{"id":419,"date":"2012-10-28T10:20:07","date_gmt":"2012-10-28T15:20:07","guid":{"rendered":"http:\/\/tonykordyban.com\/?page_id=419"},"modified":"2014-04-13T20:27:59","modified_gmt":"2014-04-14T01:27:59","slug":"everything-you-know-is-wrong-november-2002","status":"publish","type":"page","link":"http:\/\/tonykordyban.com\/?page_id=419","title":{"rendered":"Everything You Know Is Wrong   November 2002"},"content":{"rendered":"<p><strong>Answers to those Doggone Thermal Design Questions<\/strong><\/p>\n<p><strong>By Tony Kordyban<\/strong><\/p>\n<p align=\"right\">Copyright by Tony Kordyban 2002<\/p>\n<p><em>Dear Mr. Everything Wrong,<\/em><\/p>\n<p><em>I have heard your criticism of the use of Theta j-a, the so-called thermal resistance from junction to ambient.\u00a0 You argue that it is not good for estimating the junction temperature of a component, for a variety of reasons, and I agree with you.\u00a0 But what about that other thermal resistance, Theta j-c, the resistance between the junction and the case?\u00a0 Is that number more accurate, or at least, more useful than Theta j-a?\u00a0 Can I use it to estimate the junction temperature of a component after I have measured the case temperature (assuming that I know the power dissipation)?<\/em><\/p>\n<p><em>I thought that Theta j-c should be better for two reasons:<\/em><\/p>\n<p><em>1.\u00a0 Unlike for Theta j-a, I know where to\u00a0 measure the case temperature, but the &#8220;ambient&#8221; air temperature referenced by Theta j-a is not defined.<\/em><\/p>\n<p><em>2.\u00a0 Theta j-c is the conductive resistance inside the package, which depends only on the materials from which it is made, so it doesn&#8217;t change.<\/em><\/p>\n<p><em>I am hoping that even if Theta j-c is not totally accurate, it will at least be conservative.\u00a0 By conservative I mean that it will give me an estimate of junction temperature that is never lower than the actual junction temperature.\u00a0 If there is error, it should estimate too high, so that I don&#8217;t approve a component for use, and then have it fail thermally in the field.<\/em><\/p>\n<p><em>Can you help me understand Theta j-c better?<\/em><\/p>\n<p><em>Buffaloed in up-stateNew York<\/em><\/p>\n<p>&nbsp;<\/p>\n<p>Dear Buff,<\/p>\n<p>Here is the short answer to your question:<\/p>\n<ul>\n<li>Theta j-c is not any better at estimating junction temperature than Theta j-a.<\/li>\n<li>Theta j-c is not just a function of the construction and materials of the component package.\u00a0 It also depends on the Printed Circuit Board (PCB) to which it is soldered, among other factors, so it will change from application to application.<\/li>\n<li>Theta j-c is not guaranteed to give you a conservative estimate of junction temperature.\u00a0 In some cases it will give you a junction temperature estimate lower than the actual value.<\/li>\n<\/ul>\n<p>Don&#8217;t you feel better already?<\/p>\n<p>Let&#8217;s define what you really need, and then let&#8217;s define Theta j-c, so we can see how they are not the same thing.<\/p>\n<p>What you want:\u00a0 It is simple to attach a thermocouple to the surface of a component.\u00a0 That is pretty close, but not quite close enough to the temperature we all lust after &#8212; the temperature of the chip itself (also called the die or junction.)\u00a0 How much hotter is the chip than the case (the outside surface of the component package)?\u00a0 Naturally that depends on the heat dissipated by the chip.\u00a0 It would be nice if there were some characteristic number for any component package, that could tells us the temperature difference between the chip and the case, assuming we know the power of the chip.\u00a0 The formula for that might look like this:<\/p>\n<p style=\"padding-left: 30px;\"><strong>Tj &#8211; Tc = package characteristic x Power<\/strong><\/p>\n<p>What you get:\u00a0 That was the motive, I suppose, behind the creation of Theta j-c a long time ago.\u00a0 Here is how it is defined:<\/p>\n<p style=\"padding-left: 30px;\"><strong>Theta j-c\u00a0 = (Tj &#8211; Tc) \/ Q<sub>t<\/sub><\/strong><\/p>\n<p>&nbsp;<\/p>\n<table width=\"100%\" border=\"0\" cellspacing=\"0\" cellpadding=\"0\">\n<tbody>\n<tr>\n<td>where<\/td>\n<td>Tj<\/td>\n<td>is the junction temperature<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td>Tc<\/td>\n<td>is the case temperature<\/td>\n<\/tr>\n<tr>\n<td><\/td>\n<td>Q<sub>t<\/sub><\/td>\n<td>is the total heat from the chip<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>It is measured by mounting a component on a standard test board (about 4 in by 5 in).\u00a0 Q<sub>t<\/sub>, Tc and Tj are measured in a special chamber (sometimes in a liquid bath!) and Theta j-c is calculated.\u00a0 This sounds a lot like what you want, because<\/p>\n<p style=\"padding-left: 30px;\"><strong>\u00a0 Tj &#8211; Tc = Theta j-c x\u00a0 Q<sub>t<\/sub><\/strong><\/p>\n<p>Doesn&#8217;t that qualify Theta j-c to be the package characteristic you want?<\/p>\n<p align=\"left\">Well, not exactly.\u00a0 The only situation where this is really valid is shown in Figure 1.<\/p>\n<div id=\"attachment_420\" style=\"width: 413px\" class=\"wp-caption alignleft\"><a href=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/10\/theta_ja.jpg\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-420\" class=\" wp-image-420 \" title=\"theta_ja\" src=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/10\/theta_ja.jpg\" alt=\"\" width=\"403\" height=\"226\" srcset=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/10\/theta_ja.jpg 576w, http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/10\/theta_ja-300x168.jpg 300w\" sizes=\"auto, (max-width: 403px) 100vw, 403px\" \/><\/a><p id=\"caption-attachment-420\" class=\"wp-caption-text\">Figure 1. Theta j-c is a true resistance if the component is always mounted on a perfect insulator.<\/p><\/div>\n<p>If the component is mounted on a perfect insulator, then all the heat flows from the chip to the top of the package.\u00a0 There is only one path for heat to get to the surrounding fluid, and so that path can be characterized by a single resistance, which you could call Theta j-c, if you wanted to.<\/p>\n<div id=\"attachment_421\" style=\"width: 310px\" class=\"wp-caption alignleft\"><a href=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/10\/r_jc_real.jpg\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-421\" class=\"size-medium wp-image-421\" title=\"r_jc_real\" src=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/10\/r_jc_real-300x208.jpg\" alt=\"\" width=\"300\" height=\"208\" srcset=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/10\/r_jc_real-300x208.jpg 300w, http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/10\/r_jc_real.jpg 576w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><p id=\"caption-attachment-421\" class=\"wp-caption-text\">Figure 2. On a PCB, there is more than one path for heat to follow.<\/p><\/div>\n<p>Even if Theta j-c were measured this way, it would not be very useful to you, because you are going to attach the component to a PCB, which is a pretty good heat spreader.\u00a0 And that changes everything.<\/p>\n<p>Package testers have to hook up the leads of their components somehow, too, so they use a PCB when they measure Theta j-c.\u00a0 It looks more like Figure 2.<\/p>\n<p>As soon as you have a PCB, heat flows out of the chip through multiple paths, each with its own thermal resistance.\u00a0 Some heat still flows through the top surface, but lots of heat goes out through the leads, spreads in the PCB, and from there into the surrounding fluid.<\/p>\n<p>To keep our story simple, let&#8217;s say that for our particular component there are only two heat paths &#8212; one up to Tc on the top surface, and the second down to the bottom of the package, where the leads connect to the PCB.\u00a0 I call the temperature at the bottom of the package Tb.\u00a0 If we included all the other heat paths, the argument would be the same, but much more complicated to follow.<\/p>\n<div id=\"attachment_422\" style=\"width: 295px\" class=\"wp-caption alignleft\"><a href=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/10\/network.jpg\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-422\" class=\"size-medium wp-image-422\" title=\"network\" src=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/10\/network-285x300.jpg\" alt=\"\" width=\"285\" height=\"300\" srcset=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/10\/network-285x300.jpg 285w, http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/10\/network.jpg 350w\" sizes=\"auto, (max-width: 285px) 100vw, 285px\" \/><\/a><p id=\"caption-attachment-422\" class=\"wp-caption-text\">Figure 3. Thermal network way of looking at a component package.<\/p><\/div>\n<p>When you have two paths for heat to follow, the total chip heat is going to split up.\u00a0 Some will flow up to Tc, and the rest to Tb.\u00a0 How it splits depends on the relative resistances of the two paths.\u00a0 This kind of problem is usually attacked by drawing a resistor network, like in Figure 3.<\/p>\n<p>I am going to use the letter R as a symbol of a true thermal resistance, which depends only on the dimensions and the material properties of the conduction path.\u00a0 Theta is not really a resistance &#8212; it is intended as a &#8220;figure or merit&#8221; for<br \/>\ncomparing one kind of package against another.<\/p>\n<p>Figure 3 is a resistor network for a component package soldered to a PCB.\u00a0 It has two parallel paths from the chip to the fluid.\u00a0 Below is an explanation of the symbols in the figure.<\/p>\n<p>&nbsp;<\/p>\n<div align=\"center\">\n<table width=\"80%\" border=\"0\" cellspacing=\"0\" cellpadding=\"0\">\n<tbody>\n<tr>\n<td width=\"13%\">Tj<\/td>\n<td width=\"86%\">junction temperature<\/td>\n<\/tr>\n<tr>\n<td width=\"13%\">Q<sub>c<\/sub><\/td>\n<td width=\"86%\">the portion of the total chip heat that travels up through the top of the package<\/td>\n<\/tr>\n<tr>\n<td width=\"13%\">Q<sub>pcb<\/sub><\/td>\n<td width=\"86%\">the portion of the heat that travels through the leads into the PCB<\/td>\n<\/tr>\n<tr>\n<td width=\"13%\">Rj-c<\/td>\n<td width=\"86%\">conduction resistance between the chip and the top of the package.\u00a0 This value is a constant for the package, because it depends only on the dimensions and materials of the package itself<\/td>\n<\/tr>\n<tr>\n<td width=\"13%\">h<\/td>\n<td width=\"86%\">the convective heat transfer coefficient between the solid surfaces and the surrounding fluid<\/td>\n<\/tr>\n<tr>\n<td width=\"13%\">A<sub>c<\/sub><\/td>\n<td width=\"86%\">the surface area of the top of the package.\u00a0 Together with h, it determines the thermal resistance between the case and the fluid, which is not a constant property of the package<\/td>\n<\/tr>\n<tr>\n<td width=\"13%\">Rj-b<\/td>\n<td width=\"86%\">the conduction resistance between the die and the bottom of the package<\/td>\n<\/tr>\n<tr>\n<td width=\"13%\">Rb-pcb<\/td>\n<td width=\"86%\">the spreading resistance from the leads throughout the PCB<\/td>\n<\/tr>\n<tr>\n<td width=\"13%\">A <sub>pcb<\/sub><\/td>\n<td width=\"86%\">the surface area of the PCB (both sides) exposed to the fluid<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p>Even without writing out all the equations for solving this network, you can see that Tj is a function of ALL these variables.\u00a0 Most of them are nearly impossible for somebody like you or me to figure out for any real component on a real PCB.\u00a0 Look at the resistor network in Figure 3 and imagine that you can figure out Tj by just measuring Tc and knowing the total power and Theta j-c.\u00a0 That is equivalent to claiming you can calculate the current in any net in a circuit by measuring the voltage at one node, and knowing the total power and the overall impedance of the circuit.<\/p>\n<p>That is just a &#8220;hand-wavy&#8221; argument.\u00a0 Maybe numerically, Theta j-c is still good enough.\u00a0 So to figure that out I have put together the equations of the network into a <a title=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/10\/theta_jc1.xls\" href=\"file:\/\/\/C:\/Documents%20and%20Settings\/Tony\/My%20Documents\/CoolingZone\/CoolingZone%20Web%20Articles\/2002\/November%202002\/theta_jc.xls\">spreadsheet<\/a>.\u00a0 You can <a title=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/10\/theta_jc1.xls\" href=\"file:\/\/\/C:\/Documents%20and%20Settings\/Tony\/My%20Documents\/CoolingZone\/CoolingZone%20Web%20Articles\/2002\/November%202002\/theta_jc.xls\">download<\/a>\u00a0it and plug numbers into it<\/p>\n<div id=\"attachment_427\" style=\"width: 310px\" class=\"wp-caption alignleft\"><a href=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/10\/spreadsheet1.jpg\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-427\" class=\"size-medium wp-image-427\" title=\"spreadsheet1\" src=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/10\/spreadsheet1-300x206.jpg\" alt=\"\" width=\"300\" height=\"206\" srcset=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/10\/spreadsheet1-300x206.jpg 300w, http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/10\/spreadsheet1.jpg 566w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><p id=\"caption-attachment-427\" class=\"wp-caption-text\">Figure 4. One set of resistance values that lead to a very poor prediction of Tj.<\/p><\/div>\n<p>and see how good a job Theta j-c does at predicting Tj in your application.\u00a0 Here are some examples that I made for illustration.\u00a0 (Don&#8217;t bother clicking on the images of the spreadsheets &#8212; they are just screen captures.\u00a0 To change the values you&#8217;ll have to download the spreadsheet and run it on your machine.)\u00a0 Be aware that I have made up the resistance values out of whole cloth and they don&#8217;t represent any real component package.<\/p>\n<p>One reason Theta j-c is not all that useful is that it is measured under different conditions than you will have in your application.\u00a0 In the Theta j-c test, the component and PCB are submerged in liquid.\u00a0 That&#8217;s why on the left side of the spreadsheet I chose a value for h of 100 W\/m<sup>2<\/sup>C.\u00a0 Your air-cooled PCB has h closer to 20 W\/m<sup>2<\/sup>C.\u00a0 The other big difference is that in the Theta j-c test, the component is all alone on a PCB with a large surface area.\u00a0 Your PCB may be even larger than the test PCB, but your component has to share all that area with bunches of<\/p>\n<div id=\"attachment_429\" style=\"width: 310px\" class=\"wp-caption alignleft\"><a href=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/10\/spreadsheet2.jpg\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-429\" class=\"size-medium wp-image-429\" title=\"spreadsheet2\" src=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/10\/spreadsheet2-300x206.jpg\" alt=\"\" width=\"300\" height=\"206\" srcset=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/10\/spreadsheet2-300x206.jpg 300w, http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/10\/spreadsheet2.jpg 564w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><p id=\"caption-attachment-429\" class=\"wp-caption-text\">Figure 5. Theta j-c can be wrong in any direction.<\/p><\/div>\n<p>other components.\u00a0 So the effective area that can be used by your component to dissipate heat is probably much smaller.<\/p>\n<p>In Figure 4 I made Rj-c much larger than Rj-b, and that leads to a value of Theta j-c that does a very poor job of predicting Tj in a more realistic application.\u00a0 The temperature rise between junction and case is off by over 19 degrees C.\u00a0 And Theta j-c predicts Tj to be lower than it actually is.\u00a0 So at least in theory, Theta j-c is NOT guaranteed to be conservative.<\/p>\n<p>But it is not always wrong in the same direction, as you can see in Figure 5.<\/p>\n<p>In Figure 6 I have added a large heat sink to the top of the component.\u00a0 That is included in the spreadsheet by<\/p>\n<div id=\"attachment_431\" style=\"width: 310px\" class=\"wp-caption alignleft\"><a href=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/10\/spreadsheet3.jpg\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-431\" class=\"size-medium wp-image-431\" title=\"spreadsheet3\" src=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/10\/spreadsheet3-300x236.jpg\" alt=\"\" width=\"300\" height=\"236\" srcset=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/10\/spreadsheet3-300x236.jpg 300w, http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/10\/spreadsheet3.jpg 569w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><p id=\"caption-attachment-431\" class=\"wp-caption-text\">Figure 6. How does Theta j-c do when you add a heat sink?<\/p><\/div>\n<p>changing the surface area of the top (Ac) to a large number.\u00a0 I was a little surprised to see that, at least for this combination of resistances, adding a heat sink magnifies the error that Theta j-c has in estimating Tj.\u00a0 The heat sink causes more heat to flow through the top surface path, increasing the temperature rise between junction and case.\u00a0 The heat sink does reduce Tj, but not as much as you might think if you trusted in Theta j-c.<\/p>\n<p>I don&#8217;t know how realistic my resistance values are.\u00a0 I have not investigated this very thoroughly, but just played around a little to see what happens.\u00a0 I invite you to do the same, especially if you might know some real values you can plug in.\u00a0 But I think I have demonstrated that it is not very hard to find combinations of resistances that make Theta j-c look bad.<\/p>\n<p>After you&#8217;re done playing, you&#8217;ll be convinced that Theta j-c is not an accurate, or even a safe, way to estimate Tj.\u00a0 So how should you find Tj from a measurement of Tc?<\/p>\n<p>I&#8217;m afraid that is an entirely different question, and you only get one question per month.<\/p>\n<p align=\"center\"><strong><a title=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/10\/theta_jc1.xls\" href=\"file:\/\/\/C:\/Documents%20and%20Settings\/Tony\/My%20Documents\/CoolingZone\/CoolingZone%20Web%20Articles\/2002\/November%202002\/theta_jc.xls\">DOWNLOAD THE THETA J-C SPREADSHEET\u00a0<\/a><\/strong><\/p>\n<p>\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014<\/p>\n<p align=\"center\"><strong>Isn\u2019t Everything He Knows Wrong, Too?<\/strong><\/p>\n<p align=\"center\"><em><strong>The straight dope on Tony Kordyban<\/strong><\/em><\/p>\n<p>Tony Kordyban has been an engineer in the field of electronics cooling for different telecom and power supply companies (who can keep track when they change names so frequently?) for the last twenty years.\u00a0 Maybe that doesn\u2019t make him an expert in heat transfer theory, but it has certainly gained him a lot of experience in the ways NOT to\u00a0cool electronics.\u00a0 He does have some book-learnin\u2019, with a BS in Mechanical Engineering from the University of Detroit (motto:Detroit\u2014 no place for wimps) and a Masters in Mechanical Engineering from Stanford (motto: shouldn\u2019t Nobels count more than Rose Bowls?)<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignleft\" title=\"tk_head_shot\" src=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/05\/tk_head_shot-150x150.jpg\" alt=\"\" width=\"150\" height=\"150\" \/>In those twenty years Tony has come to the conclusion that a lot of the common practices of electronics cooling are full of baloney.\u00a0 He has run into so much nonsense in the field that he has found it easier to just assume \u201ceverything you know is wrong\u201d (from the comedy album by Firesign Theatre), and to question everything against the basic principles of heat transfer theory.<\/p>\n<p>Tony has been collecting case studies of the wrong way to cool electronics, using them to educate the cooling masses, applying humor as the sugar to help the medicine go down.\u00a0 These have been published recently by the ASME Press in a book called, \u201cHot Air Rises and Heat Sinks:\u00a0 Everything You Know About Cooling Electronics Is Wrong.\u201d\u00a0 It is available direct from ASME Press at 1-800-843-2763 or at their web site at\u00a0<a title=\"ASME Press\" href=\"http:\/\/www.asme.org\/products\/books\/hot-air-rises-and-heat-sinks---everything-you-know\">http:\/\/www.asme.org\/pubs\/asmepress<\/a><strong><em>,\u00a0\u00a0<\/em><\/strong>Order Number 800741.<\/p>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Answers to those Doggone Thermal Design Questions By Tony Kordyban Copyright by Tony Kordyban 2002 Dear Mr. Everything Wrong, I have heard your criticism of the use of Theta j-a, the so-called thermal resistance from junction to ambient.\u00a0 You argue that it is not good for estimating the junction temperature of a component, for a [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-419","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"http:\/\/tonykordyban.com\/index.php?rest_route=\/wp\/v2\/pages\/419","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/tonykordyban.com\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"http:\/\/tonykordyban.com\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"http:\/\/tonykordyban.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/tonykordyban.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=419"}],"version-history":[{"count":11,"href":"http:\/\/tonykordyban.com\/index.php?rest_route=\/wp\/v2\/pages\/419\/revisions"}],"predecessor-version":[{"id":439,"href":"http:\/\/tonykordyban.com\/index.php?rest_route=\/wp\/v2\/pages\/419\/revisions\/439"}],"wp:attachment":[{"href":"http:\/\/tonykordyban.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=419"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}