Client: A Leading Metro System Operator (Asia)
Application: Underground Tunnel Communication Systems

1. Operational Challenges

Environmental Conditions:

• 24/7 high humidity: 95% RH (Relative Humidity)
• Condensation cycles with temperature fluctuations (15°C–45°C)
• Continuous vibration from passing trains

Critical Failures Observed:
▶ Insulation resistance (IR) dropped to <1GΩ within 6 months
▶ Bit Error Rate (BER) surged to 10⁻⁴ (vs. required 10⁻⁸)
▶ Frequent corrosion-induced signal loss (3+ annual maintenance interventions)

2. KKPCB’s Robust Manufacturing Solution

Core Technical Innovations

Technology	Implementation	Performance
Nano-Ceramic Coating	KKPCB Patent #201910XXXXXX	5μm protective layer on glass fiber surface
Reverse Pulse Plating	25μm+ hole wall copper thickness	Ion migration resistance >200h @85°C/85%RH
Modified Epoxy Laminate	Halogen-free high-CTI material	CTI ≥600V, IR >10¹²Ω after moisture exposure

Key Process Controls

• Humidity-proof lamination:
  • Pre-baking at 125°C for 4hrs to eliminate moisture
  • Vacuum pressure: <10Pa during pressing
• Anti-corrosion treatment:
  • Immersion silver + organic coating dual surface finish
  • Salt spray resistance: 96hrs @35°C (5% NaCl)

3. Verified Performance Data

Reliability Testing (IPC-6012DA Class 3)

Parameter	Pre-Improvement	KKPCB Solution
Insulation Resistance (IR)	0.8GΩ	12GΩ
Surface Leakage Current	15μA	0.3μA
Temperature-Humidity Bias	Failed @500hrs	Passed @2000hrs

Field Performance (12-Month Monitoring)

• BER stability: Maintained <10⁻⁸ during monsoon season
• Maintenance cost: Reduced by ¥380,000/year
• System uptime: Improved from 92.1% to 99.97%

4. Technical Differentiation

▶ Multi-Barrier Moisture Protection

• Triple defense:
  1. Nano-ceramic fiber coating
  2. Hermetic via filling
  3. Hydrophobic conformal coating

▶ Vibration-Resistant Design

• 8-point screw fixation pattern (stress reduction >60%)
• Corner reinforcement with copper balancing

5. Client Benefits Achieved

✔ Zero unscheduled downtime in 18 months of deployment
✔ 72-hour rapid replacement guarantee (vs. 2-week industry standard)
✔ Full compliance with EN 50155 railway electronics standards

Certification & Testing:

• Passed IEC 60068-2-30 damp heat cyclic testing (6 cycles)
• MIL-STD-202G Method 106 immersion validation

Client Statement:
“KKPCB’s solution eliminated our chronic signal loss issues. Their boards outperformed all previous suppliers in tunnel environments.”
— Chief Maintenance Engineer, [Metro System Operator]

Request contact email address: [email protected]