JP3680398B2 - Printed wiring board - Google Patents

Description

[0001]
【Technical field】
The present invention relates to a printed wiring board in which a large number of printed wiring boards for mounting electronic components are arranged in series or in a grid, and in particular, when an electronic component mounting board is punched out, the insulating substrate of the electronic component mounting board is used. The present invention relates to a printed wiring board capable of preventing the occurrence of cracks.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as an electronic component mounting board, as shown in FIG. 6, a plurality of insulating substrates 31 and 32 are stacked and a mounting portion 51 for mounting an electronic component 8 is provided on the front side surface. . An internal circuit 55 is provided between the insulating substrates 31 and 32.
A bonding pad 52 and an external circuit 53 are provided around the mounting portion 51 on the front side surface of the electronic component mounting board. Further, on the back side surface of the electronic component mounting board 5, a ball pad 59 for mounting the printed wiring board 5 on the external board and a conductor circuit 590 are provided.
[0003]
The external circuits 53 and 590 provided on the front side surface and the back side surface of the electronic component mounting substrate 5 are electrically connected by a through hole 54 penetrating the insulating substrates 31 and 32. Further, a heat radiating through hole 510 is provided at the lower portion of the mounting portion 51. The inner walls of the through holes 54 and 510 are covered with the metal plating film 50, and the inside is filled with a resin 58 for preventing moisture penetration.
[0004]
The front side surface of the electronic component mounting substrate 5 is covered with a solder resist film 39 except for the bonding pads 52. On the other hand, the back side surface of the electronic component mounting substrate 5 is covered with a solder resist film 39 except for the pads 59.
[0005]
An electronic component 8 is mounted on the mounting portion 51 using an adhesive 390. The electronic component 8 and the bonding pad 52 are connected by a bonding wire 81. The electronic component 8 and the bonding wire 81 are sealed with a sealing resin 9.
The electronic component mounting substrate 5 is a ball grid array mounted on an external substrate via solder balls.
[0006]
Next, when mounting electronic components on the electronic component mounting board, as shown in FIG. 7, a printed wiring board 7 in which a large number of electronic component mounting boards 5 are arranged is used.
That is, the printed wiring board 7 is a substrate in which a large number of electronic component mounting substrates 5 are arranged in series or in a grid shape through the cutting slits 2 between the electronic component mounting substrates 5. At one end of each electronic component mounting substrate 5, a metal-plated mold gate portion 6 for introducing a sealing resin around the electronic component 8 is provided.
Next, as shown in FIGS. 6 and 8, the electronic component 8 is bonded to the mounting portion 51 using an adhesive 390, and the electronic component 8 and the bonding pad 52 are connected by a bonding wire 81.
[0007]
Next, as shown in FIG. 9, the sealing resin 9 is supplied from the mold gate portion 6, and the surface of the electronic component provided on the mounting portion 51 of the electronic component mounting substrate 5 is covered with the sealing resin 9. . Next, the electronic component mounting substrate 5 is punched out using a punching die along the outer dimension line 500 of the electronic component mounting substrate 5. As a result, the electronic component mounting board 5 shown in FIGS. 10 and 6 can be obtained.
[0008]
[Problems to be solved]
However, in the conventional printed wiring board, as shown in FIG. 11, cracks 38 may occur in the insulating substrates 31 and 32 of the electronic component mounting substrate 5 during punching. In particular, as shown in FIG. 9, the frequency of occurrence of cracks is particularly high in the corner portion 599 of the electronic component mounting board where shear stress due to the mold is concentrated.
[0009]
As shown in FIG. 11, when the crack 38 reaches the internal circuit 55 provided inside the electronic component mounting substrate 5, the internal circuit 55 and the external circuits 53 and 590 are short-circuited by migration in a humidified atmosphere. . This makes it impossible to use the electronic component mounting board 5.
[0010]
In view of the conventional problems, the present invention provides a printed wiring board in which a large number of electronic component mounting boards are arranged, which can prevent the occurrence of cracks and prevent a short circuit between an internal circuit and a conductor circuit. It is something to try.
[0011]
[Means for solving problems]
According to the first aspect of the present invention, a large number of electronic component mounting substrates for mounting electronic components are arranged, and a cutting slit is provided between each of the electronic component mounting substrates, and is separated from the cutting slit. A printed wiring board in which the electronic component mounting board is punched out by a die along an outer dimension line at a predetermined position ;
A metal-plated mold gate provided at one corner of the electronic component mounting substrate for introducing a sealing resin into the electronic component mounting substrate;
Provided other corner portion of the electronic component carrier is a printed circuit board, characterized in that it comprises a sub-slit extending obliquely from said cutting slit.
[0012]
The effects of the printed wiring board will be described.
Sub-slits extending obliquely from the cutting slits are provided at the corners of the electronic component mounting board. When each electronic component mounting board is punched with a die, it is punched leaving a part of the inner wall of the sub slit. In this case, the mold does not contact the remaining inner wall of the sub slit. The inner wall of the remaining sub-slit becomes a corner portion of the electronic component mounting board. For this reason, the shearing stress of the mold is not applied to the corner portion of the electronic component mounting substrate, and the electronic component mounting substrate is evenly distributed over the entire periphery of the electronic component mounting substrate.
[0013]
Therefore, cracks do not occur in the electronic component mounting board due to the punching process. In particular, there is no risk of cracks occurring at the corners. Therefore, a short circuit between the internal circuit and the conductor circuit due to migration can be prevented. Furthermore, the internal circuit provided inside the electronic component mounting board is not damaged.
[0014]
The length A of the inner wall to be left among the inner walls of the sub slit is preferably 1 to 20 mm (see FIG. 3). If it is less than 1 mm, the pressing force concentrates on the corner portion, which may cause cracks. On the other hand, if it exceeds 20 mm, the size of the sub-slit itself becomes excessive, which hinders downsizing of the printed wiring board.
[0015]
Next, as described in claim 2, the shape of the inner wall of the sub slit may be either linear or curved. In the case of a curved shape, the inner wall of the sub slit is curved in a concave or convex shape with respect to the inner side of the electronic component mounting substrate (see FIGS. 4 and 5). Further, when the inner wall of the sub slit is in the above-mentioned curved shape, it is difficult to generate stress at the time of punching, so that the effect of preventing cracks is particularly great.
Next, as described in claim 3, the sub-slit is preferably rectangular, circular, elliptical, or triangular because slit formation is easy.
[0016]
Next, as described in claim 4, it is preferable to provide a bridge-like connecting portion between the cutting slit and the sub slit. This increases the mechanical strength of the printed wiring board around the cutting slit and the sub slit.
Further, the cutting slit and the sub slit may form one slit continuously.
According to a fifth aspect of the present invention, an electronic component is bonded to the electronic component mounting substrate, and a bonding pad and the electronic component in the electronic component mounting substrate are connected by a bonding wire. In addition, there is a printed wiring board characterized in that an electronic component and a bonding wire mounted on the electronic component mounting substrate are covered with a sealing resin, and each electronic component mounting substrate is punched into individual pieces ( Refer to Embodiment Example 1).
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1
A printed wiring board according to an embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, the printed wiring board of this example is a strip-shaped substrate in which a large number of electronic component mounting substrates 5 for mounting electronic components 8 are arranged in series. A cutting slit 2 is provided between the electronic component mounting substrates 5. Sub-slits 11 and 12 extending obliquely from the cutting slit 2 are provided in the corner portion 50 of the electronic component mounting substrate 5.
[0018]
The sub slits 11 and 12 are substantially rectangular, and the inner walls thereof are linear.
The sub slit 11 is a slit continuous with the cutting slit 2. The sub slit 11 extends in an oblique direction of the cutting slit 2 from the side surface portion 29 of the cutting slit 2. On the other hand, the sub-slit 12 is a slit independent of the cutting slit, and a bridge-like connecting part 57 is provided between the sub-slit 12 and the cutting slit 2.
[0019]
One end of the electronic component mounting substrate 5 is provided with a mold gate portion 6 for introducing a sealing resin at the time of resin sealing.
The electronic component mounting substrate 5 is a square ball grid array, and its structure is the same as the conventional example shown in FIG.
[0020]
A method of mounting an electronic component on the electronic component mounting board using the printed wiring board will be described.
First, as shown in FIG. 1, the electronic component 8 is bonded to the surface of the mounting portion 51 of the electronic component mounting substrate 5 arranged on the printed wiring board 7 by an adhesive. Next, the electronic component and the bonding pad 52 are connected by a bonding wire. Next, as shown in FIG. 2, the sealing resin 9 is introduced from the mold gate portion 6, and the electronic component 8 and the bonding wire mounted on each electronic component mounting substrate 5 are covered with the sealing resin 9 (FIG. 2). 6).
[0021]
Next, as shown in FIG. 1, each electronic component mounting board 5 is individually cut by punching the electronic component mounting board 5 using a punching die along the outer dimension line 500 of the electronic component mounting board 5. Tidy up.
At the time of punching, punching is performed leaving a part of the inner walls of the sub slits 11 and 12. As shown in FIG. 2, the length A of the inner wall to be left among the inner walls of the sub slits 11 and 12 is 1 to 20 mm, and this portion becomes the corner portion 50 of the electronic component mounting substrate 5. Thereby, as shown in FIG. 2, the electronic component mounting board | substrate 5 which mounts an electronic component can be obtained.
[0022]
Next, the function and effect of this example will be described.
As shown in FIG. 1, sub-slits 11 and 12 extending obliquely from the cutting slit 2 are provided at the corner portion 50 of the electronic component mounting substrate 5. Then, as shown in FIG. 2, when each electronic component mounting substrate 5 is punched by a punching die, punching is performed leaving a part of the inner walls of the sub slits 11 and 12. In this case, the mold does not contact the remaining inner walls of the sub slits 11 and 12. The remaining inner walls of the sub-slits 11 and 12 become corner portions 50 of the electronic component mounting substrate 5.
[0023]
For this reason, the shearing stress of the mold is not applied to the corner portion, and the corner portion is evenly distributed over the entire periphery of the electronic component mounting substrate 5. Therefore, no crack is generated in the electronic component mounting board 5 by the punching process. In particular, there is no risk of cracks occurring in the corner portion 50. Therefore, a short circuit between the internal circuit and the external circuit 53 due to migration can be prevented. Further, the internal circuit provided in the electronic component mounting board 5 is not damaged.
[0024]
Further, since the bridge-like connecting portion 57 is provided between the cutting slit 2 and the sub-slit 12, the mechanical strength of the printed wiring board 7 around the both is high. Therefore, it is easy to handle a printed wiring board during various manufacturing processes such as circuit formation. In addition, damage to the printed wiring board can be prevented.
In the printed wiring board of this example, the electronic component mounting substrates 5 are arranged in series, but the electronic component mounting substrates 5 can also be arranged in a grid.
[0025]
Embodiment 2
In the printed wiring board of this example, as shown in FIG. 3, the corner part 50 of the electronic component mounting board 5 has a sub slit 13 extending obliquely from the end of the cutting slit 2.
Others are the same as in the first embodiment.
Also in this example, the same effects as those of the first embodiment can be obtained.
[0026]
Embodiment 3
In the printed wiring board of this example, as shown in FIG. 4, the elliptical sub slits 14 are provided at the corner portions 501 of the respective electronic component mounting boards 5. The inner wall of the sub slit 14 is curved in a convex shape with respect to the inside of the electronic component mounting substrate 5. The sub slit 14 is provided at the end of the cutting slit 2.
[0027]
The electronic component mounting board 5 is punched along the outer dimension line 500. Thereby, a part of the inner wall of the sub slit 14 becomes the corner portion 501 of the electronic component mounting substrate 5. The corner portion 501 is concavely curved with respect to the inside of the electronic component mounting substrate 5.
Others are the same as in the first embodiment.
Also in this example, the same effects as those of the first embodiment can be obtained.
[0028]
Embodiment 4
In the printed wiring board of this example, as shown in FIG. 5, bow-shaped sub-slits 15 are provided at corner portions 502 of each electronic component mounting board 5. The inner wall of the sub slit 15 is curved in a concave shape with respect to the inside of the electronic component mounting substrate 5. The sub slit 15 extends in an oblique direction of the cutting slit 2 from the side surface portion 29 of the cutting slit 2.
[0029]
When the electronic component mounting substrate 5 is punched out along the outer dimension line 500, a part of the inner wall of the sub slit 15 becomes the corner portion 502 of the electronic component mounting substrate 5. The corner portion 502 is curved in a convex shape with respect to the inside of the electronic component mounting substrate 5.
Others are the same as in the first embodiment.
Also in this example, the same effects as those of the first embodiment can be obtained.
[0030]
【The invention's effect】
According to the present invention, it is possible to provide a printed wiring board in which a large number of electronic component mounting boards are arranged, which can prevent occurrence of cracks and prevent a short circuit between an internal circuit and an external circuit.
[Brief description of the drawings]
FIG. 1 is a plan view of a printed wiring board according to Embodiment 1;
FIG. 2 is a plan view of a separated electronic component mounting board in Embodiment 1;
3 is a plan view of a printed wiring board in Embodiment 2. FIG.
4 is a plan view of a printed wiring board according to Embodiment 3. FIG.
FIG. 5 is a plan view of a printed wiring board according to Embodiment 4;
FIG. 6 is a cross-sectional view of an electronic component mounting board in a conventional example.
FIG. 7 is a plan view of a printed wiring board in a conventional example.
FIG. 8 is a plan view of a printed wiring board in which electronic components are mounted on a mounting portion in a conventional example.
FIG. 9 is a plan view of a printed wiring board in which electronic components and bonding wires are sealed with a sealing resin in a conventional example.
FIG. 10 is a plan view of an electronic component mounting board that is separated into pieces in a conventional example.
FIG. 11 is an explanatory diagram showing a problem of a conventional example.
[Explanation of symbols]
11, 12, 13, 14, 15. . . Sub slit,
2. . . Cutting slit,
31, 32. . . Insulating substrate,
5. . . Electronic component mounting board,
50, 501, 502. . . Corner,
53,590. . . External circuit,
55. . . Internal circuit,
57. . . Bridge connection,
7. . . Printed wiring board,
8). . . Electronic components,
9. . . Sealing resin,

Claims (5)

A large number of electronic component mounting substrates for mounting electronic components are arranged, and a cutting slit is provided between each electronic component mounting substrate, and along the outer dimension line away from the cutting slit. A printed wiring board in which the electronic component mounting board is punched out by a mold ,
A metal-plated mold gate provided at one corner of the electronic component mounting substrate for introducing a sealing resin into the electronic component mounting substrate;
Provided other corner portion of the electronic component mounting board, a printed wiring board, characterized in that it comprises a sub-slit extending obliquely from said cutting slit.   2. The printed wiring board according to claim 1, wherein the inner wall of the sub-slit is either linear or curved.   3. The printed wiring board according to claim 1, wherein the sub slit is any one of a rectangle, a circle, an ellipse, and a triangle.   The printed wiring board according to claim 1, further comprising a bridge-like connecting portion between the cutting slit and the sub slit.   5. The electronic component mounting substrate according to claim 1, wherein an electronic component is bonded to the electronic component mounting substrate, and a bonding pad and the electronic component in the electronic component mounting substrate are connected by a bonding wire. A printed wiring board comprising: an electronic component mounted on the electronic component mounting substrate and a bonding wire covered with a sealing resin; and the electronic component mounting substrate is punched out into individual pieces.

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