JP5404118B2 - Printed wiring board - Google Patents

Description

  The present invention relates to a printed wiring board that prevents warpage of the printed wiring board, particularly during reflow, and reduces soldering defects.

  When an electronic component is placed on a printed wiring board and soldered by reflow, the printed wiring board may be warped due to heat received during reflow. This warping contributes to the solder bridge. As a warping prevention method at the time of such reflow, there is a conventional method using a jig for preventing warping, and there are those disclosed in Patent Documents 1 and 2.

  In the invention described in Patent Document 1, warping is prevented by the weight of the jig by placing a heavy and heavy jig on the printed wiring board during reflow. A printed wiring board manufactured in such a design process will be described with reference to FIG.

  FIG. 6 is a perspective view of the printed wiring board using the jig for preventing warpage. The warp prevention jig 102 is formed of stainless steel in a square shape and is arranged on the printed wiring board 103 so as to surround the semiconductor chip 101 temporarily fixed on the printed wiring board 103 during the reflow process. By fixing the printed wiring board 103 by the weight of the warp prevention jig 102 in this way, the printed wiring board 103 is prevented from warping due to heat during the reflow process.

  In the invention described in Patent Document 2, the thickness of the discarded substrate is made thicker than the thickness of the substrate body, and the warp is prevented by the strength obtained by increasing the thickness of the discarded substrate of the printed wiring board. Such a printed wiring board will be described with reference to FIG.

  FIG. 7 is a cross-sectional view of a printed wiring board in which the thickness of the discarded board is increased. The number of discarded substrates 112 divided by the cut pattern 110 is made larger than that of the substrate body 111. The discarded substrate 112 becomes thicker than the substrate body 111, the substrate strength is improved, and warping during reflow is prevented.

JP-A-6-244242 JP 2001-7453 A

  However, in the method using the jig for preventing warpage as described in Patent Document 1, it is necessary to prepare various types of jigs having different shapes and dimensions, and use different jigs according to the type of the printed wiring board. There is. Furthermore, each time the reflow is performed, it is necessary to attach and remove the jig, which takes extra time.

  In addition, the method for increasing the thickness of the discarded substrate as described in Patent Document 2 requires additional work for adding the discarded substrate to the portion of the discarded substrate, as compared with the printed wiring substrate having a uniform thickness, and the cost is high. Become.

  Therefore, the object of the present invention is to provide a printed wiring board that suppresses the generation of warpage of the printed wiring board during reflow without using a dedicated warp prevention jig and without additional work for improving the strength. There is to do.

In order to solve the above-mentioned problems, a printed wiring board according to the present invention is divided into a plurality of board bodies and a discarded board, and a printed wiring board on which electronic components are mounted while being supported while supporting an end parallel to the traveling direction. The thrown substrate extends in a direction perpendicular to the traveling direction, straddles the edge of the plurality of substrate bodies adjacent in the direction orthogonal to the traveling direction, and the edge on the most distal side in the traveling direction, Arranged at the edge on the rearmost end side in the traveling direction and the portion between the plurality of substrate bodies adjacent in the traveling direction, the thickness of the discarded substrate and the thickness of the plurality of substrate bodies are uniform. In addition, at the edge of the plurality of substrate bodies other than the portion of the discarded substrate, a notch pattern is formed that divides the plurality of substrate bodies along the traveling direction, Along the direction of travel Wherein the UNA cut pattern is not formed.

  According to the present invention, the discarded substrate is disposed across the edge of the substrate body adjacent in the direction orthogonal to the traveling direction. Therefore, the strength of the entire printed wiring board is improved in the direction orthogonal to the traveling direction. As a result, it is possible to suppress warping of the printed circuit board during reflow without using a dedicated warp prevention jig and without additional processing for improving the strength.

It is a top view which shows the structure of the printed wiring board in one Embodiment of this invention. It is a perspective view which shows the structure of the conventional printed wiring board. It is a perspective view which shows the thickness of a printed wiring board. It is a top view of a printed wiring board in case the notch pattern for board | substrate division | segmentation is formed by V cut. It is a top view which shows the structure of the printed wiring board in the modification of this invention. It is a perspective view of the conventional printed wiring board by which an electronic component is mounted using the jig | tool for prevention of warpage. It is a perspective view of the conventional printed wiring board which increased the thickness of the discard board | substrate.

  Hereinafter, a printed wiring board 3 according to an embodiment of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative positions, etc. of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified.

  FIG. 1 is a plan view showing a configuration of a printed wiring board 3 according to an embodiment of the present invention. As shown in FIG. 1, the printed wiring board 3 is divided into “plurality”, for example, four substrate bodies 1 and “plurality”, for example, three discarded substrates 2, and is impositioned. In the mounting process, the printed wiring board 3 is mounted with an electronic component (not shown) while being supported while its end parallel to the traveling direction A is supported. The advancing direction A here refers to a direction in which the printed wiring board 3 is supported by a mounting rail, for example, in the process of mounting electronic components. In addition, although the shape of each board | substrate body 1 is formed so that it may become a rectangle by planar view, it is not necessarily limited to this. The corners of the substrate body 1 may be slightly rounded, and other shapes are also included.

  The discarded substrate 2 extends in a direction orthogonal to the traveling direction A (orthogonal direction B), and is disposed across the edge of the substrate body 1 adjacent in the direction orthogonal to the traveling direction A. That is, the discarded board 2 is disposed at the edge on the most distal side in the traveling direction A of the printed wiring board 3 and the edge on the rearmost side in the traveling direction A of the printed wiring board 3. Further, the discarded substrate 2 is disposed at a portion between the substrate bodies 1 adjacent to each other in the traveling direction A of the printed wiring board 3. Such a discarded substrate 2 improves the strength of the printed wiring board 3 in the direction orthogonal to the traveling direction A, and prevents the printed wiring board 3 from warping in a V shape when viewed from the traveling direction A. The “edge” described above corresponds to, for example, a side if it is a quadrangle, and an end, that is, one point if it is a circle.

  By disposing the discarded substrate 2 and imposing it on the printed wiring board 3, the occurrence of unevenness with respect to the warp of the printed wiring board 3 is suppressed. Even when the imposition of the substrate body 1 is increased, the same effect can be obtained by disposing the discarded substrates 2 at a plurality of positions between the substrate bodies 1.

  Furthermore, when a copper foil pattern is formed on the entire surface of the discard substrate 2 and the back surface, the strength of the discard substrate 2 is further improved.

  The discarded substrate 2 is at least one of an edge portion on the most distal side in the traveling direction A, an edge portion on the rearmost end side in the traveling direction A, and a portion between the substrate bodies 1 adjacent in the traveling direction A. In some cases, it may be arranged. When the strength of the printed wiring board 3 can be secured to such an extent that it does not warp in a V shape, the number of discarded boards 2 may be appropriately reduced. Alternatively, the discarded substrate 2 may be disposed so as to extend in a direction orthogonal to the traveling direction A in all the portions between the substrate bodies 1 adjacent in the traveling direction A.

  FIG. 2 is a perspective view showing a configuration of a conventional printed wiring board 30. As shown in FIG. 2, the discarded substrate 2 is not disposed on the printed wiring board 30 in the direction orthogonal to the traveling direction A. Since the discarded substrate 2 is not disposed, the printed wiring board 30 is easily warped in a V shape. As shown in FIG. 2, the printed wiring board 30 is supported in a state in which the left and right sides are sandwiched between two mounting rails 5 in the traveling direction A. Therefore, the printed wiring board 30 does not warp in the traveling direction A. However, the printed wiring board 30 may be warped in a V shape in the direction orthogonal to the traveling direction A because the strength is reduced by the cut pattern 4 for dividing the board extending in the traveling direction A. . Such a fear is eliminated by the presence of the discarded substrate 2 shown in FIG.

  FIG. 3 is a perspective view showing the thickness of the printed wiring board 3. As shown in FIG. 3, the printed wiring board 3 is configured such that the thickness H2 of the discarded board and the thickness H1 of the board body are uniform (same). And between the board | substrate bodies 1 which adjoin each other, or between the board | substrate body 1 and the discard board | substrate 2, there exists a location where the notch pattern 4 is formed in perforated form. As described above, since the plurality of discarded substrates 2 are arranged apart from each other in the direction orthogonal to the traveling direction A on the printed wiring board 3, the strength of the printed wiring board 3 against warping is improved. Therefore, unlike the prior art, it is not necessary to increase the strength of the discarded substrate 2 by increasing the thickness of the discarded substrate 2 by additional processing.

  The cut pattern 4 is formed at the edge of the substrate body 1 in order to divide the substrate body 1. The cut pattern 4 is formed along the discarded substrate 2 between the substrate bodies 1 adjacent in the traveling direction A. Further, the cut pattern 4 is formed between the substrate bodies 1 adjacent to each other in the width direction orthogonal to the traveling direction A. As described above, the cut pattern 4 is formed at the edge of the substrate body 1 other than the portion of the discarded substrate 2. That is, the notch pattern 4 for dividing the substrate is not disposed on the discarded substrate 2. The cut pattern 4 is disposed avoiding the discarded substrate 2. In the printed wiring board 3 described above, the cut pattern 4 along the discarded board 2 between the board bodies 1 adjacent in the traveling direction A is separated by the discarded board 2 so as not to straddle the discarded board 2. Thereby, the strength of the printed wiring board 3 is improved.

  The cut pattern 4 is formed in a perforated shape. This is because the perforated shape of the printed wiring board 3 as a whole can have a stronger strength against warpage than in the case of the V-cut.

  FIG. 4 is a plan view of the printed wiring board 40 when the cut pattern for dividing the board is formed by V-cut. For example, when four substrate bodies 1 are partitioned on the printed wiring board 40, the perforation pattern 6 for dividing the substrate body 1 is usually a perforation or a V cut.

  However, when the cut pattern 6 for dividing the substrate is used in a V-cut, the cut pattern 6 is disposed up to the discarded substrate 2 as shown in FIG. It will decline. Therefore, the cut pattern 6 for dividing the substrate needs to be a perforation that can be arranged only at a place where the substrate body 1 is divided (see FIG. 3).

  According to the printed wiring board 3 of this embodiment described above, the discarded board 2 is disposed across the edge of the board body 1 adjacent in the direction orthogonal to the traveling direction A. Therefore, the strength of the entire printed wiring board 3 is improved in the direction orthogonal to the traveling direction A. As a result, it is possible to suppress the warpage of the printed wiring board 3 during reflow without using a dedicated warp prevention jig and without additional processing for improving the strength.

  In addition, unlike the prior art, there is no need to use a warp preventing jig, and the cost increase for the additional work of the printed wiring board as in the conventional example is suppressed.

  FIG. 5 is a plan view showing the configuration of the printed wiring board 31 according to a modification of the present invention. As shown in FIG. 5, the discarded substrate 2 does not necessarily have to be disposed along the entire edge of the substrate body 1 in the width direction orthogonal to the traveling direction A. The discarded substrate 2 may be disposed only at a part of the edge of the substrate body 1 as long as it can be disposed across the adjacent substrate bodies 1 in the width direction orthogonal to the traveling direction A.

DESCRIPTION OF SYMBOLS 1 Board body 2 Discarded board 3, 31 ... Printed wiring board 4 Notch pattern 5 Mounting rail A Traveling direction

Claims (5)

In a printed circuit board on which electronic components are mounted while being divided into a plurality of substrate bodies and discarded substrates and supported while being supported at an end parallel to the traveling direction,
The discarded substrate extends in a direction orthogonal to the traveling direction, straddles the edge of the plurality of substrate bodies adjacent in the direction orthogonal to the traveling direction, the edge on the most distal side in the traveling direction, and the traveling Arranged at a portion between the plurality of substrate bodies adjacent to each other in the advancing direction, and an edge portion on the rearmost side in the direction,
The thickness of the discarded substrate and the thickness of the plurality of substrate bodies are uniform,
At the edge of the plurality of substrate bodies other than the portion of the discarded substrate, a notch pattern is formed that divides the plurality of substrate bodies along the traveling direction,
The printed circuit board is characterized in that a cut pattern is not formed on the discarded substrate along the traveling direction . In a direction orthogonal to the traveling direction, the length of the discarded substrate at the edge on the most distal side in the traveling direction and the edge on the rearmost end side in the traveling direction is set to be equal to or less than the length of the plurality of substrate bodies. The printed wiring board according to claim 1, wherein the printed wiring board is a printed wiring board. In the direction orthogonal to the traveling direction, the length of the discarded substrate at the edge on the most distal side in the traveling direction and the edge on the rearmost side in the traveling direction is set shorter than the length of the plurality of substrate bodies. The printed wiring board according to claim 2, wherein the printed wiring board is a printed wiring board.   The printed wiring board according to any one of claims 1 to 3, wherein a copper foil pattern is formed on the entire surface of the front and back surfaces of the discarded substrate. Printed circuit board according to any one of claims 1 to 4 wherein the cut pattern is being formed in the perforated line.