JPH0528530Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention is designed to reduce the electrical overstress caused by electrostatic discharge to large-scale integrated circuits, integrated circuits, semiconductor elements, microstructured electronic components, and various electronic devices. The present invention also relates to an electrostatic discharge simulator that artificially generates electrostatic discharge in order to test and evaluate electromagnetic interference or the susceptibility to electrostatic discharge of the various electronic circuits, parts, equipment, etc. mentioned above.

(Prior Art) The electrostatic discharges to the various electronic circuits, parts, and equipment mentioned above are most often caused by electrostatic charges from charged objects made of conductors insulated from the earth, especially from the human body. Therefore, many conventional electrostatic discharge simulators use equivalent models of a charged human body.

Figure 5 is a diagram showing an example of a conventional electrostatic discharge simulator, where S _DC is a charging power source, SW _S is a power switch consisting of a relay switch, etc., SW _D is a switch for controlling the opening/closing of the relay switch SW _S , and S _D is the power supply for driving the relay switch SW _S , R _C is the charging resistor,
C _CD is a charge/discharge capacitor, R _D is a discharge resistor, SED is a discharge electrode, CAS _I is a casing made of insulating material, RGW
is the return wire (return ground wire), and one end of it is directly connected to the ground electrode side of the charging/discharging capacitor C _CD . GAP is the discharge gap, and EUT is the test object.

The charging voltage of the human body usually reaches from several kV to 10-odd kV, and in some cases it can reach up to 30-odd kV. Therefore, in the conventional electrostatic discharge simulator mentioned above, the output voltage of the charging power supply S _DC can be set to 0 V or more. 30 numbers
It is configured to be variable over a range of kV, so that the charging voltage of the charging/discharging capacitor C _CD can be set to various required values.

In addition, the capacitance of the charging/discharging capacitor C _CD and the resistance of the discharging resistor R _D are made equivalent to the capacitance and resistance of a charged human body, but the actual values of the capacitance and resistance of the human body vary over a fairly wide range. As a typical value, the equivalent capacitance of the charge/discharge capacitor C _CD is 50 pF.
250pF to 250pF, the equivalent resistance of discharge resistance R _D is 100Ω to
An appropriate fixed value is selected from each range of 1500Ω.

(Problem to be solved by the present invention) In the conventional electrostatic discharge simulator shown in Fig. 5, after charging the charging/discharging capacitor C _CD to the required voltage in advance, the tip of the return wire RGW is connected to the test object.
Connect it to the ground terminal of the EUT, etc., and gradually bring the discharge electrode closer to (or come into direct contact with) the EUT under test.
When the product of the length of the discharge gap GAP and the atmospheric pressure reaches a value corresponding to the charging voltage of the charge/discharge capacitor C _CD , the charge of the charge/discharge capacitor C _CD is instantaneously reduced by the spark discharge (or contact conduction). A charging/discharging capacitor C _CD is added to the EUT under test and is connected to the return line RGW.
Return to the ground electrode.

This return wire RGW usually uses a 1m to 2m conducting wire, but the inductance distributed in this return wire is determined not only according to the length and diameter of the return wire, but also the configuration of the return wire, that is, the return wire The distributed inductance of the retrace wire is determined by the relative electromagnetic environment between the retrace wire and the retrace wire, which is determined depending on the state of the retrace wire itself, such as whether it is drooping or under tension, and the surrounding conditions of the retrace wire. It varies over a range of approximately 1 μH to 2.5 μH. This change in distributed inductance not only changes the waveform of the discharge current, but also significantly changes the levels of the induced and radiated electromagnetic fields and modes such as TE, TM, and TEM. The disadvantage is that the electromagnetic interference effect on the body EUT fluctuates greatly, significantly impairing the reproducibility of discharge tests.

(Means and effects for solving the problems) In order to eliminate the above-mentioned conventional drawbacks, the present invention forms the housing with a conductor, and connects the ground side electrode of the charging/discharging capacitor to the human body of the operator and the human body through the housing. The waveform of the discharge current can be approximately The purpose is to realize an electrostatic discharge simulator with good reproducibility in discharge tests by keeping the level and mode of the induced electromagnetic field and the radiated electromagnetic field stable.

(Example) FIG. 1 is a sectional view showing an example of the present invention.
CAS _C is a housing made of a cylindrical conductor, SED is a discharge electrode, and the figure shows an example of a case made of a sphere.
It may also be formed using a needle-end electrode. ISN ₁ is an insulator and is interposed between one end of the housing CAS _C and the discharge electrode SED. TER is a connection terminal for a charging power supply circuit (not shown), and is fixedly attached to approximately the center of the insulating end wall INS ₂ fixed to the other end of the casing CAS _C. CSW is a wire or rod-shaped supporting conductor.
A terminal TER is fixed to one end, and a discharge electrode SED is fixed and attached to the other end via a discharge resistor R _D.
C _CD1 , C _CD2 , . . . are charging/discharging capacitors, each of which has one electrode fixed to the support conductor CSW, and each other electrode fixed to the inner wall of the casing CAS _C. RGW is a return wire, and one end of it is fixed to an appropriate location on the casing CAS _C made of a conductor.

In the proposed simulator as well, the combined capacitance of the discharging resistor R _D and the charging/discharging capacitors C _CD1 , C _CD2 , ... is set to a value corresponding to the human body resistance and human body capacitance, as in the conventional case.
That is, it is appropriately determined within the range of 100Ω to 1500Ω and 50pF to 250pF.

In the proposed simulator configured in this way, the charge/discharge capacitors C _CD , C _CD2 , ... are charged to the required voltage via the power supply connection terminal TER, and the return wire is
After connecting the tip of the RGW to the grounding terminal of the test object, a grounding point inside the housing wall, etc., or the grounding wire of the AC power line, hold the conductor housing CAS _C with your hand and connect the discharge electrode. When the test object is gradually approached (or brought into direct contact), a spark discharge occurs when the product of the length of the discharge gap and the atmospheric pressure reaches a value corresponding to the charging voltage of the charging/discharging capacitors C _CD1 , C _CD2 ,... (or contact continuity) to charge and discharge capacitors C _CD1 , C _CD2 ,...
A charge of ... is instantaneously applied to the test object.

Figure 2 is an equivalent circuit diagram under test conditions.
C _CDT is the combined capacitance of the charging and discharging capacitors C _CD1 , C _CD2 , ..., B is the human body, r is the human body resistance, C _ST is the stray capacitance existing between the human body B and the earth, and between the human body B and the test object EUT, L is the distributed inductance of the retrace line RGW, and the other symbols are the same as in FIG.

The high frequency discharge current applied to the EUT under test is
The charging/discharging capacitor is connected via the return wire RGW and the casing CAS _C (not shown in Figure 2) consisting of the conductor.
Most of the energy returns to the grounding electrodes of the charge/discharge capacitors C _CD1 , C _{CD2 ,} ... through stray capacitance C _{ST and} human body resistance r. becomes.

Fig. 3 is a diagram showing another embodiment of the present invention, in which a handle H made of a conductor is attached to a part of the case CAS _C made of a conductor pair, and a finger shape is attached to a part of the case as necessary. Providing corresponding unevenness. Other symbols and configurations are completely the same as in the previous embodiment.

When configured in this way, the handle H not only makes it extremely easy to hold and handle the simulator, but also ensures sufficient electrical contact between the housing and the human body to prevent quality deterioration of the return path due to contact resistance. I can do it.

(Effects of the present invention) In the present simulator, by forming the housing CAS _C with a conductor, it is possible to form a high-frequency current return path in parallel with the return line RGW through the human body operating it, and only the return line RGW can be formed. Unlike conventional simulators that form a return path using a return wire, there is no fear that the waveform of the discharge current will change depending on the configuration of the return wire. There is no fear of changing the mode, and the reproducibility of the discharge test can be made extremely good.

Figure 4 A shows the ideal waveform of the discharge current, B shows the waveform of the discharge current produced by a conventional simulator, and C shows the waveform of the discharge current produced by the simulator of the present invention. However, the waveform created by the proposed simulator is
The waveform is extremely close to the ideal waveform, demonstrating the remarkable effectiveness of the simulator of the present invention. In addition, in each figure,
The horizontal axis is the elapsed time t, and the vertical axis is the current i.

Also, in each figure, the discharge starting voltage is 1kV, the capacitance of the charging/discharging capacitor is 120pF, and the discharge resistance is 250Ω.The length of the return wire is 10cm for A, and 2m for both B and C. .

The CAS _C housing of the proposed simulator is made of a conductor and is held directly by hand, but during the discharge test it is grounded through the return wire RGW and the grounding wire of the test object, so there is no risk of danger to the human body. Not at all.

[Brief explanation of the drawing]

Figures 1 and 3 are diagrams showing one embodiment of the present invention, Figure 2 is an equivalent circuit diagram during a discharge test, Figure 4 is a waveform diagram of the discharge current, and Figure 5 is a conventional Diagram showing the electrostatic discharge simulator for CAS _C
...Housing, SED...Discharge electrode, INS ₁ and INS ₂ ...
…Insulator, TER…Charging power supply circuit connection terminal,
CSW...Support conductor, C _CD1 , C _CD2 ,...Charge/discharge capacitor, R _D ...Discharge resistor, RGW...Return wire, C _CDT
...Synthetic capacity, B...Human body, r...Human body resistance,
C _ST ... Stray capacitance, EUT... Test object, L... Distributed inductance, H... Handle, S _DC and S _D ...
Power supply, SW _S and SW _D ...switch, R _C ...charging resistor, C _CD ...charging/discharging capacitor, CAS _I ...housing, GAP...discharging gap.

Claims (1)

[Claims for Utility Model Registration] (1) A series circuit of a charging/discharging capacitor and a discharging resistor is housed in a casing made of a conductor, and a discharging electrode connected to the end of the series circuit on the discharging resistor side is connected to the casing. a charging power supply circuit connecting terminal connected to the charging/discharging capacitor side end of the series circuit is provided outside the housing while maintaining insulation from the housing; An electrostatic discharge simulator characterized in that one end of a return wire is connected to the casing. (2) The electrostatic discharge simulator according to claim 1, wherein a handle made of a conductor is protruded from a part of a casing made of a conductor.