It is also critically important to analyse the device footprint when selecting a TIM. When working with a large device, a gap filler or putty is likely to provide better performance as it will conform easily to any surface irregularities and fill all voids and interstices of the product. This ensures a good thermal transfer will be achieved. A putty can be especially effective when working with a rough mating surface. This is due to the fact that it can be highly compressed without placing significant pressure on sensitive components. For low footprint devices however, a grease or a phase change material will often times be more effective.