Device identity and key specs
The 1.5SMC15A-M3/57T: It clamps at 21.2 V maximum with a peak pulse current of 70.8 A, making it a solid choice for protecting 12 V rails against transients like load dump or inductive kickback. The reverse standoff voltage is 12.8 V typical, and breakdown occurs at a minimum of 14.3 V, so it sits just above a nominal 12 V supply without leaking during normal operation.
Package and rework reality
The body is large enough that orientation is obvious: the cathode band is clearly marked, so you won't struggle to find pin 1 under a hot-air station. With a -65°C to 150°C junction temperature range, it survives the reflow cycle without moisture sensitivity issues if stored per the standard floor-life rules for MSL 1.