Design a PCB Planar Transformer in DipTrace

Important
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Uses Fractional Turns – See the paper “How to Design a Transformer with Fractional Turns” by Lloyd H. Dixon, Jr.
https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.187.2764&rep=rep1&type=pdf
Page R6-4 has the winding layout for obtaining the 1/2 turn while minimizing leakage inductance.

Work
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1. Design the PCB for a PCB flyback transformer for SMPS use. The transformer “windings” are to be compromised of a double-sided (2-layer) Aluminum core PCB with up to three additional 6-layer Polyimide Flex PCBs stacked on top. See below for the PCB Stack-Ups.
The PCBs must allow for reflow soldering the stacked PCBs together.

2. Determine the E-core magnetics for the PCB flyback transformer.

3. Create a component footprint for the E-core magnetics.

4. Create a scale 3D component model of the E-core magnetics.

5. Ensure the PCB preview is correct with the 3D E-core model.

PCB Transformer Requirements

Power rating: 2.05W Continuous at 60DegC, 1.1W Continuous at 115DegC
Switching Frequency: Preferred 400KHz Maximum 1 MHz The switching frequency can be reduced to whatever your design requires.
Switching Duty Cycle: Preferred maximum is 45% on-time The duty cycle can be adjusted to whatever your design requires.

Winding Layout:
Pri – Common to A: 1 TS 0.855 Amp Max @ 115 Deg C
Pri – A to B: 1 TS 0.428 Amp Max @ 115 Deg C
Pri – B to C: 4 TS 0.143 Amp Max @ 115 Deg C

Sec – Gnd to 1.1V: 4 TS 0.660 Amp Max @ 115 Deg C
Sec – 1.1V to 1.2V: 1/2 TS 0.332 Amp Max @ 115 Deg C
Sec – 1.2V to 1.8V: 2 TS 0.133 Amp Max @ 115 Deg C
Sec – 1.1V to 3.0V: 7 TS 0.443 Amp Max @ 115 Deg C
Sec – 3.0V to 3.3V: 1 TS 0.323 Amp Max @ 115 Deg C

Total Pri turns: 4
Total Sec turns: 14 and a single 1/2
Total turns: 18 and a single 1/2

Largest Circuit Board Stack
6-layer Polyimide Flex 5-layers usable
6-layer Polyimide Flex 5-layers usable
6-layer Polyimide Flex 5-layers usable
2-layer Aluminum (Core in Middle 2.0W) 2-layers usable

Fewer Polyimide Flex PCBs are preferred.

PCB Stack-Up for Aluminum Core
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Aluminum (Core) Board (Conductivity: 2.0W)
Metal core in the middle
2-Layer
3.2 mm thick
5/5 mil
ENIG
2 oz Cu

PCB Stack-Up for Polyimide Flex
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Flexible PCB
6-layer Polyimide Flex
FPC Thickness: >= 0.35 mm
2/2 mil
Min Hole: 0.15mm
Stiffener: Without
ENIG 0.0254um
2 oz Cu
3M Tape: 3M467 Both Sides 2×0.158mm = 0.316mm
EMI Shielding Film: Without

Deliverables
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* DipTrace 4.x .dch schematic file
Wire classes must be assigned and set to the correct current ratings.
ERC must run without errors.

* DipTrace 4.x .dip PCB file containing all PCBs in the stack-up
DRC parameters must be set. The DRC must run without errors.
Traces must have the correct classes assigned for the current ratings.
Automatic comparison with the schematic (.dch) file must run without error.

* PCB stacking directions

* Manufacturer and part # for the E-core magnetics
The part must be currently order-able from either the manufacturer or a major electronics component distributor.