The Effect of Contact Angle and Solder Bump Arrangement on Underfill Process

This study was devoted to investigate the effects of the contact angle and the bump arrangement on the underfill flow. The Hele-Shaw flow model, that considered the flow resistance in both the thickness direction between the chip and substrate and the plane direction between solder bumps, was assumed. A modified capillary force model including the effects of the contact angle and the bump arrangement was proposed. The capillary force was formulated based on either quadrilateral or hexagonal bump arrangements. A hexagonal arrangement of solder bumps was studied