Thermal Analysis of Multilayer Printed Circuit Board using Ansys ICEPAK

Thermal Analysis of Multilayer Printed Circuit Board using Ansys ICEPAK The electric industry market is projectd to grow rapidly as the electricifcation revolution is changing the automobile and aerospace industries.Due to electrification revolution, the electronics components in the system are increasing. The electronics devices are becoming more and more compact but at the same time the functionality of these electronics related components are also increasing. Electronics systems can contain various types of parts such as Motherboard,cpu,ram ,capacitors,fans,heat sinks, grills etc. One of the most important component of any electronics system is its motherboard.Thermal management of Motherboard is a an important factor which designer keep in mind while designing any electronics system. When computer systems performs tasks the data is exchanged between various components and all these data travels through printed circuit board so thermal management of pcb is required to decrease the temperature. Printed circuit board contains copper traces and vias .The simulation of ECAD pcb is very important as copper traces change the metal fraction and the thermal conductivities of pcb resulting in more uniform temperature distribution as compare to the single layered pcb. Geometry modelling in space-claim: Generates polyhedral meshes, polyhedral prisms can easily uphold mesh quality for refined boundary layer regions. Offers wrapping advantage to mesh large assemblies. Parallel mode execution without using any HPC licenses, consistent speed scale-up. Can run with both Solver and Pre-post license. To show the importance of detail modelling of pcb, a generalised elctronics system is designed using Ansys Spaclaim. Please note that this cad design is in no way sponsored by or affiliated with any organization. We can observe that fans,grills and other components are not modelled here,it is because we are going to modelled fans,grills,resistances in the icepak window. The creation of the model is very rapid from assembly level to the board level.Ansys icepak can create fans,heat sinks, grills,tec,heat packages,network and all the sorts of things which are present in any electronics components.After modelling the geometry all the parts are converted into icepak obejects using icepak simplification tool. Modelling Primitive objects in Icepak After importing the spaceclaim file into Ansys Icepak other primitive objects such as fans,grills,resistances,openings are created inside the assembly using model>create option available in the Ansys Icepak window. Complete Assembly Modelling fans Icepak allow you to model fan without using MRF approach also.Here in the simulation fans curves and fan duty cycles are used to model the fans.Operating RPM and swirl RPM are used as inputs. Air filters – Air filters can be modelled as resistance.Resistances are modelled as porous domain in Ansys fluent. Grills – Icepak allows to you to model the grill using pressure loss specification.Pressure loss specification can be given either using opening arear ratio or through pressure velocity curve data. ECAD Printed circuit board : Ecad files are imported on to the pcb board. Icepak can read ecad files of various formats such as ODB++,Ansys EDB, Ansoft, Gerber etc. Ansys Icepak reads traces and vias and computes the metal fraction map based on the grid density(rows*column).The model layers seperately option should be turn on to ensure proper mesh connection as shown in figure Metal Fraction Mapping and thermal conductivities vaulues calculation: Ansys Icepak computes thermal conductivities values based on the grid density. This thermal conductivity values will be used as input for thermal simulation. Grid density cuts the PCB into various rows and columns and assign thermal conductivities values to each grid. Mapping Thermal metal fraction and thermal conductivity values Effort less meshing using Ansys Icepak Ansys Icepaks’ HD Mesher generates high-quality mesh even for complex geometries. The process of generating the mesh is extremely easy and less time-consuming. Ansys Icepak generates the fluid domain automatically using the cabinet approach and saves a lot of time spent on pre-processing. The overall time required to perform the simulation reduces drastically. Referring to the current case, the overall time spent on meshing and generating high-quality mesh was ~ 15 mins and within 15 mins, 3 mesh trials were performed to identify and optimize assembly size and slack settings. Icepak automatically finds and generates the fluid domain based on empty spaces inside the cabinet/enclosure (with no solid bodies/hollow bodies). Figure 5 and figure 6 shows the mesh created in Ansys Icepak. PCB assembly mesh Assembly meshing Simulation and Post-processing Electronincs Cooling Simulation of System with Ecad PCB Simulation of the system is done after giving necessary inputs/ boundary conditions required for running the simulation, such as heat sources wattage, ambient temperature, radiation parameters and material properties description, etc.Figure 7 shows the temperature distribution of the pcb assembly.The maximum temperature obtained for the pcb is ~ 92˚C. Figure 8 shows the velocity streamlines starting from the fan. Figure 9 shows the thermal conductivity distribution of the top layer of the pcb. PCB assembly temperature distribution Velocity Streamlines PCB thermal conductivity distrbution Electronics Cooling Simulation of System with Ecad PCB A second iteration is performed by removing the ECAD from the pcb to know the significance of ecad modelling on the pcb temperature distribution.Figure 10 shows the temperature distribution of the pcb assembly. By removing the ecad from the pcb,thermal conductivity of the pcb became 0.34 W/m- K(Fr4) and this led to a very siginificant rise in the temperature of the heat sources.We can also see due to low conductivity,hot spots are getting formed.The maximum temperature location is also getting changed due to change in thermal conductivity value of board at maximum temperature location for second iteration.Table 1 shows the difference between the maximum temperature obtained from the simulation with the without ECAD pcb.The difference in temperature shows the importance of detailed ECAD PCB modelling and simulaion. PCB temperature distribution without ECAD PCB Modelling Maximum Temperatures Average Thermal Conductivity of PCB Board PCB with Traces and Vias 92 ˚C Inplane = 35W/m-K,Normal = 7.08 W/m-K PCB without Traces and vias 258 ˚C Inplane = 0.34 W/m-K,Normal = 0.34 W/m-K Comparison Table Conclusion: The present work was an attempt to demonstrate Ansys Icepak’s capabilities in reading and simulating

Thermal Simulation of Automotive Lamps Using Ansys ICEPAK

Lighting Systems play an important role in human factors of safe driving. It is an essential part of any vehicle and has undergone significant changes and advances in lighting technology over the years. Thermal aspects play a crucial role when it comes to the designing of automotive lights. Automotive lighting systems mainly consist of outer lens, inner lens, housing, reflectors, bulb, bezel, Led, PCB and light guide, etc.. Automotive headlamp Out of the parts mentioned above, bulb and led are the two primary sources of lighting that generate a lot of heat energy. Hence it is essential to design the automobile lamps such that even at an extreme ambient temperature, the temperature on each part is maintained well below the critical limit. The critical limit is usually the heat deflection temperature & the maximum temperature on the parts of the lighting system should be well below their respective material HDT values. The role of CFD simulation in Automotive lamp designing? Generates polyhedral meshes, polyhedral prisms can easily uphold mesh quality for refined boundary layer regions. Offers wrapping advantage to mesh large assemblies. Parallel mode execution without using any HPC licenses, consistent speed scale-up. Can run with both Solver and Pre-post license. Coming to the main question – “What is the role of Computational Fluid Dynamics and software tools such as Ansys in designing the automotive lighting system”? CFD simulations can play a crucial role in optimizing various design parameters such as lamp size, the distance between bulb and lens, number of vents, vent location, and selection of materials according to the design requirements. The thermal simulation of automotive lamps comes under conjugate heat transfer type of analysis in which all the modes of heat transfer are essential to model. Radiation is the key source of heat transfer in lamps. Radiation affects the heat wattage from the filament or led source chip and increases the following – temperature of the bulb, reflector, housing, lens, etc. Hence, proper selection of the radiation model is important to get accurate results. Since many parts are interlinked, thermal conduction plays a crucial role in heat distribution especially when automotive lighting systems contain Led chips and PCB. As all three modes of heat transfer are involved in this simulation, various parameters are needed to benchmark to get the correct results. There are mostly three kinds of simulation done for Automotive lamps as follows: Simulation of Headlamps: The bulb of the headlamp consists of two filaments called High beam and Low beam filament. The Low beam filament is situated closer towards the lens and the High beam filament is placed closer towards the bulb holder. Generally, analysis of the former is more preferred than high beam one because when the Low beam filament is switched ON, the lamp parts get more heated. However, some companies also tend to perform analysis by turning ON both high beam and low beam filaments to predict the maximum temperature in the worst-case scenario. Simulation of Taillamp: Tail lamps are generally smaller in size as compared to headlamps, so to avoid high temperatures, they should be carefully designed. Tail lamps consist of tail function filament and stop function filament. Tail lamp simulation is done by turning ON both the tail function and stop function filament. Simulation of Front turning lamp: Headlamp consists of a signal turning bulb. Sometimes companies prefer to simulate the headlamps along with the front turning lamp. Often, two turning signal bulbs will be at the sides of headlamps. These two signal lamps may contain separate reflector parts and lens parts. The wattage of these bulbs is generally small, but as these signal bulbs are cramped to a smaller area, it may end up heating the lens and reflector way above HDT values. That is why engineers very often perform simulations for these lamps as well. Table 1: Lamp Main parts and material description: Parts Most Preferred Material Heat deflection temperature range Outer Lens Plastics 100°C -140°C Housing PMMA 90°C-120°C Reflector PMMA/Plastics 90°C-120°C Bulb Glass N. A Bezel Plastics/PET+PBT 90°C -140°C Inner lens Plastics 100°C -140°C The main aim of the simulation is to predict the temperature distribution in various lamp parts and to find out if the maximum temperature is greater or lesser than the Heat deflection temperature. This can help the design team to select the best material according to the design requirement. The simulation can also help the design team to decide the proper locations of air vents by predicting the air-flow path and location of maximum temperature. Advantages of using Ansys Icepak in Automotive light thermal simulation: Ansys Icepak is the most popular tool in the market when it comes to electronics cooling simulation. It uses Fluent as a solver which is one of the most reliable and popular solvers when it comes to CFD. The top advantage of using Ansys Icepak is that it saves us from the tedious task of generating fluid domain. It can automatically generate fluid domain using a cabinet or enclosure approach and creates hexahedral mesh easily. Using Icepak we can save a lot of time which we spend in generating fluid domain and creating a high-quality mesh. Moreover, Ansys Icepak has various radiation models, such as S2S, DO, Ray, tracing models which can be used both for participating and non-participating mediums accordingly. To show the capability of Ansys Icepak in simulating automotive lighting systems, a quite simple model of an Automotive headlamp is developed using Spaceclaim. Please note that this cad design is in no way sponsored by or affiliated with any organization. Lamp without lens Vents Bulb Outer lens Lamp Parts Icepak Simplification: The Spaceclaim objects will be converted into icepack objects using the Icepak simplification feature available in Spaceclaim. Conversion to icepack objects is necessary and every geometry part must be converted to icepack objects through icepack simplification in space claim or design modeler. Conversion of Spaceclaim parts to Icepak objects Mesh created in Icepak Effort less meshing using Ansys Icepak: Ansys Icepaks’ HD Mesher generates