Electronic packaging

About: Electronic packaging is a research topic. Over the lifetime, 3977 publications have been published within this topic receiving 48510 citations.

Reliable packaging technologies for power electronics: Diffusion soldering and heavy copper wire bonding

Abstract: Production of a reliable power module capable of achieving higher switching frequencies and higher junction temperatures is limited by the present assembly and packaging methods, mostly in the areas of the die-attach and the top level interconnections. The present study aims to display the advances in packaging technologies of diffusion soldering and heavy copper wire bonding in the view of material characterization, process optimization and quality improvement. In diffusion soldering, the growth of intermetallic phases through thin-layer paste deposition and solder profile optimization with vapor phase soldering were investigated. Solder paste inspections were performed to evaluate the errors during deposition process for thin layers and influences on soldering process and related post-failure modes. In heavy wire copper bonding, the impact of substrates with a mechanically polished surface of reduced roughness was investigated. Furthermore the influence of applying the bond force in a ramp style was examined and inspected with the pull and shear forces. The bond width was also monitored in order to receive a non-destructive quality feature for the process monitoring. All test series were accompanied by a close control of the tool wear-out and its influence on process stability.

New fabrication technology of polymer/metal lamination and its application in electronic packaging

Abstract: A new fabrication technology for lamination between LCP (liquid crystalline polymer)and copper is presented. The method is based on a surface activation process prior to the clad bonding process. The fabrication conditions and the microstructure of the bonded interface as well as the mechanism of the bonding are discussed with respect to various experimental results. Some practical applications of the new clad materials in electronic packaging are also presented.

High frequency electrical characterization of electronic packaging materials: environmental and process considerations

Abstract: Recognizing the need for improved materials data to meet the needs of designers of RF and microwave products, DuPont Photopolymers and Electronic Materials (P&EM) has had an ongoing program to generate high frequency data on materials properties (dielectric constant, loss tangent and attenuation). Characterization of ceramic and printed wiring advanced interconnection materials in the 1 to 20 GHz range has been performed for a variety of new Thick Film and Low Temperature Cofired Ceramic (LTCC) dielectrics. Gold and silver conductors applied by both screen printing and photopatterning on these dielectrics as well as on 96% alumina have been tested. These have been benchmarked against Thin Film conductors and copper clad FR-4, Polyimide, BT and Teflon/sup (R)/ printed wiring materials. The performance of many of these systems has been reported for room temperature and humidity conditions. This presentation builds on the previous work with data on the high frequency properties of some of the advanced ceramic and printed wiring materials systems when exposed to 85/spl deg/C temperature and 85% relative humidity. In addition the high frequency performance of a new gold conductor system with both screen printed and photoetched patterning on 96% and 99% Alumina is described demonstrating the improved performance over gold Thin Film metallization typically used in Microwave applications.

Electronic packaging for optical emitters and sensors

Abstract: A VCSEL die is packaged so that its optical axis is at a predetermined non-perpendicular and nonparallel angle relative to the plane of a PCB to which the packaged die will be mounted. The die is packaged to form an emitting component which is shaped to orient the VCSEL optical axis at the predetermined angle when the component is placed onto a PCB. The component can be used in combination with a flip-chip sensor IC located on an opposite side of a PCB from the emitting component. The component can also be used in combination with a CSP sensor IC on the same side of a PCB. A VCSEL die and sensor IC can be contained in a single package. The optical axis of the VCSEL die packaged with a sensor IC may or may not be perpendicular to a plane of an array in the sensor IC.

A Novel Anisotropic Conductive Adhesive for Lead-Free Surface Mount Electronics Packaging

Abstract: The electronics industry, in recent years, has been focusing primarily on product miniaturization and lead-free assembly. The need for product miniaturization is due to the continuous demand for portable electronic products that are multifunctional, yet smaller, faster, cheaper, and lighter. This is forcing the industry to design and assemble products with miniature passive and active devices. These devices typically have fine pitch footprints that provide a very small surface area for attachment. The solder attach technique relies primarily on the formation of intermetallics between the mating metallic surfaces. With a reduction in the surface area of the pads, the ratio of intennetallic to solder is very high once the solder joint is formed. This could result in unreliable solder joints, due to the brittle nature of intermetallics. In addition, the need to eliminate lead-based materials as a means of interconnection has renewed the industry's interest in exploring other means of assembling surface mount devices reliably. The use of a novel anisotropic conductive adhesive (ACA) as a means for assembling surface mount devices, the ACA's performance characteristics, and preliminary research findings are discussed in this paper. Typically, ACAs require the application of pressure during the curing process to establish the electrical connection. The novel ACA uses a magnetic field to align the particles in the Z-axis direction and eliminates the need for pressure during curing. The formation of conductive columns within the polymer matrix provides a very high insulation resistance between adjacent conductors. The novel ACA also enables mass curing of the adhesive, eliminating the need for sequential assembly. The novel ACA was found to be very effective in providing the interconnection for surface mount technology (SMT) passives and leaded, bumped, or bumpless integrated circuit packages. The requirement for precise stencil printing was eliminated, as the application of magnetic field aligned the conductive columns in the Z-axis direction eliminating any lateral conductivity. The ability to mass cure the adhesive while applying the magnetic field reduced the assembly time considerably. Placement accuracy was still found to be very critical. Shear testing of adhesive joints after thermal aging showed significance past 500 h and after temperature-humidity aging showed significance within the first 100 h. 1-V characteristics of the daisy chained ball grid array devices assembled with and without bumps revealed considerable difference in the breakdown current. The correlation between initial contact resistance of the daisy chain and the final breakdown current was also determined. Preliminary experiments and findings, discussed in this paper, show the viability of the ACA for mixed SMT assembly. Further experimentations will include in situ contact resistance measurements during thermal aging, temperature-humidity aging, drop testing and thermal shock.