JPS6155242B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a polymer film for electrets, and an object of the present invention is to easily and strongly fix a polymer film for electrets to the surface of a metal plate.

Conventionally, methods of fixing a polymer film to a metal plate include 1) adhering using an adhesive, and 2) thermally bonding or thermally fusing the polymer film with a heat press hot roll, etc. There is. However, in method 1, polymer films suitable for electrets, such as fluororesin films, are not suitable for adhesion and have weak adhesive strength, so the metal plate to which the film is glued is cut into electrodes for microphones, etc., and formed by cutting, press punching, etc. It is difficult to process and is not suitable for mass production, and when it is made into an electret, the adhesive deteriorates the characteristics of the electret, resulting in poor stability and reliability. In addition, when using method 2 to thermally bond or fuse a polymer film to the surface of a metal plate, large-scale equipment such as a heat press and heat roller is required, and the baked state of the film may be uneven due to uneven pressure and temperature distribution. becomes. In particular, it is difficult to accurately control the cooling rate during the cooling process after baking due to constraints on manufacturing equipment, so if the orientation of the film's molecular arrangement is disrupted and crystallization occurs, uniform crystals may not be obtained and It lacks stability and reliability when the polymer coating is made into an electret.

The present invention provides a manufacturing method for fixing a polymer film for an electret to an electrode using simple manufacturing equipment by eliminating these conventional drawbacks.

An embodiment of the present invention will be described below with reference to the drawings. 1 is a hot plate; 2 is a metal plate coated with a polymer layer 3; 4 is a heater for heating the hot plate 1;
5 is a polymer film, 6 is a flat plate, and 7 is a heat insulating layer.

Now, the metal plate 2 is adsorbed onto the hot plate 1 by vacuum chucking or the like, and heated by the heater 4 until the polymer layer 3 on the metal plate 2 becomes molten. After that, the polymer film 5 is held under tension and separated from the polymer layer 3, and a well-polished flat plate 6 with a heat insulating layer 7 is pressed onto it to make it adhere to the polymer layer 3. After that, the flat plate 6 is removed and the polymer coating is applied. Fusion is carried out at a temperature that does not decompose. The flat plate 6 used to adhere the polymer film 5 to the polymer layer 3 may also be a roller having a heat insulating layer. In addition, in the above process, a film can be obtained by the same process even without the polymer layer 3 between the polymer film 5 and the metal plate 2, but the fixing strength is weak and the surface state of the metal plate 2 is made of polymer. Since it inhibits uniform crystallization of the film, it lacks stability and reliability after electrification.

The polymer coating for electrets fixed to the surface of the metal plate through the above steps has the following characteristics.

1. Since it is tightly attached to the metal plate 2 with the polymer layer 3 interposed, it is strongly fixed and can be formed into fixed electrodes for microphone earphones, speakers, etc. by cutting, press punching, etc.

2. It is strongly adsorbed to the hot plate 1 by vacuum chucking, etc., and there is less temperature unevenness compared to hot presses, hot rollers, etc., so a uniform coating can be obtained. Furthermore, since the metal plate temperature and the hot plate temperature are approximately equal, temperature control is easy. In particular, during cooling, since the cooling rate can be easily controlled, the crystallization of the coating molecules can be controlled, and the stability and reliability of the electret can be improved.

3. Since the polymer film 5 is kept at a high temperature away from the surface of the metal plate 2 to be fused, the adsorbed gas on the surface of the film 5 escapes, resulting in a smooth coating surface without air bubbles, which is highly stable and reliable for electrets. It becomes a polymer film.

4. Compared to hot presses, hot rollers, etc., the structure of the jig does not require a pressurizing device, so it can be made easily, and a coating for electrets can be obtained at a low cost.

As explained above in the examples, according to the present invention, a uniform polymer coating can be firmly fixed on the surface of a metal plate of an appropriate area using a jig with a simple configuration, so it can be pressed onto fixed electrodes of microphones, headphone speakers, etc. Alternatively, it can be formed by cutting, and if flatness is required, a flat pressing process can be added after molding to obtain the specified flatness, especially for small microphones, earphones, etc.
Small-area fixed electrodes can be supplied at low cost and with good yield. Further, for electrodes having a relatively large area, a coating can be formed by the same process after electrode molding.

[Brief explanation of the drawing]

The drawing is a process diagram of a method for manufacturing a polymer coating for electrets according to an embodiment of the present invention. 1... Hot plate, 2... Metal plate, 3... Polymer layer,
5...Polymer film.

Claims (1)

[Claims] 1. A metal plate having a polymer layer is adsorbed on a hot plate having a large heat capacity, a polymer film is held at a distance from the polymer layer, and the polymer layer is melted by heating with the hot plate, and then the 1. A method for producing a polymer coating for an electret, which comprises bringing a polymer film into close contact with the polymer layer and fusing the polymer film to the metal plate.