Dynamic Compact Thermal Model Development within ROHM Semiconductor
约翰威尔森Technical Marketing Engineer,Mentor Graphics and Ippei Yasutake,Senior Engineer,Rohm Co.,Ltd.
It is commonly accepted that two of the trends in the electronics industry are miniaturization and the electrification of all things.As a result electronics today are deployed into dynamic and sometimes harsh environments.As the environments have changed,so have the requirements for the system integrators.Today,companies need IC package models that can accurately predict dynamic thermal performance.
Currently there is no standardized methodology for developing a dynamic compact thermal model (DCTM) though there are important elements that exist.At ROHM Semiconductor Co.,Ltd.well established standards and processes have been extended to meet the needs of their customers.They are able to provide validated DCTM models that facilitate more robust designs in a shorter amount of time.ROHM is coordinating with JEIITA to provide a standardized approach to DCTM development.
Measure and Calibrate
The initial step in the process is to accurately measure the transient behavior of the IC device to calibrate a detailed thermal model.来自Mentor Graphics的t3ster®热测试仪和Flotherm®CFD热分析软件，金宝愽备用网址were used to measure and calibrate the thermal model.Figure 1 compares the Structure Function of the measured device with the FloTHERM analysis model.The Structure Function is derived from the transient thermal measurement and represents the thermal resistances and capacitances along the heat flow path.A model calibrated against the Structure Function is valid for any transient scenario.
DELPHI Compact Thermal Model
Though the detailed model provides value to ROHM Semiconductor for internal design processes it doesn't represent the preferred method for use in system level thermal design.Detailed IC models represent a significant computational expense and also expose internal packaging details.The calibrated detailed model was used to develop a DELPHI compact thermal model (CTM).FloTHERM PACK was used to develop the DELPHI model from the calibrated detailed model.Figure 2 shows the DELPHI resistor network of the HTSSOP-B24 with the node locations shown in figure 3.
Modified DELPHI CTM Development
Delphi CTM在环境中进行了测试，并确定用一个节点表示模具不足以捕获模具上存在的局部加热。A modification to the network was made as shown in figure 4.With the additional resistors the accuracy in junction temperature prediction was reduced from 33% to within 1%.
Modified DELPHI DCTM Development
The final step in the development of the DTCM was to add capacitance to nodes within the network.Capacitance was added at the nodes,shown in figure 5,and were based on the physical properties on the detailed IC model.
详细的热模型和改进的Delphi DCTM之间的瞬态响应比较如图6所示。Overall the correlation between the two is quite good with the DCTM Junction temperature matching the detailed model at 2% difference at the end of the transient,or overall thermal resistance.The behavior of the temperature response during the transient is captured by the DCTM as well.
To design electronics for the dynamic world we live in we must understand their dynamic behavior,with the IC component as an integral part.With T3Ster hardware and the Structure Function the transient response of IC packages can be accurately measured which is supported with standards.The development of a DELPHI CTM is outlined through standards,with the first requirement being to start with a validated detailed model.Currently there are no standards regarding the development of a DCTM.Though there is no standard,Rohm Semiconductor实施了一个开发DCTM的过程，使其达到量化精度，使其客户能够在动态世界中进行设计。The process used by ROHM is not only benefiting their customers but also used in a collaboration effort with JEITA to develop a standardized approach to DCTM development.
ROHM Semiconductor is an industry leader in system LSI,分立元件和模块产品，utilizing the latest in semiconductor technology.ROHM's proprietary production system,which includes some of the most advanced automation technology,是保持其在电子元件制造业领先地位的一个主要因素。In addition to its development of electronic components,ROHM has also developed its own production system so that it can focus on specific aspects of customized product development.ROHM employs highly skilled engineers with expertise in all aspects of design,development and production.这使得Rohm能够灵活地进行广泛的应用和项目，并能够为汽车行业的重要客户提供服务，电信和计算机部门，as well as consumer OEMs.