The thermal management design of high-power LED modules is a core element to ensure their long-term stability and efficient operation. The following are the design ideas and key technical points of a set of systems:
\nTemperature control: The junction temperature (Tj) should be kept within the range allowed by the device specification, usually below 120\u2103. Because for every 10\u2103 temperature rise, the luminous efficacy will decrease by 3-5% and the lifespan will be halved, it is necessary to strictly avoid the problems of luminous efficacy attenuation and shortened lifespan.
\nUniform temperature performance: The temperature gradient between chips should be minimized as much as possible to prevent the occurrence of local hotspots.
\nThermal path optimization: To achieve efficient heat conduction from the chip to the environment and ensure that heat can be dissipated in a timely manner.
\n2.1 Substrate materials
\nCeramic substrate
\nAl\u2082O\u2083 (aluminum oxide) : It has a relatively low cost, approximately 0.5 to 1 yuan per cm\u00b2, with a thermal conductivity ranging from 24 to 28 W\/(m\u00b7K), making it suitable for medium and low power scenarios.
\nAlN (Aluminum nitride) : Its thermal conductivity can reach 170-230 W\/(m\u00b7K), but it is relatively expensive, costing 3-5 yuan \/cm\u00b2, and is suitable for high power density scenarios. 10 W\/mm\u00b2.
\nMetal substrate (MCPCB) : Taking aluminum substrate as an example, its thermal conductivity is 1-3 W\/(m\u00b7K), and it is used in combination with an insulating layer. Although the cost is relatively low, the thermal resistance of the insulation layer needs to be optimized.
\n2.2 Heat Dissipation Structure
\nPassive heat dissipation
\nFinned heat sink: It mainly relies on natural convection to achieve heat dissipation. Among them, the ratio of fin height to spacing (usually between 5:1 and 10:1) and the surface blackness (which can be enhanced through anodic oxidation treatment to increase the emissivity) are the key factors.
\nHeat pipe\/vapor chamber: Utilizing the principle of phase change heat transfer, its thermal conductivity can reach 5000 W\/(m\u00b7K), making it highly suitable for eliminating local hotspots.
\nActive heat dissipation
\nFan forced convection: The air volume needs to match the air resistance of the radiator. The typical air volume is 0.1-0.5 CFM\/W.
\nLiquid cooling system: Microchannel cold plates (water-cooled) can handle The heat flux density is 100 W\/cm\u00b2, but the entire system is rather complex.
\nThermal grease: The thermal resistance is between 0.1 and 0.5 \u2103\u00b7cm\u00b2\/ W. However, it should be noted that after long-term use, it may age and dry up.
\nPhase change material (PCM) : With a thermal resistance of 0.05-0.2 \u2103\u00b7cm\u00b2\/W, it undergoes phase change at 45-60\u2103, thereby filling the voids.
\nThermal conductive gasket: It belongs to elastic materials, with a hardness ranging from Shore 00 30 to 50. It can compensate for assembly tolerances, and the thermal resistance is between 0.3 and 1.0 \u2103\u00b7cm\u00b2\/W.
\nSimulation tool:
\nThree-dimensional models can be established using ANSYS Icepak or FloTHERM, with a focus on the thermal resistance network (the total thermal resistance \u03b8_ja from the junction to the environment).
\nParametric analysis was conducted on parameters such as fin thickness and spacing to study their influence on the heat transfer coefficient (the natural convection heat transfer coefficient is approximately 5-10 W\/(m\u00b2\u00b7K)).
\nExperimental verification:
\nInfrared thermal imaging: This technology can precisely locate hot spot areas, with a measurement accuracy of \u00b12\u2103.
\nJunction temperature measurement: Calibration was carried out using the forward voltage method (Vf-Tj coefficient approximately -2 mV\/\u2103).
\nDrive current optimization: When Tj > At 85\u2103, the starting current derating measures are implemented, for example, with a reduction of 0.5% per \u2103.
\nOptical matching: By means of secondary optical design, ineffective heat generation is reduced, such as improving the efficiency of the reflector cup. 90%.
\nStructural layout
\nThe multi-chip modules are arranged in an interlaced manner with a spacing of \u22653 mm, thereby reducing mutual thermal coupling.
\nThe power drive circuit is physically isolated from the LED to reduce the superposition of heat sources.
\nAccelerated aging test
\nThe test was conducted for 1000 hours under the condition of 85\u2103\/85%RH, and the light attenuation should be… Five percent.
\nCarry out temperature cycling tests (-40\u2103 to +125\u2103, 100 cycles) to examine the CTE matching of the materials.
\nFailure mode analysis
\nFor the problem of solder joint fatigue (Cokendall vowel), it can be improved by using Sn-Ag-Cu solder.
\nFor the carbonization problem of phosphor, it is necessary to control the surface temperature of the blue light chip. 150\u2103.
\nHierarchical heat dissipation design
\nLow-power segment 50W) : Heat dissipation is achieved through an aluminum substrate combined with natural convection.
\nMedium power range (50-200W) : A heat dissipation solution combining heat pipes and forced air cooling is adopted.
\nHigh power segment (200W) : Consider using liquid cooling or semiconductor refrigeration methods.
\nModular design: Allows for the expansion of heat dissipation capacity in the later stage, such as reserving fan interfaces, etc.
\nSample solution: 200W LED module
\nSubstrate: AlN ceramic is selected, with dimensions of 40mm\u00d740mm and a thickness of 1mm.
\nRadiator: It adopts 6063 aluminum alloy fins, with dimensions of 200mm\u00d7150mm\u00d750mm, and the surface is blackened.
\nTIM: Use graphene to fill the phase change material with a thickness of 0.2mm.
\nThermal resistance: \u03b8_jc = 0.8\u2103\/W, \u03b8_ca = 1.2\u2103\/ W. From this, \u03b8_ja = 2.0\u2103\/W can be obtained.
\nTemperature rise: \u0394T = 200W\u00d72.0\u2103\/W = 40\u2103. When the ambient temperature is 25\u2103, Tj = 65\u2103.
\nThrough multi-physics field collaborative design and full life cycle thermal management, the luminous efficacy of LED modules can be achieved. 150 lm\/W, lifespan 50,000 hours (L70 standard) of industrial-grade performance. The specific parameters still need to be iteratively optimized in combination with optical and electrical designs.<\/p>","protected":false},"excerpt":{"rendered":"
The thermal management design of high-power LED modules is a core element to ensure their long-term stability and efficient operation. […]<\/p>\n","protected":false},"author":2,"featured_media":2571,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"default","adv-header-id-meta":"","stick-header-meta":"default","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"set","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[88],"tags":[],"class_list":["post-2570","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.ihylight.com\/vi\/wp-json\/wp\/v2\/posts\/2570","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ihylight.com\/vi\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ihylight.com\/vi\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ihylight.com\/vi\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ihylight.com\/vi\/wp-json\/wp\/v2\/comments?post=2570"}],"version-history":[{"count":1,"href":"https:\/\/www.ihylight.com\/vi\/wp-json\/wp\/v2\/posts\/2570\/revisions"}],"predecessor-version":[{"id":2572,"href":"https:\/\/www.ihylight.com\/vi\/wp-json\/wp\/v2\/posts\/2570\/revisions\/2572"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.ihylight.com\/vi\/wp-json\/wp\/v2\/media\/2571"}],"wp:attachment":[{"href":"https:\/\/www.ihylight.com\/vi\/wp-json\/wp\/v2\/media?parent=2570"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ihylight.com\/vi\/wp-json\/wp\/v2\/categories?post=2570"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ihylight.com\/vi\/wp-json\/wp\/v2\/tags?post=2570"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}