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PCB Clearance and Creepage Distance Table

igh voltage applications are where observing conductor clearance and creepage distances is critical

The process of designing electronic circuit boards in most cases is complex. To be efficient, engineers and designers must consider all three stages of PCBA development: design, manufacturing and testing. For example, when laying out the board choosing the best placement for components, traces and other conductive elements must be guided by DFM and DFA rules for manufacturing. Equally important is adhering to compliance testing requirements when required; like for reliable internal and external communication between USB devices. 

For high-voltage boards, safety must be added to the primary design considerations. High voltage TX/RX and/or high-power elements can create or attract currents at levels that can damage components, the board itself or even threaten nearby users. To combat these contingencies, there are specific PCB standards that define acceptable spacing between conductive elements. Knowing and following these PCB clearance and creepage distance table specifications is essential when designing high-voltage circuit boards.

Important Clearance and Creepage Distance Requirements

Not surprisingly, there are several industry standards that include specifications meant to ensure that PCBs and electronic devices are safe. Among these are IPC-2221, IPC-9592, IEC-6061 and IEC-62368. Each of these provides guidance and direction for placing components at distances to minimize the possibility of hazards; such as shorts and surface tracking. The most implemented of these are shown in the clearance and creepage distance tables below. 

PCB Clearance Distance Table 

For clearances, IPC-2221B is the prevailing standard and includes the specifications listed below.

PCB CLEARANCE DISTANCE TABLE

(Minimum Distances – mm)

Voltage (ACV or DCV)

Fabrication Boards

B1              B2             B3              B4

Assembly Boards

A5                A6                 A7

0-15

0.05

0.1

0.1

0.05

0.13

0.13

0.13

16-30

0.05

0.1

0.1

0.05

0.13

0.25

0.13

31-50

0.1

0.6

0.6

0.13

0.13

0.4

0.13

51-100

0.1

0.6

1.5

0.13

0.13

0.5

0.13

101-150

0.2

0.6

3.2

0.4

0.4

0.8

0.4

151-170

0.2

1.25

3.2

0.4

0.4

0.8

0.4

171-250

0.2

1.25

6.4

0.4

0.4

0.8

0.4

251-300

0.2

1.25

12.5

0.4

0.4

0.8

0.8

301-500

0.25

2.5

12.5

0.8

0.8

1.5

0.8

>500

0.0025 mm/V

0.005 mm/V

0.025 mm/V

0.00305 mm/V

0.00305 mm/V

0.00305 mm/V

0.00305 mm/V

The clearance distances above apply to conductors with the following attributes:

  •  B1  internal conductors
  •  B2  uncoated external conductors, up to 3050 m above sea level
  •  B3  uncoated external conductors, higher than 3050 m above sea level
  •  B4  polymer coated external conductors, at any elevation
  •  A5  conformal coated external conductors, at any elevation
  •  A6  uncoated external component leads/termination, up to 3050 m above sea level
  •  A7  conformal coated external component lead termination, at any elevation

PCB Creepage Distance Table

For creepage distances, IEC 60950-1 served as the industry standard for decades. However, many countries have adopted the more robust IEC 62368-1 for new product development. The intent of maximizing safety for users of electrical/electronic systems, especially for high-voltage applications, remains the primary objective and is reflected in the specifications below.

RMS Voltage 

(V)

PCBA CREEPAGE DISTANCE TABLE

(Minimum Distances – mm)

Pollution Degree

1

2

1

2

3

Material Group

Printed Boards

Other Materials

I, II, IIIa, IIIb

I, II, IIIa

I, II, IIIa, IIIb

I

II

IIIa, IIIb

I

II

IIIa, IIIb

25

0.025

0.04

0.125

0.5

0.5

0.5

1.25

1.25

1.25

32

0.025

0.04

0.14

0.53

0.53

0.53

1.3

1.3

1.3

40

0.025

0.04

0.16

0.56

0.8

1.1

1.4

1.6

1.8

50

0.025

0.04

0.18

0.6

0.85

1.2

1.5

1.7

1.9

63

0.04

0.063

0.2

0.63

0.9

1.25

1.6

1.8

2.0

80

0.063

0.1

0.22

0.67

0.95

1.3

1.7

1.9

2.1

100

0.1

0.16

0.25

0.71

1.0

1.4

1.8

2.0

2.2

125

0.16

0.25

0.28

0.75

1.05

1.5

1.9

2.1