It comes in a through-hole DO-15 axial package. This class of ultrafast diode is typically used in high-frequency rectification, freewheeling, and snubber circuits in switch-mode power supplies, lighting ballasts, and motor drives where low switching losses matter. The 30 ns trr keeps reverse-recovery losses down in the 50–100 kHz range, which is where this part earns its keep.
ST lists the STTH2R02QRL as Obsolete. If you are qualifying a replacement, the closest functional match will need the same 200 V / 2 A rating, 30 ns or faster trr, and a through-hole DO-15 footprint.
30 ns trr — the switching-speed spec that matters
The 30 ns reverse recovery time is the key parametric that separates this diode from a standard recovery part. In a 100 kHz PFC boost stage, that 30 ns means the diode turns off fast enough to avoid excessive ringing and dissipation. If you are swapping in a replacement, the trr needs to be equal or faster — a 50 ns part will run hotter in the same spot. The forward voltage drop is 1 V at 2 A, which is typical for a 200 V ultrafast in this current class.
DO-15 axial — the footprint constraint
The DO-15 (DO-204AC) axial package is a through-hole leaded form factor. If your board has a hole pattern for a DO-15, any replacement must also be a DO-15 axial — a surface-mount equivalent would require a different PCB layout. There is no SMD version of this exact part; if you need a surface-mount diode with similar ratings, you would be looking at a different package family (e.g., SMB or SMC) and a different order code entirely.