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Electrodes Piezoelectric ceramics are commonly supplied with silver electrodes
that are fused onto the surface at high Leads can be attached by soldering, and the following procedure is recommended: 1) Clean the electrode surface to be soldered by light abrasion with
a common pencil eraser to remove silver 2) Tin the lead with Sn-62 solder (62% tin, 36% lead, and 2% silver). 3) Dip the pre-tinned lead into a mild non-corrosive flux. 4) Melt a small quantity of the Sn-62 solder on the small tip of a soldering iron of approximately 30 watts. 5) Position the lead on the electrode area and press down with the soldering iron tip until the solder flows onto the electrode. Keep the duration of soldering time to a minimum (<5 seconds) to prevent excessive alloying of the silver electrode into the solder. Nickel Electrodes Also available are nickel electrodes that are applied by a low temperature electroless chemical deposition procedure. These nickel electrodes are much thinner than silver electrodes and have higher resistivity. They have specific advantages and are nearly always used on the faces of shear elements. They are applied to the faces perpendicular to the 1 axis of a plate that has been prepoled. This prevents depolarization that would otherwise occur with high temperature electrode application. Aging After polarization, most of the properties of piezoelectric ceramics begin a gradual change with time. These changes are very nearly logarithmic with time so it is convenient to express aging as a percentage change per time decade. The longer the period after polarization, or other event such as high temperature or stress exposure, the more stable the material becomes.
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