JPH0435816Y2 - - 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. or electromagnetic interference or various circuits as mentioned above,
This invention relates to an electrostatic discharge simulator that artificially generates electrostatic discharge in order to test and evaluate the susceptibility of parts, various electronic devices, etc. to electrostatic discharge.

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

Figure 3 is a circuit diagram of the main parts of an example of a conventional electrostatic discharge simulator, where C _CD is a charging/discharging capacitor with a capacitance equivalent to that of a charged human body, and R _D is the resistance of a charged human body. SED is the discharge electrode, GAP is the discharge gap, and EUT is the test object.

The charging voltage of the human body usually ranges from several kV to a maximum of 30-odd kV, so a charging power supply circuit (not shown) is designed so that the charging voltage of the charging/discharging capacitor C _CD can be set in the range of OV to 30-odd kV. The equivalent capacitance of the charging/discharging capacitor C _CD and the equivalent resistance of the discharging resistor R _D are also determined according to the actual measured values of the human body, but since each value has a fairly wide range of variation, the representative Appropriate fixed values are selected from a range of 50 pF to 250 pF for the equivalent capacitance of the charging/discharging capacitor C _CD and 100 Ω to 1500 Ω for the equivalent resistance of the discharging resistor R _D.

After charging the charging/discharging capacitor C _CD in advance to the required voltage, when the discharging electrode SED is gradually brought closer to the EUT under test, the product of the length of the discharging gap GAP and the atmospheric pressure changes according to the charging voltage of the charging/discharging capacitor C _CD . The spark discharge that occurs when this value is reached causes the electric charge of the charging/discharging capacitor C _CD to be instantaneously applied to the EUT under test.

(Problem to be solved by the invention) In principle, the waveform of an electrostatic discharge current corresponds to an exponential curve, but due to causes specific to the spark discharge phenomenon in electrical discharge engineering, the actual waveform of the discharge current is The resulting waveform is quite different from the original waveform.

This kind of waveform change is due to the charging/discharging capacitor.
It has long been known that the voltage of C _CD depends on the change in the discharge starting voltage in the discharge gap GAP, but as a result of repeated discharge experiments using an electrostatic discharge simulator, the inventor of the present invention found the following. We were able to clarify that waveform changes occur due to various causes.

That is, when the electric charge of the charging/discharging capacitor C _CD is supplied to the discharge gap GAP, the conductivity of the spark space increases in the initial stage, and in the rising process, a part of the electric charge of the charging/discharging capacitor C _CD is lost in the spark space. During the spark discharge generation process, the electric field strength in the spark space decreases, and this decrease in electric field strength weakens the effect of increasing conductivity, causing the conductivity to increase along the trajectory corresponding to the original rise time. is no longer performed, and the rise time of the discharge current becomes shorter than the discharge gap.
There is a significant delay compared to the fixed time determined depending on the length of the GAP and the atmospheric pressure, and as a result, the waveform of the discharge current is distorted, reducing the reliability of the discharge test.

(Means and actions for solving the problem) In the discharge gap GAP between the discharge electrode SED of the electrostatic discharge simulator shown in Fig. 3 and the discharge electrode formed by a part of the EUT under test. There is a stray capacitance of about 1 pF to several PF depending on the surface area of the discharge electrode and the length of the discharge gap GAP.
At the beginning of spark discharge generation, the charge on the stray capacitance quickly disappears in the spark space, so the existence of the stray capacitance can be almost ignored. However, if the size of the stray capacitance is intentionally increased, the following operation occurs. It should be done.

That is, at the beginning of the spark discharge in the discharge gap GAP, the charge of the charge/discharge capacitor C _CD tries to be injected into the spark space via the discharge resistance R _D , but due to the discharge resistance R _D and the spark resistance in the discharge gap GAP, The amount of charge that is limited and injected into the spark space is extremely small.

However, since the charge of the stray capacitance is limited only by the spark resistance in the discharge gap GAP, regardless of the discharge resistance R _D , the amount of charge injected from the stray capacitance into the spark space is equal to the charge/discharge capacitor C C _D
The amount of charge injected from the spark gap is much larger than that of the spark, and as the conductivity in the discharge gap GAP increases, all of the charge in the stray capacitance is injected only into the spark space.

By reducing the impedance of the current path connecting the stray capacitance and the discharge gap GAP, charge can be quickly injected from the stray capacitance into the spark space, and most of the charge in the charge/discharge capacitor C _CD is lost. By flashing the discharge gap GAP without causing any damage, almost all of the charge in the charging/discharging capacitor C _CD can be applied to the EUT under test.

The energy applied to the EUT under test is
It is determined only by the current discharged from the charge/discharge capacitor C _CD through the discharge gap GAP, and is independent of the charge of stray capacitance.

This invention connects a capacitance element in parallel with the discharge gap in order to intentionally increase the stray capacitance existing in the discharge gap, and also reduces the impedance of the current path connecting this parallel capacitance element and the discharge gap. By making this extremely small, distortion of the waveform of the discharge current and Electrostatic discharge that can significantly improve electrical characteristics such as the rise time of discharge current compared to conventional ones, and that can minimize variations in the electrical characteristics that occur from discharge to discharge due to uncertainty in the spark generation mechanism. The purpose is to realize a simulator.

FIG. 1 is a diagram showing the main parts of an embodiment of the present invention, in which BED ₁ and BED ₂ are flanged counter electrodes, SED ₁ and
SED ₂ is a discharge electrode, and CMF ₁ and CMF ₂ are connection fittings, each made of a conductor with elasticity. In the case of the connecting metal fitting CMF ₁ , the contact piece is provided to protrude radially, and in the case of the connecting metal fitting CMF 1, the contact piece is bent diagonally downward, and its end is pressed against the upper surface of the inner periphery of the brim-shaped counter electrode BED _{1 .}
In this case, the end of the contact piece is a flanged counter electrode BED ₂
It is formed so as to be pressed against the lower surface of the inner periphery. The diameter of the hole drilled in the center of each of the connecting fittings CMF ₁ and CMF ₂ is the same as that of the discharge electrodes SED ₁ and CMF 2.
Make the diameter of each discharge electrode appropriately smaller than that of SED ₂ .
SED ₁ and SED ₂ are formed so as to be pressed against the inner peripheral edge of the connecting fittings CMF ₁ and CMF ₂ without passing through the openings. Although FIG. 2 shows an example in which four contact pieces are provided protrudingly, any number of three or more contact pieces may be provided protrudingly. SUP ₁ is an insulating support made of a suitable hard synthetic resin, etc., and is interposed in the opposing gap between the brim-shaped counter electrodes BED ₁ and BED ₂ .
The outer peripheries of BED ₁ and BED ₂ are sealed.

In addition, in order to prevent creeping discharge from each inner periphery of the brim-shaped counter electrodes BED ₁ and BED ₂ , it is desirable to cover each inner periphery with an insulator.

SUP ₂ is an almost cylindrical insulating support, with an insulating support
It is made of the same material as SUP ₁ , and its brim-like protruding part is integrally connected to insulating support SUP ₁ by means such as screwing or using a suitable adhesive, and the hollow part of cylindrical insulating support SUP ₂ is Internal and insulating support SUP ₁
The holes are formed in such a way that they communicate with each other.
SUP ₃ also has an approximately cylindrical insulating support;
It is made of the same material as SUP ₁ , and its brim-like protruding part is integrally connected to insulating support SUP ₁ by means such as screwing or using a suitable adhesive, and is attached to cylindrical insulating support SUP _3. screw hole and insulating support
It is formed so that it communicates with the hole drilled in SUP ₁ .

FS is a discharge gap adjustment element, which consists of a feed screw mechanism used in micrometers, etc., and can move the movable shaft forward or backward by rotating the rotation control knob in the forward or reverse direction, and can also move the movable shaft. It is formed so that the distance can be indicated by a scale, and is firmly fitted into the hollow interior of the cylindrical insulating support SUP ₂ , and a tightening ring is attached to the outer periphery of the cylindrical insulating support SUP ₂ , or a suitable It is fixedly attached to a cylindrical insulating support SUP ₂ by using adhesive or a set screw, and a discharge electrode SED ₁ is fixed to the inner end of its movable shaft. ZS is a zero adjustment screw, which is screwed into a screw hole provided in the cylindrical insulating support SUP ₃ , and the discharge electrode SED ₂ is fixedly supported at the inner end thereof. IS is an insulating screw that is screwed into a screw hole provided in the cylindrical insulating support SUP ₃ to prevent the top of the zero adjustment screw ZS from being directly exposed to the outside.

The center axis of the discharge gap adjustment element FS, the line connecting the centers of the discharge electrodes SED ₁ and SED ₂ , and the center axis of the zero adjustment screw ZS are formed so as to form one axis or almost one axis.

The CTT is a contact made of a rod-shaped conductor with a sharp tip and a rear end screwed into a screw hole provided from the outer circumferential surface of the insulating support SUP ₁ toward the center.
The counter electrode BED ₁ is firmly inserted and has a brim-like rear end surface.
It is fixed to the periphery of the (ground side electrode) so that it is crimped and electrically connected. HOL is an insulated holding tube,
Firmly fit the peripheral part of the insulating support SUP ₁ into the hole provided at the front end, and use adhesive or set screws as necessary to connect the insulating support cylinder HOL and the insulating support.
The insulating support SUP ₁ is integrated with SUP ₁ and inserted into the hollow interior of the insulating holding cylinder HOL.
A part of the peripheral part of the brim-shaped counter electrode BED ₂ is cut out
A part of the periphery of the insulation holding cylinder HOL is exposed to the hollow interior of the insulation holding cylinder HOL, or the end of the leader wire connected to the brim-like counter electrode BED ₂ is drawn out into the hollow inside of the insulation holding cylinder HOL.

In addition, when joining the insulating support SUP ₁ and the insulating holding tube HOL together, the discharge test was carried out by making the center axis direction of the contactor CTT almost coincide with the central axis direction of the insulating holding tube HOL. This makes it easier to handle the time.

Although not shown in the figure, a charging/discharging capacitor and a discharging resistor are installed inside the hollow interior of the insulating holding cylinder HOL, and a connecting wire to the charging power supply circuit is introduced from the rear end or side wall of the insulating holding cylinder HOL, Connect the high potential side electrode of the charge/discharge capacitor to the flanged counter electrode BED ₂ (high voltage side electrode) via the discharge resistor,
Connect to the high potential side of the connection wire to the charging power supply circuit, connect the low potential side electrode of the charge/discharge capacitor to the low potential side of the connection wire to the charging power supply circuit, and , connect an appropriate high resistance between an appropriate location of the discharge gap adjustment element FS or a location electrically connected to the brim-shaped counter electrode BED ₁ (ground side electrode) and the ground, such as a contactor CTT.

In the electrostatic discharge simulator of the present invention configured in this way, the knob of the discharge gap adjustment element FS is operated to match the scale as in the example, and the zero adjustment screw is adjusted.
After performing zero adjustment by rotating ZS and bringing the discharge electrodes SED ₁ and SED ₂ into close contact with each other, screw the insulating screw IS on, and then adjust the discharge gap by reading the scale while operating the knob of the adjustment element FS. Adjust to the required length. To check whether the discharge electrodes SED ₁ and SED ₂ are in close contact, for example, keep the charging power supply circuit open and check the continuity between the zero adjustment screw ZS and the adjustment element FS or between the contact CTT using a circuit tester, etc. Detect by tilting.

Also, when the knob of the adjustment element FS is rotated, for example, in the positive direction, the movable shaft moves forward, and the connection fitting CMF ₁
The discharge electrode SED ₁ is moved forward against the elasticity of the
If the knob is rotated in the opposite direction, the movable shaft will move back, and the discharge electrode SED ₁ will move back.
By rotating the knob in forward and reverse directions, the length of the discharge gap can be adjusted.

When the discharge electrode SED ₁ or SED ₂ moves forward, the connection fitting CMF ₁ or CMF ₂ is pressed, and the end of the contact piece protruding radially from the periphery connects to the flanged counter electrode.
It slides in the radial direction while being pressed against the surface of BED ₁ or SED ₂ , and the posture of the connection fitting CMF ₁ or CMF ₂ is lowered, so that it does not impede the forward movement of discharge electrode SED ₁ or SED ₂ , and vice versa. , discharge electrode SED ₁ or
If SED ₂ is retracted, connect fitting CMF ₁ or
Since CMF ₂ recovers due to each elasticity and becomes higher in posture, the flange-shaped counter electrode BED ₁ or BED ₂ and the discharge electrode
There is no possibility that the electrical connection between SED ₁ or SED ₂ will be broken.

After adjusting the length of the discharge gap to the required value, the contact
When a charging/discharging capacitor is charged by bringing the tip of the CTT into contact with a desired location on the test object, discharging occurs when the charging voltage reaches a voltage corresponding to the length of the discharge gap.

(Effect of the invention) In the electrostatic discharge simulator of the present invention, a capacitance in parallel with the discharge gap is formed by the flanged counter electrodes BED ₁ and BED ₂ , and this parallel capacitance and the discharge gap are connected to the connecting metal fittings CMF ₁ and CMF. ₂ and are connected by discharge electrodes SED ₁ and SED ₂ ,
The impedance at this connection is extremely small.

When charging the charge/discharge capacitor, when charging the charge/discharge capacitor with the contactor CTT in contact with the test object in advance, the insulating holding tube
Discharge resistor built into HOL, flanged counter electrode BED ₂
A parallel capacitor consisting of _{the flanged counter electrodes BED 1 and} BED ₂ is charged together with the charge/discharge capacitor through the contact CTT and the test object, and the contact
When charging the charging/discharging capacitor without bringing the CTT into contact with the test object, connect it electrically to the flanged counter electrode BED ₁ at appropriate points on the discharge gap adjustment element FS or at the contactor CTT, etc. High resistance and insulation holding tube HOL inserted between the location and the ground air
A flanged counter electrode is connected through a discharge resistor built into the
The parallel capacitance consisting of BED ₁ and BED ₂ is also charged,
When the charge/discharge capacitor is discharged, a large amount of charge from the parallel capacitor is quickly injected into the spark space, causing the discharge gap to flash without losing much of the charge/discharge capacitor's charge. According to the results of experiments conducted by changing the capacitance of the charge/discharge capacitor, the resistance value of the discharge resistor, the length of the discharge gap, etc., it was found that the rise time and It was confirmed that the electrical characteristics such as waveform distortion were significantly improved compared to the conventional method, and that the variation in the electrical characteristics between discharges was also extremely small.

In addition, if the resistance value of the high resistance provided for charging the parallel capacitance consisting of the brim-shaped counter electrodes BED ₁ and BED ₂ is made appropriately larger than the impedance of the test object, the discharge current will be increased by this high resistance. There is no risk of the flow being diverted to

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 is a plan view showing an example of the structure of its component parts, and Fig. 3 is a diagram showing an example of a conventional electrostatic discharge simulator. ₁ and BED ₂ ...flange-shaped counter electrode,
SED ₁ and SED ₂ ...Discharge electrode, CMF ₁ and CMF ₂
... Connection fittings, SUP ₁ to SUP ₃ ... Insulating support,
FS...discharge gap adjustment element, ZS...zero adjustment screw, IS...insulation screw, CTT...contact, HOL
...Insulation holding cylinder, C _CD ...Charging and discharging capacitor, R _D
...discharge resistance, SED...discharge electrode, GAP...discharge gap, EUT...test object.

Claims (1)

[Scope of utility model registration request] First and second flanged counter electrodes facing each other at an appropriate interval, and first and second discharges facing each other through a hole in the center of each of the first and second flanged opposing electrodes. a first connecting fitting made of a conductor having elasticity and interposed between the electrode, the first flanged counter electrode and the first discharge electrode and pressed against both electrodes; and the second flanged electrode. A second connecting fitting made of a conductor having elasticity is interposed between the counter electrode and the second discharge electrode and is brought into pressure contact with both electrodes; The first discharge electrode is supported by an insulating support provided on the outer periphery of each of the first and second discharge electrodes, and the first discharge electrode is supported by the inner end of a movable shaft, and the axial direction is aligned with the center of each of the first and second discharge electrodes. a discharge gap adjustment element comprising a feed screw mechanism supported by the insulating support body in a direction substantially aligned with the direction in which the second
a zero adjustment screw screwed onto the insulating support, a contact made of a conductor connected to the first flanged opposing electrode, and the second flanged electrode via a discharge resistor. 1. An electrostatic discharge simulator comprising: a charging/discharging capacitor connected to a shaped counter electrode; and an insulating holding tube attached to the insulating support.