The present invention generally relates to high speed packages, and more specifically relates to the removal of plating tails on substrates for high speed packages.
In making a high speed package, a chemical etching and electro plating processes are used to form traces on a substrate. The traces are formed to interconnect the silicon chip to pads on the package. The tips and pads of the package requires electro plating of nickel and gold or similar precious metals for interconnection by gold wire bonding to the silicon chip. The electroplating process requires the connection of all the metal traces to a common bussbar, generally on the perimeter of the package. These additional metal traces are commonly called plating tails. Plating tails are generally undesirable because they have an antenna effect, affecting the electrical performance of the package. To remove the plating tails, a chemical etching process is performed. Hence, one or more additional processing steps are performed to eliminate the plating tails which are connected to traces associated with high speed I/O's.
Alternatively, an electroless plating process is used to form the traces on the substrate. As such, no plating tails are formed during the process which must thereafter be removed in a subsequent chemical etching process. However, there is additional cost and complexity involved with electroless plating compared to electroplating.
An object of an embodiment of the present invention is to provide a simple and inexpensive method of removing plating tails (or portions of plating tails) after an electroplating process has been performed to form traces on a substrate.
Another object of an embodiment of the present invention is to provide a method of removing plating tails (or portions of plating tails) without having to perform a chemical etching process.
Still another object of an embodiment of the present invention is to provide that a substrate without plating tails can be formed, without having to form the traces using an electroless plating process and without having to perform a chemical etching process to remove the plating tails after the traces have been formed.
Briefly, and in accordance with at least one of the foregoing objects, an embodiment of the present invention provides a method wherein a substrate with plating tails is formed or otherwise provided, such as by performing a conventional electroplating process. Subsequently, a laser is used to remove some or all of the plating tails, or a portion of some or all of the plating tails.
If portions or remnants of the plating tails are to remain, the plating tails can be connected to ground. By connecting the remnants of the plating tails to ground, an electrical performance enhancement can be realized. Specifically, additional shielding in the package can be provided. Furthermore, the plating tails can be specifically designed to enhance the amount of shielding they provide.
The organization and manner of the structure and operation of the invention, together with further objects and advantages thereof, may best be understood by reference to the following description, taken in connection with the accompanying drawings, wherein:
While the invention may be susceptible to embodiment in different forms, there are shown in the drawings, and herein will be described in detail, specific embodiments of the invention. The present disclosure is to be considered an example of the principles of the invention, and is not intended to limit the invention to that which is illustrated and described herein.
Subsequently, a laser is used to remove the plating tails 14. Specifically, a laser is used to cut away either a portion of some or all of the plating tails 14, or to remove the entire plating tail 14 (either all of the platings or just some of the plating tails).
By removing the entire plating tail, possible undesirable consequences associated with high speed switching can be avoided. On the other hand, if remnants 20 of the plating tails 14 are to remain as shown in
Not all of the plating tails need to be removed (or partially removed). For example, only selected plating tails connected to high speed signals need to be removed, thus improving the efficiency and cost of the process. The substrate can be customized for each specific application.
The present invention provides a simple and inexpensive method of removing plating tails (or portions of plating tails), without having to perform a chemical etching process. Assuming the entire plating tail is removed, the method provides that a substrate without plating tails can be provided (see
While embodiments of the present invention are shown and described, it is envisioned that those skilled in the art may devise various modifications of the present invention without departing from the spirit and scope of the appended claims.