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The effort reported covers the first phase of a program of developments leading to the integration of long life, insulated, thermionic converters with efficient, constant temperature, heat transfer devices. The report details the investigations which demonstrated reliability of thermionic modules by life test and of high temperature ceramic-to-metal seals. An improved module was designed for operation up to 1500 C. Special investigations were conducted to improve performance by use of high purity cesium, the addition of inert gases, and the development of low work function collectors. High temperature insulation was developed and evaluated to 1600 C. A cast ceramic was employed electrically insulate the emitter from the heat source and still maintain high thermal conductivity. A high temperature converter, Type A-1198C was developed which operated successfully for more than 500 hours from thermal power supplied by means of a heat pipe. Extensive investigation was employed to design the heat pipe for this particular application. The program included evaluation of processing and closure techniques, the development of capillary structures and the determination of methods for supplying the thermal input. Prototype heat pipes were fabricated and tested for operation to 1500 C, temperature uniformity within 5 degrees over the length of the heat pipe, capability to deliver 50 w/sq cm at the converter emitter and operation for a minimum of 500 hours. (Author)

Circuit design and masks for the R-C circuit vehicle have been completed, as well as processing of the adapter network and special control pattern. Analysis of data and failure from the first run of the adapter are included. Processing of samples for Phase II is in progress. Further study is planned in the areas of contacting cermet resistors, deposition of nichrome, substrate cleanliness, aluminum silicate capacitor process and glow discharge anodization of capacitors. (Author)

This report presents an approach toward attaining high life test reliability in subminiature ceramic barium titanate capacitors for transistor circuitry and demonstrates a procedure for selecting capacitors having guaranteed or assured lifetime (ALT) at various voltage and temperature stresses. The report presents the research supporting the plan of voltage selection testing which identifies those capacitors that have an assured useful lifetime (ALT). Other selection plans were surveyed but were rejected. The physics of material failure and reliability is discussed. Two lots of 1200 capacitors (0.01 microfarads and 0.033 microfarads) were voltage tested to identify capacitors which were predicted to fail life testing either prior to ALT or after ALT. Life testing was as long as 25,000 hours at several voltage and temperature conditions. The failure rate, after normalizing data, at 125 C, 25 VDC to ALT (30,300 hours) for the select 0.01 microfarads capacitors was 0. 02% per 1000 hours. The failure rate after normalizing data at 125 C, 25 VDC to ALT (4775 hours) for the select 0.033 microfarads capacitors was 0.086% per 1000 hours. The failure rates to ALT for capacitors predicted to fail prior to ALT exceeded the failure rates of the select capacitors by factors approaching 100.

This report presents a survey of ceramic systems exhibiting ferroelectricity together with fundamental data on ferroelectric crystals. A review of the basic reasons for the occurrence of ferroelectricity as well as for the dependence of the ferroelectric transitions and the properties of ferroelectric materials on the intensive parameters follows. The dielectric, piezoelectric and elastic properties of experimental and commercially available ceramic ferroelectrics are listed. The interpretation of dielectric properties of ceramic ferroelectrics as modified single-crystal properties includes a discussion of dielectric constant, stability, non-linear behavior and domain effects. Techniques for poling and special forming methods for ferroelectrics are described followed by a discussion of the linear and non-linear devices employing ferroelectric materials.

Testing of C67 Case Size I Monolythic capacitors of the improved version continues to demonstrate the long-life capability of this capacitor at use conditions. The testing of 124 of these capacitors at 200 VDC and 125 C for 2500 hr without catastrophic failure, then at 400 VDC and 125 C for 4000 hours with only five displaying any degradation, continues to indicate the intrinsic high reliability of this unit.

A detailed discussion on the results of pre-matrix I testing is presented. Data and graphs are included. This pre-matrix work has been centered about an effort to predict the life of a capacitor by measuring its discharge current. Among the relationships examined in the course of this study are those between: (1) resistance and temperature; (2) initial resistance and time to failure; (3) initial resistance symmetry and time to failure; and (4) intermediate resistance and time to failure.

See also Volume 1, AD-A952 903.

There appears to be a relationship between first firing conditions and fluoride tolerance. It is anticipated that experiments in short firing cycles will result in a more simplified fluorina tion technique. Chemical analysis of fluorine content in fluorinated dielectrics has been performed by TAM and is contained in this report. Variations in F content are possibly related to first firing techniques. Dipped encapsulants capable of withstanding 200 C and providing good terminal support are being tested. The use of pre- molded cases is considered and will be evaluated. Pre-production samples have been fluorinated and no difficulty is anticipated during qualification testing.

The method of electroding was changed from transfer wheel to silk screening during the reporting period. The operation of the silk screen machine was evaluated and sample units were, and are being, made using the existing equipment. These units are being evaluated to check the performance of the different pieces of equipment.

Efforts were directed toward a production engineering measure for subminiature temperature compensating ceramic capacitors. The temperature coefficient of capacitance (TC) requirement for the NP0 capacitors was achieved as a result of work during this period. A recapitulation of areas investigated in the study leading to this attainment is presented herein. Approval of the Case Size III qualification samples was received, and pilot production on the three formulations of this case size will begin as soon as authoriza on is received. The status of pilot production for Case Sizes I and II is given in this report.

Life testing of ceramic disks of (Ba.97La.02)ZrO3, Ba.99(Zr.98Nb.02)O3 and La(Al.96Si.03)O3 at 350 C for 1000 hr was terminated. During this period a field of 60 v-dc/mil was applied continuously. Of these materials the (Ba.97La.02)ZrO3 disks stood the test successfully. The final values for individual disks were between 10 to the 9th power and 10 to the 11th power ohm-m for volume resistivity and between 2 and 90 megohm-microfarad for (RC)-products. The other materials failed by puncture, rupture or excessive drop of volume resistivity. The electrical properties of ceramics of (Ba.94La.04)ZrO3 and (Ba.91La.06)ZrO3 were determined from 250 to 500 C. The dielectric constants are about 38 at 250 C and diminish to about 36 at 500 C. The volume resistivity values are of the order of 10 to the 11th power at 250 C and 10 to the 7th power at 500 C. The dielectric quality factor at 250 degrees is nearly 2000 for (Ba.94La.04)ZrO3 and almost 1000 for (Ba.91La.06)ZrO3. The corresponding values at 500 C are close to 150 for both. (Author)

Radiation testing of ceramic, glass, tantalum, mica, polystyrene, and mylar capacitors is complete. Data analysis is not complete. New effects were observed when testing glass and tantalum capacitors. Leakage currents in irradiated thin film resistors are principally due to secondary emission and air ionization. No data errors were detected on a magnetic tape that was irradiated. Dosimetry techniques are described, and errors in previous linac dosimetry are discussed. (Author)

The report describes the radiation-induced behavior of tantalum-oxide, mica, ceramic, Mylar, glass, and polystyrene capacitors using results obtained at several sources. Also included are discussions of the following: Experimental techniques at each radiation source, including measurement of circuits, components, dosimetry, and variation of circuit and radiation parameters; Results from SPRF, LINAC, and AFXR tests describing the dependences of the induced current for the irradiated dielectric; Interpretation of these results in terms of appropriate models and radiation and circuit parameters; Comparison of the effects observed at each irradiation source; Description of the tests on magnetics and the test results. (Author), See also AD-616 007.

A detailed description of the techniques and equipment employed in the ion-implantation process is presented. Results of high-energy electron irradiation of a Mylar capacitor with ion-implanted electrodes are compared to the response of a control sample. The ion-implanted electrodes exhibit better carrier injection than conventional foil electrodes. Transient radiation effects data from irradiation of a monolithic ceramic capacitor and two glass capacitors are included. One of the glass capacitors contained a semicrystalline dielectric with very high dielectric constant. The transient radiation effects in Mylar versus temperature appear to fit a band model for the conduction process in which a continuous distribution of carrier traps is located in the forbidden zone and one sign of carrier is immobilized. An examination of the energy loss processes of moderately fast electrons in insulators indicates that from 15 eV to 3 eV the energy loss is primarily to excitons whereas energy loss to optical and acoustical phonons occurs down to thermal energies. (Author), See also AD-626 474.

During the contract year a degree of correlation between the field and laboratory stress environments, as reflected through changes in component characteristics was accomplished. Since the correlation studies are as yet incomplete, detailed information will be provided in future reports. The specified MIL-STD-2O2O Method 106B 20-cycle temperature and humidity stress environment was found to yield correlation with certain jungle exposed components. From the 6-l8-64 Phase I groups, these were composition resistors, carbon film resistors, wire wound resistors, Mylar capacitors, and mica capacitors. From the 9-2l-65 Phase II component groups, correlation was observed for the cermet variable resistor on a failure only basis. The variable ceramic capacitor has exhibited failure in the field environment, but not in the laboratory environment. None of the remaining exhibited a failure mechanism and field data are considered premature at present for a correlation analysis based upon degradation. One very significant indication of both field and laboratory stressing is that correlation will be based primarily upon degradation rather than failure. The specified laboratory test does not in any way provide the stress and corrosion effects of the airborne salt and dust present at the tropical seashore exposure site. It is the conduction of this surface that has yielded data which do not faithfully represent the performance of certain high impedance components.

This program has established that polycrystalline films of bismuth titanate, rf-sputtered from a dielectric target, possess electrical and chemical properties allowing their use in solid state circuits. When used in the context of large area micro-strip circuits, the films yield low effective loss (approximately 1%) and provide an effective relative dielectric constant of 190 + or - 30 for the 1 to 12 GHz frequency range. Extension of these results suggests that the material could be used for microwave circuit by-pass capacitors in which extremely low loss is not required. A major achievement of the present effort has been the improvement of both dielectric withstanding voltage and etching behavior by annealing in oxygen. Such treatment appears to suppress conduction thought to occur along metal-rich grain boundaries. Annealing increases the etch ratio in HCl of as-prepared polycrystalline films by factors of 4 to 10 to values like those for epitaxial material. This relieves, but does not obviate, the problem of undercutting of protected regions which is a peculiarity of the titanate films. As a demonstration of the applicability of sputtered Bi4Ti3O12 films in silicon integrated technology, insulated gate field effect transistors were fabricated using the material as the gate dielectric. In these devices, a thin layer of chemical vapor deposited SiO was used to improve the adhesion of aluminum to the titanate. (Author)

The bibliography is a compilation of unclassified-unlimited references on Capacitor Technology. This report presents information on miniature and microelement capacitors formed by deposition of dielectric substance on a ribbon, sheet, or wafer, and discrete capacitive elements which are found in monolithic or integrated circuits and serve to integrate with other similarly constructed passive and active elements to function as a complete electronic circuit. Corporate Author/Monitoring Agency, Subject, Title, and Personal Author Indexes are included. (Author), Supersedes AD-691 400.

IC CAPACITORS, ELECTROLYTESGuidelines were established to facilitate the selection of high-value capacitors for ordnance fuzing and other military applications. Background information has been compiled on the electrical and physical properties of ceramic capacitors rated to 10 microfarads and electrolytic capacitors rated in thousands of microfarads, either of which is also available in ratings below one microfarad. Standard dc working voltages range from 25 to 1000 volts for the ceramics and from 6 to 600 volts for the electrolytics. Since the report is concerned primarily with fuzing applications, only the high-K ceramic and tantalum dielectric capacitors are discussed in any detail. The high-voltage ceramics and aluminum electrolytics are included mainly for comparison. (Author)

Using HDL-developed deposition techniques, six film twin-T filters were fabricated consisting of alloy film resistors and silicon oxide capacitors. The filters oscillated in the range 1000 to 4400 Hz and displayed temperature coefficients less than 100 ppm/(degree C). Fabrication techniques are discussed along with planned changes necessary to meet HDL requirements for small, temperature-stable oscillators. (Author)

Contents: Semiconductors and their role in modern technology; Thermistors and their fields of application; The choice of operating regimes for semiconductor thermistors; Certain types of semiconductor thermistors; Indirectly heated thermistors; Practical experience with thermistors of types ShT-1 and T-8; The application of semiconductors in computers for the construction of functional quadrupoles; Photoresistors and their basic parameters; PbO photoresistors; Metallurgical photoresistor photorelays; Applications of the hall effect in semiconductors; Experimental examination of detector-type current-measuring devices using point-contact and planar germanium diodes; Some possibilities of temperature self-compensation in rectifier voltmeters; Protective and automation relays using semiconductor rectifiers; Modulation of infrared rays by electric current in a germanium diode; Thermoelectric cooling and its use in instrument design; Variconds and their field of application; An investigation of the operation of variconds., Trans. of Mono. Primeneniye Poluprovodnikov v Priborostroyenii, Moscow, 1958, 259p.

The report shows that the characteristics of thin film capacitors utilizing aluminum electrodes and SiO dielectrics can be improved by annealing at 450C. Some indication is given to the effects of various process parameters during dielectric deposition and supports the general concensus that consistently good thin film capacitors are rather difficult to fabricate. (Author)

Gradual changes in experimental and commercial Ti02 and BaTi03 bodies upon application of DC-stresses at high temperatures were observed and measured during and after the test. The changes in resistivity are sometimes accompanied by changes in capacity, loss factor and color. The current producing these changes has the features of an absorption current: it can be partly recovered; the discharge current can be measured over very long periods of time. Investigation of the effect of the electrode material on all changes occurring reveals that only the electrode material at the anode has an influence on the sign and on the rate of the change. Humidity has a very detrimental effect upon some dielectrics. Treatment in a humid atmosphere at 1000C stores protons in some form in the material; these protons become activated during life test and produce rapid degradation. After removal from the DC life test, the changes produced by the DC stress disappear and the sample might recover completely, if the degradation damage has not been too severe. There are also chemical means to prevent the entering and migration of the two mobile defects. (Author), Continuation of Contract DA-36-039-AMC-00107(E).

Variconds permit a stabilization of the voltage for an asynchronous generator in the entire range of its load changes. The use of an contactless asynchronous generator, in the system, makes it reliable and convenient in operation. (Author), Unedited rough draft trans. of Elektrotekhnika (USSR) v35 n11 p41-4 1964.

The effects of reactor radiation and LINAC irradiation on the dielectric properties of several common capacitors are compared. The dependence of the induced currents generated on applied voltage, geometry, dose, and dose-rate, is contrasted for mylar, polystyrene, mica, tantalum, glass, and ceramic capacitors. These effects are analyzed in terms of models appropriate for the various capacitors and their associated parameters are defined. Induced currents in irradiated thin-film resistors are principally due to secondary emission and air ionization. Static tests of ferrite core memory planes and magnetic tape were conducted at LINAC. The purpose was to determine whether these materials would retain stored information after radiation exposure. (Author)

The purpose of this study was to produce coherent stimulated emission in the blue-green region in a purely organic dopant and host system. Toward this end, a theoretical analysis of the problem was made and experimental work on the development of such a laser was done. The theoretical analysis indicates that the short lived four-level fluorescent compounds are the most suitable materials for this purpose. The principal experimental difficulties included the development of a suitable host material in which the absorbing and scattering losses are kept to a minimum and an optical pump system capable of efficiently producing several megawatts of absorbable peak power in a short time. Some gain at 4710 Angstroms in a Fabry-Perot resonant cavity was observed which is probably preoscillation superradiance. This report is divided into four major segments which includes the theoretical analysis, the materials selection and preparation, the device development, and the experimental pumping results obtained to date. (Author)

The fluorinated dielectric has passed 2000 hours of life test at 200 C with no failures. The post life measurements of dissipation factor, capacitance and insulation resistance indicate little, if any, degradational effect of the 2000 hour test. The reliability of these capacitors appears to be outstanding. The molten glass apparently dissolves a portion of the silver electrode during the glass dipping operation. This results in a capacitance loss which can be easily compensated for during silver painting operation prior to glass encapsulation. The final encapsulant of silicone rubber provides an excellent protective envelope but does not contribute toward improved terminal strength properties. (Author)

Efforts were coninued on the production engineering measure for subminiature temperaturecompensating ceramic capacitors. Efforts toward achieving Characteristic CF are continuing. Progress was made in developing spraying capability with a slip made of the N1400 formulation and the preferred binder system. Sastisfactory dipping slips made with the preferred binder system were achieved for the NPO and N750 formulations. Some progress was made in producing a satisfactory slip of the N1400 formulation and the alternate binder system. Test results from qualification testing of Group V of Case Size I units of the N1400 formulation are satisfactory. Test results from qualification testing of Case Size II units of the N1400 formulation are satisfactory to date. The cracking and strip delamination difficulties were overcome. N750 material was selected for use in the pilot run of Case Size I units. (Author)

A discussion is presented on the intrinsic reliablity program for subminiature ceramic capacitors. Investigations for the attainment of high reliability in subminiature ceramic capacitors and the determination of falure rate as a function of voltage and temperature are presented as test data. (Author)

Efforts continued on the design and construction of micro-modular electronic circuits which will equip the US Army with a broad new production potential for the construction of microminiature electronic equipment. Research is presented on the following: capacitors, resistors, inductors, semiconductor devices-transistors and diodes, crystals, micro-module reliability, communication equipment (AN/PRC-51), and the Micropac computer system.

In this failure study on capacitor-type ceramics, the past contract period has seen the emphasis shift from preparation of ceramics toward testing of the materials under electrical stress. The resistivity is given as a function of temperature for most of the ceramics. All of the materials exhibit similar behavior with respect to temperature, but there is a wide variation in magnitude among the ceramics. In general donor additions increased, and acceptor additions decreased, the resistivity at a given temperature, but the reverse held for barium stron tium titanate. Microphotographs are presented showing the grain structure of the materials. Electrical breakdown tests were also run. A general trend was found toward higher breakdown strength in ceramics having high resistivity and low dielectric constant, but there are considerable deviations from this rule in some ceramics. Long term life testing has also begun, and an example of the results is presented. (Author)

The debugging of the slip casting machine has progressed to such an extent that only minor changes are required to put it on a production basis. The tape slitting machine was installed and was operational from the start. Preproduction samples were prepared and started on test. Progress from material preparation through the tape casting operation has been such that process specifications can be written covering this segment of the operation. Initial investigation with the electrode painting and Cerol winding machines has shown that with no real major modifications these machines will work on a production basis. (Author)

Progress toward selecting ceramic formulations for use in capacitors is described. The temperature coefficient of capacitance requirement for the NP0 formulation has not yet been attained. Further work in the area of precoating ceramic powder is described. Improvements in the slicing tool, assembly jig, and electrode pickup material are reported. Frequent changes of the dipping slip have eliminated the high reject factor encountered with the NO30 formulation. Other progress in this area is noted. (Author)

Progress toward selecting ceramic formulations for use in the capacitors required under this contract was described. Attainment of the temperature coefficient of capacitance requirement for the NPO formulation remained a problem. Improved precoating of ceramic power was instituted in preparation for experimental spraying. A stable dip coating system was selected. Progress in the development of slicing, dipping, firing, edge-grinding and -abrading, electrode pickup material application, lead attachment, and assembly techniques was described. Jigs were built and underwent refinement for use in the slicing, dipping, edge-grinding and -abrading, electrode pickup material application, and assembly processes. Production personnel were being trained. (Author)

The dynamic hysteresis curve of polarized barium titanate elements has been measured in its second quadrant. This is the part of the hysteresis curve D = D(E) which goes from E = O, D = P sub o to E = E sub c, D = O, whereby the negative field -E increases from zero to E sub c within fractions of a microsecond. This part of the hysteresis curve is needed for calculations in connection with shock compression experiments on the barium titanate elements. (Author)

The patent discussed voltage-variable capacitors, including ferroelectric ceramic-dielectric capacitors that are variable by control of the potential gradients within their dielectric material. This disclosure describes voltage-variable, dielectric capacitors that have a plurality of electrodes spaced throughout the dielectric with control-voltage potentials of alternately opposing polarity to achieve a higher potential gradient within the dielectric than would be possible from a given control voltage supply to a single pair of electrodes on opposing sides of the dielectric.

The design and testing of a high power low pass filter is described. The filter has a pass band of 2 to 30 MHz and a stop band from 41 to 200 MHz. Pass band insertion loss is less than 0.3 dB and the VSWR is less than 1.4:1. The stop band rejection is greater than 60 dB. The filter is capable of operating continuously at 23 kilowatts of average power and 45 kilowatts peak power with two-tone modulation. Connection to the filter is by 3-1/8 inch EIA flanges. The low pass filter was designed for a 0.01 dB ripple Tschebyscheff response. Seventeen elements were used, eight series inductances and nine shunt capacitors. Alumina ceramic was used as the dielectric in the shunt capacitors to provide a good thermally conductive path between the center of the filter and its outer case. (Author)

The tables in this report give the response of various types of capacitors to various transient gamma radiation environments. The tables were generated on the Burroughs B5500 digital computer at Stanford University. The parameters used to characterize the capacitors were obtained from the TREE handbook (Battelle Memorial Institute, DASA 1420, Feb., 1964) and 'Analytical Methods for Predicting Transient Nuclear Radiation Effects on Electronics Circuits and Devices,' (Boeing Corp., RTD TDR-63-3007, July 1963). The capacitor parameters in these reports represent only the average response of many similar capacitors to many different radiation environments. Unit-to-unit and manufacturer-to-manufacturer variations in the capacitors make it impossible to predict the effects of radiation exactly, so these tables should be considered as giving only a 'typical' response of the particular capacitor to the given radiation environment. Assuming, however, that the capacitor parameters from the above reports are exact, then it is believed that the numbers given in the tables, with a few exceptions discussed later, are accurate to three significant figures. Additional tables are given at the end of this report. These tables give the voltage left across a capacitor at various times after t=O for a fixed resistance shorted across the capacitor at time t=O. The purpose of these tables is to help the design engineer simulate the effects of radiation., Available copy will not permit fully legible reproduction. Reproduction will be made if requested by users of DDC. Copy is available for public sale.

This report describes tests that will be performed to determine the properties of radiation-induced currents in various types of capacitors. The tests will be conducted at a linear accelerator from 13 to 17 December 1965. The report also describes tests on magnetic core memories that will be conducted at the linear accelerator during the same period. These tests are to be performed to confirm that changes in magnetic-core voltages during previous tests were not caused by irradiation. The voltage changes are believed to have been caused by the magnetic field of a vacuum pump. (Author)

A series of radiation tests has been completed on several dielectrics and magnetics at the White Sands Linear Accelerator (LINAC) Facility. Capacitors were tested at applied voltages ranging from zero to the rated values. Current probes were used to measure the induced current and replenishment charge.

Tests were made of all microelements and simulated modules after 2000-hours at 100 volts and 125C has been completed. The test data is presented., See also AD-619 880.

Experiments and studies relating to the physics of failure of barium titanate capacitors are presented. Conductivity characteristics, ionic space-charge, and mechanism of dielectric breakdown are discussed. The 10,000-hour life test matrix of the 0.01 microfarad C67 subminiature capacitor has displayed tentative statistical relationships among life times, test voltages, test temperature, and test failure criteria. An evaluation of the failure criteria was conducted. A study was made into the differences among stability and magnitude criteria. This was made for life test non-failures predicted to failures by the burn-in failure criteria, and for life test failures predicted to be failures by the criteria. Assured life times were calculated and compared to actual results of the 10,000-hour life test. (Author)

The object of this Production Engineering Measure is to improve production techniques for the manufacture of a subminiature high-reliability ceramic capacitor to attain a .001% maximum allowable operating failure rate per 1000 hours when tested at 200% of the DC rated voltage with a 90% confidence level per MIL. (Author)

Testing of C67 Case Size I capacitors of the improved version at 150 C under voltage stresses as high as 240 V/mil for 3800 hr indicates that this capacitor is intrinsically capable of extremely long life times at milder conditions of temperature and voltage. The testing of 124 of the same capacitors at 200 VDC and 125 C for 2300 hr without catastrophic failure is estimated to be equivalent to testing for 220,000,000 unit-hr at 50 VDC and 85 C without catastrophic failure. This indicates, although at a low confidence level, that this subminiature ceramic capacitor is intrinsically highly reliable. (Author)