Reel-to-reel manufacturable, leadless surface mountable, Z-folded planar power transformers

A reel-to-reel assembly process and winding layout techniques for leadless surface mounted Z-folded planar transformers are presented. Electrical performance of 2-pole transformer geometries without a need for internal connections are compared with 1-pole transformer where the need for soldered contacts makes the manufacturing more complicated. Design equations for candidate transformer geometries were developed and refined using Finite Element Method (FEM) analysis and prototype measurements. According to the results the 1-pole geometry shows better performance in terms of minimum power losses for a given transformer volume while the 2-pole transformers yield lower power losses with minimum FLEX area and may be preferred when cost - performance is considered. Life Cycle Cost (LCC) - analysis was utilized to study this issue in more detail. Material costs for transformers with width = 17mm, length = 24mm, height = 6mm and total losses = 1W (99.2% efficiency) were estimated to be 0.67$ for 1-pole transformer and 0.54$ for 2-pole transformer. Prototype transformers were manufactured and measured to demonstrate and validate the proposed component technology and analysis.