SBOA600 July   2024 ISOTMP35

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
    1. 1.1 Calculating Thermal Response Time
    2. 1.2 Current Design with Non-Isolated Temperature Sensors
    3. 1.3 Proposed Design Using the ISOTMP35 Isolated Temperature Sensor
  5. 2Experiment Setup
    1. 2.1 Step 1: Prepare the Oil Bath
    2. 2.2 Step 2: Prepare the Liquid Gallium
    3. 2.3 Step 3: Submerge the Copper Pad
    4. 2.4 Step 4: Prepare Each PCB Configuration
    5. 2.5 Step 5: Testing Each PCB Configuration
    6. 2.6 Test Results
  6. 3Summary
  7. 4References

2.4 Step 4: Prepare Each PCB Configuration

For the experiment, three options were tested: the ISOTMP35, an NTC soldered just across the clearance boundary, and an NTC thermally coupled to the copper pad with thermal epoxy, 2 boards each.

The thermal epoxy chosen was Dycotec Materials Ltd DM-TIM-15340-SYP, which is a thermal epoxy with a thermal conductivity of 3.7W/mK. While this is less than the 400W/mK conductivity of a direct copper connection, it is still a significant improvement over the 0.2W/mK conductivity of FR4 alone.

NTC Soldered onto Test PCB, Across Minimum ClearanceFigure 2-7 NTC Soldered onto Test PCB, Across Minimum Clearance
NTC with Cured Thermal EpoxyFigure 2-8 NTC with Cured Thermal Epoxy