LED chip detection problem

科努德

LED chip detection problem [Copy link]

LED chips are the core components of the LED industry, and excessive chip temperature will seriously affect the quality of LED products. However, the temperature distribution of the chip and the inside of the chip is always difficult to detect. The main problem is that the internal components are too small, especially the micron-level gold wire (about 10 microns), which cannot be detected by traditional thermocouples/thermal resistors. Infrared thermal imagers and special accessories can be used to detect the inside of LED chips. The temperature distribution of the positive and negative poles of the gold wire and the chip can provide R&D personnel with a basis for wiring design. In addition, it is necessary to confirm the heating conditions of each part of the chip to improve the quality of the LED chip.

However, it is difficult to detect micron-level LED gold wires and positive and negative electrodes with a thermal imager. Ordinary infrared thermal imagers can only detect targets of at least 0.2 mm, so special accessories are required for detection. If you need an infrared thermal imager, please send me a private message.

It should be noted that: 1. Minimum focusing distance: The minimum focusing distance is an important parameter of the infrared lens. Generally speaking, the closer the distance, the better the shooting resolution under the same conditions. However, most lenses cannot be detected close, and how close they are to the target is the minimum focusing distance.

Most thermal imagers currently have dual shooting modes for infrared and visible light. However, due to the small size of LED chips, thermal imagers need to shoot at the closest extreme distance, which is much lower than the minimum focusing distance of visible light. Therefore, visible light generally cannot be displayed in the thermal image, or the position of visible light and infrared thermal images is very different.

We can install a macro lens to check the LED chip. It should be noted that:

1. Macro lenses are difficult to focus, especially for small targets. If the rotation force of the lens is too large, the clear target will flash, so the correct focusing method is:

①Rotate the macro lens to the maximum, that is, rotate the lens to the longest position, and then the smallest target can be detected.

② Steady the camera, estimate that the lens is about 20mm away from the chip, the target is at the center of the lens, and the camera moves back and forth slowly;

③If the chip is too small, it is recommended to place a larger hot object on the same plane as the chip, focus the object accurately, and then move the lens toward the chip;

④ The thermal imager can also be fixed, select the longest macro lens, and slowly move the chip until the focus is accurate. In this method, pay attention to the looseness of the electrical channel on the chip when moving, and the chip must move slowly.

2. During the on-site inspection, it is recommended to use the following equipment to assist focusing:

A guide rail with position fine-tuning function can make the thermal imager move accurately and stably.

Adjustable pan/tilt mounted on rails (with standard camera fixing bolts). Camera mounted on a pan/tilt for stable movement and fixed angles.

3. Replacing the macro lens will cause temperature detection errors. After using a temperature-stable black body furnace or heat source to detect the temperature, the lens error can be corrected by comparing the corrected emissivity or transmittance with the temperature.

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It's temperature measurement

I have a question, how do you prove that your temperature measurement is accurate?