Designer's Den - PCB Design Information

PCB Design Information.

Here is some useful information for designing general-use printed circuit boards. For other designs and materials, a good source for information is:

Design Standard for Rigid Printed Boards and Rigid Printed Board Assemblies
IPC-D-275
published by the
Institute for Interconnecting and Packaging Electronic Circuits (IPC)
7380 Lincolnwood Avenue
Lincolnwood, IL 60646

PCB Environment
PCB Base Material
Trace Width Calculator
Trace Spacing

Environmental Factors

The environment in which a PCB is to be used will change a number of factors needed to design and test it. The ambient temperature is one of these important factors.

Worst Case Environments
Cat	USE	Min Temp	Max Temp	Service
1	Consumer	0°C	+60°C	1-3 Yrs
2	Computer	+15°C	+60°C	~5 Yrs
3	Telecomm	-40°C	+85°C	7-20 Yrs
4	Civ Aircraft	-55°C	+95°C	~10 Yrs
5	Industrial	-55°C	+55°C	~10 Yrs
5	Auto Pass Cmp	-55°C	+55°C	~10 Yrs
6	Mil Gnd/Ship	-55°C	+95°C	~5 Yrs
7	Space	-40°C	+85°C	5-20 Yrs
8	Mil Aircraft	-55°C	+95°C	~5 Yrs
9	Auto Engine	-55°C	+125°C	~5 Yrs

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PCB Base Material

The base material a PCB is made of also affects it's design. Here are some examples materials.

PCB Base Laminate Data
Designation		Dielectric Thickness	Max Temp
ANSI	MIL-P-13949	Dielectric Thickness	Max Temp
-	PX	-	105°C
-	GE	-	125°C
FR-4	GF	.004-.014"	120°C
FR-4	GF	.015 +	130°C
FR-5	GH	.025-.054"	140°C
FR-5	GH	.055 +	170°C

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1 Oz. Plating, Internal Conductors
Width	10°C	20°C	30°C	45°C
.005"	200 mA	225 mA	250 mA	275 mA
.010"	400 mA	450 mA	600 mA	750 mA
.015"	550 mA	600 mA	750 mA	1.0 A
.020"	650 mA	700 mA	800 mA	1.2 A
.025"	750 mA	1.0 A	1.2 A	1.7 A
.050"	1.5 A	1.7 A	2.2 A	2.8 A
.100"	2.2 A	3.1 A	3.7 A	4.5 A
.150"	3.0 A	4.0 A	5.2 A	6.1 A

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Trace Spacing Guidelines

Conductor Spacing
Voltage Between Conductors (VDC or Peak)	Minimum Spacing (inches)
	Bare Board				Assembly
	B1	B2	B3	B4	A5	A6	A7
0 thru 15	.004	.025	.025	.005	.005	.005	.005
16 thru 30	.004	.025	.025	.005	.005	.010	.005
31 thru 50	.004	.025	.025	.005	.005	.015	.005
51 thru 100	.004	.025	.060	.005	.005	.020	.005
101 thru 150	.008	.025	.125	.015	.015	.030	.015
151 thru 170	.008	.050	.125	.015	.015	.030	.015
171 thru 250	.008	.050	.250	.015	.015	.030	.015
251 thru 300	.008	.050	.500	.015	.015	.030	.015
301 thru 500	.010	.100	.500	.030	.030	.060	.030
More than 500	.0001 /Volt	.0002 /Volt	.001 /Volt	.00012 /Volt	.00012 /Volt	.00012 /Volt	.00012 /Volt

B1 - Internal Conductors
B2 - External Conductors, uncoated, sea level to 10,000 ft.
B3 - External Conductors, uncoated, over 10,000 ft.
B4 - External Conductors, with permanent polymer coating (soldermask).
A5 - External Conductors, with conformal coating over assembly.
A6 - External Component lead/termination, uncoated.
A7 - External Component lead/termination, with conformal coating.

NOTE: This information is provided as a guideline only. All efforts have been made to ensure it is correct, but it is the responsibility of the user to verify the data is correct for their application.

Page Design by George Patrick) Last Modified: 10JUN02