Abstract: A dam or barrier around the periphery of a die in a flip-chip package changes the shape of the underfill to reduce stress resulting from edge effects. The dam can include a treated region of a substrate having an affinity to an underfill material. The treated region causes liquid underfill material to bead, thereby controlling the wetting angle of the underfill material and shaping the underfill to eliminate sources of stress such as underfill fillet regions that are subject to significant shrinkage. The dammed underfill additionally avoids or reduces the extent of areas having thermal coefficients of expansion that differ from the optimal level because of low filler particle concentration.

Abstract: A dam or barrier around the periphery of a die in a flip-chip package changes the shape of the underfill to reduce stress resulting from edge effects. The dam can include a treated region of a substrate having an affinity to an underfill material. The treated region causes liquid underfill material to bead, thereby controlling the wetting angle of the underfill material and shaping the underfill to eliminate sources of stress such as underfill fillet regions that are subject to significant shrinkage. The dammed underfill additionally avoids or reduces the extent of areas having thermal coefficients of expansion that differ from the optimal level because of low filler particle concentration.

Abstract: A flip-chip packaging method for a semiconductor device treats a portion of an interconnect substrate so that a fill material when liquid beads on the treated portion of the interconnect substrate. When the fill material is dispensed on the interconnect substrate to fill a gap under the semiconductor device, the beading of the fill material prevents formation of fillets that might otherwise create a variation in the thermal coefficient of expansion of fill material and/or warp the interconnect substrate. The treated portion of the interconnect substrate can be roughened or coated with a material that differs from other portions of the interconnect substrate and thereby causes beading.

Abstract: A dam or barrier around the periphery of a die in a flip-chip package changes the shape of the underfill to reduce stress resulting from edge effects. The dam controls the wetting angle of the underfill material to provide a much smaller stress component perpendicular to the surface of the underlying substrate and shapes the underfill to eliminate sources of stress such as underfill fillet regions that are subject to significant shrinkage. The dammed underfill additionally avoids or reduces the extent of areas having thermal coefficients of expansion that differ from the optimal level because of low filler particle concentration.

Abstract: A process for fabricating a BGA flip chip package containing a stiffener or heat spreader monitors edges of the adhesive that attaches the stiffener or heat spreader. The monitoring ensures that the adhesive extends beyond the centers of the outermost solder balls in the BGA. Stress at the edge of the adhesive thus does not cause warping or variations within the BGA.