When dealing with PCBs with heavy ground planes or where lead free solder is an issue, adding additional heaty from the bottom side of the PCB is often helpful to complete the task quickly, safely, and efficiently. Often lower top-side temperatures can be used (conductive or convective tools) with the addition of bottom-side heating.
PACE offers three different pre-heat options. The ST 400 uses IR based heating technology, the ST 450 uses convectove heating technology and nozzles to focus the heat where its needed, and the ST 1600 uses four individually controlled IR heating panels that can be used together or independently. The ST 1600 also featured the ability to attach a thermo-couple to the PCB and maintain a desired temperature.