Here is some useful information on this issue. Will add to it as more material comes in.
Jim Stanford has reviewed Private Member Bill C-525 it and finds that it does more than eliminate card check in the federal sector. It also changes how votes would occur. Jim notes that cards representing 45% of a bargaining unit will be required to trigger a vote; union would have to win a majority of all members in the bargaining unit (not ballots cast); and a decertification vote can be triggered by 45% signatures, the UNION must receive support from the majority of the bargaining unit.
Leftnews.org has more information on Bill C-525. It explains the impact the Bill will have on card-check certification and provides research on why card check has proven to be the preferred method of certifying and de-certifying.