Bobbinless Voice Coil Winding

Bobbinless voice coil winding is a sophisticated manufacturing process primarily used in high-end loudspeakers and micro-motors. The core challenge lies in maintaining geometric precision, mechanical strength, and electrical performance without the support of a traditional structural bobbin (former).

1. Material Selection

• Conductors: High-purity copper (OFC) or Copper-Clad Aluminum (CCAW) are preferred, selected based on conductivity, elongation, and tensile strength.

• Insulation Coatings: Polyurethane (UEW) or Polyesterimide (EIW) are used for their high-temperature resistance (180C and above) and strong adhesion.

• Adhesives: Epoxy resins or UV-curable glues provide rapid curing while remaining compatible with the wire's insulation.

  
  

2. Winding Equipment and Process Control

• Precision Winding Machines: Requirements include active tension control (typically 0.1 to 0.5N), high traversing accuracy (plus or minus 0.01mm), and adjustable speeds (1,000 to 3,000 RPM).

• Tension Management: Excessive tension causes wire stretching or breakage, while insufficient tension leads to loose coils. A closed-loop tension control system is utilized for stability.

• Layer Alignment: Servo motors control the winding density to eliminate overlapping or gaps, maximizing the copper fill factor.

  
  

3. Geometric Shape Control

• Internal Diameter (ID) Shaping: Removable mandrels (such as Teflon-coated metal rods) or low-melting-point alloy molds are used and removed via heating or dissolution after winding.

• End Securing: Lead ends are secured using precision dispensing or thermal compression welding to prevent unraveling.

• Interlayer Insulation: For multi-layer windings, thin layers of insulating adhesive (such as Polyimide) are applied to prevent inter-turn short circuits.

  
  

4. Curing and Post-Processing

• Curing Methods: UV curing (3 to 5 seconds) or thermal curing (80C to 120C for 10 to 30 minutes) is employed to ensure structural integrity without air bubbles or stress concentration.

• Demolding Technology: Coils are released through thermal expansion/contraction or solvent dissolution (for water-soluble mandrels) to ensure zero damage.

• Precision Calibration: Laser inspection paired with micro-adjustment fixtures is used to correct ovality, with tolerances typically held within plus or minus 0.05mm.

  
  

5. Quality Control and Testing

• Electrical Testing: Verification of DC Resistance (DCR) and inter-turn insulation using high-voltage pulse testing.

• Mechanical Testing: Vibration testing (20 to 2,000Hz) and lead-wire tensile strength tests (minimum 5N).

• Dimensional Inspection: Optical projectors or CCD vision systems measure the inner diameter, outer diameter, and total height.

  
  

6. Specialized Winding Processes

• Flat-Wire Application: Flat wire (Rectangular wire) increases space utilization but requires advanced techniques to prevent edge warping, such as pre-gluing or thermal-compression shaping.

• Segmented Winding: For multi-coil designs, the spacing between segments must be precisely controlled (plus or minus 0.1mm) to avoid magnetic interference.

  
  

About Guangdong Zongheng Technology Co., Ltd.

With 15 years of dedicated expertise, Guangdong Zongheng Technology focuses on the R&D and intelligent manufacturing of forming winding machines for Air-Core Coils, Alpha Coils, and Voice Coils. Our equipment is widely utilized in smartphones, 3C electronics, New Energy Vehicles (NEV), home appliances, aerospace, military, and nuclear power.

Contact Us:Phone: +86-139-2581-0131 (Mr. Feng)