A transformer bobbin (also known as coil former or plastic winding frame) is a critical component used in the construction of transformers, inductors, and coils. It is an insulating plastic structure designed to hold and organize the copper windings safely and efficiently.
The bobbin provides:
proper winding arrangement
electrical insulation between windings
mechanical stability and durability
easy PCB mounting and terminal connection
Materials
Transformer bobbins are manufactured using high-performance thermoplastics such as:
Nylon (PA66, PA6) – strong and heat-resistant
PBT (Polybutylene Terephthalate) – excellent electrical insulation
PET (Polyester) – good thermal and mechanical properties
LCP (Liquid Crystal Polymer) – for high-performance applications
UL94 V-0 flame retardant materials – enhanced fire safety
Features may include:
integrated metal terminals (pins)
high temperature resistance (Class B, F, H)
compliance with UL, RoHS, REACH standards
Applications
Transformer bobbins are widely used in:
