{"id":5932,"date":"2026-07-17T08:47:00","date_gmt":"2026-07-17T00:47:00","guid":{"rendered":"https:\/\/www.topfastpcb.com\/?p=5932"},"modified":"2026-06-25T15:27:42","modified_gmt":"2026-06-25T07:27:42","slug":"dk-and-df-values-in-pcb-materials","status":"publish","type":"post","link":"https:\/\/www.topfastpcb.com\/fi\/blog\/dk-and-df-values-in-pcb-materials\/","title":{"rendered":"PCB-materiaalien Dk- ja Df-arvot"},"content":{"rendered":"<p>Piirilevyjen materiaaleja arvioitaessa l\u00e4hes jokaisessa laminaatin tuotetiedotteessa mainitaan kaksi parametria: dielektrisyysvakio (Dk) ja h\u00e4vi\u00f6kerroin (Df). N\u00e4m\u00e4 arvot vaikuttavat signaalin etenemiseen, impedanssin hallintaan, inserttih\u00e4vi\u00f6\u00f6n sek\u00e4 piirin yleiseen suorituskykyyn.<\/p><p>Hidasnopeuksisessa elektroniikassa Dk- ja Df-arvojen pienill\u00e4 vaihteluilla ei v\u00e4ltt\u00e4m\u00e4tt\u00e4 ole merkitt\u00e4v\u00e4\u00e4 vaikutusta. Nykyaikaisissa tietoliikennej\u00e4rjestelmiss\u00e4, nopeissa digitaalisissa tuotteissa, radiotaajuuspiireiss\u00e4 ja datakeskuslaitteissa materiaalien ominaisuuksien merkitys kasvaa kuitenkin jatkuvasti.<\/p><p>Kun insin\u00f6\u00f6rit ymm\u00e4rt\u00e4v\u00e4t, mit\u00e4 Dk ja Df tarkoittavat, he voivat valita sopivia materiaaleja ja v\u00e4ltt\u00e4\u00e4 signaalin eheyteen liittyvi\u00e4 ongelmia suunnitteluprosessin my\u00f6hemmiss\u00e4 vaiheissa.<\/p><div class=\"wp-block-image\"><figure class=\"aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"600\" height=\"350\" src=\"https:\/\/www.topfastpcb.com\/wp-content\/uploads\/2026\/06\/Dk-and-Df-Values.jpg\" alt=\"Dk- ja Df-arvot\" class=\"wp-image-5933\" srcset=\"https:\/\/www.topfastpcb.com\/wp-content\/uploads\/2026\/06\/Dk-and-Df-Values.jpg 600w, https:\/\/www.topfastpcb.com\/wp-content\/uploads\/2026\/06\/Dk-and-Df-Values-300x175.jpg 300w, https:\/\/www.topfastpcb.com\/wp-content\/uploads\/2026\/06\/Dk-and-Df-Values-18x12.jpg 18w\" sizes=\"auto, (max-width: 600px) 100vw, 600px\" \/><\/figure><\/div><div id=\"ez-toc-container\" class=\"ez-toc-v2_0_74 counter-hierarchy ez-toc-counter ez-toc-custom ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Sis\u00e4llysluettelo<\/p>\n<span class=\"ez-toc-title-toggle\"><\/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.topfastpcb.com\/fi\/blog\/dk-and-df-values-in-pcb-materials\/#What_Is_Dielectric_Constant_Dk\" >Mik\u00e4 on dielektrisyysvakio (Dk)?<\/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.topfastpcb.com\/fi\/blog\/dk-and-df-values-in-pcb-materials\/#What_Is_Dissipation_Factor_Df\" >Mik\u00e4 on h\u00e4vi\u00f6kerroin (Df)?<\/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.topfastpcb.com\/fi\/blog\/dk-and-df-values-in-pcb-materials\/#Why_Dk_Matters_in_PCB_Design\" >Miksi Dk on t\u00e4rke\u00e4 tekij\u00e4 piirilevyjen suunnittelussa<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/www.topfastpcb.com\/fi\/blog\/dk-and-df-values-in-pcb-materials\/#Impedance_Control\" >Impedanssin s\u00e4\u00e4t\u00f6<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/www.topfastpcb.com\/fi\/blog\/dk-and-df-values-in-pcb-materials\/#Signal_Propagation_Delay\" >Signaalin etenemisviive<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/www.topfastpcb.com\/fi\/blog\/dk-and-df-values-in-pcb-materials\/#RF_Circuit_Performance\" >RF-piirin suorituskyky<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/www.topfastpcb.com\/fi\/blog\/dk-and-df-values-in-pcb-materials\/#Why_Df_Matters_in_High-Speed_Design\" >Miksi Df on t\u00e4rke\u00e4\u00e4 suurinopeuksisessa suunnittelussa<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/www.topfastpcb.com\/fi\/blog\/dk-and-df-values-in-pcb-materials\/#Signal_Loss\" >Signaalin menetys<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/www.topfastpcb.com\/fi\/blog\/dk-and-df-values-in-pcb-materials\/#Eye_Diagram_Performance\" >Silm\u00e4kaavion suorituskyky<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/www.topfastpcb.com\/fi\/blog\/dk-and-df-values-in-pcb-materials\/#Longer_Routing_Distances\" >Pidemm\u00e4t reittimatkat<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/www.topfastpcb.com\/fi\/blog\/dk-and-df-values-in-pcb-materials\/#Dk_and_Df_are_frequency-dependent\" >Dk ja Df ovat taajuudesta riippuvia<\/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.topfastpcb.com\/fi\/blog\/dk-and-df-values-in-pcb-materials\/#Typical_Material_Categories\" >Tyypilliset materiaaliluokat<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-13\" href=\"https:\/\/www.topfastpcb.com\/fi\/blog\/dk-and-df-values-in-pcb-materials\/#Standard_FR4\" >Standardi FR4<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-14\" href=\"https:\/\/www.topfastpcb.com\/fi\/blog\/dk-and-df-values-in-pcb-materials\/#High_TG_FR4\" >Korkean lasittumisl\u00e4mp\u00f6tilan FR4<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-15\" href=\"https:\/\/www.topfastpcb.com\/fi\/blog\/dk-and-df-values-in-pcb-materials\/#Low-Loss_Materials\" >V\u00e4h\u00e4h\u00e4vi\u00f6iset materiaalit<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-16\" href=\"https:\/\/www.topfastpcb.com\/fi\/blog\/dk-and-df-values-in-pcb-materials\/#RF_and_Microwave_Materials\" >RF- ja mikroaaltomateriaalit<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-17\" href=\"https:\/\/www.topfastpcb.com\/fi\/blog\/dk-and-df-values-in-pcb-materials\/#Material_Selection_Considerations\" >Materiaalin valintaan liittyvi\u00e4 n\u00e4k\u00f6kohtia<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-18\" href=\"https:\/\/www.topfastpcb.com\/fi\/blog\/dk-and-df-values-in-pcb-materials\/#Common_Engineering_Misconceptions\" >Yleisi\u00e4 v\u00e4\u00e4rink\u00e4sityksi\u00e4 tekniikan alalla<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-19\" href=\"https:\/\/www.topfastpcb.com\/fi\/blog\/dk-and-df-values-in-pcb-materials\/#Lower_Dk_Is_Always_Better\" >Mit\u00e4 pienempi Dk-arvo, sit\u00e4 parempi<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-20\" href=\"https:\/\/www.topfastpcb.com\/fi\/blog\/dk-and-df-values-in-pcb-materials\/#Df_Only_Matters_in_RF_Design\" >Df on merkityksellinen vain RF-suunnittelussa<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-21\" href=\"https:\/\/www.topfastpcb.com\/fi\/blog\/dk-and-df-values-in-pcb-materials\/#All_FR4_Materials_Have_the_Same_Dk_and_Df\" >Kaikilla FR4-materiaaleilla on sama Dk- ja Df-arvo<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-22\" href=\"https:\/\/www.topfastpcb.com\/fi\/blog\/dk-and-df-values-in-pcb-materials\/#FAQ\" >FAQ<\/a><\/li><\/ul><\/nav><\/div>\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"What_Is_Dielectric_Constant_Dk\"><\/span>Mik\u00e4 on dielektrisyysvakio (Dk)?<span class=\"ez-toc-section-end\"><\/span><\/h2><p>Dielektrisyysvakio, jota usein lyhennet\u00e4\u00e4n merkinn\u00e4ll\u00e4 Dk, kuvaa sit\u00e4, miten eristemateriaali varastoi s\u00e4hk\u00f6energiaa.<\/p><p>Piirilevyjen suunnittelussa Dk m\u00e4\u00e4ritt\u00e4\u00e4, kuinka nopeasti signaalit kulkevat dielektrisen materiaalin l\u00e4pi.<\/p><p>Pienempi Dk-arvo johtaa yleens\u00e4 seuraaviin seurauksiin:<\/p><ul class=\"wp-block-list\"><li>Nopeampi signaalin eteneminen<\/li>\n\n<li>Signaalin viiveen lyhent\u00e4minen<\/li>\n\n<li>Pienempi loiskapasitanssi<\/li><\/ul><p>Korkeampi Dk-arvo johtaa tyypillisesti seuraaviin seikkoihin:<\/p><ul class=\"wp-block-list\"><li>Hitaampi signaalinopeus<\/li>\n\n<li>Kapasitanssin kasvu<\/li>\n\n<li>Kompaktimmat RF-rakenteet<\/li><\/ul><p>Jokaisella laminaattimateriaalilla on oma dielektrisyysvakioalueensa.<\/p><p>Tyypillisi\u00e4 arvoja ovat:<\/p><figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><th>Materiaali<\/th><th>Tyypillinen Dk<\/th><\/tr><tr><td>FR4<\/td><td>4,2 \u2013 4,8<\/td><\/tr><tr><td>Korkean lasittumisl\u00e4mp\u00f6tilan FR4<\/td><td>4.1 \u2013 4.7<\/td><\/tr><tr><td>Rogers 4350B<\/td><td>3.48<\/td><\/tr><tr><td>PTFE-materiaalit<\/td><td>2.1 \u2013 2.6<\/td><\/tr><tr><td>Megtron 6<\/td><td>3,3 \u2013 3,5<\/td><\/tr><\/tbody><\/table><\/figure><p>Kuten on k\u00e4sitelty <strong><a href=\"https:\/\/www.topfastpcb.com\/fi\/blog\/fr4-pcb-material\/\">FR4-piirilevyjen materiaali selitettyn\u00e4<\/a><\/strong>, tavallinen FR4 sopii edelleen useimpiin yleisk\u00e4ytt\u00f6isiin elektroniikkasovelluksiin, vaikka sen Dk-arvo onkin korkeampi kuin monilla korkeataajuusmateriaaleilla.<\/p><h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"What_Is_Dissipation_Factor_Df\"><\/span>Mik\u00e4 on h\u00e4vi\u00f6kerroin (Df)?<span class=\"ez-toc-section-end\"><\/span><\/h2><p>H\u00e4vi\u00f6kerroin mittaa, kuinka paljon s\u00e4hk\u00f6energiaa menetet\u00e4\u00e4n l\u00e4mm\u00f6n\u00e4, kun signaalit kulkevat dielektrisen materiaalin l\u00e4pi.<\/p><p>Sit\u00e4 kutsutaan toisinaan:<\/p><ul class=\"wp-block-list\"><li>Tappiotangentti<\/li>\n\n<li>Tan \u03b4<\/li>\n\n<li>Dielektrinen h\u00e4vi\u00f6<\/li><\/ul><p>Pienemm\u00e4t Df-arvot tarkoittavat pienemp\u00e4\u00e4 signaalin h\u00e4vi\u00f6t\u00e4.<\/p><p>Suuremmat Df-arvot johtavat seuraaviin seurauksiin:<\/p><ul class=\"wp-block-list\"><li>Suurempi liit\u00e4nt\u00e4h\u00e4vi\u00f6<\/li>\n\n<li>Heikentynyt signaalin laatu<\/li>\n\n<li>Lyhyemm\u00e4t siirtomatkat<\/li><\/ul><p>Tyypillisi\u00e4 Df-arvoja ovat muun muassa:<\/p><figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><td>Materiaali<\/td><td>Tyypillinen Df<\/td><\/tr><tr><td>FR4<\/td><td>0,015 \u2013 0,025<\/td><\/tr><tr><td>Korkean lasittumisl\u00e4mp\u00f6tilan FR4<\/td><td>0,012 \u2013 0,020<\/td><\/tr><tr><td>Rogers 4350B<\/td><td>0.0037<\/td><\/tr><tr><td>PTFE-materiaalit<\/td><td>0,0009 \u2013 0,002<\/td><\/tr><tr><td>Megtron 6<\/td><td>0.002<\/td><\/tr><\/tbody><\/table><\/figure><p>Tiedonsiirtonopeuksien kasvaessa Df:n merkitys kasvaa usein Dk:ta suuremmaksi.<\/p><h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Why_Dk_Matters_in_PCB_Design\"><\/span>Miksi Dk on t\u00e4rke\u00e4 tekij\u00e4 piirilevyjen suunnittelussa<span class=\"ez-toc-section-end\"><\/span><\/h2><h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Impedance_Control\"><\/span>Impedanssin s\u00e4\u00e4t\u00f6<span class=\"ez-toc-section-end\"><\/span><\/h3><p>Impedanssin s\u00e4\u00e4telyyn perustuvat rakenteet ovat suuresti riippuvaisia dielektrisyysvakioarvoista.<\/p><p>Dk:n muutokset vaikuttavat suoraan:<\/p><ul class=\"wp-block-list\"><li>Johdon leveyden laskeminen<\/li>\n\n<li>Differentiaaliparin suunnittelu<\/li>\n\n<li>Siirtojohtojen k\u00e4ytt\u00e4ytyminen<\/li><\/ul><p>Jopa pienet Dk-vaihtelut voivat muuttaa kohdeimpedanssia.<\/p><p>T\u00e4st\u00e4 syyst\u00e4 kerrostuksen suunnittelussa tulisi aina ottaa huomioon laminaattivalmistajan toimittamat todelliset materiaalitiedot.<\/p><p>Dielektristen ominaisuuksien ja kerrosten v\u00e4lisen et\u00e4isyyden v\u00e4list\u00e4 suhdetta k\u00e4sitell\u00e4\u00e4n my\u00f6s teoksessa <strong><a href=\"https:\/\/www.topfastpcb.com\/fi\/blog\/pcb-core-and-prepreg\/\">PCB-ydin- ja prepreg-materiaalit<\/a><\/strong>.<\/p><h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Signal_Propagation_Delay\"><\/span>Signaalin etenemisviive<span class=\"ez-toc-section-end\"><\/span><\/h3><p>Signaalin etenemisnopeus riippuu dielektrisyysvakiosta.<\/p><p>Materiaalit, joiden Dk-arvo on pienempi, mahdollistavat signaalien nopeamman kulun piirilevyn l\u00e4pi.<\/p><p>T\u00e4m\u00e4 on yh\u00e4 t\u00e4rke\u00e4mp\u00e4\u00e4 seuraavissa tilanteissa:<\/p><ul class=\"wp-block-list\"><li>Nopeat verkot<\/li>\n\n<li>Teko\u00e4lypalvelimet<\/li>\n\n<li>Tietokeskuksen laitteet<\/li>\n\n<li>Takalevyj\u00e4rjestelm\u00e4t<\/li><\/ul><h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"RF_Circuit_Performance\"><\/span>RF-piirin suorituskyky<span class=\"ez-toc-section-end\"><\/span><\/h3><p>RF-insin\u00f6\u00f6rit valitsevat materiaaleja usein osittain niiden Dk-arvon vakauden perusteella eri taajuusalueilla.<\/p><p>Vakaa dielektrinen k\u00e4ytt\u00e4ytyminen paranee:<\/p><ul class=\"wp-block-list\"><li>Antennin suorituskyky<\/li>\n\n<li>Suodattimen suunnittelu<\/li>\n\n<li>Vaihejohdonmukaisuus<\/li>\n\n<li>RF:n toistettavuus<\/li><\/ul><div class=\"wp-block-image\"><figure class=\"aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"600\" height=\"318\" src=\"https:\/\/www.topfastpcb.com\/wp-content\/uploads\/2026\/06\/Dk-and-Df-Values-1.jpg\" alt=\"Dk- ja Df-arvot\" class=\"wp-image-5934\" srcset=\"https:\/\/www.topfastpcb.com\/wp-content\/uploads\/2026\/06\/Dk-and-Df-Values-1.jpg 600w, https:\/\/www.topfastpcb.com\/wp-content\/uploads\/2026\/06\/Dk-and-Df-Values-1-300x159.jpg 300w, https:\/\/www.topfastpcb.com\/wp-content\/uploads\/2026\/06\/Dk-and-Df-Values-1-18x10.jpg 18w\" sizes=\"auto, (max-width: 600px) 100vw, 600px\" \/><\/figure><\/div><h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Why_Df_Matters_in_High-Speed_Design\"><\/span>Miksi Df on t\u00e4rke\u00e4\u00e4 suurinopeuksisessa suunnittelussa<span class=\"ez-toc-section-end\"><\/span><\/h2><p>Alhaisemmilla taajuuksilla dielektriset h\u00e4vi\u00f6t ovat usein merkityksett\u00f6mi\u00e4.<\/p><p>Taajuuden kasvaessa Df:st\u00e4 tulee kuitenkin keskeinen suunnittelun\u00e4k\u00f6kohde.<\/p><h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Signal_Loss\"><\/span>Signaalin menetys<span class=\"ez-toc-section-end\"><\/span><\/h3><p>Suuri Df-arvo aiheuttaa suuremman vaimennuksen pitkill\u00e4 siirtoreiteill\u00e4.<\/p><p>T\u00e4m\u00e4 voi aiheuttaa ongelmia seuraavissa tilanteissa:<\/p><ul class=\"wp-block-list\"><li>25G-verkot<\/li>\n\n<li>56G PAM4 -j\u00e4rjestelm\u00e4t<\/li>\n\n<li>112G-takalevyt<\/li>\n\n<li>Nopeat tallennuslaitteet<\/li><\/ul><h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Eye_Diagram_Performance\"><\/span>Silm\u00e4kaavion suorituskyky<span class=\"ez-toc-section-end\"><\/span><\/h3><p>V\u00e4h\u00e4h\u00e4vi\u00f6iset materiaalit auttavat s\u00e4ilytt\u00e4m\u00e4\u00e4n signaalin aaltomuodot puhtaampina.<\/p><p>Etuihin kuuluvat:<\/p><ul class=\"wp-block-list\"><li>Pienempi v\u00e4rin\u00e4<\/li>\n\n<li>Avaa silm\u00e4t paremmin<\/li>\n\n<li>Parannettu signaalin eheysN\/OFF)<\/li><\/ul><h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Longer_Routing_Distances\"><\/span>Pidemm\u00e4t reittimatkat<span class=\"ez-toc-section-end\"><\/span><\/h3><p>V\u00e4h\u00e4h\u00e4vi\u00f6isten materiaalien ansiosta suunnittelijat voivat reititt\u00e4\u00e4 suurinopeuksisia signaaleja pidemmille et\u00e4isyyksille ilman, ett\u00e4 tarvitaan liiallista tasoitusta.<\/p><h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Dk_and_Df_are_frequency-dependent\"><\/span>Dk ja Df ovat taajuudesta riippuvia<span class=\"ez-toc-section-end\"><\/span><\/h2><p>Yksi yleinen virhe on olettaa, ett\u00e4 Dk ja Df ovat kiinteit\u00e4 arvoja.<\/p><p>Todellisuudessa molemmat suureet vaihtelevat seuraavien tekij\u00f6iden mukaan:<\/p><ul class=\"wp-block-list\"><li>Taajuus<\/li>\n\n<li>L\u00e4mp\u00f6tila<\/li>\n\n<li>Hartsikoostumus<\/li>\n\n<li>Testausmenetelm\u00e4t<\/li><\/ul><p>Esimerkiksi materiaalissa voi olla:<\/p><ul class=\"wp-block-list\"><li>Dk mitattuna taajuudella 1 GHz<\/li>\n\n<li>Dk mitattuna taajuudella 10 GHz<\/li>\n\n<li>Dk mitattu eri testimenetelmill\u00e4<\/li><\/ul><p>Insin\u00f6\u00f6rien tulisi aina tarkistaa materiaalin tuotetiedotteessa mainitut mittausolosuhteet.<\/p><h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Typical_Material_Categories\"><\/span>Tyypilliset materiaaliluokat<span class=\"ez-toc-section-end\"><\/span><\/h2><h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Standard_FR4\"><\/span>Standardi FR4<span class=\"ez-toc-section-end\"><\/span><\/h3><p>Sopii:<\/p><ul class=\"wp-block-list\"><li>Viihde-elektroniikka<\/li>\n\n<li>Teollisuuden ohjauslaitteet<\/li>\n\n<li>Yleisk\u00e4ytt\u00f6iset piirilevyt<\/li><\/ul><p>Edut:<\/p><ul class=\"wp-block-list\"><li>Kustannustehokas<\/li>\n\n<li>Laajasti saatavilla<\/li>\n\n<li>Kehittynyt valmistusprosessi<\/li><\/ul><h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"High_TG_FR4\"><\/span>Korkean lasittumisl\u00e4mp\u00f6tilan FR4<span class=\"ez-toc-section-end\"><\/span><\/h3><p>Valitaan usein seuraaviin tarkoituksiin:<\/p><ul class=\"wp-block-list\"><li>Autoelektroniikka<\/li>\n\n<li>S\u00e4hk\u00f6j\u00e4rjestelm\u00e4t<\/li>\n\n<li>Palvelinten emolevyt<\/li><\/ul><p>Suurin etu on parantunut l\u00e4mp\u00f6luotettavuus eik\u00e4 niink\u00e4\u00e4n dramaattisesti pienentyneet dielektriset h\u00e4vi\u00f6t.<\/p><p>Lis\u00e4tietoja on osoitteessa <strong><a href=\"https:\/\/www.topfastpcb.com\/fi\/blog\/high-tg-fr4-pcb\/\">Korkean TG-arvon FR4-piirilevy<\/a><\/strong>.<\/p><h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Low-Loss_Materials\"><\/span>V\u00e4h\u00e4h\u00e4vi\u00f6iset materiaalit<span class=\"ez-toc-section-end\"><\/span><\/h3><p>Suunniteltu:<\/p><ul class=\"wp-block-list\"><li>Verkkolaitteet<\/li>\n\n<li>Tietokeskuksen laitteisto<\/li>\n\n<li>Teko\u00e4lylaskenta-alustat<\/li><\/ul><p>N\u00e4iss\u00e4 materiaaleissa kustannukset ja signaalin suorituskyky ovat tasapainossa.<\/p><h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"RF_and_Microwave_Materials\"><\/span>RF- ja mikroaaltomateriaalit<span class=\"ez-toc-section-end\"><\/span><\/h3><p>Esimerkkej\u00e4 ovat:<\/p><ul class=\"wp-block-list\"><li>Rogersin laminaatit<\/li>\n\n<li>PTFE-pohjaiset materiaalit<\/li>\n\n<li>Taconic-materiaalit<\/li><\/ul><p>N\u00e4iss\u00e4 j\u00e4rjestelmiss\u00e4 on eritt\u00e4in pieni dielektrinen h\u00e4vi\u00f6 ja erinomainen korkeataajuusvakaus.<\/p><h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Material_Selection_Considerations\"><\/span>Materiaalin valintaan liittyvi\u00e4 n\u00e4k\u00f6kohtia<span class=\"ez-toc-section-end\"><\/span><\/h2><p>Piirilevyjen materiaaleja valittaessa Dk- ja Df-arvoja ei tule arvioida erikseen.<\/p><p>Muita tekij\u00f6it\u00e4 ovat:<\/p><ul class=\"wp-block-list\"><li>Toimintataajuus<\/li>\n\n<li>L\u00e4mp\u00f6vaatimukset<\/li>\n\n<li>Tuotantokapasiteetti<\/li>\n\n<li>Kustannustavoitteet<\/li>\n\n<li>Luotettavuusodotukset<\/li><\/ul><p>Kuten selitet\u00e4\u00e4n kohdassa <strong><a href=\"https:\/\/www.topfastpcb.com\/fi\/blog\/pcb-laminate-materials\/\">PCB-laminaattimateriaalien selitys<\/a><\/strong>, materiaalin valinta on aina kompromissi s\u00e4hk\u00f6isten ominaisuuksien ja k\u00e4yt\u00e4nn\u00f6n valmistusn\u00e4k\u00f6kohtien v\u00e4lill\u00e4.<\/p><p>Paras materiaali ei v\u00e4ltt\u00e4m\u00e4tt\u00e4 ole se, jolla on pienin Df-arvo. Se on materiaali, joka t\u00e4ytt\u00e4\u00e4 projektin vaatimukset ja samalla takaa kohtuulliset kustannukset sek\u00e4 tuotannon luotettavuuden.<\/p><h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Common_Engineering_Misconceptions\"><\/span>Yleisi\u00e4 v\u00e4\u00e4rink\u00e4sityksi\u00e4 tekniikan alalla<span class=\"ez-toc-section-end\"><\/span><\/h2><h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Lower_Dk_Is_Always_Better\"><\/span>Mit\u00e4 pienempi Dk-arvo, sit\u00e4 parempi<span class=\"ez-toc-section-end\"><\/span><\/h3><p>Ei v\u00e4ltt\u00e4m\u00e4tt\u00e4.<\/p><p>Monet piirisuunnitelmat toimivat erinomaisesti FR4-materiaaleilla.<\/p><p>Alhaisemman Dk-arvon omaavat materiaalit ovat edullisia vain silloin, kun s\u00e4hk\u00f6iset vaatimukset oikeuttavat lis\u00e4kustannukset.<\/p><h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Df_Only_Matters_in_RF_Design\"><\/span>Df on merkityksellinen vain RF-suunnittelussa<span class=\"ez-toc-section-end\"><\/span><\/h3><p>Nykyaikaisissa nopeissa digitaalisissa j\u00e4rjestelmiss\u00e4 esiintyy usein samoja signaalih\u00e4vi\u00f6ongelmia kuin radiotaajuuspiireiss\u00e4.<\/p><p>Df on nyky\u00e4\u00e4n keskeinen tekij\u00e4 monissa digitaalisissa sovelluksissa.<\/p><h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"All_FR4_Materials_Have_the_Same_Dk_and_Df\"><\/span>Kaikilla FR4-materiaaleilla on sama Dk- ja Df-arvo<span class=\"ez-toc-section-end\"><\/span><\/h3><p>Eri valmistajien ja hartsij\u00e4rjestelmien dielektriset ominaisuudet voivat vaihdella huomattavasti.<\/p><p>Tarkista aina kyseisen materiaalin tuotetiedot sen sijaan, ett\u00e4 luottaisit yleisiin arvoihin.<\/p><div class=\"wp-block-image\"><figure class=\"aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"600\" height=\"334\" src=\"https:\/\/www.topfastpcb.com\/wp-content\/uploads\/2026\/06\/Dk-and-Df-Values-2.jpg\" alt=\"Dk- ja Df-arvot\" class=\"wp-image-5935\" srcset=\"https:\/\/www.topfastpcb.com\/wp-content\/uploads\/2026\/06\/Dk-and-Df-Values-2.jpg 600w, https:\/\/www.topfastpcb.com\/wp-content\/uploads\/2026\/06\/Dk-and-Df-Values-2-300x167.jpg 300w, https:\/\/www.topfastpcb.com\/wp-content\/uploads\/2026\/06\/Dk-and-Df-Values-2-18x10.jpg 18w\" sizes=\"auto, (max-width: 600px) 100vw, 600px\" \/><\/figure><\/div><h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"FAQ\"><\/span>FAQ<span class=\"ez-toc-section-end\"><\/span><\/h2><div class=\"schema-faq wp-block-yoast-faq-block\"><div class=\"schema-faq-section\" id=\"faq-question-1782366823894\"><strong class=\"schema-faq-question\">K: Mit\u00e4 Dk tarkoittaa piirilevyjen materiaaleissa?<\/strong> <p class=\"schema-faq-answer\">A: Dk on materiaalin dielektrisyysvakio. Se vaikuttaa signaalin etenemisnopeuteen, impedanssiin ja kapasitanssiin.<\/p> <\/div> <div class=\"schema-faq-section\" id=\"faq-question-1782366885560\"><strong class=\"schema-faq-question\">K: Mit\u00e4 Df tarkoittaa piirilevyjen materiaaleissa?<\/strong> <p class=\"schema-faq-answer\">A: Df on h\u00e4vi\u00f6kerroin, joka mittaa dielektrist\u00e4 h\u00e4vi\u00f6t\u00e4 ja ilmaisee, kuinka suuri osa signaalin energiasta muuttuu l\u00e4mm\u00f6ksi.<\/p> <\/div> <div class=\"schema-faq-section\" id=\"faq-question-1782366895721\"><strong class=\"schema-faq-question\">K: Kumpi on t\u00e4rke\u00e4mp\u00e4\u00e4, Dk vai Df?<\/strong> <p class=\"schema-faq-answer\">A: Molemmat ovat t\u00e4rkeit\u00e4, mutta Df on usein ratkaiseva tekij\u00e4 suurinopeuksisissa ja suurtaajuuksisissa sovelluksissa, koska se vaikuttaa suoraan signaalin h\u00e4vi\u00f6\u00f6n.<\/p> <\/div> <div class=\"schema-faq-section\" id=\"faq-question-1782366907089\"><strong class=\"schema-faq-question\">K: Onko FR4:n Df-arvo korkea?<\/strong> <p class=\"schema-faq-answer\">A: Erikoistuneisiin RF-materiaaleihin verrattuna FR4:n Df-arvo on suhteellisen korkea, mik\u00e4 voi rajoittaa suorituskyky\u00e4 eritt\u00e4in korkeilla taajuuksilla.<\/p> <\/div> <div class=\"schema-faq-section\" id=\"faq-question-1782366959550\"><strong class=\"schema-faq-question\">K: Miksi RF-materiaalien Df-arvot ovat pienempi\u00e4?<\/strong> <p class=\"schema-faq-answer\">A: RF-materiaalit on suunniteltu minimoimaan dielektriset h\u00e4vi\u00f6t, mik\u00e4 auttaa s\u00e4ilytt\u00e4m\u00e4\u00e4n signaalin laadun korkeataajuisilla siirtoreiteill\u00e4.<\/p> <\/div> <\/div><p><\/p>","protected":false},"excerpt":{"rendered":"<p>Dielektrisyysvakio (Dk) ja h\u00e4vi\u00f6kerroin (Df) ovat kaksi t\u00e4rkeint\u00e4 parametria piirilevyjen materiaalin valinnassa. Ne vaikuttavat signaalin nopeuteen, impedanssin hallintaan, liit\u00e4nt\u00e4h\u00e4vi\u00f6\u00f6n ja piirin yleiseen suorituskykyyn. Ymm\u00e4rt\u00e4m\u00e4ll\u00e4, miten Dk ja Df vaihtelevat FR4-materiaalissa, korkean TG-arvon laminaateissa, Rogers-materiaaleissa, PTFE:ss\u00e4 ja muissa v\u00e4h\u00e4h\u00e4vi\u00f6isiss\u00e4 j\u00e4rjestelmiss\u00e4, insin\u00f6\u00f6rit voivat valita oikean materiaalin suurinopeuksisiin, RF- ja dataviestint\u00e4sovelluksiin.<\/p>","protected":false},"author":1,"featured_media":5936,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[108],"tags":[487,488,484],"class_list":["post-5932","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news","tag-df-values","tag-dk-values","tag-pcb-material"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v25.1 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Dk and Df Values in PCB Materials<\/title>\n<meta name=\"description\" content=\"Dk and Df values in PCB materials, how 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