Modeling of thermal via heat transfer performance for power electronics cooling

Thermal Modeling and Design Optimization of PCB Vias and Pads

Abstract: Miniature power semiconductor devices mounted on printed circuit boards (PCBs) are normally cooled by means of PCB vias, copper pads, and/or heatsinks. Various reference PCB thermal designs have been provided by semiconductor manufacturers and researchers. However, the recommendations are not optimal, and there are some discrepancies among them, which may confuse electrical engineers. This paper aims to develop analytical thermal resistance models for PCB vias and pads, and further to obtain the optimal design for thermal resistance minimization. First, the PCB via array is thermally modeled in terms of multiple design parameters. A systematic parametric analysis leads to an optimal trajectory for the via diameter at different PCB specifications. Then, an axisymmetric thermal resistance model is developed for PCB thermal pads where the heat conduction, convection, and radiation all exist; due to the interdependence between the conductive/radiative heat transfer coefficients and the board temperatures, an algorithm is proposed to fast obtain the board-ambient thermal resistance and to predict the semiconductor junction temperature. Finally, the proposed thermal models and design optimization algorithms are verified by computational fluid dynamics simulations and experimental measurements.

A review of thermal management in power converters with thermal vias

Abstract: One important challenge in power electronics design is removing the heat cost effectively from the power devices. A thermal via is a small diameter hole plated with copper and is used to transfer the heat from one side of the printed circuit board (PCB) to the other side. In this paper, a thorough literature review of the design and analysis of thermal vias in PCBs for thermal management of devices in power electronics converters are presented. Key advantages of using PCB's for thermal management are also presented. Based on the conclusions drawn from the available literature and practical manufacturing guidelines, four different via patterns for a single power device are selected and their thermal performances are studied. Each of the four via patterns is laid out multiple times on the same PCB. A power component in a D2PAK is soldered to each of the patterns. The PCB is attached to a liquid cooled cold plate. The devices are powered up and a thermal imaging camera is used to record the temperature of the device. The experimental results presented closely matches with the theoretical prediction and helps in identifying the most efficient thermal via pattern.

Performance comparison of thermal interface materials for power electronics applications

Abstract: One important challenge in power electronics design is removing the heat cost effectively from the power devices mounted on thermal vias on a printed circuited board (PCB). Thermal vias is a cluster of small diameter hole plated with copper and is used to transfer the heat from one side of the PCB where the power device is soldered to the other side which is generally mounted on a heat sink using a thermal interface material (TIM). To minimize the contact resistance and provide electrical insulation between the PCB and heat sink, TIMs are used to fill the air gaps and are an essential part of an assembly when solid surfaces are attached together. This paper presents a detailed comparison of the properties of various off-the-shelf available TIMs to be specifically used between PCB with thermal vias and heat sink. Experimental results are presented to determine the thermal performance of various TIMs.

A comparison of thermal vias patterns used for thermal management in power converter

Abstract: A daunting challenge in packaging design for power electronics products is removing the heat from the power devices in a cost effective manner In this paper, a thorough literature review of the design and analysis of thermal vias in PCBs for thermal management of power electronics devices are presented Based on the results from the available literature and practical manufacturing guidelines, four different via patterns for single power devices are selected Each of the four via patterns is laid out multiple times with their via holes are filled with a filler material and their performance are compared to non-filled thermal vias One dimensional analysis is performed to characterize the thermal performance of the thermal via patterns The experimental results presented closely matches the theoretical prediction to identify the most efficient thermal via pattern

Copper Coin Over Thermal VIA in PCB for Thermal Management of 12W

Abstract: This work developed a copper (Cu) coin structure embedded on a printed circuit board (PCB) to dissipate a 12 W peak power out of the device system working at less than 60 °C. The designed Cu coin was based on the manufacturing limitations and allowed the thermal setup to be mounted on the bottom side of the board for automated test equipment (ATE) applications of the device. Thermal simulations through computational fluid dynamics (CFD) were analyzed and presented both for Cu coin and thermal vertical interconnect access (VIA), to quantify the thermal performances and compare the thermal benefits. Size variations on the designed Cu coin were investigated and quantified setting a thermal decay rate per change in dimension. The actual thermal measurement for the fabricated Cu coin design was presented on the experimental results, matching the simulation values and proving the viability of thermal Cu coin.

Cooling techniques for electronic equipment

Abstract: Evaluating the Cooling Requirements. Designing the Electronic Chassis. Conduction Cooling for Chassis and Circuit Boards. Mounting and Cooling Techniques for Electronic Components. Practical Guides for Natural Convection and Radiation Cooling. Forced--Air Cooling for Electronics. Thermal Stresses in Lead Wires, Solder Joints, and Plated Throughholes. Predicting the Fatigue Life in Thermal Cycling and Vibration Environment. Transient Cooling for Electronic Systems. Special Applications for Tough Cooling Jobs. Effective Cooling for Large Racks and Cabinets. Finite Element Methods for Mathematical Modeling. Environmental Stress Screening Techniques. References. Index.

Thermal characterization of vias using compact models

Abstract: Thermal vias and balls are key elements in plastic ball grid array (PBGA) package thermal design as they enhance the package performance. Simulation is a versatile design optimization tool for characterizing the thermal vias and balls. However, the finer geometric details of the vias require excessive memory and modeling and simulation time. Different modeling concepts are being tried in the industry to include finer geometries in the package. This paper shows a methodology of developing compact thermal via models and validating the same with detailed models. The accuracy of compact thermal via models with respect to the detailed models has been determined using PBGA 352 as the test vehicle. It is found that the accuracy is within 3%. The simulation models of PBGA 352 have been validated by measurements and found that the accuracy of model is within 10%. Two and four layer PBGA 352s with different via configurations have been characterized with compact thermal via models, and design guidelines for PBGA 352 packages have been obtained.

Analysis on thermal resistance of LED module with various thermal vias

Abstract: Light Emitting Diode (LED) has been already familiar that is used as lighting sources of general electronic devices and various displays. LED has many advantages such as long life, low power consumption and high reliability. In the future, as alternative to fluorescent lighting, it is sure that LED in lighting products is expected to receive much attention. However, the components related with advanced LED packages or modules have been issued on the heat from LED chip. And the LED chip is still being developed to the high power devices which are generating more heat. In this study, we investigated the variation of thermal resistance in LED modules embedded with thermal via. Through the analysis of thermal resistance with various test vehicles, we could obtain the concrete relationship between thermal resistance and structure of thermal via.

Performance evaluation and reliability of thermal vias

Abstract: Establish a high-yield design approach for surface mount power packages utilizing PWB thermal vias, elastomeric material and heatsinks. A feasibility study proved that the thermal via concept could be implemented to meet cooling and producibility requirements. Reliability testing demonstrated negligible thermal path degradation for a 15-year life equivalent in airborne environment.