A rigid wave pattern formed on a first side of a substrate in a semiconductor die package. The rigid wave pattern aligns with and overlies the contact fingers formed on the second side of the substrate. The rigid wave pattern includes a first pattern with an etched portion and an unetched portion around the etched portion. When the substrate and dice are encased during the molding process, the rigid wave pattern effectively reduces deformation of and stresses on the dice, therefore substantially alleviating die cracking.