PDF《Application Note》

Discrete Semiconductor DevicesHints and Tips for Thermal Design ? Part

2 Application Note 2018-07-26

1 ?

2018 Toshiba Electronic Devices &

Storage Corporation Description This document provides hints and tips based on simulation results to help you reduce the chip temperature of discrete semiconductor devices.

Discrete Semiconductor Devices Hints and Tips for Thermal Design ? Part

2 Discrete Semiconductor DevicesHints and Tips for Thermal Design ? Part

2 Application Note 2018-07-26

2 ?

2018 Toshiba Electronic Devices &

Storage Corporation Table of Contents Description.1 Table of Contents

2 1. Introduction

3 2. Summary of simulation results

3 3. Simulation accuracy.4 4. About simulation models.5 5. Thermal interference model

7 6. Simulation results and tendencies for chip temperature

8 6.1. Effects of multi-layer PCBs

8 6.2. Effect of the PCB trace thickness.9 6.3. Effect of vias just below E-pad

10 6.4. Effect of peripheral vias

11 6.5. Effect of the heatsink size.13 6.6. Effect of heatsink emissivity.13 6.7. Effect of thermal interference

15 6.8. Effect of a TIM.17 RESTRICTIONS ON PRODUCT USE.19 Discrete Semiconductor DevicesHints and Tips for Thermal Design ? Part

2 Application Note 2018-07-26

3 ?

2018 Toshiba Electronic Devices &

Storage Corporation 1. Introduction Hints and Tips for Thermal Design for Discrete Semiconductor Devices uses actual measurement data as a basis to provide thermal design tips for reducing chip temperature. As a sequel, Part

2 describes thermal design tips based on simulation data. Simulation allows great flexibility in analysis once analysis models are created. It is beneficial in that analysis data can be obtained under various test conditions and environments. Unlike real-world devices, devices under simulation do not fail even under extreme conditions. Simulation can therefore replicate conditions that are nearly impossible with actual devices. We exploited this advantage of simulation to obtain data using models and conditions that are impossible with actual measurement. This application note provides a summary of simulation results. Simulation allows conditions that cannot be replicated physically, making it easy to predict results in extreme device conditions. Therefore, Hints and Tips for Thermal Design for Discrete Semiconductor Devices ? Part

2 provides data that are unavailable in the previous application note based on actual measurement. 2. Summary of simulation results Simulations are performed under certain fixed conditions. An actual decrease in chip temperature depends on conditions. You can expect, however, that the tendencies in chip temperature that were revealed by simulation also apply to real-world devices. The following table summarizes the simulation results. Use these data as a reference for thermal design. Detailed conditions and data are provided in subsequent sections. Countermeasure Reduction in Chip Temperature Comment Multi-layer PCB Dropped by 7% when the number of PCB layers was increased from

4 to

8 Consideration is required for a PCB because increasing the number of PCB layers, albeit effective, incurs extra cost. PCB trace thickness Dropped by 6% when the trace thickness was increased from

70 μm to

105 μm Increasing the thickness of PCB traces increases their cross section and therefore causes heat to disperse across the PCB more quickly. Vias just below a drain frame Compared to a PCB with no via: Dropped by 9% when three vias were added and by 12% when five vias were added Considerably effective Peripheral vias Compared to a PCB with no via: Dropped by 7% when six vias were added and by 10% when ten vias were added Not as effective as vias placed just below the drain frame However, peripheral vias may prevent heat from conducting to surrounding areas. Heatsink size Compared to no heatsink: Dropped by 12% with a heatsink with a height of