JPH04312961A - Printed circuit board - Google Patents

Abstract

PURPOSE:To increase a mount density of components and to facilitate an inspection by specifying the width of a line for coupling an inspection pad disposed at a 2.54mm lattice to a pad for connecting an integrated circuit, a minimum interval of the circuits, and a rectangular area including lands, and the pads. CONSTITUTION:A printed circuit board for mounting a surface mount type integrated circuit having 80 pins with 0.5mm of a terminal pitch and having a line 2 less than 0.25mm of a line width, has inspection lands 3 disposed on a 2.54mm lattice near the pins of the integrated circuit. A pattern in which the width of the line 2 for coupling the land 3 to a pad 1 for connecting the land 3 to the integrated circuit is 0.25mm, the minimum interval of the circuits is 0.25mm, and an area of a rectangle including the land, the line, and the pads is 10.90cm<2> or less, is provided. Here, the twenty pads 1 are aligned at upper, lower, right and left sides at a reference point 4 as a center, and a pitch between the pads is 0.5mm.

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-mounted integrated circuit is mounted, and more particularly to a circuit pattern within an area occupied by a testing land from an integrated circuit connection pad.

0002

2. Description of the Related Art Conventionally, printed wiring boards used for mounting surface-mounted integrated circuits of this type have integrated circuit connection pads 1 and test lands 3 on an insulating layer 5, as shown in FIG. They were formed by connecting with land 2 in accordance with the established design standards.

0003

The conventional printed wiring board described above has the following drawbacks.

(1) When the test land 3 is placed on a 2.54 mm grid, the area occupied on one printed wiring board is reduced because the distance from the integrated circuit connection pad 1 to the test land 3 is long. The mounting density of components cannot be increased significantly. Also, if the inspection land is removed from the 2.54mm grid in order to reduce the area, a general-purpose wiring inspection machine cannot be used.
Inspection costs will increase.

(2) The width of line 2 is the same narrow width as other signal lines subject to design standards (for example, 0.13 m).
m), the yield is poor and it is necessary to perform a wiring inspection between the integrated circuit connection pad 1 and the inspection land as well.

[0006] An object of the present invention is to provide a printed wiring board that eliminates these drawbacks, increases the mounting density of components, and facilitates inspection.

[0007]

[Means for Solving the Problems] The present invention provides a printed wiring board that mounts an 80-pin surface mount integrated circuit with a terminal pitch of 0.5 mm and has lines with a line width of less than 0.25 mm. 2. near each pin of the integrated circuit;
It has test lands arranged in a 54 mm grid, and the width of the line connecting these lands and the integrated circuit connection pads is 0.
．． 25mm, the minimum gap between these circuits is 0.25mm, and the rectangular area including the land, line, and pad is 1.
It is characterized by having a pattern of 6.52 cm2 or less.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a plan view of an embodiment of the present invention. The integrated circuit connection pads 1 are arranged in rows of 20 on each side around the reference point 4, and the pitch between the pads is 0.5 mm.
It is. The test lands 3 on the 2.54 mm grid are located in the outer shape of the integrated circuit connection pads 1, and are arranged in two rows. The line 2 connects the test land 3 and the integrated circuit connection pad 1, 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 test land 3.

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

Here, (,) is the starting point, [,] is the bending point,
{,} represents the end point, 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
, 6.850) [-10.414, 15.494]
[-10.414, 13.970] [-10.16
0,13.653] [-4.250, 8.58
6] {-11.430, 16.510}・(-3.75
0, 6.850) [-8.890, 13.653]
[-3.750, 9.100] {-8.890
,13.970}・(-3.250, 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, 15.49
4] [-5.334, 13.970] [-5.08
0,13.653] [-2.250,10.693
] {-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) [ 1.27
0,13.653] [0.250,12.69
6] { 1.270, 13.970}・( 0.7
50, 6.850) [ 2.286, 15.49
4] [ 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, 1
3.653] [ 1.750, 11.155] {
3.810, 16.510}・( 2.250,
6.850) [6.350, 13.653]
[ 2.250, 10.642] { 6.350
,13.970]・(2.750, 6.850
) [ 7.366, 15.494] [ 7.3
66,13.970] [7.620,13.653
] [ 2.750, 10.128] { 6.3
50, 16.510}・( 3.250, 6.5
80) [ 8.890, 13.653] [ 3
．． 250, 9.615] { 8.890, 13.
970}・(3.750, 6.850)[
9.906,15.494] [9.906,1
3.970] [10.160, 13.653] [
3.750, 9.101] { 8.890, 1
6.510}・(4.250, 6.850)[
11.430, 13.653] [ 4.250,
8.588] {11.430, 13.970}・(
4.750, 6.850) [12.446,1
5.494] [12.446, 13.970] [1
2.700, 13.653] [ 4.750,
8.075] {11.430, 16.510} Each of the coordinate values mentioned above is 1/4 of the coordinate of line 2, and the remaining coordinate values are the coordinate values described with reference point 4 as the origin,
It can be obtained by rotating 90 degrees, 180 degrees, and 270 degrees. Furthermore, in order to place the inspection land 3 on a 2.54 mm grid, the coordinate values (X, Y) of the reference point 4 from the substrate origin (not shown) are as follows, where m and n are integers and the unit is millimeters. It is expressed as follows.

[0011] X=2.54n+1.27 Y=2.54m+1.27

[Effects of the Invention] As explained above, the present invention has the following effects.

(1) The area occupied by the surface mount integrated circuit having the inspection land on the printed wiring board is 10.90 cm.
2 or less, the packaging density increases by 34% or less compared to the conventional method.

(2) Since the inspection land is placed on a 2.54 mm grid, a general-purpose wiring inspection machine can be used. In particular, this effect is significant because direct inspection of pads with a pitch of 0.5 mm requires expensive inspection equipment and also poses quality problems due to unstable contact.

(3) The width of the line connecting the integrated circuit connection pad and the test land can be made thicker than in conventional circuit patterns, and the spacing between them can be made wider, so there are no problems such as open or short circuits, and this line can be easily wiring test can be omitted.

[Brief explanation of 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]

1 (Integrated circuit) connection pad 2 Line 3 Inspection land 4 Reference point 5 Insulating layer

Claims (1)

[Claims] [Claim 1] An 80-pin surface mount integrated circuit with a terminal pitch of 0.5 mm is mounted, and the line width is 0.25 m.
A printed wiring board having lines of less than m has test lands arranged in a 2.54 mm grid near each pin of the integrated circuit, and the width of the line connecting these lands and the integrated circuit connection pads is 0. .25 mm, the minimum gap between these circuits is 0.25 mm, and the printed wiring board has a pattern such that the rectangular area including the lands, lines, and pads is 16.52 cm2 or less.