SU928431A1 - Method of manufacturing glass-ceramic capacitors with aluminium electrodes - Google Patents

Description

(54) METHOD OF MANUFACTURING GLASS-CERAMIC CONDENSERS WITH ALUMINUM ELECTUDES

This invention relates to electronic engineering and can be used to make multilayer glass-ceramic capacitors with non-precious metal electrodes.

A known method of manufacturing multilayer capacitors with a glass-containing dielectric, sintering at a temperature below 600 ° C, in combination with a non-precious metal electrode 1.

The disadvantage of this method is the complexity of the process.

The closest in technical essence to the present invention is a method of manufacturing glass-ceramic capacitors, including preparing a heterogeneous mixture of fine powders of inorganic glass and ceramics, cutting aluminum foil, forming a dielectric on aluminum foil, group assembly of multilayer packages, followed by hot pressing and cutting into individual blanks 21 .

The disadvantages of this method are low specific characteristics of manufactured capacitors, low electrical strength.

The aim of the invention is to expand the range of nominal capacities and operating voltages and simplify the technology.

The goal is achieved by the fact that, according to the method of manufacturing glass-ceramic capacitors with aluminum electrodes, including the preparation of a heterogeneous mixture of gonx-finite powders of inorganic glass and ceramics, cutting aluminum; foil, forming dielectric on aluminum foil, group assembly of multilayer packages followed by hot pressing and cutting on separate blanks, gluing aluminum foil onto a polyester tape, forcing a dielectric in the form of a 15-1500 µm thick film by casting slip on aluminum foil, after which it is made air drying and removing lavsan substrate; and carry out a group assembly of multilayer packages, followed by their heat treatment at a temperature of 420-550 ° C and a specific pressure of 60-140 kg / cm. The essence of the method is as follows. From a glass-ceramic composition with an inorganic binder, 5–15 µm thick, cut directly in the form of a comb — a group of combined teeth of different width — onto an aluminum foil — and. pasted on mylar tape, cast film, the thickness of which can vary from 15 to 500 microns. After air drying for 10- 60 min, the lavsan substrate is separated, and a two-layer film (dielectric-aluminum electrode) is cut into plates, from which multi-layer capacitor packages are collected, which are then subjected to sintering at 420-550 ° C (depending on the content the ceramic component in the composition) and the specific pressure of 60140 kg / cm After sintering (the envelope package is cut into separate capacitive elements of the workpiece. During the sintering process, the glass melts and wraps the ceramic particles into a monolithic block The residual porosity of the material does not exceed 6%. Uniform pressing across the entire working area of the dielectric eliminates the formation of areas with increased porosity and the presence of microcracks, which makes it possible to increase the working voltage gradient by 1.5–2 times and, consequently, reduce the dielectric thickness and increase the maximum and specific capacitance of the capacitor.The compaction of the dielectric structure leads to an increase in the moisture resistance and operational reliability of the capacitor package. Thus, the proposed method provides for obtaining glass-ceramic capacitors with aluminum electrodes and an extended range of capacitances and operating voltages, with enhanced moisture resistance and operational reliability. Using aluminum foil of small thickness, simplifying the operation of moisture protection, connecting the operation of fusing a dielectric layer to an aluminum elec- trure will reduce the consumption of materials and the complexity of such capacitors. For the manufacture of high-frequency condensers of the TKE M75 group, use is made of TL / -75 ceramics (lantate aluminate and calcium titanate solid solution), lead brochure and SKE-5 fusible lead-borate glass. These materials are crushed to a specific surface area of 8000-10000, mixed in a predetermined ratio with each other and with polyvinyl butyral binding to a slip state with a viscosity through an OT-4 funnel for 25 ± 5 s. The slip through the spinneret is poured onto a moving cutting of aluminum foil glued onto a polyester tape. The thickness of the resulting film is determined by the width of the die and the speed of the tape substrate. After air drying and separating the polyester substrate, the two-layer film is cut into plates containing a certain number of teeth — capacitor billets for multilayer packets, followed by their heat treatment according to the following mode: heating to 420-550 ° C at a rate of 818 C / min; pressing at a pressure of 60140 kg / cm for 1-1.5 minutes. The thickness of the dielectric film after heat treatment is 60% of the thickness of the air-dry film. Example 1. For cutting aluminum foil, designed for manufacturing a group of capacitors of 2x2 mm in size and glued, for example, with a 12% polyvinyl butyral solution, to a base, a 330-micron-thick ceramic film is cast, dried in air and cut into plates, then produced an assembly of three layers of a block of capacitor packs that is heat-treated according to the mode: heating to 530 + 10 ° С at a rate of 10 ° C / min; pressing at a pressure of 100 kg / cm. within 1 min. After dividing the block into blanks and designing the contact unit, the resulting capacitors have the following characteristics: capacitance C 10 + pF, dielectric loss tangent tg (f 14-16 insulation resistance. 10 Ohm. Example 2. For cutting aluminum foil, designed to produce a group of 10 x 10 mm condensers and glued, for example, 12% polyvinyl butyral solution onto a polyester base, a 45 micron thick glass-ceramic film is cast, the block assembly of 30-layer capacitors is assembled, which is heat-treated mode: heating up to 540 ± 10 ° С at a rate of 15 ° C / min; pressing at a pressure of 120 kg / cm for 1 min. After cutting the block into blanks and making a contact pin, the resulting capacitors have a capacity

From 40000-45000 pF, tg6. 10 15-18, Ohms.

Capacitors are operable in the range of telesheratures from - to + 85C with a voltage of 50 V.

Table shows the comparative characteristics of the capacitors.

As follows from the table, the proposed method makes it possible to obtain glass-ceramic capacitors with aluminum electrodes with an extended scale of nominal capacitances of the operating voltages, with a 1.7 times higher capacity, more moisture resistant than the known capacitors.

Claims (2)

1. US patent N "3020456, cl. 317-258, 6.02.62. 2. USSR author's certificate N 333876, 15 cl. H 01 G 4/20, 1968 (prototype).