Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
1999-06-23
2001-08-28
Brown, Glenn W. (Department: 2858)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
C324S263000, C324S750010
Reexamination Certificate
active
06281697
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device evaluation apparatus used for measuring current carried through the terminals of a semiconductor device, measuring noise leaking from a semiconductor device, evaluating a semiconductor device and such.
2. Description of the Related Art
Recently, as high-speed, high power consumption and highly integrated semiconductor devices are manufactured, demand for measuring high frequency noise outputted from the terminals of a semiconductor device rises. As an evaluation method for measuring high frequency noise and evaluating noise emission characteristics of a semiconductor device, there are proposed methods for operating a single semiconductor device and measuring noise thereof in IEC (International Electrotechnical Commission) as well as in US and European relevant industrial associations.
As a typical example of such evaluation methods, an evaluation method entitled “Electromagnetic Compatibility Measurement Procedures For Integrated Circuits-Integrated Circuit Radiated Emissions Measurement Procedure 150 kHz to 1000 MHz, TEM Cell” was made public in “IEC 47A/429/NP NEW WORK PROPOSAL, 1996.2”. In addition, an evaluation method entitled “Electromagnetic Emission (EME) Measurement of Integrated Circuits, DC to 1 GHz” was made public in “IEC 47A/428/NP NEW WORK ITEM PROPOSAL, 1996.2”. The former method is referred to as a first conventional method and the latter is referred to as a second conventional method, hereafter.
These evaluation methods are proposed specifications now under discussion in the IEC. In the methods, a semiconductor device is mounted on a test board, noise is measured and the noise emission characteristics of the semiconductor device is, thereby, inspected. The first conventional method is a typical example of measuring an electromagnetic field around the semiconductor device, whereas the second conventional method is a typical example of measuring noise leaking from the respective terminals of the semiconductor device.
Next, description will be given to the first conventional method.
FIG. 1
is a typical view showing the structure of an evaluation apparatus for use in the first conventional method.
FIG. 2
is a typical plan view showing a print-circuit board shown in FIG.
1
.
As shown in
FIG. 2
, a semiconductor device
1401
which serves as a DUT (Device Under Test) of an evaluation target, is mounted on the surface of a print-circuit board
1303
, which is referred to as a ‘test board’. A peripheral circuit (not shown) for operating the semiconductor device is formed on the back surface of the print-circuit board
1303
. A wiring pattern
1402
is formed at the surface of the print-circuit board
1303
. Each terminal
1404
of the semiconductor device
1401
is connected to the wiring pattern
1402
. The other end of the wiring pattern
1402
is connected to a via hole
1403
provided in the print-circuit board
1303
.
An opening portion is provided on the upper portion of a measuring unit
1301
, which is referred to as ‘TEM Cell’ (Transverse Electromagnetic Cell). As shown in
FIG. 1
, the print-circuit board
1303
is mounted in the opening portion. At this moment, the surface of the print-circuit board
1303
, on which the semiconductor device
1401
is mounted, is directed toward the measuring unit
1301
. One of the terminals of the measuring unit
1301
is terminated in a non-reflection manner by a terminating unit
1302
. A spectrum analyzer
1305
is connected to the other terminal of the measuring unit
1301
through a preamplifier
1304
. Then, while the influence of the peripheral circuit is being removed, the noise emitted from only the semiconductor device
1401
is measured as an electric field intensity by the spectrum analyzer
1305
.
There are proposed other evaluation methods for measuring emitted noise in the vicinity of the semiconductor device
1401
, as a DUT, as described above. Those methods are intended to measure the electromagnetic fields compounded in the vicinity of the semiconductor device as the intensity of the electromagnetic field and inspect the emission capability of the overall semiconductor device as in the case of the above-stated method using the measuring unit referred to as ‘TEM Cell’.
Next, description will be given to the second conventional method.
FIG. 3
is a typical view showing an evaluation apparatus for use in the second conventional method.
FIG. 4
is a typical cross-sectional view showing a POGO pin used in the second conventional method.
As shown, a semiconductor device
1501
, which serves as a DUT, is mounted on the surface of an IC test board
1505
consisting of a print-circuit board. A peripheral circuit (not shown) for operating the semiconductor device
1501
is formed on the back surface of the IC test board
1505
. The IC test board
1505
is attached to a main test board
1507
.
Micro-strip lines
1502
and
1504
are formed on the IC test board
1505
and the main test board
1507
, respectively. The micro-strip lines
1502
and
1504
are connected to each other through an impedance matching circuit
1503
. A receiver (electromagnetic measuring unit)
1508
is connected to the other end of the micro-strip line
1504
. An EMI (electromagnetic interference) receiver or a spectrum analyzer is utilized as the receiver
1508
. The receiver
1508
normally measures voltage generated by a load of 50 &OHgr;. Both of the test boards
1505
and
1507
are disc shaped and the micro-strip lines
1502
and
1504
radially extend from the centers of the test boards
1505
and
1507
, respectively.
Normally, the IC test board
1505
and the main test board
1507
are connected by means of a sliding component referred to as POGO pin shown FIG.
4
. The POGO pin is formed such that a pin contact
1602
can be slid in a socket
1601
by a spring
1603
, a plate spring
1604
and such.
Conductive noise generated at the respective pins of the semiconductor device
1501
, as a DUT, is measured by way of the micro-strip lines
1502
and
1504
.
However, the first conventional method has disadvantage in that emitted noises from the overall print-circuit board
1303
as a test board, the wiring pattern
1402
, the via hole
1403
and the terminal
1404
of the semiconductor device
1401
, as a DUT, cannot be distinguished from one another.
There are some cases where the emission of electromagnetic waves resulting from the overall structure of the print-circuit board
1303
as a test board is observed. Electromagnetic waves emitted from all of these emission elements are compounded and observed as emitted noise. This makes it extremely difficult to find one of many terminals
1404
provided at the semiconductor device that emits significant noise.
In addition, the first conventional method has a disadvantage in that using the intensity of an emitted electric field as an indicator for EMI noise preventive measures is difficult. The reason is as follows. The emission capability of the semiconductor device depends on various conditions including outside dimensions and shapes of chips and lead frames on the semiconductor device, the number of pins and such. Due to the dependency, it is required to take those conditions into account when carrying out the method. However, in the TEM Cell method for measuring noise emitted from the overall semiconductor device, it is almost impossible to give consideration to the conditions of those emission elements. As a result, measurement results obtained differ in the types of the evaluation target semiconductor devices, thereby making it extremely difficult to relatively inspect them based on the measurement results.
Meanwhile, the second conventional method has a disadvantage in that it is required to conduct tests in a state under impedance conditions and such for the respective micro-strip lines, terminal conditions different from those of the ordinary operating state. The reason is as follows. In the second conventional method, conductive noises generated at the respec
Masuda Norio
Tamaki Naoya
Brown Glenn W.
McGuireWoods LLP
NEC Corporation
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