JPH0110939Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a connection structure between electrodes and lead wires of a piezoelectric element or pyroelectric element made of a polymer film such as polyvinylidene fluoride.

Conventionally, a piezoelectric element or a pyroelectric element made of a polyvinylidene fluoride resin (hereinafter abbreviated as "PVDF") film and a lead wire have usually been connected to each other by directly applying a conductive paint to the element electrode. However, in the case of conductive paint, it has the drawback that it changes over time, and the connected parts may peel off, or even if it does not peel off, the conductivity changes, and it easily peels off when the lead wire is pulled. By the way, due to its nature, piezoelectric elements are used for purposes such as detecting stress applied to the piezoelectric element or converting stress by applying an electric signal to the piezoelectric element, and are not used in a static state. Furthermore, when pyroelectric elements are actually used, they are accompanied by vibrations and are rarely used in a static state. Therefore, there are many opportunities for these elements to exert forces on each other with the lead wires. Furthermore, even if there is no such opportunity, force is always applied when setting these elements into a device or connecting lead wires, so there is a high possibility that the lead wires will come off.

In addition to these circumstances, electrodes on these elements are generally formed by vacuum deposition or sputtering, but PVDF has a problem in that it has low adhesive strength with metal. Therefore, the polymer film is subjected to surface treatment such as acid or alkali treatment, corona treatment, etc. prior to electrode formation, but even with such surface treatment, the adhesive strength is still insufficient. Therefore, when force is applied to the lead wire, not only the bond between the lead wire and the electrode is broken for the reasons mentioned above, but also separation between the electrode and the PVDF often occurs.

The purpose of the present invention is to provide a new structure that simultaneously solves the above two problems. i.e. PVDF
An object of the present invention is to provide a structure in which the lead wires and electrodes are more difficult to peel off than the film even when an external force is applied to the lead wires of a piezoelectric element or pyroelectric element made of a polymer film such as the above.

By the way, piezoelectric elements or pyroelectric elements made of polymer films such as PVDF usually have a thickness of several microns to several micrometers.
The film is about 10 μm thick. Nevertheless, the inventor of the present invention found that if a hole is made in this, a new material made of solder, lead or tin is used, a rivet is provided, and the rivet head is formed with this material,
without damaging the electrode as with other materials.
Moreover, even though the material is soft, its structure is strong against external forces, and it can withstand even if the lead wire is connected to the rivet and an attempt is made to tear the lead wire and the element with considerable force, or even if an attempt is made to separate it due to vibration etc. We discovered this fact. A structure using such rivets has, of course, greater strength than a structure connected by conductive paint as described above, and even if it is easy to tear in the direction perpendicular to the stretching direction, such as a thin uniaxially stretched film, The strength is remarkable compared to conventional structures.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIGS. 1 and 2 show an embodiment in which lead wires are fixed to a PVDF element. In these figures, 1 is a film-like PVDF element, 2 and 2' are electrodes formed on both sides of the element 1, and 3 is an electrode that has been previously provided through the element 1 in the thickness direction in order to insert a rivet therethrough. 4 is a rivet attached to the hole 3; 5 is a lead wire for connecting the electrode 2 to an external circuit; and 6 is a low-temperature solder that connects the lead wire 5 to the rivet 4. The material used for the rivet 4 is tin, lead, or solder, which is a metal that can be welded to the solder 6 by low-temperature soldering. The PVDF element 1 is a polarized vinylidene fluoride homopolymer, a copolymer copolymerizable with vinylidene fluoride of 50 mol % or more, or a composition containing at least one of these as a main component. Note that the PVDF element 1 may be stretched before or at the same time as polarization, if necessary. Although not shown, one of the electrodes 2 and the metal rivet 4 may be further bonded by low-temperature solder or conductive paint to further ensure continuity between the two.

Further, in the embodiment, the end of the lead wire 5 is fixed to the rivet head, but for example, a conductive ring may be interposed between the rivet head and the polymer film 1.
The end of the lead wire 5 may be connected to this conductive ring. In that case, the electrode and the conductive ring may be further bonded by low-temperature solder or conductive paint to further ensure electrical continuity between the two.

As described above, the present invention involves forming a through hole in a piezoelectric or pyroelectric polymer film, attaching a rivet to the film through the through hole, and forming a rivet on both sides of the film. At least one of the electrodes is connected to a lead wire. Therefore, the lead wire is firmly connected to the film, increasing its strength.
Further, peeling of the electrode is also effectively prevented.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a main part of a piezoelectric or pyroelectric element showing a connection structure according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line .about. in FIG. 1. In addition, in the symbols used in the drawings, 1...
PVD element film, 2, 2'... electrode, 3... through hole, 4... rivet, 5... lead wire.

Claims (1)

[Scope of utility model registration request] A through hole in the thickness direction is formed in a film-like piezoelectric element or a pyroelectric element, which is made by forming electrodes on both sides of a polymer film having piezoelectricity or pyroelectricity, and through this through hole, solder, A connection structure between an electrode of a film-like piezoelectric element or a pyroelectric element and a lead wire, which is formed by attaching a rivet made of lead or tin and connecting at least one of the pair of electrodes and the lead wire with the rivet.