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US 2001/0019744 A1Published application
Process for plating metal coatings
AssigneeAtotech Deutschland GmbH
InventorsHeinrich Meyer, Ralf Schulz
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AssigneeAtotech Deutschland GmbH
InventorsHeinrich Meyer, Ralf Schulz
Estimating the term…
There are known for use in the electronics industry polyimide substrates with copper coatings, which are produced by decomposition of organometallic compounds by means of a glow discharge process and subsequent electroless metallization of the resulting metal film. From deposition of the first metal coating there results, without addition of oxygen, carbon-containing layers which have a low conductivity and low catalytic activity. If only alkaline metallizing baths are used, initially securely adhering metal coatings are in fact deposited on the polyimide surfaces, the secure adhesion of the metal coatings on the polyimide however is considerably impaired upon contact of the metal with aqueous-alkaline solutions. If operation is in an oxygen atmosphere, palladium layers result which must be subsequently reduced. Such layers provide no or very small adhesion, when they are exposed to chemical or electrochemical process solutions. By using mixtures of oxygen-containing compounds and inert gas during metal deposition in the glow discharge, low-oxygen and low-carbon layers are produced. Moreover, the reduction in secure adhesion upon contact of the metallized substrate with aqueous-alkaline solutions can be avoided by using acidic or neutral electroless metallizing baths to produce the second metal coating. This process for the first time achieves the manufacture of highly-condensed circuit bases from a basis of unmetallized polyimide films.
Process for depositing metal coatings adhering, resistantly to aqueous-alkaline solutions, on polyimide surfaces, particularly for producing micro-fine conductor track structures, with the following essential process steps:
Process according to one of the preceding claims, characterised in that oxygen (O2) is used as an oxygen-containing compound.
Process according to one of the preceding claims, characterised in that the ratio of the partial pressure of the oxygen-containing compounds to that of the inert gases in the gas mixture is set to a value between 2:1 and 1:8, preferably between 1:3 and 1:4.
Process according to one of the preceding claims, characterised in that the partial pressure of the gas mixture is set to a value of between 1 Pa and 50 Pa.
Process according to one of the preceding claims, characterised in that palladium compounds are used as volatile metal compounds.
Process according to one of the preceding claims, characterised in that the first metal coating is deposited at a thickness of from 0.01 μm to 0.1 μm.
Process according to one of the preceding claims, characterised in that the pH value of the metallising bath for electroless deposition is set between 2 and 8, preferably between 2 and 7.
Process according to one of the preceding claims, characterised in that, for electroless metallisation, a nickel, copper, cobalt, palladium or alloy bath of these metals is used.
Process according to one of the preceding claims, characterised in that a nickel/boron alloy layer or a nickel/phosphorus alloy layer with a phosphorus content of between 3 and 5% by weight of phosphorus, or a palladium layer is deposited in an electroless manner as the second metal coating.
Process for manufacturing an electrical circuit base, comprising an electrically non-conducting substrate with polyimide surfaces, conductor tracks with conductor track widths and spacings of substantially below 100 μm and with holes with diameters of substantially under 100 μm, capable of being produced by means of the following essential process steps:
Process for depositing metal coatings on polyimide surfaces, characterised by all the new features and combinations of disclosed features.
Process for producing an electrical circuit base, characterised by all the new features and combinations of disclosed features.
Dependencies are inferred from the claim text.