Plate fin heat exchanger PFHE are usually composed of baffles, fins, seals, and guide fins. Fins, deflectors and seals are placed between two adjacent partitions to form an interlayer. PFHE such interlayers are stacked according to the different ways of the fluid, and welded into a whole by special vacuum diffusion welding to form a plate bundle, that is, plate fins in the core of the heat exchanger.