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As the aerospace industry has been tasked with fitting increasingly complex electronics in existing airframes the demands on PCB substrates have begun to overtask the existing state of the art in PCB fabrication.
Recently, I was called in to troubleshoot some reliability problems with a very dense PCB that had components on both sides and required the use of stacked blind vias and buried vias. The usual name for this kind of design is “build-up fabrication,” requiring many trips through the lamination, drilling, and plating operations at a fabricator.
The designers decided to reach down from the outer layer to the third layer below the surface using stacked blind vias.
The process used to create the structure in Figure 1 is to fabricate a PCB using the ordinary lamination, drilling, and plating processes employed for any multilayer PCB. Once this is done, a laser drill is used to create the first blind via at the bottom of the stack as shown in Figure 1.
To read this entire article, which appeared in the January 2023 issue of Design007 Magazine, click here.
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