Lead-free interconnection for electronic devices

An electronic device that is equipped with a plurality of bonding pads positioned on the device for making electrical interconnections and electrically conductive composite bumps adhered to the bonding pads wherein the bumps are formed of a composite material consisting of a thermoplastic polymer and at least about 30 volume percent of conductive metal particles based on the total volume of the metal particles and the thermoplastic polymer. The present invention is also directed to a method of making electrical interconnections to an electronic device by pressing a plurality of composite bumps of a polymeric based material against a substrate having an electrically conductive surface by mechanical means under a sufficient temperature and/or a sufficient pressure. The present invention is further directed to a method of debonding an electronic device bonded by a composite binder by first providing an electronic device that is bonded by composite bumps consists of a thermoplastic polymer and at least about 30 volume percent of conductive metal particles and then exposing the composite bumps to a solvent or to a temperature not less than about 50% .degree. C. below the glass transition temperature of the composite bump

Plasticized, antiplasticized and crystalline conducting polymers

Materials containing precursors to electrically conductive polymers and electrically conductive polymers are described which have a high degree of crystallinity. The high degree of crystallinity is achieved by preparing the materials under conditions which provide a high degree of mobility to the polymer molecules permitting them to associate with one another to form a crystalline state. High levels of electrical conductivity are achieved in in the electrically conductive materials without stretch orienting the material. The enhanced electrical conductivity is isotropic as compared to a stretch oriented film which has isotropic electrical conductivity

High-Resolution Thin-Film Device to Sense Texture by Touch

Touch (or tactile) sensors are gaining renewed interest as the level of sophistication in the application of minimum invasive surgery and humanoid robots increases. The spatial resolution of current large-area (greater than 1 cm2) tactile sensor lags by more than an order of magnitude compared with the human finger. By using metal and semi conducting nanoparticles, a 100-nm-thick, large-area thin-film device is self-assembled such that the change in current density through the film and the electroluminescent light intensity are linearly proportional to the local stress. A stress image is obtained by pressing a copper grid and a United States 1-cent coin on the device and focusing the resulting electroluminescent light directly on the charge-coupled device. Both the lateral and height resolution of texture are comparable to the human finger at similar stress levels of 10 kilopascals

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Tactile Imaging of an Imbedded Palpable Structure for Breast Cancer Screening

Apart from texture, the human finger can sense palpation. The detection of an imbedded structure is a fine balance between the relative stiffness of the matrix, the object, and the device. If the device is too soft, its high responsiveness will limit the depth to which the imbedded structure can be detected. The sensation of palpation is an effective procedure for a physician to examine irregularities. In a clinical breast examination (CBE), by pressing over 1 cm2 area, at a contact pressure in the 70−90 kPa range, the physician feels cancerous lumps that are 8- to 18-fold stiffer than surrounding tissue. Early detection of a lump in the 5−10 mm range leads to an excellent prognosis. We describe a thin-film tactile device that emulates human touch to quantify CBE by imaging the size and shape of 5−10 mm objects at 20 mm depth in a breast model using ~80 kPa pressure. The linear response of the device allows quantification where the greyscale corresponds to the relative local stiffness. The (background) signal fro

Solid-Like Dynamics in Ultrathin Films of Polymeric Liquids

In this letter, we demonstrate that, at mesoscales, nonferroelectric liquid films of polydimethyl siloxane. exhibit significant electrostriction not present in the corresponding bulk state. Remarkably, the observed electrostrictive effect has a response time ,20 ms in contrast to .5 ms recorded in conventional bulk ~ferroelectric polymers. The emergence of this fast electrostrictive strain in thin films is explained in terms of the amalgamation of two contrasting dynamic features—the influence of a highly mobile, viscous layer ~at the air/film interface. on the less-mobile, but fast responding, solid-like layer at the film/substrate interface. The effect is observed for thickness below 200 nm

Highly Selective, Electrically Conductive Monolayer of Nanoparticles on Live Bacteria

Using specific peptide−bacteria affinity, a monolayer of 30 nm Au particle is selectively deposited on live bacteria surface to produce electrically conducting bridges spanning over 12 μm. The conductivity of the monolayer network is further improved by over 10-fold by “electric-field annealing”. The annealing process is explained by a percolation model