{"id":313889,"date":"2023-10-30T08:17:40","date_gmt":"2023-10-30T08:17:40","guid":{"rendered":"\/forum\/forums\/reply\/313889\/"},"modified":"2023-10-30T08:17:40","modified_gmt":"2023-10-30T08:17:40","slug":"313889","status":"publish","type":"reply","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/313889\/","title":{"rendered":"Reply To: Multilayer PCB modal analysis first mode natural frequency related."},"content":{"rendered":"<p>&lt;p&gt;@ Erik&lt;\/p&gt;&lt;p&gt;<strong>&#8221; Also how well do you know the material properties (you certain of all the properties &ndash; often there is a variation) &ndash; sometimes we need to alter\/change them a bit to get better agreement with test data.&#8221;<\/strong>&lt;\/p&gt;&lt;p&gt;Sir&lt;\/p&gt;&lt;p&gt;Your question is valid , I am using FR4 properties given in Ansys Mechanical while this PCB board is made from Isola 370HR (FR4) dielectric material. For this i don&#8217;t have all the 9 properties values required for an orthotropic material.&lt;\/p&gt;&lt;p&gt;From datasheet of Isola 370HR , i got few properties which are as below:&lt;\/p&gt;&lt;p&gt;E1 (along length direction) : 3744 ksi ( ~ 25814 MPa)&lt;\/p&gt;&lt;p&gt;E2 (along cross direction ) : 3178 ksi (~ 21912 MPa)&lt;\/p&gt;&lt;p&gt;<a href=\"https:\/\/www.isola-group.com\/wp-content\/uploads\/sites\/2\/data-sheets\/370hr.pdf\">https:\/\/www.isola-group.com\/wp-content\/uploads\/sites\/2\/data-sheets\/370hr.pdf<\/a>&lt;\/p&gt;&lt;p&gt;Poisson&#8217;s Ratio :&lt;\/p&gt;&lt;p&gt;A. Length direction : 0.177&lt;br&gt;B. Cross direction&nbsp; &nbsp;: 0.171&lt;\/p&gt;&lt;p&gt;The other properties details are missing like E3 , Vz , G12 , G13 &amp; G23.&lt;\/p&gt;&lt;p&gt;Since , these properties are not available , i have rely on FR4 properties given in Ansys Mechanical. Here, also i observed that for shear modulus calculation formula used is valid for isotropic material.&lt;\/p&gt;&lt;p&gt;like Ex : 20.4 GPa&lt;\/p&gt;&lt;p&gt;vxy : 0.11&nbsp;&lt;\/p&gt;&lt;p&gt;if you see the Gxy value it is 9200 MPa which will come from G = E\/ (2*(1+v)).&lt;\/p&gt;&lt;p&gt;I don&#8217;t have exact material properties , that may be one of the reason that modal frequency is not matching.&lt;\/p&gt;&lt;p&gt;Please suggest if you came across this material or having mechanical properties.&lt;\/p&gt;&lt;p&gt;&nbsp;&lt;\/p&gt;&lt;p&gt;&nbsp;&lt;\/p&gt;&lt;p&gt;&nbsp;&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-313889","reply","type-reply","status-publish","hentry"],"aioseo_notices":[],"acf":[],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/replies\/313889","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/replies"}],"about":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/types\/reply"}],"version-history":[{"count":0,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/replies\/313889\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=313889"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}