JPS63143954A - Air ionizing method and device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relies on an air ionization device to generate electrostatically charged particles and ions in a clean atmosphere in which microelectronic devices can be manufactured. A “clean” room that creates
Air ionization reduces the possibility of unnecessary electrostatic discharge in "non-clean" rooms.

(Prior art) It is well known that air ionization, which creates an "ion chamber", is useful for providing a suitable dust-free environment for manufacturing semiconductor integrated circuits (C). Such ion chambers are typically equipped with a high-pressure neemitter that generates ions that expose the chamber to a charged environment that helps remove dust particles. Used in manufacturing integrated circuits It is known that removing dust from the chamber significantly improves the yield of the device, which becomes especially important as the characteristic size of the device becomes smaller and smaller.In addition, air ionization is unnecessary. This is an important technique for reducing the possibility of electrostatic discharge.

(Problems to be Solved by the Invention) High-pressure emitters used in conventional air ionization devices generate positive ions, generally continuously. the result,
Beyond the point where ionic charge accumulates inside the ion chamber, generating more ions is of no use. Conventional ion generators typically include high voltage electrical wires surrounded by a ground shield.

The ground shield has holes in multiple locations to allow the emitter point to be defined. Because these emitter points generate ions, they are kept at a relatively high voltage and can be potentially dangerous to the operator. Therefore, high voltage power lines are typically equipped with high impedance devices to limit the current flow and thereby reduce the hazard.

SUMMARY OF THE INVENTION The present invention provides that charged particles generated by an emitter inside an ion chamber diffuse through the ion chamber at a characteristic speed;
Also, an efficient mechanism for keeping the interior of the ion chamber dust-free is to pulse the entaster to generate both positive and negative ions, thereby keeping the chamber generally neutral. Based on the understanding of

The present invention includes a high pressure distribution device, such as a grid assembly, a plurality of emitter means connected to the distribution device for generating ions, and a plurality of emitter means connected to the distribution device such that the emitter means alternately generate positive and negative ions. The present invention relates to an air ionization device comprising: a voltage pulse generating means operable to generate a pulse voltage train containing at least one positive ion and at least one negative ion.

OPERATION In a first preferred embodiment, suitable for rooms with relatively weak airflow, the emitter means is held at 20 KV for a period of 0.1 to 0.2 seconds, and then for a period of approximately 0.3 seconds. 5K
V, and the latter voltage is used for repulsion but not for ion generation. Thereafter, the emitter means is turned on from 0.1 seconds to 0.
Negative to -20 KV for a period of 2 seconds, then to -5 KV for a period of approximately 0.3 seconds. A good flow chamber can use a second preferred embodiment, which is similar to the first preferred embodiment, but does not use ±5 KV pulses. Air flow helps disperse the ions. Reversing the polarity does not generate ions such that the ion distribution is uniform, thus providing an advantageously dust-free chamber with a relatively high yield annualized circuit. According to this,
The possibility of electrostatic charging is also reduced.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a schematic block diagram of a computer-controlled single point ion emitter discharge device 10. The device consists of an ion generation subsystem and a system controller.

The ion generation subsystem is PROTSUQUE GBl, ENGG8.
, . . . are represented by G to indicate N areas that operate independently.

The system controller is represented by block 12 and labeled mask controller in the figure. Mask controller 12 is connected by communication lines to slave controllers SC in each ion generation subsystem. This link is CLl, C
They are named L2, . . . cbM, and the slave controllers are named SG, SG, . . . SCN.

Each ion generation subsystem includes a high voltage bipolar amplifier that drives an emitter grid assembly mounted on the ceiling of the ion chamber. The amplifier is A1 in Figure 1.
, A2, . . . are represented by blocks named AN. The slave controller is typically 151...IFIN
It is connected to the input of the amplifier by the control line marked .

The output signal of the amplifier is connected to the slave controller by monitor lines 16□...16N. The amplifier inputs are signals generated by slave controllers SC1...EICN.

High voltage distribution devices, such as emitter grid assemblies, include high voltage electrical wires. The emitter pin extends from the high voltage line down into the room. In Fig. 1, the high-voltage line has M emitters for each subsystem with a short MI011, e
12,...81M Expressed as a line or 2.203,...
・Schematically expressed as 2nN. Emitters are subscripted, the first of which represents a subsystem;
The second one represents the emitter numbers from 1 to M. Therefore, the first and last emitters of the subsystem GS unit are named 01M. Similarly, the first emitter of subsystem G8N is named eMl and the last emitter 'NM.

High pressure i! #, generally designated as +, is connected to the output from amplifier A1, shown as a 20 KV amplifier in FIG. 1, for example.

A number of sensors I□...3ON are utilized to monitor the performance of the subsystem. Each sensor is labeled with a subscript that corresponds to the subsystem in which it is located. Therefore, the sensor in subsystem l8Gl is ()
It is named □. The sensor is the associated slave controller,
For example, it is connected to the input to the controller SC for subsystem IG8.

FIG. 2 shows a schematic diagram of a portion of an overhead emitter grid assembly. The high voltage wire (i.e., wire 1) of FIG. 1 is shown in FIG. 2 encased in an aluminum tube covered with a white epoxy coating.

The emitters are placed at predetermined locations along the wire to provide sufficient charge neutralization.

Each emitter has an emitter housing assembly, which is actually bound by a high impedance element consisting of a 00 megohm resistor.

FIG. 2 shows emitters e11 s e12, "13, each with a resistance of 100 megohms as shown.

Figure 2 also shows the wire section 1 connected to the amplifier Al by a 200 kilohm resistor 35, which is a relatively small resistor and is used to avoid ground wire noise. Ru.

FIG. 3A shows an emitter housing assembly 40 which has the important advantage of being easily attached to high voltages at any desired point. It is relatively quick and inexpensive to assemble, and the number of emitters can be increased as needed with virtually no effort. The emitter housing assembly is modular. Figure 3A shows wire 2
() It is an abbreviation of the cross-sectional view perpendicular to the axis of 1. The wire part is the third
In Figure A, the tube 31 is shown to be made of aluminum.

The emitter means or assembly 4 ( ) comprises a cylindrical sleeve 41 having a slotted tip 42 . Portion 42 is defined by solid axial opening 4 by barrier 44.
2 Separated from a. A pin hole penetrates through the barrier portion 44. The power supply is edge mounted in the slot 42 and a 100 megohm current limiting resistor 43 is disposed within the solid axial port 43. The resistor 43 is connected to the opening 42a
It has a pin-shaped tip that extends through the wire and contacts the wire pouch. The resistor 43 has a lipped lower end 45 into which an emitter, such as a tungsten needle 45a, is inserted.
Gin is inserted. Needle 45 a is solid shaft opening 4
The current limiting resistor is protected from direct contact by a retainer 46 which is press fit into the current limiting resistor 3 and holds the current limiting resistor in place.

FIG. 3B shows an enlarged view of the tungsten needle 45a. In general, the shape and material used for the emitter pin is important. In the prior art, the emitter f is made to have a very sharp point on the theory that ion generation is improved by a high electric field near a very small radius. While this is true, it is also true that high electric fields tend to emit particles from the tip. This is a particular problem when the tip is made of stainless steel, as in the prior art. Rather, the emitter pin of the present invention minimizes the radius of curvature of its tip, such as about 0.0002 inches, to minimize electric field strength, thereby reducing the potential for radiation of material from the tip. The use of hard materials such as tungsten as opposed to stainless steel also reduces material radiation. Tungsten needle 45a is circular in cross-section, with a maximum diameter of approximately 0.020 inch and an overall length of approximately 0.74 inch. The length of the cylindrical portion of the tungsten needle 45a is approximately 0.
700 inches, and the angle of the cone is approximately 1σ.

The radius of curvature of the tip is approximately 0.002 inches. 3rd A
As shown in the figure, the cable #I20 is held in place by a mating cap member 47 that is screwed into place as shown. The tube 31 is provided with an aperture at each possible emitter position, as shown in FIG. Emitter housing assembly 40 is press fit into tube 31 as shown in FIGS. 3 and 4. The cap 47 is press-fitted into a predetermined position through the openings, and screwed into the screw hole 49 with a bolt to a predetermined position ft.

FIG. 5 illustrates the modular portion of the grid assembly. FIG. 5 shows the length [11!20↓] surrounded by the tube 31. The wirework is completed with high voltage male and female connectors 51 and 52 as shown. The assembly is made to fit standard support brackets for typical clean room ceiling filters, similar to traditional acoustic drop ceiling supports. This instant device consists of an emitter grid as marked in Figure 6.
Assembly with ceiling support hanger. Each hanger ω is generally Y-shaped as shown and is adapted to attach to standard filter supports 61 and 62.

At the bottom of each hanger ω is a tube adapted to receive the tube 31 of the emitter assembly of FIG.

Master controller 12 of FIG. 1 controls the ion generation subsystem, monitors subsystem performance, and communicates with remote computers. For example, the mask controller is N8
It is a computer based on the C8QQ microprocessor (available from National Semiconductor) and its primary function is to integrate one or more slave controllers present in each device. The mask controller integrates all of the individual areas of FIG. 1 into one integrated device where all system information and parameters of the FIG. 1 installation can be entered and inspected through terminals 70. The mask controller continuously checks that each controller is operating correctly, thereby increasing the reliability of the entire system. The mask controller is designed to work under normal operating conditions and requires no operator intervention unless a problem occurs. Warning signals are usually generated before such problems occur so that action can be taken to avoid serious problems.

FIG. 7 is a block diagram of the mask controller. As shown, the controller includes an R8232 interface 101 and a power source 100. Power supply 100 is +5, +1
Terminal 70 and auto-dial modem 71 are shown connected via interface 101. The mask controller's N5C-8QQ central processing unit [ (CPU) is represented by block 103.

The CPU is driven by a real-time clock 105 and has a memory 10.
It is designed to communicate with 6. CPU is 40-20m
a current loop interface multiplexer 1
07 and communicates with the slave controller via this interface.

FIG. 8 is a block diagram of slave control @ (8C1). Each slave controller is also represented by block 110! Has pond backup power. The slave controller also communicates with multiplexer 107 of FIG.
It is equipped with a 20m long current loop Inc-7 Ace 112. The slave controller cpυ is represented by block 113 and operates in conjunction with memory 114. Slave controller is analog/digital converter/multiplexer 1
15 through which it receives amplifier voltage, amplifier current, and sensor power 0, 1.2.3.4, and 5. Multiplexer 115 is connected to an input to CPU 113. The output from the CPU is connected to a digital-to-analog converter 118 and a 120V AC relay 119 to provide a 20KV amplifier control input and a 20KV amplifier chamber @ (to 120V).

An auto-dial modem 71 (Figure 1) provides backup computer support in the event of an abnormal condition such as an amplifier exceeding its calibration value, drawing excessive current, or becoming out of control. It is connected to the controller 12 so that it can be changed. One area also includes an auto-dial modem (not shown) connected to the slave controller for similar operation in the unlikely event that controller 12 fails.

Each slave controller in Figure 1 (8G, SC,...
8CN), like controller 12, is a device based on the N8C3QQ microprocessor. Each initiates and monitors the operations of the area in which it resides. The slave controller's primary task is to control the input to the high voltage/1 Ivora amplifier and then monitor the voltage and current outputs of the amplifier as well as the outputs of up to six charge measurement sensors in the area. A continuous FEC system is provided for automatic calibration of ion generation to ensure that no net charge is introduced into the chamber. The slave controller also controls the AC'fl power input to the associated 20 KV amplifier and can remove it if the device's JIfr is indicated. Each region can operate independently of each other. For example, if bar Pware in one area breaks down,
Other areas continue to operate normally.

A slave controller (Figure 8) controls ion generation by the device by controlling the input to the high voltage amplifier. The waveform sent to the amplifier calculates the number of both positive and negative ions that occur during a given period of time. Q. If you change this waveform, the ion output will shift. The slave controller uses its foot nosec output to modify this waveform to provide sufficient and consistent charge neutralization as explained below. The controller makes appropriate changes to the waveform driving the amplifier for calibration and biasing purposes, but typically does not change the overall shape of the waveform. The waveform is determined by the characteristics of each device at and is programmed into the slave controller from the mask controller. The main considerations for this connection are the selection of the rate of charge decay and the maximum allowable voltage. The sensor used in this device is a capacitively coupled charge sensor, but the design is flexible to extend the system to incorporate other types of sensors such as ion counters and particle counters. Typically, 6 ion sensors are used in one area, but 81 (5
) is preferable.

Figure 9 has been found to optimize the performance of the device (
(idealized) waveform. As shown in Figure 9, the device maintains +20KV for 0.1 to 0.2 seconds.
It then drops to a level of +5KV for about 0.3 seconds. The device then similarly maintains -5KV. The duration of the voltage level is determined by a slave controller responsive to device sensors to maintain an optimal environment.

An important attribute of the overall system is the dual processor operation of the mask controller and slave controller. Locally, a particular region's slave controller has complete control of that region's amplifiers. The slave controller can be programmed to make shutdown decisions based on its monitor inputs in the event of hardware failure or other abnormal conditions.

In addition to the importance of continuous charge neutralization, due to the high voltages involved in the equipment, it is important to use a second processor (mask controller) to check that the slave controllers are operating properly. There is. This dual processor operation not only improves the fault detection capability of the overall system, but also significantly reduces the potential for hazards.

Additionally, a high voltage bipolar amplifier of V is part of the pulse generation means for generating the high voltage signal used to generate the ion radiation. Amplifier input 1d from -10V to +IOV
It takes in the signal and amplifies it approximately 2000 times to generate an output signal. This signal becomes the output voltage monitor and output current monitor that the slave controller uses as part of the digital fee pack system. This amplifier is 20KV
can drive a current of 3ma. There is one amplifier per region.

The valley subsystem consists of 35KV insulated high-voltage wires and 4 white wires.
-w A resin-coated aluminum tube and an emitter assembly. 35'V wires are used to distribute high voltage signals throughout the grid assembly. The purpose of aluminum tubes is twofold. One is to serve as a structural support for high-voltage electric wires, and one is to provide high-voltage TI1. The wire acts as a grounding shield that terminates the radiated electrostatic field. Such electric fields can induce static charges that cause transients in devices, equipment, and instrumentation. Emitters are placed every 18 inches and provide a source of ion radiation.

The emitter grid assembly is constructed to avoid ion attraction and reduce maintenance. For example, tube 31 may be coated with a non-conductive material to avoid attracting ions. Additionally, high voltage transmission wires are used with carbon-doped plumes that fill the normally open spaces within the wires. Eliminating the air space eliminates the hissing noise that typically occurs in high voltage environments and requires less maintenance.

The optimal state is the sensor 30 in FIG. ,30g,...
This is obtained when the voltage (V) waveform exhibits +1J1(t) characteristics characterized by a negative second derivative for both positive and negative pulses for 30 seconds. When this condition is met, the ions in the chamber are in equilibrium. If this condition is not met, the second derivative of the voltage with respect to time is used to generate positive and negative ions. It can be made negative by adjusting the width of Q Lus.

In addition, another important way to monitor performance is to minimize the mean square or absolute value of the sensor voltage. Typically, prior art devices monitor the average sensor voltage, which varies between +IOV and -10V and +1500V.
Voltage oscillations between V and -1500V cannot be distinguished, even though the ion production of the two oscillations is completely different.

FIG. 10 shows the first
The voltage of the example sensor 301 shown in the figure is plotted against time. FIGS. 11 and 12 show the first derivative of voltage with respect to time and the second derivative of voltage with respect to time taken in the double arrow 2000 area of FIG. 10. FIG. The derivative is taken, for example, over the last nine coefficients of the curve.

The waveforms of FIGS. 11 and 12 are generated by slave controller SC1 according to algorithms well known in the art.

Another technique for determining whether the positive and negative ion equilibrium conditions are met is to measure the charge that develops on the test plate in response to each pulse in FIG. The charge is do IJ
7) It is put into a coulometer that senses K. Drift is a sign of imbalance and can be corrected by changing the KA pulse width as described above.

The overall concept of using a mask slave system in combination with the present invention results in a highly practical and easily expandable device. This is particularly attractive since only one mask is required for multiple separate slave devices at remote locations. Each slave device operates independently of other slave devices. The interaction between the mask device and the slave device may be used to extend the control and monitoring of the slave device to substantially improve the reliability and operation of the air ionization device. The mask device generates good news when the operation of the device changes and can distinguish between a warning and a stop. It also operates a computer. 6 Alerts are sent to the local user via the local terminal and modem to the important device/Q.
This is a warning that the parameter has changed beyond a preset darkness value. The warning device is set to allow the air ionizer to balance and effectively dissipate excess static charge so that the device can continue to operate. Therefore, a warning indicates that a problem may exist, and if such a condition or situation continues to worsen, the high voltage may cease, and thus ionization may cease.

As such, a warning is an advanced indicator of the possible existence of a problem before a shutdown is necessary. This allows for early preventive maintenance and possibly planned outages before an emergency occurs and an outage is expected. Such actions, all warnings and outages are recorded in the state history. Typically, the monitored parameters are voltage calibration, maximum ionization current, minimum ionization current, sensor offset, and senna peak-to-peak voltage.

The device samples the power supply to the device and checks for any abnormalities. To account for voltage fluctuations or temporary interruptions, the device is designed with a 5 minute interruption before using battery backup. This delay takes into account the time it takes for the backup generator to enter the line. To avoid damage to the device, a delay is introduced before it goes from the battery to the power line. A delay of 5 minutes will be adopted.

The particular waveform used to achieve optimal ionization can take many different forms. For example, the waveform can include maximum applied pulses of different magnitudes and durations. Waveform transparency may vary depending on various factors such as compromising peak-to-edge voltage versus decay time or accommodating forced air and non-forced air systems. Of course, pulses of one polarity are followed by the opposite polarity according to the invention. The e-cis group follows. The two groups need not be identical.

Over long periods of time, air ionizer operation tends to induce electrical potentials on the work surface and all components of the blank. This is an undesirable aspect of air ionization;
Instant devices tend to minimize voltages induced within the room. Nevertheless, other embodiments of the invention, as shown in FIG. 13, are even more effective at minimizing work surface and component pressure induced potentials.

FIG. 13 shows the power supply 13 in response to a mask controller (not shown).
A slave controller 130 is shown controlling 2 and 134. Power supplies 132 and 134 generate voltage pulses of opposite polarity according to the present invention. High pressure'[#136
and 138 are located in alternating columns of the ceiling grid and out of phase with respect to each alternating column so that adjacent alternating columns generate positive ions while adjacent alternating columns generate negative ions. has been done. Some of the field lines emanating from the M-charged ions end in oppositely charged ions rather than at the workpiece surface, which reduces the potentials induced on the workpiece surface and components within the chamber.

FIG. 14 is a partial table of an improved sensor suitable for measuring real-time potential decay. The improved ion senna shown in FIG. 14 typically uses conventional plate separation solenoids 144 with voltages of ±5000 volts to isolate the senna plate 1.
42 is provided with a high voltage power source 140 that charges the battery. Isolation solenoid 144 allows high voltage power supply 140 to contact floating plate 142 during charging periods and to isolate floating plate 142 during decay periods. Importantly, the isolation provided by the isolation solenoid 144 is so strong that leakage through the solenoid 144 causes little or no charge decay. The rate at which the charge on floating plate 142 decays is a measure of the density of ions present in the chamber. A positive initial voltage is used to measure negative ions, and a negative initial voltage is used to measure positive ions. The results of the attenuation measurements are entered in a diary and can optionally be used to balance the device.

FIG. 15 shows an improved emitter connection to the high voltage 'tIL line. A high voltage wire 150 is centered on an aluminum CRF 152 with an insulator 154. The end of the high voltage wire 150 is connected to an extension 156 that includes a locking tab 160. A high voltage electric wire 162 is installed within an aluminum tube 164 with an insulator 166. Aluminum tube 164 has an interior that receives extension 156 and a socket (168) that engages bin 160.
It is equipped with Aluminum tube 1 with metal spring washer
The grounding between 52 and 164 is not interrupted.

Although the invention has been described herein with reference to specific embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the invention. It is therefore to be understood that aesthetic modifications may be made to the illustrative embodiments and designs thereof may be devised without departing from the spirit and scope of the invention.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an ion neutralization device according to the invention; FIG. 2 is a schematic diagram of a portion of the emitter grid assembly of the device of FIG. 1; and FIG. 3A is an ion emitter housing according to the invention. - Schematic broken sectional view of assembly, 3rd
Figure B shows the ion emitter housing shown in Figure 3A.
4.5 and 6 are schematic illustrations of portions of the grid assembly of FIG. 2; FIGS. 7 and 8 are schematic views of portions of the grid assembly of FIG. 1 is a block diagram of the mask controller and slave controller of the device of FIG. 1; FIG. 9 is a diagrammatic representation of the emitter waveform of the device of FIG. 1; FIG. FIG. 13 is a block diagram of another embodiment of the present invention, and FIG. 14 is a diagram showing the measurement of real-time potential decay. Figure 8g15 is a partially sectional side elevational view of the connection of the improved emitter to the high voltage line. 31... Tube, 40... Emitter housing assembly, 41... Cylindrical sleeve, 43... Current limiting resistor, 45 fL... Tangesty needle, 51, 52
...Connector, ell + 012 + '13°0
Emitter. Patent applicant Voyager, Technologies F/N, JA F/N, 5 FIG, 6 FIG,
9FIG, 7 F-3・2 313 F, U, Ri, Agricultural Procedures Amendment 1986-51, 1988 Patent Application No. 288635 2, Title of Invention Air Ionization Method and Apparatus

Claims (1)

[Claims] 1) Ionization of air, characterized in that the method comprises: 1) providing a plurality of emitter means and applying a pulse voltage train to the emitter means so that the emitter means alternately generate positive and negative ions; how to. 2) further providing a second plurality of emitter means and applying a second pulse voltage train to the second plurality of emitter means, whereby the second plurality of emitter means alternately emits positive and negative ions; The first claim that includes
The method described in section. 3) The method of claim 1, wherein the pulse voltage trains are of equal magnitude and opposite polarity. 4) Additionally, operate the air ionization device from the power line, monitor the power line to ensure that there is insufficient voltage to operate the device, maintain battery backup for the device, and ensure that the power line is 2. A method as claimed in claim 1, including switching to backup by said battery as a power source for said device after stopping the supply of sufficient voltage for a predetermined period of time. 5) a high voltage distribution device, a plurality of emitter means connected to the distribution device, and connected to the distribution means for generating a pulsed voltage train comprising at least one positive pulse and at least one negative pulse; 1. An air ionization device comprising: pulse generation means which operates to cause the emitter means to alternately generate positive and negative ions. 6) The apparatus of claim 5, wherein said emitter means comprises a high impedance connected to a wire grid assembly. 7) The device of claim 6, wherein the high impedance comprises a resistor. 8) Further, sensor means operable to detect the presence of positive ions and negative ions, and a sensor means connected to the sensor means and the pulse generating means, the sensor means operable to detect the presence of positive and negative ions; 6. The apparatus of claim 5, further comprising control means operative to control the pulse generating means. 9) The sensor means is operative to generate an output voltage representative of ions, and the control means is operative to generate a signal proportional to the square of the respective voltage from the sensor means. Apparatus according to scope 8. 10) the control means is operative to calculate the second derivative with respect to time of a predetermined portion of the signal from the sensor means and adjust the pulse generating means such that the second derivative is always negative; 9. The apparatus according to claim 8. 11) further comprising a second high pressure distribution device, a second plurality of emitter means connected to said second distribution device, and at least one positive pulse and at least one positive pulse connected to said second distribution means; and a second pulse generating means that operates to generate one negative pulse, whereby the second emitter means alternately generates positive and negative ions. Equipment described in Section. 12) Device according to claim 11, characterized in that the distribution devices are arranged alternating with each other. 13) The apparatus of claim 12, wherein the pulse trains are of equal magnitude and opposite polarity. 14) the pulse voltage train is composed of two groups of pulses;
Each group includes a first pulse for generating ions by the emitter means followed by a second pulse of the same number as the first pulse but different in magnitude, the second pulse causing the emitter means to generate ions. 6. The apparatus of claim 5, wherein substantially fewer ions are generated in such a way as to repel the ions generated from the first pulse. 15) The device of claim 5, wherein the high-speed distribution device comprises a high-voltage wire, and the emitter means has a modular configuration for connection to the wire. 16) The emitter means comprises a cap, a hollow cylindrical sleeve, means for mechanically engaging the cap and the sleeve, and a resistor inside the cylindrical sleeve and disposed between the cap and the sleeve. an emitter pin connected to the resistor and arranged to be connected to the wire when the resistor is engaged. Device. 17) The apparatus of claim 5, wherein said emitter means comprises an emitter pin made of tungsten and having a dotted tip with a radius of approximately 0.002 inches.