Electronic packaging

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

Design Optimization and Reliability of PWB Level Electronic Package

Abstract: As the electronic packaging industry develops technologies for fabrication of smaller, faster, economical and reliable products, thermal management and design play an important role. Temperature fluctuations caused by either power consumption or environmental changes, along with the resulting thermal expansion mismatch between the various packages materials result in deformation stresses in packages/assemblies especially in solder interconnects. Increased power dissipation and density in modern electronics system requires efficient and intelligent design and thermal management strategies to ensure the reliability of electronic products. In the past reliability issues related to optimization of electronic packages were dealt with by coupling analysis tools with optimization solvers. In this paper, ANSYS APDL code is used with a built-in optimization tool for optimization of electronic packages, and for improving the solder joint life and arriving at optimal design. It has been shown that, design optimization would enormously decrease the lead time. The finite element tool ANSYS is used to estimate the cycles to fatigue failure of solder joint of the package coupled with optimization module present in the solver for providing the details on determining optimal design parameters that affect the product reliability. Four model characteristics: printed wiring board (PWB) core in-plane Young’s modulus, PWB core in-plane coefficient of thermal expansion, PWB core thickness, and the standoff solder joint height are chosen as the optimization inputs (design variables) that ensure higher reliability and improved performance of the assembled product. The objective junction of the paper is to minimize average plastic work to improve the fatigue life of solder joints of the package. Subapproximation, design of experiment and central composite design based response surface modeling methodologies are used to study the effects of each design variables on the fatigue life.

Development of Single Phase Liquid Cooling Solution for 3-D Silicon Modules

Abstract: Demand for increased functionalities and the trend in product miniaturization have created new challenges for electronic packaging. The move to 3-D packages combines the benefits of small footprint packages and through-silicon-vias technology to overcome the limitations. However, thermal management of such packages has become the bottleneck as cooling solutions cannot access the intermediate stacks within the package. A single phase liquid microchannel cooling solution had been designed in this paper to overcome such limitations. First, the thermal resistances within the package had been identified using a 1-D thermal network. The interconnect and silicon substrate (carrier) thermal resistances have been found to be of the same order of magnitude. Flip chip with conductive underfill is chosen as the interconnect scheme balancing the thermal, mechanical, and electrical requirements. Flow distribution in the microchannels and their impact on the thermal performance were also analyzed numerically. A dual inlet, dual outlet microchannel heatsink design with a supply plenum tapering downstream was found to provide the most even flow distribution for removing the heat away from the die. A thermal resistance of 0.15 °C/W and lower temperature variation on die can be obtained with such a microchannel array arrangement. Lower hydraulic losses arising from the shorter flow length and lower mean velocities also allowed the integrated pumps to operate either at smaller sizes or higher flowrates. The methodology to derive the cooling solution is presented with due consideration to the silicon fabrication processes involved.

Tri-Layer Structures Subjected to Combined Temperature and Mechanical Loadings

Abstract: Thermal stress has been a concern in electronic packaging for decades. More recently, mechanical bending of printed circuit board (PCB) assembly has attracted increased interest due to the drop impact failure of interconnects in mobile products. Analytical solutions are available in the literatures for a PCB assembly modeled as a tri-layer structure, consisting of IC components, PCBs, and an interconnect layer, subjected to either thermal stress or mechanical bending, but there are no known reports for combined loadings. This paper presents a comprehensive treatment for a PCB assembly subjected to combined temperature and mechanical loadings, taking into account the axial, shear, and flexural deformation of the interconnects. Solutions are provided for two types of interconnect layer: one in which the interconnect layer is made of a continuous element such as adhesive, and another in which the interconnect layer is made of discrete elements such as solder joints. The solutions were successfully validated with finite-element analysis, and design analyses were performed for both types of interconnect layers.

Experimental study for reliability of electronic packaging under vibration

Abstract: An automated fatigue-testing system was developed for an experimental study on the integrity of the electronic packaging subjected to mechanical vibration. The fatigue-testing machine utilized the electromagnetic device as an actuator. A data acquisition system was developed for the fatigue test of the electronic board. The fixture for the specimen was designed to be suitable for measuring the fatigue life of a typical module/lead/card electronic system subjected to vibration. With this automated fatiguetesting machine, the mechanical integrity of surface mount component with the spider gullwing leads has been studied by a mechanical flexural fatigue test. An experimental method was developed to measure the changes in electrical resistance in the lead, which is used to indicate a fatigue failure. Finally, a relationship between the loading force and the fatigue life of high-cycle region was discussed for the lead of spider gullwing type surface-mounted component. With the relation, the fatigue life of the surface-mounted component (SMC) subjected to vibration environment was predicted successfully.

Integrated Module Board (IMB); an advanced manufacturing technology for embedding active components inside organic substrate

Abstract: One of the main questions and challenges in current electronics manufacturing and packaging development is how to integrate mote functions into the same or even smaller size. The electrical performance and the number of functions of every new product generation have increased and at the same time the size has decreased. Due to this the packaging density of the products has increased quite rapidly during past years. At the same time there is a need for better electrical properties of the package and the interconnection itself. This development has caused big challenges for the used packaging and manufacturing technologies. With traditional technologies it has become more difficult to increase the packaging density. To meet these requirements Integrated Module Board (IMB) technology has been developed. In the Integrated Module Board technology active components are embedded inside a printed wiring board (PWB) or other organic substrate. The IMB process combines PWB manufacturing, component packaging and component assembly into a single manufacturing process flow. The manufacturing process allows embedding an entire product or some of its functional parts inside the substrate. All interconnections between the IC and the substrate are done simultaneously using an electroplating process. The IMB technology enables high interconnection density with good reliability. In this paper an overview of IMB technology, its technological capability and electrical performance are presented.