1. What is a self-welding connecting wire

Self-welding wire (often referred to as self-melting wire, self-adhesive enameled wire, or self-welding enameled wire) is a special type of enameled wire that is coated with a self-melting/self-welding insulating layer on the copper/aluminum conductor. The core idea is that after heating, the insulating layer can be melted and directly welded, without the need for scraping or removing the paint.
The industry is often divided into two major categories:

Self-solderable: The insulating layer (polyurethane PU / polyetherimide PEI) automatically decomposes and detaches at soldering temperature, allowing direct immersion tin soldering without scratching the paint.

Self-bonding (Self-melt type): The outer layer is coated with a layer of self-adhesive paint, which melts after heating and bonds the coil turns together after cooling, eliminating the need for a frame and varnish immersion for fixation.

II. Core Structure and Principle

1. Self-welding type (straight welding)

Conductor: Pure copper / tinned copper (high conductivity)

Insulation layer: Polyurethane (PU)/Polyesterimide (PEI) direct solderable varnish

Principle: At a soldering temperature of 250–350℃, the insulating layer undergoes thermal decomposition and volatilization, allowing the conductor to be directly coated with tin without the need for paint removal.

2. Self-adhesive / self-melting type (coil fixation)

Conductor: Copper

Inner layer: Conventional insulating varnish (polyester / polyesterimide)

Outer layer: self-adhesive paint (thermoplastic / thermosetting)

Principle: Heating (hot air / oven / high frequency) → self-adhesive layer melting → coil turn-to-turn bonding → cooling and solidifying into a whole, capable of being shaped even without a skeleton.

III. Key Features (Advantages)

Self-welding type (straight welding)

No need to scrape paint, high efficiency: eliminating the paint stripping process, suitable for automated batch welding

Clean solder joints with high reliability: no residual paint residue, low contact resistance

Heat resistance grade: 130℃ (UEW), 155℃ (PEW), 180℃ (PEIW)

Applicable standards: IEC 60317, NEMA MW series

Self-adhesive / Self-fusing type

No need for a skeleton, material-saving: The coil can be self-supporting, suitable for hollow coils

Varnish-free / Tape fixation: Simplifying the process and shortening the cycle

The coil exhibits good rigidity and vibration resistance, making it suitable for high-speed motors, loudspeakers, and high-frequency inductors

Remediable: The thermoplastic self-adhesive layer can be reheated and reshaped

IV. Typical application scenarios

Self-welding type (straight welding)

Micro motor, relay, solenoid valve coil

Home appliance control board, PCB coil, sensor

Automotive electronics, instruments, and small transformers

Consumer electronics: headphone coil, vibration motor

Self-adhesive / Self-fusing type

Skeletonless air-core coil (RF, antenna, inductance)

Loudspeaker voice coil, micro motor stator

High-frequency transformer, choke coil, solenoid valve

Aviation / Automotive Electronics: Vibration-resistant, High-reliability Coils