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How to solder piezo element?

Views: 50     Author: Site Editor     Publish Time: 2022-04-15      Origin: Site

Piezoelectric element refers to the use of piezoelectric technology in the transducer, indicator or as an independent device to produce audible devices. Piezoelectric element is a very sensitive device, its response time is only sub millisecond, which is much shorter than the blink time. When welding pins to piezoelectric elements, great care must be taken to prevent damage to the device.

Piezoelectric element

What is the working principal of a piezo element?

How to solder piezo element?

What should be paid attention to when soldering piezo element?

What is the working principal of a piezo element?

Piezoelectric elementsare an alternative electronic component that periodically changes its size in different fields. Generally, the frequency at which the element vibrates in response to current input plays a role in converting electrical energy into mechanical energy, which is determined by the physical composition and shape of a given material. When the cycle frequency of the piezoelectric element increases, the vibration of the element also increases. This frequency is called the resonance frequency. This is based on the fact that piezo elements have multiple uses in various departments.

Frequency is undoubtedly one of the characteristics of high-quality piezoelectric elements. In this function, we can infer that the perfect combination of frequencies is the main factor when generating sound pressure, which means that the plastic housing and piezoelectric bender should have matching frequencies.

Single crystal often used in piezoelectric speakers. The thin piezoelectric element is combined with the metal plate. When the piezoelectric element expands and contracts in a plane, warpage occurs because the size of the joined metal plates remains the same. Use the vibration and displacement generated by the voltage applied to the piezoelectric element.

Bi-crystals is a structure in which two piezoelectric elements are bonded together. This is used to obtain a larger displacement. When a differential voltage is applied to each of the two piezoelectric elements, the directions of expansion and contraction are opposite, causing warpage. By taking advantage of the fact that the tip is displaced, the cantilever structure can be used as a positioning element.

Stacked use displacement in the thickness direction, a large number of piezoelectric elements are stacked in a rod shape.

How to solder piezo element?

In practical applications, there are more than one chip constituting the piezoelectric sensor because the output charge of a single chip is very small, two or more chips being often bonded together. There are two bonding methods, namely connect in parallel or in series.

Parallel connection: The negative charge of the two piezoelectric elements is concentrated on the middle electrode, and the positive charge is concentrated on the electrodes on both sides. The piezo transducer has a large capacitance, a large output charge, and a large time constant, which is suitable for measurement slow-changing signal and charge output signal.

Connection in series: The positive charge is concentrated on the upper board of piezo element, while the negative charge is concentrated on the lower board of piezo element. The piezo transducer itself has small capacitance, fast response, and large output voltage, which is suitable for measuring signals with voltage as the output signal and higher frequency. The positive and negative charges at the bonding between the two piezoelectric plates are neutralized.

The steps of soldering pins to piezo element are as follows:

1. Pre heat soldering iron to 300º C max (572º F).

2. Strip wire approximately 5/32” and tin the lead with the solder.

3. Apply a small pool of liquid flux near the outer edge of the ceramic surface of piezo element. Add small dot of solder with soldering iron for maximum 0.5 seconds.

4. Lay the tinned wire on the solder dot and position the wire for desired orientation.

5. Apply soldering iron to the wire and solder connection for no more than 0.5 seconds (few seconds for metal surface) and reflow the solder onto the wire to complete the solder joint. Do not add additional solder unless the wire strands are not adequately covered with a film of solder.

6. Repeat this procedure for all other connections including the metal substrate of the bender. Try to keep all connections close together and observe the same lead lay.

7. Clean the flux off all connections with standard alcohol.

8. Visually examine each joint. The solder connection should be smooth and bright with no cracks or crazing.

9. Discard the bender if the joint on the ceramic fails by lifting off the silver coating of the bender. DO NOT solder to another spot on the ceramic surface - the performance and life of the bender will be degraded. The metal connection can be resoldered as required.

What should be paid attention to when soldering piezo element?

Piezoelectric element is a very sensitive device, its response time is only sub millisecond, which is much shorter than the blink time. When welding pins to piezoelectric elements, great care must be taken to prevent damage to the device.

The meaning of welding is to make reliable contact between electronic components and printed circuit board, and reduce the contact resistance to the minimum. Therefore, before welding, the oxide layer and dust on the surface of piezo element must be cleaned, and the temperature of the part to be welded should be balanced as far as possible. It is better to use flux without corrosion.

The overheating of electric soldering iron, long welding time and too much soldering tin will cause the copper coating on the circuit board to curl up. When welding, the temperature of the soldering iron should not be too high, and the welding time should be as short as possible. The quality of welding depends on whether the welding surface is clean or not. If it is clean and coated with flux, the welding will be fast and firm. The welding surface can be polished with fine sandpaper, and the flux shall be applied immediately after polishing to prevent reoxidation.

Learning something about piezo elements can help you know the working principal of piezo elements and how to solder piezo elements. If you want to buy high-quality piezo elements with reasonable price, Kailitech Company can provide you with the best products, as well as other piezo buzzers.


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