PCB Assembly Service of Network and communication Devices

Network and communication equipment circuit boards need to achieve "zero failure" in scenarios such as ultra high speed signal transmission, extreme heat dissipation requirements, and 7 × 24-hour uninterrupted operation. Through high-frequency materials, precision impedance control, multi-layer heat dissipation architecture, and full dimensional reliability verification, they ensure the long-term stable operation of equipment in key areas such as 5G, data centers, and core networks.

Core principles：

• High frequency performance (low loss/precise impedance)
• High density (HDI/microporous technology)
• High reliability (anti vibration/moisture resistance)
• Fully shielded (EMC/EMI suppression)
• Full certification (industry mandatory standard)
• Low insertion loss (signal path optimization)
• Low noise (power and ground isolation)
• Strict craftsmanship (sub micron machining accuracy)

Network and communication equipment (such as routers, switches, 5G base stations, optical transmission equipment, etc.) need to meet strict requirements in terms of high-frequency signal integrity, heat dissipation, long-term stability, and high-density interconnection. The following are the areas we focus on in the production and assembly process:

1. Integrity of high-frequency signals

• High frequency substrate selection:

Using low dielectric loss substrates (such as Rogers RO4000 series, Taconic RF-35), with a dielectric constant (Dk) tolerance of ± 0.05 (@ 10GHz) and a loss tangent (Df) ≤ 0.003.

Multi layer board hybrid compression structure (such as FR4+high-frequency material) reduces the transmission loss of high-speed signal layers (such as 56Gbps SerDes).

• Impedance control and wiring:

Differential impedance control accuracy is ± 5% (100 Ω± 5 Ω) to avoid signal reflection (such as PCIe Gen5, 400G Ethernet).

The RF wiring adopts coplanar waveguide (CPW) or strip line structure to avoid crossing the dividing reference plane.

Back Drilling process: Remove excess copper column stubs and reduce high-frequency signal resonance (stub length ≤ 1/10 of signal wavelength).

2. High density interconnection and advanced packaging

• HDI and Microporous Technology:

O Use any layer interconnect (Any layer HDI), blind/buried hole diameter ≤ 0.1mm, interlayer alignment accuracy ± 25 μ m.

The solder pads are formed using SMD (laser direct molding) or mSAP (modified semi additive method), with a line width/spacing of ≤ 30 μ m.

• High speed connector integration:

O Supports QSFP-DD/OSFP interfaces (400G/800G optical modules), impedance matching ± 3%, insertion loss< 1dB@28GHz .

The board to board connector adopts elastic contact (Pogo Pin) or LGA (Grid Array) packaging, with a plug-in life of more than 10000 times.

3. Heat dissipation and power management

• High thermal conductivity design:

The substrate is embedded with a metal core (aluminum/copper) or ceramic filled resin (thermal conductivity ≥ 3W/m • K) for FPGA/ASIC heat dissipation.

Fill the bottom of key heating elements (such as CPU, optical module) with thermal conductive silicone grease (thermal resistance<0.1 ℃• cm ²/W) or phase change material (PCM).

• Optimization of heat dissipation structure:

Multi layer board design with a heat dissipation through-hole array (aperture 0.3mm, spacing 1mm) to enhance vertical thermal conductivity.

Surface mounted heat dissipation fins or vapor chambers with power density support greater than 50W/cm ².

4. EMC/EMI protection and grounding design

• Electromagnetic shielding:

Sensitive areas are covered with conductive shields (Can Shield) or absorbing materials (ferrite/carbon based composite materials) to suppress radiation noise.

The power module adopts a π - type filtering circuit (TVS+magnetic beads+capacitor), which has passed the IEC 61000-4-5 (surge 4kV) test.

• Layered grounding strategy:

Divide digital ground, analog ground, and RF ground, and connect them through magnetic beads or 0 Ω resistors to isolate noise coupling.

The 20H rule for multi-layer boards (with a 20 fold reduction in layer thickness within the power layer) reduces edge electromagnetic leakage.

5. High reliability manufacturing and testing

• Precision machining technology:

Laser drilling accuracy ± 15 μ m, aperture tolerance ± 5%, to avoid material delamination caused by mechanical stress.

Gold/silver immersion surface treatment (thickness>1 μ m) to ensure the oxidation resistance of high-frequency solder joints (storage life>12 months).

• Rigorous environmental testing:

Temperature cycling test (-40 ℃) ↔+ 125 ℃, 1000 cycles), verify the fatigue resistance of solder joints (crack length<10%).

Wet heat aging test (85 ℃/85% RH, 1000 hours) to ensure insulation resistance>10G Ω.

Vibration test (20Grms, frequency 5-2000Hz), in compliance with NEBS GR-63-CORE (Seismic Standard for Telecommunications Equipment).

6. Standards and Certification Requirements

• Industry compliance:

Through standards such as Telcordia GR-468 (Optical Module Reliability) and 3GPP 38.104 (5G Base Station RF Performance).

Safety certification: UL 60950 (Information Technology Equipment), IEC 62368-1 (Audio Video and Communication Equipment).

• Data security: