Microelectronic device with pillars having flared ends

A microelectronic device has a die with a die conductor at a connection surface. The microelectronic device includes a pillar electrically coupled to the die conductor, and a head electrically coupled to the pillar. The pillar has a die-side flared end at a die end of the pillar; the pillar widens progressively along the die-side flared end, and extends outward by more than a lesser of half a thickness of the die conductor and half a lateral width of the pillar midway between a die end and a head end. The pillar has a head-side flared end at a head end of the pillar; the pillar widens progressively along the die-side flared end, and extends outward by a distance that is greater than a lesser of half a thickness of the head and half the lateral width of the pillar. Methods of forming the microelectronic device are disclosed.