Combined electrochemical and laser micromaching process for creating ultri-thin surfaces

Abstract

Ultra-thin sections in an electrically conducting material are formed by electrochemically removing material to a thickness of approximately 5 to 150 micrometers and removing further material by laser micromachining to a material thickness of 1 to 30 micrometers. The electrochemical process quickly removes substantial material but is not as precise and accurate as laser machining to create the ultra-thin sections or translucent sections. Removing material by an electrochemical process may be controlled down to a thickness of approx. 10-12 micrometres so that enough margin of a material thickness is left at the bottom of this first cavity. The laser micromachining process removes remaining material down to a predetermined level, e.g. 1-5 micrometres, relatively rapidly, so that a relatively quick process for the manufacture of ultra-thin sections in an electrically conducting material is achieved. A metal structure manufactured by the novel and inventive process is disclosed.

1 . Process for the manufacture of ultra thin sections in an electrically conducting material, comprising:
 firstly removing material in an electrochemical process to a material thickness of approximately 5-150 micrometers;   secondly removing further material by a laser micromachining process to a material thickness of 1 to 30 micrometers.   
   
   
       2 . Process according to  claim 1  wherein the electrochemical process removes material down to a material thickness of 10 to 20 micrometers, and further that the laser micromachining process removes further material down to a material thickness of 1 to 5 micrometers. 
   
   
       3 . Process according to  claim 1  wherein the electrochemical process is a controlled anodic dissolution process, where the material is the anode and a tool having a distal end acting as cathode so that a reaction cell is created between the anode and cathode, and that a salt containing electrolyte is led to the reaction cell through a conduit in the tool. 
   
   
       4 . Process according to  claim 3  wherein the electrolyte is forced through the conduit to the reaction cell, and where the distance between the anode and cathode during the dissolving process is maintained substantially constant. 
   
   
       5 . Process according to  claim 3  wherein the tool has a cross-section substantially corresponding to the area of the resulting ultra thin section, and where said tool is substantially cylindrical, and the cylindrical section on the outside is provided with a non-conductive coating. 
   
   
       6 . Process according to  claim 1  wherein the laser micromachining process is performed by a high power femtosecond laser device emitting laser light pulses, where the pulse length is between 150 femtoseconds and 15 picoseconds, preferably between 150 femtoseconds and 10 picoseconds and more preferably 1 picosecond. 
   
   
       7 . Process according to  claim 6  wherein the laser is controlled in a scanning mode and scans the desired area of the ultra thin section in a predetermined pattern. 
   
   
       8 . Process according to  claim 6  wherein the laser beam is passed through beam shaping optics in order to create a homogeneous laser beam shape or an Excimer type laser is used. 
   
   
       9 . Process according to  claim 1  wherein a light detector is arranged on the opposite side of the material from which the laser process is being performed, where said light detector is preprogrammed to switch off the laser device when a certain predefined luminance is detected. 
   
   
       10 . Process according to  claim 1  wherein a light beam, for example a laser beam, is directed into the ultra thin section, and where a light detector is arranged on the opposite side of the material from which the laser process is being performed, where said light detector is pre-programmed to switch off the laser device when a certain predetermined luminance is detected. 
   
   
       11 . Process according to  claim 1  wherein the electrochemical process creates a first cavity, inside which first cavity the laser micromachining process creates a number of second cavities, through which second cavities light may shine through, where the number of second cavities is in the range of 20 to 200 pr first cavity, more preferred 50 to 150 pr first cavity and most preferred 90 to 110 pr first cavity. 
   
   
       12 . Metal structure having a front side and a back side, wherein said front and back sides define a material thickness between them, and where in said back side of the structure ultra thin sections manufactured according to  claim 1  are present, such that when a source of light is present behind one or more of the ultra thin sections in said metal structure, the ultra thin sections are emitting light, and when no light is present, the front side appears undisturbed.