Let $f: L_1 \cup L_2  \subset R^3 $ be a two-component link.
The link $f$ is called a semi-boundary link if 
$lk( f(L_1);f(L_2))=0$. For an arbitrary semi-boundary link
$f$ the integer Sato-Levine invariant $\beta$ of the
isotopy class of $f$ is defined.
We generalize the invariant $\beta$
and define this invariant for an arbitrary link $f$.
We use an approach due to G.T.Jin (1987) and
consider the invariant $\beta$ as a Vassiliev invariant of order 3.