Technical Library | 2019-07-10 23:36:14.0
Pockets of gas, or voids, trapped in the solder interface between discrete power management devices and circuit assemblies are, unfortunately, excellent insulators, or barriers to thermal conductivity. This resistance to heat flow reduces the electrical efficiency of these devices, reducing battery life and expected functional life time of electronic assemblies. There is also a corresponding increase in current density (as the area for current conduction is reduced) that generates additional heat, further leading to performance degradation.
Technical Library | 2022-01-26 15:26:56.0
In this work an attempt is made to improve the fracture toughness and electrical conductivity of epoxy/glass fiber based laminates by the inclusion of carbon nanotube (CNT) fillers. The fiber orientation of the epoxy/ glass fiber (GF) fabric laminates was optimized based on estimation of mechanical properties. The carboxylic acid functionalized CNTs were incorporated into epoxy matrix by ultra-sonication method. The nano filled epoxy resin was used to prepare laminates with 30/45 GF fabric orientation. The CNT content was varied and its effect on the tensile properties was determined. The fracture toughness of multiphase composites was estimated using single edge notch bend (SENB) test. The presence of CNTs improved the fracture toughness by a crack bridging mechanism. The volume resistivity of multiphase composites was found to be superior to the conventional epoxy/CNT composite. The presence of glass fabric reduces the number of inter-tube contacts contributing to the reduction in volume resistivity.
Technical Library | 2013-01-18 02:42:14.0
ENIG (Electroless Nickel/Immersion Gold) is to deposit nickel gold plating which has good solderability, wear resistance , leveling appearance and small electric resistance. It included 4 steps that are pretreatment, immersion nickel, immersion gold and Post treatment...
Technical Library | 2017-03-09 17:37:05.0
This article focuses on the fabrication and characterization of stretchable interconnects for wearable electronics applications. Interconnects were screen-printed with a stretchable silver-polymer composite ink on 50-μm thick thermoplastic polyurethane. The initial sheet resistances of the manufactured interconnects were an average of 36.2 mΩ/◽, and half the manufactured samples withstood single strains of up to 74%. The strain proportionality of resistance is discussed, and a regression model is introduced. Cycling strain increased resistance. However, the resistances here were almost fully reversible, and this recovery was time-dependent. Normalized resistances to 10%, 15%, and 20% cyclic strains stabilized at 1.3, 1.4, and 1.7. We also tested the validity of our model for radio-frequency applications through characterization of a stretchable radio-frequency identification tag.
Technical Library | 2009-10-08 01:58:04.0
In the present study, we report novel ferroelectric-epoxy based polymer nanocomposites that have the potential to surpass conventional composites to produce thin film capacitors over large surface areas, having high capacitance density and low loss. Specifically, novel crack resistant and easy to handle Resin Coated Copper Capacitive (RC3) nanocomposites capable of providing bulk decoupling capacitance for a conventional power-power core, or for a three layer Voltage-Ground-Voltage type power core, is described.
Technical Library | 2013-03-28 16:18:22.0
For the last couple of years, the main concerns regarding the electrical performance of blank PCB boards were impedance and ohmic resistance. Just recently, the need to reduce insertion loss came up in discussions with blank board customers (...) The paper describes the test vehicle and the testing methodology and discusses in detail the electrical performance characteristics. The influence of the independent variables on the performance characteristics is presented. Finally the thermal reliability of the boards built applying different copper foils and oxide replacements was investigated.
Technical Library | 2014-05-29 13:48:14.0
Electronics packaging based on stress-engineered spring interconnects has the potential to enable integrated IC testing, fine pitch, and compliance not readily available with other technologies. We describe new spring contacts which simultaneously achieve low resistance ( 30 μm) in dense 2-D arrays (180 ~ 180-µm pitch). Mechanical characterization shows that individual springs operate at approximately 150-µN force. Electrical measurements and simulations imply that the interface contact resistance contribution to a single contact resistance is This paper suggests that integrated testing and packaging can be performed with the springs, enabling new capabilities for markets such as multichip modules.
Technical Library | 2007-06-13 13:44:10.0
Very high performance computer applications have created a demand for large organic substrates capable of interconnecting one or a few ASIC semiconductor devices with packaged memory devices. The electrical advantages offered by the use of a thin PTFE composite substrate were coupled with intrinsic mechanical advantages to create very high performance applications. The application development required interactions of design, fabrication, and new manufacturing technology to obtain rapid prototype production and allow a successful ensuing manufacturing ramp.
Technical Library | 2023-03-13 19:27:13.0
10%) and mean strains (>30%). A trace width effect is found for the fatigue behavior of 1 mm vs 2 mm wide specimens. The input specimen-characteristic curves are trace-width dependent, and the model predicts a decrease in Nf by a factor of up to 2 for the narrower trace width, in agreement with the experimental results. Two different methods are investigated to generate the rate of normalized resistance increase curves: uninterrupted fatigue tests (requiring ∼6–7 cyclic tests), and a single interrupted cyclic test (requiring only one specimen tested at progressively higher strain amplitude values). The results suggest that the initial decrease in normalized resistance rate only occurs for specimens with no prior loading. The minimum-rate curve is therefore recommended for more accurate fatigue estimates.
Technical Library | 2023-02-13 19:14:03.0
Technology Focus: Develop and evaluate nanoparticle filled conformal coatings designed to provide long term whisker penetration resistance and coverage on tin rich metal surfaces prone to whisker growth in commercial lead-free electronics used in modern DoD systems. Research Objectives: Identify the fundamental mechanisms by which conformal coatings provide long-term tin whisker penetration resistance and inhibit nucleation/growth. Correlate mechanical properties and coverage thickness to whisker penetration resistance. Project Progress and Results: Functionalized nanosilica and non-functional nanoalumina enhanced polyurethane conformal coatings have shown improved spray coating coverage characteristics and crack resistance during thermal cycling fatigue testing. Lead-free assembly whisker mitigation validation testing is in process. Technology Transition: Current project partners provide coating materials to industry. SERDP test data will be considered during updates to the DoD adopted IPC standards for coating materials and coverage.
