Brochure

24
Technical Information – Relays
PCB Thickness
PCBs having a thickness of 0.8, 1.2, 1.6, or 2.0 mm are generally
used. A PCB that is 1.6 mm thick is best for mounting a PCB relay,
considering the weight of the relay and the length of the terminals.
(The terminal length of OMRON relays is 3, 3.5, or 4.0 to 5.0 mm.)
Terminal Hole Diameter and Land Diameter
Select the appropriate terminal hole and land diameters from the
following table, based on the PCB mounting hole drawing. Land
diameters may be reduced to less than those listed below if the
through-hole connection process is to be employed.
Terminal Hole and Land Diameters
Shape of Lands
The land section should be on the center line of the copper-foil
pattern, so that the soldered fillets become uniform.
A break in the circular land area will prevent molten solder from
filling holes reserved for components which must be soldered
manually after the automatic soldering of the PCB is complete.
Conductor Width and Thickness
The following thickness of copper foil are standard: 35 µm and
70 µm. The conductor width is determined by the current flow and
allowable temperature rise. Refer to the chart below.
Conductor Pitch
The conductor pitch on a PCB is determined according to the
insulation resistance between conductors and the environmental
conditions under which the PCB is to be placed. The following
graph shows the general relationship between the voltage
between conductors and the conductor pitch on a PCB. However,
if the PCB must conform to safety organization standards (such
as UL, CSA, VDE, etc.), priority must be given to fulfilling their
requirements.
3.5
Break in land
0.2 to 0.5 mm
Item Epoxy Based Phenol-based
Glass Epoxy (GE) Paper Epoxy (PE) Paper Phenol (PP)
Electrical characteristics
Mechanical characteristics
Cost Effectiveness
High insulation resistance.
Insulation resistance hardly
affected by humidity.
Little expansions/shrinkage
caused by change in
temperature or humidity.
Suitable for through-hole PCBs
and multi-layered PCBs.
Fair Much expansion/shrinkage
caused by changes in
temperature or humidity.
Not suitable for through-hole
PCB.
Expensive Fair Fair
Fair Insulation resistance degraded
by humidity.
Correct
Incorrect
Conductor Width and Carry Current
(according to IEC Pub326-3)
Sectional area
(mm )
Allowable current (A)
Conductor width (mm)
Temperature rise value
100°C
75°C
50°C
40°C
30°C
20°C
10°C
0.03 0.05 0.07 0.1 0.3 0.5 0.7
610 g/m
70 mm
305 g/m
35 mm
2
2
2
Terminal Hole Diameter Minimum Land Diameter
Normal Tolerance
0.6 mm ±0.1 mm 1.5 mm
0.8 mm 1.8mm
1.0 mm 2.0mm
1.2 mm 2.5mm
1.3 mm 2.5mm
1.5 mm 3.0mm
1.6 mm 3.0mm
2.0 mm 3.0mm
Omron A5 Catalogue 2007 1-282 11/9/06 10:16 am Page 24