{"id":6960,"date":"2026-07-28T09:00:00","date_gmt":"2026-07-28T01:00:00","guid":{"rendered":"https:\/\/www.metal-domes.com\/blog\/?p=6960"},"modified":"2026-07-28T08:47:05","modified_gmt":"2026-07-28T00:47:05","slug":"pcb-contact-pad-design-metal-dome-switches","status":"publish","type":"post","link":"https:\/\/www.metal-domes.com\/blog\/2026\/07\/28\/pcb-contact-pad-design-metal-dome-switches\/","title":{"rendered":"PCB Contact Pad Design for Metal Dome Switches"},"content":{"rendered":"<div class=\"yzp-no-index\"><\/div><div id=\"ez-toc-container\" class=\"ez-toc-v2_0_69_1 ez-toc-wrap-left counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<div class=\"ez-toc-title\" style=\"cursor:inherit\">Table of Contents<\/div>\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.metal-domes.com\/blog\/2026\/07\/28\/pcb-contact-pad-design-metal-dome-switches\/#What_Is_a_PCB_Contact_Pad_for_a_Metal_Dome_Switch\" title=\"What Is a PCB Contact Pad for a Metal Dome Switch?\">What Is a PCB Contact Pad for a Metal Dome Switch?<\/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.metal-domes.com\/blog\/2026\/07\/28\/pcb-contact-pad-design-metal-dome-switches\/#How_Does_a_Metal_Dome_Close_the_Electrical_Contact_Pad\" title=\"How Does a Metal Dome Close the Electrical Contact Pad?\">How Does a Metal Dome Close the Electrical Contact Pad?<\/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.metal-domes.com\/blog\/2026\/07\/28\/pcb-contact-pad-design-metal-dome-switches\/#Which_PCB_Contact_Pad_Layout_Should_You_Use\" title=\"Which PCB Contact Pad Layout Should You Use?\">Which PCB Contact Pad Layout Should You Use?<\/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.metal-domes.com\/blog\/2026\/07\/28\/pcb-contact-pad-design-metal-dome-switches\/#How_Should_the_Center_Pad_and_Outer_Contact_Be_Dimensioned\" title=\"How Should the Center Pad and Outer Contact Be Dimensioned?\">How Should the Center Pad and Outer Contact Be Dimensioned?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/www.metal-domes.com\/blog\/2026\/07\/28\/pcb-contact-pad-design-metal-dome-switches\/#How_Much_Clearance_Is_Required_Around_the_Dome\" title=\"How Much Clearance Is Required Around the Dome?\">How Much Clearance Is Required Around the Dome?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/www.metal-domes.com\/blog\/2026\/07\/28\/pcb-contact-pad-design-metal-dome-switches\/#Should_Solder_Mask_Be_Used_Between_Contact_Areas\" title=\"Should Solder Mask Be Used Between Contact Areas?\">Should Solder Mask Be Used Between Contact Areas?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/www.metal-domes.com\/blog\/2026\/07\/28\/pcb-contact-pad-design-metal-dome-switches\/#Which_Surface_Finish_Is_Best_for_a_PCB_Contact_Pad\" title=\"Which Surface Finish Is Best for a PCB Contact Pad?\">Which Surface Finish Is Best for a PCB Contact Pad?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/www.metal-domes.com\/blog\/2026\/07\/28\/pcb-contact-pad-design-metal-dome-switches\/#Why_Does_Metal_Dome_Venting_Affect_Contact_Performance\" title=\"Why Does Metal Dome Venting Affect Contact Performance?\">Why Does Metal Dome Venting Affect Contact Performance?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/www.metal-domes.com\/blog\/2026\/07\/28\/pcb-contact-pad-design-metal-dome-switches\/#Where_Should_Vias_and_Traces_Be_Placed\" title=\"Where Should Vias and Traces Be Placed?\">Where Should Vias and Traces Be Placed?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/www.metal-domes.com\/blog\/2026\/07\/28\/pcb-contact-pad-design-metal-dome-switches\/#How_Do_Pad_Designs_Change_for_Different_Dome_Shapes\" title=\"How Do Pad Designs Change for Different Dome Shapes?\">How Do Pad Designs Change for Different Dome Shapes?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/www.metal-domes.com\/blog\/2026\/07\/28\/pcb-contact-pad-design-metal-dome-switches\/#How_Should_a_Dome_Array_Align_with_PCB_Contact_Pads\" title=\"How Should a Dome Array Align with PCB Contact Pads?\">How Should a Dome Array Align with PCB Contact Pads?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-12\" href=\"https:\/\/www.metal-domes.com\/blog\/2026\/07\/28\/pcb-contact-pad-design-metal-dome-switches\/#What_Should_Be_Checked_Before_Assembly\" title=\"What Should Be Checked Before Assembly?\">What Should Be Checked Before Assembly?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-13\" href=\"https:\/\/www.metal-domes.com\/blog\/2026\/07\/28\/pcb-contact-pad-design-metal-dome-switches\/#FAQ_About_PCB_Contact_Pads\" title=\"FAQ About PCB Contact Pads?\">FAQ About PCB Contact Pads?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-14\" href=\"https:\/\/www.metal-domes.com\/blog\/2026\/07\/28\/pcb-contact-pad-design-metal-dome-switches\/#Conclusion\" title=\"Conclusion\">Conclusion<\/a><\/li><\/ul><\/nav><\/div>\n\n\n\n<p>A <a href=\"https:\/\/www.metal-domes.com\/blog\/2026\/07\/28\/pcb-contact-pad-design-metal-dome-switches\/\">PCB Contact Pad<\/a> for a metal dome switch normally consists of an isolated center contact and an outer contact area. The metal dome rests on the outer contact while remaining above the center pad. Pressing the dome makes its center bridge both conductors, closing a momentary, normally open circuit. Reliable operation depends on pad geometry, flatness, surface finish, solder-mask clearance, venting and alignment with the dome.<\/p>\n\n<div class=\"wp-block-image\">\n  <figure class=\"aligncenter size-large is-resized\">\n    <a href=\"https:\/\/www.metal-domes.com\/blog\/wp-content\/uploads\/2026\/07\/pcb-contact-pad-metal-dome-hero-v2.jpg\"><img decoding=\"async\" src=\"https:\/\/www.metal-domes.com\/blog\/wp-content\/uploads\/2026\/07\/pcb-contact-pad-metal-dome-hero-v2.jpg\" alt=\"PCB Contact Pad under a real four-leg metal dome switch\" width=\"600\" class=\"wp-image-6962\" srcset=\"https:\/\/www.metal-domes.com\/blog\/wp-content\/uploads\/2026\/07\/pcb-contact-pad-metal-dome-hero-v2.jpg 600w, https:\/\/www.metal-domes.com\/blog\/wp-content\/uploads\/2026\/07\/pcb-contact-pad-metal-dome-hero-v2-300x200.jpg 300w\" sizes=\"(max-width: 600px) 100vw, 600px\" \/><\/a>\n  <\/figure>\n<\/div>\n\n<p>The pad should be designed from the selected dome drawing rather than from a generic footprint. A circular dome, four-leg dome and triangle dome touch the PCB at different locations. The surrounding adhesive, array carrier and housing also add mechanical constraints that are absent from an ordinary solder pad.<\/p>\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"What_Is_a_PCB_Contact_Pad_for_a_Metal_Dome_Switch\"><\/span>What Is a PCB Contact Pad for a Metal Dome Switch?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n<p>A PCB contact pad is the exposed conductive pattern that the metal dome electrically bridges during a key press. The center pad is one electrical node. The surrounding ring, segmented arcs or leg pads form the second node. In the released state, the arched dome touches only the outer node; at full actuation, its center also touches the center node.<\/p>\n\n<p>This contact is mechanical and repeatable, not a solder joint. The exposed surface must remain flat, conductive and resistant to oxidation or contamination. Copper geometry alone is therefore insufficient: the final pad includes copper, plating, solder-mask opening, nearby routing and the local board topography.<\/p>\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"How_Does_a_Metal_Dome_Close_the_Electrical_Contact_Pad\"><\/span>How Does a Metal Dome Close the Electrical Contact Pad?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n<p>The dome acts as both a spring and a movable conductor. Force applied near its crown causes a snap-through transition. At the bottom of travel, the dome center touches the center contact while its rim or legs remain connected to the outer contact. Current can then pass between the two PCB nets.<\/p>\n\n<p>The center pad should not contact the dome before the snap point. Residual copper height, solder, contamination, raised via fill or an uneven finish can reduce the air gap and create intermittent conduction. Conversely, a center contact that is too small or too far from the dome&#8217;s contact point may require excessive travel or produce unstable closure.<\/p>\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Which_PCB_Contact_Pad_Layout_Should_You_Use\"><\/span>Which PCB Contact Pad Layout Should You Use?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n<p>Select the layout from the dome&#8217;s actual support points. Circle domes commonly use a central disc with a continuous or segmented outer ring. Four-leg domes may use a center feature surrounded by four outer landing areas. Triangle domes need three correctly positioned support contacts. The electrical topology remains two-node, but the copper shape changes with the mechanical footprint.<\/p>\n\n<div class=\"wp-block-image\">\n  <figure class=\"aligncenter size-large is-resized\">\n    <a href=\"https:\/\/www.metal-domes.com\/blog\/wp-content\/uploads\/2026\/07\/pcb-contact-pad-layout-types-v2.jpg\"><img decoding=\"async\" src=\"https:\/\/www.metal-domes.com\/blog\/wp-content\/uploads\/2026\/07\/pcb-contact-pad-layout-types-v2.jpg\" alt=\"Real circle, four-leg and triangle metal domes with matching PCB contact pad layouts\" width=\"600\" class=\"wp-image-6963\" srcset=\"https:\/\/www.metal-domes.com\/blog\/wp-content\/uploads\/2026\/07\/pcb-contact-pad-layout-types-v2.jpg 600w, https:\/\/www.metal-domes.com\/blog\/wp-content\/uploads\/2026\/07\/pcb-contact-pad-layout-types-v2-300x200.jpg 300w\" sizes=\"(max-width: 600px) 100vw, 600px\" \/><\/a>\n  <\/figure>\n<\/div>\n\n<p>A single-sided contact pattern is convenient because both nodes and the dome sit on the same board face. Routing may leave through narrow necks or move to another layer through vias placed outside the active contact and seating regions. A double-sided board does not change the contact principle; it only provides more routing freedom.<\/p>\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"How_Should_the_Center_Pad_and_Outer_Contact_Be_Dimensioned\"><\/span>How Should the Center Pad and Outer Contact Be Dimensioned?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n<p>The center pad must cover the dome&#8217;s intended center-contact area with registration margin, while the outer copper must fully support every rim or leg contact over the worst-case positional tolerance. The insulating gap must remain wide enough to prevent copper bridging and narrow enough that the dome can bridge both nodes at full travel.<\/p>\n\n<p>Metal-Domes publishes the following sample dimensions for a single-sided four-leg pad layout. The lettered dimensions belong to that specific drawing and should be read together with the PDF, not copied into another pad geometry.<\/p>\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\">\n<thead>\n<tr>\n<th>Four-Leg Dome Size<\/th>\n<th>D<\/th>\n<th>T<\/th>\n<th>W<\/th>\n<th>P<\/th>\n<th>S<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr><td>5.0 mm<\/td><td>2.59 mm<\/td><td>1.67 mm<\/td><td>1.04 mm<\/td><td>2.03 mm<\/td><td>0.38 mm<\/td><\/tr>\n<tr><td>6.0 mm<\/td><td>2.96 mm<\/td><td>1.96 mm<\/td><td>1.09 mm<\/td><td>2.45 mm<\/td><td>0.64 mm<\/td><\/tr>\n<tr><td>7.0 mm<\/td><td>3.45 mm<\/td><td>2.28 mm<\/td><td>1.27 mm<\/td><td>2.86 mm<\/td><td>0.76 mm<\/td><\/tr>\n<tr><td>8.4 mm<\/td><td>4.19 mm<\/td><td>2.77 mm<\/td><td>1.55 mm<\/td><td>3.48 mm<\/td><td>0.92 mm<\/td><\/tr>\n<tr><td>10.0 mm<\/td><td>4.67 mm<\/td><td>3.15 mm<\/td><td>1.55 mm<\/td><td>4.08 mm<\/td><td>1.10 mm<\/td><\/tr>\n<tr><td>12.0 mm<\/td><td>5.59 mm<\/td><td>3.76 mm<\/td><td>1.85 mm<\/td><td>4.90 mm<\/td><td>1.30 mm<\/td><\/tr>\n<\/tbody>\n<\/table><\/figure>\n\n<p>Use the selected dome series drawing to establish the final values. Center-hole four-leg domes and special leg geometries may require a different pattern even when their nominal outer diameter is similar.<\/p>\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"How_Much_Clearance_Is_Required_Around_the_Dome\"><\/span>How Much Clearance Is Required Around the Dome?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n<p>Clearance must protect three zones: the electrical gap between the two nodes, the dome seating area and the dome&#8217;s moving envelope. Copper from unrelated nets, exposed test points, component pads and tall solder-mask features should stay outside these zones.<\/p>\n\n<ul class=\"wp-block-list\">\n<li>Keep the outer contact wide enough to retain contact at maximum dome-to-pad offset.<\/li>\n<li>Maintain a uniform insulating gap around the center pad; local necking can change the closure point.<\/li>\n<li>Keep components and protruding features beyond the dome outline plus assembly tolerance.<\/li>\n<li>Reserve an adhesive-bonding area outside the moving dome when a PET carrier or dome array is used.<\/li>\n<li>Check enclosure bosses, light guides and key guides against the same keepout, not only the PCB drawing.<\/li>\n<\/ul>\n\n<p>No single clearance value applies to every dome. Dome diameter, leg shape, lateral travel, placement tolerance, adhesive stack and board fabrication capability determine the final keepout.<\/p>\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Should_Solder_Mask_Be_Used_Between_Contact_Areas\"><\/span>Should Solder Mask Be Used Between Contact Areas?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n<p>Solder mask should normally be kept out of the active electrical contact areas and should not create a raised ridge between the center and outer contacts. A mask bridge can lift the dome, reduce available travel or prevent uniform seating. Mask encroachment can also reduce the effective contact width.<\/p>\n\n<p>Define one controlled opening around the complete contact pattern or use openings that leave the entire dome contact path clear. The final choice depends on mask registration capability and the need to protect nearby traces. Inspect the manufactured opening against the copper, because nominal CAD clearance does not reveal real mask shift or thickness variation.<\/p>\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Which_Surface_Finish_Is_Best_for_a_PCB_Contact_Pad\"><\/span>Which Surface Finish Is Best for a PCB Contact Pad?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n<p>A suitable finish provides a flat, oxidation-resistant and low-residue contact surface. ENIG is widely used because it is comparatively flat and protects the copper. Hard gold is useful where repeated sliding or abrasive contact makes wear resistance important. Carbon ink can provide a durable low-cost contact surface in appropriate membrane and keypad structures. HASL is available but its height variation makes it less attractive for small, precision dome contacts.<\/p>\n\n<div class=\"wp-block-image\">\n  <figure class=\"aligncenter size-large is-resized\">\n    <a href=\"https:\/\/www.metal-domes.com\/blog\/wp-content\/uploads\/2026\/07\/pcb-contact-pad-surface-finish.jpg\"><img decoding=\"async\" src=\"https:\/\/www.metal-domes.com\/blog\/wp-content\/uploads\/2026\/07\/pcb-contact-pad-surface-finish.jpg\" alt=\"ENIG, hard gold, carbon and HASL surface finishes on PCB contact pads\" width=\"600\" class=\"wp-image-6958\" srcset=\"https:\/\/www.metal-domes.com\/blog\/wp-content\/uploads\/2026\/07\/pcb-contact-pad-surface-finish.jpg 600w, https:\/\/www.metal-domes.com\/blog\/wp-content\/uploads\/2026\/07\/pcb-contact-pad-surface-finish-300x200.jpg 300w\" sizes=\"(max-width: 600px) 100vw, 600px\" \/><\/a>\n  <\/figure>\n<\/div>\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\">\n<thead>\n<tr><th>Finish<\/th><th>Useful Characteristic<\/th><th>Design Consideration<\/th><\/tr>\n<\/thead>\n<tbody>\n<tr><td>ENIG<\/td><td>Flat and oxidation resistant<\/td><td>Common starting choice for dome contact pads<\/td><\/tr>\n<tr><td>Hard gold<\/td><td>High wear resistance<\/td><td>Specify nickel\/gold system and contact requirements clearly<\/td><\/tr>\n<tr><td>Carbon ink<\/td><td>Durable printed contact surface<\/td><td>Thickness and curing must be controlled<\/td><\/tr>\n<tr><td>HASL<\/td><td>Widely available<\/td><td>Surface height variation can affect small contacts<\/td><\/tr>\n<\/tbody>\n<\/table><\/figure>\n\n<p>Finish selection should be confirmed with contact resistance, environmental exposure and cycling tests. See the detailed <a href=\"https:\/\/www.metal-domes.com\/blog\/2011\/10\/10\/pcb-pad-finishing-for-metal-dome\/\">PCB pad finishing guide for metal domes<\/a> for a deeper treatment of plating choices.<\/p>\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Why_Does_Metal_Dome_Venting_Affect_Contact_Performance\"><\/span>Why Does Metal Dome Venting Affect Contact Performance?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n<p>Venting allows air to leave and re-enter the cavity beneath the dome. Without a path, trapped air can oppose the downward stroke, slow release or push against the adhesive carrier. The resulting key can feel damped even when the dome and pad dimensions are correct.<\/p>\n\n<p>A vent channel should connect the dome cavity to open air without crossing an electrical contact, weakening the adhesive seal or creating a contamination path through a critical area. It can be formed in the spacer or adhesive pattern, or coordinated with a board-level vent where the construction permits. The dedicated <a href=\"https:\/\/www.metal-domes.com\/blog\/2026\/06\/11\/metal-dome-venting\/\">metal dome venting guide<\/a> explains channel layouts and common failures in more detail.<\/p>\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Where_Should_Vias_and_Traces_Be_Placed\"><\/span>Where Should Vias and Traces Be Placed?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n<p>Route traces away from the exposed contact and dome seating areas. A trace neck may leave a pad from the center or outer node, but it should not create a copper step under a support point. Vias are best placed outside the dome footprint and adhesive-bonding zone.<\/p>\n\n<p>If a via must be located beneath the assembly, use a verified filled and planarized construction and confirm that its finish cannot print through the contact surface. Tent-only vias can trap residue or leave a depression. Also keep test-probe marks outside the dome contact path; a probe dent or transferred debris can become a repeatable high-resistance point.<\/p>\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"How_Do_Pad_Designs_Change_for_Different_Dome_Shapes\"><\/span>How Do Pad Designs Change for Different Dome Shapes?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n<p>Pad geometry follows the dome&#8217;s stable support points. A round dome may sit on a continuous ring. A <a href=\"https:\/\/www.metal-domes.com\/product-photos\/four-legs-metal-dome.htm\">four-leg metal dome<\/a> transfers load and current through four defined legs, so each landing area must remain supported after placement tolerance is applied. A <a href=\"https:\/\/www.metal-domes.com\/product-photos\/triangle-metal-dome.htm\">triangle metal dome<\/a> uses three support regions and may need more orientation control.<\/p>\n\n<p>Oblong and custom domes introduce different center-contact locations and directional stiffness. Do not scale a circular footprint uniformly to fit them. Use the supplier drawing to locate the crown, support contacts, dimples, center holes and any legs that extend beyond the nominal body.<\/p>\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"How_Should_a_Dome_Array_Align_with_PCB_Contact_Pads\"><\/span>How Should a Dome Array Align with PCB Contact Pads?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n<p>The PCB, adhesive carrier and enclosure should share a consistent datum system. Alignment holes or external profiles on the array should reference PCB tooling features that also control the key guides. This prevents one correction at the housing from introducing a second offset at the contact pad.<\/p>\n\n<div class=\"wp-block-image\">\n  <figure class=\"aligncenter size-large is-resized\">\n    <a href=\"https:\/\/www.metal-domes.com\/blog\/wp-content\/uploads\/2026\/07\/pcb-contact-pad-dome-array-alignment.jpg\"><img decoding=\"async\" src=\"https:\/\/www.metal-domes.com\/blog\/wp-content\/uploads\/2026\/07\/pcb-contact-pad-dome-array-alignment.jpg\" alt=\"Dome array alignment over PCB contact pads using common datum holes\" width=\"600\" class=\"wp-image-6959\" srcset=\"https:\/\/www.metal-domes.com\/blog\/wp-content\/uploads\/2026\/07\/pcb-contact-pad-dome-array-alignment.jpg 600w, https:\/\/www.metal-domes.com\/blog\/wp-content\/uploads\/2026\/07\/pcb-contact-pad-dome-array-alignment-300x200.jpg 300w\" sizes=\"(max-width: 600px) 100vw, 600px\" \/><\/a>\n  <\/figure>\n<\/div>\n\n<p>For a multi-key array, evaluate translation, rotation, film stretch and accumulated pitch error. A center key may align while corner keys drift toward the edge of their pads. A transparent first-article overlay, fiducials or an optical inspection template can reveal the full-array pattern before final lamination. The <a href=\"https:\/\/www.metal-domes.com\/blog\/2026\/05\/08\/pcb-for-metal-dome-array\/\">PCB for metal dome array guide<\/a> covers the broader board-interface structure.<\/p>\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"What_Should_Be_Checked_Before_Assembly\"><\/span>What Should Be Checked Before Assembly?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n<p>Verify the electrical pattern and mechanical stack together before attaching the dome array. The following checks focus on measurable board and assembly conditions.<\/p>\n\n<ul class=\"wp-block-list\">\n<li>Confirm that center and outer contacts belong to separate nets and are electrically open before actuation.<\/li>\n<li>Measure critical pad dimensions against the approved dome drawing, including the narrowest contact width.<\/li>\n<li>Inspect solder-mask registration, plating flatness, scratches, residue and exposed copper.<\/li>\n<li>Confirm that vias, test points and unrelated traces do not enter the contact, seating or adhesive zones.<\/li>\n<li>Overlay the array drawing on the PCB data and verify every key position, not only the first pad.<\/li>\n<li>Check vent-channel continuity after adhesive lamination.<\/li>\n<li>Measure open and closed resistance on representative keys and record actuation force and return behavior.<\/li>\n<li>Cycle representative assemblies under the intended temperature, humidity and contamination conditions.<\/li>\n<\/ul>\n\n<p>A dimensional pass does not replace functional testing. Contact resistance, force curve, release, sound and repeated cycling expose interactions between the board, finish, dome and carrier that CAD data cannot show.<\/p>\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"FAQ_About_PCB_Contact_Pads\"><\/span>FAQ About PCB Contact Pads?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n<h3>Can a metal dome contact an untreated copper pad?<\/h3>\n<p>Bare copper oxidizes and its contact resistance can change with storage and environment. A controlled protective finish is normally preferred for a repeatable switch contact.<\/p>\n\n<h3>Can solder be added to improve a contact pad?<\/h3>\n<p>Solder usually makes the surface less flat and can leave flux residue, so it is not a reliable way to improve a mechanical dome contact. Use an appropriate specified finish instead.<\/p>\n\n<h3>Can a via be placed in the center pad?<\/h3>\n<p>It is better to route the via outside the active area. If space forces a via into the pad, it needs a verified filled and planarized construction with no depression, protrusion or residue at the dome contact point.<\/p>\n\n<h3>Do all metal dome shapes use a center pad and outer ring?<\/h3>\n<p>They use two electrical nodes, but the outer node may be a ring, arcs or separate leg landings. The copper geometry must match the selected dome&#8217;s actual support and contact locations.<\/p>\n\n<h3>Why does a clean pad still produce intermittent contact?<\/h3>\n<p>Possible causes include incorrect pad geometry, dome offset, uneven finish, insufficient travel, mask encroachment, a raised via, trapped air or damage to the dome contact surface. Inspect the complete stack rather than cleaning alone.<\/p>\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<p>A reliable <a href=\"https:\/\/www.metal-domes.com\/blog\/2026\/07\/28\/pcb-contact-pad-design-metal-dome-switches\/\">PCB Contact Pad<\/a> matches the selected dome&#8217;s support points, keeps the two electrical nodes flat and isolated, provides suitable plating and solder-mask clearance, and preserves a clear vent and alignment path. The design should be validated as a complete assembly because board topography, adhesive, dome placement and housing tolerances interact.<\/p>\n\n<p>EBest Circuit(Best Technology) supports standard and custom metal domes and <a href=\"https:\/\/www.metal-domes.com\/product\/dome-array-custom.htm\">custom dome arrays<\/a> for PCB, FPC and membrane-switch interfaces. Contact <a href=\"mailto:sales@metal-domes.com\">sales@metal-domes.com<\/a> for engineering support on pad-to-dome alignment and array integration.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>PCB Contact Pad design guide for metal dome switches covering layout, dimensions, clearance, solder mask, surface finish, venting and assembly checks. <a href=\"https:\/\/www.metal-domes.com\/blog\/2026\/07\/28\/pcb-contact-pad-design-metal-dome-switches\/\">Continue reading <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":57789,"featured_media":6962,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[100,9,3],"tags":[1242,20,1243,179,1241,1244,1245],"class_list":["post-6960","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-metal-dome-assembly-2","category-metal-dome-related","category-metal-domes","tag-contact-pad","tag-dome-array","tag-electrical-contact-pad","tag-metal-dome-switch","tag-pcb-contact-pad","tag-pcb-pad-design","tag-pcb-surface-finish"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.metal-domes.com\/blog\/wp-json\/wp\/v2\/posts\/6960","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.metal-domes.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.metal-domes.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.metal-domes.com\/blog\/wp-json\/wp\/v2\/users\/57789"}],"replies":[{"embeddable":true,"href":"https:\/\/www.metal-domes.com\/blog\/wp-json\/wp\/v2\/comments?post=6960"}],"version-history":[{"count":2,"href":"https:\/\/www.metal-domes.com\/blog\/wp-json\/wp\/v2\/posts\/6960\/revisions"}],"predecessor-version":[{"id":6964,"href":"https:\/\/www.metal-domes.com\/blog\/wp-json\/wp\/v2\/posts\/6960\/revisions\/6964"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.metal-domes.com\/blog\/wp-json\/wp\/v2\/media\/6962"}],"wp:attachment":[{"href":"https:\/\/www.metal-domes.com\/blog\/wp-json\/wp\/v2\/media?parent=6960"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.metal-domes.com\/blog\/wp-json\/wp\/v2\/categories?post=6960"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.metal-domes.com\/blog\/wp-json\/wp\/v2\/tags?post=6960"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}