SLYT793A may   2020  – may 2020 LM61460-Q1

 

  1.   1
  2. 1 Introduction
  3. 2 Managing Thermals with Flip-chip Packages
  4. 3 Board Construction Influence
  5. 4 Copper Area and Thermals
  6. 5 Estimating a Converter’s Junction Temperature
  7. 6 Challenges with Measuring Converter Junction Temperature
  8. 7 Further Thermal Optimization at the IC Level
  9. 8 Conclusion
  10. 9 References
  11. 10Related Web Sites
    1. 10.1 General Information:
    2. 10.2 Product Information:

4 Copper Area and Thermals

PCB layout is the biggest influencer on power-converter thermal performance, with package thermal metrics close behind. The RθJA metric describes a board’s thermal performance. It quantizes the thermal resistance between the ambient air and a semiconductor p-n junction on the converter’s die. A primary influencer on RθJA is the effective copper area available for heat sinking.

Figure 5 demonstrates the impact of available copper area on RθJA, with data collected by reducing the copper area of the two- and four-layer PCBs equally for each RθJA measurement. The data can determine the effect of having more copper area on thermal performance. The measured device RθJA can provide an estimate for the ambient temperature at which the device will be able to operate.