{"id":19043,"date":"2026-09-16T14:05:03","date_gmt":"2026-09-16T05:05:03","guid":{"rendered":"https:\/\/www.japanunix.com\/en\/?post_type=column&#038;p=19043"},"modified":"2026-10-14T18:04:48","modified_gmt":"2026-10-14T09:04:48","slug":"steve_non_wetting_temperature","status":"publish","type":"column","link":"https:\/\/www.japanunix.com\/en\/column\/steve_non_wetting_temperature\/","title":{"rendered":"Solder Non-Wetting: Don\u2019t Turn Up the Temperature [Steve\u2019s Tech Article]"},"content":{"rendered":"<h3>Table of Contents<\/h3>\n<ul class=\"list-contents\">\n<li><a href=\"#01\">What Is Non-Wetting? \u2014 The Most Common Defect<\/a><\/li>\n<li><a href=\"#02\">The Common Mistake \u2014 Raising the Temperature Is the Last Resort<\/a><\/li>\n<li><a href=\"#03\">What Actually Causes It \u2014 ~38% Heat-Related, ~62% Workpiece Condition, Flux Deactivation, and Other<\/a><\/li>\n<li><a href=\"#04\">Flux Before Solder \u2014 Flux Clears the Road First<\/a><\/li>\n<li><a href=\"#05\">350\u00b0C vs. 410\u00b0C \u2014 What Happens When You Raise the Temperature<\/a><\/li>\n<li><a href=\"#06\">What to Check \u2014 Temperature Comes Last<\/a><\/li>\n<li><a href=\"#07\">Summary<\/a><\/li>\n<li><a href=\"#08\">Related Products &amp; Services<\/a><\/li>\n<li><a href=\"#09\">Video for This Tech Article<\/a><\/li>\n<\/ul>\n<hr class=\"hr-color-dark\">\n<div id=\"00\" class=\"c-box\">\n<div class=\"row\">\n<div class=\"col-md-5\">\n<p><a class=\"btn-primary btn-icon-next\" href=\"https:\/\/www.japanunix.com\/en\/products\/automation\/\">Explore Automated Soldering Robots<\/a><\/p>\n<p><a class=\"btn-primary btn-icon-next\" href=\"https:\/\/www.japanunix.com\/en\/products\/laser\/\">Explore Laser Soldering Systems<\/a><\/p>\n<\/div>\n<div class=\"col-md-7\">\n<div class=\"js-modal-video\" data-modal=\"#modal-media-target\" data-video-id=\"zhD2HMpEubs\">\n<div class=\"_thumb\"><img decoding=\"async\" src=\"https:\/\/img.youtube.com\/vi\/zhD2HMpEubs\/maxresdefault.jpg\" alt=\"\" \/><\/div>\n<\/div>\n<h5>Video for this Tech Article<\/h5>\n<\/div>\n<\/div>\n<\/div>\n<div id=\"01\" class=\"c-box\">\n<div class=\"row\">\n<div class=\"col-md-12\">\n<h2 class=\"heading-title\">What Is Non-Wetting? \u2014 The Most Common Defect<\/h2>\n<\/div>\n<\/div>\n<div class=\"row\">\n<div class=\"col-md-12\">\n<p><span class=\"label-primary\">S<\/span> Hello everyone. I&#8217;m Steve, a soldering engineer at Japan Unix.<\/p>\n<p>Today I want to talk about <strong>non-wetting<\/strong>, the most common defect in automated soldering. In our in-house records, non-wetting accounts for roughly half of all recorded defect modes.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div id=\"02\" class=\"c-box\">\n<div class=\"row\">\n<div class=\"col-md-12\">\n<h2 class=\"heading-title\">The Common Mistake \u2014 Raising the Temperature Is the Last Resort<\/h2>\n<\/div>\n<\/div>\n<div class=\"row\">\n<div class=\"col-md-6 order-md-2\">\n<p><span class=\"label-primary\">S<\/span> When non-wetting shows up, <strong>the first thing you must not do is raise the temperature.<\/strong> Raising the temperature should be your last resort.<\/p>\n<p>On the floor, &#8220;if it&#8217;s not wetting, raise the heat&#8221; is often the reflex fix \u2014 but that&#8217;s a coin flip at best. When it&#8217;s the wrong call, it doesn&#8217;t just fail to help; it can make things worse.<\/p>\n<\/div>\n<div class=\"col-md-6 order-md-1\">\n<div class=\"_image align-center mb-4\"><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/www.japanunix.com\/wp\/wp-content\/uploads\/2026\/09\/fig01_temp_x_en.png\" alt=\"The first thing not to do when non-wetting appears. A large X over a soldering iron tip with a thermometer icon. Raising the temperature should be your last resort\" width=\"1200\" height=\"675\"><\/div>\n<\/div>\n<\/div>\n<\/div>\n<div id=\"03\" class=\"c-box\">\n<div class=\"row\">\n<div class=\"col-md-12\">\n<h2 class=\"heading-title\">What Actually Causes It \u2014 ~38% Heat-Related, ~62% Workpiece Condition, Flux Deactivation, and Other<\/h2>\n<\/div>\n<\/div>\n<div class=\"row\">\n<div class=\"col-md-6 order-md-1\">\n<p><span class=\"label-primary\">S<\/span> When we actually counted the causes, <strong>workpiece condition, flux deactivation, and other factors made up about 62%, and heat-related causes were about 38%.<\/strong> Heat is not the only cause.<\/p>\n<p>Heat-related causes are still nearly 4 in 10 \u2014 this isn&#8217;t &#8220;heat doesn&#8217;t matter.&#8221; But there&#8217;s no data-backed reason to reach for the temperature dial first while setting aside the roughly 6 in 10 causes that have nothing to do with heat.<\/p>\n<\/div>\n<div class=\"col-md-6 order-md-2\">\n<div class=\"_image align-center mb-4\"><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/www.japanunix.com\/wp\/wp-content\/uploads\/2026\/09\/fig02_cause_distribution_en.png\" alt=\"Donut chart of non-wetting cause categories. Heat-related about 38%, workpiece condition \/ flux deactivation \/ other about 62%\" width=\"1200\" height=\"675\"><\/div>\n<\/div>\n<\/div>\n<table>\n<thead>\n<tr>\n<th>Non-Wetting Cause Category<\/th>\n<th>Share<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Workpiece condition, flux deactivation, other<\/td>\n<td><strong>~62%<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Heat-related (insufficient heat, heat capacity, position)<\/td>\n<td><strong>~38%<\/strong><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div id=\"04\" class=\"c-box\">\n<div class=\"row\">\n<div class=\"col-md-12\">\n<h2 class=\"heading-title\">Flux Before Solder \u2014 Flux Clears the Road First<\/h2>\n<\/div>\n<\/div>\n<div class=\"row\">\n<div class=\"col-md-6 order-md-2\">\n<p><span class=\"label-primary\">S<\/span> Flux lives inside the solder wire. Flux melts at 80\u2013120\u00b0C, and lead-free solder melts at 217\u00b0C.<\/p>\n<p>Flux is lighter and melts first, flowing out ahead of the solder. So the correct order is: <strong>flux flows first and strips the oxide film, and the solder follows the path it clears<\/strong> \u2014 that&#8217;s the mechanism. Flux&#8217;s job is to clear the road for the solder that follows.<\/p>\n<\/div>\n<div class=\"col-md-6 order-md-1\">\n<div class=\"_image align-center mb-4\"><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/www.japanunix.com\/wp\/wp-content\/uploads\/2026\/09\/fig03_flux_order_en.png\" alt=\"Solder cross-section diagram. Flux works at 80-120C and lead-free solder melts at 217C. Flux flows first to remove the oxide film, and solder follows the path it clears\" width=\"1200\" height=\"675\"><\/div>\n<\/div>\n<\/div>\n<\/div>\n<div id=\"05\" class=\"c-box\">\n<div class=\"row\">\n<div class=\"col-md-12\">\n<h2 class=\"heading-title\">350\u00b0C vs. 410\u00b0C \u2014 What Happens When You Raise the Temperature<\/h2>\n<\/div>\n<\/div>\n<div class=\"row\">\n<div class=\"col-md-6 order-md-1\">\n<p><span class=\"label-primary\">S<\/span> When we actually compared 350\u00b0C and 410\u00b0C, the 410\u00b0C tip spread well at first, but <strong>it can deactivate partway through.<\/strong> The road-clearing crew \u2014 the flux \u2014 burns out before the solder arrives.<\/p>\n<p>In other words, if the workpiece surface is the real cause of non-wetting, raising the temperature can burn off the very flux that would have cleaned that surface, before the solder gets its chance.<\/p>\n<\/div>\n<div class=\"col-md-6 order-md-2\">\n<div class=\"_image align-center mb-4\"><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/www.japanunix.com\/wp\/wp-content\/uploads\/2026\/09\/fig04_350_410_compare_en.png\" alt=\"Comparison of 350C and 410C soldering iron tip temperature. The 410C side spreads well at first but the flux deactivates partway through\" width=\"1200\" height=\"675\"><\/div>\n<\/div>\n<\/div>\n<\/div>\n<div id=\"06\" class=\"c-box\">\n<div class=\"row\">\n<div class=\"col-md-12\">\n<h2 class=\"heading-title\">What to Check \u2014 Temperature Comes Last<\/h2>\n<\/div>\n<\/div>\n<div class=\"row\">\n<div class=\"col-md-6 order-md-2\">\n<p><span class=\"label-primary\">S<\/span> So let&#8217;s look at what to check first: <strong>contact time, contact position, how you measure temperature, the tip, solder material, and workpiece surface. Temperature is the last thing to check.<\/strong><\/p>\n<p>This is a suggested order for what to check first \u2014 not a set of steps for what to change. Whether and how you actually change any setting, condition, or material is a decision for you to make under your own change-management procedure.<\/p>\n<\/div>\n<div class=\"col-md-6 order-md-1\">\n<div class=\"_image align-center mb-4\"><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/www.japanunix.com\/wp\/wp-content\/uploads\/2026\/09\/fig05_checklist_en.png\" alt=\"Checklist of points to check for non-wetting: contact time, contact position, temperature measurement, tip, solder material, workpiece surface, in that order, with temperature last\" width=\"1200\" height=\"675\"><\/div>\n<\/div>\n<\/div>\n<ol>\n<li><strong>Contact time<\/strong> \u2014 check whether the current setting matches the actual dwell time of the tip<\/li>\n<li><strong>Contact position<\/strong> \u2014 check the fixture, workpiece lift or warp, and feed position for misalignment<\/li>\n<li><strong>Temperature measurement<\/strong> \u2014 check the actual measured value, not the setpoint<\/li>\n<li><strong>Tip condition<\/strong> \u2014 check for carbonized residue, oxidation, wetted surface, and cleaning state<\/li>\n<li><strong>Solder material<\/strong> \u2014 check flux activity and properties such as halogen-free or high-viscosity formulations<\/li>\n<li><strong>Workpiece surface<\/strong> \u2014 check for oxidation, contamination, and storage condition<\/li>\n<li><strong>Only then, and only with high heat-capacity workpieces, does temperature become a relevant question<\/strong> \u2014 and temperature is an equipment setting, so whether to change it is your decision, made under your own change-management procedure (4M change control) and your own approval<\/li>\n<\/ol>\n<\/div>\n<div id=\"07\" class=\"c-box\">\n<div class=\"row\">\n<div class=\"col-md-12\">\n<h2 class=\"heading-title\">Summary<\/h2>\n<ul>\n<li>Non-wetting is the most common defect \u2014 but the cause isn&#8217;t always heat (heat-related is only about 38%)<\/li>\n<li>Raising the temperature can backfire by deactivating the flux before it does its job<\/li>\n<li>Check in this order: contact time \u2192 contact position \u2192 temperature measurement \u2192 tip \u2192 solder material \u2192 workpiece surface \u2192 temperature last<\/li>\n<\/ul>\n<p><span class=\"label-primary\">S<\/span> Non-wetting is the most common defect. But the cause isn&#8217;t always heat. There are things worth checking before you consider the temperature.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"panel-light\">\n<div class=\"_header\">Download Now<\/div>\n<div class=\"_body\">\n<div class=\"row\">\n<div class=\"col-md-4\">\n<div class=\"_image align-center mb-4\"><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/www.japanunix.com\/wp\/wp-content\/uploads\/2026\/09\/fig07_cta_pdf_en.png\" alt=\"Cover illustration of the Soldering Defect Troubleshooting Checklist (PDF document)\" width=\"778\" height=\"1068\"><\/div>\n<\/div>\n<div class=\"col-md-8\">\n<p><mark>When non-wetting appears in production: what to check before you raise the temperature, in one checklist.<\/mark><\/p>\n<p>The full checklist is in this one page. <strong>Soldering Defect Troubleshooting Checklist<\/strong> (2 pages, 31 items) \u2014 page 1 is the scan-and-check page for the floor, page 2 explains why each point is checked.<\/p>\n<p><a class=\"btn-primary btn-animation btn-block btn-icon-next\" href=\"https:\/\/www.japanunix.com\/en\/contact\/download_catalog#doc_handa\">Download the Soldering Defect Troubleshooting Checklist (Free)<\/a><\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<p>If you have other questions, feel free to reach out to Japan Unix.<\/p>\n<div id=\"08\" class=\"c-box\">\n<div class=\"row\">\n<div class=\"col-md-12\">\n<h2 class=\"heading-title\">Related Products &amp; Services<\/h2>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"c-box\">\n<div class=\"row\">\n<div class=\"col-md-12\">\n<p><a class=\"btn-primary btn-icon-next\" href=\"https:\/\/www.japanunix.com\/en\/products\/automation\/\">Explore Automated Soldering Robots<\/a><\/p>\n<p><a class=\"btn-primary btn-icon-next\" href=\"https:\/\/www.japanunix.com\/en\/products\/laser\/\">Explore Laser Soldering Systems<\/a><\/p>\n<\/div>\n<\/div>\n<\/div>\n<div id=\"09\" class=\"c-box\">\n<div class=\"row\">\n<div class=\"col-md-12\">\n<h2 class=\"heading-title\">Video for This Tech Article<\/h2>\n<\/div>\n<div class=\"col-md-6\">\n<div class=\"js-modal-video\" data-modal=\"#modal-media-target\" data-video-id=\"zhD2HMpEubs\">\n<div class=\"_thumb\"><img decoding=\"async\" src=\"https:\/\/img.youtube.com\/vi\/zhD2HMpEubs\/maxresdefault.jpg\" alt=\"\" \/><\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<p>Related document: <a href=\"https:\/\/www.japanunix.com\/en\/contact\/download_catalog#doc_handa\">Soldering Defect Troubleshooting Checklist (Free)<\/a><\/p>\n","protected":false},"featured_media":0,"template":"","column_category":[296,309,297,304],"column_tag":[],"acf":[],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.japanunix.com\/en\/wp-json\/wp\/v2\/column\/19043"}],"collection":[{"href":"https:\/\/www.japanunix.com\/en\/wp-json\/wp\/v2\/column"}],"about":[{"href":"https:\/\/www.japanunix.com\/en\/wp-json\/wp\/v2\/types\/column"}],"wp:attachment":[{"href":"https:\/\/www.japanunix.com\/en\/wp-json\/wp\/v2\/media?parent=19043"}],"wp:term":[{"taxonomy":"column_category","embeddable":true,"href":"https:\/\/www.japanunix.com\/en\/wp-json\/wp\/v2\/column_category?post=19043"},{"taxonomy":"column_tag","embeddable":true,"href":"https:\/\/www.japanunix.com\/en\/wp-json\/wp\/v2\/column_tag?post=19043"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}