JP2004319692A - Electronic circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an electronic circuit board wherein reliability over external force of a grid array package joint is improved without causing cost raise. <P>SOLUTION: The electronic circuit board is provided with pads for connection which are arranged at positions corresponding to the respective terminals of a grid array package in order to mount the grid array package having a large number of the terminals which are arranged to matrix shape, a wiring pattern which is led out in a specified direction from these pads for connection and has small width to the pads, and a pattern width adjustment part in which wiring width is gently changed from the pads for connection which are positioned at least on the outermost series of the terminals of the grid array package and which is connected to the corresponding wiring pattern. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electronic circuit board for mounting a grid array package having a large number of terminals arranged in a matrix.
[0002]
[Prior art]
In recent years, for example, as seen in the spread of mobile phones, the size of electronic devices has been further reduced. In support of these developments, there are measures to increase the number of pins, increase heat dissipation, and operate at higher speeds in semiconductor devices. In addition, there is a strong demand for smaller and lighter packages. In order to satisfy these requirements, a grid array package called a BGA (Ball Grid Array) in which solder ball terminals are arranged in a lattice pattern on the back surface of a package from a conventional plastic package using a lead frame has been developed and applied. It has become. The grid array package has such features that the package can be reduced in size, the terminal interval is larger than that of a conventional plastic package, and the substrate can be easily mounted.
[0003]
When mounting such a small grid array package having a large number of terminals arranged in a matrix on an electronic circuit board, soldering is performed after mounting the ball terminals on the package side on the connection pads on the board side. . Conventionally, the shape of the connection pad is a perfect circle or an ellipse. When an elliptical connection pad is used, a large number of thin wiring patterns for putting signals in and out of the package and other components can be drawn out from between the connection pads (for example, see Patent Document 1).
[0004]
[Patent Document 1]
JP 2001-230533 A (Pages 9-11, FIGS. 2 and 18)
[0005]
[Problems to be solved by the invention]
The conventional electronic circuit board on which a grid array package in which a large number of terminals are arranged in a matrix is mounted is configured as described above, so that when the grid array package is soldered, it is soldered to a thin wiring pattern. Spreads. For example, when an external force is applied to the electronic circuit board in a direction perpendicular to the electronic device by, for example, pressing an operation button of a portable device, the electronic circuit board tends to bend at the outermost row of the terminals of the grid array package. For this reason, there has been a problem that a crack is generated from a thin solder-attached portion spread to a thin wiring pattern radially drawn from the grid array package. In addition, the connection pads after mounting the grid array package are thicker than the lead wiring because of the thickness including the joining solder, and the external force is concentrated at the root of the lead wiring, and the lead wiring with a narrow wiring width However, there was a problem of disconnection. In order to prevent solder cracks in these wiring patterns and disconnection of wiring patterns, reinforcement such as applying an underfill is required, which leads to an increase in material costs and manufacturing processes, resulting in higher costs. was there.
[0006]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object to obtain an electronic circuit board for mounting a grid array package that improves the reliability of a grid array package junction without increasing costs. And
[0007]
[Means for Solving the Problems]
An electronic circuit board according to the present invention includes a connection pad provided at a position corresponding to each terminal of a grid array package for mounting a grid array package having a large number of terminals arranged in a matrix, A wiring pattern which is drawn out of the pad in a predetermined direction and has a wiring pattern having a narrow width with respect to the connection pad, the wiring is gently wired from the connection pad located at least in the outermost row of the terminals of the grid array package. It is provided with a pattern width adjustment unit that changes the width and connects to the corresponding wiring pattern.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
Embodiment 1 FIG.
FIG. 1 is a partial plan view showing a portion on which a grid array package is mounted on an electronic circuit board according to Embodiment 1 of the present invention. FIG. 2 is an explanatory diagram showing an enlarged part A of the electronic circuit board of FIG. FIG. 3 is a sectional view taken along the line BB of FIG. 1 showing a state where the grid array package is mounted on the electronic circuit board.
A large number of connection pads 11 are provided on the electronic circuit board 10 so as to be joined to the ball terminals 21 of the grid array package 20. A thin strip-shaped wiring pattern 13 is provided from the connection pad 11 so as to be electrically connected to another component or the like. A through hole 14 is provided in the electronic circuit board 10 in the middle of the arrangement of the connection pads 11 as shown in the figure, and the connection pad 11 is electrically connected to another component through the through hole 14. It has become. Between the connection pad 11 and the wiring pattern 13 located in the outermost row of the terminals of the grid array package 20, a pattern width adjustment unit 13a in which the wiring width gradually changes from the connection pad 11 and connects to the corresponding wiring pattern 13 Is formed. In FIG. 1, the pattern width adjustment unit 13a is applied only to the outermost row of the terminals of the grid array package, but may be applied to other connection pads. Reference numeral 20a denotes an edge of the grid array package 20.
[0009]
On the electronic circuit board 10, a solder resist 12 constituting an insulating layer of, for example, epoxy resin is applied over the outside of the mounting position of the grid array package 20, and the wiring pattern 13 is electrically unnecessary unnecessarily. Try not to connect. The solder resist 12 has an opening 12 a at the connection pad 11 for soldering with the ball terminal 21 of the grid array package 20. The area size of the solder resist opening 12a is slightly larger than the size of the connection pad 11, and includes the connection pad 11 and a part of the pattern width adjustment unit 13a as shown in FIG. The pattern exposure part 15 is formed.
[0010]
As shown in FIG. 3, when the grid array package 20 is mounted on the electronic circuit board 10 and soldered, the solder 30 spreads over the area of the solder resist opening 12 a and the pad 11 which is the pattern exposed portion 15 It is welded to the pattern width adjusting part 13a.
Generally, when an external force is applied to the electronic circuit board perpendicularly by pressing an operation button or the like, the electronic circuit board tends to bend at the outermost row of the terminals of the grid array package. As is clear from FIG. 2B, the width dimension of the pattern width adjusting portion 13a of each pattern exposure portion 15 positioned in parallel with the outermost row of the terminals of the grid array package 20 is equal to the original width of the wiring pattern 13. Since the width of the solder is larger than that of the solder, the strength is increased by increasing the width of the solder deposited on the pattern exposed portion 15. Therefore, cracking of the solder 30 is prevented. The pattern width adjusting portion 13a covered with the solder resist 12 is wider than the wiring pattern 13 and thus has higher rigidity, and the difference in rigidity from the solder exposed pattern exposed portion 15 becomes smaller, so that the vicinity of the solder resist opening 12a is reduced. Concentration of external force on This delays the generation of cracks in the wiring pattern 13 and also increases the time required for the wiring pattern 13 to be broken due to crack propagation, thereby preventing the wiring pattern 13 from being broken.
Since cracking of the solder 30 and disconnection of the wiring pattern 13 can be prevented, reinforcement such as application of an underfill is not required, so that bonding reliability can be improved at low cost.
[0011]
As described above, according to the first embodiment, the pattern width adjustment unit that gradually changes the wiring width from the connection pads located at least in the outermost row of the terminals of the grid array package and connects to the corresponding wiring pattern is provided. Since it is formed, the effect of preventing the solder from being cracked by the external force that the electronic circuit board tends to bend at the outermost row of the terminals of the grid array package can be obtained. Further, when a solder resist is applied so as to form an opening in a portion of each connection pad, a predetermined portion of the pattern width adjustment portion is included in the opening, so the pattern exposure portion is The strength of the solder is increased by welding, so that cracking of the solder can be prevented. In addition, the pattern width adjustment unit has a higher rigidity because it is wider than the wiring pattern, reduces the difference in rigidity with the solder spread part, reduces external force concentration near the solder resist opening, delays crack generation, and In addition, it is possible to prevent the disconnection of the wiring pattern by increasing the time until the disconnection due to crack propagation. Therefore, reinforcement such as applying an underfill is not required, and the effect of improving the reliability of the joint at low cost can be obtained.
[0012]
Embodiment 2 FIG.
FIG. 4 is a partial plan view showing an electronic circuit board according to Embodiment 2 of the present invention, and FIG. 5 is an explanatory view showing a part of the electronic circuit board according to Embodiment 2 in an enlarged manner.
In the first embodiment of the present invention, the wiring pattern width 13a is pulled out from the connection pad 11 in a direction perpendicular to the outermost row of the terminals of the grid array package 20, but in the second embodiment, the pattern width adjusting section 13a A part of the wiring pattern 13 is drawn at a predetermined angle (within 90 degrees) with respect to the outermost row of the terminals of the grid array package 20.
[0013]
In this case, as is clear from FIG. 5B, the width dimension of the pattern exposed portion 15 in the outermost row direction of the terminals of the grid array package 20 in the direction of the wiring pattern 13 is wider than the width of the wiring pattern 13. Become. Therefore, an effect similar to that of the first embodiment is obtained.
In addition, by making the angle of the wiring lead, the length of the solder spread in the peripheral direction of the grid array package 20 can be reduced, and the external force applied to the solder spread boundary with respect to the deformation amount of the conventional electronic circuit board can be reduced. Can be reduced, and the occurrence of cracks in the solder and the wiring pattern 13 can be prevented.
[0014]
As described above, according to the second embodiment, in addition to the first embodiment, the lead-out direction of the pattern width adjustment unit is set to be equal to the outermost row of the grid array package by a predetermined angle in the peripheral direction of the grid array package. And the external force applied to the solder spread boundary can be reduced, and the effect of preventing cracks in the solder and the wiring pattern can be obtained.
[0015]
Embodiment 3 FIG.
FIG. 6 is a partial plan view showing an electronic circuit board according to Embodiment 3 of the present invention, and FIG. 7 is an explanatory diagram showing an enlarged part of the electronic circuit board according to Embodiment 3 of the present invention.
In the figure, in the third embodiment, a pattern having the same width as the diameter of the connection pad 11 is formed up to the edge of the solder resist opening 12a, and the width gradually increases from the edge of the solder resist opening 12a toward the wiring pattern 13. I try to change. FIG. 6 shows a case where the grid array package 20 is pulled out at a predetermined angle with respect to the outermost row of terminals. Also in this case, as shown in FIG. 7B, the width of the pattern exposed portion 15 in the outermost row direction of the terminals of the grid array package 20 in the direction of the wiring pattern 13 is the same as that of the wiring pattern 13. It is wider than the width. Further, the angle of the wiring lead is reduced, so that the spread length of the solder in the peripheral direction of the grid array package 20 can be reduced, and the solder can be removed with respect to the deformation amount of the electronic circuit board to which the present invention is not applied. The external force applied to the spreading boundary can be reduced.
[0016]
As described above, according to the third embodiment, the pattern width adjusting unit sets the width of at least the portion inside the opening of the solder resist to be the same as the diameter of the connection pad. When the width is sufficiently larger than the width of the solder, the effect of reducing the external force applied to the spread boundary portion of the solder and preventing the solder from cracking can be obtained. In addition, since the lead-out direction of the pattern width adjustment unit is different from the direction of the wiring pattern by a predetermined angle, the length of solder spread in the peripheral direction of the grid array package is reduced, and the external force applied to the solder spread boundary is reduced. Thus, the effect of preventing the occurrence of cracks in the solder and the wiring pattern can be obtained.
[0017]
【The invention's effect】
As described above, according to the present invention, a connection pad provided at a position corresponding to each terminal of the grid array package for mounting a grid array package having a large number of terminals arranged in a matrix, In an electronic circuit board having a wiring pattern pulled out from the connection pad in a predetermined direction and having a narrow width with respect to the connection pad, the connection pad located at least in the outermost row of the terminals of the grid array package is gradually loosened. The wiring width is changed so that it has a pattern width adjustment unit that connects to the corresponding wiring pattern, so the external circuit that the electronic circuit board tries to bend at the outermost row of the terminals of the grid array package This has the effect of preventing cracking, and as a result, reinforcement such as applying underfill is not possible. Next, the effect of inexpensively improving the reliability of the junction wants.
[Brief description of the drawings]
FIG. 1 is a partial plan view showing an electronic circuit board according to Embodiment 1 of the present invention.
FIG. 2 is an explanatory diagram showing a part of an electronic circuit board according to the first embodiment in an enlarged manner;
FIG. 3 is a partial sectional view showing a grid array package mounting portion of the electronic circuit board according to Embodiment 1 of the present invention;
FIG. 4 is a partial plan view showing an electronic circuit board according to Embodiment 2 of the present invention.
FIG. 5 is an explanatory diagram showing a part of an electronic circuit board according to the second embodiment in an enlarged manner;
FIG. 6 is a partial plan view showing an electronic circuit board according to Embodiment 3 of the present invention.
FIG. 7 is an explanatory diagram showing an enlarged part of the electronic circuit board according to Embodiment 3;
[Explanation of symbols]
Reference Signs List 10 electronic circuit board, 11 connection pad, 12 solder resist, 12a solder resist opening, 13 wiring pattern, 13a pattern width adjustment unit, 14 through hole, 20 grid array package, 21 ball terminal, 30 solder.

Claims (4)

A connection pad provided at a position corresponding to each terminal of the grid array package for mounting a grid array package having a large number of terminals arranged in a matrix, and pulled out from these connection pads in a predetermined direction, And a wiring pattern having a wiring pattern having a narrow width with respect to the connection pad, wherein the wiring width gradually changes from at least the connection pad located at the outermost row of the terminals of the grid array package. An electronic circuit board, comprising: a pattern width adjustment unit that connects to the electronic circuit board. 2. The electronic circuit according to claim 1, wherein a solder resist is applied so as to form an opening in each connection pad portion, and a predetermined portion of the pattern width adjusting portion is included in the opening. substrate. 3. The electronic circuit board according to claim 2, wherein the pattern width adjusting section has a width of at least a portion inside the opening of the solder resist equal to a diameter of the connection pad. The electronic circuit board according to any one of claims 1 to 3, wherein a drawing direction of the pattern width adjusting unit is different from a direction of the wiring pattern by a predetermined angle.

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