Problems of noncontact thermography measurements of HICs

The temperature is an important physical parameter influencing hybrid integrated circuit (HIC) performance and reliability. Different interesting techniques using infrared thermography have been proposed. However, they do not give an absolute temperature, require an electronic system to synchronize the camera and the electronic device or have difficulties to obtain relevant thermograms because of the problem of low emissivity on the one hand and the poor spatial resolution on the other hand. In the paper are analyzed the specialties of HICs under thermography inspection. A HIC consists components with different geometry that are made of materials with strongly varying radiation properties. Therefore almost each of the point in the thermal image has to be considered with individual emissivity value. In most cases the general knowledge concerning emissivity coefficient e in function of angle of view, temperature and surface property is unknown. The lack of knowledge on the mentioned parameters values can results in a measurement error in tens or even hundreds percent of the true temperature. One approach for quantitative temperature measurements of HICs using infrared thermography with experimental set up is presented.