What is head in pillow defect?

Head-in-Pillow defect is a common manufacturing defect that can occur in electronic components such as integrated circuits and surface mount devices. It arises due to the improper bonding of the die and the substrate during the assembly process. It is called head-in-pillow defect because the die looks like a head resting on a pillow, with a gap between the two.

This defect can cause intermittent or permanent electrical failures leading to product malfunction, and it is often difficult to detect or debug. It can also affect product reliability and quality. The defect usually occurs due to insufficient solder wetting caused by temperature and humidity changes during the assembly process.

Prevention of head-in-pillow can be achieved by optimizing the bonding process, using proper thermal and humidity control, and ensuring that the components used are of high quality. Inspection techniques such as x-ray and visual inspection can be used to detect the defect. If detected, the component must be replaced or reworked to avoid failure and ensure high product quality.