Gas Electron Multiplier Hole Registration via Selective Electrochemical Etching
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Solution Overview
Problem
Existing methods for manufacturing gas electron multipliers (GEMs) face challenges in ensuring precise co-registration of patterns on larger sizes, leading to shifted hole centers and functional issues due to instability and deformation of masks, particularly with temperature and humidity changes.
Innovation Solution
A method involving electrochemical etching, where only one metal layer is patterned, and holes are extended through the insulating sheet and the second metal layer using electrochemical or chemical etching processes, ensuring selective etching of the second metal layer without damaging the first metal layer, and maintaining precise control over etching to prevent ring formation on the first metal layer side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If two identical masks are used for patterning both metal layers, then the manufacturing process can be simplified, but the co-registration precision deteriorates due to mask deformation with temperature and humidity changes
Solution Approach 1:
The patent extracts the patterning step from both metal layers, applying it only to the first metal layer. The second metal layer is etched using a different approach (chemical or electrochemical etching) that does not require photolithographic patterning. This eliminates the need for two masks and their associated co-registration problems while maintaining manufacturing simplicity.
Solution Approach 2:
The patent introduces an intermediary etching process that acts as a mediator between the patterned first metal layer and the final throughhole formation. This intermediary step (chemical or electrochemical etching of the second metal layer) allows precise hole formation without requiring direct photolithographic patterning of the second layer, thus avoiding mask deformation issues.
2Reliability
If electrochemical etching is used for the second metal layer, then selective etching can be achieved without damaging the first metal layer, but the process complexity increases
Solution Approach 1:
The patent applies local quality by using electrochemical etching specifically for the second metal layer while leaving the first metal layer intact. The electrochemical process is localized to the second layer through controlled electrode positioning and electrical potential application, enabling selective removal of the second metal layer without affecting the first layer.
Solution Approach 2:
The patent changes the etching parameters by switching from photolithographic patterning to electrochemical etching for the second metal layer. This parameter change involves controlling electrical potential, current density, and electrolyte composition to achieve selective etching of the second metal layer while preserving the first metal layer's integrity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method allows for the production of high-quality GEMs even at larger sizes by preventing damage to the first metal layer during the second metal layer etching step, maintaining the structural integrity and performance of the device.
Implementation Method 1
a second metal layer hole forming step in which the holes formed in the first metal layer and the insulating sheet are extended through the second metal layer, said second metal layer hole forming step comprising an electrochemical etching process in which a voltage is applied between the second metal layer and an electrode immersed in the etchant
Data Source
Figure 1
Figure 2~3
Figure 4A~4E
AI summary
A method of manufacturing a gas electron multiplier is shown. The method comprises a step of preparing a blank sheet (28) comprised of an insulating sheet (12) with first and second metal layers (14, 16) on its surface, a first metal layer hole forming step in which the first metal layer is patterned by means of photolithography, such as to form holes (18) through the first metal layer, an insulating sheet hole forming step, in which the holes (18) formed in the first metal layer (14) are extended through the insulating layer (12) by etching from the first surface side only, and a second metal layer hole forming step, in which the holes (18) are extended through the second metal layer (16). In one embodiment, the second metal layer hole forming step is performed by electrochemical etching, such that the first metal layer (14) remains unaffected during etching of the second metal layer (16). In another embodiment, in the second metal layer hole forming step, the first and second metal layers (14, 16) are etched from the outside, thereby reducing the initial thicknesses of the first and second metal layers (14, 16) and the second metal layer (16) is simultaneously etched through the holes (18) in the first metal layer (14) and the insulating sheet (12), said etching being maintained until the holes (18) extend through the second metal layer, wherein said initial average thickness of the first and second metal layers (14, 16) is between 6.5 μm and 25 μm, preferably between 7.5 μm and 12 μm.