You're looking for a 3M Bumpon part.  The main directory for such things:

http://products3.3m.com/catalog/us/en001/manufacturing_industry/specialty_tapes/node_GSH0V016W0be/root_GST1T4S9TCgv/vroot_GSNYTMLW46ge/gvel_GSSLRYMDZXgl/theme_us_specialtytapes_3_0/command_AbcPageHandler/output_html

Probably something like this one:

http://products3.3m.com/catalog/us/en001/manufacturing_industry/specialty_tapes/node_GSJH2J3QL7be/root_GST1T4S9TCgv/vroot_GSNYTMLW46ge/gvel_GSSLRYMDZXgl/theme_us_specialtytapes_3_0/command_AbcPageHandler/output_html

Once you figure out the 3M part number, google on that and find a supplier.  Digikey and Mouser typically carry them in sane quantities.