Membrane with perforations, method for producing such a membrane and separating device comprising one or more of such membranes
First Claim
1. Membrane for separating media containing several constituents which is a foil having a plurality of symmetrically shaped perforations, said foil consisting entirely of electroformed metal of uniform thickness, the perforations being arranged in a predetermined regular pattern forming a plurality of regions each having all the same desired perforation density, the perforation density being at least 150,000 perforations/cm2, and in which the remaining regions of the foil includes an unperforated area between at least two perforation regions.
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Accused Products
Abstract
Described, is a membrane and its method of manufacturing which membrane is an electroformed metal foil having areas of high perforation density (higher than 150000/cm2) and unperforated areas and in particular also unperforated areas having greater thickness than the other areas.
The membrane is produced in a process comprising a two step photolithographic procedure in which canals formed in the first photolithographic step are used to ensure good vacuum contact during the second photolitographic step in which the high density pattern is formed in the photolacquer used.
The invention also relates to a separation device incorporating one or more membranes according to the invention.
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Citations
20 Claims
- 1. Membrane for separating media containing several constituents which is a foil having a plurality of symmetrically shaped perforations, said foil consisting entirely of electroformed metal of uniform thickness, the perforations being arranged in a predetermined regular pattern forming a plurality of regions each having all the same desired perforation density, the perforation density being at least 150,000 perforations/cm2, and in which the remaining regions of the foil includes an unperforated area between at least two perforation regions.
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7. Method for producing a membrane having a perforation density in a plurality of predetermined areas of at least 150000/cm2,
wherein, in a first step, a photoresist pattern, the resist-free regions of which correspond to the unperforated regions to be present in the finished membrane, is formed on an electrically conducting substrate by coating with photo-resist, exposure using a suitable film and development; -
wherein a subsequent exposure and development is then carried out using a mask suitable for the purpose and, making use of vacuum contact and a suitable light source, whereby a pattern is formed in the photoresist regions left behind after the first step, the uncoated areas in said pattern corresponding to the metal between the perforations in the regions of the finished membrane where the perforation density has the desired value; wherein the substrate thus provided with a composite photoresist pattern is subjected to an electroplating operation for depositing metal on all the uncoated regions; and
wherein the metal deposit thus formed is removed. - View Dependent Claims (8, 9, 10, 11, 20)
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15. Device for separation of a medium containing several constituents comprising at least a housing, medium feeding and withdrawal means and means for mounting at least one membrane and a mounted membrane according to 1 wherein the unperforated regions of said membrane carry electroformed metal thereby to cause such unperforated regions to have a greater thickness than the regions in which the perforation density has the desired value and in which the foil has a thickness which is insufficient to make the membrane self-supporting and the thickness of the electroformed metal on the unperforated regions is sufficient to make the resulting membrane self-supporting.
Specification