US20120279862A1

US20120279862A1 - Continuous micro anode guided electroplating device and method thereof

Info

Publication number: US20120279862A1
Application number: US13/554,662
Authority: US
Inventors: Jing-Chie Lin; Ting-Kang Chang; Jen-Hung Yang; Yean-Ren Hwang; Ting-Chao Chen
Original assignee: National Central University
Current assignee: National Central University
Priority date: 2009-05-27
Filing date: 2012-07-20
Publication date: 2012-11-08
Also published as: US20100300886A1; TW201042099A; TWI417428B

Abstract

A continuous micro anode guided electroplating device and a method thereof are revealed. By real-time image monitoring and capillary action of the micro/nanoscale tube, a three-dimensional microstructure is deposited on a workpiece at the cathode. The deposit is growing smoothly under the real-time image monitoring. Moreover, the workpiece is not immersed in an electrolyte so that contaminations of the workpiece caused by electrolyte are reduced.

Description

The current application is a divisional application of, and claims a priority to U.S. Ser. No. 12/570,080 filed on Sep. 30, 2009, which claims a foreign priority to application of Taiwan 098117693 filed on May 27, 2009.

BACKGROUND OF THE INVENTION

1. Field of Invention
The present invention relates to a micro anode guided electroplating device and a method thereof, especially to a continuous micro anode guided electroplating device and a method thereof.
2. Description of Related Art
Along with fast development of and great advancement in modern technology, the electronic products are getting compact and light weighted. Similarly, the establishment of micromechanical devices provides more benefits. When the mechanical devices are getting smaller, its resonance frequency increases. Thus high bandwidth accelerometers and pressure gauges are produced. The microelements integrate drivers, limbs, sensors, processors and power supplies so as to move around the world under the microscope and applied to medical field.
Milling, welding and fastening of conventional mechanical devices haven't achieved the space resolution required by the microelements. Integrated circuits have been widely applied to mechanical devices, electromechanical devices and opto-electro-mechanical systems in millimeter size and micrometer size. But the uniform thickness structure with low aspect ratio is unable to achieve optimal performance. Although the aspect ratio can be increased by the lithographic technology such as LIGA (Lithography Electroforming Micro Molding), the lithographic technology is a two-dimensional manufacturing method. The three-dimensional structure is produced by laser cutting, Laser Assisted Chemical Vapor Deposition, and stereolithography. The most common way used is lithographic technology in which thin films are selectively removed by etching to leave the desired film pattern after deposition. By local heating or setting a small piece of electrode near the substrate for local reaction, local deposition rate is improved.
Moreover, mechanical devices can also be produced by local micro electroplating. In the local micro electroplating, a three-dimensional micro positioning member drives a micro anode so that the micro anode moves in a constant speed along a preset track. The potential is controlled to perform DC (direct current) electroplating. However, the deposition rate is not constant so that the micro anode moving in a constant speed will not lead to constant growing of the deposit. If the micro anode moves too fast, the deposit is gradually reduced in size and finally grows nothing with increasing the distance between the electrodes. On the contrary, if the micro anode moves too slowly, the deposits contact with the micro anode and a short circuit occurs.
The meaning of the constant speed has been lost.
Thus the constant movement of the micro anode is unable to ensure a stable deposit rate. Thus the deposit is grown in non-uniform size or the electroplating may be interrupted. Both have affected the quality of electroplated micro components significantly.

SUMMARY OF THE INVENTION

Therefore it is a primary object of the present invention to provide a micro anode guided electroplating device and a method thereof in which a workpiece is not soaked in an electrolyte (electroplating solution) so as to reduce the contaminations of the workpiece caused by the electrolyte.
It is another object of the present invention to provide a micro anode guided electroplating device and a method thereof in which real-time image monitoring and capillary action of micro/nanoscale capillary are combined. A three-dimensional microstructure is deposited on a workpiece at the cathode. The deposit is growing smoothly by the real-time image monitoring of the electroplating process.
It is a further object of the present invention to provide a micro anode guided electroplating device and a method thereof in which an electric field strength of the micro anode is controlled so that the electric field strength between the micro anode and the cathode remains stable for generating deposit with a smooth and uniform surface.
It is a further object of the present invention to provide a micro anode guided electroplating device and a method thereof in which a monitor is used to monitor the distance between the micro anode and the cathode and control a loading platform carrying the cathode so as to maintain the distance between the micro anode and the cathode at a fixed value and avoid defects in the deposit.
In order to achieve above object, a continuous micro anode guided electroplating device and a method thereof according to the present invention consists of a micro anode, a loading platform, a cathode, a power supply and a monitor. The micro anode is formed by a micro/nanoscale capillary filled with an electrolyte and a conductor disposed in the capillary. The loading platform is arranged under the micro anode while the cathode is a workpiece that is put on the loading platform to be electroplated. The power supply is connected to the conductor of the micro anode as well as the cathode so as to supply a bias to the micro anode and the cathode and generate a deposit on the surface of the cathode. The monitor is connected to the power supply as well as the loading platform. The power supply provides the monitor electricity and the monitor checks the distance between the micro anode and the cathode so as to control movement of the loading platform and adjust the distance between the micro anode and the cathode into a fixed value.
In a continuous micro anode guided electroplating device and a method thereof of the present invention, the micro anode is firstly set above the cathode and an electrolyte is added into the micro anode. Then apply a bias to the micro anode and the cathode so that a deposit is generated at the cathode. Next take an image between the micro anode and the cathode. Finally, check a distance between the micro anode and the cathode according to the image and the loading platform is controlled so as to maintain the distance between the micro anode and the cathode into a fixed value.

BRIEF DESCRIPTION OF THE DRAWINGS

The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings, wherein

FIG. 1 is a schematic drawing showing structure of an embodiment according to the present invention; and

FIG. 2 is a flow chart of an embodiment according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Refer to FIG. 1, a continuous micro anode guided electroplating device 1 includes a micro anode 1, a loading platform 12, a cathode 14, a power supply 16 and a monitor 18. The micro anode 10 consists of a micro/nanoscale capillary 101 and a conductor 103. The conductor 103 is made from platinum and is disposed inside the capillary 101 that is filled with an electrolyte (electroplating solution) 2. The loading platform 12 is set under the micro anode 10 and is having a driving device 121 therein. The driving device 121 drives the loading platform 12 to move. In this embodiment, the driving device 121 is a motor. The cathode 14 is a workpiece that is put on the loading platform 12 for electroplating. The power supply 16 is composed of an anode and a cathode. The anode of the power supply 16 is connected to the micro anode 10 and the cathode of the power supply 16 is connected to the cathode 14. The power supply 16 supplies a bias to the micro anode 10 and the cathode 14 so that a deposit is generated at the cathode 14. The monitor 18 consists of an image capture device 181 and a controller 183. In this embodiment, the image capture device 181 is a CCD (Charge-coupled Device). The image capture device 181 takes an image between the micro anode 10 and the cathode 14 and sends the image back to the controller 183. Then the controller 183 performs binary image processing so as to check and calculate the distance between the micro anode 10 and the cathode 14. The distance between the micro anode 10 and the cathode 14 must be maintained at a fixed value. Thus the controller 183 controls the movement of the loading platform 12 according to the distance between the micro anode 10 and the cathode 14 calculated by means of the image so as to adjust and maintain the distance between micro anode 10 and the cathode 14 at a fixed value. The controller 183 is a computer.
Refer to FIG. 2, a flow chart of an embodiment is revealed. As shown in figure, a continuous micro anode guided electroplating is performed by the device mentioned above. At first, take the step S10, disposed the micro anode 10 above the cathode 14 and the micro anode 10 is slowly close to the cathode 14. Then run the step S12, add an electrolyte 2 into a micro/nanoscale capillary 101 of the micro anode 10 and the electrolyte 2 forms a semicircular drop on an opening of the capillary 101. When the micro anode 10 is getting close to the cathode 14, the semicircular drop contacts with the surface of the cathode 14 in a semilunar form (a great C-shaped) due to surface tension.
Next refer to the step S14, apply a bias to the micro anode 10 and the cathode 14. Then take the step S16, metal ions in the electrolyte 2 of the micro anode 10 are deposited at the cathode 14 to grow into a deposit on the surface of the cathode 14. While the deposit is growing, run the step S18, take an image between the micro anode 10 and the cathode 14 by the image capture device 181 of the monitor 18 and the image is sent to the controller 183 of the monitor 18 by the image capture device 181. Later take the step S19, estimate a distance between the micro anode 10 and the cathode 14 by the controller 183 according to the image because the distance between the micro anode 10 and the cathode 14 must be maintained at a fixed value. The fixed distance ranges from 10 mm (micrometer) to 20 mm. Thus the controller 183 calculates the distance between the micro anode 10 and the cathode 14 according to the image and controls the movement of the loading platform 12.
At last, repeat the step S10 to the step S19 mentioned above until the deposit grows into a preset shape and structure. By the real-time image monitoring and capillary action of the micro/nanoscale tube, a three-dimensional microstructure is deposited on the workpiece at the cathode. The deposit is growing smoothly under the real-time image monitoring.
In summary, a micro anode guided electroplating device and a method thereof of the present invention reduce contaminations of the workpiece because the workpiece is not immersed in the electrolyte. The micro anode guided electroplating device and the method thereof combines real-time image monitoring with capillary action of the micro/nanoscale tube. A three-dimensional microstructure is deposited on the workpiece at the cathode. The deposit is growing smoothly under the real-time image monitoring. Moreover, an electric field strength of the micro anode of the present invention is controlled so that an electric field strength between the micro anode and the cathode remains stable. Thus the deposit is with a smooth and uniform surface. Furthermore, by a monitor, the distance between the micro anode and the cathode is monitored and the loading platform carrying the cathode is controlled so as to maintain the distance between the micro anode and the cathode at a fixed value and prevent defects in the deposit.
Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, and representative devices shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

Claims

1. A method of continuous micro anode guided electroplating comprising the steps of:

disposing a micro anode above a cathode,

adding an electrolyte into the micro anode,

applying a bias to the micro anode and the cathode,

generating a deposit at the cathode from the micro anode,

capturing an image between the micro anode and the cathode, and

checking a distance between the micro anode and the cathode according to the image and controlling movement of a loading platform so as to maintain the distance between the micro anode and the cathode at a fixed value.

2. The device as claimed in claim 1, wherein the fixed value of the distance ranges from 10 mm (micrometer) to 20 mm.

3. The device as claimed in claim 1, wherein the image is treated by binary processing.

4. The device as claimed in claim 1, wherein the micro anode includes a capillary and a conductor while the conductor is disposed inside the capillary.

5. The device as claimed in claim 4, wherein the conductor is made from platinum.