Patent Application
20070187233
1. Field of the Invention
The invention relates to electroplating and, more particularly, to an electroplating rack.
2. Description of the Related Art
Current electroplating processes require customized electroplating racks be built in order to hold workpieces (e.g., wafers or substrates for a printed circuit board) during the electroplating process. Such racks are customized based on the size of the workpieces, including the length, width and depth, and/or the shape of the workpieces. Additionally, with workpieces having different sizes or shapes a new thief plate must also be built for each workpiece as must new contact devices. Customizing such electroplating racks can be time-consuming and costly. Therefore, there is a need in the art for an electroplating rack that can be repeatedly used to hold workpieces with different sizes and/or shapes.
In view of the foregoing, embodiments of a universal electroplating rack and method of using the universal electroplating rack for repeatedly holding different workpieces with varying sizes and shapes during electroplating processes are disclosed.
Embodiments of the invention avoid building numerous customized plating racks to accommodate workpieces with different sizes and/or shapes by providing a universal electroplating rack that comprises a main body adapted to accommodate and electrically connect to one or more customized inserts. Each customized insert is adapted to accommodate and electrically connect to a single workpiece. Additionally, both the main body and the customized insert(s) comprise thief plates configured to improve plating uniformity across the plating surface area of the workpiece(s). Such a universal plating ensures a constant plating surface area regardless of workpiece size by varying the dimensions of the customized insert(s) so that universal processing parameters can be used for all workpieces.
More particularly, in one embodiment of the invention (i.e., a single workpiece embodiment), the universal plating rack comprises a main body and a single customized insert. The main body is adapted to hold and electrically connect to the customized insert. Specifically, the main body comprises a first aperture that extends through the main body from the first side to the second side of the rack, a metal surface (i.e., a first metal surface or thief plate) that surrounds the first aperture on the first side of the rack and a plurality of first conductors (i.e., contacts) that protrude into the first aperture at or near the second side of the rack.
The customized insert is adapted to hold and electrically connect to a single workpiece and to be inserted into the first aperture of the main body. The size and shape of the insert (i.e., the first size and the first shape) are customized to conform to the size and shape of the first aperture such when the insert is placed in the first aperture, the insert fits tightly, it contacts the first conductors and the top surface of the insert is on essentially the same plane as the top surface of the main body. The customized insert also comprises a second aperture that extends through the insert and a metal surface (i.e., a second metal surface or thief plate) that surrounds the second aperture on the first side of the rack. The insert further comprises a plurality of second conductors (i.e., contacts) that protrude into the second aperture at or near the second side of the rack. The size and shape of the second aperture (i.e., the second size and the second shape) are customized to conform to the size and shape of the single workpiece such that when the workpiece is placed in the second aperture, the workpiece fits tightly, it contacts the second conductors and the top surface of the workpiece is on essentially the same plane as the top surface of the insert. Thus, the combined top surfaces of the main body, the insert and the workpiece on the first side of the rack provide a constant and approximately level surface area to be electroplated so that universal electroplating processing parameters can be used.
In another embodiment of the invention (i.e., a multiple workpieces embodiment), the universal plating rack comprises a main body and multiple customized inserts.
The main body is adapted to hold and electrically connect to each of the customized inserts. Thus, in this embodiment the main body comprises not one but a plurality of first apertures that extend through the main body from the first side to the second side of the rack and a metal surface (i.e., a first metal surface or thief plate) that surrounds each of the first apertures on the first side of the rack. The main body further comprises a plurality of first conductors (i.e., contacts) that protrude into each of the first apertures at or near the second side of the rack.
The customized inserts are each adapted to hold and electrically connect to a corresponding workpiece and to be inserted into one of the first apertures of the main body. The outer dimensions of the inserts (i.e., the first sizes and first shapes) are customized to conform to the first apertures such that when the inserts are placed in the first apertures, the inserts fit tightly, the inserts contact the first conductors and the top surfaces of the inserts are on essentially the same plane as the top surface of the main body. Additionally, the first apertures can all be equal in size and shape such that all of the customized inserts will have the same outer dimensions. Each of these customized inserts also comprises a second aperture that extends through the insert and a metal surface (i.e., a second metal surface or thief plate) that surrounds the second aperture on the first side of the rack. The customized inserts can each further comprise a plurality of second conductors (i.e., contacts) that protrude into the second aperture at or near the second side of the rack. The size and shape of the second aperture (i.e., the second size and the second shape) for each of the inserts are customized to conform to specific corresponding workpieces such that when the corresponding workpieces are placed in the second apertures, the workpieces fit tightly, they contact the second conductors and the top surfaces of the workpieces are on essentially the same plane as the top surfaces of the inserts. Thus, the combined top surfaces of the main body, the inserts and the workpieces on the first side of the rack provide a constant and approximately level surface area to be electroplated so that universal electroplating processing parameters can be used.
An embodiment of the method of electroplating a single workpiece using a universal electroplating rack comprises first providing a main body for the universal electroplating rack. The main body comprises a first aperture, a plurality of first conductors that protrude into the first aperture and a metal surface (i.e., a first metal surface or first thief plate) surrounding the first aperture on the first side of the rack. Then, an insert is customized, as needed, for each specific workpiece that is to be electroplated using the universal electroplating rack. Specifically, an insert is formed with a size and shape that conforms to a size and a shape of the first aperture so that the insert can fit within the first aperture and can contact the first conductors. The insert is also formed with a second aperture that has a customized size and shape (i.e., a second size and a second shape), a plurality of second conductors that protrude into the second aperture (e.g., at or near the second side of the rack) and a metal surface (i.e., a second metal surface or thief plate) surrounding the second aperture. Specifically, this thief plate of the insert surrounds the second aperture on the first side of the rack when the insert is positioned within the first aperture. The size and shape of the second aperture are customized to conform to the size and shape of the specific workpiece to be electroplated so that the workpiece can fit within the second aperture and contact the second conductors. Additionally, the insert is customized so that when the specific workpiece is inserted into second aperture of the insert and the insert is inserted into the first aperture of the main body, the combined surfaces of the main body, the insert and the workpiece on the first side of the rack provide a constant and approximately level surface area to be electroplated. Due to this constant surface area, workpieces with different sizes and shapes that are electroplated using the same main body with a customized insert can be electroplated by applying universal plating parameters (i.e., by applying the same plating parameters).
An embodiment of the method of simultaneously electroplating multiple workpieces using a universal electroplating rack, as described above, comprises first providing a main body for the universal electroplating rack. The main body can comprise multiple first apertures. These multiple first apertures can each have the same size and shape. The main body can also comprise a plurality of first conductors that protrude into each of the first apertures and a metal surface (i.e., a first metal surface or first thief plate) on a first side of the rack surrounding the first apertures. Then, inserts are customized, as needed, for each of the workpieces that are to be simultaneously electroplated using the universal electroplating rack. Specifically, each insert is formed with a size and shape (i.e., first size and a first shape) that conforms to the size and shape of a first aperture so that each insert can fit within a first aperture and can contact the first conductors. Note that, as mentioned above, the first apertures can each have the same size and shape such that the multiple inserts are each formed with the same size and shape (i.e., the same first size and same first shape) and can fit within any of the first apertures. Each insert is also formed with a second aperture that has a customized size and shape (i.e., a second size and a second shape), a plurality of second conductors that protrude into the second aperture (e.g., at or near the second side of the rack), and a metal surface (i.e., a second metal surface or thief plate) that surrounds the second aperture. Specifically, the thief plate of each insert surrounds the second aperture on the first side of the rack when the insert is positioned within a first aperture. For each of the customized inserts, the size and shape of the second aperture are customized to conform to the size and shape of a corresponding specific workpiece so that the corresponding workpiece can fit within the second aperture and contact the second conductors. Additionally, each insert is customized so that when a each corresponding workpiece is inserted into the second aperture of its insert and the inserts are inserted into the first apertures of the main body, the combined surfaces of the main body, the inserts and the workpieces on the first side of the rack provide a constant and approximately level surface area to be electroplated. Due to this constant surface area, these workpieces with different sizes and shapes that are simultaneously electroplated using the same main body with a customized inserts can be electroplated by applying universal plating parameters (i.e., by applying the same plating parameters).
These, and other, aspects and objects of the present invention will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following description, while indicating embodiments of the present invention and numerous specific details thereof, is given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.
The invention will be better understood from the following detailed description with reference to the drawings, in which:
The present invention and the various features and advantageous details thereof are explained more fully with reference to the nonlimiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. It should be noted that the features illustrated in the drawings are not necessarily drawn to scale. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the present invention. The examples used herein are intended merely to facilitate an understanding of ways in which the invention may be practiced and to further enable those of skill in the art to practice the invention. Accordingly, the examples should not be construed as limiting the scope of the invention.
As mentioned above, current electroplating process flows require the building of a plating rack for each product based on product size. With the different-sized products, there is also a need to build a new thief plate and different-sized contact devices. Thus, different electroplating process parameters are required for each design. Consequently, current electroplating process flow necessitates added cost, as new products are introduced. Therefore, disclosed is a universal electroplating rack and method of using the rack. Specifically, a single rated plating rack is used and inserts are customized for each product size electroplated. The thief plate is incorporated into the insert as are contact devices, making the rack and process plating parameters universal. Additionally, a variety of universal inserts can be formed for to accommodate same-sized products.
More particularly, embodiments of a universal electroplating rack and method of using the universal electroplating rack for repeatedly holding different workpieces with varying sizes and shapes during electroplating processes are disclosed. These embodiments of the invention avoid building numerous customized plating racks to accommodate workpieces with different sizes and/or shapes by providing a universal electroplating rack that comprises a main body adapted to accommodate and electrically connect to one or more customized inserts. Each customized insert is adapted to accommodate and electrically connect to a single workpiece. Additionally, both the main body and the customized insert(s) comprise thief plates configured to improve plating uniformity across the plating surface area of the workpiece(s). Such a universal plating rack ensures a constant plating surface area regardless of workpiece size by varying the dimensions of the customized insert(s) so that universal processing parameters can be used for all workpieces.
The main body 105 is adapted to hold a customized insert 110 and to electrically connect to that customized insert 110. Specifically, the main body 105 comprises a first aperture 120 that extends through the main body 105 from the first side 101 to the second side 102 of the rack 100 and a metal surface 106 (i.e., a first metal surface or thief plate, such as a stainless steel frame) that surrounds the first aperture 120 particularly on the first side 101 of the rack 100. The main body 105 further comprises a plurality of first conductors 107 that protrude into the first aperture 120 at or near the second side 102 of the rack 100. These first conductors 107 can comprise metal contact devices that electrically connect the customized insert 110 to the main body 105 and can be formed either integral with or attached to the main body 105.
The customized insert 110 is adapted to be inserted into the first aperture 120 of the main body 105 such that the top surface of the insert 110 is essentially on the same plane as the top surface of the main body 105, to hold a single workpiece 140 such that the top surface of the workpiece 140 is essentially on the same plane as the top surface of the insert 110, and to electrically connect to the single workpiece 140.
Each new insert 110 is customized for each new product with a different size or shape, while the main body 105 of the rack 100 remains unchanged with repeated uses. Therefore, for each new customized insert 110 for a particular universal rack 100, the outer dimensions of the insert 110 (i.e., the first size, including length 411, width 412 and depth 413 (see
However, other dimensions of the insert 110 can vary for each product (i.e., a workpiece, such as a substrate or wafer) in order to hold the workpiece 140, electrically connect the workpiece 140 to the insert 110 and to ensure a constant and approximately level surface area for electroplating regardless of the size/shape of the workpiece 140 so that universal electroplating processing parameters may be used. Specifically, the size and shape of the second aperture 130 (i.e., the second size and the second shape) are customized to conform to the size and shape of the workpiece 140 such that when the workpiece is place in the second aperture 130, the workpiece 140 fits tightly, it contacts the second conductors 112 at or near the second side 102 of the rack 100, and the top surface of the workpiece 140 is essentially on the same plane as the top surface of the insert 110 on the first side 101 of the rack 100. Thus, referring to
The main body 505 is adapted to hold the customized inserts 510 and to electrically connect to those customized inserts 510. Specifically, the main body 505 comprises multiple first apertures 520 that extend through the main body 505 from the first side 501 to the second side 502 of the rack 500 and a metal surface 506 (i.e., a first metal surface or thief plate, such as a stainless steel frame) that surrounds the first apertures 520 particularly on the first side 501 of the rack 500. The main body 505 further comprises a plurality of first conductors 507 that protrude into the first apertures 520 at or near the second side 502 of the rack 500. These first conductors 507 can comprise metal contact devices that electrically connect the customized inserts 410 to the main body 505 and can be formed either integral with or attached to the main body 505.
Each of the customized inserts 510 is adapted to be inserted into a first aperture 520 of the main body 505 such that the top surface of the insert 510 is essentially on the same plane as the top surface of the main body 505, to hold a specific workpiece (e.g., 540a, 540b, etc.) such that the top surface of that specific workpiece is essentially on the same plane as the top surface of the insert 510, and to electrically connect to the that workpiece. As with the previously described embodiment,
Each insert 510 is customized for each new product having a different size or shape, while the main body 505 of the rack 500 remains unchanged with repeated uses. If the sizes and shapes of the first apertures 520 are all equal, all of the customized inserts 510 will have the same first size and the same first shape (i.e., the same outer dimensions). Specifically, if the first apertures 520 are symmetric, for each customized insert 510 for a particular universal rack 500, the outer dimensions of the insert 510 (i.e., the first size, including length 411, width 412 and depth 413 (see
However, other dimensions of the inserts (e.g., inserts 510a, 510b, etc.) can vary for each product (e.g., substrate or wafer) to be electroplated (i.e., each workpiece 540a, 540b, etc.) in order to hold the multiple workpieces 540, electrically connect the workpieces 540 to the inserts 510 and to ensure a constant and approximately level surface area for electroplating regardless of the varying sizes and/or shapes of the workpieces 540 so that universal electroplating processing parameters may be used. Specifically, the size and shape of the second aperture 530 of each insert (e.g., 510a, 510b, etc.) are customized to conform to the size and shape of specific workpieces (e.g., 540a, 540b, etc.) such that when the workpieces are place in the second apertures 530, they fit tightly, they contact the second conductors 512 at or near the second side 502 of the rack 500, and the top surfaces of the workpieces 540 are essentially on the same plane as the top surface of the inserts 510 on the first side 101 of the rack 100. Thus, referring to
Referring to
Then, an insert 110 is customized (712), as needed, for each specific workpiece 140 that is to be electroplated using the universal electroplating rack 100. Specifically, an insert 110 is formed with a size and shape (i.e., first size and a first shape) that conforms to a size and a shape of the first aperture 120 so that the insert 110 can fit within the first aperture and can contact the first conductors 107 (714). The insert 110 is also formed with a second aperture 130 (716) that has a customized size and shape (i.e., a second size and a second shape), a plurality of second conductors 112 that protrude into the second aperture 130 (e.g., at or near the second side 102 of the rack 100) (720) and a metal surface 111 (i.e., a second metal surface or thief plate) surrounding the second aperture 120 (721). Specifically, this thief plate 106 of the insert 110 surrounds the second aperture 120 on the first side 101 of the rack 100 when the insert 110 is positioned within the first aperture 120. The size and shape of the second aperture 130 are customized to conform to the size and shape of the specific workpiece 140 to be electroplated so that the workpiece 140 can fit within the second aperture 130 and contact the second conductors 112 (718).
Additionally, the insert 110 is customized so that when the specific workpiece 140 is inserted into second aperture 130 of the insert 110 and the insert 110 is inserted into the first aperture 130 of the main body 105 (at process 724), the combined surfaces of the main body 105, the insert 110 and the workpiece 140 on the first side 101 of the rack 100 provide a constant and approximately level surface area to be electroplated (722). The electroplating process can then proceed as follows. The universal plating rack 100 is placed in a plating tank containing a plating solution having conventional components (e.g., copper, silver, etc.) for the type of metal and features to be electroplated. Also placed in the plating tank is an anode. A power supply is connected between the anode and the universal rack, which acts as a cathode. As current flows between the anode and cathode, metallic features are plated onto the top surface of the workpiece 140 and the surrounding thief plates 106, 111 of the insert 110 and the main body 105. Due to the constant surface area formed at process 722, workpieces 140 with different sizes and shapes that are electroplated using the same main body 105 with different customized inserts can be electroplated by applying universal plating parameters (i.e., by applying the same plating parameters) (726). Specifically, regardless of the size and/or shape of the product being plated, the current will not need to be changed to maintain the same plating rate (Amps/cm2) because the Current/Surface Area=Plating Rate. Higher currents (i.e. plating rates), are more likely to disrupt the electric field, causing turbulence and erratic plating.
Referring to
Then, inserts 510 are customized, as needed, for each of the workpieces 540 that are to be simultaneously electroplated using the universal electroplating rack 500 (812). Specifically, each insert 510 is formed with a size and shape (i.e., first size and a first shape) that conforms to the size and shape of a first aperture 520 so that each insert 510 can fit within a first aperture 520 and can contact the first conductors 507 (814). Note that if the first apertures 520 each have the same size and shape, then the multiple inserts 510 are each formed with the same size and shape (i.e., the same first size and same first shape) and can fit within any of the first apertures (815). Each insert 510 is also formed with a second aperture 530 that has a customized size and shape (i.e., a second size and a second shape) (816), a plurality of second conductors 512 that protrude into the second aperture 530 (e.g., at or near the second side 502 of the rack 500) (820), and a metal surface 511 (i.e., a second metal surface or thief plate) that surrounds the second aperture (821). Specifically, the thief plate 511 of each insert surrounds the second aperture 530 on the first side 501 of the rack 500 when the insert 510 is positioned within a first aperture 520. For each of the customized inserts 510, the size and shape of the second aperture 530 are customized to conform to the size and shape of a corresponding specific workpiece (e.g., 540a, 540b, etc.) so that the corresponding workpiece can fit within the second aperture (e.g., 530a, 530b, etc.) and contact the second conductors 512 (818).
Additionally, each insert 510 is customized so that when each corresponding workpiece (9e.g., 540a, 540b, etc.) is inserted into a second aperture (e.g., 530a, 530b, etc.) of an insert 510 and the inserts 510 are inserted into the first apertures 520 of the main body 505 (at process 824), the combined surfaces of the main body 505, the inserts 510 and the workpieces 540 on the first side 501 of the rack 500 provide a constant and approximately level surface area to be electroplated (822). The electroplating process can then proceed as follows. The universal plating rack 500 is placed in a plating tank containing a plating solution having conventional components (e.g., copper, silver, etc.) for the type of metal and features to be electroplated. Also placed in the plating tank is an anode. A power supply is connected between the anode and the universal rack, which acts as a cathode. As current flows between the anode and cathode, metallic features are plated onto the top surfaces of the workpieces 540 and the surrounding thief plates 506, 511 of the inserts 510 and the main body 505. Due to the constant surface area formed at process 822, these workpieces 540 with different sizes and shapes that are simultaneously electroplated using the same main body 505 with customized inserts 510 can be electroplated by applying universal plating parameters (i.e., by applying the same plating parameters) (826). Specifically, regardless of the size and/or shape of the product being plated, the current will not need to be changed to maintain the same plating rate (Amps/cm2) because the Current/Surface Area=Plating Rate. Higher currents (i.e. plating rates), are more likely to disrupt the electric field, causing turbulence and erratic plating.
Therefore, the embodiments of the invention disclosed above avoid building numerous customized plating racks to accommodate workpieces with different sizes and/or shapes by providing a universal electroplating rack. The universal plating rack comprises a main body adapted to accommodate and electrically connect to one or more customized inserts. Each customized insert is adapted to accommodate and electrically connect to a single workpiece. Additionally, both the main body and the customized insert(s) comprise thief plates configured to improve plating uniformity across the plating surface area of the workpiece(s). Such a universal plating rack ensures a constant plating surface area regardless of workpiece size by varying the dimensions of the customized insert(s) so that universal processing parameters can be used for all workpieces. Consequently, for each new product developed, the universal electroplating racks of the invention will effectively reduce introduction costs, will avoid the need to qualify new electroplating process parameters (e.g., cycle time), and will effectively reduce lead time required. Additionally, the universal plating racks of the invention will allow experiments to be conducted more easily for possible future products. While the invention has been described in terms of embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the appended claims.
