Alumina is the default ceramic substrate for a reason. It is cheap, strong, and easy to metallize. It is also a poor heat pipe. A 96% Al\u2082O\u2083 board sits around 20\u201330 W\/m\u00b7K. Aluminium nitride, done properly, lands in the 170\u2013200 W\/m\u00b7K range, sometimes a bit over 200. Theory for a perfect single crystal is near 320. Nobody ships that. What we ship is a sintered insulator that can take die heat out of a power module without becoming a conductor.<\/p>\n
That combination is the job. Metals conduct heat and current. Most ceramics block current and trap heat. Aluminum nitride does heat and insulation at the same time, with a CTE around 4.5 ppm\/\u00b0C \u2014 close to silicon. Alumina expands more like 6.5\u20137.5. On a high-power IGBT or SiC device that mismatch shows up as solder fatigue and a peeling copper foil. BeO conducts even better and we still avoid it when we can. Toxicity is not a datasheet footnote.<\/p>\n
Oxygen is the impurity that ruins the conductivity story. Lattice oxygen creates aluminum vacancies. Phonons scatter. Powder with a couple percent oxygen sinters to something that looks like AlN and measures closer to 100 W\/m\u00b7K. Low-oxygen powder plus a sintering aid that pulls oxygen into a grain-boundary phase \u2014 yttria is the usual one \u2014 is how you get the 170-plus grade. Density has to be high. A residual pore is another scattering site. So \u201cAlN substrate\u201d on a PO is not a grade. Ask for thermal conductivity, not just chemistry.<\/p>\n
Powder handling is where shops get surprised. Fine AlN hydrolyzes. Leave it in humid air and you grow a hydroxide skin and raise the oxygen you just paid to remove. Dry storage, short open time, sometimes a surface treatment. That is not fussiness. It is how the k value survives until the kiln.<\/p>\n
We use aluminum nitride where the thermal stack actually needs it: DBC and DPC power boards, RF packages, laser and LED submounts, some semiconductor process parts. If the die is a few watts and the heat sink is the bottleneck, alumina still wins on price. If you are dumping tens of watts through a thin ceramic into copper, the substrate drop on alumina is no longer free. The ceramic costs more. The module that does not throttle or delaminate is the return.<\/p>\n
Machining and metallization need the same honesty. AlN is not as casual as 96% alumina. Edges chip. Copper bonding has to match the expansion. A beautiful 180 W\/m\u00b7K disk with a bad interface is just an expensive insulator. Specify k, thickness, surface, and the metal system together. Aluminium nitride is a heat path that happens to be a ceramic. Treat it that way and it earns the premium. Treat it like white alumina with a better brochure and it will not.<\/p>","protected":false},"excerpt":{"rendered":"
Aluminium Nitride Moves Heat Like a Metal and Still Blocks Current Alumina is the default ceramic substrate for a reason. […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_seopress_robots_primary_cat":"none","_seopress_titles_title":"","_seopress_titles_desc":"","_seopress_robots_index":"","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":"","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-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":"","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-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":"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":""},"mobile":{"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":""}},"footnotes":""},"categories":[2],"tags":[],"class_list":["post-74","post","type-post","status-publish","format-standard","hentry","category-products-related"],"_links":{"self":[{"href":"https:\/\/aluminiumnitride.com\/id\/wp-json\/wp\/v2\/posts\/74","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/aluminiumnitride.com\/id\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/aluminiumnitride.com\/id\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/aluminiumnitride.com\/id\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/aluminiumnitride.com\/id\/wp-json\/wp\/v2\/comments?post=74"}],"version-history":[{"count":1,"href":"https:\/\/aluminiumnitride.com\/id\/wp-json\/wp\/v2\/posts\/74\/revisions"}],"predecessor-version":[{"id":77,"href":"https:\/\/aluminiumnitride.com\/id\/wp-json\/wp\/v2\/posts\/74\/revisions\/77"}],"wp:attachment":[{"href":"https:\/\/aluminiumnitride.com\/id\/wp-json\/wp\/v2\/media?parent=74"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/aluminiumnitride.com\/id\/wp-json\/wp\/v2\/categories?post=74"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/aluminiumnitride.com\/id\/wp-json\/wp\/v2\/tags?post=74"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}