JPH04293168A - Reducing method for unused pad - Google Patents

Abstract

PURPOSE:To shorten the work time, and also, to decrease the miss by detecting automatically an unused pad without executing a manual work, and reducing automatically a size of the detected pad. CONSTITUTION:A CAD system is constituted of an input device 1, an output device 2, a storage device 3 and a computer 4. In such a state, by putting an ASC cord to each of parts pins which a printed board designed by the CAD system has, and replacing the parts pin having an unused pad with an unused ASC cord 33 in which the pad diameter is small, a reduction processing of the pad is executed in the CAD system. In such a way, as for the parts having an unused pad in the CAD system, the pad diameter is reduced by replacing the ASC cord, therefore, the reducing work of the pad becomes a work in the CAD which does not necessitate a person's help. Accordingly, the work time is shortened, and also, a miss decreases, and the yield of the printed board can be improved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for reducing unused pads when designing a printed circuit board using a CAD system.

0002

2. Description of the Related Art In designing printed circuit boards, if the diameter of an unused pad is larger than necessary, the wiring pattern is likely to cause pattern bridging through the unused pad, resulting in poor yield. Therefore, in the process of designing a printed circuit board, the pads of unused pins are reduced in size. Conventionally, the pad size of unused pins has been reduced using the following procedure. First, based on the component pin data in the CAD data (hereinafter referred to as "part"), the operator visually searches for component pins that are not connected to the pattern. Alternatively, unused pins are manually found based on the unused pin list. Here, the unused pin list is a list obtained by calculating the difference between the connection data of the CAD data and the pin number of the symbol itself, and outputting unused component pins. Then, the operator operates the found component pins on the display screen of the CAD system to reduce the pad size.

However, in this pad reduction method, unused pins are visually detected and the pad size is reduced manually, so that the process (1) takes a long time. ■Since there is room for human error, the benefits of designing with a CAD system are halved. There was a problem. In particular, when the board is a multilayer board, point (2) becomes a problem compared to single-sided or double-sided boards.

0004

[Problems to be Solved by the Invention] The present invention has been made to solve these problems, and it automatically detects unused pads without manual work, and displays the detected pads. By automatically reducing the size,
The present invention is characterized by realizing a method for reducing unused pads in a short working time and with fewer mistakes.

[0005]

SUMMARY OF THE INVENTION The present invention is a method for reducing unused pads as follows. (1) A method for reducing unused pads in the work of designing a printed circuit board using a CAD system, which comprises the following steps. ■ASC table created in advance
The process of reading the bull and APT table from the memory of the CAD system. Here, the APT table is created by creating an APT code by encoding the various sizes prepared for the printed circuit board pattern and pad, and
A table is created by associating the code with the pattern and pad size. In addition, the ASC table attaches APT codes to pads at each level of through holes for components formed on a multilayer printed circuit board, and these APT
An ASC code is attached to the combination of codes, and this AS
A table is created by associating the C code with the APT code of the pad at each level. ■The process of creating a list of ASC codes used for component pins and through-holes in the CAD data actually designed using the CAD system. ■ The ASC table read in the process of ■ and ■
A process of comparing the list of ASC codes created in step 2 and creating a list of unused ASC codes. ■When creating the above-mentioned ASC table, if the APT code is of a type that cannot be marked to indicate that it is a thermal land, it is located on the inverted inner layer of the printed circuit board and is not attached to the thermal land. AS using a thermal APT cord attached to
The process of importing C code from an external file. Here, the inversion inner layer is a layer in which the inversion pattern of the pattern shown on the CAD data becomes the actual substrate pattern. ■CAD
The process of extracting component pin data from the data and detecting component pins that do not have connections at each level that forms each layer of the board. At this time, a component pin without a pattern is regarded as a component pin without a connection. Additionally, component pins using thermal APT cords are considered to have connections. ■ For component pins that have pads that do not have connections detected in the process of ■, change their ASC codes to
A process of first creating an ASC cord with a reduced pad diameter selected from the list of unused cords created in step (2), and then replacing it with this cord. (2) The method according to (1), wherein the reduction of the pad diameter includes reduction until the pad diameter becomes zero.

[0006]

[Operation] In the present invention, an ASC code is attached to each component pin of a printed circuit board designed using a CAD system, and component pins with unused pads are replaced with unused ASC codes with small pad diameters. - By replacing the pad with a pad, the pad is reduced within the CAD system.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below with reference to the drawings. Figure 1
1 is a diagram showing an example of the configuration of a CAD system for implementing the method according to the present invention. In FIG. 1, 1 is an input device, 2 is an output device, 3 is a storage device, and 4 is a computer.

In the input device 1, numeral 11 is a graphic input section for inputting graphic data of a printed circuit board. Output device 2
, 21 is a display section on which a printed circuit board designed by a CAD system is displayed. In the storage device 3, 31 is a CAD data memory in which graphic data etc. input from the graphic input section 11 are stored. 32 is an ASC table/APT table memory that stores the ASC table and APT table created in advance, and 33 is an unused ASC code stored in the memory 32. unused ASC code memory for storing ASC codes;
34 is an ASC code that uses a thermal APT code.
This is a thermal ASC code memory that stores the code. Although the memories 31 to 34 are shown separately for convenience of explanation, they may be integrated into one memory.

[0009] Here, various sizes of printed circuit board patterns and pads are defined as apertures, and the APT code is a code for this. For example, assume that pads with land diameters of 2 mm, 4 mm, and 2.5 mm have APT codes of 1, 2, and 3, respectively. and,
An APT table is a table in which APT codes are associated with patterns and pad sizes. In addition, each layer constituting a multilayer printed circuit board has a level, and an APT code is attached to a pad on each level for one through hole for a component formed on the printed circuit board, and these APT codes are combined. That is the ASC code. For example, in Figure 2, the level 1 layer is 2 mm,
A combination in which the pad diameter is 4 mm in the level 2 layer is defined as ASC code 1, and a combination in which the pad diameter is 4 mm in the level 1 layer and 2 mm in the level 2 layer is defined as ASC code 2. An ASC table is a table in which the ASC codes defined in this way are associated with the APT codes of pads at each level. In addition,
The ASC table and APT table may exist within the CAD data, or may exist independently from this data. The thermal APT code is drawn in a shape where diagonal lines are not connected to the corresponding layer as shown in Figure 3 on the graphic data handled by the CAD system, but on the actual board it is drawn. All the layer parts are reversed to look like FIG. 4, and this is a cord attached to a pad that becomes a function land that connects to another part, such as a ground plane. This is called an inverted connection. Further, the layer within the substrate to be invertedly connected is referred to as an inverted inner layer.

In the computer 4, numeral 41 is a control section that controls the entire system, and 42 is a pad reduction section that reduces the pads of unused pins. Reduction in this case also includes reduction in which the pad diameter is reduced to zero. In the pad reduction unit 42, 421 is an ASC code list creation means, which assigns ASC codes to component pins and through-holes on the actual board from the printed circuit board graphic data input from the graphic input unit 11. The ASC codes listed are compiled into a list and stored in the CAD data memory 31. 422 stores the list of ASC codes from the CAD data memory 31 into the ASC table/A
Reading means reads out the ASC table from the PT table memory 32, and comparison means 423 compares the list of ASC codes read out by the reading means 422 with the ASC table. 424 creates a list of unused ASC codes based on the comparison results of the comparison means 423;
Unused AS stored in the unused ASC code memory 33
It is a C code creation means. 425 is a connection detection means for detecting the connection of component pins on the printed circuit board being designed based on the contents of the CAD data memory 31 and the thermal ASC code memory 34; 426 is a connection detection means This pad reduction means reduces the pad size of a component pin having an unused pad based on the detection result of the means 425.

[0011] Using such a CAD system, the size of unused pads is reduced by the following procedure. FIG. 5 is a diagram showing an example of the configuration of a printed circuit board to be subjected to reduction processing. This substrate is composed of three layers: level 1, level 2, and level 3. Level 1 is the surface layer of the substrate, level 2 is the inner layer having function lands and inverted connection, and level 3 is the back layer of the substrate. P1,
P 2 and P 3 are component pins. 6 and 7 show the ASC table and APT table created in advance. APT code 3 in FIG. 6 is a thermal APT code. The pad reduction process for such a printed circuit board will be explained step by step. (Operation 1) ■ First, read the part and read the ASC table and APT table that were created in advance. ■Make a list of the ASC codes used for each component pin and through-hole based on the read parts. In the board of Figure 5, component pins P1 and P
ASC code 1 is assigned to pin P2, and ASC code 2 is assigned to component pin P3. Therefore, the created ASC code
The list of codes is as shown in Figure 8. (Operation 2) Next, compare the ASC table read in (Operation 1) ■ with the ASC code list created in (Operation 1) ■, and check the unused ASC codes. Create a list. This list is based on the ASC code in the ASC table in Figure 6.
This corresponds to the part excluding codes 1 and 2. (Operation 3) Furthermore, the ASC code using the thermal APT code which is invertedly connected on the inner layer of the board is read from the thermal ASC code memory 34. (Operation 4) Here, only component pin data in the part is extracted, and only component pins that have no connection with a pattern are detected for each level. At this time, the service obtained in (operation 3)
Even if component pins that use multi-purpose APT codes are not connected to the pattern on the component pin data, the pattern will be reversed and connected on the actual board, so the pattern
It is assumed that there is a connection with the This process of assuming that there is a connection is only necessary when defining the ASC code if the APT code is in a format that cannot be marked as a thermal land. . In addition, component pins that do not have a pattern are regarded as component pins that do not have a connection. (Operation 5) Next, the following processing is performed according to the component pin connection data detected in (Operation 4). ■For component pins that are not connected at all levels, select an ASC code with only the land diameter required for component insertion or component mounting from the list of unused ASC codes created in (operation 2), and use that ASC code. Attach the code. ■For component pins that are unconnected at some levels, select an ASC code with the pads reduced by that level from the list of unused ASC codes created in (operation 2), and use that ASC code. -Add a C. Note that the component pins that are connected at all levels are the same as before. In the printed circuit board of FIG. 5, the component pin P1 is not connected at level 3, so an APT code 100 is attached, which is the APT code of this level set to 4. Since the component pin P2 is not connected at level 1 and level 3, an APT code 101 with the APT code of these levels set to 4 is attached. Since the component pin P3 is not connected at level 1 and level 3, an APT code 102 with the APT code of these levels set to 4 is attached. By replacing the ASC code in this manner, the pads of the printed circuit board are reduced in size within the CAD system as shown in FIG.

0012

According to the present invention, component pins with unused pads in the CAD system are replaced with ASC codes to reduce the pad diameter. This allows pad reduction work to be done in CAD without manual intervention.
It is possible to realize a method of reducing unused pads that takes less time and causes fewer mistakes, and it is possible to improve the yield of printed circuit boards.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of the configuration of a CAD system for implementing the method according to the present invention.

FIG. 2 is an explanatory diagram of an ASC code.

FIG. 3 is an explanatory diagram of a thermal APT code.

FIG. 4 is an explanatory diagram of a thermal APT code.

FIG. 5 is an explanatory diagram showing a processing procedure of a method according to the present invention.

FIG. 6 is an explanatory diagram showing the processing procedure of the method according to the present invention.

FIG. 7 is an explanatory diagram showing a processing procedure of a method according to the present invention.

FIG. 8 is an explanatory diagram showing the processing procedure of the method according to the present invention.

FIG. 9 is an explanatory diagram showing a processing procedure of a method according to the present invention.

[Explanation of symbols]

1 Input device 11 Graphic input section 2 Output device 21 Display section 3 Storage device 31 CAD data memory 32 ASC table/APT table memory 33
Unused ASC code memory 34 Thermal AS code memory 4 Computer 41 Control section 42 Pad reduction section 421 ASC code list creation means 422 Reading means 423 Comparison means 424 Unused ASC codes Creation means 425 Connection detection means 426 Pad reduction means

Claims (2)

[Claims] 1. A method for reducing unused pads in a work of designing a printed circuit board using a CAD system, the method comprising the following steps. ■The process of reading out the ASC table and APT table created in advance from the memory of the CAD system. Here, the APT table is created by creating an APT code by encoding the various sizes available for the printed circuit board pattern and pad.
This APT code is made into a table by associating it with the pattern and pad size. Also, ASC
The table has an APT code attached to the pad at each level of the component through hole formed on the multilayer printed circuit board, an ASC code attached to the combination of these APT codes, and this ASC code. A table is created by associating the codes with the APT codes of the pads at each level. ■The process of creating a list of ASC codes used for component pins and through-holes in the CAD data actually designed using the CAD system. ■ A process of comparing the ASC table read in step (■) with the list of ASC codes created in step (■) and creating a list of unused ASC codes. ■When creating the ASC table, if the APT code is of a type that cannot be marked to indicate that it is a thermal land, it is located on the inverted inner layer of the printed circuit board.
The process of importing the ASC code that uses the thermal APT code attached to Maruland from an external file. Here, the inverted inner layer corresponds to the pattern shown on the CAD data.
In this layer, the inverted pattern of the pattern becomes the actual substrate pattern. ■The process of extracting component pin data from CAD data and detecting component pins that do not have connections at each level forming each layer of the board. At this time, a component pin without a pattern is regarded as a component pin without a connection. Additionally, component pins using thermal APT cords are considered to have connections. ■ Component pins with pads that do not have connections detected in the process of
The process of first creating an ASC cord with a reduced pad diameter selected from the list of unused cords created in step (■), and replacing it with this cord. 2. The reduction of the pad diameter is performed when the pad diameter is 0.
2. The method of claim 1, further comprising reducing the method to .