Patent ID: 6283359
Filing Date: 2001-09-04
Classification: B23K,H01L,H05K,Y02P,Y10T

Abstract:
A method for making solder electrical interconnections in an electronic component assembly comprising the steps of:applying a first solder having a first melting point to first pads on the surface of a first substrate of an electronic component assembly;forming a solder structure comprising:an inner core of a second solder having a second melting point which is higher than the melting point of the first solder to which the structure is to be bonded;a layer of a metal wettable by the first solder and having a melting point higher than the second melting point of the second solder of the inner core;an outer layer of a third solder having a third melting point which provides a wettable surface for attachment of the solder structure and passivates the layer of metal from oxidation and corrosion, the third melting point being lower than the second melting point;bonding the solder structure to the first pad by reflowing the first and third solders;applying a fourth solder to second pads on the surface of a second substrate of the electronic component assembly;positioning the second pads on the surface of the second substrate electronic component assembly to be joined proximate to the corresponding solder structure containing pads on the first substrate;heating the substrates to a temperature sufficient to form a bond between the solder structure and the pads of the second substrate; andcooling the bonded interconnected assembly.