What the 7403DC is and where it fits
The 7403DC is a TTL NAND gate with open-collector outputs.
Lifecycle and compliance — what it means for your BOM
The RoHS non-compliant marking is the key constraint: this part contains lead (Pb) in the solder finish or die attach, which means it cannot be used in new EU RoHS-exempted designs without a specific exemption (e.g., for high-reliability or aerospace applications that still permit leaded solder). For BOM planning, factor in the need for a RoHS compliance statement or an explicit exemption waiver if your end-market requires it.