{"id":39034,"date":"2021-12-01T06:00:00","date_gmt":"2021-12-01T12:00:00","guid":{"rendered":"https:\/\/flex.com\/resources\/immersive-cooling-proving-its-compatibility-with-dc-dc-converters"},"modified":"2026-03-17T12:51:05","modified_gmt":"2026-03-17T17:51:05","slug":"immersive-cooling-proving-its-compatibility-with-dc-dc-converters","status":"publish","type":"resource","link":"https:\/\/flex.com\/zh\/resources\/immersive-cooling-proving-its-compatibility-with-dc-dc-converters","title":{"rendered":"\u6d78\u6ca1\u5f0f\u51b7\u5374\u2014\u2014\u8bc1\u660e\u4e86\u5176\u4e0e\u76f4\u6d41\/\u76f4\u6d41\u8f6c\u6362\u5668\u7684\u517c\u5bb9\u6027"},"content":{"rendered":"<div id=\"overscroll-top\" style=\"background-color: #eaeef4;\"><\/div>\n<div class=\"resource-header block\">\n\t<div class=\"container\">\n\t\t<div class=\"breadcrumb\">\n\t\t\t<a title=\"Homepage\" href=\"\/\">Flex<\/a>\n\t\t\t<svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" viewBox=\"0 0 384 512\"><path d=\"M365.3 256l-22.6 22.6-192 192L128 493.3 82.7 448l22.6-22.6L274.7 256 105.4 86.6 82.7 64 128 18.7l22.6 22.6 192 192L365.3 256z\"\/><\/svg>\n\t\t\t<a title=\"Resources\" href=\"\/resources\">Resources<\/a>\n\t\t\t<svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" viewBox=\"0 0 384 512\"><path d=\"M365.3 256l-22.6 22.6-192 192L128 493.3 82.7 448l22.6-22.6L274.7 256 105.4 86.6 82.7 64 128 18.7l22.6 22.6 192 192L365.3 256z\"\/><\/svg>\n\t\t\t<a title=\"Immersive cooling \u2014 proving its compatibility with DC\/DC converters\">Immersive cooling \u2014 proving its compatibility with DC\/DC converters<\/a>\n\t\t<\/div>\n\t\t<h1>Immersive cooling \u2014 proving its compatibility with DC\/DC converters<\/h1>\n\t\t\t\t<div class=\"separator\"><\/div>\n\t\t<div class=\"details\">\n\t\t\t\t\t\t\t\t\t<div class=\"date detail\">\n\t\t\t\tPosted on<br>\n\t\t\t\t1 12 \u6708, 2021\t\t\t<\/div>\n\t\t\t\t\t\t<div class=\"categories\">\n\t\t\t\t<div class=\"categories-wrapper\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<span class=\"cat-tag\">Blog<\/span>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<a class=\"cat-tag\" data-cat-level=\"3\" data-destination=\"https:\/\/flex.com\/industries\/data-center?subcategories=data-center-power#resources\" href=\"https:\/\/flex.com\/industries\/data-center?subcategories=data-center-power#resources\">Data Center Power<\/a>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<a class=\"cat-tag\" data-cat-level=\"3\" data-destination=\"\/industries\/industrial?subcategories=power#resources\" href=\"\/industries\/industrial?subcategories=power#resources\">Power<\/a>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<a class=\"cat-tag\" data-cat-level=\"2\" data-destination=\"\/power-modules#resources\" href=\"\/power-modules#resources\">Power Modules<\/a>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t<\/div>\n<\/div>\n\n\n\n<div class=\"sidebar block normal-sidebar\">\n\t<div class=\"container\">\n\t\t<div class=\"content\">\n\t\t\t\n\n<p>The scale of data processing worldwide is staggering, with estimates saying that it now consumes around 1% of global energy production <sup>[1]<\/sup>. This is fueled by ballooning internet use, the IoT and particularly bitcoin mining, which consumes nearly 150 terawatt-hours each year \u2013 more than Sweden does.<\/p>\n\n\n\n<p>All that power is dissipated in server racks and in the AC\/DC and DC\/DC converters that provide power rails, and it has to be removed. Not only has consumption increased but power density has too \u2013 pressure to occupy less space is relentless to improve productivity, and that makes heat extraction doubly difficult. The current best solution is immersion cooling \u2013 submerging the electronics in liquid that carries heat away to a heat exchanger. The technique has been around for many years in demanding applications such as aerospace, but is now becoming attractive in applications that use commercial and industrial-grade components, such as in data centers, EV batteries and drivetrains and in the medical environment. There is a natural concern however about the compatibility of the available fluids with the materials used in mass-produced products such as DC\/DC converters.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"h-immersion-cooling-basics\"><strong>Immersion cooling basics<\/strong><\/h3>\n\n\n\n<p>Immersion cooling follows typically one of two approaches: \u2018single-phase\u2019 where the liquid is circulated by a pump around the electronics and through a heat exchanger to extract the thermal energy, or \u2018two-phase\u2019 where the heat from electronics causes the fluid to effectively \u2018boil\u2019 and cool the hardware through the latent heat of evaporation as well as by conduction and convection. The vapor produced condenses on a heat exchanger and is returned to the pool of liquid. Choice of the liquid used is key, with specific properties required:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Good thermal conductivity to lead heat away <\/li>\n\n\n\n<li>High dielectric strength to withstand circuit voltages<\/li>\n\n\n\n<li>High resistivity to minimise any leakage current <\/li>\n\n\n\n<li>Useful working temperature range<\/li>\n\n\n\n<li>Low environmental impact<\/li>\n\n\n\n<li>Ease of use<\/li>\n\n\n\n<li>Low dielectric constant to avoid excessive increase in capacitance<\/li>\n<\/ul>\n\n\n\n<p>This last parameter is important because any liquid will have a higher dielectric constant than air and this directly and proportionally increases stray capacitances, which can increase electrical losses and even produce unstable operation of any electronics. For example, the dielectric constant of air is close to 1.0 and pure water is around 80. Water is quite a good candidate otherwise but if it turns a negligible 2pF stray capacitance into 160pF, there is likely to be some ill-effect in high-speed circuits. The relatively high freezing point of water is also a potential problem. Use of water is therefore restricted to heat exchangers where the fluid does not contact the electronics directly.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"h-fluid-choices\"><strong>Fluid choices<\/strong><\/h3>\n\n\n\n<p>Suitable fluids have been developed that have more ideal characteristics, and amongst the common types available, they fall into two categories, based on hydrofluoroether (HFE) chemistry, branded as Novec<sup>TM <\/sup>by 3M<sup>TM <\/sup>and on perfluorocarbon (PFC) chemistry, branded as Fluorinert<sup>TM<\/sup>\nby 3M<sup>TM<\/sup>. A summary of some main properties of two popular versions of the liquids is shown below.<\/p>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"\/wp-content\/uploads\/2025\/09\/immers.jpg\" alt=\"Immers\" title=\"\"><\/figure>\n\n\n\n<p>Choice between the two liquids shown depends on the target cooling method; the higher boiling point of Novec<sup>TM<\/sup> 7100 allows single phase immersion cooling at higher temperatures with a low GWP, but applications where dielectric constant, resistivity or dielectric strength are critical might mandate the use of Fluorinert<sup>TM <\/sup>FC72, but with precautions taken to avoid any possible vapor emissions due to its high GWP value. Both materials are promoted as being largely inert but the manufacturer recommends compatibility testing, particularly with Novec<sup>TM<\/sup>, which has a slightly higher solvency characteristic.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Practical compatibility tests<\/strong><\/h3>\n\n\n\n<p>Flex Power Modules undertook to evaluate the two liquids described with advice and guidance from the liquid supplier 3M<sup>TM<\/sup>, with two Flex Power Modules products, the <a href=\"\/products\/bmr490\" target=\"_blank\" rel=\"noreferrer noopener\">BMR490<\/a> and <a href=\"\/products\/bmr491\" target=\"_blank\" rel=\"noreferrer noopener\">BMR491<\/a>. Both are baseplate-cooled quarter-brick DC\/DC converters; the <a href=\"\/products\/bmr490\" target=\"_blank\" rel=\"noreferrer noopener\">BMR490<\/a> is rated at 1300 W with 48 V input and 12 V output and the <a href=\"\/products\/bmr491\" target=\"_blank\" rel=\"noreferrer noopener\">BMR491 <\/a>is similar but can deliver up to 2450 W peak. Test method ASTM G120-15 was used, which defines the \u2018Standard Practice for Determination of Soluble Residual Contamination\u2019. <\/p>\n\n\n\n<p>The DC\/DCs were immersed in flat flasks with a magnetic stirrer set to 75\u00b0C so that both liquids continuously boiled. The standard sets a test duration of less than a day, but Flex Power Modules let the test run for 49 days. During the test, the temperature was increased to 100\u00b0C for several hours to intensify the boiling effect and increase stress.<\/p>\n\n\n\n<p>After the tests, the modules were checked for functionality, inspected, and no overall visual damage was evident. The performance of the silicon-based glue used to fix the transformer and output choke magnetic parts on the module to the PCB was of particular interest and mechanical pressure tests were conducted, to ascertain when the bonds failed. Results showed 402 newtons for the transformer and 144 newtons for the choke, far over the minimum acceptable, so it was concluded that the glue had not been adversely affected in any way.<\/p>\n\n\n\n<p>Close visual inspection of the glue joints followed with no sign of a chemical reaction between the glue and fluid, with good adhesion between the glue, ferrite and PCB (see Figure 1).<\/p>\n\n\n\n<p><\/p>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"\/wp-content\/uploads\/2025\/09\/immers-2.jpg\" alt=\"Immers 2\" title=\"\"><\/figure>\n\n\n\n<p><em>Figure 1: DC\/DC module glue joints after immersion cooling stress tests<\/em><\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Flex Power Modules DC\/DC modules tested are approved for use in immersion cooling applications<\/strong><\/h3>\n\n\n\n<p>The tests performed by Flex Power Modules using the chosen liquids demonstrated clearly that there are no compatibility issues between the module materials and the liquids, even over extended periods at high stress levels. Flex Power Modules is therefore able to say with confidence that their <a href=\"\/products\/bmr490\" target=\"_blank\" rel=\"noreferrer noopener\">BMR490 <\/a>and <a href=\"\/products\/bmr491\" target=\"_blank\" rel=\"noreferrer noopener\">BMR491 <\/a>modules can be used with Novec<sup>TM<\/sup> 7100 and Fluorinert<sup>TM<\/sup>\nFC72 liquids in immersion cooling applications. It is expected that similar Flex Power Modules products and similar liquids will also be compatible if tested.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Note<\/strong><\/h3>\n\n\n\n<p>Since this post was written, 3M have <a href=\"https:\/\/news.3m.com\/2022-12-20-3M-to-Exit-PFAS-Manufacturing-by-the-End-of-2025\" target=\"_blank\" rel=\"noreferrer noopener nofollow\">announced <\/a>that they will discontinue both Novec and Fluorinert coolants by the end of 2025 due to the presence of so called &#8220;forever chemicals&#8221; &#8211; per- and polyfluoroalkyl substances (PFASs). Flex Power Modules are currently investigating alternative cooling liquids that do not contain these substances.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>References<\/strong><\/h3>\n\n\n\n<p><sup>[1]<\/sup> https:\/\/energyinnovation.org\/2020\/03\/17\/how-much-energy-do-data-centers-really-use\/<\/p>\n\n\n\t\t<\/div>\n\t\t<div class=\"sidebar normal-column\">\n\t\t\t\t\t\t\t\t\t<div class=\"post\">\n\t\t\t\t\t\t\t\t<a title=\"Flex Power Modules selection guide\" class=\"image\" href=\"\/downloads\/selection-guide-2026\" target=\"_self\">\n\t\t\t\t\t\t\t\t\t\t<img decoding=\"async\" alt=\"DC\/DC Power modules selection guide\" src=\"https:\/\/flex.com\/wp-content\/uploads\/2025\/02\/DCDC-power-modules-selection-guide-540x304.jpg\" title=\"\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"label\">\n\t\t\t\t\t\t\tBrochure\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t<a title=\"Flex Power Modules selection guide\" class=\"title\" href=\"\/downloads\/selection-guide-2026\" target=\"_self\">\n\t\t\t\t\tFlex Power Modules selection guide\t\t\t\t<\/a>\n\t\t\t<\/div>\n\t\t\t\t\t\t<div class=\"post\">\n\t\t\t\t\t\t\t\t<a title=\"DC\/DC converters for artificial intelligence and machine learning applications\" class=\"image\" href=\"\/downloads\/dc-dc-converters-for-artificial-intelligence-and-machine-learning-applications\" target=\"_self\">\n\t\t\t\t\t\t\t\t\t\t<img decoding=\"async\" alt=\"DC\/DC converters for AI and ML applications\" src=\"https:\/\/flex.com\/wp-content\/uploads\/2025\/09\/DC-DC-converts-ai-applications-540x304.webp\" title=\"\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"label\">\n\t\t\t\t\t\t\tBrochure\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t<a title=\"DC\/DC converters for artificial intelligence and machine learning applications\" class=\"title\" href=\"\/downloads\/dc-dc-converters-for-artificial-intelligence-and-machine-learning-applications\" target=\"_self\">\n\t\t\t\t\tDC\/DC converters for artificial intelligence and machine learning applications\t\t\t\t<\/a>\n\t\t\t<\/div>\n\t\t\t\t\t\t<div class=\"post\">\n\t\t\t\t\t\t\t\t<a title=\"Critical power solutions for reliable, energy-efficient grid-to-rack delivery\" class=\"image\" href=\"https:\/\/flex.com\/zh\/resources\/flex-critical-power-solutions\" target=\"_self\">\n\t\t\t\t\t\t\t\t\t\t<img decoding=\"async\" alt=\"Anord Mardix employee working on critical power products\" src=\"https:\/\/flex.com\/wp-content\/uploads\/2025\/10\/anord-critical-power-540x304.jpg\" title=\"\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"label\">\n\t\t\t\t\t\t\tSolution Brief\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t<a title=\"Critical power solutions for reliable, energy-efficient grid-to-rack delivery\" class=\"title\" href=\"https:\/\/flex.com\/zh\/resources\/flex-critical-power-solutions\" target=\"_self\">\n\t\t\t\t\tCritical power solutions for reliable, energy-efficient grid-to-rack delivery\t\t\t\t<\/a>\n\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t<\/div>\n<\/div>\n\n<div class=\"spacer block\" style=\"height: 72px;\">\n\t<\/div>","protected":false},"excerpt":{"rendered":"<p>\u6d78\u6ca1\u5f0f\u51b7\u5374\u6280\u672f\u5df2\u5728\u4e25\u82db\u7684\u5e94\u7528\u9886\u57df\u5e94\u7528\u591a\u5e74\uff0c\u5982\u4eca\u5728\u5546\u4e1a\u548c\u5de5\u4e1a\u5e94\u7528\u4e2d\u4e5f\u8d8a\u6765\u8d8a\u53d7\u6b22\u8fce\u3002\u4eba\u4eec\u81ea\u7136\u4f1a\u5173\u6ce8\u73b0\u6709\u51b7\u5374\u6db2\u4e0e\u6279\u91cf\u751f\u4ea7\u4ea7\u54c1\uff08\u4f8b\u5982\u76f4\u6d41\/\u76f4\u6d41\u8f6c\u6362\u5668\uff09\u4e2d\u6240\u7528\u6750\u6599\u7684\u517c\u5bb9\u6027\u3002.<\/p>","protected":false},"author":18,"featured_media":5048,"template":"","categories":[90,43,97],"tags":[115],"content-type":[13],"class_list":["post-39034","resource","type-resource","status-publish","has-post-thumbnail","hentry","category-data-center-power","category-power","category-power-modules","tag-bmr491","content-type-blog"],"acf":[],"_links":{"self":[{"href":"https:\/\/flex.com\/zh\/wp-json\/wp\/v2\/resource\/39034","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/flex.com\/zh\/wp-json\/wp\/v2\/resource"}],"about":[{"href":"https:\/\/flex.com\/zh\/wp-json\/wp\/v2\/types\/resource"}],"author":[{"embeddable":true,"href":"https:\/\/flex.com\/zh\/wp-json\/wp\/v2\/users\/18"}],"version-history":[{"count":1,"href":"https:\/\/flex.com\/zh\/wp-json\/wp\/v2\/resource\/39034\/revisions"}],"predecessor-version":[{"id":39399,"href":"https:\/\/flex.com\/zh\/wp-json\/wp\/v2\/resource\/39034\/revisions\/39399"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/flex.com\/zh\/wp-json\/wp\/v2\/media\/5048"}],"wp:attachment":[{"href":"https:\/\/flex.com\/zh\/wp-json\/wp\/v2\/media?parent=39034"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/flex.com\/zh\/wp-json\/wp\/v2\/categories?post=39034"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/flex.com\/zh\/wp-json\/wp\/v2\/tags?post=39034"},{"taxonomy":"content-type","embeddable":true,"href":"https:\/\/flex.com\/zh\/wp-json\/wp\/v2\/content-type?post=39034"}],"curies":[{"name":"\u53ef\u6e7f\u6027\u7c89\u5242","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}