基于模态试验的PCB板结构动态性能的等效建模

Equivalent Modeling of PCB for Dynamic Properties Based on The Modal Test

PCB因其基板内部结构的复杂性以及元器件种类众多且分布无规律性导致有限元模型建立困难,为此本文针对某车载热像仪主处理板上元器件的分布及结构特点,提出了一种基于自由模态试验数据的PCB板动态性能等效建模的方法。该方法对基板采用其原几何尺寸建立,对元器件的处理方式根据其物理属性以及在基板上分布特点按不同方法处理,最终需保持等效模型的质量与实际相等,并利用了自由模态试验数据以及最小二乘法推导出了基板的等效刚度以及泊松比的计算方法。通过正弦扫频试验获取主处理板的响应曲线,利用半功率带宽法计算前两阶响应对应的阻尼比,将阻尼比有限元分析软件中,获得等效模型数值计算的响应曲线,与试验的响应曲线对比,结果表明该等效建模方法满足实际工程需求,为类似产品的等效建模提供了可借鉴的思路。

It is difficult to establish a finite element model for a PCB owing to the complexity of the internal structure of the substrate,the large variety of components,and irregular distribution.To solve these issues,this article proposes the distribution and structural characteristics of the components on the main processing board of a vehicle thermal imaging camera as an equivalent modeling method of PCB board dynamic performance based on free modal test data.This method uses the original geometric size of the substrate and the components are processed in different ways according to their physical properties and distribution characteristics on the substrate.Finally,the quality of the equivalent model must be kept equal to the actual model,and the free mode is used.The experimental data and least square method were used to deduce the equivalent stiffness of the substrate and the calculation of Poisson's ratio,respectively.The response curve of the main processing board was obtained through a sine frequency sweep test.The damping ratio corresponding to the first two-order responses was calculated using the half-power bandwidth method,and the damping ratio finite element analysis software was used to obtain the response curve of the equivalent model numerical calculation.A comparison of the response curves shows that the equivalent modeling method meets the actual engineering requirements and provides a reference for the equivalent modeling of similar products.