Search Results

Modern automobiles are dependent on complex networks of electronic sensors and controls for efficient and safe operation. These electronic modules are tested for stringent environmental load conditions where product validation consists of one or a combination of loads such as Vibration, Mechanical Shock, Temperature, Water, Humidity, Dust, Chemicals, and Radiation. Exposure of electronics to water leads to many harmful effects resulting in the failure of electronic systems. Previously published technical paper [1] SAE 2023-01-0157 described a methodology to estimate risk in a humid environment, where water is dispersed in air as a gas phase. The present paper extends the scope of virtual validation using Computational Fluid Dynamics (CFD) simulation tools to an environment with water in the liquid phase. In this paper, a non-sealed automotive electronic module subjected to a water drip test is evaluated using the CFD model.

In modern automobiles a complex network of electronic sensors and controls is being integrated for increased comfort, convenience, and safety. All of these needs to be designed for the stringent environmental condition requirements. Environmental tests used for validation of product primarily consists of combination of Vibration load, Temperature and Humidity. Failures induced by vibration Load and temperature cycling are fairly well understood and often simulation can help design team to understand weakness in design and evaluate design options to mitigate it. However, Humidity and temperature (cyclic or constant) are critical as well referred as Climatic tests. The purpose of climatic tests are to assess the ability of a product to operate reliably under condensing conditions. Unlike other environmental test where there are visual clues of something broken, these test could lead to failure without any visual clues.

The electronic content in automotive has increased over recent years and expected to contribute about 50% of the total vehicle cost by 2030. The semiconductor research indicates that focus is on enhancing the functionality of single device and miniaturizing of components to reduce the electronic module size. It is to be ensured, that devices in automotive electronic modules should be within its allowable temperature limit while operating at harsh environment. The accurate virtual simulations using CAE tools prior to proto build can assist in understanding the design risks upfront and aids in arriving at a reliable thermal mitigation solution. The prediction accuracy of thermal simulation is driven by the inputs and modeling approach used in the analysis. Current automotive electronic product development trend indicates, chip development and thermal design of electronics module goes in parallel.

Current generation automobiles are controlled by electronic modules for performing various functions. These electronic modules have numerous semiconductor devices mounted on printed circuit boards. Solders are generally used as thermal interface material between surface mount devices and printed circuit boards (PCB) for efficient heat transfer. In the manufacturing stage, voids are formed in solders during reflow process due to outgassing phenomenon. The presence of these voids in solder for power packages with exposed pads impedes heat flow and can increase the device temperature. Therefore it is imperative to understand the effect of solder voids on thermal characteristics of semiconductor devices. But the solder void pattern will vary drastically during mass manufacturing. Replicating the exact solder void pattern and doing detail simulation to predict the device temperature for each manufactured module is not practical.

Automotive Electronic Control Unit (ECU) has semiconductor devices performing various time dependent functions. It is essential to understand the transient thermal behavior of these devices for designing a reliable system. Detailed thermal model (DTM) is the need of the hour to understand the characteristics by performing a transient system level simulation. The information to build DTM is not readily available in the public domain due to intellectual property protection from the device suppliers. To overcome this, the present work showcases the procedure to develop Transient Thermal Network Model (TTNM) using resistance and capacitance values extracted from the impedance curve provided by the semiconductor manufacturer. TTNM model is developed for a typical DPAK and D2PAK device and validated by comparing impedance curve derived from simulation with datasheet.