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Thermal emission is already considered to be one of the basic analytical tools of today’s fault location and analysis. It provides an indispensible method for locating defects in all kinds of packaging, PCB, wafers, and more. |
Based on its principles, along with a few additional accessories, it is also possible to conduct thermal mapping of components and packages in order to understand the actual temperature values of component surfaces during operation. This information is crucial for improving the design of a chip or package.
To put it simply, when you provide a packaged component with a voltage, you will get a current. That, in turn, will generate “heat”. That “heat” will have different thermal radiation rates depending on the materials (metals, oxides, etc.). Begin by placing the heating stage under the sample. Once thermal equilibrium is reached, a thermal emissivity map of the object being tested is made by using the two-point temperature correction method. The temperature distribution in the sample area can be determined via the machine’s precise calculations, and the tangent approach can be used to draw the temperature curve between two points. This method has definite advantages when it comes to judging the heat and temperature distribution of a material.
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Something You Should Know: What is Emissivity? |
Emissivity is the ability of a material to emit infrared radiation under various temperatures. It is also equivalent to the material’s infrared light absorption capacity under thermal equilibrium, so an object that absorbs almost no light will emit almost no light. For example, metals are less likely to emit infrared light than semiconductors because their emissivity value is very low. Since metals are less prone to heat radiation, you need to take emissivity into consideration and perform the necessary compensation calculations when conducting temperature measurements. This is particularly important when using hot spot detection to find defects because it is possible for the emissivity of the surface material to influence the hot spot, causing it to shift. This can lead to the misjudgment of defect locations.
Figure 1. Emissivity of Various Materials |
Figure 2. The color bar tells us the actual temperature of each hot zone |
Figure 3. 3D temperature distribution |
Figure 4. Before measuring the thermal distribution, it is necessary to set the thermal chuck for temperature calibration |
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Analytical Applications |
- Analytical Application: Observe the surface temperature distribution then determine the influence of the materials used on the component’s heat distribution
- Use the heating stage to measure component temperatures after thermal equilibrium and calculate various temperature statistics, such as the temperature/time curve, linear temperature variations and average temperature in an area
- Blackbody radiation lenses detect longer wavelengths, which have a higher penetration rate, meaning a more accurate calculation of thermal emissivity
Figure 5. The temperature distribution on the component can be presented in a linear, 2D manner. In addition, this temperature data can be expressed through a histogram, coordinates or some other forms of statistical expression |
Figure 6. Record temperature changes over time and use the data to analyze temperature trends under specific power-supply conditions |
