Adhesive bonding and miscellaneous chemical manufacture – Differential fluid etching apparatus – With microwave gas energizing means
Patent
1998-01-28
2000-05-09
Osele, Mark A.
Adhesive bonding and miscellaneous chemical manufacture
Differential fluid etching apparatus
With microwave gas energizing means
156584, 118411, 134 26, 134 34, 134 64R, B32B 3500
Patent
active
060599197
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method for uniform chemical detachment of layers of resists, particularly of photoresists, in the form of easily-filterable particles, from the surfaces of plate-shaped material for electrolysis, for example printed circuit boards and printed circuit films, by means of a solvent, and for removing the detached resist from the solvent.
In printed circuit technology resists serve to cover surfaces not to be treated. For this purpose for example photo-resists and screen-print paints are used.
In the manufacture of printed circuit boards, the following process steps among others are carried out: if necessary through hole plated, with a solid or liquid photo-resist, also called film. This as a rule involves a light-sensitive swellable polymer. board process used, reproduces the conductor image positively or negatively. points. The other points remain as hard and securely adhering layers on the surface of the material for treatment. conductor pattern, i.e. with copper and then with tin or a tin/lead alloy as an etching resist. surfaces with an aqueous solvent, and is thus totally removed.
Film stripping is preferably carried out chemically in horizontal continuous systems. Here the aqueous solution of the solvent is applied by spraying or squirting to the surfaces to be treated. A widely used agent for film stripping is caustic soda. There are also known for this purpose aqueous solutions which for example contain amino compounds or ionic nitrogen compounds as well as alkaline or earth-alkaline hydroxides and mixtures of these compounds. During stripping, the film is intended as far as possible only to be detached and not dissolved, as a film dissolved in the solution can no longer be filtered out. This would give rise to corresponding disposal problems and in particular to a short service life of the bath. Therefore the film for this purpose is firstly partially dissolved in a first process step and thereafter detached. The method step of pantial dissolution which is also named the swelling step, and the detachment procedure are carried out in a common bath with a plurality of spray and/or squirt registers.
The following disadvantages occur in known methods: partially dissolves the film in an acceptable time, yet does not too intensely dissolve it during the subsequent detachment. This contradiction may only be resolved by a compromise. In an excessively long treatment time, a portion of the film becomes dissolved, so that it can no longer be removed by filters. If the treatment time is too short, the film is not entirely removed from the surfaces. of liquid cannot be conveyed on to the surfaces by spraying or squirting. There is no intimate contact of the solution with the film to be swelled. intensive spraying at high pressure. In this process however the film is broken into small particles. These particles, due to their large surface, dissolve more quickly. Mechanically-acting filters for removing the detached film from the solution are ineffective for the dissolved proportion of the film. The service life of such a film stripping bath is therefore unsatisfactory. anti-foaming agents must be added to the aqueous solution. A number of disadvantages arise from the use of these agents: the walls of the working container and on the transport rollers. the surface of the material for treatment. Subsequent processes are influenced by this. Occasionally faults occur during stripping of the tin/lead alloy. The adhesive emulsion is in particular pressed in a securely adhesive manner between extremely fine conductor tracks. In order to remove the impurities, attempts are made to apply a spray at a higher pressure to the surfaces. This is moderately successful, but only with printed circuit boards. Printed circuit films are difficult to transport during a spray treatment. At a high spray pressure, for example at 10 bar, printed circuit films can no longer be transported, or so many guide members are necessary that the film surfaces are not sufficiently accessible. plasticisers out of plastic ma
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Baron David T.
Schneider Reinhard
Atotech Deutschland GmbH
Osele Mark A.
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