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Electrical Design Standard


Official Guidebolt Electrical-Design Standard


Required: all elements, RoHS-compliant (preferably RoHS3).

Preferred: all elements, REACH-compliant.

Preferred: all elements, halogen-free.

Preferred: all elements, flame-resistance UL94-V0.

Note that "X-Free" generally allows trace amounts below a standard threshold. For example, "halogen-free" and "zero halogen" are typically used interchangeably under the max 1500ppm of total halogens (IEC 61249-2-21).

Preferred: measurement standard, metric

Required: PCB build, fabrication-class IPC-2 (or better)


Preferred: all parts, automotive-grade (qualified to AEC-Q).

Required: all parts, temperature-range for operation and storage. See list below.

  • -40C to 85C (minimum)
  • -40C to 105C (acceptable)
  • -40C to 125C (good)
  • -55C to 150C (excellent)

Preferred: All power-connectors are glow-wire-capable.


Required: all PCBs, rounded corners.

Preferred: PCB rounded-corners, minimum radius 5mm.

Required: All PCBs have ENIG surface finish (or better).

Required: All parts are placed with at least 1mm spacing between parts.

Preferred: Fill to pad clearance, minimum 0.5mm

Preferred: PCB soldermask color, green.

Preferred: All signal PCBs are built with impedance control.

Required: All PCBs expected to endure high-moisture must have conformal-coating or encapsulation.

PCB Silkscreen

Required: Every PCB has the following silkscreen text (minimum). Refer to list below.

  • company name
  • part-number (with revision number)
  • batch number
  • part perimeter-outline (one per part)
  • part reference-designator (one per part)
  • functional-label (one per external-pin)

PCB Material

Preferred: All power PCBs have thermal conductivity of 0.7 W/mK (or better).

PCB Holes

Required: All THT holes have a minimum-diameter equal to maximum-lead-diameter + 0.25mm (IPC-2222 Level A).

Required: All THT annular-rings have a minimum-diameter equal to minimum-hole-dia + 0.7mm (IPC-2221 Level A).

PCB Vias

Preferred: standard sizes (hole-dia, annular-ring-dia).

  • 0.4mm, 0.8mm (small)
  • 0.5mm, 1mm (normal-compact)
  • 0.5mm, 1.2mm (normal)

Preferred: full-depth vias (normal plated-thru-hole, no blind or buried)

Preferred: no vias in pad

Preferred: via-hole-edge to pad-edge spacing, minimum 0.2mm

Preferred: via-hole-edge to via-hole-edge spacing, minimum 0.5mm

PCB Pads

Required: all pads, rounded corners

Required: pad rounded-corners, minimum radius 0.25mm

PCB Mounting

Required: all PCB-mounting-holes support metric screws

Preferred: All PCBs have at least 4 mounting holes.

Preferred: All PCB mounting holes are patterned as a simple shape (ex. square, rectangle).

PCB Board Edge Clearance

Required: board-edge to external-layer-conductor, minimum 0.25mm

Required: board-edge to internal-layer-conductor, minimum 0.5mm

Preferred: board-edge to any-layer-conductor, minimum 1mm

Required: board-edge to hole-edge, minimum 1mm

Required: board-edge to part-perimeter, minimum 1mm

Preferred: board-edge to SMT-part-perimeter, minimum 3mm


Required: All external pins have transient voltage protection.


Required: All electronics have at least 50K hours MTBF.

Preferred: All electronics have at least 150K hours MTBF.


Preferred: All MLCC capacitors have soft-terminated ends (bend-crack resistance).

Required: All high-value capacitors are aluminum-polymer type.