The electronegativity is 2.1 for h and 1.9 for pb. based on these electronegativities pbh4 would be expected to

PbH4 will be formed as a result of a polar covalent bond between the H and the Pb.

Since H is more electronegative than the Pb, it is, thus, expected that the H would be able to pull the electron charge towards itself. This will result in the H being negative.

Based on this:
PbH4 would be expected to have polar covalent bonds with a partial negative charges on the H atoms.