{"id":41,"date":"2020-06-25T07:46:39","date_gmt":"2020-06-25T11:46:39","guid":{"rendered":"https:\/\/blogs.sw.siemens.com\/pcbflow\/?p=41"},"modified":"2026-03-27T09:45:48","modified_gmt":"2026-03-27T13:45:48","slug":"pcb-aspect-ratio-how-do-you-know-your-board-is-manufacturable","status":"publish","type":"post","link":"https:\/\/blogs.sw.siemens.com\/electronic-systems-design\/2020\/06\/25\/pcb-aspect-ratio-how-do-you-know-your-board-is-manufacturable\/","title":{"rendered":"PCB Aspect Ratio \u2013 how do you know your board is manufacturable?"},"content":{"rendered":"\n

A majority of PCB fabricators proudly publish their aspect ratio production capability. Some even go further and publish their maximum aspect ratio per hole type<\/em>, which is especially important for high density interconnect (HDI) boards. But how can you be sure that your design meets your manufacturer\u2019s PCB aspect ratio capability?<\/p>\n\n\n\n

What is PCB Aspect Ratio and why is it important?<\/h2>\n\n\n\n

Aspect Ratio is the ratio of the hole\u2019s diameter to the thickness of the material it is piercing through, as shown in figure 1:<\/p>\n\n\n

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Figure 1: Aspect ratio<\/p>\n\n\n\n

Aspect ratio is particularly critical for ensuring a consistent plating process: the smaller the aspect ratio is, the higher the probability of consistent copper plating throughout the length of the hole. Aspect ratios that are higher than the maximum supported by a fabricator may result in insufficient plating of the hole, which, in turn, will result in a broken net in the case of a via hole, or in assembly failure in case of a component plated through-hole.  <\/p>\n\n\n\n

Fabricators usually publish a set of maximum manufacturable aspect ratios for multiple processes, such as through holes and microvias.  And of course, each fabricator may publish a different set.  With all this uncertainty, it is very important to verify that your design is suitable to your manufacturer\u2019s capabilities in general \u2013 and to their aspect ratio in particular.<\/p>\n\n\n\n

So how do you verify it?<\/h2>\n\n\n\n

Usually, the aspect ratio is checked by the manufacturer as part of the DFM process. But here\u2019s the challenge \u2013 both the designer and the manufacturer are missing crucial information:<\/p>\n\n\n\n