"The flexi-quota, as I envision it for executive boards, allows companies full decision-making and structuring power with the loosest possible legal obligation," Schröder told financial weekly Wirtschaftswoche this weekend.
Schröder is determined to initiate the law's progress through parliament this year, despite opposition from the government's coalition partner the Free Democratic Party (FDP).
"A legal gender quota is not our thing," FDP leader and Economics Minister Philipp Rösler told the magazine. "Every company can already say voluntarily what quota they want to reach, and how they want to be measured."
The government is holding a meeting with the chief personnel officers of the 30 DAX-listed companies on Monday to discuss how more women could be brought into leading positions.
In March, company managers promised to create individual targets to put more women into executive boards. Schröder said, "I expect there won't be a single single-figure quota on the list of individual self-made targets that the companies present to me."