| 摘要 |
A method and preform for forming and attaching an array of conductive balls, preferably solder balls, to ball receiving areas on a substrate is disclosed. The preform is a connected array of sub-preforms comprised of the conductive material from which the balls will be formed. The connections between adjacent sub-preforms are designed to assure division of the preform into individual masses, each sufficient to form one conductive ball. Each sub-preform is provided with a bottom protrusion which assures physical and thermal contact between preform and substrate. The method involves placing the preform on the substrate such that each sub-preform is positioned above the conductive ball receiving areas. The preform and substrate are than heated to above the melting point of the conductive material to melt the conductive material and form metallurgical bonds between the conductive material and the receiving areas. Surface tension causes the sub-preforms to separate from one another along discrete fuse zones and form into individual conductive balls. Cooling the assembly to below the melting temperature of the conductive material fixes the configuration and positions of the array of conductive balls on the ball receiving areas of the substrate.
|
