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With the challenges of moving to 2.5/3D packaging structures, it has become imperative to improve our understanding of the materials science of fine pitch Pb-free solder joints. The use of Cu pillars capped with thin layers of SnAg solder provides for tighter bump pitches reducing the chance of solder bridging at chip joining. However, changes in geometry, materials and processes associated with 2...
The paper deals with the problem of thermal aging of PET and Glass-fibre based composites. These electro-insulating materials are used in high voltage engineering as parts of insulation systems of large rotating machines like turbo or hydro generators. These materials were subjected to accelerated thermal aging to provide more information about the aging effects and allow us to estimate the lifetime...
Isotropic electrically conductive adhesive with epoxy matrix filled with silver flakes was modified with addition of multi-walled silver nanotubes and with silver nanoparticles. Samples of adhesive as received and modified adhesive were formed. Part of the samples was aged in increased temperature, in increased humidity and in elevated temperature combined with humidity. Glass transition temperature...
There is difficult to imagine modern manufacturing of electrical devices without components containing (mainly for technological reasons) organic substances. This fact is mainly concerned to composite materials, in which the bond component is made of organic substance. Most of the electro-insulating materials used in common applications are composite materials. The possibility of the determination...
It is known that glassy state is a non-equilibrium state. Due to the energy excess, resulting from kinetic conditions during cooling from the liquid state, all glasses and especially polymers sustain a phenomenon called physical ageing or structural relaxation under the glass transition temperature. This phenomenon results in decrease with time of physical properties due to rearrangements of macromolecules...
The mechanical properties of polymer encapsulating materials change considerably when packages are exposed to elevated temperatures for longer times. Here we report a systematic study on the change in viscoelastic properties of a commercial molding compound which is stored at 175°C for periods of time ranging up to 4 weeks. It is shown that instead of the expected degradation, the modulus and the...
An electronic device cannot perform its designed functions until it is packaged such that it is interconnected with the rest of the system and protected. As an encapsulation material, thermosetting polymers are widely used. It is well known that properties of polymer-based composites like molding compounds are highly affected by the influence of temperature, relative humidity and degree of conversion...
In this paper we have investigated the accelerated ageing of seven different thin-film module types through the use of sequential damp heat (85??C/85% RH) tests. The module types [a-Si, tandem a-Si/a-Si micro-morph a-Si/??-Si, triple junction a-Si, CIS (x2) and CdTe] were selected to cover a range of thin-film devices, materials and construction types. Sequential damp heat tests for cumulative exposure...
Dielectric spectroscopy measurements below 1 Hz are often dominated by ldquoconduction-likerdquo effects. For this reason, they often appear to be dismissed as being of little interest. In this paper two ldquosub-hertzrdquo responses are considered that give insights into the insulating systems concerned. The first system is that of cross-linked polyethylene, taken from a power cable system. Measurements...
The electrical characterization of fine-pitch compliant Au bumps is investigated in this study. Compliant Au bumps of 20 microns pitch were fabricated on a glass substrate for chip-on-glass application. Kelvin probes are fabricated and employed to measure the bump resistance. The resistance ranges from 1.0 to 4.5 ohms, depending on process parameters. Current-carrying capability for these bumps is...
The stator windings of large air-cooled rotating machines are insulated with mica-glass fabric impregnated with epoxy. These composites are submitted to thermal, mechanical and electrical stresses. A specific aging arrangement has been setup allowing artificial thermo-oxidative aging of dielectric samples thanks to the application of a dry O2 pressure at a controlled temperature. Two different materials...
Silicone resins are used as dipping, varnishes and coatings for glass cloth and glass covered magnet wire, primarily in applications in which high ambient or operating temperatures obtain. The silicone resins often must be depended upon to maintain electrical and mechanical properties required in the specific application for long periods at temperatures as high as 180°C or even higher. The physical...
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