Lead free solder columns and methods for making same

A solder column for mounting electronic components to a printed circuit board, comprising:

• an inner core comprising a first material having a first liquidus temperature;
• an outer sleeve surrounding at least a majority of an outer surface of the inner core, the outer sleeve comprising a second material having a second liquidus temperature;
• and
• a plurality of spaces along a length of at least one side of the inner core between segments of the outer sleeve;
• wherein:
• the solder column is configured such that the inner core will support the outer sleeve and prevent a collapse of the outer sleeve at temperatures above a liquidus temperature of the outer sleeve;
• and
• the spaces are configured to provide additional flexibility to the solder column to improve the ability of the solder column to absorb stresses caused by mismatches in a coefficient of thermal expansion between a first substrate coupled with a first end of the solder column and a second substrate coupled with a second end of the solder column.