THERMISTOR SENSOR
Solution
Achieves long lifespan of
LED headlights
Challenge
Hope to suppress deterioration due to LED heat
- The heat generated by the LED causes the increase in thermistor resistance value and the decrease in temperature accuracy, which in turn causes the LED to overheat and shorten its life.
- Sulfurization migration can cause the thermistor to short-circuit, which then leads to the LED stopping working.
Solution Overview
LED headlights have a reduced life when the LEDs are operated in a high temperature environment. Therefore, the temperature of the LED is monitored using a thermistor, where the LED current is derated, and the overheating of the LED is suppressed.
■ Features of our chip thermistors
- High resistance accuracy and temperature accuracy
- 4-sided glass coating makes high reliability (mechanical strength, environmental resistance, and migration resistance is improved)
- Large electrostatic breakdown resistance
- Excellent high frequency characteristics
Others, (Multilayer →non glass coating)
Since the thermistor element and the electrode have weak adhesion, the element is eroded during plating and the electrode is peeled off.
Our TD series
Since the glass and electrodes have strong adhesion, the element does not erode during plating.
Effect
-
Before
■ Heat Resistance
The resistance value of the thermistor rises due to deterioration over time, which causes the temperature to be detected as lower than the actual one. If this happens, the current will be controlled incorrectly, and the LED will be exposed to a high temperature environment. Furthermore, even if the LED junction temperature is exceeded, it is not detected as an abnormality and may cause a decrease in the LED lifespan.
-
After
■ Heat Resistance
Our TD series chip thermistor has excellent heat resistance, very small change in resistance value at high temperature, and outstanding temperature accuracy. It monitors the LED temperature accurately, thus contributes to a longer lifespan of the LED.
-
Before
■ Migration
Without the glass protective film, sulfurization migration may occur and the LED may not light up. A sulfide migration test was conducted in which another company's product without a protective film and our product were put into cutting oil at 80oC and DC 5V was continuously applied between the thermistor terminal electrodes with a constant current power supply. The photo on the left shows the appearance of another company's product after testing, and migration was confirmed after 5 hours of energization.
-
After
■ Migration
Our thermistor is glass-coated and the Ag base electrode is not exposed, so the occurrence of sulfurization migration is suppressed. (The picture on the right)
ADVANTAGE
-
ADVANTAGE01
Our chip thermistors (TD series) have excellent long-term reliability and are ideal for LED headlights.
-
ADVANTAGE02
Our chip thermistor has a unique four-sided glass coating structure that suppresses the occurrence of sulfurization migration. No sulfurization migration issues occurred to our thermistors in the past.
OTHER SOLUTIONS
Other solutions for thermistor sensor
-
THERMISTOR SENSOR
Want a heat-resistant product compatible with SiC power semiconductors
-
THERMISTOR SENSOR
Hope to measure sudden temperature changes with good response
-
THERMISTOR SENSOR
Hope to discuss the structure and shape of the sensor
Other related solutions
This solution utilizes
Mitsubishi Materials' thermistor sensor.
