PTC封装结构热管理模拟研究

Thermal Management Simulation of PTC Package Structure

PTC发热元件因其恒温发热能力和安全性逐渐取代传统金属发热元件,在汽车空调等领域拥有广阔的应用前景。但用于PTC发热元件封装结构的硅胶粘剂热导率极低,导致封装结构散热能力较差,元件工作温度高,这会对元件功率和寿命产生不利影响。因此,对PTC发热元件封装结构进行热管理研究有着很强的必要性。利用COMSOL Multiphysics模拟仿真软件对PTC封装结构进行了热管理模拟计算,通过不同参数下结构温度分布研究了BaTiO3陶瓷分布阵列、胶层厚度、胶体热导率和冷却条件对PTC封装结构散热能力的影响。模拟结果显示,BaTiO3陶瓷3×3分布阵列相比于9×1阵列而言,可使PTC封装结构具有更高的散热能力;胶体热导率越高、胶层厚度越小、冷却液流速越快、封装结构散热能力越强,而冷却液温度对封装结构散热无明显影响。最后结合理论分析,提出了提高封装散射结构的新方案,即将BaTiO3陶瓷9×1分布阵列改为3×3阵列,使用更高热导率的硅胶,减小胶层厚度,提高冷却液流速。新方案可提高封装结构散热能力,进而提高发热元件功率和寿命。

Positive Temperature Coefficient(PTC)heating components are taking the place of the traditional metal ones because of their safety and ability to work steadily on a constant temperature and have a broad application prospect in automotive air conditioning and other fields.However,as the adhesive commonly used in PTC heating components packaging,organic silicon adhesive has a very low thermal conductivity coefficient,which leads to poor heat dissipation capability of package structure.It also adversely affects the power and life of heating components,so the research on thermal management of PTC heating components package structure is necessary.In this paper,the temperature distribution was simulated based on COMSOL Multiphysics,a simulation software,and the influence on heat dissipation capability of various factors were researched.By comparing temperature distribution graph,the influence of different BaTiO3 arrays,the thickness of adhesive,the thermal conductivity coefficient of adhesive and cooling conditions on heat dissipation capability of PTC heating components package structure were researched.The results showed that compared with 9×1 array,3×3 array could improve the heat dissipation capability.Besides,higher thermal conductivity and lower thickness of adhesive and faster flow rate of cooling liquid were also profitable to heating dissipation while the temperature of cooling liquid has no significant influence on heat dissipation.Combined with theory analysis,solutions were proposed to improve heat dissipation capability of PTC heating components package structure.The BaTiO3 ceramic 9×1 array is replaced by a 3×3 array,and adhesive with higher thermal conductivity is used,the thickness of the adhesive is reduced and the flow rate of the cooling liquid is reduced.The new scheme can improve the heat dissipation capacity of the package structure,thus increasing the power and lifetime of the heating element.