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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Report discusses number of tests used in comparing polymer adhesives with metal bonding processes and includes charts and photographs to illustrate test results. Findings suggest reduced quality control costs when epoxies are used in fabrication of microcircuits.
Resin systems for coating hybrids prior to hermetic sealing are described. The resin systems are a flexible silicone junction resin system and a flexible cycloaliphatic epoxy resin system. The coatings are intended for application to the hybrid after all the chips have been assembled and wire bonded, but prior to hermetic sealing of the package. The purpose of the coating is to control particulate contamination by immobilizing particles and by passivating the hybrid. Recommended process controls for the purpose of minimizing contamination in hybrid microcircuit packages are given. Emphasis is placed on those critical hybrid processing steps in which contamination is most likely to occur.
Thin and thick film test specimens were utilized to study the effects of silicone and epoxy hybrid microcircuit coatings on 0.025 mm diameter aluminum and gold ultrasonic bonds, and 0.051 diameter gold pulsed-thermocompression bonds. Chip-to-substrate and substrate-to-substrate geometries were included. Because sealed packages were utilized, a test pattern design was incorporated that allowed the determination of bond failures by making resistance measurements external to the package after the various environmental tests. All wire bonds were non-destructively pull tested prior to sealing. Tests included the PIN test, temperature cycling, and high temperature storage.
Hybrid-microcircuit masking technique improved to prevent unwanted parylene coating of lead packages.
The reliability of hybrid microcircuits has been enhanced in recent years by the use of organic adhesives as a replacement for solder and eutectics. The epoxies have been the most effective and widely used material for this application. Methods for measuring the electrical and mechanical properties of epoxies are developed. Data are given for selected conductive adhesives at high and low frequencies. The temperature coefficients of resistance of thick film resistors are presented.
Software development methods have been investigated and two test bed projects have been chosen to evaluate application techniques of the 8080A and support microcircuits which will satisfy DSN requirements. Final recommendations will reflect successful JPL applications experience.
Calibrated set of microcircuit packages containing tiny particles with known masses can be used as reference standards for Particle-Impact Noise-Detection (PIND) tests.
Recent study on Particle-Impact Noise-Detection (PIND) shows impact at 1,500 to 4,000 G normally imparted to hybrid microcircuits during testing knocks loose stray trapped particle that can be subsequentially removed. Process may be 80 to 90 percent effective in removal of particles depending on type of test utilized.
A family of standard, high-reliability hardware used for packaging digital integrated circuits is described. The design transition from early prototypes to production hardware is covered and future plans are discussed. Interconnections techniques are described as well as connectors and related hardware available at both the microcircuit packaging and main-frame level. General applications information is also provided.
Hybrid microcircuits were examined in regard to their place in the electronic packaging spectrum. The problem of why hybrids are not as widely used as they should be is addressed as the primary concern.
Tape automated bonding (TAB) shows promise of being the predominant assembly and interconnect technique for microcircuit devices in the 1980's. After briefly reviewing the evolution of TAB, consideration was given to factors influencing and motivating TAB, including current major problem areas. Solutions to these problems are being investigated under five Department of Defense programs. These complementary efforts are discussed and compared. The findings are contrasted against recent improvements and advancements in automated wire bonding.
A design analysis of a high density multilevel thick film digital microcircuit used for large scale integration is presented. The circuit employs 4 mil lines, 4 mil spaces and requires 4 mil diameter vias. Present screened and fired thick film technology is limited on a production basis to 16 mil square vias. A process whereby 4 mil diameter vias can be fabricated in production using laser technology was described along with a process to produce 4 mil diameter vias for conductor patterns which have 4 mil lines and 4 mil spacings.
The results of a study on Particle Impact Noise Detection commonly referred to as PIND testing is described. Certain sensitivities of PIND testing as applicable to hybrid microcircuits were determined, and techniques for removing particles from sealed hybrid packages were evaluated. Methods for freeing particles which have become trapped or hung up inside the hybrid package and, therefore, give no PIND test response were examined.
Those factors affecting the cost of electronic subsystems utilizing LSI microcircuits were determined and the most efficient methods for low cost packaging of LSI devices as a function of density and reliability were developed.
Twenty-five Hughes HCMP 1852D and 25 RCA CDP1852D 8-bit, CMOS, I/O port microcircuits underwent electrical characterization tests. All electrical measurements were performed on a Tektronix S-3260 Test System. Before electrical testing, the devices were subjected to a 168-hour burn-in at 125 C with the inputs biased at 10V. Four of the Hughes parts became inoperable during testing. They exhibited functional failures and out-of-range parametric measurements after a few runs of the test program.
Report discusses mathematical models used to estimate costs of developing and fabricating microcircuits. Second part discusses LSI packaging using tape chip carrier technology.
Feasibility study looks at effectiveness of silicon nitride passivation coating against moisture and mobile ions. Coating was tested on CMOS microcircuits. Tests included temperature cycling, high-temperature electrical stress, and temperature and humidity exposure. Report concludes plastic-encapsulated circuits with protective coating exhibit high survival rates; it includes tables summarizing test results and figures that show effects of flexing.
The collection and analysis of data concerning intermittent dailures in digital devices was performed using data from a computer design for shipboard usage. The failure data consisted of actual field failures classified by failure mechanisms and their likelihood of having been intermittent, potentially intermittent, or hard. Each class was studies with respect to computer operation in the ranges of 0 to 2,000 hours, 0 to 5, hours, and 0 to 10,000 hours. The study was done at the computer level as well as the microcircuit level. Results indicate that as age increases, the quasi-intermittent failure rate increases and the mean time to failure descreases.