Many nonconductive inks have CTE and TG values that more closely match the board material.
As recently as 2000, filling a via was considered a specialty process limited to a small group of product applications and almost exclusively to one material: conductive ink. Furthermore, this process was dominated by one primary filling material, DuPont CB100. The through-hole vias were filled so that a copper cap could be plated over the via surface to create a solderable land on top of the via, and thus “via-in-pad.”
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