Wire connection technology of piezoelectric film sensor

Introduction

How to realize the reliable connection of the piezoelectric film is one of the most frequently asked questions by the customers. To this end, MSI company is very concerned about the development of the simplified connection technology of the piezoelectric film. Today, most of the sensors we offer to our customers are added to the lead. The purpose of this paper is to analyze and discuss the existing wiring schemes.

Some of the most convenient connection technologies require MSI to print certain electrodes on one side or two sides of the piezoelectric membrane, which can always be achieved in order to meet users' requirements in production. At the end of this article, a simple way to achieve the same effect is also provided. Generally speaking, in the fabrication of piezoelectric film sensor, screen electrode, conductive ink, metal mask, spray deposition or photo plate technology can be used for chemical etching.

target

What is considered here is the desired design goal for the lead connection method. No technology can be used to achieve all goals. The designer should identify the most important goals and select the appropriate connection scheme accordingly.

High conductivity / low resistance ~ unexpectedly, for most piezoelectric applications, the connection of high electrical conductivity is not a particularly important parameter. Piezoelectric sensors are often used in high impedance circuits, and several ohmic resistances in this type of circuit do not usually affect performance. However, it is more important that it is stable, that is, in use, the resistance should not fluctuate, because it will introduce an electrical noise source.

Low mass ~ when the piezoelectric film is attached to the mechanical support structure is particularly important. The sound effects produced by mechanical vibration on the mass of the joints on a flexible structure are astonishing.

Many applications of a small section of a piezoelectric film come from its low thickness, and the use of large terminals to impede this length is usually prohibited. If the piezoelectric film, including the connector, can not be attached to the contact surface, the contact vibration sensor may have different resonance. Compliance - this is also a characteristic that must be consistent with the flexibility of the piezoelectric film. A certain degree of flexibility has advantages in many applications.

Small area of the good piezoelectric device is likely to be used as a "point" acceptor. The effective working area of small piezoelectricity (the top and lower guide electrodes completely overlaps) can be made into a biased or unopened lead connection pad. The upper and lower weld pieces are separated from each other and are relative to each other (in the direction of thickness). In this way, the effective area (overlapping electrode) that is precisely defined can be induced to the distant connection point by the non piezoelectric conductive figure (stagger pin), which is the technology commonly used for "small" devices.

Where the mechanical strength ~ sensors most often bear the maximum stress near the connection point, some are accidental (pluggable cables), some of which are created by the design. In a word, the connecting method of the hollow rivet or solid rivet through the piezoelectric film has the best ability to resist strain. In order to improve the strength of the penetration connection, usually the lead connection points are strengthened with polyester chips.

Long-term stability ~ including all the common environmental parameters. Most of the connectors have very long life (pressing terminals, hollow rivets and conductive rubber joints, etc.). Other limited storage life (conductive adhesive).

This is particularly important when the production of simple and simple p