Patent ID: 8833636
Filing Date: 2014-09-16
Classification: B23K,H01L

Abstract:
1. A method for transferring an array of metal balls on a polymer layer to an array of metal contacts on a substrate comprising: selecting an array of contacts on a substrate; forming a flux over respective contacts of said array of contacts on said substrate; forming on said substrate a first mask having through-hole openings corresponding to respective contacts of said array of contacts; said through-hole openings having a depth and a width for receiving metal balls of said array of metal balls on said polymer layer; said first mask having mechanical strength to maintain a shape of said through-hole openings under shear forces to permit shearing said metal balls of said array of metal balls; positioning respective metal balls of said array of metal balls on said polymer layer into said through-hole openings of said first mask; moving said first mask sideways with respect to said polymer layer and said array of metal balls at least the width of a metal ball to shear said array of metal balls and stopping said moving said first mask sideways whereby said metal balls of said array of metal balls are sheared free from said polymer layer in said through-hole openings over said flux and respective contacts; heating said metal balls to reflow said metal to bond to or wet said respective contacts in a presence of said flux; and solidifying said metal over said contacts.