Backdrilling is one of the most effective manufacturing techniques for improving signal integrity in high-speed backplanes\u2014but it\u2019s also frequently misunderstood. Some teams request backdrill on every via \u201cjust in case,\u201d which can increase cost and risk without real benefit. Others skip it entirely and later struggle with resonances caused by via stubs.<\/p>\n\n\n\n
This article explains what backdrill does, when it matters, and how to specify it correctly for a communication backplane PCB.<\/p>\n\n\n\n
A plated through-hole (PTH) often connects only some layers. The unused portion becomes a via stub<\/strong>\u2014a small resonant structure that can reflect energy and distort signals. Backdrilling removes the unused portion by drilling from one side after plating, reducing stub length.<\/p>\n\n\n\n In backplanes with long channels and multiple transitions, stub effects can stack up and reduce eye margin.<\/p>\n\n\n\n Backdrill is most commonly considered when you have:<\/p>\n\n\n\n If your design has short routes, low speeds, or minimal PTH transitions on critical nets, backdrill may not deliver enough benefit to justify cost.<\/p>\n\n\n\n The best strategy is selective backdrill:<\/p>\n\n\n\n This keeps SI improvement where it matters most while controlling cost.<\/p>\n\n\n\n To avoid ambiguity, define backdrill in build notes with:<\/p>\n\n\n\n If you don\u2019t know the ideal stub length, provide your data rate class and via structure. A capable manufacturer can suggest a practical target based on manufacturability and risk.<\/p>\n\n\n\n CTA:<\/strong> Send your backplane files and critical channel requirements. We\u2019ll review via structures and propose a selective backdrill approach for better SI without unnecessary cost.<\/p>","protected":false},"excerpt":{"rendered":" Backdrilling is one of the most effective manufacturing techniques for improving signal integrity in high-speed backplanes\u2014but it\u2019s also frequently misunderstood. Some teams request backdrill on every via \u201cjust in case,\u201d which can increase cost and risk without real benefit. Others skip it entirely and later struggle with resonances caused by via stubs. This article explains […]<\/p>\n","protected":false},"author":1,"featured_media":342,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1],"tags":[],"class_list":["post-130","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news"],"acf":[],"yoast_head":"\n2) When Backdrill Is Usually Worth Considering<\/h3>\n\n\n\n
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3) How to Decide: Focus on Critical Nets<\/h3>\n\n\n\n
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4) How to Specify Backdrill Correctly<\/h3>\n\n\n\n
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5) Common Mistakes to Avoid<\/h3>\n\n\n\n
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6) What to Send for Fast Backdrill Evaluation<\/h3>\n\n\n\n
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