DD153308A1 - PROCESS FOR PRODUCING COATED SUBSTRATES FOR THICK-CIRCUIT CIRCLES - Google Patents

Abstract

The object and the object of the invention is the economically feasible production of coated substrates with improved properties for thick film technology. The Alind2Oind3 coated substrate for thick-film circuits is according to the invention in an aqueous alkali-free electrolyte preferably of the composition 0.3-0.6 m NHind4F; 0.4-0.8 m (NHind4) ind2COind3; 0.3-0.6 m (NHind4) ind3POind4 with and without additions of amines produced by anodic oxidation under spark discharge, is alkali-free, good electrical insulating, good heat-conducting and adhesion-promoting. The Alind2Oind3 layer, which adheres to the base material, is deposited on aluminum or alloys, aluminum-iron composites or made of aluminum oxide-hydroxydic compounds based on iron or alloys. On the coated substrate, the circuit can be applied on both sides. The substrates thus produced are economically acceptable solutions. Such thick film circuits on Alind2Oind3 coated substrate material find use, e.g. in electronic consumer goods and in medical technology.

Description

Process for the preparation of coated substrates for thick film circuits

Field of application of the invention

The invention includes a process for making coated substrates for thick film circuits having improved electrical isolation, thermal, and mechanical properties. Such thick film circuits on coated substrate material find use, for example, in consumer electronics and medical technology

Characteristic of the known technical solutions

It is known that thick-film circuits on high-purity AloO-. - Produce ceramics, as described for example in DE - AS 1690255. The disadvantages are that the corresponding heat loss is derived insufficiently over the substrate material. Furthermore, this' solution raises economic Problerne, - because the cost of production of the ALPO, ~ ceramic is very high ₀ - To this .Nachteile eliminate were enameled steel substrates in the invention applications US as - PS 3,809,797 and DB - Although the enamelled steel substrate has good heat conduction, it has disadvantages with respect to the substrate waveguide and the adhesive strength of printed circuit structures. In the patent applications US Pat. No. 3,638,506, CH-PS 518048 and AT- PS 297628 is used as substrate material anodic

used aluminum whose aluminum oxide layer is very porous, "....

The anodizing of Mob is described in the patent application US Pat. No. 4,075,756. The resulting FD ₂ O ₁ - layer is very dense and has favorable properties for this use. However, this method is to be rejected for economic reasons.

Aim of the invention. '

It is the object of the invention to eliminate these disadvantages and to produce an economically acceptable coated substrate for thick film circuits with improved properties.

Explanation of the essence of the invention

The invention has for its object to produce a coated substrate for thick film technology. According to the invention the object is achieved in that on aluminum or · alloys or iron or ₀ alloys an alkali-free, p © renarme, electrically highly insulating, adhesion-promoting AIPO, -.. Layer is applied on 'which are imprints the circuit "By Using metal as a substrate material dissipates the heat loss of the operating circuit quickly. It has been found that coated substrates produced in this way can be printed on both sides due to the very good adhesion of the applied oxide layer and the metal, which is an advantage of the process.

On aluminum or alloys, the application of the AlpO-3 - layer in an aqueous electrolyte by anodic oxidation under spark discharge according to DD - WP 142360 "According to the invention an alkali-free aqueous electrolyte is preferably the Zusammenzu tzu.ng O ₄ 3 ~ O ₅ . 6 m MiJP; 0.4 0> 8 π) (UH ₄ ) J ₂ CO ₃ ; O ₅ 3 - 0.6'ra (NH.) "PO. with and without additions of amines, in particular methyl, ethyl and / or ethanolamines up to the saturation concentration.

- 3 - "223858.

The working voltage is> 170 V ", the coating,? - current density at 4 A / dm«

The coated substrates obtained have a white, porcelain-like appearance and are not only favorable in their thermal conductivity and electrical insulation properties, but on the same side also a very good primer for circuits to be printed o. ·

The anodic oxidation of the aluminum under spark discharge can also with the inventive electrolyte in a 'aluminum - iron - Composite be performed * The obtained Al ₂ O., - layers are well adherent and hafVermittelnd to be printed circuit good thermally conductive and electrically insulating.

On iron or alloys, a deposition of aluminum oxide or aluminum hydroxide components from an aqueous aluminate electrolyte according to DD - WP 142359 is carried out before the anodic oxidation under spark discharge.

However, these layers obtained are still highly hydrous and insufficiently suitable as a substrate for thick-film circuits. "Wake an intermediate treatment of the thus coated substrates in deionized water is a 'spark discharge carried out in your inventive electrolyte. As a result, the aqueous layer constituents are dehydrated and compacted adherent to the Sisenoberfläche. The coated substrates obtained in this way have an off-white appearance, have a good heat conductivity and electrical insulation behavior and are a good primer for printed circuits β

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Embodiment "·

The invention will be explained below on three "embodiments"

Embodiment 1

A substrate of Al 99 »5 is pickled bare and then in an electrolyte consisting of 0.5 m NH ₄ F; 0.5 m (EH ₄ ) ₂ CO ₃ ; 0.5 m (M ₄ ) OPO ₄ and 0.01 m trieth-

nolamin at a voltage of 180 Y and a current density

2 of 4 A / dm anodically coated in an electrolytic cell. The temperature of the electrolyte is 25 ^° C. After the anodic oxidation is ended by spark discharge, the coated substrate is removed from the electrochemical cell, good rinsed with deionized water and dried.

The coated substrate thus produced can be printed on both sides with circuits.

Embodiment 2

An iron substrate coated with aluminum on all sides is electrolytically sputter-coated in the electrolyte as described in Embodiment 1 at a current density of 3 A / dm. The obtained coated substrate is well rinsed in deionized water and dried, and is printable with thick film circuits

Embodiment 3

A steel sheet (StTZu) is pickled bare metallic and then in an aqueous solution of ca "O ₃ 45 ni Aluminat'j about 0.17 m citric acid; ca '' delte 7.5 x 10 "^ m gluconate anodically behan- at 25 ⁰ C in an electrolytic cell. The DC voltage is continuously from 0« 75 V

V-5-2 2 3858

with a tension feed rate of preferably 85 V / min. elevated.

The thus coated substrate is further treated according to the parameters in Example 1, wherein the Blektrolyttemperatur 10 ⁰ C. The greyish white porcelain-like layer is suitable as a carrier for thick film circuits.

Claims (1)

- 6 - 2 2 3 8 5 8 invention claim 1. A process for the preparation of coated substrates for thick film circuits, characterized in that the substrate in an aqueous alkali-free electrolyte, preferably the composition 0.3 - 0.6 m NH ₁ P; 0.4 - 0.8 ra (NEL) ₂ CO-; 0.3 - 0.6 m (MH.KP (K with and without additions of amines by anodic oxidation under spark discharge is produced and an alkali-free insulating AIpOo - layer is formed ,, Method according to item 1, characterized in that the insulating AloO 2 layers are produced on substrates of aluminum or alloys or aluminum-iron composites. « 3, method according to item 1, characterized in that consisting of iron or alloys alumina. Hydroxide compounds, the insulating AIpO ^ layers are produced. 4 · Method according to items 1 to 3> characterized in that the insulating AlpO layers are applied to the substrate on one or both sides. • ~ 7