JP2638318B2 - Printed wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board on which a surface mount type integrated circuit is mounted, and more particularly, to a circuit pattern in an area occupied by an inspection land from a pad for connecting an integrated circuit.

[0002]

2. Description of the Related Art Conventionally, a printed wiring board used for mounting a surface mount type integrated circuit of this type has an integrated circuit connecting pad 1 and an inspection land 3 on an insulating layer 5 as shown in FIG. It was formed by connecting with the land 2 in accordance with the given design standard.

[0003]

The above-mentioned conventional printed wiring board has the following disadvantages.

(1) When the test lands 3 are placed on a grid of 2.54 mm, the distance from the integrated circuit connection pads 1 to the test lands 3 is long, so that the area occupied in one printed wiring board is increased. The mounting density of components does not increase significantly. If the inspection land is removed from the 2.54 mm grid to reduce the area, a general-purpose wiring inspection machine cannot be used.
Inspection costs rise.

(2) The width of the line 2 is the same as the width of other signal lines (for example, 0.13 m), which is restricted by design criteria.
m), the yield is poor, and it is necessary to conduct a wiring test between the integrated circuit connection pad 1 and the inspection land.

An object of the present invention is to provide a printed wiring board which eliminates such disadvantages, increases the mounting density of components, and facilitates application of inspection.

[0007]

According to the present invention, there is provided a printed wiring board on which an 80-pin surface-mounted integrated circuit having a terminal pitch of 0.5 mm is mounted and having a line width of less than 0.25 mm. 1. near each pin of the integrated circuit
It has test lands arranged in a 54 mm grid, the width of the line connecting these lands and the integrated circuit connection pads is 0.25 mm, and the minimum gap between these circuits is 0.25 mm
Yes, including the lands, lines, and pads

[0008]

FIG. 1 is a plan view of an embodiment of the present invention. The integrated circuit connection pads 1 are arranged 20 each in the upper, lower, left and right directions around the reference point 4, and the pitch between the pads is 0.5 mm.
It is. The inspection lands 3 on the 2.54 mm grid are located on the outer shape of the integrated circuit connection pads 1 and are arranged in two rows. The line 2 connects the inspection land 3 and the integrated circuit connection pad 1, and the starting point of the line 2 is the center of the integrated circuit connection pad and the end point is the center of the inspection land 3.

When the reference point 4 of this embodiment is set as the origin of the coordinate value (0, 0), the coordinate values of the starting point, the bending point, and the ending point are as follows.

Where (,) is the starting point, [,] is the inflection point,
｛And｝ represent end points, and the unit of each number is millimeter. -(-4.750, 6.850) [-11.430, 13.653] [-4.750, 8.073] {-11.430, 13.970}-(-4.250, 6.970) 850) [-10.414, 15.494] [-10.414, 13.970] [-10.160, 13.653] [-4.250, 8.586] ｛-11.430, 16. 510}-(-3.750, 6.850) [-8.890, 13.653] [-3.750, 9.100] {-8.890, 13.970}-(-3.250, 6.970) 6.850) [-7.874, 15.494] [-7.874, 13.970] [-7.620, 13.653] [-3.250, 9.613]}-8.890, 16.510}-(-2.750 6.850) [-6.350, 13. 653] [-2.750, 10.126] {-6.350, 13.970} (-2.250, 6.850) [-5.334, 15.494] [-5.334, 13] .970] [-5.080, 13.653] [-2.250, 10. 639 ] {-6.350, 16.510}-(-1.750, 6.850) [-3.810, 13.653] [-1.750, 11.152] {-3.810, 13 .970}-(-1.250, 6.850) [-2.794, 15.494] [-2.794, 13.970] [-2.540, 13.653] [-1.250, 11.665] {−3.810, 16.510} • (−0.750, 6.850) [−1.270, 13.653] [−0.750, 12.175]} − 1.270 , 13.970}-(-0.250, 6.850) [-0.254, 15.494] [-0.254, 13.970] [-0.250, 12.707] {-1. 270, 16.510} (0.250, 6.850) [1.270, 13 0.653] [0.250, 12.696] {1.270, 13.970} (0.750, 6.850) [2.286, 15.494] [2.286, 13.970] [ 2.540, 13.653] [0.750, 12.182] {1.270, 16.510}-(1.250, 6.850) [3.810, 13.653] [1.250, 11.668] {3.810, 13.970} • (1.750, 6.850) [4.826, 15.494] [4.826, 13.970] [5.080, 13.653] [1.750, 11.155] {3.810, 16.510} • (2.250, 6.850) [6.350, 13.653] [2.250, 10.652]} 6.350 , 13.970] · (2.750 6.850) [7.366, 15.494] [7,366, 13.970] [7.620, 13.653] [2.750, 10.128] {6.350, 16.510} (3.250, 6.580) [8.890, 13.653] [3.250, 9.615] {8.890, 13.970} • (3.750, 6.850) [9.906 , 15.494] [9.906, 13.970] [10.160, 13.653] [3.750, 9.101] {8.890, 16.510} • (4.250, 6.850) ) [11.430, 13.653] [4.250, 8.588] {11.430, 13.970} • (4.750, 6.850) [12.446, 15.494] [12. 446, 13.970] [12. 00, 13.653] [4.750, 8.075] {11.430, 16.510} Each of the coordinate values described above is a quarter of the coordinate of the line 2, and the remaining coordinate values are described as The obtained coordinate values can be obtained by rotating 90 °, 180 °, and 270 ° with reference point 4 as the origin. The inspection land 3 is 2.54 m
The coordinate values (X, Y) of the reference point 4 from the substrate origin (not shown) to be placed on the grid of m are expressed as follows, where m and n are integers and the unit is millimeters.

X = 2.54n + 1.27 Y = 2.54m + 1.27

As described above, the present invention has the following effects.

(1) The area occupied by the surface mount type integrated circuit having the inspection land on the printed wiring board is 10.90 cm.
^{When it is 2} or less, it becomes 34% or less as compared with the conventional one, so that the mounting density increases.

(2) Since the inspection lands are on the 2.54 mm grid, a general-purpose wiring inspection machine can be used. In particular, in order to directly inspect a pad having a pitch of 0.5 mm, an expensive inspection apparatus is required, and there is a problem in quality due to unstable contact and the like.

(3) The line connecting the pad for connecting the integrated circuit and the inspection land can be made wider than the conventional circuit pattern, and the interval between them can be widened, so that there is no trouble such as open / short, and this line portion Can be omitted.

[Brief description of the drawings]

FIG. 1 is a plan view of a printed wiring board according to an embodiment of the present invention.

FIG. 2 is a plan view of an example of a conventional printed wiring board.

[Explanation of symbols]

 Reference Signs List 1 (integrated circuit) connection pad 2 line 3 inspection land 4 reference point 5 insulating layer

Claims (1)

(57) [Claims] 1. An 80-pin surface-mount integrated circuit having a terminal pitch of 0.5 mm is mounted and has a line width of 0.25 mm.
In a printed wiring board having less than one line, a plurality of inspection lands arranged in a grid of 2.54 mm are provided near each pin of the integrated circuit, and the width of a line connecting these lands and the pads for connecting the integrated circuit is 0. 25 mm, the minimum gap between these circuits is 0.25 mm, including the lands, lines and pads Printed wiring board.