JPH0528531Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention deals with 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 the various electronic circuits mentioned above,
This invention relates to an electrostatic discharge simulator that artificially generates electrostatic discharge in order to test and evaluate the sensitivity of parts, equipment, etc. to electrostatic discharge.

(Problems to be solved by conventional techniques and inventions) Electrostatic discharge to various electronic circuits, parts, equipment, etc. as described above is due to the electrostatic charge of a charged body made of a conductor insulated from the earth, especially the human body. Most conventional electrostatic discharge simulators use an equivalent model of a charged human body.

FIG. 11 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 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 housing made of insulating material, RGW
is the return wire (return ground wire), one end of which is directly connected to the ground electrode 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 charge/discharge capacitor C _CD and the resistance value of the discharge resistor R _D are made equivalent to the capacitance and resistance of a charged human body, but the actual measured values of the capacitance and resistance of the human body vary widely. As a typical value, the equivalent capacitance of the charge/discharge capacitor C _CD is
50pF to 250pF, equivalent resistance of discharge resistance R _D is 100Ω
An appropriate fixed value is selected from each range from 1500Ω to 1500Ω.

In this conventional electrostatic discharge simulator, the charge/discharge capacitor _CCD is charged to a required voltage in advance, and then the tip of the return wire RGW is connected to the ground terminal of the EUT under test, and the discharge electrode SED is gradually brought closer to (or into direct contact with) the EUT under test. When the product of the length of the discharge gap GAP and the air pressure reaches a value corresponding to the charging voltage of the charge/discharge capacitor _CCD , a spark discharge (or contact conduction) occurs between the discharge electrode SED and the EUT under test, and the charge of the charge/discharge capacitor _CCD is instantaneously applied to the EUT under test, and the return wire
It returns to the ground electrode of the charge/discharge capacitor _CCD via RGW.

The return line RGW in the conventional electrostatic discharge simulator shown in Figure 11 normally uses a 1m to 2m conductor, but the inductance distributed in this return line RGW is determined depending on the length and diameter of the return line RGW. In addition to the condition of the return line RGW itself, such as the installation shape of the return line RGW, i.e., whether the return line RGW is in a drooping state or maintained in a taut state, the surrounding situation of the return line RGW is The distributed inductance of the return line RGW is approximately 1μH due to the relative electromagnetic environment between the return line RGW and the return line RGW, which is determined according to
It varies over a range of 2.5μH to 2.5μH. This change in distributed inductance not only changes the waveform of the discharge current, but also changes the level of the induced electromagnetic field and the radiated electromagnetic field induced in the space around the discharge circuit, TE,
Each mode such as TM., TEM, etc. is changed significantly, and as a result, the electromagnetic interference effect on the EUT under test varies greatly, which has the disadvantage that the reproducibility of the discharge test is significantly impaired.

In order to eliminate such drawbacks, the present inventor proposed an electrostatic discharge simulator whose cross section is shown in FIG. 3.

In Figure 3, CAS _C is a housing made of a housing-like conductor;
SED is a discharge electrode consisting of a spherical or needle-shaped electrode.
INS ₁ is an insulator interposed between one end of the casing CAS _C and the discharge electrode SED, T _S is a connection terminal for the charging power circuit, and the insulating end wall INS ₂ is fixed to the other end of the casing CAS _C.
It is fixedly installed almost in the center of the Although the charging power supply circuit is not shown, for example, the 11th
A circuit similar to that shown in the figure, i.e. a charging power supply
It consists of a circuit including S _DC , a power switch SW _S , a switch SW _D for controlling opening/closing thereof, a power source _SD for driving the power switch SW _S , and a charging resistor _RC . CSW
is a wire or rod-shaped support conductor, with a terminal T _S fixed to one end and a discharge electrode SED connected to the other end via a discharge resistor R _D.
is fixed and installed. C _CD1 , C _CD2 , ... are charge/discharge capacitors, each with one electrode connected to the supporting conductor.
CSW, and each other electrode is connected to the inner wall of the housing CAS _C. R _B is a buffer resistor, and RGW is a return wire, one end of which is fixedly connected to an appropriate location on the casing CAS _C made of a conductor.

In this electrostatic discharge simulator, the charging/ _discharging capacitor C _CD1 ,
After charging C _CD2 ,... to the required voltage and connecting the tip of the return wire RGW to the ground terminal of the test object, hold the conductor casing CAS _C by hand and gradually introduce the discharge electrode SED into the test object. When brought close to (or in direct contact with) the body, the product of the length of the discharge gap and the atmospheric pressure between the discharge electrode SED and the body under test is the charge/discharge capacitor C _CD1 , C _CD2 ,...
A charging/discharging capacitor is charged and discharged by a spark discharge (or contact conduction) that occurs when the charging voltage of
Charges C _CD1 , C _CD2 , ... are instantaneously applied to the test object.

Figure 8 is an equivalent circuit diagram of the above electrostatic discharge simulator under test conditions, where C _CDT is the combined capacitance of charge/discharge capacitors C _CD1 , C _CD2 , ..., B is the human body, and r
is the human body resistance, C _STB is the stray capacitance that exists between human body B and the earth, and between human body B and the EUT under test, and L is the return line.
This is the distributed inductance of RGW, and the other symbols are the same as in FIG. 3.

In this electrostatic discharge simulator, the housing
CAS _C is formed of a conductor, and the ground side electrodes of the charging/discharging capacitors C _CD1 , C _CD2 , ... and the return wire RGW are connected through this casing CAS _C , as shown in Figure 8. In addition, a return path for the high frequency current is formed in parallel with the return line RGW via the stray capacitance C _STB and the human body resistance r between the human body B and the earth and between the human body B and the EUT under test.

Therefore, the high-frequency discharge current applied to the EUT under test is transmitted through the return wire RGW and the casing made of the conductor.
It returns to the ground side electrode of the charging/discharging capacitors C _CD1 , C _CD2 , ... via CAS _C (not shown in Figure 8), but most of the energy is charged via stray capacitance C _STB and human body resistance r Discharge capacitor C _CD1 , C _CD2 ,...
Since the return wire RGW returns to the ground side electrode of
Compared to the electrostatic discharge simulator shown in Fig. 11 in which the return path is formed only by the return line RGW, the waveform change of the discharge current, the level of the induced electromagnetic field and the radiated electromagnetic field, and each of TE, TM, and TEM due to the installation shape of the return line RGW. It is possible to reduce mode changes and the like and improve the reproducibility of discharge tests.

Also, during discharge, the potential of terminal T _S decreases rapidly,
With this potential change, electromagnetic energy is radiated from the connection wire between the terminal T _S and the charging power supply circuit, which may cause an error in the discharge test results _.
By the buffer resistor R _B interposed between the support conductor CSW and the supporting conductor CSW, the radiation of electromagnetic energy as described above can be suppressed.

However, the stray capacitance C _STB between the human body B and the EUT under test changes depending on the individual differences in the human body B and the relative mechanical relationship between the human body B and the EUT under test.
The stray capacitance C _STB between the human body B and the ground air also varies depending on the individual differences in the human body B and the relative relationship of the human body B with the floor, etc., and the human body resistance r also varies among individuals, and these are the causes of discharge. This causes a change in the current waveform, which impedes the reproducibility of the discharge test.

The object of the present invention is to realize an electrostatic discharge simulator that can eliminate not only the drawbacks of the electrostatic discharge simulator shown in FIG. 11 but also the drawbacks of the electrostatic discharge simulator shown in FIG.

(Means for solving problems, embodiments) Fig. 1 is a side view showing an embodiment of the present invention, Fig. 2 is a front view thereof, and in both figures, PLN is made of a suitable metal material. A support plate having an L-shaped cross section,
HOD is a support tube made of a suitable metal material, and the flange FL provided at one end of the HOD is either welded to the periphery of an insertion hole drilled in a part of the vertical part of the support plate PLN, or bolted as shown in the figure. It is detachably attached using BT and nut NT. PRB is a charge/discharge probe, for example, the charge/discharge probe shown in Fig. 3, that is, a housing CAS _C made of a cylindrical conductor, a discharge electrode SED made of a spherical or needle-shaped electrode, an insulator INS ₁ , and
INS ₂ , charging power supply circuit connection terminal T _S , support conductor
CSW, buffer resistance R _B , discharge resistance R _D set to an appropriate value within the range of 100Ω to 1500Ω, combined capacitance set to an appropriate value within the range of 50 pF to 250 pF, and each ground side electrode is connected to the housing CAS _C It consists of a charging/discharging probe consisting of charging/discharging capacitors C _CD1 , C _CD2 , ... connected to the casing CAS C, return wire RGW, etc. connected to the casing CAS _C at one end.

In addition, the inner diameters of the insertion hole drilled in a part of the vertical part of the support plate PLN and the support tube HOD are made larger than the outer diameter of the charge/discharge probe PRB as appropriate.
The charge/discharge probe PRB is formed so as to be able to slide in the axial direction of the support tube HOD while maintaining electrical contact between the housing of the charge/discharge probe PRB and the support tube HOD, and the lower horizontal portion of the support plate PLN is attached to a screw. Either fix it to the floor or a suitable support by means such as a stopper, or increase the width of the horizontal part appropriately, and if necessary, install a horizontal part on the left side when facing the drawing to secure the whole support plate PLN. is formed into an inverted T-shape so that it can stand on its own by simply placing it on the floor or the like.

In the electrostatic discharge simulator of the present invention configured as described above, the test object EUT is fixed at a location opposite to the support plate _PLN , and the charging/discharging capacitors C _CD1 , C _CD2 ,... …
After charging the return wire RGW to the required voltage and connecting the tip of the return wire RGW to the grounding terminal T _G of the EUT under test, a grounding point inside the housing wall, etc., or a grounding wire in the AC power line, Charge/discharge probe supported by tube HOD
When the PRB is gradually slid forward and the discharge electrode SED approaches (or comes into direct contact with) the EUT under test,
The distance between the discharge electrode SED and the EUT under test, i.e.
The product of discharge gap length and atmospheric pressure is the charge/discharge capacitor.
Spark discharge (or contact conduction) that occurs in the discharge gap when C _CD1 , C _CD2 , ... reaches a value depending on the charging voltage
As a result, the electric charges of the charging/discharging capacitors C _CD1 , C _CD2 , ... are instantaneously applied to the EUT under test.

The above example uses a charge/discharge probe PRB in which the charge/discharge capacitor is formed using a lumped constant type capacitor. The present invention can also be implemented using a probe.

In Fig. 4, INS ₃ is a cylindrical insulator, TED ₁ is a cylindrical electrode, which is fixed to the inner surface of the cylindrical insulator INS ₃ ,
Electrode the end wall TED _E on its front edge (or rear edge)
It is provided integrally with TED ₁ , and the supporting conductor CSW is inserted and fixed into the insertion hole bored in the center thereof, and the supporting conductor CSW and the cylindrical electrode TED ₁ are electrically connected through the end wall TED _E. TED ₂ is a cylindrical electrode fixed to the outer surface of the cylindrical insulator INS ₃ , and the inner and outer cylindrical electrodes TED ₁ and
A distributed constant charge/discharge capacitor is formed by TED ₂ . Other symbols are the same as in FIG. 3.

This charge/discharge probe differs from the charge/discharge probe shown in Figure 3 only in that the charge/discharge capacitor is formed by a distributed constant type capacitor, and the external cylindrical electrode TED ₂ also serves as a casing made of a conductor. is exactly the same as that shown in the third figure.

As shown in Figures 3 and 4, the charging/discharging capacitor is configured such that the ground side electrode forming the charging/discharging capacitor is electrically connected to the support plate PLN through a casing made of a conductor or directly to the support plate PLN. The present invention can be implemented using a charging/discharging probe having a configuration other than that shown in FIG. 3 or 4 as long as it is a probe.

Regardless of the configuration of the charge/discharge probe, the cross-sectional shape of the charge/discharge probe is the same as that of the support plate PLN.
Although it is most desirable to form the support tube HOD into a circular shape in order to be able to slide finely within the support tube HOD attached to the HOD, the present invention can also be implemented by forming the support tube into any cross-sectional shape such as a rectangle.

In addition, the charge/discharge probe is installed inside the support tube HOD.
In order to facilitate the operation of finely sliding the PRB, a housing made of the conductor of the charge/discharge probe PRB is installed, as shown in the rear view of the main part in Figure 5.
Handles _H1 and _H2 are provided to protrude left and right on the rear side of CAS _C or external cylindrical electrode _TED2 , but handle _H3 may be provided to protrude downward as shown in the side view in Fig. 6. .

If the outer diameter of the charge/discharge probe PRB varies depending on the dimensions and shape of the internal parts of the charge/discharge probe PRB, a support plate with a support tube HOD attached that has an inner diameter that corresponds to the outer diameter of the charge/discharge probe PRB.
Various types of PLN may be prepared, or support tubes HOD with different inner diameters may be attached to a common support plate PLN by replacing them. The cross-section arc-shaped opposing piece HOD ₁
and a flange formed with HOD ₂ and provided on each opposing piece.
The bolt insertion holes LH drilled in FL ₁ and FL ₂ are formed to be elongated, and the opposing gaps between the opposing pieces HOD ₁ and HOD ₂ are changed so that it can be commonly used for charging/discharging probe PRB of various outside diameters. Good too. In this case, the respective flanges FL ₁ and HOD ₂ of the opposing pieces HOD ₁ and HOD 2
Instead of forming an elongated insertion hole in FL ₂ , a charge/discharge probe is drilled in the vertical part of the support plate PLN.
Of course, the insertion hole for the bolt drilled around the insertion hole HOL of the PRB may be formed in a long and narrow manner.

(Effect of the invention) Figure 9 is an equivalent circuit diagram of the proposed electrostatic discharge simulator under test conditions, where PLN is the support plate, C _STP
is between the support plate PLN and the EUT under test, and between the support plate PLN
The other symbols are the same as in Fig. 8.

As is clear from FIG. 9, in the electrostatic discharge simulator of the present invention, the return path of the high-frequency discharge current is formed by the return wire RGW, and in parallel with this, the return path is formed between the support plate PLN and the ground air, and between the support plate PLN. Stray capacitance C _STP and support plate between EUT under test
A return path consisting of PLN is formed, and this return path does not include the human body resistance r in the equivalent circuit of FIG. 8 at all, and also increases the area of the support plate PLN.
By reducing the distance between the support plate PLN and the EUT under test, the stray capacitance can be increased.
The impedance of the parallel return path can be made smaller than in the case of FIG. 8, and the stray capacitance can always be kept almost constant. Therefore, most of the discharge energy returns to the ground side electrode of the charge/discharge capacitor via the return path on the support plate PLN side,
Since disturbances in the waveform of the discharge current can be suppressed and the test conditions can always be kept constant, the reproducibility of the test results is also good.

Ideally, the width and height of the vertical portion of the support plate PLN should be such that the body of the operator of the proposed electrostatic discharge simulator is completely shielded from the EUT under test, and the distance between the EUT under test and the operator is The support plate should be selected so as not to create stray capacitance between the
It is desirable to increase the area of the horizontal part of the PLN to maximize the floating capacity between it and the ground air, but according to experimental results using a prototype machine,
Practically satisfactory results were obtained by selecting the area of the vertical portion of the support plate PLN to such an extent that the handler was almost shielded by the vertical portion.

Regarding the area of the horizontal part, for example, even if an appropriate number of screw holes are drilled in the horizontal part and the horizontal part is formed to a width that can be screwed to the floor or a suitable support, the waveform of the discharge current will be affected. We were able to suppress the turbulence to an extremely high degree compared to conventional methods.

Figure 10 (horizontal axis is elapsed time t, vertical axis is current i)
A shows an ideal waveform of the discharge current, B shows an example of the waveform of the discharge current produced by the prototype electrostatic discharge simulator described in FIG. 3, and C shows an example of the waveform of the discharge current produced by the prototype electrostatic discharge simulator of the present invention. It is clear from the figure that the waveform C is much closer to the ideal waveform than the waveform B.

In addition, the ideal waveform in (a) is made closer to the waveform obtained by theoretical calculation by setting the length of the retrace line RGW to 10 cm to remove waveform disturbances due to the installation shape of the retrace line RGW, etc. Ha is return line RGW
This is the case when the length of is selected as 2m.

In each figure, the discharge starting voltage is 1kV, the capacitance of the charging/discharging capacitor is 120pF, and the discharge resistance is 250Ω.

[Brief explanation of the drawing]

1 and 2 are diagrams showing an embodiment of the present invention, FIGS. 3 to 7 are diagrams showing the configuration of a charging/discharging probe used in the present invention, and FIGS. 8 and 9 are diagrams showing an embodiment of the present invention.
The figure is an equivalent circuit diagram of an electrostatic discharge simulator, Fig. 10 is a waveform diagram of a discharge current, and Fig. 11 is a diagram showing a conventional electrostatic discharge simulator.PLN...
...Support plate, HOD...Support tube, FL, FL ₁ and FL ₂
...Tsubabe, BT...Boruto, NT...Natsuto,
PRB...Charge/discharge probe, CAS _C ...Housing, SED
...Discharge electrode, INS ₁ to INS ₃ ...Insulator, T _S ...
...charging power supply circuit connection terminal, CSW...support conductor,
R _D ...discharge resistance, C _CD1 , C _CD2 ,...charging/discharging capacitor, R _B ...buffer resistance, RGW...return wire,
EUT...Test object, T _G ...Ground terminal, TED ₁ and TED ₂ ...Cylindrical electrode, TED _E ...End wall, _H1 to
H ₃ ... Handle, HOD ₁ and HOD ₂ ... Opposing piece, LH
...Bolt insertion hole, HOL...Charge/discharge probe insertion hole, C _CDT ...Composite capacitance of charge/discharge capacitor, B...Human body, r...Human body resistance, C _STB and C _STP
... Stray capacitance, L ... Distributed inductance,
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...Discharge gap.

Claims (1)

[Claims for Utility Model Registration] (1) A series circuit of a charging/discharging capacitor and a discharging resistor with a grounding side electrode connected to the housing is housed in a casing made of a conductor, and the end of the series circuit on the discharging resistor side a charging power supply circuit connection terminal provided with a discharge electrode while maintaining insulation between the housing and the housing, and a charging power supply circuit connection terminal provided with a non-grounded electrode of the charging/discharging capacitor in the series circuit while maintaining insulation between the housing and the housing; and a charge/discharge probe which is connected to the housing and has one end of a return line connected to the housing, and a charge/discharge probe that is provided facing the test object and that allows the charge/discharge probe to slide approximately perpendicularly to the plate surface and in the axial direction. 1. An electrostatic discharge simulator comprising a supporting plate formed of a conductor and supporting the electrostatic discharge simulator. (2) The electrostatic discharge simulator according to claim 1, wherein the charging/discharging capacitor constituting the charging/discharging probe is a lumped constant capacitor. (3) The electrostatic discharge simulator according to claim 1, wherein the charging/discharging capacitor constituting the charging/discharging probe is a distributed constant capacitor. (4) The utility model claimed in claim 1, wherein the support plate has an L-shaped cross section, and a support tube for slidably supporting the charging/discharging probe is provided on the vertical portion of the support plate in a direction substantially perpendicular to the plate surface. Electrostatic discharge simulator. (5) A distributed constant type capacitor comprising a cylindrical casing made of a conductor and a cylindrical electrode provided inside the casing so as to face the casing with an insulator in between. electrostatic discharge simulator. (6) The electrostatic discharge simulator according to claim 4, wherein the support tube is fixed to the support plate. (7) The electrostatic discharge simulator according to claim 4, wherein the support cylinder is detachably attached to the support plate. (8) The electrostatic discharge simulator according to claim 4, wherein the support cylinder is composed of opposing pieces having an arcuate cross section and is attached to the support plate so that the opposing gap can be changed. (9) The electrostatic discharge simulator according to claim 7, wherein the support tubes having different inner diameters are selectively attached to the support plate.