SU890459A1 - Film capacitor - Google Patents

Description

The invention relates to electronic engineering, in particular, to microelectronics associated with the manufacture of film capacitors (PCs) used in heat-resistant hybrid circuits for special devices operating in the temperature range from 20 to (250-300) s; Known PC, in KOTOpbix metallode. the cue electrode is deposited on a dielectric substrate, a dielectric layer is deposited on it, and the upper electrode is made of the same material, and the lower electrode til The disadvantages of such PCs are low reliability and a small percentage of the yield of suitable elements due to the fact that defects in the dielectric film leads to a decrease in the reliability of the capacitor or its complete breakdown. During long-term operation, especially in the temperature range of 250-300s, there is an intense diffusion of the electrode material into the dielectric, which also reduces the reliability and service life of the PC. The closest in technical essence to the invention is a thin-film capacitor, in which, after spraying the first electrode, this electrode is polished to reduce roughness, which increases the dielectric strength and reliability of E2 PC. The disadvantages of this PC are low reliability in operation in the temperature range from -60 to + 12ERs and the impossibility of operation at a BfcBfle temperature of 125 ° C, since polishing the lower electrode slightly reduces the diffusion of the electrode material. The purpose of the invention is to increase the reliability and heat resistance of the film capacitor. This goal is achieved by the fact that the electrode, made of a metal foil, is oxidized from the side adjacent to the dielectric film, and the thickness of the oxidized layer is 0.3-0.5 µm. The presence of the oxide layer between the dielectric film and the metal foil electrode prevents both the diffusion of the electrode material from the refractory metal sheet into the foil electrode and, conversely, under the action of temperature and the floor. The absence of diffusion in the proposed construction is due to the fact that an interlayer polarization effect occurs at the interface of two dielectrics, which drastically reduces the effect of the electric field and temperature, as a result of which directional diffusion between the electrodes is excluded.

The drawing shows the design of the proposed PC, where indicated:

1- electrode foil thickness

25-35 microns;

2- oxide layer with a thickness of 0.30, 5 microns;

3- deposited dielectric

film 0.3-0.5 μm thick;

4- thin film electrode from

refractory metal;

5- electrode pads

1, made of the same metal as the electrode 4 and obtained by photolithography;

6- dielectric substrate.

The proposed design of the film capacitor was tested under laboratory conditions during the manufacture and testing of an experimental batch.

The electrodes of the proposed PC, located on a dielectric substrate, are made of molybdenum or nickel films with a titanium underlayer. Molybdenum films are precipitated by ion-plasma sputtering of the target, nickel films are electron-beam evaporated from stebic, and titanium is precipitated by resistive evaporation from molybdenum boats. The thickness of the electrodes is 0.50, 8 microns. As a dielectric film, films with a thickness of 0.25-0.3 µm, obtained by ion-plasma reactive sputtering of silicon of the brand, are used. KEF-.80 or SijN films. 0.25–0.3 μm thick, obtained by ion9 plasma high-frequency sputtering of a target from fused quartz. A titanium or aluminum foil with a thickness of 25-30 µm is used for the other electrode. Oxidation of the foil at a depth of 0.3-0.5 µm is carried out by an electrolytic method in appropriate electrolytes with a controlled current to stop the oxidation process after reaching the specified thickness. Fastening of the electrode from the foil to the contact pads and combination

with a thin-film electrode of a tightly-melting metal is carried out in a specially designed device with electrode molding or an electrode system, such as in the manufacture of a capacitive matrix of two or more elements on a single substrate by laser and thermal compression welding. When the foil is oxidized, the areas adjacent to the contact pads are protected by a photoresist in order to avoid oxidation of these areas, as a result of which the welding process is impeded. Leucosapphire, polycore, sitall, or fotositall are used as substrates. The manufactured capacitors of the proposed construction are subjected to electrical tests in the temperature range of 20 -.

Using the proposed design of the capacitor significantly increases the reliability and heat resistance of the PC when it is used in the temperature range 20-300C. Economic effect: effect when using the proposed PCs in special equipment operating under extreme conditions

120 thousand rubles per year, since it eliminates the need for bulky and expensive cooling devices and increases the percentage

 output and durability of elements.

Claims (2)

1. The patent of Japan 51-38055, cl. 59 E 101.24, 10/19/76. 2. US patent 3533148, cl. 29-25.41, 19TO (prototype).