SMPS transformer has square spool

[Flyback]

Hi,
The below E25 bobbin is square, ...surely that has more chance of stressing the enamel insulation at the corner bits?

E25 bobbin

CPH-E20/10/6-1S-8P | DigiKey Electronics

Order today, ships today. CPH-E20/10/6-1S-8P – Supplier Device Package E 20 x 10 x 6 from Ferroxcube. Pricing and Availability on millions of electronic components from Digi-Key Electronics.

www.digikey.co.uk

 

[ZipZapOuch]

Hi,
The below E25 bobbin is square, ...surely that has more chance of stressing the enamel insulation at the corner bits?

E25 bobbin

CPH-E20/10/6-1S-8P | DigiKey Electronics

Order today, ships today. CPH-E20/10/6-1S-8P – Supplier Device Package E 20 x 10 x 6 from Ferroxcube. Pricing and Availability on millions of electronic components from Digi-Key Electronics.

www.digikey.co.uk

Surely? Please explain. But as you explain, consider that the cross section of every E- core is square and every toroid's cross-section is square or rectangular.