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Force-System Resultants and Equilibrium
Published in Richard C. Dorf, The Engineering Handbook, 2018
Figure 11.125 Example of PCB and microvia construction. to the length of the hole. A microvia is defined as a conductive hole that has an aspect ratio of 1:1, which means that a microvia only connects two adjacent conductive layers of the PCB, and the diameter of the hole is equal to the thickness of the one board layer (6,16-19).
Polymers
Published in Andrea Chen, Randy Hsiao-Yu Lo, Semiconductor Packaging, 2016
Andrea Chen, Randy Hsiao-Yu Lo
To allow substrates to shrink further for chip-scale packages used in portable devices—like mobile handsets—microvia technology was employed. Microvia interconnects are formed using blind or buried vias, which often connect the outer layer with the layer directly underneath, thus saving real estate, because they do not extend through the entire board. An example is shown in Figure 6.26 of a 2-2-2 build-up substrate—two layers each of buildup on top and bottom with a conventional two-layer PCB board as the core.
Study of microvia filling process based on multi-physical coupling
Published in Transactions of the IMF, 2018
Linxian Ji, Hexian Nie, Shidong Su, Yuanming Chen, Wei He, Kehua Ai
Generally, copper deposition at the opening of a microvia is faster than that at the bottom of the microvia under the condition of primary current distribution, which causes a pinch-off effect to form a void inside the microvia. To achieve a void-free filling of a microvia, the superfilling method was proposed,6 which resulted in a completely filled via while the deposit thickness outside the microvia was kept small. Recently, many efforts have been made to realise the superfilling of microvias. One was to update the configuration of the plating bath and facilities, such as using an insulating shield, auxiliary electrode and jet pipe.7 The other was to use pulse current waveform, which could generate a periodic relaxation time to effectively enhance mass transfer of cupric ions.8 In addition, additive-assisted copper electrodeposition could also lead to a synergetic effect to form a perfect copper deposition, which has been widely studied.9–11