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Investigation into environmentally friendly alternative cleaning processes for hybrid microcircuits to replace vapor degreasing with 1,1,1-trichloroethane. Final report

Description: Two cleaning processes, one aqueous and one nonaqueous, were investigated as potential replacements for the vapor degreasing process using 1,1,1 trichloroethane (TCA) for hybrid microcircuit assemblies. The aqueous process was based upon saponification chemistry. A 10% solution of either Kester 5768 or Armakleen 2001, heated to 140 F, was sprayed on the hybrid at 450 psig and a flow rate of 5 gpm through a specially designed nozzle which created microdroplets. The nonaqueous process was based upon dissolution chemistry and used d-limonene as the solvent in an immersion and spray process. The d-limonene solvent was followed by an isopropyl alcohol spray rinse to remove the excess d-limonene. The aqueous microdroplet process was found to be successful only for solder reflow profiles that did not exceed 210 C. Furthermore, removal of component marking was a problem and the spray pressure had to be reduced to 130 psig to eliminate damage to capacitor end caps. The d-limonene cleaning was found to be successful for solder reflow temperature up to 250 C when using a four-step cleaning process. The four steps included refluxing the hybrid at 80 C, followed by soaking the hybrid in d-limonene which is heated to 80 C, followed by spray cleaning at 80 psig with room temperature d-limonene, followed by spray cleaning at 80 psig with room temperature IPA was developed to remove residual flux from the hybrid microcircuits. This process was the most robust and most closely matched the cleaning ability of TCA.
Date: February 1, 1997
Creator: Adams, B.E.
Partner: UNT Libraries Government Documents Department

Characterization of an oxygen plasma process for cleaning packaged semiconductor devices. Final report

Description: The purpose of this research was to experimentally determine the operating {open_quotes}window{close_quotes} for an oxygen plasma cleaning process to be used on microelectronics components just prior to wire bonding. The process was being developed to replace one that used vapor degreasing with trichlorotrifluoroethane, an ozone-depleting substance. A Box-Behnken experimental design was used to generate data from which the oxygen plasma cleaning process could be characterized. Auger electron spectrophotometry was used to measure the contamination thickness on the dice after cleaning. An empirical equation correlating the contamination thickness on the die surface with the operating parameters of the plasma system was developed from the collected Auger data, and optimum settings for cleaning semiconductor devices were determined. Devices were also tested for undesirable changes in electrical parameters resulting from cleaning in the plasma system. An increase in leakage current occurred for bipolar transistors and diodes after exposure to the oxygen plasma. Although an increase in leakage current occurred, each device`s parameter remained well below the acceptable specification limit. Based upon the experimental results, the optimum settings for the plasma cleaning process were determined to be 200 watts of power applied for five minutes in an enclosure maintained at 0.7 torr. At these settings, all measurable contamination was removed without compromising the reliability of the devices.
Date: November 1, 1996
Creator: Adams, B.E.
Partner: UNT Libraries Government Documents Department

Development of environmentally conscious cleaning process for leadless chip carrier assemblies. Final report

Description: A cross-functional team of process, product, quality, material, and design lab engineers was assembled to develop an environmentally friendly cleaning process for leadless chip carrier assemblies (LCCAs). Using flush and filter testing, Auger surface analysis, GC-Mass spectrophotometry, production yield results, and electrical testing results over an extended testing period, the team developed an aqueous cleaning process for LCCAs. The aqueous process replaced the Freon vapor degreasing/ultrasonic rinse process.
Date: April 1, 1995
Creator: Adams, B.E.
Partner: UNT Libraries Government Documents Department

Mass Sensor

Description: The purpose of this CRADA was to use Honeywell's experience in low temperature cofire ceramics and traditional ceramics to assemble a relatively low-cost, mass-producible miniature mass analyzer. The specific design, given to us by Mass Sensors, LLC, was used to test for helium. The direct benefit for the participant was to have a prototype unit assembled for the purpose of proof of concept and the ability to secure venture capital investors. From that, the company would begin producing their own product for sale. The consumer/taxpayer benefits come from the wide variety of industries that can utilize this technology to improve quality of life. Medical industry can use this technology to improve diagnostic ability; manufacturing industry can use it for improved air, water, and soil monitoring to minimize pollution; and the law enforcement community can use this technology for identification of substances. These are just a few examples of the benefit of this technology. The benefits to DOE were in the area of process improvement for cofire and ceramic materials. From this project we demonstrated nonlinear thickfilm fine lines and spaces that were 5-mil wide with 5-mil spaces; determined height-to diameter-ratios for punched and filled via holes; demonstrated the ability to punch and fill 5-mil microvias; developed and demonstrated the capability to laser cut difficult geometries in 40-mil ceramic; developed and demonstrated coupling LTCC with standard alumina and achieving hermetic seals; developed and demonstrated three-dimensional electronic packaging concepts; and demonstrated printing variable resistors within 1% of the nominal value and within a tightly defined ratio. The capability of this device makes it invaluable for many industries. The device could be used to monitor air samples around manufacturing plants. It also could be used for monitoring automobile exhaust, for doing blood gas analysis, for sampling gases being emitted by volcanoes, for studying ...
Date: January 18, 2001
Creator: Adams, B.E.
Partner: UNT Libraries Government Documents Department

Development work on a new package design for the next generation microelectronics. Final report

Description: AlliedSignal and Micro-Mode Products joined under a DOE CRADA to develop a new package for next-generation electronics devices. Requirements included low cost of manufacture, ability to satisfy thermal expansion requirements, ability to satisfy thermal dissipation requirements, acceptable digital and microwave performance, and hermeticity. Four processes were tested; vacuum deposition of paralene, epoxy powder coating, transfer molding, and manual encapsulation. Transfer molding and manual potting improved the hermeticity but produced microcracking and reduced heat transfer ability following encapsulation. Additional study on manufacturing and encapsulating of the package is needed.
Date: November 1, 1996
Creator: Adams, B.E. & DeMarco, V.
Partner: UNT Libraries Government Documents Department

Residual gas analysis (RGA) and shear strength characteristics of a silver-filled epoxy and polyimide under long-term, high-temperature storage conditions. Final report

Description: Introduction of organic materials into hermetically sealed electronic packages increases the risk of failure due to contamination. The contaminants of concern are moisture and ionics. This combination can lead to unwanted electrical pathways and/or corrosion. To minimize sealed-in moisture, packages are vacuum-baked for 16 hours at 200 C and Au/Sn solder-sealed i a glove box purged with dry nitrogen. Even following this procedure, the package plating and organic adhesive can still outgas moisture during high-temperature storage. Long-term aging characteristics for a silver-filled epoxy and a silver-filled polyimide were investigated. Leadless chip carriers (LCCs) containing die attached with epoxy or polyimide were aged at 25 C, 100 C, 150 C, and 200 C for up to six months. Residual gas analysis (RGA) and die shear testing were performed on each package. Results indicate that the epoxy can withstand storage at 150 C with no increase in internal moisture. The polyimide could only be stored at 100 C. No loss in shear strength for epoxy or polyimide was noted at any storage condition.
Date: April 1, 1994
Creator: Adams, B. E.
Partner: UNT Libraries Government Documents Department