JPH10294587A - Device for countermeasure against electromagnetic noise - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the shielding of a cable flux by a simple structure and a freely moving construction, and to suppress the influence of external noise by a method wherein conductive cloth is earthed to a ground plate and it is fixed to the ground plate together with the cable flux. SOLUTION: The electromagnetic wave noise from outside is introduced into a conductive cloth 42, and the noise bypasses a ground plate 20 from a cramping means through an auxiliary bar 21 and relieved. Since the grounding plate 20 is a large plate and the potential thereof is made equal to that of the ground of the main body of a semiconductor testing device, the energy of the bypassed electromagnetic waves is absorbed and hardly gives affection to other parts. As a result, when the relative prevention effect of the noise is measured by applying test voltage of test pulse, 1.3 kV is obtained when a countermeasure against the electromagnetic noise is taken by a ferrite core, the voltage becomes 2 kV or higher when there is an electromagnetic wave noise counter measure, and the preventing effect of the electromagnetic noise can be increaaed sharply.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic device, and more particularly to an electromagnetic noise suppression device for a cable bundle connecting a semiconductor test device and a peripheral device.

[0002]

2. Description of the Related Art An example of the prior art will be described with reference to FIGS. First, an environment in which an electronic device, particularly a semiconductor test device, requires a countermeasure against electromagnetic noise will be described. As shown in FIGS. 7 and 8, one example of the semiconductor test apparatus is a semiconductor test apparatus including a workstation 10 serving as an operation interface, and a power supply unit of each unit and apparatus for generating and testing a test signal. An apparatus main body 11, a device under test 14,
And test heads 12 and 13 which incorporate an electronic circuit serving as an interface with the test head 15.

Cables necessary for transmitting and receiving various kinds of voltage power supplies and signals are bundled between the semiconductor test apparatus main body 11 and the workstation 10 and between the semiconductor test apparatus main body 11 and the test heads 12 and 13, respectively. It is connected by a plurality of cable bundles 40, and the installation position is movable within the range of the length of the cable bundle 40.

For example, between the semiconductor test apparatus main body 11 and the test heads 12 and 13, four to ten cable bundles are connected with a length of about 3 m. Each of the cable bundles is, for example, a bundle of coaxial cables 43 for signal or a bundle of power supply cables as shown in FIG. The zipper tube 41 is a vinyl protection tube that can be easily covered with the zipper in a tubular shape.

The signals transmitted through each cable include a test pattern and a clock signal serving as a signal reference. These signals are apt to be affected by electromagnetic wave noise from the external environment in a cable bundle because the amplitude of the signal level has been reduced with the increase in speed.

Further, since the use environment in which the semiconductor test apparatus is installed is an industrial environment, it is susceptible to electromagnetic noise, and the test standards for the semiconductor test apparatus are stricter than those of general light industrial equipment.

For example, a line to which a voltage of 1 kV or more with a rise of 2 ns is applied as a test pulse is capacitively coupled in parallel with the cable bundle 40 to test for malfunction. Therefore, it is necessary to avoid the influence of the electromagnetic wave noise, and the countermeasure will be described below.

[0008] As shown in FIG.
Of the coaxial cable 43 and the ferrite core 61 for each terminal of the power cable 44 to prevent electromagnetic wave noise.
However, no sufficient effect of preventing noise was obtained by the above test method.

It should be noted that the peripheral device workstation 10
Also, since the test head needs to be able to be installed at any position, an apparatus or method having a structure in which the entire length of the cable bundle 40 is fixed and shielded by a shield plate cannot be implemented.

[0010]

As described above, between the semiconductor test apparatus main body and the workstation, and between the semiconductor test apparatus main body and the test head, a plurality of cable bundles necessary for transmission and reception of various types of power supply and signals are provided. And are susceptible to electromagnetic wave noise. However, the measures using a ferrite core are not sufficient in the effect of preventing electromagnetic wave noise, and have a practical difficulty. Accordingly, the present invention has been made in view of the above problems, and has as its object a simple configuration and a movable structure, which makes it possible to easily shield a cable bundle and is less susceptible to external noise. It is to provide a countermeasure device.

[0011]

That is, a first aspect of the present invention, which has been made to achieve the above object, is an electromagnetic wave noise countermeasure device for a cable bundle connecting between a main body of an electronic device and a peripheral device. A ground plate connected to the ground of the main body of the electronic device and disposed around the main body of the electronic device; a conductive cloth covering and shielding the cable bundle; and grounding the conductive cloth to the ground plate. And
The gist of the invention is an electromagnetic wave noise countermeasure device characterized by comprising a clamp means fixed to the ground plate together with the cable bundle to prevent the influence of electromagnetic wave noise.

Further, a second aspect of the present invention, which has been made to achieve the above object, is a gist of the electromagnetic noise suppression device according to the first aspect of the present invention, wherein the electronic device is a semiconductor test device.

Furthermore, a third aspect of the present invention, which has been made to achieve the above object, is an electromagnetic noise suppression device according to the first or second aspect of the present invention, wherein the shielding means is a conductive cloth.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described in the following examples.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a semiconductor test apparatus according to the present invention will be described with reference to FIGS. As shown in FIG. 2, the main components of the electromagnetic wave noise countermeasure device include a ground plate 20 connected to the semiconductor test device main body 11 by a ground ground cable 50, and a bundle of cables covered as shown in FIG. It comprises a conductive cloth 42 to be shielded, a clamp body 31 for fixing the cable bundle 40, and a clamp 33 for grounding the conductive cloth 42 to the ground plate 20. Hereinafter, each component and structure will be described.

The ground plate 20 is, for example, 300 ×
3 mm thick aluminum plate with a unit length of 900 mm.
As shown in (1), a screw hole is provided in the periphery so that it can be freely extended in a direction perpendicular to the length by being connected by a connecting bar 22 made of an aluminum plate.

The ground plate 20 and the ground of the semiconductor test apparatus main body 11 are connected to the ground ground cable 5.
Since they are connected by 0 and are plate-shaped planes, the whole is kept at a ground potential with low impedance.

Further, as shown in FIG.
An auxiliary bar 21 made of an aluminum plate is screwed to the ground plate 20 so that 1 can be easily fixed with the screw 35.

The conductive cloth 42 of the shielding means for covering and shielding the bundle of cables is made of an acrylic fiber base cloth plated with nickel and has a thickness of 0.2 mm.
It is cloth of degree. In addition, the conductive cloth 42 covers the outer periphery of the bundle of cables and has a large surface area. Therefore, the impedance per unit length of the conductive cloth itself is reduced, and the shielding effect is increased. As shown in FIG. 5, for example, a coaxial cable 43 is
Cover the bundle and shield the zipper tube 41
To protect it.

As shown in FIG. 4, the clamping means comprises, for example, a clamp body 31 and a clamp fitting 33.
The structure can be locked by the clamp claws 32 and the clamp grooves 34. The material of the clamping means is a conductive cloth 42.
Therefore, it is necessary to use a metal having conductivity and strength, for example, a stainless steel plate having a plate pressure of 1.5 mm. Further, the structure of the clamping means is shown as a structure in which locking can be easily performed with one touch, but a simple structure in which two semicircular plate-like metal fittings are used and fixed by screws may be used. Then, as shown in FIG. 1, the cable bundle is fixed by the clamp body 31, the conductive cloth 42 is sandwiched and locked by the clamp fitting 33, and is grounded to the ground plate 20 via the auxiliary bar 21. I have to.

Next, the operation of the electromagnetic wave noise suppression device of this embodiment will be described. Electromagnetic noise from the outside is guided by the conductive cloth 42 and is clamped by the auxiliary bar 21.
Through the ground plate 20 to escape. The energy of the bypassed electromagnetic noise is
Since the ground plate 20 is a large plate and has the same potential as the ground of the semiconductor test apparatus main body 11, it is absorbed and hardly affected by others.

As a result, when the relative prevention effect of noise was measured by applying the test voltage of the test pulse according to the test method described in the background art, it was 1.3 kV when the electromagnetic wave noise was prevented by the ferrite core. In the case where the electromagnetic wave noise countermeasure device is provided, the voltage is 2 kV or more, and the effect of preventing electromagnetic wave noise is greatly increased.

Although the coaxial cable is shown as a bundle of cables in this embodiment, the present invention can be similarly applied to a case where a power cable, a flat cable, a twisted wire, a knitted wire, or the like has no shield. . In addition, although the clamp body for fixing the cable bundle is screwed to the auxiliary bar, a structure in which the cable bundle is directly screwed to the ground plate can be similarly implemented. Although the method has been described in which the conductive cloth is sandwiched and locked between the clamp body and the clamp fitting, a method in which the conductive cloth is directly grounded to the ground plate by the clamp means can be similarly implemented. Further, although an example using a conductive cloth as the shielding means has been described, the present invention can be similarly implemented using a flexible mesh-shaped metal.

[0023]

The present invention is embodied in the form described above and has the following effects. That is,
The cable bundle is covered with a conductive cloth that is conductive, and the ground plate is grounded directly without using an electric wire with a clamp, so it is grounded with low impedance and electromagnetic noise can easily escape to the ground plate. , The effect of the shield increases. Therefore, with a simple configuration and a structure in which the peripheral device can be freely installed, the shield of the cable bundle can be reliably performed, and there is an effect that it is hardly affected by external noise. Further, since the electromagnetic wave noise countermeasure device of the present embodiment is not affected by external electromagnetic wave noise, the electromagnetic wave noise radiated from the cable bundle is also reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main part of an electromagnetic wave countermeasure device of the present invention.

FIG. 2 is a plan view in which the electromagnetic wave countermeasure device of the present invention is used in a semiconductor test device.

FIG. 3 is a diagram in which a clamp body is attached to a ground plate.

FIG. 4 is a diagram illustrating an example of a clamp.

FIG. 5 is a perspective view showing an example in which a cable bundle is shielded with a shielding cloth.

FIG. 6 is a perspective view showing an example of a cable bundle.

FIG. 7 is a perspective view showing an example of a semiconductor test device.

FIG. 8 is a plan view showing an example of a semiconductor test device.

FIG. 9 is a perspective view of a main part in which a conventional measure against electromagnetic waves is taken.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Workstation 11 Semiconductor test apparatus main body 12, 13 Test head 14, 15 Device under test 20 Ground plate 21 Auxiliary bar 22 Connection bar 31 Clamp main body 32 Clamp nail 33 Clamp fitting 34 Clamp groove 35 Screw 40 Cable bundle 41 Zipper tube 42 Conductivity Cloth 43 Coaxial cable 44 Power cable 50 Grounding cable

Claims (3)

[Claims] An electromagnetic wave noise suppression device for a cable bundle connecting between a main body of an electronic device and a peripheral device, wherein the device is connected to a ground of the main body of the electronic device and arranged around the main body of the electronic device. A ground plate, shield means for covering and shielding the cable bundle, and clamp means for grounding the shield means to the ground plate and fixing the shield means to the ground plate together with the cable bundle. Electromagnetic noise suppression device. 2. The electromagnetic noise suppression device according to claim 1, wherein the electronic device is a semiconductor test device. 3. The shielding means is a conductive cloth.
Or the electromagnetic wave noise suppression device according to 2.