Patent ID: 8537301
Filing Date: 2013-09-17
Classification: B21K,H05K

Abstract:
1. A method, comprising: forming a chassis using a steel plate having a thickness in the range of about 0.5 mm to 0.9 mm, the steel plate having a stack structure comprising an inner layer, an electro-galvanized layer formed on the inner layer, and a polymer chromium (Cr)-free contamination resistant layer formed on the electro-galvanized layer, wherein the inner layer comprises approximately 0.001 to 0.1 weight percent (wt. %) carbon (C), approximately 0.002 to 0.05 wt. % silicon (Si), approximately 0.28 to 2.0 wt. % manganese (Mn), iron (Fe), and other impurities; and providing a burring part by performing a burring process and a tapping process on the chassis for inserting a bolt for an engagement.