John Burkhert

Or why aspect ratio rules all.

The humble via comes in many flavors. By connecting one layer of a conductor pattern to another, vias have connected the world. My career has depended on them as part of the hardware I used to design for others to use. A foundational innovation in electronics brought plated through-holes to the masses. As a leap forward from wire-wrap technology, multilayer printed circuit boards put a “mainframe” in each of our pockets almost overnight.

From the first plated through-hole to the latest, the trend is to support higher-density interconnect. The key driver in plating holes is the aspect ratio, the hole’s width relative to its depth. For a through-hole, the depth is the thickness of the PCB. Most reputable fabricators can handle a 10:1 ratio, such that a common 0.062" board thickness will require a minimum finished hole size 0.006" (FIGURE 1).

To continue reading, please log in or register using the link in the upper right corner of the page.

Submit to FacebookSubmit to Google PlusSubmit to TwitterSubmit to LinkedInPrint Article