Molded Underfill (MUF) Inspection

Molded underfill (MUF) is increasingly being used to lower costs and increase throughput in flip chip assembly. Compared to older underfill processes, MUF decreases material costs, allows for batch processing of both underfill and overmolding in strip format, and enables smaller package size for today’s powerful mobile devices.
 
The main challenge when inspecting MUF flip chips is that the acoustic signal and its reflections need to penetrate the overmold layer, which is not as transparent to ultrasound as bare silicon. Also, the uneven particle size within the MUF epoxy base causes uneven scattering and absorption of the signal. Sonix MFCI™ software addresses these challenges to improve spatial resolution, edge resolution and contrast in advanced MUF flip chip applications.