A spb to vcf conversion typically represents export of contacts from Samsung Kies backup files (.spb) and saving them in a separate vCard file (.vcf, .vcard).
You can do this with Samsung Kies and its VCF/CSV export function, however, in some later version of the programs this function was removed. This leaves users that have old .spb backups in a tight spot with no direct way to simply export their contacts from .spb files without restoring whole backup.
If your version of Kies does not contain contact export function, you can always try some older version (Kies 2.x seems to work) that does not automatically update.
Unfortunately, Samsung does not offer previous versions of Kies, so you have to look on web for sites that cumulate older software. It is very likely that no spb to vcf converter utility exists, so using Kies is your only option as there does not appear to be other way to convert spb to vcf without Kies.
Updated: April 13, 2017