Surface-mounted Device (SMD) Piezoelectric Sounders: Precautions When Removing Foreign Objects with an Air Blower | Precautions for use of Sound Components

Guidelines concerning the mounted sounder

Applicable Series: PKMCS Series / PKLCS Series (SMD type)

Avoid the area near piezoelectric sounders when using compressed air to blow away foreign objects.

The sound pressure may drop or the sound may stop due to deformation of the piezoelectric diaphragm, cracks in the piezoelectric ceramic, or silicone breakage.

How the failure occurs

The inside of the surface-mounted device (SMD) piezoelectric sounder is divided into air chambers by a piezoelectric diaphragm and silicone adhesive. These air chambers are connected to the outside through the sound-emitting hole and open hole established on the top and sides of the product.

Due to this structure, if compressed air is blown into the piezoelectric sounder, air pressure may be applied to the piezoelectric diaphragm or lid. The following failures may then occur.

Deformation of the piezoelectric diaphragm	The state of the sound may change due to changes in the drive and vibration state of the piezoelectric diaphragm. That may interfere with normal operation.
Destruction of silicone holding the diaphragm	A leak may occur between the air chambers and the efficiency at which the sound is emitted may decline. That may then cause the sound pressure to drop or the sound to stop.
Damage of the piezoelectric ceramic	The sound pressure may drop or the sound may stop due to a reduction in the drive area of the piezoelectric diaphragm or the occurrence of a short circuit.
The lid may fall off	The air chambers may no longer be able form. The air pressure may then drop. (*This does not apply to the PKMCS1818 series.)

Cause

	PKLCS / PKMCS0909 Series	PKMCS1818 Series
Normal	*The sound emission hole / open hole of the PKMCS0909 are located in a position different than the above figure.
When air enters from sound emitting hole	Case and cover separate	Destroys silicone holding the diaphragm
When air enters from open hole	Destroys silicone holding the diaphragm