| Summary: | 碩士 === 中華大學 === 機械工程學系碩士班 === 102 === Under the demand of 3C consumer market, electronic devices are expected to be lighter, thinner, smaller with more functions and higher performance in near future. In order to match this goal, it is necessary to add-on more functions into one single chip and this makes a multi-functional chip much larger than before. It can also expect that the more function designed into a chip the more complicated manufacture method is required.
2.5 dimension assembly is one of the key solutions to solve these problems. By using a silicon interposer, it is possible to make smaller bump pitch, thinner circuits and better electronic signal performance. With an additional advantage, silicon interposer is a perfect low-k material that can prevent stress damage caused by heat. Embedding silicon interposer into a PWB carrier can decrease thickness and develop more finer bump pitch that will present higher performance and better reliability.
In this study the ANSYS is selected as the finite element model tool to investigate the thermal-mechanical behavior of the packages. Model A is the model of embedded flip chip structure. Model B is the 2.5 dimension embedded structure. We run the models on TCT simulation with -25oC to 125oC 60 minutes a loop thermo condition (as a Eighth symmetry global model). To have closer reality results, we input an equivalent layer by calculating inner circuit metal and dielectric material volume ratio. As for material characteristic: Solder ball, dielectric material and green paint are non-linear material, other materials are all linear material. The contact interface we use Contacting element technology.
According to simulation results, model A’s max displacement is 0.013353 mm and model B’s is 0.001195 mm. Model A’s max stress is 23.4564 MPa and model B’s is 18.725 MPa. Modal A’s max plastic strain is 0.054016 mm and model B’s is 0.005905 mm. Model A’s max plastic state variables is 33.9304 and Model B’s is 34.078 Model A’s max plastic density is 1.31388 J/mm2 and model B’s is 0.609504 J/mm2.
Using ANSYS to calculate Fatigue Life; Model A’s fatigue life is 4404 and model B’s is 31450.
After simulation analysis, we found that model B have smaller stress and strain than model A and model B’s fatigue life is longer than model A’s. This result proves that 2.5 dimension with embedded structure in much more advantage than traditional embedded structure.
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