Computer-aided design and analysis of circuits and semiconductor – Nanotechnology related integrated circuit design
Reexamination Certificate
2001-11-29
2003-12-16
Smith, Matthew (Department: 2825)
Computer-aided design and analysis of circuits and semiconductor
Nanotechnology related integrated circuit design
C716S030000, C716S030000
Reexamination Certificate
active
06665854
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to methods and apparatuses of checking the mount quality of a circuit board. More specifically, the present invention relates to a mount quality checking method for designing a circuit board that satisfies the target quality by predicting the quality of the circuit board having electronic components mounted thereon by a mounting device, a method of displaying a virtual 3D image showing a mount state for the mount quality check, and an apparatus using either or both of the methods.
2. Description of the Background Art
Conventionally, for designing a circuit board, designers refer to a design manual or use a design rule check (DRC) in a CAD system for trying to comply with predetermined design standards in order to determine component arrangement positions, pattern shapes, land shapes, and others. Also, the designers manufacture a prototype of a designed circuit board to see if any problem may occur at the time of manufacturing, or the designers have a 2-D image (virtual prototype) showing the mount state of the circuit board displayed on a screen of a computer device to see if any problem may occur or not. Then, the designers give some feedback about the found problem to the design.
By repeating such a designing-to-prototyping (virtual prototyping) process several times like a loop, the mount quality of the circuit board can be ensured when mass-produced.
To further improve the mount quality, some methods are suggested in Japanese Patent Laid-Open Publication Nos. 9-330342 (1997-330342) and 11-175577 (1999-175577) for predicting and checking the mount quality of the circuit board.
In these methods, the mount quality is predicted only from device data such as the shapes of the components and the shapes of the circuit board, that is, without consideration of a variety of mounting devices and mounting processes. In fact, depending on the mounting device to be used, a pitch between mount components can be determined to be a narrow one (if a small nozzle is used or high-precision positioning is possible, for example) or a standard one.
In Japanese Patent Laid-Open Publication No. 11-330784 (1999-330784), a method of checking the mount quality in consideration of a circuit board manufacturing process is disclosed, which is shown in FIG.
37
.
In this method, reference rules for manufacturing are registered in advance in a factory (manufacturing) section. A design section checks designed parts according to design rules which are formulated based on the reference rules.
In the above conventional methods, however, based on the operation requirements of the mounting devices and the requirements of the mount process, the operators have to derive a check value for each check part on the circuit board and refer to the derived check values as manufacturing reference rules. Therefore, if the requirements of the mounting devices, materials, and others are changed, it is not easy to predict how such change will affect the reference rules.
To ensure the mount quality, productivity may have to be decreased in some cases. For example, depending on the mounting device, the operational speed may have to be reduced to ensure accuracy. Also, processing may have to be carried out mainly by a specific facility at the cost of a load balance among the facilities.
On the design side, a plurality of processes may be taken for changing the design to ensure the mount quality. Among these methods, the designer is supposed to appropriately select a highest-productive, lowest-cost method, but he/she may have difficulty doing so at the time of changing the design in consideration of both productivity and cost.
In the conventional method of virtually making a prototype for displaying the mount state of the circuit board on the screen of a computer device, the components are displayed only by two-dimensional plane graphics. Therefore, when two components which differ in their respective upper shapes ((a) of
FIG. 38
) are two-dimensionally displayed, they look the same ((b) of FIG.
38
). Also, when two components which differ in their respective heights ((c) of
FIG. 38
) are two-dimensionally displayed, they look the same ((d) of FIG.
38
). Therefore, a detailed check of the mount requirements as to the shape and height of the components cannot be performed, and a sufficient study therefore cannot be made.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a method of checking the mount quality of a circuit board, a method of displaying the mount state of circuit board in a virtual three-dimensional display, and an apparatus using either or both of the above methods. With these methods and apparatus, if the mounting process to be used, the operation requirement of the mounting device, and others are changed, such a change can be easily reflected on the design check. Therefore, consideration of the mount quality during the mounting procedure reduces the number of quality checks onto the actual prototype, and the circuit board that satisfies the target quality can be designed in the early stage of designing.
The present invention has the following features to attain the object above.
A first aspect of the present invention is directed to a method of checking a mount quality of a circuit board having components mounted thereon by a mounting device, and the method includes the steps of:
receiving board information related to the circuit board to be used in a designed circuit, component information related to the components to be used, and position information related to a mounting position of the component;
receiving a mount requirement specifying a mounting process and a mounting device to be used in manufacturing the circuit board; and
checking, based on a requirement for the mounting process and a requirement for operation of the mounting device, to see whether the circuit board manufactured from the board information, the component information, and the position information under the mount requirement can satisfy a predetermined target mount quality.
As such, in the method according to the first aspect, the requirements are registered in advance for respective mounting processes and mounting devices. When the mounting process to be used and/or the operation requirements for the mounting device is/are changed, the change is easily reflected on a design check. Therefore, consideration of the mount quality during the mounting procedure reduces the number of quality checks onto the actual prototype, and the circuit board that satisfies the target quality can be designed in the early stage of designing.
Preferably, the check in the method according to the first aspect is made based on the requirement for the mounting process and the requirement for operation of the mounting device in order to see whether the circuit board manufactured from the board information, the component information, and the position information under the mount requirement can satisfy a predetermined target productivity.
As such, by checking the mount quality of the circuit board and the productivity (cost), it is possible to design a lower-cost circuit having more productivity and satisfying the requirements for the target mount quality.
Here, the component information includes at least a number, a shape, a packaging, and a size of each of the components. The board information includes at least a material, a shape, a thickness of the board, a land shape, a printed mask shape, and a position correction mark shape of each of the components. The requirement for the mounting process includes at least soldering processes, a soldering material to be used, and a board process/inspection after the components are mounted. The requirement for operation of the mounting device includes at least a mountable component type, a mount accuracy for each of the components, a mount cycle time, and a mountable range. The mount quality is checked as to at least the mounting position of the component, a state of soldering, a board process/inspection a
Fujiwara Hiroaki
Hanada Keiji
Okamoto Masaki
Yokomori Masashi
Liu Andrea
Wenderoth , Lind & Ponack, L.L.P.
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