Low-leakage planar transformers for welding-type power supplies

A welding-type power supply, comprising:

• a main circuit board;
• power conversion circuitry coupled to the main circuit board and configured to convert input power to welding-type power, the power conversion circuitry comprising a switched mode power supply, the switched mode power supply comprising:
• a switching element coupled to the main circuit board;
• a planar transformer coupled to the main circuit board, the planar transformer comprising:
• a magnetic core;
• a first primary winding board secured to the magnetic core and coupled to the switching element;
• a first secondary winding board secured to the magnetic core, wherein each of the first primary winding board and the first secondary winding board comprise:
• a first printed winding on a first layer of a circuit board;
• first and second mounting tabs on the first layer of the circuit board or a third layer of the circuit board, and coupled to the first printed winding;
• a second printed winding on a second layer of the circuit board;
• and
• third and fourth mounting tabs on the second layer of the circuit board or a fourth layer of the circuit board, and coupled to the second printed winding;
• and
• a first spacer positioned between the first primary winding board and the first secondary winding board to position the first primary winding board a predetermined distance from the first secondary winding board;
• and
• an output stage circuit coupled to the main circuit board and coupled to the first secondary winding board.