Electromigration statistics and damage evolution for Pb-free solder joints with Cu and Ni UBM in plastic flip-chip packages

A series of electromigration (EM) tests were performed as a function of temperature and current density to investigate lifetime statistics and damage evolution for Pb-free solder joints with Cu and Ni under-bump-metallizations (UBMs). The EM lifetime was found to depend on the failure criterion used, so the results were compared based on the first resistance jump and conventional open-failure criterion. Solder joints with Cu UBM had a longer lifetime than Ni UBM based on the open-failure criterion, but the lifetime with Ni UBM became comparable when the first resistance jump criterion was applied. To determine the temperature in solder joints, the Joule heating effect was investigated with experiments and finite element analysis. The temperature of solder joints was determined to be approximately 15°C higher than that at the Si die surface when 1 A of current was applied. With the appropriate temperature correction, the activation energies and the current density exponents were found to be Q = 1.11 eV, n = 3.75 and Q = 0.86 eV, n = 2.1 based on the open-failure criterion for solder joints with Cu and Ni UBM, respectively. Based on the first resistance jump criterion, Q = 1.05 eV, n = 1.45 for Cu UBM and Q = 0.94 eV, n = 2.2 for Ni UBM, respectively. For solder joints with Cu UBM, voids were formed initially at the Cu₆Sn₅/solder interface while the final open failure occurred at the Cu₃Sn/Cu₆Sn₅ interface. For Ni UBM, voids were formed initially at the Ni₃Sn₄/solder interface leading to failure at the same interface. The formation of intermetallic compounds (IMCs) was enhanced under current stressing, which followed linear growth kinetics with time. The IMC growth was accompanied by volume shrinkage, which accelerated damage evolution under EM.     

Droloxifene does not blunt bone anabolic effects of prostaglandin E2, but maintains prostaglandin E2-restored bone in aged, ovariectomized rats

The authors examined 1) effects of nortriptyline (NT) on electroencephalographic (EEG) sleep measures in elderly patients with bereavement-related depression in remission under randomized, double-blind, placebo-controlled conditions, and 2) the effects of clinical remission on sleep after discontinuation of medication. Subjects were classified as responders to placebo (n = 9) or NT (n = 18) and had EEG sleep studies at three time-points: before treatment (T1), remitted on medication or placebo (T2), and remitted off medication or placebo (T3). As compared with placebo, NT was differentially associated with decreases in REM sleep time and percent and increases in REM sleep density (T2). No changes in EEG sleep measures occurred in placebo responders. REM sleep measures in NT responders reverted to T1 levels after T3, with persistence of robust clinical remission and normal subjective sleep quality. These data suggest that NT alters REM sleep, but that EEG sleep characteristics in bereavement-related depression persist into remission.     

Randomized clinical trial of a new dexamethasone delivery system (Surodex) for treatment of post-cataract surgery inflammation

OBJECTIVE: To evaluate the safety of Surodex Drug Delivery System (Oculex Pharmaceuticals, Inc., Sunnyvale, CA) containing dexamethasone 60 micrograms, for use in cataract surgery, and to compare its anti-inflammatory efficacy with conventional dexamethasone 0.1% eyedrops. DESIGN: Randomized, masked, and partially controlled trial. PARTICIPANTS: Sixty eyes of 60 Asian patients undergoing extracapsular cataract extraction with intraocular lens implantation were examined. Of these, 28 eyes of 28 patients served as control eyes. Patients were stratified for age and presence of diabetes mellitus. INTERVENTION: Surodex was inserted in the anterior chamber of 32 eyes at the conclusion of surgery. These eyes received placebo eyedrops four times a day after surgery for 4 weeks. Control eyes received neither Surodex nor a placebo implant but were prescribed conventional 0.1% dexamethasone eyedrops four times a day for 4 weeks. MAIN OUTCOME MEASURES: Anterior chamber cells and flare were clinically graded at the slit lamp. Anterior chamber flare was objectively assessed with the Kowa FM500 Laser Flare Meter (Kowa Co. Ltd, Tokyo, Japan) for up to 3 months after surgery. Intraocular pressure and corneal endothelial specular microscopy with morphometric cell analysis were performed for up to 1 year after surgery. RESULTS: Clinical slit-lamp assessment of anterior chamber flare and cells showed no difference between Surodex-treated eyes and dexamethasone eyedrop-treated eyes. Flare meter readings showed lower flare levels in the Surodex group at all postoperative visits compared with the dexamethasone eyedrop group. Flare reduction in the Surodex group reached statistical significance at days 4, 8, 15, and 30 after surgery. At 3 months, flare was reduced to preoperative levels in the Surodex group but was still raised in the dexamethasone eyedrop group. Five eyes in the dexamethasone eyedrop group required augmentation of steroids and were deemed therapeutic failures as opposed to one eye in the Surodex group. One patient in the dexamethasone eyedrop group developed postoperative open-angle glaucoma with profound visual field loss and optic disc cupping, resulting in hand movements vision. No significant difference in endothelial cell loss was noted between Surodex-inserted eyes and dexamethasone eyedrop-treated eyes for up to 1 year after surgery. CONCLUSIONS: Intraocular placement of a single Surodex is a safe and effective treatment method to reduce intraocular inflammation after cataract surgery. There was no statistical difference in efficacy between Surodex and 0.1% dexamethasone eyedrops in reducing intraocular inflammation, as measured by clinical methods, while Surodex was clearly superior to eyedrops in reducing aqueous flare as objectively assessed with the laser flare meter.