If an electronic circuit, such as a microcontroller, is placed close to a relay noise generated by the relay may cause malfunctioning.
When designing printed circuit boards keep the trace runs as short as possible.
When the relay is mounted on a printed circuit board, use a board of 1 mm or more in thickness. If the printed circuit board is not thick enough, it may be subject to warpage which will add tension to the relay, causing variations in the relay characteristics. Since a particularly thin printed circuit board is flexible, it is necessary to solder near the root of the relay pins. Preliminary soldering of the pin root is often insufficient, since its solder is likely to become loose.
If a thermal cycle is applied to the soldered part, cracks may be generated in it. Special care is required for the relay location, base material and through hole shape.
Relay mounting position
The vibration resistance and shock resistance of a relay are greatly affected by its mounting position. It is particularly important to select the mounting position in order to prevent the break contacts from being instantaneously cut due to vibration or shock. The vibration resistance and shock resistance are at a minimum when the direction of vibration or shock is aligned with the operation direction of the armature (mobile iron piece) and contacts. If it is possible to anticipate the direction of vibration or shock, mount the relay so that the direction in which vibration or shock is applied is perpendicular to the direction of the relay armature operation. Fig. 10 shows the direction of relay armature operation.
Fig. 10 Direction of Armature Operation
Notes on mounting
When a relay is mounted using an automatic machine, note that application of excessive external force to the cover at the time of chucking or insertion, it may damage or change the characteristics of the cover and relay.
Temporary securing to printed circuit board
Avoid bending the pins to temporarily secure the relay to the printed circuit board. (Refer to Fig. 11.) Bending the pins may degrade sealability or adversely influence the internal mechanism. Pin bending may be allowed under certain conditions in the case of Miniature Signal Relays.
Fig. 11 Bending Relay Pins
Application of soldering flux
For an unsealed type relay, do not directly apply soldering flux to the relay.
The following conditions are recommended for soldering a relay onto a printed circuit board.
Automatic soldering: Flow solder is recommended
Preheating: 100°C max. 1 min. max.
Solder temperature: 250°C max.
Solder time: 5 to 10 seconds
Manual soldering (by soldering iron):
Solder temperature: 350°C max.
Solder time: 2 to 3 seconds
Ventilation immediately after soldering is completed is recommended.
Avoid immersing the board in cleaning solvent immediately after soldering; otherwise thermal shock may occur.
Pin cutting after soldering
Do not cut the pins of the relay with a revolving blade or an ultrasonic cutter. The vibration that is applied to the relay during cutting may change the relay characteristics.