E-cigarette Shell LSR Overmolding on PC

I. Product Overview

E-cigarettes are emerging electronic consumer products. LSR overmolding on PC (Polycarbonate) technology coats Liquid Silicone Rubber onto PC shells through precision injection molding, creating a dense, flexible, chemical-resistant silicone protective layer. The process combines PC's rigid support with LSR's elastic touch sensation, widely applied in high-end e-cigarette bodies, pod protective covers, mouthpiece seals, and other core components.

II. Core Advantages of LSR on PC

1. Superior Sealing Protection - LSR coating seals assembly gaps and screw holes, achieving IP67 dust/water resistance. Prevents e-liquid, tea, and sweat from penetrating internal circuits.

2. Excellent Grip & Anti-slip Design - LSR provides soft, delicate touch (Shore A 20-50 adjustable). Matte and anti-slip texture options available for secure grip even in humid conditions.

3. Drop Impact Protection - 0.5-1.5mm LSR layer absorbs approximately 60% of impact energy from 1.5m drops, reducing PC shell breakage risk by over 300%.

4. Chemical Resistance & Anti-yellowing - LSR resists PG, VG, and flavoring corrosion in e-liquid. UV-stable formulation ensures no significant yellowing after one year of outdoor use.

III. Molding Process Details

3.1 Two-shot / Secondary Injection Process

Step 1 - PC Base Injection: Precision injection molding of PC frame (wall thickness 0.8-1.2mm, mold temp 80-100°C, injection temp 280-310°C). Annealing at 120°C x 2h to release internal stress.

Step 2 - LSR Overmolding: PC frame placed into overmolding tool. Key parameters: mold temp 150-170°C, injection pressure 60-100MPa, curing time 30-60s, coating thickness 0.5-1.5mm.

3.2 PC-to-LSR Bonding Technology

PC surface energy is only 42-46 mN/m. Solutions include: (1) Oxygen plasma treatment (300W, 30s) raising surface energy to 65+ mN/m; (2) Specialized primer coating (Dow Corning 1205OS, 2-5μm); (3) Precise injection pressure control at 80-100MPa.

3.3 Mold Design Key Points

Submarine or tunnel gate to avoid visible gate marks. Proper venting (0.02-0.05mm depth). Mold cavity temperature uniformity within ±2°C. Draft angle 3°-5° for easy demolding.

IV. Quality Control Standards

Visual Inspection - AOI detection for voids, bubbles, flash, color variation.

Peel Test - 90° peel strength (ASTM D429) ≥5N/mm at LSR/PC interface.

Seal Test - Air leak test at 0.3MPa for 20s, leakage<3mL/min. IPX7 immersion test (1m, 30min).

Oil & Aging Test - E-liquid immersion at 50&deg;C x 72h. QUV accelerated aging 1000h, yellowing index &Delta;E<3.0. Thermal cycling -20&deg;C to 85&deg;C, 100 cycles.

V. Applications

Our LSR-on-PC e-cigarette shell products have been successfully applied in: high-end pod vape bodies with matte LSR finish and IP67 waterproof; disposable vape full-body LSR coating (12 Pantone colors); pod clear silicone covers; mouthpiece silicone seals (medical grade USP Class VI, food contact certified).