This paper will present the research results for reliability of two embedding technologies in comparison to the current standard - surface mount technology. The chosen embedding approaches utilize a cavity to place the necessary components into the PCB core. The difference is found in the way the component is connected to the PCB routing. For the first approach the circuit is first assembled on a carrier substrate using conventional surface mount technology (SMT). The solder paste is printed, the components are placed and the substrate board is soldered afterwards. The base substrate is then put together with prepared additional layers holding preformed cavities at the component locations. After another top layer has been added, the stack is finally laminated and the components are placed in the PCB core. The second approach is based on placing the components, then putting together the stack-up as described earlier and followed also with the laminating process. However the components have not been soldered. Instead an opening to the component's terminals is created through laservias. Then galvanic deposition is utilized to establish the connection to the PCB routing. For a comparison of the technologies samples with embedded resistors and ceramic capacitors in various sizes for the technologies as well as standard SMT have been prepared. To assess the reliability potential the samples have undergone temperature cycling tests. The testing is supported with FEM simulations which aided in the detection of critical design parameters and assess the residual manufacturing stress/strain states. The results of the investigations have shown that the damage mechanisms and predominant failure sites of the SMT & Cavity embedding variant is significantly different from conventional SMT. Here the resin material should be adopted to increase lifetimes even more. In the case of Microvia & Cavity the geometry of the microvia is essential towards the achievable reliability. Overall the results indicate the increased reliability potential of the novel approaches
The market increasingly demands remote monitoring sensors and electronics for safety-related industrial equipment, transport vehicles and also building structures. In these applications the robustness of the electronics and the reliability of the packaging technology are key factors. Reliability requirements are for electronic modules are derived from environmental and operational loads. This leads to general requirements for the system concept to ensure their operation and thus system reliability. Most frequently the focus is set on thermomechanical design issues. The presented work however includes, the interpretation under a different loading scenarios - long-term use under constant media exposure in a maritime environment in seawater. The application scenario is monitoring of the foundation structure for offshore wind turbines. Specific requirements to protect the sensors and sensor electronics from the surrounding medium seawater and permanent pressure load of 3 to 6 bar in the application of water depth between 20 to 50 meters. Other environmental conditions are occurring minerals and microorganisms which can attack the package system in the long term. The permanent installation of electronics requires a system design with lifetimes in the range of the test structure itself, which is set to 10 years. The presented work includes extensive characterizations of organic potting compounds for this purpose. Emphasis has been put into the materials resistanzes to media and diffusion properties. Furthermore, aging effects and their impact will be presented on mechanical stability of the polymer systems. These include displacements of the characteristic glass transition and the variation of the elastic modulus. The results include relevant material classes and circuit board materials. As potential life-reducing mechanisms unwanted material changes through media storage and path formation within the polymer system have been identified
The presented work deals with the reliability issues of embedded components in a PCB core. The process of the embedding technology is discussed in the course of this paper. We showed that the selection of manufacturing parameters strongly influences the quality of the embedding process and therefore the reliability of embedded systems. Results of the researches carried out at different values of decisive parameters are presented. We fabricated prototypes with embedded resistors and capacitors using the technology described in the article and tested them for their reliability. Additionally the effect of temperature and pressure during the manufacturing process on the electrical parameters of embedded components has been studied. As a result, we compared the reliability of PCBs produced by the embedding and the surface-mount technology and evaluated the impact of manufacturing faults on reliability
This work presents the research towards two promising embedding approaches for electronic components with a possible application to integrate a sensor node for structural health monitoring into the structure itself. The production process for both integration methods has been assessed through experimental and simulation effort. Samples with passive components for both presented approaches have been successfully built. To evaluate the quality of the integration processes, the embedding samples along with regular SMT assemblies were subsequently tested towards reliability using tensile and temperature cycling tests with in-situ measurement. Both testing methods have also been supported with advanced finite element modeling to understand the structural behavior for the integration. The results have shown that both approaches can successfully be applied to integrate electronics into organic material. It was also found that the damage mechanism during the thermo mechanical loading for embedded components differs from conventional SMT assembly because the solder is completely fixated. With a correct manufacturing process this will yield an increase of life time for the electronics
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