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DFM Practical Topic 11: Process Challenges with Castellated Holes: How to Prevent Copper Peeling and Burrs?

Poorly manufactured edge semi-plated holes are not merely an aesthetic issue—they are a nightmare of skyrocketing rework rates and batch short circuits. Many R&D teams only realize the problem when their boards are rejected by the assembly factory. They then discover that the cutting stress generated by clockwise rotating CNC milling cutters directly causes copper skin delamination at the “B point” of the semi-plated hole. In today's pursuit of modularity and extreme space utilization, edge castellated holes have become the core technology for board-to-board connections. But if you don't understand forming stress management, this board will be a shredder for your wallet.