Electricity: conductors and insulators – Conduits – cables or conductors – Preformed panel circuit arrangement
Reexamination Certificate
2001-12-07
2003-01-28
Paladini, Albert W. (Department: 2827)
Electricity: conductors and insulators
Conduits, cables or conductors
Preformed panel circuit arrangement
C257S786000, C361S774000, C361S777000
Reexamination Certificate
active
06512180
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to printed-wiring board mounted onto electronic devices, such as personal computers (hereinafter referred to as “PCs”), and more particularly to a method for identifying the printed-wiring board. The printed-wiring board to which the present invention is applicable covers a broad range of printed-wiring boards, such as those to be mounted onto a PC, a cellular phone and other electronic devices.
Along with the recent technology development, electronic devices, such as PCs and cellular phones, have become increasingly smaller and adopted more diversified designs. Accordingly, a wide variety of shapes of circuit boards have also been used from motherboards to be mounted onto PCs and cellular phones to package circuits (sometimes referred to as a Chip Sized Packages (“CSPs”). These printed-wiring boards (referred to as a “board” hereinafter unless otherwise specified) include a conductive part, such as a wiring pattern, and the conductive part includes a plurality of fine pads which assist in an electric connection between terminals of a circuit element, such as a semiconductor chip, and the wiring pattern.
Some manufactures produce such printed-wiring boards by themselves, while others are supplied with these printed-wiring boards from one or more vendors. Generally, in requesting a third party to manufacture the above printed-wiring boards, a PC manufacturer, for example, provides its vendor with a schematic blueprint of the board as manufacturing data readable with a CAD/CAM, and requests the vendor to deliver the boards. In response, the vendor processes and modifies the manufacturing data such that the vendor may actually produce the board, and then submits the modified data to the manufacturer for permission, after putting down ID data (referred to as an “identifier” hereinafter), such as an alphanumeric character, onto an insulating part on the board.
The identifier is usually expressed, for example, through etched and cutout letters in a conductive layer closest to the board surface, a marking process using ink onto the board surface, and a stamp process. Any of these methods may visualize the identifier for microscopic test.
However, as the recent reduced board size and wiring high-density progress, it often becomes difficult to indicate the identifier on the board. For example, in a CSP as a typical example, the reduced board size and wiring high-density narrow a space for the identifier made of marked, stamped, and etched or cutout letters. On the other hand, even when there is a space enough for the identifier, some PC manufacturers often refuse the insertion of the identifier to keep board's external appearance. For example, a certain PC manufacturer uses some vendors, and prefers the same external appearances for all the boards delivered from these vendors; for this reason, the PC manufacturer does not like to allow these vendors to indicate their unique identifiers.
The PC manufacturer performs an acceptance test for boards delivered from the vendor, and returns to them those boards which have been determined as inferior products. The vendor then attempts to investigate the cause and state of any returned, inferior board, but could not if the board does not have any identifier that enables the vendor to find out board's manufacture date, shipping date, type, etc. Therefore, there has been a demand to provide a board with an identifier.
As an identification approach without greatly marring board's external appearance, Japanese Laid-Open Patent Application No. 6-296065 proposes putting an identifier onto board's disused board part located around and cut down from a product part that is used as a finished product. Nevertheless, the method according to this reference cannot neither identify the product part that has been separated from the disused board part, nor investigate the inferior products. Japanese Laid-Open Patent Application No. 6-112603, on the other hand, proposes identifying a board by forming a plurality holes in the insulating part instead of using alphanumerical characters, and by opening and closing each of them. However, it is still unlikely to obtain permission from a manufacturer since this reference uses the same approach as the prior art in forming an identifier in board's non-conductive portion, and it expensively requires a special machine to form and read these holes.
BRIEF SUMMARY OF THE INVENTION
Accordingly, it is an exemplified object of the present invention to provide a method for identifying a printed-wiring board without marring board's external appearance, a printed-wiring board treated by this identifying method, and a method for manufacturing such a printed-wiring board.
In order to achieve the above objects, a printed-wiring board of one aspect according to the present invention to be mounted with a circuit element includes a plurality of pads which assist in an electric connection between the circuit element and a wiring pattern, at least one of the plurality of pads being used to serve as an identifier for identifying the printed-wiring board. This printed-wiring board uses pads originally provided to the printed-wiring board to identify the printed-wiring board. In addition, it may identify the product part since it is mounted with the circuit element, such as a semiconductor chip. A print board module including the printed-wiring board mounted with the circuit element and an electronic device, such as a PC, having such a print board module exhibit similar operations.
The plurality of pads may include a first pad to be mounted with the circuit element, and unobservable after the circuit element is mounted thereto, and a second pad not to be mounted with the circuit element, the identifier being determined based on a position of the second pad. Use of the position of the second pad that is not to be mounted with the circuit element to indicate the identifier does not require the circuit element to be removed from the printed-wiring board but enables the printed-wiring board to be identified with the circuit element mounted onto the printed-wiring board. This second pad may be called a dummy pad.
The plurality of pads include a pad having a first shape, and a pad being located at a specific position and having a second shape different from the first shape, and wherein the identifier is determined based on the specific position and/or the second shape. This printed-wiring board changes pad's shape and are identifiable based on the specific position or the second shape. The position of the pad is, for example, a coordinate position from a preset origin, while the shape of the pad is, for example, a circle. Here, “based on” includes derivatives of the position and/or the second shape, such as a position determined by the specific position, e.g., a position next to or above the specific position. The first and second shapes are, for example, a circle, a rectangle, a pentagon, a hexagon, an octagon, and a cross.
At least one of the plurality of pads are provided with and protected by a protective mask that has an opening smaller than a contour of at least one of the plurality of pads, through which opening the circuit element is electrically connectible to at least one of the plurality of pads. This printed-wiring board sets the second shape to the pad provided with the protective mask, such as a SMD (Solder Mask Definition) pad, and maintains the stable electric connection between the circuit element and the pad unless a shape of the opening is changed in the protective mask on the pad. This aspect of the present invention is preferable, for example, to a change of a shape of a pad that has no protective mask, such as an NSMD or NON-Solder Mask Definition pad, since such a pad is expected to use its entire surface for electric connection with the circuit element and has already been designed to be optimal to the electric connection.
The plurality of pads may include a pad having a first shape, and a plurality of pads forming a specif
Fujitsu Limited
Paladini Albert W.
Staas & Halsey , LLP
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