Thermal conductivity of rocksalt and other geologic materials from the site of the proposed waste isolation pilot plant

The measurements first reported by Acton on the thermal conductivity of samples taken from a borehole at the site of the proposed nuclear waste isolation pilot plant (WIPP) near Carlsbad, NM, have been extended to include additional samples and higher temperature measurements. Samples for measurements were taken from several depths of three wells, including the well AEC 8 from which Acton obtained his samples. These samples ranged from relatively pure rocksalt (NaCl) with small amounts of interstitial anhydrite to essentially nonsalt samples composed of gypsum or clay. The measurements in this latest series were conducted at Sandia, the Los Alamos Scientific Laboratory (LASL), and at Dynatech Corp. In general, the data from the three laboratories agreed reasonably well for similar coarse grained translucent rock salt samples, with the LASL and Sandia results typically being about 20% higher than those of Dynatceh. On the basis of these experiments, it is concluded that the thermal conductivity of materials found at the site can be predicted to an accuracy +-30% from knowledge of the composition and grain size of these materials

Stresses from flip-chip assembly and underfill; measurements with the ATC4.1 assembly test chip and analysis by finite element method

The authors report the first measurements of in-situ flip-chip assembly mechanical stresses using a CMOS piezoresistive test chip repatterned with a fine pitch full area array. A special printed circuit board substrate was designed at Sandia and fabricated by the Hadco Corp. The flip-chip solder attach (FCA) and underfill was performed by a SEMATECH member company. The measured incremental stresses produced by the underfill are reported and discussed for several underfill materials used in this experiment. A FEM of a one-quarter section of the square assembly has been developed to compare with the measured as-assembled and underfill die surface stresses. The initial model utilized linear elastic constitutive models for the Si, solder, underfill, and PC board components. Detailed comparisons between theory and experiment are presented and discussed

Calculation and Validation of Thermomechanical Stresses in Flip Chip BGA Using the ATC4.2 Test Vehicle

We report the first in situ measurements of thermomechanical stresses in a 1000 I/O 250 {micro}m pitch piezoresistive flip chip test chip assembled to a 755 I/O 1.0 mm pitch 35 mm Ball Grid Array (BGA). The BGA substrates employed build-up dielectric layers containing micro-vias over conventional fiberglass laminate cores. Experimental data, which include in situ stress and die bending measurements, were correlated to closed form and Finite Element Method (FEM) calculations. Cracking and delamination were observed in some of the experimental groups undergoing temperature cycling. Through use of bounding conditions in the FEM simulations, these failures were associated with debonding of the underfill fillet from the die edge that caused stresses to shift to weaker areas of the package

Hormone Therapy and the Risk of Breast Cancer in BRCA1 Mutation Carriers

Background: Hormone therapy (HT) is commonly given to women to alleviate the climacteric symptoms associated with menopause. There is concern that this treatment may increase the risk of breast cancer. The potential association of HT and breast cancer risk is of particular interest to women who carry a mutation in BRCA1 because they face a high lifetime risk of breast cancer and because many of these women take HT after undergoing prophylactic surgical oophorectomy at a young age. Methods: We conducted a matched case-control study of 472 postmenopausal women with a BRCA1 mutation to examine whether or not the use of HT is associated with subsequent risk of breast cancer. Breast cancer case patients and control subjects were matched with respect to age, age at menopause, and type of menopause (surgical or natural). Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated with conditional logistic regression. Statistical tests were two-sided. Results: In this group of BRCA1 mutation carriers, the adjusted OR for breast cancer associated with ever use of HT compared with never use was 0.58 (95% CI = 0.35 to 0.96; P =. 03). In analyses by type of HT, an inverse association with breast cancer risk was observed with use of estrogen only (OR = 0.51, 95% CI = 0.27 to 0.98; P =. 04); the association with use of estrogen plus progesterone was not statistically significant (OR = 0.66, 95% CI = 0.34 to 1.27; P =. 21). Conclusion: Among postmenopausal women with a BRCA1 mutation, HT use was not associated with increased risk of breast cancer; indeed, in this population, it was associated with a decreased risk

Mouse Chromosome 11

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46996/1/335_2004_Article_BF00648429.pd

Accelerated lifetesting of thin film tungsten contacts for a milliwatt Si-- Ge thermopile

In this report, experimental results are presented for similar accelerated lifetests conducted in the temperature range of 550-725 degree Celsius with current design single row per channel or "one dimensional" thermophiles

Pressure effects on thermal conductivity and expansion of geologic materials

Through analysis of existing data, an estimate is made of the effect of pressure or depth on the thermal conductivity and expansion of geologic materials which could be present in radioactive waste repositories. In the case of homogeneous dense materials, only small shifts are predicted to occur at depths less than or equal to 3 km, and these shifts will be insignificant as compared with those caused by temperature variations. As the porosity of the medium increases, the variation of conductivity and expansion with pressure becomes greater, with conductivity increasing and expansion decreasing as pressure increases. The pressure dependence of expansion can be found from data on the temperature variation of the isobaric compressibility. In a worst case estimate, a decrease in expansion of approx. 25% is predicted for 5% porous sandstone at a depth of 3 km. The thermal conductivity of a medium with gaseous inclusions increases as the porosity decreases, with the magnitude of the increase being dependent on the details of the porosity collapse. Based on analysis of existing data on tuff and sandstone, a weighted geometric mean formula is recommended for use in calculating the conductivity of porous rock. As a result of this study, it is recommended that measurement of rock porosity versus depth receive increased attention in exploration studies and that the effect of porosity on thermal conductivity and expansion should be examined in more detail

Effect of experimental variables on flash thermal diffusivity data analysis

Flash thermal diffusivity data are usually analyzed with a thermal model which assumes axial heat conduction and uniform illumination of the flashed surface. For high accuracy data reduction, it becomes important to bound to the errors caused by radial heat flow and by non-uniform laser beam profiles. These effects are examined analytically for a case in which the incident laser beam is confined to a radius smaller than the sample radius. The dependence of the output of an averaging detector on the magnitude of the radial heat transfer coefficient is presented and the linear dependence of radial and axial loss sensitivity coefficients is discussed. From this discussion, we conclude that inclusion of radial loss effects in analysis of the thermal response of multilayer structures is not important unless the radial loss factor is very large. Analytical results are presetned for the temperature vs. time response of a two layer composite sample with interfacial thermal resistance and high thermal losses at the sample faces. The use of these results to reduce data for two multilayer samples is presented to show the utility of new data reduction techniques