Powerex, Europe, S.A. Avenue G. Durand, BP, Le Mans, France ( 43) Phase Control SCR. Amperes ( RMS). Volts. This edition of the Thyristor Data Manual has been revised extensively to reflect our . For the first time in the Thyristor data book we included the UL safety. SYM. CO DI. G. |INCHES || | I I | MM. 1 T T1.
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We sincerely hope you will find this Power Semiconductor Data Book for Design .. The thyristor terms and definitions presented in this data book were obtained . Page 1. Page 2. Page 3. Page 4. Page 5. Page 6. Powerex, Europe, S.A. Avenue G. Durand, BP, Le Mans, France ( 43) Phase Control SCR. Amperes Average. Volts.
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A variant called an SCS—silicon controlled switch—brings all four layers out to terminals. The operation of a thyristor can be understood in terms of a pair of tightly coupled bipolar junction transistors , arranged to cause a self-latching action: Structure on the physical and electronic level, and the thyristor symbol. Thyristors have three states: Reverse blocking mode — Voltage is applied in the direction that would be blocked by a diode Forward blocking mode — Voltage is applied in the direction that would cause a diode to conduct, but the thyristor has not been triggered into conduction Forward conducting mode — The thyristor has been triggered into conduction and will remain conducting until the forward current drops below a threshold value known as the "holding current" Function of the gate terminal[ edit ] The thyristor has three p-n junctions serially named J1, J2, J3 from the anode.
Layer diagram of thyristor. When the anode is at a positive potential VAK with respect to the cathode with no voltage applied at the gate, junctions J1 and J3 are forward biased, while junction J2 is reverse biased. As J2 is reverse biased, no conduction takes place Off state. Now if VAK is increased beyond the breakdown voltage VBO of the thyristor, avalanche breakdown of J2 takes place and the thyristor starts conducting On state.
If a positive potential VG is applied at the gate terminal with respect to the cathode, the breakdown of the junction J2 occurs at a lower value of VAK. By selecting an appropriate value of VG, the thyristor can be switched into the on state quickly. Gate trigger current varies inversely with gate pulse width in such a way that it is evident that there is a minimum gate charge required to trigger the thyristor.
Switching characteristics[ edit ] V — I characteristics. In a conventional thyristor, once it has been switched on by the gate terminal, the device remains latched in the on-state i. As long as the anode remains positively biased, it cannot be switched off until the anode current falls below the holding current IH. In normal working condition the latching current is always greater than holding current.
A thyristor can be switched off if the external circuit causes the anode to become negatively biased a method known as natural, or line, commutation. In some applications this is done by switching a second thyristor to discharge a capacitor into the cathode of the first thyristor. This method is called forced commutation.
After the current in a thyristor has extinguished, a finite time delay must elapse before the anode can again be positively biased and retain the thyristor in the off-state.
This minimum delay is called the circuit commutated turn off time tQ. Attempting to positively bias the anode within this time causes the thyristor to be self-triggered by the remaining charge carriers holes and electrons that have not yet recombined. For applications with frequencies higher than the domestic AC mains supply e. Such fast thyristors can be made by diffusing heavy metal ions such as gold or platinum which act as charge combination centers into the silicon.
Today, fast thyristors are more usually made by electron or proton irradiation of the silicon, or by ion implantation. Irradiation is more versatile than heavy metal doping because it permits the dosage to be adjusted in fine steps, even at quite a late stage in the processing of the silicon. A bank of six A thyristors white disks arranged in a row at top, and seen edge-on Etymology[ edit ] An earlier gas-filled tube device called a thyratron provided a similar electronic switching capability, where a small control voltage could switch a large current.
It is from a combination of "thyratron" and " transistor " that the term "thyristor" is derived. Red trace: load output voltage Blue trace: trigger voltage. Thyristors are mainly used where high currents and voltages are involved, and are often used to control alternating currents , where the change of polarity of the current causes the device to switch off automatically, referred to as " zero cross " operation.
The device can be said to operate synchronously; being that, once the device is triggered, it conducts current in phase with the voltage applied over its cathode to anode junction with no further gate modulation being required, i. This is not to be confused with asymmetrical operation, as the output is unidirectional, flowing only from cathode to anode, and so is asymmetrical in nature.
Thyristors can be used as the control elements for phase angle triggered controllers, also known as phase fired controllers. For other conditions, see Fig.
For more than one cycle of applied voltage. Rate of Change of Forward Current, di 'dth. See waveshape of Fig. In the United Kingdom. Middle East, and Afnca, mountinghardware policies may differ; check the availability of all items shown with your ReA sales representative or supplier.
For ont' 'yc-lt, of lIpp! For mort. Symmetrical gate-cathode construction-provides uniform current density. PEAK Rr: PEAK f'! At oilIer case temperatures.
Gate Controlled TurnOn Trme: JunctlOntolsolated Stud. Mounting of press- fit package types depends upon an interference fit between the thyristor case and the heat sink. As the thyri stor is forced into the heatsink hole, metal from the heat sink flows into the knurl voids of the thyristor case. The resulting close contact between the heat sink and the thyri stor case assures low thermal and electrical resistances. If these dimensions are maintained, a "worst-case" condition of 0.
A slight chamfer in the heat-sink hole will help center and guide the press-fit package properly into the heat sink. These dimensions provide sufficient clearance for the leads and assure that no direct force is applied to the glass seal of the thyristor. The press-fit package is not restricted to a single mounting arrangement; direct soldering and the use of epoxy adhesives have been successfully employed. A f solder should be used and heat should be applied only long enough to allow the sold,'r to now freely.
Dimensions in parentheses are in millimeters and are derived from the basic inch dimensions as indicated. In the United Kingdom, Europe, Middle East, and Africa, mountinghardware polIcies may differ; check the availability of all items shown with your ReA sates representative or supplier.
Heatmg time should be sufficient to cause solder to flow freely. Mounted on heat sink with a mica 0. MAX, 12,8 13,81 14,28 5. Do not crush, grind, or portions.
Low thermal resistance Shorted-emitter gate-cathode construction T C for isolated-stud package types. Circuit Commutated. Thermal Resistance, Junetion-to-Case: Iffi ,: The resulting close contact between the heat sink and the. These dimen sions provide sufficient clearance for the leads and assure. The press-fit case is tinplated to facilitate direct soldering to the heat sink. The press-fit package is not restricted to a single mounting arrangement; direct soldering and the use of epoxy adhesives.
In the United Kingdom, Europe. Middle East, and Africa, mountinghardware policies may differ; check the availability of all items shown with your ReA satesrepresentative or supplier. Countour and angular orientation of these terminals is optional. Outer diameter of knurled surface. ASA Recommended torque: W is pitch diameter of coated threads. ASA 8,. Isolating material ceramic between hex stud and terminal.
The ceramic of the isolatedstud package contains beryllium oxide. Do not crush, grind, or abrade this part because the dust resulting from such action may be hazardous if inhaled. Disposal should be by burial. Symmetrical gate-cathode construction - provides uniform current density, rapid electrical conduction, and efficient heat dissipation.
All-diffused construction - assures exceptional un iformi ty and stabi Iity af characteristiCs. Exceptionally high stud-torquecapabil ity through use of high-strength copper-alloy stud. For other case temperatures and conduction angles. Peak Surge Current, iFM surge f: For one cycle of applied voltage.
Complete threads threads of head. Angular orien'tation of these terminals IS unSquare or radius on end of terminal is optional.
Screw Thread Standards for. Dynamic Dissipation: Forward Breakover Voltage. DC Gate-Trigger Current. DC Gate-Trigger Voltage. Holding Current. IGT mA. Middle East, and Africa. HoTE I: HoTE 2: HoTE 3: Soldering 10 s max.
For example: This required case-ta-air thermal resistance included both case-ta-heat sink and heat sink-toair thermal resistances. Typical values of case-ta-heat sink thermal resistances for different mounting arrangements are shown in Table l. Thermal resistance characteristics of commercial heat sinks are contained in various manufacturers' data sheets. Dow Corning silicone heat-sink compound, or equivalent.
Dimensions in parentheses rived from the basic inch dimensions NOTE 2: The recommended. The applied during installation should not exceed 50 in. These RCA types are all-diffused, silicon controlled rectifiers designed for high-frequency power-switching applications such as inverters, switching regulators, and high-current pulse.
Shorted-emitter gate-cathode construction Peak Forward for 10 IJs max. Typical variation of turn-off time with rate-of-rise of reapplied off-state voltage rectangular pulse ,. Jlocking circuits, power supplies, and other military md industrial applications.
These devices have dc forward-current ratings to 0. The INB through INB feature 1 sturdy and compact mount structure, 2 axial leads for flexibility of circuit connections, 3 welded hermetic sealsevery unit is pressure-tested to assure protection against moisture and contamination, 4 superior junction formation made possible by a diffusion process with very precise controls.. In addition, these devices are designed to meet the following stringent environmental, mechanical and life requirements of prime importance in military applications: Maximum Reverse Current averaged over I complete cycle of supply voltage: The maximum ratings in the tabulated data are established in accordance with the following definition of the Absolute-Maximum Rating System for.
The device manufacturer chooses these values to provide acceptable serviceability of the device, taking no responsibility for equipment variations, environment variations, and the effects of changes in operating conditions due to'vdriations in device characteristics. The equipment manufacturer should design so that initially and throughout life no absolutemaximum value for the intended service is exceeded with any device under the worst probable operating conditions with respect to supply-voltage variation, equipment component variation, equipment control adjustment, load variation, signal variation, environmental conditions, and variations in device characteristics.
The flexible leads of these rectifiers are usually soldered to the circuit elements. It is desirable in all soldering operations to provide Some slack or an expansion elbow in the leads to prevent excessive tension on the leads.
It is important during the soldering operation to avoid excessive heat in order to prevent possible damage to the rectifiers. To absorb some of the heat, grip the flexible lead of the rectifier between the case and the soldering point with a paIr of pliers.
Furthermore, the leads should not be dip soldered beyond points A and B indicated on the Dimensional Outline Drawing. It is recommended that these rectifiers be mounted on the underside of the chassis. Within the 0. Stringent environmental and mechanical tests to insure dependable performance in industrial and military applications. Peak reverse voltages from SO to V. These silicon rectifiers have peak reverse voltage ratings from SO to volts, and a maximum reverse current of S. These silicon rectifiers are designed to meet such stringent environmental, mechanical, and life requirements of prime importance in military applications as: Averaged over 1 complete cycle of supply voltage: RCA-1NA and lNA are hermetically sealed silicon rectifiers of the diffused-junction type, designed for use in power supplies of color and black-and-white television receivers, radio recei vers, phonographs, high-fidelity amplifier systems, and other electronic equipment for commercial and industrial applications.
The new rectifiers Incorporate all of the superior performance and reliability features which have gained industry acceptance for thei r RCA prototypes, and, in addition, offer substantially higher dc-outputcurrent capabilities, lower reverse leakage currents, lower forward voltage drop, and a wider operating-temperature range.
Both devices have dc forward-current ratings of 1 ampere - resistive or inductive load, and 0. They can provide dc output currents of up to 2 amperes to capaci tive loads when attached to simple heat sinks. RCA-1NA has a peak-reverse-voltage rating of volts, and is intended for applications in which the rectifier operates directly from an ac power line supplying up to volts rms for capacitive loads, or up to volts rms for resistive or inductive loads. RCA-1NA has a peak-reverse-voltage rating of volts, and is intended for applications in which the rectifier operates from an ac line through a step-up transformer supplying up to volts rms for capacitive loads, orup to volts rms for resistive or inductive loads.
They utilize the JEDEC flanged-case, axial-lead package which provides flexibility of installation in both hand-wired and printed-circuit equipment designs. These new rectifiers, like their RCA prototypes, are conservatively rated and incorporate the following design features: For operation with resistive inductive loads For operation with capacitive.
At half-load current of ma. At full-load current Approx. Voltage Regulation to full-load current. Fi Iter-Input Surge-Limiting. At full-load current of ma. Voltage Regulation Approx. Half-load current to full-load current.
At half -load current of ma. At fu II-load current of ma. Dimension to allow for pinch or seal deformation anywhere along tubulation optional. Diameter to be controlled from free end of lead to within 0.
The new rectifiers incorporate all of the superior performance and reliability features which have gained industry acceptance for their RCA prototypes, and, in addition, offer substantially higher dc output-current capabilities, lower reverse leakage currents, and a wider operating-temperature range. All seven of these new rectifier types have maximum dc-forward-current ratings of 1 ampere for resistive or inductive 10ads and 0. They are also capable of providing dc output currents of up to 2 amperes with capacitive loads when attached to simple heat sinks.
These new rectifiers, like their RCA prototypes, are conservatively rated, and incorporate the following design features and special tests which contribute to their outstanding performance and reliability: For ambient temperatures up to 75C.
For ambient temperatures above 75C, see Rating Chart. Characteri stic s: Maximum Reverse Current: RCA-l N N, inclusive, are diffused-junction type silicon rectifiers in an axial-lead plastic package. These devices differ only in their voltage ratings. Their small size and plastic package of high insulation resis tance make these rectifiers especially suitable for those applications in which high packaging densities are employed.
For one-half cycle of applied voltage,. For single-phase, half-wave sinusoidal pulse of duration with a repetition rate of 60 pulses per second.
For single-phase, half-wave operation with a GO-Hz sinusoidal supply and a resistive load. Reverse-Recovery Time: Heat-sink mounting with o-to-1 Y-," leads, and with a pulse duration of 0. For other pulse durations, see Fig. Single-phase, half-wave operation with Hz sinusoidal voltage and resistive load; with '" leads. Instantaneous Forward-Voltage Drop: Steady-State J-HS t. Heat-sink mounting with 1-inch leads. For other mounting methods and other lead lengths, see Fig.
Heat-sink mounting with 0 to 1" leads, and with a pulse duration of 0. These silicon rectifiers are intended for use in generator-type power supplies for mobile equipment; in dc-to-dc converters, power supplies for de motors, transmitters, rf generators, welding equipment, and electroplating systems; in dc-blocking service, magnetic amplifiers, and in a wide variety of other applications in industrial equipment.
High output current: In the United Kingdom, Europe, Middle East, and Africa, mountinghardware policies may differ; check the availability of all items shown with your ReA sates representative or supplier. Used in generator-type power supplies for mobile equipment; in dc-to-dc converters, battery chargers, and machine-tool controls; in power missile.
At Cease temperature. At other case temperatures.
Fig,6 - Typical Forward Characteristics all Types and corresponding reversepolarity versions. Because these rectifiers may operate at voltages which are dangerous, care should be taken in the design of equipment to prevent the operator from coming in contact with the rectifier.
The applied torque during installation not exceed 25 inch-pounds. The procedure for the use of Fig. From Fig. For dc operation use current multiplYing factor of 0. Step 2: Divide the required load current in amperes by the number of rectifier circuit branches - as shown in the following Table to determine average forward amperes per rectifier cell.
Center-Tapped Bridge Three -Phase: Step 3: Multiply average forward amperes established in Step 2 by the current-multiplying factor established in Step 1 to determine adjusted average forward amperes per rectifier cell, for use with Fig.
Using the product obtained in Step 3. Polari ty symbol for types lNlRA. Determine mlnlmum heat-sink Slze. Step 1: For three-phase half-wave operation the number of rectifier circuit branches is three. Multiplying average forward amperes 10 obtained in Step 2 by the currentmultiplying factor 1. Step 4: Hote I: The appl ied torque duri. Hote 3: Angular orientation of this terminal is undefined. Thedevice maybeoperated inany position. Appl icat ions: Superimposed on device operating within the maximum specified voltage, current, and temperature ratings and may be repeated after sufficient time has elapsed for the device to.
Fif 1 - Rattnf Chart 1NC. Because these recti fiers may operate at vol tages which are dangerous, care should be taken in the design of equipment to prevent the operator from coming in contact wi th the recti fier.
The appl ied torque during installation should not exceed 75 inch-pounds. The procedure for the use of O1art V is as follows: Step I: From Chart V determine the currentmultiplying factor for the applicable conduction angle. For dc operation use current multiplying factor of 0.
Type of Operation No. Center-Tapped 2 Sri e 2 ree-. Multiply average forward amperes established in Step 2 by the current multiplying factor establ ished in Step 1 to determine ad-. Using the product obtained in Step 3, determine from Rating Chart II or Rating O1art III either a the maximum allowable incomingair temperature or ambient temperature for a given heat-sink size, or b the minimum heatsink size for a given incoming-air temperature or ambient temperature.
Cond itions: From O1art V, the current multiplying factor for a conduction angle of is 1. Multiplying average forward amperes 05 obtained in Step 2 by the current multipI ying factor 1. From Rating Chart III, for forcedair cooling, the minimum heat-sink size for the conditions shown in Step 3 is 3" x 3".
They are also extremely useful in power supplies for de motors, in welding and electroplating equipment. At 1 SOOC case temperature At other case temperatures Operating and storage Forward Voltage Drop Volts b Reverse Current mAl:. These rectifiers are conservatively rated to permit continuous operation at maximum ratings in applications requiring high reliability under severe operating conditions.
In addition, they utilize a special zirconium-alloy mounting stud which can withstand installation torques of up to 50 inch-pounds a feature of significant value in applications involving mechanical shock and vibration.
Ch"mfer Ofundercut on one or both of hex. Recommended torqu.: Cylindrical design with axial leads for simple handling and installation Compact, hermetically sealed metal case 0. Insulated types 1N, 1N, 1N, 1N, and 1N have transparent, high-dielectric-strength plastic sleeve over metal case. RCA-1N, lN, lN, lN, lN, lN, 1N, 1N, and 1N are hermetically sealed silicon rectifiers of the diffused-junction type utilizing small cylindrical metal cases and axial leads.
Type lN is an insulated rectifier which does not have an uninsulated equivalent. Designed to meet stringent temperature-cycling and humidity requirements of critical industrial and consumer-product applications. For free-air temperatures. Voltage Drop at dc forward current of 0. Typical operation characteristics of types in fullwave voltagedoubler service. Dielectric Strength: Degree of Transparency:. Operation from supply voltages between and V nominal. Ability to handle high beam current; average 1.
Ability to supply as much as 7 mJ of stored energy to the deflection yoke, which is sufficient for 29 mm-neck picture tubes, as well as These ReA types are designed for use in a horizontal output circuit such as that shown in Fig. To initiate trace-retrace switching and control yoke current during retrace.
To facilitate direct connection across each silicon controlled rectifier, SSF and SSF, the anode connections of silicon rectifiers DS and DSF are reversed as compared to that of a normal power-supply rectifier diode. Gate Power Dissipatione; Peak forward or reversel. T C BOoC Peak Forward Off-State Current: Up to V max. This parameter, the sum of reverse recovery time and gate recovery time, is measured from the zero crossing of current to the stan of the reapplied voltage. Knowledge of the current, the reapplied voltage, and the case temperature is necessary when measuring tq.
Nonrepetitive peak Repetitive peak Peak-surge nonrepetitive Operating ICase. For ambient temperatures up to 45C. Maximum current rating applies only if the rectifier is properly mounted to maintain junction temperature below C.
The SCR's and rectifiers can be operated at full current only if they have adequate heat sinking. A single aluminum plate made as shown in Fig. These RCA devices are silicon controlled rectifiers and silicon rectifiers intended for use in horizontal-deflection circuits of large-screen color television receivers.
A simplified schematic diagram for the utilization of these SCA's and silicon rectifiers is shown below. For detailed information on the operation of this new deflection circuit, seeApplication.
Breakover Voltoge: With gate open. Instantaneous On-State Voltage: For an on-state current of 30 A. Peak Surgee Ambient Temperature Operating.. Fast reverse-recovery time trr 0.
These devices feature fast recovery times 0. Reverse Recovery Time: For circuit shown in Fig. Thermal Resistance Junctionto-Case For one-half cycle of applied voltage, 60 Hz 8. ReA D series and DR series are junction silicon rectifiers in a stud-type hermetic These devices differ only in their voltage. For one-half cycle of applied voltage, 60 For other durations Peak repetitive. Maximum allowable case temperature as a function of peak current and duty factor for units with maximum forward voltage drop.
Chamfer or unde,eul on one Or both "des 01 huaganal base " optional 2: Angular orientation and contour of Terminal NO. Handbook H 28 Part 1 RKommended torque: Europe, Middle East, and Africa, mountingdiffer; check the availability of all items or supplier.
Available in reversepolarity versions: All types feature fast reverserecovery time of ns max. These devices are intended for use in high-speed inverters,. Handbook H 28 P. At j'. For one-half cycle of applied voltage, 60 Hz Available in reverse-polarity versions: All types feature fast reverse-recovery time of ns max. These devices are intended for use in high-speed inverters. For one cycle of applied voltage, 60 Hz For ten cycles of applied voltage.
In the United Kingdom, Europe, MIddle East, and Africa, mountinghardware policies may differ; check the availability of all items shown with your ReA sales representative or supplier. Recommended tOf"que: Low reverse-recovery current Low forward-voltage drop Low-thermal-resistance.
These devices are intended for use in high-speed inverters, choppers, high-frequency rectifiers, "free-wheel ing" diode circuits,. In the United Kingdom, Europe, Middle East, and Africa, mountinghardware policies may differ; check the availability of all Items shown with your ReA sales representative or supplier.
Chamfer or undercut on one or both Sides of hexagonal base is optional 2: Angular orientation. ScrewThread Standards for Federal Services. Handbook H 28 Part I Recommended torque: These devices are intended for use in high-speed inverters, choppers. Peak-surge non-repetitive: For one cycle of applied voltage, 60 Hz For ten cycles of applied voltage, 60 Hz Peak repetitive In the United Kingdom, Europe,.
W IS pilCh diameter of coed threads. These devices are intended for use in highspeed inverters, choppers, high-frequency rectifiers, "free-wheeling" diode circuits, and other high-frequency applications. Low reverse-recovery current Low forward-voltage drop Low-thermal-resistance hermetic package. Maximum pitc'" diameler of plaled t"'readss"'al!
For critical triggering applications requiring narrow breakover voltage range V -DY Typical breakover voltage: Both units exhibit teristics. Their small size and plastic package of high insulation resistance make these diacs especially suitable for. Solid state devices are being designed into an increasing variety of electronic equipment because of their high standards of reliability and performance.
However, it is essential that equipment designers be mindful of good engineering practices in the use of these devices to achieve the desired performance. This Note summarizes important operating recommendations and precautions which should be followed in the interest of maintaining the high standards of performance of solid state devices.
Absolute-Maximum Ratings are limiting values of operating and environmental conditions applicable to any electron device of a specified type as defined by its published data, and should not be exceeded under the worst probable conditions. The device manufacturer chooses these values to prOVide acceptable serviceability of the device, taking no responsibility for equipment variations, environmental variations, and the effects of changes in operating conditions due to variations in device characteristics.
The equipment manufacturer should design so that initially and throughout life no absolute-maximum value for the intended service is exceeded with any device under the worst probable operating conditions with respect to supplyvoltage variation, equipment component variation, equipment control adjustment, load variation, signal variation, environmental conditions, and variations in device characteristics.
It is recommended that equipment manufacturers consult RCA whenever device applications involve unusual electrical, mechanical or environmental operating conditions. The design flexibility provided by these devices makes possible their use in a broad range of applications and under.
When incorporating these devices in equipment, therefore, designers should anticipate the rare possibility of device failure and make certain that no safety hazard would result from such an occurrence. The small size of most solid state products provides obvious advantages to the designers of electronic equipment.
However, it should be recognized that these compact devices usually provide only relatively small insulation area between adjacent leads and the metal envelope. When these devices are used in moist or contaminated atmospheres, therefore, supplemental protection must be provided to prevent the development of electrical conductive paths across the relatively small insulating surfaces.
The metal shells of some solid state devices operate at the collector voltage and for some rectifiers and thyristors at the anode voltage. Therefore, consideration should be given to the possibility of shock hazard if the shells are to operate at voltages appreciably above or below ground potential. In general, in any application in which devices are operated at voltages which may be dangerous to personnel, suitable precautionary measures should be taken to prevent direct contact with these devices.
Devices should not be connected into or disconnected from circuits with the power on because high transient voltages may cause permanent damage to the devices. In common with many electronic components, solid-state devices should be operated and tested in circuits which have reasonable values of current limiting resistance, or other forms of effective current overload protection. It is desirable in all soldering operations to provide some slack or an expansion elbow in each lead, to prevent excessive tension on the leads.
It is important during the soldering operation to avoid excessive heat in order to prevent possible damage to the devices. Some of the heat can be absorbed if the flexible lead of the device is grasped between the case and the soldering point with a pair of pliers. In such cases, it is essential that the mounting flange be securely fastened to the heat sink, which may be the equipment chassis.
Under no circumstances, however, should the mounting flange be soldered directly to the heat sink or chassis because the heat of the soldering operation could permanently damage the device. Such devices can be installed in commercially available sockets. Electrical connections may also be made by soldering directly to the terminal pins. Such connections may be soldered to the pins close to the pin seals provided care is taken to conduct excessive heat away from the seals; otherwise the heat of the soldering operation could crack the pin seals and damage the device.
During operation, the mounting-flange temperature is higher than the ambient temperature by an amount which depends on the heat sink used.
The heat sink must have sufficient thermal capacity to assure that the heat dissipated in the heat sin k itself does not raise the device moun tingflange temperature above the rated value.
The heat sink or chassis may be connected to either the positive or negative supply. If the recommended mounting hardware shown in the data bulletin for the specific solid-state device is not available, it is necessary to use either an anodized aluminum insulator having high thermal conductivity or a mica insulator between the mounting-flange and the chassis.
The burrs should then be removed from the washer and the washer anodized. To insure that the anodized insulating layer is not destroyed during mounting, it is necessary to remove the burrs from the holes in the chassis. It is also important that an insulating bushing, such as glass-filled nylon, be used between each mounting bolt and the chassis to prevent a short circuit. However, the insulating bushing should not exhibit shrinkage or softening under the operating temperatures encountered.
Otherwise the thermal resistance at the interface between transistor and heat sink may increase as a result of decreasing pressure. The following paragraphs provide guidelines for handling and mounting of these plastic-package devices, recommend forming of leads to meet specific mounting requirements, and describe various mounting arrangements, thermal considerations, and cleaning methods.
This information is intended to augment the data on electrical characteristics, safe operating area, and performance capabilities in the technical bulletin for each type of plastic-package transistor or thyristor. Lead-Forming Techniqup. Although these leads can be formed, they are not flexible in the general sense, nor are they sufficiently rigid for unrestrained wire wrapping Before an attempt is made to form the leads of an in-line package to meet the requirements of a specific application, the desired lead configuration should be determined, and a lead-bending fixture should be designed and constructed.
The use of a properly designed fixture for this operation eliminates the need for repeated lead bending. When the use of a special bending fixture is not practical, a pair of long-nosed pliers may be used. The pliers should hold the lead firmly between the bending point and the case, but should not touch the case. When the leads of an in-line plastic package are to be formed, whether by use of long-nosed pliers or a special bending fixture, the folloWing precautions must be observed to avoid internal damage to the device: Restrain the lead between the bending point and the plastic case to prevent relative movement between the lead and the case.
When the bend is made in the plane of the lead spreading , bend only the narrow part of the lead. Avoid repeated bending of leads. Force in this direction greater than 4 pounds may result in permanent damage to the device. If the mounting arrangement tends to impose axial stress on the leads, some method of strain relief should be devised. Wire wrapping of the leads is permissible, provided that the lead is restrained between the plastic case and the point of the wrapping.
Soldering to the leads is also allowed. When wires are used for connections, care should be exercised to assure that movement of the wire does not cause movement of the lead at the lead-to-plastic junctions. The leads of RCA molded-plastic high-power packages are not designed to be reshaped. However, simple bending of the leads is pe,mitted to change them from a standard vertical to a standard horizontal configuration, or conversely.
Bending of the leads in this manner is restricted to three degree bends; repeated bendings should be avoided. NR A is recommended to minimize distortion of the mounting flange. Excessive distortion of the flange could cause damage to the transistor.
The washer is particularly important when the size of the mounting hole exceeds 0. Larger holes are needed to accommodate insulating bushings; however, the holes should not be larger than necessary to provide hardware clearance and, in any case, should not exceed a diameter of 0. Flange distortion is also possible if excessive torque is used during moun ting. A maximum torque of 8 inch-pounds is specified.
Care should be exercised to assure that the tool used to drive the mounting screw never comes in contact with the plastic body during the driving operation. Such contact can result in damage to the plastic body and internal device connections. An excellent method of avoiding this problem is to use a spacer or combination spacer-isolating bushing which raises the screw head or nu t above the top surface of the plastic body. The material used for such a spacer or spacer-isolating bushing should, of course, be carefully selected to avoid "cold flow" and consequent reduction in mounting force.
Suggested materials for these bushings are diallphtalate, fiberglass-filled nylon, or fiberglass-filled polycarbonate. Unfilled nylon should be avoided. Modification of the flange can also result in flange distortion and should not be attempted. The transistor should not be soldered to the heat sink by use of lead-tin solder because the heat required with this type of solder will cause the junction temperature of the transistor to become excessively high. Socket No. PTS4 or equivalent.
DC or equivalent. Regardless of the mounting method, the following precautions should be taken: Use appropriate hardware. Always fasten the transistor to the heat sink before the leads are soldered to fixed terminals.
Never allow the mounting tool to come in contact with the plastic case. Never exceed a torque of 8 inch-pounds. Avoid oversize mounting holes. Provide strain relief if there is any probability that axial stress will be applied to the leads.
Use insulating bushings to prevent hot-creep problems. Such bushings should be made of diallphthalate, fiberglass-filled nylon, or fiberglass-filled polycarbonate. The maximum allowable power dissipation in a solid state device is limited by the junction temperature. When a solid state device is operated in free air, without a heat sink, the steady-state thermal circuit is defined by the junction-to-free-air thermal resistance given in the published data for the device.
Thermal considerations require that a free flow of air around the device is always present and that the power dissipation be maintained below the level which would cause the junction temperature to rise above the maximum rating.
However, when the device is mounted on a heat sink, care must be taken to assure that all portions of the thermal circuit are considered.
To assure efficient heat transfer from case to heat sink when mounting RCA molded-plastic solid state power devices, the following special precautions should be observed: Mounting torque should be between 4 and 8 inchpounds. The mounting holes should be kept as small as possible. Holes should be drilled or punched clean with no burrs or ridges, and chamfered to a maximum radius of 0.
The mounting surface should be flat within 0. Thermal grease Dow Corning or equivalent should always be used on both sides of the insulating washer if one is employed. Thin insulating washers should be used. Thickness of factory-supplied mica washers range from 2 to 4 mils. A lock washer or torque washer, made of material having sufficient creep strength, should be used to prevent degradation of heat sink efficiency during life. A wide variety of solvents is available for degreasing and flux removal.
The usual practice is to submerge components in a solvent bath for a specified time. However, from a reliability stand point it is extremely important that the solvent, together with other chemicals in the solder-cleaning system such as flux and solder covers , do not adversely affect the life of the component.
This consideration applies to all non-hermetic and molded-plastic components. It is, of course, impractical to evaluate the effect on long-term transistor life of all cleaning solvents, which are marketed with numerous additives under a variety of brand names. These solvents can, however, be classified with respect to their component parts, as either acceptable or unacceptable.
Chlorinated solvents tend to dissolve the outer package and, therefore, make operation in a humid atmosphere unreliable. Gasoline and other hydrocarbons cause the. Alcohol and unchlorinated freons are acceptable solvents. Examples of such solvents are: Freon TE 2.
Freon TE 3. Rosin or activated rosin fluxes are recommended, while organic or acid fluxes are not. Examples of acceptable fluxes are: Alpha Reliaros No. Alpha Reliafoam No. Kester No. A surge-limiting impedance should always be used in series with silicon rectifiers and thyristors. The impedance value must be sufficient to limit the surge current to the value specified under the maximum ratings.
This impedance may be proVided by the power transformer winding, or by an external resistor or choke. A very efficient method for mounting thyristors utiliZing packages such as the JEDEC TO-5 and "modified TO-5" is to provide intimate contact between the heat sink and at least one half of the base of the device opposite the leads. These packages can be mounted to the heat sink mechanically with glue or an epoxy adhesive, or by soldering. Soldering to the heat sink is preferable because it is the most efficient method.
The use of a "self-jigging" arrangement and a solder preform is recommended. If each unit is soldered individually, the heat source should be held on the heat sink and the solder on the unit. Heat should be applied only long enough to permit solder to flow freely. Emerson and Cumming, Inc. With proper handling and applications procedures, however, MOS transistors are currently being extensively used in production by numerous equipment manufacturers in military, industrial, and consumer applications, with virtually no problems of damage due to electrostatic discharge.
These diodes offer protection against static discharge and in-circuit transients without the need for external shorting mechanisms. Polystyrene insulating "SNOW" is not sufficiently conductive and should not be used. When devices are removed by hand from their carriers, the hand being used should be grounded by any suitable means, for example, with a metallic wristband. Tips of soldering irons should be grounded. Devices should never be inserted into or removed from circuits with power on.
In any method of mounting integrated circuits which involves bending or forming of the device leads, it is extremely important that the lead be supported and clamped between the bend and the package seal, and that bending be done with care to avoid damage to lead plating.
In no case should the radius of the bend be less than the diameter of the lead, or in the case of rectangular leads, such as those used in RCA lead and lead flat-packages, less than the lead thickness. All transmission gate inputs and all outputs have diode protection prOVided by inherent p-n junction diodes. Although protection against electrostatic effects is provided by built-in circuitry, the following handling precautions should be taken: Soldering-iron tips and test equipment should be grounded.
Devices should not be inserted in non-conductive containers such as conventional plastic snow or trays. All unused input leads must be connected to either VSS or VDD, whichever is appropriate for the logic circuit involved. A floating input on a high-current type, such as the CDA, CD40IOA, not only can result in faulty logic operation, but can cause the maximum power dissipation of milliwatts to be exceeded and may result in damage to the device.
Inputs to these types, which are mounted on printed-circuit boards that may temporarily become unterminated, should have a pull-up resistor to VSS or VDD. A useful range of values for such resistors is from 0. Input Signals Signals shall not be applied to the inputs while the device power supply is off unless the input current is limited to a steady state value of less than 10 milliamperes.
Output Short Circuits.
In general, these types can all be safely shorted for supplies up to 5 volts, but will be damaged depending on type at higher power-supply voltages. For cases in which a short-circuit load, such as the base of a p-n-p or an n-p-n bipolar transistor, is directly driven, the device output characteristics given in the published data should be consulted to determine the requirements for a safe operation below milliwatts.
Solid state chips, unlike packaged devices, are nonhermetic devices, normally fragile and small in physical size, and therefore, require special handling considerations as follows: After the shipping container is opened, the chip must be stored under the following conditions: Storage temperature, C max.
Clean, dust-free environment. The user must exercise proper care when handling chips to prevent even the slightest physical damage to the chip. During mounting and lead bonding of chips the user must use proper assembly techniques to obtain proper electrical, thermal, and mechanical performance.
After the chip has been mounted and bonded, any necessary procedure must be followed by the user to insure that these non-hermetic chips are not subjected to moist or contaminated atmosphere which might cause the development of electrical conductive paths across the relatively small insulating surfaces.
In additior. Burke and G. Albrecht Silicon controlled rectifiers SCR's are often used in pulse circuits in which the ratio of peak to average current is large. Typical applications include radar pulse modulators, inverters, and switching regulators. The limiting parameter in such applications often is the time required for forward current to spread over the whole area of the junction.
Losses in the SCR are high, and are concentrated in a small region until the entire junction area is in conduction.
This concentration produces undesirable high temperatures. The negative voltage reverse-biases the SCR. When the energy-storage network is recharged from the dc supply, the SCR returns to the forwardblocking condition and is ready foc the next cycle. The recharge interval t3 - t4 may be delayed by use of a charging SCR, as shown in Figs. This technique reduces the turn-off time requirements for the SCR. A common requirement would be to pass focward currents with particular emphasis on shape and magnitude.
TurnOn Time Definitions. A typical SCR pulse modulator circuit is shown in Fig. Basic waveforms for the circuit are shown in Fig. The capacitors of the energy-storage network are charged by the dc supply.
The SCR is triggered by pulses from the gate-trigger generator No. For turn-off, the load is "mismatched" to the discharge-circuit impedance so that a negative voltage is developed on the capacitor at the end of the pulse. In the idealized waveforms of Fig. Actually, it exhibits a finite resistance prior to turn-on, a delay after the introduction of the trigger pulse, and appreciable resistance after turn-on.
The common definition of turn-on time adequately covers the delay and rise-time intervals of the turn-on process, but does not consider the rate of current spread over the junction area and its attendant dissipation. Because the dissipation after turn-on is an important consideration in pulse circuits, turn-on definitions in themselves provide no indication of the switching capability of the SCR. Because several different physical effects occur in the SCR during the complete turn-on interval, it is convenient to divide the total turn-on time into three discrete intervals: The sol id lines represent device turn-on to low steadystate forward current, in which case equalization effects are not pronounced.
The dashed lines represent SCR turn-on to high currents, in which case t3 becomes a noticeable interval. The first interval tl or delay time results from the initiation of forward conduction between the p-type base and the n-type emitter i. This interval depends to a Iarge extent upon the level of gate current used to turn on the SCR. The use of a trigger pul se greater than the min imum gate-current requirement of the SCR minimizes delay time and reduces the range of the delay times encountered between individual SeR's, the variability of delay with temperature, and the variability of cycle-to-cycle delay or jitter.
The del ay interval is primarily of interest because of its effect on system perfonnance. As an example, the rise-time portion of turn-on is defined as the time interval between the per-cent and per-cent points on the current wave shape when the SCR is triggered on in a circuit that has rated forward voltage and sufficient resistance to limit the current to rated values.
For a volt device, the end of the turn-on interval occurs when the forward voltage drop across the SCR is 60 volts. This value contrasts with the steady-state forward voltage of only 1 or Z volts under such conditions. An interval many times greater than the turn-on time may be -required before the forward voltage drop reduces to the steady-state level. The second interval tz or fall time depends on the initiation of forward conduction between the p-type emitter and the n-type emitter i.
When this phenomenon is isolated from current ef'gcts, as described later, the duration of the voltage fall time measured from the 9O-per-cent to the per-cent point is less than 0. Voltage fall time is illustrated in Fig. The flow of forward current during the voltage fall time results in power loss in this interval.
The magniI I. The technical bulletin for the S Mcontains infonnation on maximum trigger-pulse magnitudes for various pulse widths for this device.
The third discrete interval during turn-on, equalization time t3 of Fig. The forward current resulting from the initial voltage fall is concentrated in a small area of the junction and spreads gradually over the entire area.
The rate of increase in the active j unction area depends on the geometry and the junction parameters, and is infll!
In general, the time required for full utilization of junction area represents a considerably longer interval than tl delay or tz fam. This curve, together with those in Figs. IO illustrates the calculation of device dissipation and pulse repetition rate for a particular pulse. For given conditions of current rise time, current level, and gate drive, t3 could be defined as the time required for forward voltage to decrease to a given multiple of the final steady-state value under a constant-current pulse.
Such a definition would be more indicative of switching capability than the conventional definition of turn-on time as the time required for forward ON-state voltage to decrease to a percentage of the initial blocking voltage.
At best, however, either type of definition has only limited usefulness to the user.
Limits must also be imposed upon the instantaneous temperature rise of the junction over the average case. For a repetition rate of pulses per second, the average forward dissipation is This value is within the rating of 30 watts for the S I M at a case temperature.
Peak current as a function of maximum repetition rate for square-wave pulse shapes. At higher case temperatures the total dissipation must be decreased, as shown in Fig. In the example shown, the pulse has a peak magnitude of amperes and a base width of 5 microseconds. The curves shown in Fig.
IO are constructed from the curves of Figs. Because the interval of highest dissipation occurs at the beginning of the current pulse, reduction in the magnitude of current during this time increases the over-all switching capability of the SCR. The current is then small, and dissipation is limited, until the junction area in conduction increases to incl ude an appreciable percentage of the total cathode. By the time the reactor saturates and high pulse current results, the cathode.
The rate of current spread over the cathode area depends upon several factors, one of which is the level of current. Therefore, the use of a delay reactor to keep forward current low also delays the spread of current to some extent and subtracts from its beneficial effects. The maximum benefit can be achieved by reduction of the inductance of the reactor prior to saturation, or by addition of another impedance in parallel with the reactor, to effect a compromise between the initial current level and dissipation and the rate of current-density equalization.
The curves in thi s Note do not represent the use of a delayreactor. In addition to the power loss in the SCR caused by forward current, the total dissipation in the device includes forward and reverse blocking losses and probably reverse recovery losses during the turn-off process. The reverse recovery losses depend upon several factors, such as forward-current amplitude, rate of decrease of forward current, reverse-current flow, rate of rise of reverse voltage, and reverse-voltage amplitude.
Because reverse losses are circuit-dependent, they can best be evaluated in a working circuit. Silicon controlled rectifiers have been widely accepted in power-control applications in industrial systems where high-performance requirements justify the economics of the application. Historically, in the commercial high-volume market, economic considerations have precluded the use of the SCR. However, with the development of a family of SCR's by RCA designed specifically for mass-production economy and rated for and volt line operation, the use of these devices in controls for many types of small electric motors has been made economically feasible.
The controls can be designed to provide good performance, maximum efficiency, and high reliability in compact packaging arrangements. The control circuits discussed in the following text are typical of the many possible circuits applicable to electric motor control.