2-layer PCB

2-layer PCB

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What is 2-layer PCB?

At FAST-PCB, we manufacture high-quality 2-layer PCBs that serve as the foundation for countless electronic products worldwide. With over 24 years of experience in the PCB industry, we deliver reliable double-sided boards that meet the demanding requirements of modern electronics while maintaining competitive pricing and fast turnaround times.

fastpcb 2-layer pcb

A 2-layer PCB (double-sided PCB) is a printed circuit board with conductive copper layers on both the top and bottom sides of an insulating substrate. These two layers are connected through plated through-holes (PTH), allowing electrical signals to pass between the top and bottom surfaces. This configuration provides significantly more routing space than single-sided boards while remaining cost-effective for a wide range of applications.

Structure of 2-Layer PCB

A typical 2-layer PCB consists of:

Top Copper Layer

  • Circuit traces and component pads on the upper surface
  • Typical thickness: 1oz (35μm) or 2oz (70μm)
  • Houses most components in standard designs
  • Connected to bottom layer through plated holes

Core Substrate

  • Insulating material, typically FR-4 fiberglass epoxy
  • Standard thickness: 1.6mm (0.062″)
  • Provides mechanical support and electrical insulation
  • Available in various thicknesses: 0.4mm to 3.2mm

Bottom Copper Layer

  • Circuit traces and pads on the lower surface
  • Same thickness as top layer
  • Often used as ground plane or additional routing
  • Can accommodate surface mount or through-hole components

Plated Through-Holes (PTH)

  • Copper-plated holes connecting top and bottom layers
  • Provides electrical connection between layers
  • Also serves as mounting points for through-hole components
  • Typical diameter: 0.2mm to 6.0mm

Solder Mask

  • Protective coating over copper traces
  • Prevents oxidation and accidental solder bridges
  • Available in multiple colors (green most common)
  • Exposes only pads for component soldering

Silkscreen

  • White or colored legends for component identification
  • Reference designators, polarity marks, logos
  • Helps with assembly and troubleshooting
  • Applied over solder mask

Structure of 2-Layer PCB

A typical 2-layer PCB consists of:

Top Copper Layer

  • Circuit traces and component pads on the upper surface
  • Typical thickness: 1oz (35μm) or 2oz (70μm)
  • Houses most components in standard designs
  • Connected to bottom layer through plated holes

Core Substrate

  • Insulating material, typically FR-4 fiberglass epoxy
  • Standard thickness: 1.6mm (0.062″)
  • Provides mechanical support and electrical insulation
  • Available in various thicknesses: 0.4mm to 3.2mm

Bottom Copper Layer

  • Circuit traces and pads on the lower surface
  • Same thickness as top layer
  • Often used as ground plane or additional routing
  • Can accommodate surface mount or through-hole components

Plated Through-Holes (PTH)

  • Copper-plated holes connecting top and bottom layers
  • Provides electrical connection between layers
  • Also serves as mounting points for through-hole components
  • Typical diameter: 0.2mm to 6.0mm

Solder Mask

  • Protective coating over copper traces
  • Prevents oxidation and accidental solder bridges
  • Available in multiple colors (green most common)
  • Exposes only pads for component soldering

Silkscreen

  • White or colored legends for component identification
  • Reference designators, polarity marks, logos
  • Helps with assembly and troubleshooting
  • Applied over solder mask

FAST-PCB 2-Layer Specifications

Board Specifications

  • Minimum size: 5mm x 5mm
  • Maximum size: 500mm x 600mm
  • Standard thickness: 0.4mm, 0.6mm, 0.8mm, 1.0mm, 1.2mm, 1.6mm, 2.0mm, 2.4mm
  • Thickness tolerance: ±10%

Copper Specifications

  • Copper weight: 0.5oz, 1oz, 2oz, 3oz, 4oz
  • Minimum trace width: 4 mil (0.1mm)
  • Minimum trace spacing: 4 mil (0.1mm)
  • Fine line capability: 3/3 mil available

Drilling Capabilities

  • Minimum hole size: 0.2mm (8 mil)
  • Maximum hole size: 6.0mm
  • Hole tolerance: ±0.075mm
  • Aspect ratio: Up to 10:1

Surface Finish Options

  • HASL (Hot Air Solder Leveling)
  • Lead-free HASL
  • ENIG (Electroless Nickel Immersion Gold)
  • OSP (Organic Solderability Preservative)
  • Immersion Silver
  • Immersion Tin

Solder Mask

  • Colors: Green, red, blue, white, black, yellow, matte black
  • Minimum clearance: 3 mil (0.076mm)
  • Dam height: 10-20μm
  • Solder mask over bare copper (SMOBC)

Silkscreen

  • Colors: White, black, yellow
  • Minimum line width: 6 mil (0.15mm)
  • Minimum text height: 0.8mm
  • Position tolerance: ±0.1mm

Quality Standards

  • IPC-A-600 Class 2 or Class 3
  • IPC-6012 qualified
  • 100% electrical testing available
  • AOI (Automated Optical Inspection)