{"id":9469,"date":"2025-06-24T17:45:09","date_gmt":"2025-06-24T09:45:09","guid":{"rendered":"http:\/\/www.bestpcbs.com\/blog\/?p=9469"},"modified":"2025-07-16T11:04:06","modified_gmt":"2025-07-16T03:04:06","slug":"pcb-layer-count-and-thickness-why-1-6mm-isnt-always-just-1-6mm","status":"publish","type":"post","link":"https:\/\/www.bestpcbs.com\/blog\/2025\/06\/pcb-layer-count-and-thickness-why-1-6mm-isnt-always-just-1-6mm\/","title":{"rendered":"PCB Layer Count and Thickness: Why 1.6mm Isn&#8217;t Always Just 1.6mm"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_82_2 ez-toc-wrap-left counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Table of Contents<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/www.bestpcbs.com\/blog\/2025\/06\/pcb-layer-count-and-thickness-why-1-6mm-isnt-always-just-1-6mm\/#A_Closer_Look_at_6-Layer_PCBs_with_Heavy_Copper\" >A Closer Look at 6-Layer PCBs with Heavy Copper<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/www.bestpcbs.com\/blog\/2025\/06\/pcb-layer-count-and-thickness-why-1-6mm-isnt-always-just-1-6mm\/#When_More_Layers_Matter_12-Layer_PCBs_and_Beyond\" >When More Layers Matter: 12-Layer PCBs and Beyond<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/www.bestpcbs.com\/blog\/2025\/06\/pcb-layer-count-and-thickness-why-1-6mm-isnt-always-just-1-6mm\/#Thickness_Materials_and_Dielectric_Strength\" >Thickness, Materials, and Dielectric Strength<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/www.bestpcbs.com\/blog\/2025\/06\/pcb-layer-count-and-thickness-why-1-6mm-isnt-always-just-1-6mm\/#Conclusion\" >Conclusion<\/a><\/li><\/ul><\/nav><\/div>\n<div class=\"yzp-no-index\"><\/div>\n<p><a href=\"https:\/\/www.bestpcbs.com\/\" title=\"\">Printed Circuit Boards (PCBs) <\/a>come in a variety of layer configurations and thicknesses, each suited to specific electrical and mechanical needs. One of the most common total thicknesses in the industry is <strong>1.6mm<\/strong>, but depending on copper weight and dielectric material selection, the actual thickness can vary\u2014sometimes leaning closer to <strong>1.7mm<\/strong>, especially in high copper-weight designs.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><a href=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2025\/06\/heavy-copper-pcb.jpg\"><img loading=\"lazy\" decoding=\"async\" width=\"605\" height=\"454\" src=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2025\/06\/heavy-copper-pcb.jpg\" alt=\"PCB Layer Count and Thickness: Why 1.6mm Isn't Always Just 1.6mm\" class=\"wp-image-9470\" srcset=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2025\/06\/heavy-copper-pcb.jpg 605w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2025\/06\/heavy-copper-pcb-300x225.jpg 300w\" sizes=\"auto, (max-width: 605px) 100vw, 605px\" \/><\/a><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"A_Closer_Look_at_6-Layer_PCBs_with_Heavy_Copper\"><\/span>A Closer Look at 6-Layer PCBs with Heavy Copper<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>For example, a <a href=\"https:\/\/www.bestpcbs.com\/blog\/2025\/06\/pcb-layer-count-and-thickness-why-1-6mm-isnt-always-just-1-6mm\/\" title=\"\"><strong>6-layer PCB<\/strong> <\/a>with <strong>4oz copper<\/strong> on all layers and a nominal thickness of <strong>1.6mm<\/strong> can practically reach <strong>1.68mm<\/strong>. This is because each 4oz copper layer measures about <strong>35\u00b5m<\/strong>, and the dielectric materials\u2014commonly <strong>Prepreg (PP)<\/strong>\u2014must be of equal or compatible thickness to match the structural and electrical integrity.<\/p>\n\n\n\n<p><strong>Thickness Calculation Example<\/strong>:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>4oz copper \u2248 140\u00b5m per layer (both sides)<\/li>\n\n\n\n<li>Dielectric material (PP) thickness \u2248 matches the copper layers<\/li>\n\n\n\n<li>Total stack-up: 4oz \u00d7 35\u00b5m \u00d7 6 layers \u00d7 2 (copper + PP) = ~1.68mm<\/li>\n<\/ul>\n\n\n\n<p>Such a construction is ideal when <strong>higher current-carrying capacity<\/strong>, <strong>thermal performance<\/strong>, and <strong>mechanical strength<\/strong> are required\u2014for example, <strong>power distribution boards<\/strong>, <strong>automotive controllers<\/strong>, and <strong>industrial automation equipment<\/strong>.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><a href=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2025\/06\/DSC_0517.jpg\"><img loading=\"lazy\" decoding=\"async\" width=\"773\" height=\"513\" src=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2025\/06\/DSC_0517.jpg\" alt=\"6-Layer PCBs with Heavy Copper\" class=\"wp-image-9471\" srcset=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2025\/06\/DSC_0517.jpg 773w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2025\/06\/DSC_0517-300x199.jpg 300w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2025\/06\/DSC_0517-768x510.jpg 768w\" sizes=\"auto, (max-width: 773px) 100vw, 773px\" \/><\/a><\/figure>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"When_More_Layers_Matter_12-Layer_PCBs_and_Beyond\"><\/span>When More Layers Matter: 12-Layer PCBs and Beyond<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>As systems grow more complex, 12-layer PCBs are commonly used in high-speed data communication, AI computing platforms, and server mainboards. These applications require not only signal integrity but also EMI shielding, controlled impedance, and dedicated power\/ground planes.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>A 12-layer stack-up typically includes:<\/li>\n\n\n\n<li>Multiple signal layers for differential pairs and high-speed routing<\/li>\n\n\n\n<li>Dedicated ground and power planes<\/li>\n\n\n\n<li>Carefully chosen PP and core materials to maintain <strong>target thickness<\/strong> (often still around 1.6mm)<\/li>\n<\/ul>\n\n\n\n<p>Maintaining 1.6mm with more layers means thinner individual dielectric layers and copper foils, making material selection and lamination control critical.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><a href=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2025\/06\/DSC_0858-1.jpg\"><img loading=\"lazy\" decoding=\"async\" width=\"644\" height=\"428\" src=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2025\/06\/DSC_0858-1.jpg\" alt=\"12-Layer PCBs\" class=\"wp-image-9473\" srcset=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2025\/06\/DSC_0858-1.jpg 644w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2025\/06\/DSC_0858-1-300x199.jpg 300w\" sizes=\"auto, (max-width: 644px) 100vw, 644px\" \/><\/a><\/figure>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Thickness_Materials_and_Dielectric_Strength\"><\/span>Thickness, Materials, and Dielectric Strength<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>The interplay between <strong><a href=\"https:\/\/www.bestpcbs.com\/blog\/2025\/06\/pcb-layer-count-and-thickness-why-1-6mm-isnt-always-just-1-6mm\/\" title=\"\">copper thickness<\/a><\/strong>, <strong>prepreg<\/strong>, and <strong>core<\/strong> materials affects not only the final PCB thickness but also <strong>electrical isolation<\/strong> and <strong>breakdown voltage<\/strong>. Thicker copper increases current capacity but reduces the available space for dielectric layers\u2014potentially compromising <strong>dielectric strength<\/strong> if not properly managed.<\/p>\n\n\n\n<p><strong>To ensure breakdown voltage requirements are met<\/strong>, manufacturers must:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Use high-quality, high-resin content prepregs<\/li>\n\n\n\n<li>Maintain minimum dielectric spacing between high-voltage nets<\/li>\n\n\n\n<li>Control resin flow during lamination to avoid thin spots<\/li>\n<\/ul>\n\n\n\n<p>For example, <strong><a href=\"https:\/\/www.bestpcbs.com\/products\/FR4-pcb.htm\" title=\"\">FR-4-based PCBs<\/a><\/strong> typically require at least <strong>100\u00b5m spacing<\/strong> to withstand <strong>500V or more<\/strong>, depending on the resin system.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Conclusion\"><\/span>Conclusion<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>While <strong>1.6mm<\/strong> is a standard thickness in <a href=\"https:\/\/www.bestpcbs.com\/manufacturing\/pcb-manufacturing.htm\" title=\"\">PCB manufacturing<\/a>, <strong>the internal layer structure determines the real-world electrical and mechanical performance<\/strong>. From <strong>6-layer power boards<\/strong> with 4oz copper to <strong>12-layer high-speed boards<\/strong>, designers must strike a balance between <strong>copper weight<\/strong>, <strong>material thickness<\/strong>, and <strong>breakdown strength<\/strong>.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Printed Circuit Boards (PCBs) come in a variety of layer configurations and thicknesses, each suited to specific electrical and mechanical needs. One of the most common total thicknesses in the industry is 1.6mm, but depending on copper weight and dielectric material selection, the actual thickness can vary\u2014sometimes leaning closer to 1.7mm, especially in high copper-weight [&hellip;]<\/p>\n","protected":false},"author":623,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_uf_show_specific_survey":0,"_uf_disable_surveys":false,"footnotes":""},"categories":[175,174,164,37],"tags":[118,1637,378],"class_list":["post-9469","post","type-post","status-publish","format-standard","hentry","category-best-pcb","category-bestpcb","category-design-guide","category-faq","tag-heavy-copper-pcb","tag-pcb-layer-count","tag-pcb-thickness"],"acf":[],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/posts\/9469","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/users\/623"}],"replies":[{"embeddable":true,"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/comments?post=9469"}],"version-history":[{"count":5,"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/posts\/9469\/revisions"}],"predecessor-version":[{"id":10371,"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/posts\/9469\/revisions\/10371"}],"wp:attachment":[{"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/media?parent=9469"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/categories?post=9469"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/tags?post=9469"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}