may be inputted directly. In these
cases, these circuits may be connected with the coil part C with
substrate wiring by forming the circuits on the substrate 10 in
which the coil part C is formed.
[0104] Moreover, as shown in FIG. 13, a status signal (SSG)
indicating the state of the gate of the semiconductor element 50
may be inputted from the drive circuit 42 to the integration
circuit 34, and the integration circuit 34 may supply a current
signal (CSG) to the drive circuit 42 while taking the status signal
into consideration.
[0105] FIGS. 14A and 14B are schematic diagrams showing the example
of the semiconductor device which includes the current detection
equipment of the present invention. That is, the semiconductor
device expressed in these figures is a module for electric power
control. FIG. 14A is an internal plane view, and FIG. 14B is a side
view.
[0106] This module has four DBC (Direct Bonded Cupper) substrates
62 provided on the heat dissipation substrate 60 which consist of
copper (Cu). The DBC substrates 62 have a structure where the thin
film pattern which consists of copper is formed on the surface of a
ceramic substrate. On the copper pattern, IGBTs 64 and the free
wheeling diodes 66 are mounted.
[0107] As expressed in FIG. 15, IGBT 64 has a gate electrode 64G
and two or more emitter electrodes 64E on the surface side, and has
a collector electrode 64C on the back side.
[0108] Gate electrode 64G and emitter electrodes 64E are connected
to the copper pattern on the DBC substrate 62 by the bonding wire
68, respectively. Collector electrode 64C is directly connected to
the copper pattern on which IGBT 64 is mounted.
[0109] Similarly, as for the free wheeling diode 66, the electrode
on the side of the surface is connected to the copper pattern of
the DBC substrate 62 by the bonding wires 68. On the other hand,
the electrode on the back side is directly connected to the copper
pattern on which the diode 66 is mounted.
[0110] And each of these electrodes is suitably connected to the
external circuit or external apparatus (not shown) through the
pullout wires 69.
[0111] FIG. 16 is a diagram of an equivalent circuit of this module
for electric power control. That is, this figure expresses the
circuit on one DBC substrate 62, and shows that a parallel
connection of four IGBTs 64 and the two free wheeling diodes 66 is
made.
[0112] And in the present invention, measurement of the current is
enabled by, for example, placing the probe part P at the bonding
wire 68 connected to emitter electrode 64E of IGBT 64, and at the
bonding wire 68 connected to the free wheeling diode 66. However,
measurement of the current may be performed only at the IGBT 64, or
only at the diode 66. Instead, measurement of the current may be
performed not only in one element but in two or more elements.
Furthermore, measurement may be performed in any portion of the
main electrode wiring in the module, for example, measurement can
be performed at the collector or emitter wire frame inside or
outside of the package.
[0113] FIG. 17 is an enlarged perspective diagram showing a
principal part of the probe part. This probe part P has a structure
which is illustrated in FIGS. 6A through 6C. By inserting two or
more bonding wires 68 in the gap of the pair of coil parts C, the
current which flows through the wire 68 can be detected. Bonding
wire and the coil center line may preferably be perpendicular to
each other.
[0114] As mentioned above, in the semiconductor device expressed in
FIGS. 14A through 17, the current which flows IGBT 64 and the free
wheeling diode 66 can be measured in real time. For example, urgent
interception at the time of a short circuit which was mentioned
above about FIGS. 10 through 13, feedback to the gate control based
on the measured current data, etc. can be performed certainly and
easily.
[0115] According to the invention, the current can be measured
without affecting the operation of IGBT 64 or the free wheeling
diode 66. Besides, since the probe part P can be formed compactly,
it is not necessary to enlarge modular size to add the measurement
system.
[0116] As a result, a highly reliable, highly efficient and compact
semiconductor devices, such as a module for electric power control,
can be offered.
[0117] Although the examples of the semiconductor devices which
include the current detection equipment of the invention have been
explained in the above, the invention is not limited to these
specific examples. For example, the invention is applicable
similarly to MOSFET, a thyristor, GTO, a diode, etc. besides
IGBT.
[0118] FIG. 18 is a schematic diagram showing the example of the
arrangement of the probe part P. That is, when taking out current
from the pattern of the DBC substrate 62 through the pullout wire
70 (it is also called "bus" or a "stub" wire frame etc.), such as a
copper plate, the probe part P can be placed at this pullout wire
70, and current can also be measured.
[0119] Moreover, as illustrated in FIG. 19, this probe part P may
be formed in a gate substrate. That is, in the case of the example
expressed in this figure, the DBC substrate 62 is formed on the
copper substrate 60, and IGBT 64 is mounted on it.
[0120] And the gate substrate (printed circuit board) 74 is further
formed with a predetermined spacing above the IGBT 64. This gate
substrate 74 has the drive circuit which outputs the signal which
controls the gate of IGBT 64. On the other hand, with the pullout
electrode 76, the main electrode (a collector or emitter) of IGBT
64 penetrates the gate substrate 74, and is taken out above the
module.
[0121] And if the probe part P of the current detection equipment
of the invention is placed so as to sandwich the pullout electrode
76 at the gate substrate 74, the main electrode current can be
measured.
[0122] Moreover, as expressed in FIGS. 20A and 20B, the probe part
P may be provided only in the either side of the pullout electrodes
76. That is, FIG. 20A shows a longitudinal section of the module,
and FIG. 20B shows the A-A line sectional view.
[0123] In the case of the module illustrated in FIGS. 20A and 20B,
the pullout electrodes 76 are provided in the vicinity of the end
of the module. Therefore, the pullout electrodes 76 are placed
outside of the gate substrate 74.
[0124] In such a case, the probe parts P may be placed on the one
side of the pullout electrodes 76, without sandwiching them, as
shown in FIGS. 20A and 20B. Even when the probe parts P are
arranged in this way without inserting the conductors to be
measured, detection of the current is also possible although the
output obtained declines, as will be explained in full detail as an
example of the invention later. Also in this case, the effect to
cancel the influence of an external magnetic field is
simultaneously maintained by preparing a pair of coil parts C.
[0125] Therefore, what is necessary is just to arrange the probe
part P near the conductor to be measured, when it is difficult to
locate the probe part P in the place to sandwich the conductor to
be measured.
[0126] FIG. 21 is a schematic diagram showing another semiconductor
device which includes the current detection equipment of the
present invention.
[0127] And FIG. 22 is a schematic diagram showing the equivalent
circuit of the element part.
[0128] That is, this example has a structure where two
semiconductor elements 89 for electric power switching are
connected in series, and terminals 90A, 90C, and 90B are taken out
from the both ends and the connection middle point, respectively.
These semiconductor elements 89 are packaged in the enclosure 82
formed on the substrate 80. And the main electrode terminals
90A-90C and the gate control terminal 92 are formed on it.
[0129] The main electrode terminals 90A-90C are installed in the
place where electric power wiring can be connected to the bolts 85
for connection through the washer 83 which consists of copper etc.
in the extraction part. And a substrate 84 is formed in the place
which encloses the circumference of these washers 83, and the probe
parts P of the current detection equipment of the invention are
formed on this substrate.
[0130] The outputs from the probe parts P are drawn to the control
substrate 86 through the connection wiring 87. The control
substrate 86 has the integration circuit or amplification circuit
for integrating or amplifying the output signals from the probe
parts P, and a comparison circuit for comparing with a
predetermined value. Moreover, the control substrate 86 may also
have a gate drive circuit for controlling each of the semiconductor
element 89 etc.
[0131] And the control signal from this gate drive circuit is
inputted into the gate control terminal 92 through wiring 88.
[0132] FIG. 23A shows a principal part sectional view near a
substrate 84, and FIG. 23B shows a plane view seen from the back.
The substrate 84 is formed of an insulating material and openings
84H for raising the breakdown voltage along its surface plane are
prepared suitably.
[0133] The terminal current can be measured by placing the probe
parts P which have a coil in the circumferences of the washers
83.
[0134] FIGS. 24A and 24B show the schematic sectional views of the
examples of the probe part P.
[0135] That is, instead of forming the continuous substrate 84, as
illustrated in FIGS. 24A and 24B, the probe parts P may be provided
by forming the coil parts C in the substrates of a form which
encloses only the circumference of a washer 83.
[0136] FIG. 25 is an internal enlargement showing the example of
transformation of a semiconductor device expressed in FIG. 21. That
is, the connection wiring 94 connects the electrodes of the
semiconductor elements 89 which are mounted on the substrate 80 (or
DBC substrate etc.) and the main terminals 90A-90C.
[0137] As expressed in FIG. 25, the current can also be measured by
placing the probe part P of the current detection equipment of the
invention so as to sandwich the connection wiring 94.
[0138] In the above, the embodiments of the invention has been
explained, referring to FIGS. 1A through 25.
[0139] Hereafter, the embodiments of the present invention will be
explained in more detail, referring to examples.
FIRST EXAMPLE
[0140] First, the current detection equipment which measures the
current which flows through the bonding wire connected to a
semiconductor chip on a DBC substrate which was mentioned above
about FIGS. 14A through 17 will be explained as a first example of
the invention. That is, the probe part P for carrying out a
real-time measurement of the current which flows through sixteen
bonding wires (0.3 mm .phi.) which consist of aluminum (Al) was
studied.
[0141] FIGS. 26A and 26B are conceptual figures showing an analysis
model. That is, FIG. 26A is a plan view and FIG. 26B is a side view
of the analysis model.
[0142] That is, sixteen aluminum bonding wires were approximated as
the aluminum board S whose size is 12 mm.times.0.3 mm.times.16 mm
so that the outermost form might become equal, and the copper wire
coil C having a section of 1 mm.sup.2 (1 mm.times.1 mm) was
arranged in the interval pitch of 0.8 mm at the positions in a
range of 0.8 mm through 1.3 mm from the aluminum board S.
[0143] Moreover, since the probe part P of the invention tends to
received a noise from the magnetic flux by the current of the same
direction as a bonding wire S, the noise sources 1 (NS1) and 2
(NS2) were arranged, and the influence of the external magnetic
flux was also analyzed.
[0144] Table 1 summarizes the mutual inductance between the coil
and the bonding wires taken from the center of the measured
conductor, i.e., sixteen aluminum bonding wires.
1TABLE 1 Xa [mm] 0.2 1.0 1.8 2.6 3.4 4.2 5.0 5.8 .SIGMA. M [nH]
0.046 0.046 0.045 0.045 0.045 0.043 0.040 0.032 .fwdarw. 0.342
[0145] Here, the resistance and the inductance of one turn of the
coil C are 6.9 mohm and 1.92 nH (f=1 Hz), respectively. Table 1
shows the mutual inductance of the coil 1 turn and bonding wires in
the distance Xa from a center.
[0146] Table 1 shows that when the coil pitch is 0.4 mm and the
coil installed in the both sides of the bonding wires is 64 turns,
the mutual inductance M=0.342.times.2.times.2.times.2=2.74 nH. In
current change rate di/dt=100 A/.mu.s, the open end voltage of 274
mV is obtained.
[0147] Next, the inventors have examined the mutual inductance of
the coil and the noise source 1 (NS1).
[0148] Table 2 shows a mutual inductance between the coil and noise
source 1 in the case where the noise source 1 is located from the
bonding wires S in a distance of 10 mm.
2TABLE 2 Xa [mm] 0.2 1.0 1.8 2.6 3.4 4.2 5.0 5.8 .SIGMA. MI1 [nH]
-0.011 -0.011 -0.011 -0.011 -0.010 -0.010 -0.009 -0.009 .fwdarw.
-0.082 MI2 [nH] 0.009 0.009 0.009 0.009 0.008 0.008 0.008 0.007
.fwdarw. 0.067 MIS [nH] -0.002 -0.002 -0.002 -0.002 -0.002 -0.002
-0.002 -0.001 .fwdarw. -0.015
[0149] Further in this case the coil parts C were provided in both
sides of the conductor S. In the table, the mutual inductance
between the noise source 1 and the coil which is closer to the
noise source is denoted by the symbol MI1. The mutual inductance
between the noise source 1 and the coil which is remoter to the
noise source is denoted by the symbol MI2. The sum of the mutual
inductance MI1 and MI2 is denoted by the symbol MIS.
[0150] M=0.015 nH was obtained by providing the coil parts C in the
both sides of the conductor S to be measured, and thereby canceling
the influence of the external magnetic flux between these coil
parts.
[0151] This mutual inductance is equivalent to about 4 percent of a
signal level. Thus, there is little influence of the external
current in the position distant 10 mm or more. Therefore, in an
actual semiconductor device, it is thought that the influence from
other electrode terminals etc. can be neglected.
[0152] Next, the inventors have examined the mutual inductance of
the coils and the noise source 2 (NS2) when the coil parts C are
provided in both sides of the conductor S.
[0153] Table 3 shows a mutual inductance between the coil and the
noise source 2 in the case where the noise source 2 is located from
the bonding wires S in the distance of 5 mm.
3TABLE 3 Xa [mm] 0.2 1.0 1.8 2.6 3.4 4.2 5.0 5.8 .SIGMA. MI1 [nH]
-0.025 -0.025 -0.024 -0.023 -0.022 -0.021 -0.019 -0.016 .fwdarw.
-0.175 MI2 [nH] 0.019 0.019 0.018 0.018 0.017 0.016 0.015 0.013
.fwdarw. 0.134 MIS [nH] -0.006 -0.006 -0.006 -0.006 -0.005 -0.005
-0.004 -0.003 .fwdarw. -0.041
[0154] In the table, the mutual inductance between the noise source
1 and the coil which is closer to the noise source is also denoted
by the symbol MI1. The mutual inductance between the noise source 1
and the coil which is remoter to the noise source is denoted by the
symbol MI2. The sum of the mutual inductance MI1 and MI2 is denoted
by the symbol MIS.
[0155] Also in this case, M=0.041 nH was obtained by providing the
coil parts C in the both sides of the conductor S to be measured,
and thereby canceling the influence of the external magnetic flux
between these coil parts. This mutual inductance is equivalent to
about 12 percent of a signal level. Thus, it has some influences of
current with a position of less than 10 mm from the bonding wires.
Therefore, in an actual semiconductor device, the influence of the
current which flows through the copper pattern near the chip may
preferably be taken into consideration in some case.
[0156] However, the influence of current other than the current
component which flows in the same direction as the bonding wires is
small. Therefore, in the case of the DBC substrate mentioned above,
it is thought that there is little influence is exerted by a copper
pattern.
[0157] Next, the inventors have examined the mutual inductance when
the position of coil C shifts up and down. Table 4 shows a mutual
inductance when coil C shifts 0.1 mm towards the lower side.
4TABLE 4 Xa [mm] 0.2 1.0 1.8 2.6 3.4 4.2 5.0 5.8 .SIGMA. upper [nH]
0.045 0.045 0.045 0.044 0.044 0.042 0.039 0.030 .fwdarw. 0.334
lower [nH] 0.047 0.048 0.045 0.045 0.046 0.045 0.042 0.033 .fwdarw.
0.351
[0158] The average of the mutual inductance of the both sides of
the bonding wires is M=0.342 nH. That is, it seems thst it is not
necessary to consider the influence since it is compensated by the
coils of both sides even if there is "a position error." When a
coil shifts upwards, the items in the upper and lower columns in
the Table 4 become reverse.
[0159] Next, the inventors have examined the mutual inductance at
the time of changing the diameter of the coil. Table 5 shows the
mutual inductance between the coil and the bonding wires at the
time of enlarging the coil cross-section area, having used the
diameter of the coil as 2 mm.times.1 mm.
[0160] Table 5 shows that in the case where the coils (64 turns)
are installed in the both sides of the bonding wires with the coil
pitch of 0.4 mm, the mutual inductance is M=0.684
.times.2.times.2.times.2=5.47 nH. That is, if current change rate
di/dt=100 A/.mu.s, then the open end voltage of 547 mV are
obtained.
5TABLE 5 Xa [mm] 0.2 1.0 1.8 2.6 3.4 4.2 5.0 5.8 .SIGMA. M [nH]
0.093 0.092 0.090 0.089 0.090 0.087 0.080 0.063 .fwdarw. 0.684
[0161] The first example explained above can be summarized as the
following:
[0162] That is, if the current change rate is 15 A/.mu.s, the open
end voltage will become 82 mV when the cross-section area of the
coil is 2 mm.sup.2 (2 mm.times.1 mm) and the coil has 64 turns. In
the case of a trial production coil form, by setting the
cross-section area of the trial production coil to 3.92 mm.sup.2
(inner diameter : 2.45 mm.times.1.6 mm) and by setting the turn
number to 48, about 1.47 times as much output will be obtained, and
the open end voltage of 120 mV will be obtained.
[0163] It is thought that 10-ohm terminal voltage at the time of
actual measurement will become about 105 mV if the inside
resistance of the coil is 1.47 ohms. This example is the analysis
where the bonding wires are approximated by the aluminum board S.
It turned out that the output voltage of the almost same order as
80 mVp of the measurement result obtained in the second example
explained in full detail behind is obtained. As long as the gain of
the integration circuit, and the noise of transmission from the
coil to the integration circuit are low enough, a resistance of
about 1ohm will be sufficient for the terminus resistance.
[0164] That is, from the result of the analysis, it has also been
confirmed that the current detection equipment of the invention can
be used as a chip current sensor.
SECOND EXAMPLE
[0165] Next, based on the analysis of the first example mentioned
above, concrete current detection equipment was made as a second
example of the invention, and the performance was evaluated. In
this example, the inventors have tried to measure the chip current
in the conventional module, without changing the bonding wires and
the modular structure. Specifically, a structure where the probe
part can sandwich the bonding wires from the circumference was
employed. Moreover, wires were not wound around a substrate but the
coil parts were realized by using the multilayered printed circuit
board in which the patterns were formed. Thus, reproducibility of
the measurement can be secured even if the total size of the
semiconductor device is miniaturized.
[0166] FIG. 27 is a schematic diagram showing the probe part of the
current detection equipment fabricated in this example. That is,
this probe part P has similar structure to what was mentioned above
about FIGS. 14A through 17.
[0167] FIG. 28 is a schematic diagram showing the coil section of a
probe part. These coils are connected so that the electromotive
powers which are induced in the upper and lower coil parts C may be
added. Since a magnetic flux is generated by the current which
flows through the bonding wire S, the coil detects this magnetic
flux and the voltage corresponding to the current is induced at a
coil.
[0168] FIGS. 29A through 29C are schematic diagrams showing the
more concrete structure of the probe part P. FIG. 29A shows a plan
view, FIG. 29B shows a front view, and FIG. 29C shows a side
view.
[0169] Here, the three-layered printed circuit board is used as the
substrates 10A and 10B. The coil is formed by the patterns 12 of
the both sides of the substrate and the through holes 14. The end
of the coil is connected to the inner layer of the substrate 10A,
and it is connected to the beginning of the coil of the substrate
10B. Connection of the upper and lower substrates 10A and 10B is
made by the sandwiched spacer 10C. Here, by laminating the coil
substrates 10A and 10B of the same structure, the common phase
rejection ratio against the noise by the external magnetic flux can
be improved, and the influence of voltage increasing rate dv/dt
generated at the time of current interception can be decreased. A
termination resistance (not shown) is connected to the patterns
(PTR).
[0170] Size of the substrates 10A and 10B of a probe part was made
into a width of 3.5 mm.times.length of 20 mm by taking the number
and pitch of the bonding wires which should be measured into
consideration. Moreover, the length of the insertion part
containing the bonding wires was made to 15 mm.
[0171] Moreover, substrate thickness (coil thickness) was set to
1.6 mm so that a coil cross-section area might be enlarged and
large output voltage might be obtained. Consequently, the
cross-section area of the coil was set to approximately 3
mm.times.1.6 mm. On the other hand, although the output voltage
decreases, the probe of 1 mm of basis board thickness (coil
thickness) was also fabricated so that a measurement might be
possible also in a narrower space.
[0172] Thickness of spacer 10C was set to 0.6 mm, in order to
insert a bonding wire of 0.3 mm .phi. and to make the detection
sensitivity not fall. The upper and lower substrates 10A and 10B
were pasted up through the spacer 10C, and were connected by
soldering the wire 18 which penetrated through the spacer 10c.
[0173] Moreover, in order to measure not only a bonding wires but
the current of the power bus (t=1 mm) in a module which was shown
in FIG. 18, the probe where the thickness of the spacer 10C was 1.6
mm was also fabricated.
[0174] Thus, when the fabricated probe part of the example is
compared with the conventional CT probe, weight was about {fraction
(1/60)} and volume was {fraction (1/22)}. That is, it turned out
that a weight saving and a miniaturization can be attained
sharply.
[0175] FIG. 30A shows the experimental setup. FIG. 30B is a
graphical representation showing the waveform when inserting a
copper plate in a probe part and passing pulse current. That is,
the characteristic A shows the current value measured with the
conventional CT type probe, B shows the output waveform from the
probe part of the invention where the oil thickness was set to 1.6
mm, C shows the output waveform from the probe part of the
invention where the coil thickness was set to 1 mm, and D and E
show the waveforms which were obtained by the integration
processing of the waveform of B and C, respectively.
[0176] As shown in FIG. 30B, also when the probe part of the
invention is used, the same current waveform as the conventional CT
type probe can be reproduced. Moreover, the difference in the coil
cross-section area produced here by the difference in the coil
thickness of 1 mm (C and E) and 1.6 mm (B and D) has induced the
difference of 1.6 times the output voltage. Since the current rate
of change was as slow as the di/dt=15 A/.mu.s, output voltage was
80 mVp.
[0177] Next, the inventors have investigated about change of the
output voltage by the position relation of the conductor S and the
probe part P.
[0178] FIG. 31 is a schematic diagram showing this measuring
method. Here, the copper plate of width 15 mm.times.0.5 mmt was
used as a conductor S through which the current I flows.
Differentiation output voltage was measured while changing the
position relation between the conductor S and the probe part P as
follows:
[0179] (1) With regard to the direction of the x-axis, the position
where the probe part P was inserted conductor S the deepest was set
to 0 mm, and while pulling out the conductor S gradually, the
relation of the position and the output voltage was measured.
[0180] (2) With regard to the direction of the Z-axis, the position
where the conductor S was inserted in the center of the interval of
the probe part P was set to a standard (0 mm), and the
differentiation output voltage was measured while making the
conductor S move to upward from the standard position.
[0181] FIGS. 32 and 33 are graphical representations showing these
measurement results. Here, the measurement position in the
horizontal axis expresses the interval of the center of the probe
part P, and the upper part of the conductor S.
[0182] About the direction of the X-axis, as expressed in FIG. 32,
the output voltage in the position (X=0) which the probe part P
inserted in conductor S most deeply is the maximum, and the output
voltage is decreasing almost linearly as the conductor S separates
from the probe part P. In the positions where the conductor S
separates 3 mm or more from the opening end of the probe part P,
output voltage decreases down to about 2.4 percent.
[0183] On the other hand, as for the direction of the Z-axis, if
the position becomes 2 mm or more, output voltage will fall almost
by an order, as expressed in FIG. 33. Here, that the position of
the conductor S is 2 mm or more means that the conductor S is
provided in the outside rather than that is inserted into the gap
of the substrates 10A and 10C of the probe part P. That is, a
position relation which was illustrated in FIGS. 20A and 20B is
formed. Thus, although the output declines, measurement of the
current is possible, even when the conductor S is placed in the
side of the probe part P, without being inserted into the probe
part P.
[0184] FIG. 34 is a graphical representation showing the relation
between current change rate di/dt and output voltage. Here, the
current change rate di/dt was measured up to 50 A/.mu.s. As a
result, it turned out that the current change rate and the output
voltage were maintaining the linear relation mostly, and thus, a
high measurement of accuracy could be obtained.
[0185] FIG. 35 is a graphical representation showing the
distribution of the relative measurement accuracy of two or more
probe parts. 20 probes parts were made as an experiment, and those
differentiation output voltages were measured. As a result, the
relative accuracy in the probe in the same conditions is less than
plus-or-minus 1 percent, and it became clear that the
reproducibility of sensitivity is very good.
[0186] In this example, the coaxial cable was used as a lead from
the probe part P so that a lead might not be affected, even if big
voltage change rate dv/dt occurred at the time of current
interception. As a coaxial cable, a super thin coaxial cable was
used whose tip size was 0.65 mm .phi. so that stress might not be
given to the bonding wire used as the measured body when the probe
part P moved. This super thin coaxial cable was connected to the
1.5 D-2V coaxial cable on the way, then connected with the BNC
connector. Moreover, in order to suppress vibration, the
termination was carried out by 10-ohm resistance for one coil.
[0187] Next, the current which flew a semiconductor element was
measured by carrying the probe part P in the module for electric
power control, as expressed in FIGS. 14A through 17. The output
waveform from them was observed by adding the probe parts P to four
DBC substrates of the 4.5 kV-600 A module which consists of 16
semiconductor chips.
[0188] Since the output signal from the probe part P is
differentiation output voltage, an original current waveform can be
reconstructed by using an integration circuit.
[0189] FIG. 36 is a circuit diagram showing the principal part of
the integration circuit used in this example. This integration
circuit performs an imperfect integration using the OP amplifier.
As the OP amplifier, the amplifier of the type of an FET input type
and a low drift broadband was adopted.
[0190] FIG. 37 is a graphical representation showing the waveform
which observed the current of 16 semiconductor chips.
[0191] FIG. 38A expresses the waveform adding the current
measurement data of 16 chips measured by the probe part of the
invention, and FIG. 38B is a graphical representation showing the
main current waveform measured with the conventional CT type
probe.
[0192] From these results, it is understood that by using the probe
part of the present invention, the current measurement is
successful and the same current waveform as the conventional CT
type probe is obtained for all the 16 semiconductor chips.
[0193] As mentioned above, as explained in full detail, in this
example, it turned out that the probe part included in the bonding
wire of 16 chips, all the addition current waveforms obtained with
the integration vessel and the main current waveform measured with
the conventional CT type probe are almost equivalent.
[0194] In the case where the current change rate di/dt=50 A/.mu.s,
differentiation output voltage is 330 mVp (terminated at 10 ohms to
each coil). Therefore, under the actual use condition where the
current change rate di/dt=100 A/.mu.s or more, the output voltage
becomes about 1 VolP. This voltage level is considered to be enough
as a signal output.
[0195] Moreover, the variation in the relative sensitivities of the
probe parts P is less than plus-or-minus 1 percent under the same
conditions, and thus, very good reproducibility was obtained. Also
about the influence of a wire frame, when separated from the basic
characteristic about 10 mm, the data which falls to 5 percent or
less was obtained, and influence was not seen by this evaluation,
either. It was checked that the current of a chip is measurable
including in a module, since it was such.
[0196] Although the preferred embodiment of the present invention
has been described heretofore, referring to its examples, it is not
intended that the invention should be limited to those
examples.
[0197] Configuration, size, shape, materials, arrangement of each
component of the current detection equipment and the semiconductor
device may be appropriately modified by any person skilled in the
art, and it will be appreciated that such modifications should all
be included in the scope of the present invention.
[0198] For example, the product which includes a protective film
etc. over the substrate so that the conductive patterns which
consist the coil may not expose is also included within the range
of the invention.
[0199] Moreover, the product where the coil is embedded inside is
also included within the range of the invention by laminating
another substrate etc. on the substrate on which the coil is
formed.
[0200] While the present invention has been disclosed in terms of
the embodiment in order to facilitate better understanding thereof,
it should be appreciated that the invention can be embodied in
various ways without departing from the principle of the invention.
Therefore, the invention should be understood to include all
possible embodiments and modification to the shown embodiments
which can be embodied without departing from the principle of the
invention as set forth in the appended claims.
* * * * *