An undermount sink with laminate countertop would be acceptable but you may have some problems with the edges of the laminate near the sink chipping. An undermount sink would probably work better with a granite or other hard surface, or perhaps a sink which is one piece with the countertop.
You can have an under-mount sink with any type of material. The sink mounts to the underside of the counter top which usually has a particle board surface.
These are typically insalled in a hard surface, such as grantie/marble etc. The laminate countetop is much more porous, allowing water and moisture to collect around the sink edge. Eventually the counter top will begin to swell, then separate from the particle board, which will result in the destruction of your countertop.